ADVS 5630 Final Exam- Comprehensive (Exams 1-4)
Nitric Oxide (NO) bioregulator
"Endothelium-derived relaxing factor"
Type 2 Endocrine System
"Free-standing" endocrine glands (Ex. parathyroid, islet cells)
Indoleamine: Serotonin
"Happiness hormone;" Precursor to Melatonin
What is an example of a typical bioassay experiment?
"Inject 'em and inspect 'em;" Ex. Induce ovulation by injection of Luteinizing Hormone
Cells responsible for secreting tropic hormones are designated with the suffix "-______."
"Trope"
What is typically used to designate Steroid membrane receptors? (ER, AR)
"m"; Ex. mER, mAR
What are the 4 endocrine tissues of the adrenal gland from most exterior to most interior?
(Capsule) 1) Zona glomerulosa 2) Zona fasciculata 3) Zona reticularis 4) Adrenal Medulla
Prostaglandin (Structure)
(PGE1)
What are the symptoms of Addison's Disease?
(similar to many other conditions) 1) Anorexia 2) Arrhythmias 3) Dehydration 4) Depression 5) Gastrointestinal disturbances (vomiting & diarrhea) 6) Hypoglycemia 7) Lethargy 8) Shaking/listlessness 9) Weakness 10) Weight loss
What is the percentage of T3 in blood? T4?
0.03%; 0.3%
In an estrous cycle, ___ follicle(s) is recruited for rapid development to become a mature (Graafian) follicle.
1
How many corpus luteum form for every ovulated follicle?
1 Corpus luteum per ovulated follicle
How many cell types are responsible for the synthesis and release of each tropic hormone?
1 cell type
What are the Type 1 hormones TSH and LH's half-life?
1 hour or less
How many functional gametes are produced by Oogenesis of one oogonium?
1 mature gamete, the ovum
In humans, complete development from a primordial follicle to an ovulated follicle takes nearly ______.
1 year
What are the 2 ways that T4 is metabolized?
1) 33 to 40% is deiodinated in liver to form T3 2) 15 to 20% is deaminated and decarboxylated in liver yielding TETRAC
What are the 2 genetic defects and steroidogenic enzymes that lead to Congenital Adrenal Hyperplasia (CAH)?
1) Absence of 21α-hydroxylase (90%) 2) Mutation in 11β-hydroxylase
What are 2 causes of Acromegaly, a dysregulation in GH release?
1) Absence of sufficient SST to suppress GH 2) Absence of negative feedback (IGF-I issues)
What are 4 defining characteristics of Steroid-secreting Cells?
1) Abundance of SER 2) Mitochondria have tubular cristae 3) Steroids not stored in cell 4) Cholesterol-containing lipid droplets common
What are 5 triggers for release of the catecholamines Epinephrine and Norepinephrine from the Adrenal Medulla?
1) Accelerated heart rate 2) Hydrolysis of glycogen to glucose in liver (E, NE) and muscle (E only) 3) Fear triggers release of E; positive anticipation NE 4) Exercise increases NE, but only intense exercise triggers E release 5) Hypoxia and asphyxia triggers E
What are 3 examples of Neurotransmitters?
1) Acetylcholine 2) Dopamine 3) GABA
What are the 4 other miscellaneous bioregulator mentioned?
1) Acetylcholine 2) GABA (Gamma-AminoButryic Acid) 3) Interleukins 4) Gaseous regulators (Nitric oxide (NO), Carbon monoxide (CO))
What are 3 examples of amino acid, peptide, and protein hormones that use G Protein-Coupled Receptors (GPCR)?
1) Acetylcholine 2) Vasopressin 3) Catecholamines: Dopamine, norepinephrine, epinephrine
What are 2 disorders of the Pituitary mentioned?
1) Acromegaly 2) Dwarfism
What is the process of Catecholamine release?
1) Action potential triggers Ca²⁺ channels, increases intracellular Ca²⁺, triggers release of neurotransmitter from storage vesicle 2) After release, NE diffuses out of vesicle and is either taken up into emitting cell or postsynaptic cell
What are 2 functions of Carbon Monoxide (CO) bioregulator?
1) Acts as trigger for 2nd messenger pathways 2) Promotes dilation of blood vessels
What are some common endocrine disorders/diseases? (8)
1) Addison's 2) Diabetes insipidus 3) Diabetes mellitus 4) Gigantism 5) Goiter 6) Grave's disease 7) Hyperaldosteronism 8) Polycycstic ovarian disease
What are 2 diseases of glucocorticoid hyposecretion?
1) Addison's Disease 2) Congenital Adrenal Hyperplasia (CAH)
What are the 2 lobes of the Pituitary Gland or Hypophysis called?
1) Adenohypophysis: Anterior lobe 2) Neurohypophysis: Posterior lobe
What are the 2 distinct regions with differing functions of the adrenal gland?
1) Adrenal cortex (outer) 2) Adrenal medulla (inner)
What are the 4 causes of Hypoaldosteronism?
1) Adrenalectomy or Addison's disease 2) Congenital (CAH) 3) Drug-induced depression 4) Defects in renin-angiotensin system
What are the 2 Type 3: Smaller peptide hormones?
1) Adrenocorticotropic hormone (ACTH) 2) Melanotropin (α-MSH)
What are the 6 tropic hormones produced by 5 cell types secreted by the Pars distalis of the Adenohypophysis?
1) Adrenocorticotropin 2) Thyrotropin 3) Growth hormone 4) Prolactin 5) Gonadotropin: Follicle-stimulating hormone 6) Gonadotropin: Luteinizing hormone
The Pars intermedia is present in most animals, but some animals do lack a Pars intermedia. What are 5 examples of animals that lack a Pars intermedia?
1) Adult humans 2) Whales 3) Manatees 4) Elephants 5) Beaver (most lack hair)
What are the 3 phases of Selye's General Adaptation Syndrome? (Stress Model)
1) Alarm ("Fight or Flight") 2) Resistance 3) Exhaustion or Recovery (Stressor is removed or adaptation)
What are the 2 major components to the basic structure of mammary glands?
1) Alveoli 2) Myoepithelial cells 3) Ducts
What are the 4 main categories of bioregulators?
1) Amino acids, amines, peptides, proteins 2) Steroids 3) Thyroid hormones 4) Eicosanoids
What are the 2 nonapeptides present in the Pars nervosa of most adult mammals?
1) Arginine vasopressin (AVP) 2) Oxytocin (OXY)
What are 2 other factors that control the release of Aldosterone, besides the Renin-Angiotensin System?
1) Atrial Natriuretic Peptide (ANP) 2) Brain Natriuretic Peptide (BNP)
What are the 3 typical causes of Addison's Disease?
1) Atrophy from autoimmune attack 2) Drug-induced or congenital dysfunction of steroidogenic enzymes 3) Complication of AIDS
What are estrogens 3 key physiological roles in males?
1) Block androgen synthesis by Leydig cells 2) Influence responsiveness of Leydig cells to gonadotropins 3) Regulate resorption of fluid in epididymis
What are the 2 general functions of Thromboxanes? (Eicosanoid)
1) Blood clot formation 2) Alter platelet structure
What are 2 examples of Homeostasis?
1) Blood osmotic pressure 2) Concentration of calcium, sodium, glucose in blood
What is the "Life History" of a Hormone?
1) Born in endocrine cell 2) Spends short life free in the blood or bound to binding proteins 3) Metabolized and/or excreted ("die") before or after it binds to a target cell where it causes changes that result in its characteristic effect 4) In some cases, hormone is secreted in inactive form and must be metabolized to active form before it can bind to receptor and produce an effect
What is the complicated lifecycle of salmonid species?
1) Born in freshwater 2) Migrate to ocean 3) Return to freshwater for breeding
The source of Relaxin differs depending on species. What are the 3 sources mentioned?
1) CL: In animals that retain CL throughout pregnancy 2) Interstitial cells after CL regresses 3) Placenta: Major source in horses
What is the process of the Type 1 Endocrine System (Hypothalamic-pituitary-target gland)?
1) CNS regulates secretion of releasing hormones from brain (Hypothalamus) 2) Pituitary stimulated to produce tropic hormones 3) Tropic hormones act on peripheral endocrine glands 4) Endocrine glands release hormones to target organs and provide feedback to brain (hypothalamus)
Hormonal control of parturition in Humans
1) CRH from placenta initiates birth by stimulating production of prostaglandins in uterine myometrium 2) Prostaglandins induce myometrial contractions
Both regions of the Neurohypophysis, the Median eminence and Pars nervosa, are composed of what 2 components?
1) Capillaries 2) Axonal extensions of neurosecretory cells originating in hypothalamus
Thyroid glands have innervation at what 2 locations?
1) Capillaries: Cholinergic 2) Follicle cells: Adrenergic, Peptidergic, Neuropeptide Y
What are 2 categories of amino acid, peptide and protein bioregulators made up of a single amino acid?
1) Catecholamines 2) Indoleamines
What are the 3 major categories of amino acid, peptide and protein bioregulators?
1) Catecholamines 2) Indoleamines 3) Peptides
What is the synthesis process of Vitamin D and 1,25-DHC?
1) Cholesterol converted by UV light in skin to Vitamin D3 (Cholecalciferol) 2) Liver converts to 25-HC 3) Kidney converts to 1,25-DHC (Active form)
What are the 2 Type 1: Glycoprotein Placental (chorionic) tropic hormones?
1) Chorionic gonadotropin (CG) 2) Chorionic thyrotropin (CT)
What are some examples of the combined Estrogen + Progestin method of female hormonal contraception?
1) Combined oral contraceptive pills 2) NuvaRing
What are the 3 key points of the Exhaustion Phase of Selye's General Adaptation Syndrome?
1) Continued stressful stimuli ultimately leads to death (if no adaptation) 2) General debilitation of body 3) Prolonged hyperglycemia, increased neurodegeneration, immune suppression
What are 3 examples of Oxytocin's (OXY) function in stimulating smooth muscle contraction?
1) Contraction of myoepithelial cells causing milk ejection 2) Uterus, involved in induction of labor 3) Oviducts and sperm ducts
What are the primary steroids made by the Zona fasciculata?
1) Corticosterone 2) Cortisol
What are the 2 stimulatory hormones involved in the regulation of Adrenocorticotropin (ACTH) or Corticotropin?
1) Corticotropin-Releasing Hormone (CRH) 2) Arginine Vasopressin (AVP)
How is Addison's Disease detected?
1) Cortisol test 2) Blood chemistry profile
What are the 4 feedback loops present in the normal HPA Axis?
1) Cortisol: Negative feedback on both hypothalamus and pituitary 2) CRH: Positive feedback on pituitary 3) ACTH: Positive feedback on adrenal gland 4) Stress: Positive feedback on hypothalamus
What are the clinical signs of a Progesterone-secreting or luteinized cyst in Cystic Ovarian Disease (COD) in cattle?
1) Cow is not observed in heat 2) Prolonged inter-estrus interval 3) Anestrous
What are the 2 routes of neurohormones in Hypothalamus-pituitary communication?
1) DIRECT release to circulation of neurohormones to capillary system of Pars nervosa (bypass Median eminence) 2) INDIRECT: Release of neurohormones into Median eminence capillary system, which travel to anterior pituitary through capillaries and reach target cells, the "tropes"
The Indoleamine Melatonin is increased in response to what 2 factors?
1) Darkness 2) Hypoglycemia
What are the 4 steps in the Homeostatic Model?
1) Detection of information by receptor that converts it into biological cues or input and transmits to controller 2) Controller compares input to set point and makes physiological adjustments by producing output 3) Output travels by specific pathway to effectors 4) Effectors cause change in system that feeds back via same or different receptors to alert controller change has occurred
In mammary glands and lactation, what 3 functions do hormones control?
1) Development of mammary glands 2) Synthesis of milk 3) Ejection of milk to suckling offspring
What are the 3 actions of androgens in circulation?
1) Development/maintenance of glands/accessory structures 2) Development of secondary sexual characteristics (i.e. beard development, skeletal muscles) 3) Negative feedback at hypothalamus
What are the treatments for Polycystic Ovarian Syndrome (PCOS/POD)?
1) Diet modification to reduce weight 2) Medications to treat insulin resistance 3) Infertility treatments 4) Drug treatment to alleviate androgenic symptoms
What are 2 examples of sexual dimorphism in the brain?
1) Difference in density of neurons and size of medial preoptic area 2) Vomeronasal organ (auxiliary olfactory sense organ)
What are some common endocrine disrupting compounds? (8)
1) Dioxins 2) Heavy metals 3) Phthalates 4) Exogenous steroids 5) Pesticides 6) PCB's 7) PFAA's 8) Alkylphenols
What are 3 important Catecholamines?
1) Dopamine 2) Norepinephrine 3) Epinephrine (Adrenaline)
What are the 2 hormones involved in PRL regulation?
1) Dopamine (DA), also called Prolactin-Release Inhibiting Hormone (PRIH) 2) Prolactin-releasing hormone (PRH) or VIP
What are 2 examples of Allelomones?
1) E2-butenyl 2) Methyldisulfide
What are the 3 effects of adrenal catecholamines Epinephrine and Norepinephrine on metabolism in response to stress?
1) Emotional (anxiety, apprehension) 2) Physical (injury, exercise) 3) Physiological (temperature, pH, oxygen availability, hypotension, hypoglycemia)
What are the possible causes of Primary Amenorrhea?
1) Endocrine causes related to disorders of HPG axis 2) Poor nutrition, stress, rigorous athletic training
What is the process of the Type 2 Endocrine System ("Free-standing" endocrine glands)?
1) Endocrine glands release hormones that stimulate a target tissue to produce an effect (Ex. rise in serum calcium or fall in blood sugar) 2) This effect may in turn modify the function of the gland
What are 4 examples of a Type 2 Endocrine System ("Free-standing" endocrine glands)?
1) Endocrine pancreas (insulin) 2) Adipose tissue 3) Thymus 4) Parathyroid
What are the 5 functions of Activin?
1) Enhances FSH synthesis/secretion 2) Enhances FSH binding and FSH-induced aromatization of T to E2 3) Enhances spermatogenesis in males 4) Participates in regulation of menstrual cycle 5) Important during morphogenesis, development of branching organs (kidney, prostate, lung)
What are 3 reasons why pulsatile secretion of GnRH is important?
1) Ensure that Leydig cells do not become insensitive to stimulation by LH 2) Prevent breakdown in metabolic pathway for clearance of testosterone 3) Maintain proper neuroendocrine negative feedback
What is the pathway for cyclic AMP as a critical 2nd messenger?
1) Epinephrine (hormone) binds to GPCR receptor, which has stimulatory Gs subunit 2) Gs activates adenylyl cyclase producing cAMP from ATP 3) cAMP activates kinases, which phosphorylate other target proteins (In this example, the ultimate result of epinephrine activation of its GPCR is release of glucose)
Uterine cycle: Secretory phase
1) Estradiol maintains proliferation of endometrium 2) Progesterone stimulates production of embryotroph, source of nourishment for unimplanted embryo 3) E2 and P4 maintain vascularized state of endometrium
Uterine cycle: Proliferative phase
1) Estradiol produced during follicular phase stimulates proliferation of the endometrium to prepare for implantation of embryo 2) Estradiol also increases vasculature of the endometrial Functional layer
What is the process of Vitellogenesis?
1) Estradiol, produced by follicle, travels to liver 2) Estradiol stimulates production of Vitellogenin (Vtg) 3) Vtg is transported via blood back to ovary and is incorporated into developing oocytes 4) Vtg is converted to yolk proteins
What hormones play a role in birth? (6)
1) Estrogen 2) Progesterone 3) Oxytocin 4) Prostaglandins (PGF2α) 5) Relaxin 6) CRH, Corticosteroids
What are the 2 hormone mixtures utilized in female hormonal contraception?
1) Estrogen + Progestin 2) Progestin
What are the 2 types of cysts possible in Cystic Ovarian Disease (COD) in cattle?
1) Estrogen-secreting or Follicular cyst 2) Progesterone-secreting or luteinized cyst
What hormones are involved in the expansion of Alveoli, aka lobuloalveolar growth? How are these hormones significant?
1) Estrogens 2) Progesterone 3) PRL 4) GH 5) Relaxin 6) Corticosteroids Same hormones needed for parturition
Some actions of PRL requires interaction with other hormones. What are 3 of these interactions?
1) Estrogens: Make mammary gland tissues more responsive to PRL 2) Glucocorticoids: Increase action strength of PRL 3) Progesterones: Inhibit PRL actions at mammary gland, blocking lactogenesis
What are the 8 symptoms of Cushing's Disease in horses?
1) Excessive drinking/urination 2) Increased appetite 3) Abnormal hair growth/shedding (heavy, course, curly hair coat; Does not shed in summer) 4) Drab coat 5) Swayback stance and potbelly 6) Fat accumulation above eyes 7) Chronic laminitis 8) Compromised immune system
What are the effects of testosterone's conversion to Dihydrotestosterone (DHT) in men?
1) Facial/body hair 2) Acne 3) Hair loss 4) Prostate growth
What are the 4 steps to glomerular filtration in the kidney?
1) Filtration 2) Reabsorption 3) Secretion 4) Excretion
Gonadotrope: Hormones secreted (2)
1) Follicle-stimulating hormone (FSH) 2) Luteinizing hormone (LH)
What are the 2 phases of the Estrous cycle, named for the dominant ovarian structure present in the ovary at the time?
1) Follicular phase 2) Luteal phase
What are 3 examples of Hormones?
1) GH 2) Insulin 3) Estradiol
What are the 2 types of Cell-surface receptors used by amino acid, peptide, and protein hormones?
1) GPCRs 2) Receptor Tyrosine Kinases (RTKs)
What are 3 genetic and genomic approaches used with hormones?
1) Gene expression 2) Molecule interactions 3) Gene reporter assays
What are the consequences of Hypothyroidism in adults?
1) Generalized decrease in metabolism 2) Slower heart rate 3) Lower oxygen consumption
What are the 2 key points of the Alarm Phase of Selye's General Adaptation Syndrome?
1) Generalized increase in sympathetic nervous system (regulates body's response to stress- fight or flight) 2) Stress triggers release of glucocorticoids
In aquaculture, application of hormones can be employed to produce stock of all one sex. How is this accomplished?
1) Genetic females are treated with an androgen (methyltestosterone) 2) Androgen blocks ovarian development, producing phenotypic males 3) When bred to genetic females, yields all females
What are the causes of Cystic Ovarian Disease (COD) in cattle?
1) Genetic predisposition 2) Negative energy balance brought on by milk over-production 3) Stress, disease
What are the 3 strategies of sex determination in vertebrates?
1) Genetic sex determination (XX/XY, ZZ/ZW) 2) Temperature-dependent sex determination 3) Behavioral sex determination
What are 2 types of corticosteroid nuclear receptors found in the cytoplasm and nucleus?
1) Glucocorticoid receptors (GR) 2) Mineralcorticoid receptors (MR)
What are 4 causes of Cushing's Syndrome?
1) Glucocorticoid therapy (most common) 2) Excess secretion of ACTH by pituitary 3) Elevated cortisol production by adrenal adenoma or carcinoma 4) Hormone-producing cancers (Bronchial carcinoid tumor, pancreatic carcinoid tumor, medullary thyroid carcinoma)
What are the 3 hormones produced in the Resistance Phase of Selye's General Adaptation Syndrome?
1) Glucocorticoids 2) Aldosterone from Renin-Angiotensin System 3) GH
What are 2 examples of granulated tropic cells?
1) Gonadotrope 2) Corticotrope
Upon differentiation, Primary follicles develop 2 cell layers. What are these 2 cell layers and what do they differentiate from?
1) Granulosa cells; Differentiate from the follicle cells 2) Theca cells; Differentiate from stromal cells
What are the 2 Type 2: Long peptide chain hormones?
1) Growth hormone (GH) 2) Prolactin (PRL)
What are 2 types of Thyroiditis mentioned?
1) Hashimoto's Thyroiditis (most common) 2) Riedel's Thyroiditis
What are 5 organs that contain hormone-secreting tissues?
1) Heart 2) Thymus 3) Digestive Tract 4) Kidneys 5) Gonads
What are 2 chemical separation methods used with hormones? (often used in tandem)
1) High Performance Liquid Chromatography (HPLC) 2) Mass spectrometry (MS)
To function properly, what 4 characteristics must receptors have?
1) High affinity for hormone (strong tendency to bind) 2) High specificity (will not easily bind other hormones) 3) Low capacity (few enough receptors so that low amounts of hormone will occupy all of the binding sites) 4) Receptors must be present in target tissues
What are the 3 steps to the Kinase Cascade Hypothesis?
1) Hormone binding triggers activation of signal transduction complex 2) Leads to activation of MAPK or Mitogen-Activated Protein Kinase cascade 3) Final target of cascade is transcription factor activating gene transcription
What is the mechanism of action of Thyroid hormones?
1) Hormone binds nuclear receptors 2) Receptors form Heterodimers 3) Receptors bind to Thyroid Hormone Response Elements (TREs) in DNA 4) Transcription occurs
What is the mechanism of action of Thyroid hormones?
1) Hormone binds nuclear receptors and reveals "zinc-fingers" 2) Receptors form Heterodimers 3) Receptors bind to Thyroid Hormone Response Elements (TREs) in DNA 4) Transcription occurs
What is the pathway for Ca²⁺ as a 2nd messenger? (Similar to cAMP pathway)
1) Hormone binds receptor, triggering activation of Gq subunit 2) Gq activates phospholipase C (PLC), which converts PIP2 to IP3 and DAG 3) IP3 releases stored intracellular Ca²⁺ from ER
What do the side-effects of Menopause include?
1) Hot flashes 2) Reduced libido 3) Accelerated bone resorption 4) Calcium deficiency
What are the 2 major disorders of Aldosterone secretion?
1) Hyperaldosteronism 2) Hypoaldosteronism
What are the clinical signs of an Estrogen-secreting or Follicular cyst in Cystic Ovarian Disease (COD) in cattle?
1) Hyperestrogenization 2) Nymphomania: Permanent estrus behavior 3) Decreased milk production
What are 3 examples of a Type 1 Endocrine System (Hypothalamic-pituitary-target gland)?
1) Hypothalamic-pituitary-gonadal axis 2) Hypothalamic-pituitary-adrenal axis 3) Hypothalamic-pituitary-thyroid axis
What are the 7 organs of the Endocrine System?
1) Hypothalamus 2) Pituitary Gland 3) Thyroid Gland 4) Adrenal Glands 5) Pancreas (Pancreatic Islets) 6) Pineal Gland 7) Parathyroid Glands
What is the cycle of thyroid hormone homeostasis, beginning with a disturbance in homeostasis resulting in decreased T4, T3 concentrations in blood or low body temperature?
1) Hypothalamus releases TRH 2) Pituitary releases TSH 3) Thyroid gland follicles release T4, T3 4) Homeostasis restored by an increase in T4,T3 concentrations in blood; Increase in body temperature
What is the Adrenocorticotropin (ACTH) pathway?
1) Hypothalamus secretes CRH, and AVP in times of stress 2) Pituitary corticotropes secrete ACTH 3) Adrenal cortex secretes corticosteroids to target organs to take intracrine effect
What is the pathway of the Hypothalamus-Pituitary-Adrenal (HPA) Axis?
1) Hypothalamus secretes Corticotropin Releasing Hormone (CRH), and AVP in times of stress 2) Pituitary corticotropes secrete Adrenocorticotropin (ACTH) 3) Adrenal Cortex (Adrenal gland) secretes corticosteroids to target organs to take intracrine effect
What is the Growth Hormone (GH) pathway?
1) Hypothalamus secretes GHRH (stimulatory) 2) Pituitary somatotropes secrete GH only if SST (inhibitory) is low 3) GH induces expression of IGF-I in liver to take intracrine effect
What is the pathway of the Hypothalamic-pituitary-gonadal axis (HPG) in males?
1) Hypothalamus secretes GnRH 2) Pituitary secretes gonadotropins FSH and LH 3) FSH acts on Sertoli cells; LH acts on Leydig cells 4) Sertoli cells release Inhibin in negative feedback to pituitary 5) Leydig cells produce testosterone with negative feedback to hypothalamus and positive feedback to sertoli cells to increase Inhibin
What is the Gonadotropin (GTH) pathway?
1) Hypothalamus secretes GnRH (stimulatory) 2) Pituitary gonadotropes secrete FSH and LH 3) Gonads release sex steroids to target organs to take intracrine effect
What is the pathway of the Hypothalamic-pituitary-gonadal axis (HPG)?
1) Hypothalamus secretes GnRH due to CNS input 2) Pituitary gonadotropes secrete FSH and LH 3) Gonads release estrogens, androgens, and progestogens to target organs to take intracrine effect
What is the Prolactin (PRL) pathway?
1) Hypothalamus secretes PRH (VIP) 2) Dopamine or PRIH (inhibitory) brake is overcome and Pituitary lactotropes secrete PRL to mammary glands
What is the Thyroid-Stimulating Hormone (TSH) pathway?
1) Hypothalamus secretes Thyrotropin-Releasing Hormone (TRH) due to CNS input 2) Pituitary thyrotropes secrete Thyroid-stimulating hormone (TSH), upon activation by VIP 3) Thyroid releases T3 and T4 to target organs to take intracrine effect
What is the Thyroid-Stimulating Hormone (TSH) pathway?
1) Hypothalamus secretes Thyrotropin-Releasing Hormone TRH (stimulatory) 2) Pituitary thyrotropes secrete Thyroid-stimulating hormone (TSH), upon activation by VIP 3) Thyroid releases T3 and T4 to target organs to take intracrine effect
What are 4 examples of a Type 2 Endocrine System? (w/abbreviation)
1) Hypothalamus-pituitary-thyroid (HPT) 2) Hypothalamus-pituitary-hepatic (HPH) 3) Hypothalamus-pituitary-adrenal (HPA) 4) Hypothalamus-pituitary-gonad (HPG)
What are the 4 causes of Precocious Puberty?
1) Idiopathic 2) Pineal tumor 3) Ectopic gonadotropin or gonadal steroids 4) Exposure to endocrine disrupting chemicals
What are 2 Immunoassays used with hormones?
1) Immunohistochemistry (IHC) 2) Enzyme-Linked Immunoabsorbant Assay (ELISA)
What are the 5 major symptoms of Canine Cushing's Disease?
1) Increased drinking/urination 2) Increased appetite/weight gain 3) Hair loss 4) Hyperpigmentation 5) Pendulous abdomen
What are thyroid hormones' 6 effects on peripheral tissues?
1) Increases oxygen and energy consumption 2) Increases heart rate (blood pressure) 3) Increases sensitivity to sympathetic stimulation 4) Maintains normal sensitivity of respiratory centers to changes in O2 and CO2 concentrations 5) Stimulates RBC formation, enhances O2 delivery 6) Stimulates activity in other endocrine tissues
What are 2 functions of the Type 1 Thyroid-Stimulating Hormone (TSH)?
1) Increases synthesis and release of stored thyroid hormones 2) Increases iodide uptake by thyroid follicle cells
What are 4 actions of FSH in males?
1) Indirectly initiates spermatogenesis 2) Increases expression of aromatase in Sertoli cells 3) Increases expression of androgen-binding protein (ABP) 4) Increases Inhibin expression
What are Glucocorticoids' (Cortisol) 4 effects on energy metabolism?
1) Inhibit glucose utilization by peripheral tissues 2) Stimulate AA transport to liver 3) Stimulate conversion of AA into glucose and glycogen by liver cells: Gluconeogenesis 4) Increase mobilization of fat stores in non-neural tissues
What does the combined Estrogen + Progestin method of female hormonal contraception cause?
1) Inhibits follicle development 2) Prevents ovulation
What are 2 examples of amino acid, peptide, and protein hormones that use Receptor Tyrosine Kinases (RTKs)?
1) Insulin 2) Growth hormone
What is the mechanism of Prednisone (glucocorticoid) action?
1) Interferes with release of histamines 2) Reduces inflammatory reaction 3) Decreased production of prostaglandins (leukotrienes)
What are the 4 key steps of thyroid hormone synthesis?
1) Iodide transport by the NIS 2) Active thyroid peroxidase (TPO) 3) Active thyroglobulin (Tg) 4) Release of thyroid hormone
What is the treatment for Goiters?
1) Iodine supplementation 2) Treatment of underlying condition (i.e. hormone replacement such as levothyroxine)
What are the 4 critical aspects of thyroid hormone synthesis that are regulated by TSH?
1) Iodine transport by the NIS 2) Expression of Tg gene 3) Expression of TPO 4) Release of thyroid hormone
What are 2 forms of Precocious Puberty?
1) Isosexual precocity 2) Heterosexual precocity
What is the primary pathway for steroid production in the testis (2-cell pathway)?
1) LH acts on Leydig cells to produce androgens 2) Androgens (lipophilic) passively diffuse through basal lamina to Sertoli cells 3) FSH increases aromatase activity in Sertoli cells 4) Testosterone is converted to estrogen by aromatase
What is the 2-cell model of steroidogenesis in the ovaries?
1) LH causes Thecal cells to produce androgens 2) Androgens cross basal lamina to Granulosa cells 3) FSH increases aromatase conversion of androgens to estrogen in Granulosa cells
What are the 2 phases of lactation?
1) Lactogenesis: Milk secretion 2) Milk ejection
What are the 3 structural parts of Nuclear Receptors?
1) Ligand binding domain 2) Hinge region 3) DNA binding domain
What is the pathway of a Seven Transmembrane Domain Receptor (GPCR)?
1) Ligand binds to GPCR, which has stimulatory Gs subunit that binds GTP instead of GDP 2) GTP cause adenylyl cylase to convert ATP to cAMP (second messenger) 3) cAMP triggers protein kinase A signaling cascade
What are 4 types of imaging used in Endocrinology? What do they show?
1) Light microscopy: Cell structure 2) Confocal microscopy: 2D or 3D molecular localization 3) Transmission Electron microscopy: Subcellular structure 4) CAT, MRI, PET scans: 3D structures of hard and soft tissues
What are the 2 treatments for Seasonal Affective Disorder (SAD)?
1) Light therapy 2) Agomelatine: Drug that restores circadian rhythms by acting at melatonin receptors
What are 2 other less mentioned Type 3 tropic hormones?
1) Lipotropin (LPH) 2) Endorphins
What 2 mechanisms are needed to maintain the CL during pregnancy?
1) Luteotrophic hormone (CG) release 2) Lutelolytic hormone (PGF2α) blocked
What 2 enzymes are used in the degradation and metabolism of Catecholamines?
1) MAO: Monoamine oxidase 2) COMT: Catechol-O-methyl transferase
What are the 2 major actions of Aldosterone, a mineralcorticoid?
1) Maintain normal balance of Na+ and K+ in body fluids (mineral balance) 2) Regulate extracellular fluid volume
What are the clinical signs of a 5α-reductase deficiency?
1) Males born with undescended testes, but synthesize testosterone normally 2) Early development of male external genitalia (controlled by DHT) does not take place 3) Infertile
How can Cystic Ovarian Disease (COD) be diagnosed in cattle?
1) Manual palpation or ultrasonography 2) Confirmed with hormone tests
What are the 3 types of Hyperthyroidism?
1) Marine-Lenhart Syndrome 2) Plummer's Disease 3) Graves' Disease
What are 2 examples of Phasic hormone release?
1) Maximum testosterone level in human males occurs between 2 to 6 am 2) Increase in androgens at onset of breeding season in frogs
What are the 2 regions of the Neurohypophysis?
1) Median eminence 2) Pars nervosa
What are the symptoms in behavior of Hypothyroidism?
1) Mental retardation 2) Mentally and physically sluggish, Somnolent (sleepy) 3) Sensitive to cold
How are Radioimmunoassays (RIA) performed?
1) Mix "cold" hormone (unknown sample) and "hot" hormone (known, radioactive sample, different amounts) 2) Hot and cold will compete for binding sites on antibody 3) Measure radioactivity (Detect "hot" only) 4) Compare to estimate "cold"
What is the effect of Polycystic Ovarian Syndrome (PCOS/POD) on the HPG axis?
1) More theca cells: Increased androgens 2) Fewer granulosa cells: Decreased estrogens 3) Less negative feedback from estrogens, progestins
What are the effects of testosterone in men?
1) Muscle mass 2) Skeletal growth 3) spermatogenesis 4) Sexual function
How are thyroid hormones important for nervous system development?
1) Myelin formation 2) Development of intracellular signaling pathways 3) Synapse formation 4) Dendrite growth 5) Nerve cell migration
What are the symptoms in appearance of Hypothyroidism?
1) Myxedema 2) Deficient growth
What is the neurotransmitter control of GnRH release?
1) NE induces GnRH release 2) β-endorphin (or GABA) inhibits GnRH release
What is the neurotransmitter control of Thyrotopin-Releasing Hormone (TRH) release?
1) NE induces production of TRH 2) DA blocks TRH release (Serotonin mixed, but uncertain)
What is the pathway of iodide transport into a thyroid gland follicle cell?
1) Na-I symporter (NIS) actively imports both iodide and Na+ through basement membrane from blood into basal side of follicle cell 2) Pendrin transports iodide through apical portion of follicle cell into colloid
What would occur if a person was given a high exogenous dose of testosterone?
1) Negative feedback on hypothalamus decreasing GnRH production 2) Decreased FSH and LH 3) Decreased LH causes decreased testosterone produced by Leydig cells and no meiosis of germ cells 4) Decreased FSH causes decreased aromatase activity in Sertoli cells
What is the release of hypothalamic regulatory hormones generally controlled by? (2)
1) Neuronal activity 2) Feedback (+/-) from other hormones
What is the pathway of blood and hormones through the Hypothalamo-Hypophysial Portal System?
1) Neurons release releasing hormones into portal system capillaries 2) Portal vessels carry them directly to anterior pituitary 3) Endocrine cells release their hormones into venus portal system for distribution to body
What are 2 types of Neurocrines?
1) Neurotransmitters 2) Neurohormones
What are the 2 types of gaseous bioregulators mentioned?
1) Nitric oxide (NO) 2) Carbon monoxide (CO)
What are 4 reproductive risk factors in cancer development?
1) Nulliparity 2) Delayed first full-term pregnancy 3) Early menarche 4) Late menopause All cause a lengthy exposure of sensitive tissue to cyclical hormone stimulation
What are the 6 steps to the Scientific Method?
1) Observe 2) Formulate hypothesis 3) Conduct experiment 4) Analyze data 5) Report results 6) Re-evaluate hypothesis
How can cell signals be turned off (down-regulation)?
1) Occupied receptors migrate along cell surface to specialized pits involved in formation of endosomes 2) Endosomes fuse with lysosomes which degrade the receptors and ligands
What are the symptoms in behavior of Hyperthyroidism or Graves' disease?
1) Often quick mentally 2) Restless, Irritable, Anxious, Hyperkinetic, Wakeful 3) Sensitive to heat
What are the 2 thyroid gland forms found in vertebrates?
1) One or two masses or glands of vascularized follicles 2) Scattered follicles throughout pharyngeal region
Treatment of both types of cysts of Cystic Ovarian Disease (COD) in cattle is generally the same. What are the treatments?
1) One to two-thirds of cases resolve without treatment 2) At detection, treatment with GnRH followed by prostaglandin (PGF2α) should restore normal estrous cycles within three weeks
What are 4 possible results of receptor activation?
1) Opening/closing of ion channels affecting membrane potentials or secretion 2) Activating or inactivating an enzyme 3) Initiating a series of reactions or cascading events 4) Activating transcription factors that alter gene activity
What are some examples of the Progestin only method of female hormonal contraception?
1) Oral contraceptive pills 2) Mirena intrauterine Device (IUD) 3) Nexplanon/Implanon 4) Depo-Provera 5) Emergency contraception
What are the 2 nuclear receptors that will form heterodimers with thyroid hormone receptors (TR)?
1) Orphan Retinoid X Receptor (RXR) (Mainly) 2) Retinoic Acid Receptor (RAR)
What are the 3 common effects of the Type 2 hormones, GH, PRL, and CS?
1) Osmoregulation 2) Selective tissue growth 3) Lactation
How is the Type 1 hormone FSH involved in gamete preparation in each sex?
1) Ovarian follicle development in females 2) Spermatogenesis in males
What are the symptoms in metabolism of Hyperthyroidism or Graves' disease?
1) Over-eating 2) High basal metabolic rate 3) Increased oxidative enzymes 4) Diarrhea
What are 2 examples of Neurohormones?
1) Oxytocin 2) TRH
Hormonal control of parturition in Cows
1) P4 declines prior to birth 2) Increased cortisol by fetal adrenal gland 3) Prostaglandins (increased by cortisol) facilitate regression of CL, decreasing P4 further
What are 2 actions of the Type 3 Endorphins?
1) Pain killing action discovered after observation of morphine effects 2) Modulate release of other neurotransmitters affecting tropic hormone release
What are the 3 regions of the Adenohypophysis?
1) Pars tuberalis 2) Pars intermedia 3) Pars distalis
What are the 2 type of biological rhythms?
1) Phasic 2) Tonic
What are 2 types of Exocrines or Semiochemicals?
1) Pheromones 2) Allelomones
What are the 2 phases and concentrations of Melatonin's diurnal rhythm?
1) Photophase: Low during the day 2) Scotophase: High at night
What are the 2 types of controls over color change found in animals?
1) Physiological 2) Morphological (Endocrine)
What are 7 effects of the Type 2 fish hormone Somatolactin (SL)?
1) Pigment cells 2) Calcium balance 3) Reproduction 4) Metabolism of phosphate and lipids 5) Correlated with smolting 6) Correlated with gonadal migration 7) Stimulates steroid production (less than FSH)
What are 2 causes of Sexual Precocity (accelerated sexual maturation)?
1) Pineal tumor (25% of cases) secreting gonadotropins (mostly in males) 2) Hypothalamic tumor
What are the 2 forms of Delayed Puberty in females?
1) Primary Amenorrhea 2) Secondary Amenorrhea
Hypothyroidism may be caused at what 2 locations?
1) Primary: At the thyroid 2) Secondary: At the hypothalamus or pituitary
Order of follicular differentiation (5)
1) Primordial follicle 2) Primary follicle 3) Secondary follicle 4) Antral follicle 5) Graffian (mature) follicle
What 2 hormones does the Corpus luteum produce?
1) Progesterone (P4) 2) Estrogen (E2)
What is the result of the cysts formed in Polycystic Ovarian Syndrome (PCOS/POD)?
1) Progesterone and estrogen production declines 2) Lack of negative feedback causes elevation in GTHs 3) GTHs cause production of more androgens, which cannot be converted to estrogens
What are the 4 major classes of Steroids?
1) Progestogens 2) Corticosteroids (Glucocorticoids, Mineralcorticoids) 3) Androgens 4) Estrogens
What are the 3 phases of the Uterine cycle?
1) Proliferative phase 2) Secretory phase 3) Post-luteal or Menstrual phase
What are the 4 endocrine actions of Chorionic Gonadotropin (CG)?
1) Prolong function of CL 2) Stimulate continued production of P4 and E2 by CL 3) Maintain Secretory phase of uterus 4) Block development of other follicles via continued neuroendocrine negative feedback
What are 2 functions of Nitric Oxide (NO) bioregulator?
1) Promotes relaxation of vascular smooth muscle cells 2) May have role in brain: learning and memory
Cyclooxygenase is the first step for the synthesis of what 3 Eicosanoids?
1) Prostaglandins 2) Prostacyclin 3) Thromboxanes
What are the 3 Eicosanoid hormone classes?
1) Prostaglandins (PGs) 2) Leukotrienes 3) Thromboxanes
What 2 things are required to perform a Radioimmunoassay (RIA)?
1) Pure source of hormone being measured 2) Antibody that specifically recognizes that hormone
What are 2 types of Dwarfism?
1) Pygmy peoples of Africa 2) Laron-type Dwarfism
What are 3 Gene Expression approaches used on hormones? What can they test?
1) Quantitative PCR: Single, limited gene sets 2) Microarray: Large gene sets or whole genome 3) RNA Sequencing: Whole genome
What are the 2 types of nuclear receptors that will form Heterodimers with Thyroid Hormone Receptors (TR) inducing transcription?
1) RAR: Retinoic Acid Receptor 2) RXR: Orphan Retinoid X Receptor
What are 3 examples of a Positive Feedback Loop?
1) Rapid influx of sodium to neuron to generate action potential 2) Physiological stress response 3) Induction of sexual maturation 4) Ovulation
What are the 2 fates of Norepinephrine after being released by a neuron?
1) Reabsorbed by emitting cell or target cell 2) Escapes into systemic circulation (small amount)
What are 4 types of Cell-surface Receptors?
1) Receptor Tyrosine Kinases 2) Seven Transmembrane Domain Receptors (GPCR) 3) Cytokine Receptors 4) Ligand-regulated Transporters
What is the pathway of ovarian follicles?
1) Recruitment 2) Selection and dominance 3) Ovulation All occurs with constant atresia of all but dominant ovulatory follicle
What are the 2 fates of cell receptors and ligands after binding?
1) Recycled (up-regulation) 2) Degraded (down-regulation)
What is the treatment of Graves' disease in adults?
1) Reduce thyroid tissue by large dose of radioiodide 2) Surgical removal of portion of thyroid gland
What do the symptoms of Adrenopause include?
1) Reduced libido 2) Depression 3) Loss of skeletal muscle mass 4) Increased body fat 5) Decline in cognitive ability
What are the 3 actions of androgens at the gonad?
1) Regulate Sertoli cell function 2) Stimulate meiosis in primary spermatocytes 3) Required for spermatogenesis
Besides acting in gamete release, what are 2 other functions of LH?
1) Regulation of androgen synthesis 2) Formation of corpus luteum from ruptured ovarian follicles
What 3 things does Atrial Natriuretic Peptide (ANP) inhibit? (each a consequence of the other)
1) Release of Renin from JGA 2) Production of Aldosterone 3) Uptake of Na+ in kidney
What are the 2 major classes of hormones released by the Hypothalamus?
1) Releasing hormones (RH) 2) Release-Inhibiting hormones (RIH)
What is the treatment for Cushing's Disease caused by a pituitary adenoma?
1) Removal of pituitary adenoma (primary) 2) Irradiation therapy for recurrence 3) Complete bilateral adrenalectomy for unsuccessful treatment after recurrence 4) Drug treatment (ketoconazole) to block synthesis of cortisol (ineffective)
Renin-Angiotensin System
1) Renin released by juxtaglomerular apparatus (JGA) cells into glomerulus arteriole 2) Renin interacts with Angiotensinogen to release ANG-I 3) ANG-I travels through venous blood to lungs; Converted to ANG-II by Angiotensin Converting Enzyme (ACE) 4) ANG-II acts at adrenal gland to synthesize Aldosterone from Zona glomerulosa 5) Aldosterone acts at kidney to increase Na+ and H2O reabsorption, increase K+ release into urine 6) Restores normal blood volume/pressure
What are the possible causes of Secondary Amenorrhea?
1) Result of many endocrine disorders (Ex. thyrotoxicosis, drug therapy, premature menopause) 2) Polycystic Ovarian Syndrome (PCOS/POD)
What are the 3 regions of the teleost fish pituitary?
1) Rostral pars distalis 2) Proximal pars distalis 3) Pars intermedia
What are the 2 main Indoleamines?
1) Serotonin 2) Melatonin
What are 3 disorders of the Pineal Gland?
1) Sexual Precocity (accelerated sexual maturation) 2) Circadian Dysrhythmia (jet lag) 3) Seasonal Affective Disorder (SAD)
What are 2 examples of Paracrines?
1) Somatostatin 2) Norepinephrine
What are the 2 hormones involved in GH release and control?
1) Somatostatin (SST); "Breaks" 2) Growth Hormone Releasing Hormone (GHRH)
What are the effects of testosterone's conversion to Estradiol (E2) in men?
1) Spermatogenesis 2) Sexual behavior 3) Bone formation 4) Breast tissue
How are the carbons in Steroids numbered?
1) Start at top carbon of A ring, go around numbering each adjacent carbon of the backbone 2) Don't forget carbons 18 and 19 on the backbone 3) Then number the side chain carbons
Nuclear Receptors mediate the actions of what molecules? (7)
1) Steroid hormones 2) Vitamin D 3) Thyroid hormones 4) Retinoids 5) Fatty acids 6) Eicosanoids 7) Xenobiotics
What are the 7 steps to the mechanism of corticosteroid action?
1) Steroids transported by plasma binding proteins (CBG) in blood 2) Free steroids cross PM (and nuclear membrane) 3) Steroids bind receptors in cytoplasm or nucleus 4) "Zinc-finger" domains revealed 5) Activated complex translocates to nucleus; Forms homodimer 6) "Zinc-finger" domains in DNA-binding region of receptor bind to Hormone Response Elements in promoter region of gene 7) Transcription initiated
What are the 7 steps to the mechanism of sex steroid action?
1) Steroids transported by plasma binding proteins in blood 2) Free steroids cross PM (and nuclear membrane) 3) Steroids bind receptors in cytoplasm or nucleus 4) "Zinc-finger" domains revealed 5) Activated complex translocates to nucleus; Forms homodimer 6) "Zinc-finger" domains in DNA-binding region of receptor bind to Hormone Response Elements in promoter region of gene 7) Transcription initiated
What are the 7 steps to the mechanism of Steroid action?
1) Steroids transported by plasma binding proteins in blood 2) Free steroids cross PM (and nuclear membrane) 3) Steroids bind receptors in cytoplasm or nucleus 4) Steroid receptor activation reveals "zinc-finger domains" 5) Activated complex translocates to nucleus 6) Zinc finger domains in DNA-binding region of receptor bind to Hormone Response Elements in promoter region of gene 7) Transcription initiated
What are the 5 functions of the placenta's secretion of hormones?
1) Stimulate ovarian function 2) Maintain the pregnancy 3) Stimulate function of mammary gland 4) Influence fetal growth 5) Assist in parturition
What is the result(s) of the increased production of Cortisol by the fetal adrenal gland during parturition in cows?
1) Stimulates increased production of Estrogen by placenta 2) Triggers production of Prostaglandins (PGF2α) by placenta
In what 2 ways is GH an anabolic hormone?
1) Stimulates transport of AA into cells 2) Stimulates protein synthesis, especially by skeletal cells
What are the 3 general functions of Prostaglandins (PGs)? (Eicosanoid)
1) Stimulation of smooth muscle contraction 2) Modulation of CNS 3) Stimulation of corticosteroid and testosterone synthesis
Hormonal control of parturition in Sheep
1) Stimulus for birth is marked decrease in P4 2) Sensitizes uterus to Oxytocin 3) Stimulates uterine contractions 4) Fetal adrenal axis also involved
What are the 4 main symptom's of Cushing's Disease?
1) Sudden weight gain 2) Central obesity 3) Glucose intolerance or Diabetes mellitus 4) Purple striae wider than 1cm
What are the treatments of Diabetes insipidus?
1) Sufficient water consumption to offset water loss 2) Vasopressin
How is the circadian rhythm established in the pineal gland?
1) SupraChiasmatic Nucleus (SCN) senses day/night cycle through stimulus from retina 2) Transmits signal through brain and spinal cord to Superior Cervical Ganglion (SCG) 3) Under light conditions, release of NE by SCG is reduced 4) This reduces melatonin production in pineal gland
What are 2 hypothalamic secretory centers you should be familiar with (including abbreviation)?
1) Supraoptic nucleus (SON) 2) Paraventricular nucleus (PVN)
What are the 5 key points of the Resistance Phase of Selye's General Adaptation Syndrome?
1) Sustained release of glucocorticoids 2) Organism adapts to continued stressful stimuli 3) Marked enlargement of adrenal gland (zona fasciculata) 4) After prolonged period, normal functions are impaired 5) Loss of body weight, reproduction, immune suppression
What is the pathway of Thyroglobulin (Tg) synthesis in a cell?
1) Synthesis occurs at Rough ER 2) Tg is packaged into membrane-bound organelles at Golgi 3) Tg packages transported to colloid
What are 3 types of thyroid hormone receptors (TR)?
1) TRα-1 2) TRβ-1 3) TRβ-2
How are thyroid hormones released from thyroid follicles?
1) TSH stimulates engulfment of some colloid by endocytosis forming endosomes 2) Endosomes migrate from apical to basal side of follicular cell 3) Endosomes merge with lysosomes 4) Lysosome enzymes degrade Tg, releasing T3, T4 5) Free thyroid hormones rapidly exit to capillary
What are the therapies for Adrenopause's side effects in men?
1) Targeted therapy (Viagra) 2) Androgen replacement therapy (Questionable due to potential for elevated cancer risk)
Upon differentiation to antral and graafian follicles, the Theca cells form 2 layers. What are these 2 layers and what are their functions?
1) Theca interna: Steroidogenic 2) Theca externa: Connective tissue
What are the 2 major symptoms of Feline Cushing's Disease?
1) Thinning of skin (most obvious) 2) Pigmentation of skin
What are the 3 components to the structure of thyroid follicules?
1) Thyroid epithelium or follicular cells 2) Lumen: Collects protein rich fluid called Colloid 3) Parafollicular cells: Regions between follicles
What 2 factors regulate Non-shivering Thermogenesis?
1) Thyroid hormones 2) Sympathetic nervous system (responsible for maintaining homeostasis)
What are 2 proteins that are attacked by the antibodies involved in Hashimoto's Thyroiditis?
1) Thyroid peroxidase (most common) 2) Thyroglobulin
What are 3 important thyroid hormone transport proteins?
1) Thyroid-Binding Globulin (TBG- carries most) 2) Prealbumin 3) Albumin
What are the 3 Type 1: Glycoprotein hormones?
1) Thyroid-stimulating hormone (TSH) 2) FSH 3) LH
What are the 6 cell types found in the Pars distalis?
1) Thyrotrope 2) Gonadotrope 3) Corticotrope 4) Lactotrope 5) Somatotrope 6) Follicostellate Cell
What hormone changes precede ovulation?
1) Total secretion of GnRH increases, though still pulsatile 2) Surge of FSH and LH
What are the 4 steps to make an active insulin hormone?
1) Translation and translocation 2) Folding, oxidation, and signal peptide cleavage 3) RER export, Golgi transport, vesicle packaging 4) Convertase (protease) cleavage of C-peptide
What is the treatment for Primary Amenorrhea? Can the condition be cured?
1) Treatment of causative disorder 2) Removal of stress (diet, physical, etc.) Treatment usually reverses condition
What are 5 examples of heritable disorders of the reproductive system?
1) Turner's syndrome (XO) 2) Klinefelter's syndrome (XXY) 3) Pure gonadal dysgenesis (XY, or XX) 4) Testicular feminization syndrome 5) 5α-reductase deficiency
What are 3 functional organization types of the Endocrine System?
1) Type 1 2) Type 2 3) Pituitary to target organ
What are the 4 steps in the synthesis of Thyroid hormone up to T4 Thyroxine?
1) Tyrosine incorporated into Thyroglobulin protein (Tgb) within colloid of thyroid follicle 2) Thyroid peroxidase (TPO) adds 1-2 iodine to ring structure to form DIT and MIT 3) Two DIT combine to form T4 Thyroxine 4) Transported via binding proteins to periphery
What is the synthesis pathway of thyroid hormones?
1) Tyrosine is incorporated into Thyroglobulin (Tg) protein within thyroid follicle colloid 2) Thyroid Peroxidase (TPO) adds iodine atom to tyrosine ring structure to form DIT and MIT 3) Two DIT molecules combine to form T4
What are the symptoms in metabolism of Hypothyroidism?
1) Under-eating 2) Low basal metabolic rate 3) Decreased oxidative enzymes 4) Constipation
What are the symptoms/consequences of the androgen buildup caused by Polycystic Ovarian Syndrome (PCOS/POD)?
1) Uterine abnormalities/infertility 2) Amenorrhea 3) Hirsutism (occasional balding)
What are the 2 classes of Nonapeptides found and stored in the Pars nervosa?
1) Vasopressin-like peptides 2) Oxytocin-like peptides
What are the symptoms in muscle function of Hyperthyroidism or Graves' disease?
1) Weakness 2) Fibrillary twitchings, tremors
What are the symptoms in muscle function of Hypothyroidism?
1) Weakness 2) Low muscle tone
What are the typical symptoms of Hypothyroidism in dogs?
1) Weight gain 2) Lethargy 3) Poor hair coat (course hair) 4) Poor appetite 5) Hair loss 6) Increased skin, ear infections
What are 5 possible side effects of Prednisone (glucocorticoid) use?
1) Weight gain 2) Worsening diabetes 3) Promotion of cataracts in eyes 4) Thinning of bones (osteopenia and osteoporosis) 5) Increased risk of infection
What are the typical signs of Hyperthyroidism in cats?
1) Weight loss 2) Increased appetite 3) Hyperactive, high energy 4) Increased thirst, urination 5) GI distress 6) Loose stools 7) Anxiety, restlessness 8) Fast respiration, panting 9) Changes in skin, hair coat
What are 4 defining characteristics of Protein-secreting Cells?
1) Well-developed RER 2) Mitochondria have plate-like cristae 3) Well-developed Golgi apparatus 4) Protein stored within and readily available
How does one "map" a homeostasis pathway? (8)
1) What information drives the system? 2) What are the receptors? Where are they located? 3) What input is generated by the information stimulus and how is it sent to the controller? 4) What is the controller? Where is it located? 5) What is the set point? 6) What output is generated by the controller? 7) What are the effectors? What effects are produced? 8) What is the resulting change in the system? How does it feedback to the receptor?
What are 4 functions of the Endocrine System?
1) Works in coordination with other physiological systems (i.e. nervous, immune, digestive) 2) Regulates development, growth and metabolism 3) Responds to stress and injury 4) Homeostasis
What are the 3 "zones" of endocrine tissues of the Adrenal Cortex?
1) Zona glomerulosa 2) Zona fasciculata 3) Zona reticularis
What are 2 important 2nd messengers?
1) cAMP 2) Ca²⁺
What are 4 examples of Intracrines?
1) cAMP 2) IP3 3) Calmodulin 4) Ca²⁺
When the small peptide of Adrenocorticotropin (ACTH) is split, what are the 2 molecules formed? Which has overlap in biological activity with Adrenocorticotropin (ACTH)?
1) α-MSH: Overlap in activity 2) CLIP
What are 2 examples of Thyroid Transport Proteins (binding) that transport T4 in the blood?
1) α2-globulins 2) Prealbumin
What are 2 examples of Thyroid Transport Proteins used to transport T4 in the blood?
1) α2-globulins 2) Prealbumin
What is the active form of Vitamin D?
1,25-DHC
Corticotrope: Cell frequency
10-15%
How many women of reproductive age does Polycystic Ovarian Syndrome (PCOS/POD) affect?
10-15%
Lactotrope: Cell frequency
10-25%
17α-hydroxyprogesterone (C21) + 21α-hydroxylase =
11-Deoxycortisol (C21): Hydroxyl at C21 on side chain
Deoxycorticosterone (C21) + 17α-hydroxylase =
11-Deoxycortisol (C21): Hydroxyl group to C17
The number of ovulated oocytes differs among species, but ovulation will typically occur within ______ hours post LH surge.
12-24 hours
Gonadotrope cell type: Cell frequency
15-20%
What is the percentage of T3 produced by the thyroid glands? T4?
15-50% (Less); 50-85% (More)
How many carbons make up the Steroid base structure?
17 carbons
How many carbons are found in a steroid structure?
17-27 carbons
Pregnenolone (C21) + 17α-hydroxylase = ______
17α-Hydroxypregnenolone (C21): Hydroxyl group to C17
Progesterone (C21) + 17α-hydroxylase = ______
17α-hydroxyprogesterone (C21): Hydroxyl group to C17
17α-Hydroxypregnenolone (C21) + 3β-HSD =
17α-hydroxyprogesterone (C21): Ketone on C3
Which is more common, 17β-Estradiol or 17α-Estradiol?
17β-Estradiol
How many carbons do Steroid Estrogens have?
18
When was the iodine-containing compound discovered in the thyroid gland?
1896
How many carbons do Steroid Androgens have?
19
When was the T4 thyroid hormone first discovered?
1915
When was T3, the bioactive thyroid hormone, identified?
1952
Cretinism affects ___ in ___ births.
1; 8500
How many adrenal glands do most mammals have?
2 (paired structure)
How many additional carbons are attached to the rings in the Steroid base structure?
2 carbons (Plus rings= 19)
Type 1: Glycoproteins (TSH, LH, FSH, CG)
2 peptide chains, α-subunit and β-subunit; Specific carbohydrates attached
How many carbons do Steroid Corticosteroids (Glucocorticoids, Mineralcorticoids) have?
21
How many carbons do Steroid Progestogens have?
21
How many chromosomes are found in secondary spermatocytes, spermatids, and spermatozoa?
23
How many carbons does Cholesterol have?
27
How many types of Lactotropes are produced in Pars distalis? How are they different?
2; Based on shape
The adrenal gland consists of ___ distinct regions with differing ______.
2; Functions
How many types of Metabolism is their of Steroid hormones?
2; Phase 1 and Phase 2 metabolism
How many regions does the teleost fish pituitary have?
3
What is the Type 1 hormone FSH's half-life?
3 hours
T3- Triiodothyronine (STRUCTURE)
3 iodines
What is the number of iodine atoms found in T3? T4?
3; 4
How many forms of GnRH exist in the body?
3; GnRH-1 (hypothalamic), GnRH-2, GnRH-3
What enzyme can convert several ∆5-pathway steroids into ∆4-steroids?
3β-HSD
The adrenal gland contains ___ types of endocrine tissues, each with specific characteristics.
4
How many functional gametes are produced by Spermatogenesis of one spermatogonium?
4 functional gametes
T4- Thyroxine (STRUCTURE)
4 iodines
What does the base structure of a Steroid include?
4 joined cycloalkane rings: 3 cyclohexane (A-C); 1 cyclopentane (D)
What is the secretion pattern of GnRH (and FSH/LH by association)?
4 to 8 pulse episodes in 24 hour cycle
How many chromosomes are found in Spermatogonium and primary spermatocytes?
46
How many distinct nuclear receptor genes are found in humans?
48 (numbers differ moderately among species, new variants discovered)
Normally, there is much more circulating T__ than T__.
4; 3
What is the potency of T3? T4?
4x more than T4; Not potent
Concerning an idiopathic cause of Precocious Puberty, how old was the youngest mother on record?
5 years old
Rates of Cystic Ovarian Disease (COD) in a herd of cattle are generally ____%, but can sometimes reach as high as ___%.
5-10%; 30%
Their are ___ nonapeptides identified in the Pars nervosa, but not all are found in all ______.
5; Mammals
How many asymetric carbons are present in Steroids?
6 (Carbon 3, 5, 11, 16, 17, 20)
The Neurohormones associated with the Pars nervosa all have a similar structure. What is this structure?
9 amino acid residues= Nonapeptides
What is the general structure of Catecholamines?
A catechol attached to an amine side group
What action does ACTH induce in the Adrenal Cortex's Zona fasciculata?
ACTH induces hypertrophy (cell size) and hyperplasia (# of cells)
______ acts on the ______ to produce the Glucocorticoids Cortisol and Corticosterone.
ACTH; Zona fasciculata (ZF)
______ acts on the ______ to produce DHEA (adrenal androgens).
ACTH; Zona reticularis (ZR)
______ acts on the ______ to produce Aldosterone.
ANG-II; Zona glomerulosa (ZG)
What is the half-life of circulating T3?
About 24 hours
What is the half-life of circulating T4?
About 7 days
How large is the Pineal gland in humans?
About the size of a grain of rice
What is the cause of Diabetes insipidus?
Absence of arginine vasopressin (AVP) (Half of cases are idiopathic)
There is a difference in ______ and ______ of granules between gonadotrope and corticotropes and other tropic cells.
Abundance; Size
How do thyroid hormones cause a thermogenic effect specifically? What is the result of this?
Accelerate rate of glucose oxidation (↑metabolic heat); Increased basal metabolic rate, measured by increased rate of oxygen consumption
Acetylcholine acts via _____ (______) receptors.
Acetylcholine (Cholinergic)
Some hypothalamic regulators include neurotransmitters such as: (5)
Acetylcholine, dopamine, norepinephrine, serotonin, GABA
What is Acetylcholine degraded by? Where?
Acetylcholinesterase (AChE); At post-synaptic cell membrane
Neurotransmitters
Act directly on next cell (paracrine activity); In response to stimuli, neurons release chemicals (neurotransmitters) that act on cell at axon terminus
Seven Transmembrane Domain Receptors
Activated by Catecholamines, Prostaglandins, ACTH, glucagon, TSH; G-protein coupled
Receptor Tyrosine Kinases
Activated by growth factors and insulin; Activation triggers tyrosine kinase activity on intracellular domain
What is the action of Type I Deiodinase? In what tissues is it expressed?
Activates T4 to yield T3, Inactivates T4; Liver, Kidney
What is an example of the activation of hormone receptors triggering the SYNTHESIS of a second messenger molecule?
Activation of G protein-coupled receptors (GPCR) triggers synthesis of cAMP
What kind of transport is iodide transport into the colloid in follicles of the thyroid gland? What does it require?
Active transport; Energy (Energy-dependent)
Smolt salmon
Active, silvery markings, capable of osmoregulation in seawater
Aldosterone synthase
Adds double-bonded O to methyl group at C18
11β-hydroxylase
Adds hydroxyl group to C11 in beta orientation
17α-hydroxylase
Adds hydroxyl group to C17 in alpha orientation
21α-hydroxylase
Adds hydroxyl group to C21 in alpha orientation
Where are Leydig cells located?
Adjacent to seminiferous tubules in interstitial space
What adrenal tissue and hormones are involved in Long-term, chronic stress response?
Adrenal Cortex; Glucocorticoids, Mineralcorticoids
What adrenal tissue and hormones are involved in Short-term, acute stress response?
Adrenal Medulla; Catecholamines Epinephrine and Norepinephrine
What hormone is synthesized in the Zona reticularis of the Adrenal Cortex?
Adrenal androgen DHEA
What is the primary steroid made by the Zona reticularis, and the fetal zone in primates?
Adrenal androgen DHEA
Zona reticularis: Hormones produced; Regulation
Adrenal androgens DHEA; Regulated by ACTH, some unknown factors
What endocrine tissue is organized into folded sheets or cords?
Adrenal cortex
Where are Corticosteroids produced?
Adrenal cortex
Where does the ∆5-pathway typically occur in the body? What does it typically stop with?
Adrenal cortex; DHEA
Corticotrope: Hormone secreted
Adrenocorticotropic hormone (ACTH)
Hormones typically have high ______ for specific hormones. What does this mean?
Affinity; A strong tendency to interact or bind (good fit)
Cross Talk can be either ______ or ______.
Agonistic (Cooperative); Antagonistic (Countermand)
What is the general function of Luekotrienes? (Eicosanoid)
Aid in inflammatory response
What hormone is synthesized in the Zona glomerulosa of the Adrenal Cortex?
Aldosterone
What is an example of Steroid Mineralcorticoids?
Aldosterone
What is the 1 Mineralcorticoid?
Aldosterone
What is the primary steroid made by the Zona glomerulosa?
Aldosterone
Corticosterone (C21) + Aldosterone synthase = ______ Corticosterone (C21) + 17α-hydroxylase = ______
Aldosterone (C21): Double-bonded O to methyl group at C18 Cortisol (C21): Hydroxyl group to C17
What hormone's synthesis, besides glucocorticoids, is also impaired by the genetic defects that cause Congenital Adrenal Hyperplasia (CAH)? What is the result of this impairment?
Aldosterone (because Aldosterone forms from glucocorticoids); Na+ and K+ imbalance
What is Hyperaldosteronism caused by?
Aldosterone-producing adenoma or carcinoma in Zona glomerulosa
Zona glomerulosa: Hormones produced; Regulation
Aldosterone; Regulated by Renin-Angiotensin System
In what animals does Vitellogenesis occur?
All egg-bearing non-mammals
What is the result of all the therapies for Graves' disease?
All function to reduce thyroid hormone production and alleviate symptoms of hyperthyroidism, but none address the cause, LATS production by immune system
There are many types of Thyroid Hormone Receptors (TR). Where are TRα-1 and TRβ-1 receptors found?
All tissues
The well known odor released by skunks is an example of what type of bioregulator?
Allelomones
What does the regression of the Corpus luteum allow?
Allows for resumption of regular GnRH release and secretion of FSH/LH for next cycle
Catecholamine: Norepinephrine (KNOW STRUCTURE)
Amine chain with hydroxyl
Catecholamine: Epinephrine (KNOW STRUCTURE)
Amine chain with hydroxyl and additional methyl group
What category of bioregulator are most neurotransmitters, neurohormones and classical hormones?
Amino acids, peptides and proteins
GH is a(n) ________ hormone.
Anabolic
What hormone are Peritubular Myoid cells under the influence of?
Androgens
What stimulates the release of Inhibin in males?
Androgens
What do Leydig cells produce? In response to what hormone?
Androgens (testosterone, DHEA, androstenedione); LH
What is responsible for sexual dimorphisms in the brain?
Androgens secreted early in development
Estrogens can ONLY be formed from ______.
Androgens- Exogenous or Endogenous
What is 1 example of Pheromones?
Androstadienone
What is the end substrate in the ∆5-pathway?
Androstenediol (C19)
Dehydroepiandrosterone (DHEA) (C19) + 17β-HSD = ______
Androstenediol (C19): ∆5-pathway; C17 ketone converted to hydroxyl
17α-hydroxyprogesterone (C21) + 17,20 lyase = ______
Androstenedione (C19): Ketone formed instead of side chain
In most cases of Cystic Ovarian Disease (COD) in cattle, the cows are ______.
Anestrous
ANG-II
Angiotensin II; Formed by conversion of ANG-I by ACE in lung endothelial cells; Stimulates synthesis of Aldosterone
Photoperiodic breeding pattern
Animals breed based solely on photoperiod cues
Photorefractory breeding pattern
Animals respond to changes in photoperiod only at certain times; Means changing photoperiod won't change the breeding cycle
In what animals are major effects of pineal function observed in?
Animals that have seasonal breeding in spring or fall (Breeding linked to changes in length of photoperiod, and thus duration of melatonin release)
Primary Amenorrhea is a common side effect of what disorder? What hormonal changes do patients suffer from?
Anorexia nervosa; Depressed LH, FSH
Cystic Ovarian Disease (COD)
Anovulatory fluid-filled structures of >25mm diameter for more than 10 days
Thyrotrope: Distribution
Anterior medial
Neurohypophysis: Median eminence
Anterior portion of pituitary; Some consider subdivision of hypothalamus; Common blood supply with Adenohypophysis
What is the treatment of Graves' disease in children and adolescents?
Anti-thyroid drugs
Hashimoto's Thyroiditis
Antibodies attack proteins involved in thyroid hormone synthesis
Enzyme-Linked Immunoabsorbant Assay (ELISA)
Antibody detection of specific hormones in biological samples (e.g. blood plasma); Uses two antibodies Primary Ab is specific to target Secondary Ab targets primary Ab Detection by colorimetric method
What are Vasopressins primary function? How?
Antidiuretic agents; Increases kidney's ability to reabsorb water from glomerular filtrate thus reducing urine volume
Pendrin
Apical transport of iodide into colloid
What is the aspect of experiment design that trips up most young scientists?
Appropriate experiment controls
What is the precursor to all Eicosanoids?
Arachidonic acid (AA)
Estrogen synthesis requires what enzyme activity?
Aromatase
What is involved in establishing masculinization of the hypothalamus in rodents; not clear in humans?
Aromatase conversion of testosterone to estrogens
How does an Antral follicle form?
As the follicle grows, Granulosa cells secret antral fluid, an ultra-filtrate of blood plasma, into the follicular antrum
What are some regions of the world that have very poor iodide availability?
Asia, Africa, South America
Most follicles that are grown during a given cycle will undergo apoptosis and degenerate, a process called ______.
Atresia (programmed cell death)
When can atresia occur in follicle development?
Atresia can occur at any stage of follicle development
What is the impact of Addison's Disease on the adrenal glands?
Atrophied, non-functional; Not capable of responding to ACTH
What hormone type is secreted by non-neuronal cells into surrounding extracellular fluid and acts on the emitting cell?
Autocrine
There is a ______ control by GnRH on its own release.
Autocrine; GnRH secreting cells have GnRH receptors
What is the most common cause of thyroid disease in dogs? (90% of cases)
Autoimmune Thyroiditis (type of Hypothyroidism)
What causes Graves' disease, which is an autoimmune disease?
Autoimmune disease causes the antibody LATS to develop which trigger TSH receptors; Results in chronic stimulation of thyroid to produce thyroid hormones
The iodine content reflects local and regional _______.
Availability
Alpha (α) spatial conformation
Away from you (Hatched wedge); Behind the plane
Homeostasis
Balance of physiological systems operating within the organism to maintain a dynamic equilibrium; Relatively constant steady state maintained within certain tolerable limits
How do the Basal and Functional layers of the Endometrium form?
Basal layer proliferates during each uterine cycle to produce inner Functional layer that either regresses or is shed (menses)
Na-I Symporter (NIS)
Basal transport of iodide
How are Eicosanoids categorized?
Based on different functional groups on 5-carbon ring
How do specific steroids vary?
Based on functional groups attached to base structure (steroid nucleus) and on the side chain structure
High Performance Liquid Chromatography (HPLC)
Based on principals of column chromatography; Takes advantage of chemical characteristics (different solubility) to separate compounds that are closely related
How is the HPA axis affected by the stress response in captive birds vs. free-ranging birds?
Baseline cortisol levels and stress response are depressed in captive birds compared to free-range, therefore they have reduced reproductive performance
When do estrous cycles typically begin and end?
Begin at puberty; Typically continue until death or interruption due to pregnancy or Anestrous phase; There is an exception in cessation of menstrual cycles in humans due to menopause
Selye's General Adaptation Syndrome: Resistance Phase
Begins if stress lasts longer than few hours; Glucocorticoids are dominant hormones, shifting tissue metabolism away from glucose increasing availability to brain
Cytokine Receptors
Bind signaling molecules such as Tumor Necrosis Factor Alpha (TNFα), leptin, growth hormone; Associate with intracellular tyrosine kinases
What is the receptor action of the Type 2 hormone PRL?
Bind to Cytokine-type receptor, which is phosphorylated by JAK at target cells
Ligand-regulated Transporters
Bind to ligands such as acetylcholine; Response opens ion channel; Ion flux acts as messenger molecule
How do Thyroid hormones act?
Bind to nuclear receptors to drive transcription
What is the receptor action of all Type 2 hormones, GH, PRL, and CS?
Bind to single cytokine-type transmembrane domain receptors; Receptor dimerizes, then activates kinase cascade via JNK signaling
Down-regulation of the receptor typically occurs after ligand ______, and may be followed by ______ of receptors on the cell surface called ______.
Binding; Re-expression; Up-regulation
What is Vasopressin's (AVP) specific action at the kidney?
Binds PM receptor triggering synthesis of cAMP leading to both 1) phosphorylation/activation of aquaporins 2) synthesis of more aquaporins, with net result of more water influx into cell
What is the receptor action of the Type 3 hormone Melanotropin (α-MSH)?
Binds to Melanocortin 1 Receptor 1 (MSH receptor); GPCR present on melanocytes in skin
What is the receptor action of the Type 3 hormone Adrenocorticotropin (ACTH)?
Binds to Melanocortin 2 Receptor (ACTH receptor); a 7-transmembrane, GPCR
In Type 3 hormones, there is some overlap in ________ due to ______.
Biological activities; Structural similarities
What should be kept in mind when interpreting hormone data?
Biological rhythms
What is an example of a Negative Feedback Loop?
Blood glucose
The Vasopressin-like peptides found in the Pars nervosa are important in ______.
Blood pressure regulation
The 2 regions of the Neurohypophysis, the Median eminence and Pars nervosa, have separate ______ from each other.
Blood supplies
Where are Neurohormones found (compartment)? What is their target?
Blood, CSF; Any cell type
Where are Hormones found (compartment)? What is their target?
Blood; Any cell type
Amino acids, amines, peptides and proteins are soluble in ______ and ______, but cannot easily pass through ______.
Blood; Interstitial fluids; Plasma membrane
Cytocrines (Autocrines, Paracrines) do not enter ______.
Bloodstream (work proximally)
What denotes the number of receptors or binding sites?
Bmax
Much of the timing of puberty has to do with ______.
Body weight
Adrenal Cortex: Zona reticularis
Borders adrenal medulla; Primary site of adrenal androgen synthesis: DHEA; Connective tissue elements, reticular fibers
How are Ligand-Receptor Assays similar to RIA?
Both use radioactively-labeled hormones to compete for binding sites and estimate non-specific binding
Where are Neurosteroids produced?
Brain
In what tissues is Type III Deiodinase expressed?
Brain, placenta, intestine, fetal tissue
17,20 lyase
Breaks bond between C17 and C20 leaving ketone at C17
Gonadotrope: Distribution
Broad
Lactotrope: Distribution
Broad, near gonadotropes
What is the result of Glucocorticoids' (cortisol) blocking of glucose utilization?
By blocking glucose utilization, glucocorticoids spare blood glucose leaving a preferential supply for the brain
At what carbon does the Steroid side chain branch from?
C17
Estrogens: 17β-Estradiol (E2) (Structure)
C18; No side chain, only C17 Hydroxyl; Aromatic A ring with hydroxyl (phenol group)
Androgens: Testosterone (T) (Structure)
C19; No side chain; C17 Hydroxyl; 1 DB in rings
Corticosteroids: Cortisol (F) (Structure)
C21; Hydroxyl at C17 and on ketone side chain; 1 DB in rings
Progestogens: Progesterone (P4) (Structure)
C21; Ketone side chain; C3 ketone in A ring; 1 DB in rings
Cholesterol (Structure)
C27; Hydroxyl on A ring; Long unsubstituted side chain
______, with high similarity to C-terminal portion of Adrenocorticotropin (ACTH), but has no similar biological activity.
CLIP
GABA (Gamma-AminoButyric Acid) bioregulator
CNS Neurotransmitter with inhibitory actions
Type 1 Endocrine System
CNS regulates hormone release from brain, which stimulates pituitary production of tropic hormones, which act on peripheral endocrine glands, which release hormones to target organs and provide feedback to the brain and hypothalamus
What molecule binds to 4 cytosolic Ca²⁺ thus starting a kinase signaling cascade?
Calmodulin (regulates wide variety of cellular proteins)
How and when does Graves' disease typically appear?
Can appear suddenly; Usually later in life
The follicles found in the thyroid gland have both ______ and ______.
Capillaries; Innervation
What is the outer covering of the adrenal gland called?
Capsule
Rete testis
Carry mature sperm from Seminiferous Tubules to efferent ducts
What is the recommended treatment for Cryptorchidism in dogs? Why?
Castration; Increased risk of testicular cancer in retained testis (particularly Sertoli cell cancer)
Haloperidol, Isoproterenol, Ephedrine, Amphetamine, and LSD are agents that alter what hormone activity?
Catecholamine and Indoleamine
What hormones are released by the Adrenal Medulla?
Catecholamines: Epinephrine and Norepinephrine (Neurohormones released by hypothalamic neuronal direction)
Adrenal Medulla (chromaffin cells): Hormones produced; Regulation
Catecholamines: Epinephrine, Norepinephrine; Regulated by Sympathetic Nervous System
What is unique about maternal recognition of pregnancy in cats and dogs?
Cats and dogs don't require maternal recognition of pregnancy, the normal luteal phase lasts the entirety of the pregnancy
Myoepithelial cells
Cause milk ejection from Alveoli into duct system
What is a second function of Vasopressins besides acting as antidiuretic agents?
Cause vasoconstriction and blood pressure elevation (pressor effect)
What causes laron-type dwarfism?
Caused by mutation in GH receptor; Liver is unresponsive to GH and doesn't produce IGF, thus normal GH, but very low IGF levels (important in GH action)
Cushing's Disease
Caused by pituitary adenoma (benign tumor of glandular origin)
What does Carbon Monoxide (CO) bioregulator have to do with cell stress?
Causes small amounts of stress to prepare cell for any additional major stress
Each of the 3 regions of the teleost fish pituitary have distinct _____ that produce different _____.
Cell structures; hormones
Amine and peptide hormones, since they cannot easily pass through the plasma membrane, bind to _____ receptors.
Cell-surface
Adrenal Cortex: Zona glomerulosa
Cells are smaller, more rounded, less lipid; Don't change in response to ACTH (permissive effect)
How does high TSH affect thyroid gland morphology? (Ex. Intensive TSH treatment)
Cells become enlarged, proliferate (hypertrophy, hyperplasia); Lumen is reduced
How do thyroid hormones cause a thermogenic effect generally?
Cells consume more energy resulting in increased heat generation
How does a lack of TSH affect thyroid gland morphology? (Ex. pituitary removal)
Cells lose cuboidal shape, appear flat; Lumen is expansive
Endocrine
Cells respond to factors (hormones) produced by distant cells that travelled through the blood
How is the Surge center different in some species compared to humans?
Center is anatomically separated (rodent)
Reproduction is influenced by environmental factors that are perceived and integrated by the ______.
Central nervous system (CNS)
Corticotrope: Distribution
Central wedge
Exposure to endocrine disrupting chemicals cause of Precocious Puberty
Certain industrial chemicals (phthalates and bisphenol A in plastics) have been shown to cause early puberty in laboratory animals; Fairly strong evidence in wildlife, especially fish/amphibians
Gonadal steroid cause of Precocious Puberty
Certain ovarian or testicular tumors secrete sufficient excess steroids to cause external evidence of puberty, though the gonads are still quiescent (no gamete production)
What hormonal changes occur to facilitate uterine contractions in humans?
Change in E2/P4 ratio triggers production of more oxytocin receptors in myometrium to facilitate uterine contraction
How does cortisol function in the adaption to the external environment for migrating salmon?
Change in water salt concentration triggers cortisol release; Cortisol returns to basal levels after fish adapts to new environment, although salmon do NOT adapt and results in exhaustion
What are the changes in Melatonin levels a result of?
Changes in activity of rate limiting enzyme, N-acetyltransferase NAT
Unoccupied Steroid receptors are associated with molecular ______ proteins. What happens to these proteins once the steroid binds and the receptors are phosphorylated?
Chaperone proteins; Chaperones are released exposing DNA-binding domain or "zinc-fingers"
Hormones
Chemical messengers that act on target cells or organs; From hormon, meaning to stimulate or excite (signal a target cell to do something)
Exocrines or Semiochemicals
Chemicals released by an organism that effect the behaviors of other individuals
When and where was thyroid disease first described? What were the remedies at the time?
China, 3000 B.C.; Seaweed, burned sponge, desiccated deer thyroids
What are all vertebrate Steroid hormones synthesized from or their parent compound?
Cholesterol (C27)
What is Acetylcholine synthesized from?
Choline and Acetate by choline acetyl-transferase (CAT)
The structures and biological activity of certain ______ hormones are similar to ______-derived counterparts.
Chorion; Pituitary
How does the mother "sense" or recognize that she is pregnant?
Chorionic Gonadotropin (CG) production
During the last trimester, the placenta also makes an additional hormone. What is it called?
Chorionic Somatomammotropin (CS) or Placental lactogen
What is the 1 Type 3: Smaller peptide Placental (chorionic) tropic hormone?
Chorionic corticotropin (CS)
What is the 1 Type 2: Long peptide chain Placental (chorionic) tropic hormone?
Chorionic somatomammotropin (CS)
What type of cells are found in the adrenal gland's Adrenal medulla?
Chromaffin cells
What are the cells of the Adrenal Medulla called? Why?
Chromaffin cells; Due to dark staining with chromic acid
What causes the release of Atrial Natriuretic Peptide (ANP)?
Chronically elevated blood volume and/or pressure stretching the heart atria
What is the main feedback signal in Thyroid-stimulating hormone (TSH) secretion caused by? What kind of feedback is it?
Circulating T4; Negative feedback
Nonapeptides are released from axon endings directly into ______ in response to neural stimulation, with some targets at a considerable distance (kidney, mammary gland, uterus).
Circulation
Where does the P450 side chain cleavage enzyme (P450SCC) cleave on Cholesterol?
Cleaves at C20-C22 bond to remove side chain
Teleost fish: Pars intermedia
Closely connected with Pars nervosa; Direct innervation responsible for directing α-MSH secretion
Adrenocortical cells are ______ in most species, but locus differs with respect to kidney and the chromaffin cells.
Co-located (paired)
There is greater thyroid activity during prolonged periods of ______
Cold stress (seasonal)
Where are mature sperm collected after being produced? Where are they then stored?
Collected in ducts of rete testis; Stored in epididymis
Thyroiditis
Collection of gene-linked autoimmune disorders causing inflammation of thyroid gland
Where is Thyroglobulin (Tg) found?
Colloid structure within thyroid follicle
Where is thyroglobulin (Tgb) for Thyroid hormone synthesis found?
Colloid structure within thyroid follicle
What is the milk produced at or near birth called? How is it different?
Colostrum; Contains increased immunoglobulins, carbohydrates, and fats
Cryptorchidism (Undescended testes)
Common at birth, and much lower at 1 year of age; Low occurrence in adults; Unilateral cryptorchidism is more common than bilateral
Endocrine System
Complex regulatory system that controls the flow of information between different cells and tissues
Mass spectrometry (MS)
Compound identification by mass spectra; Able to accurately measure multiple chemicals at very low concentrations from single sample
What can very large Goiters result in?
Compression of trachea, possibly resulting in difficulty breathing, swallowing
Cretinism
Condition in children; Severe growth impairment due to Hypothyroidism
Hyperadrenocorticism (HAC)
Condition in which the adrenal gland produces glucocorticoids in excess
Milk ejection is also subject to classic ______ response. What does this mean?
Conditioning; 1) Stimulation of milk flow in cows by observation of sights and sounds of milking parlor 2) Milk flow stimulated in women at sound of infant crying
Phase 2 Metabolism of Steroid hormones
Conjugation (addition) with other molecules, inactivating steroid, and targeting it for excretion by making it water-soluble; Ex. glucuronidation, sulfonation
Infundibulum
Connective stalk between Hypothalamus and Pituitary
The fundamental structure of the thyroid is ______ in vertebrates.
Conserved
What causes an alcohol hangover?
Consumption of alcohol in large quantities suppresses AVP, leading to diuresis and excessive dehydration
Epididymis
Contains efferent ducts to collect mature sperm; 3 sections: Head, Body, Tail
Patterns of hormone release: Tonic
Continuous and constant
Some steroidogeneic cells of atretic follicles remain active. What are these cells' function?
Contribute to interstitial gland of ovary; Produce androstenedione in response to LH contributing to synthesis of E2 by Granulosa cells
Reference Control
Control that is used as a constant and unchanging standard of comparison; Usually in environmental or epidemiology study
What is the Tonic center controlled by?
Controlled by cycling changes in intracellular calcium concentration
In all vertebrates, whose control over color change is Morphological (Endocrine), what is α-MSH's role in that control?
Controls the NUMBER of chromatophores and the AMOUNT of pigment contained within
What enzyme cleaves off the C-peptide connecting sequence found in the insulin prohormone?
Convertase
What happens to excess Cholesterol that is not used in the synthesis of Steroid hormones?
Converted to bile salts in the liver for excretion
What is the action of Type II Deiodinase?
Converts T4 to T3; Major source of cytoplasmic T3
17β-HSD
Converts β hydroxy group at C17 to ketone; Reversible
3β-HSD (hydroxysteroid dehydrogenase)
Converts β hydroxy group at C3 to ketone
What are the degenerating follicles undergoing atresia called?
Corpora atretica
Following ovulation, the follicle remnants differentiate into the ______.
Corpus luteum
Luteal phase of estrous cycle
Corpus luteum is dominant structure; Post-ovulation
How long does the Corpus luteum last in dogs, pigs, and rabbits? Why?
Corpus luteum is required throughout the entire pregnancy; Short pregnancies
If pregnancy occurs, what structure is critical to continued pregnancy? Why?
Corpus luteum; Needed to maintain production of Progesterone and maintain endometrium (Secretory phase)
Deoxycorticosterone (C21) + 11β-hydroxylase = ______
Corticosterone (C21): Hydroxyl on C11
What is the main stimulatory hormone involved in the regulation of Adrenocorticotropin (ACTH)? What is its structure?
Corticotropin-Releasing Hormone (CRH); Neuropeptide
11-Deoxycortisol (C21) + 11β-hydroxylase =
Cortisol (C21): Hydroxyl on C11
What is an example of Steroid Glucocorticoids?
Cortisol (F)
In patients with Cushing's Disease, what will be their Cortisol and ACTH levels before a DEX test? After the DEX test?
Cortisol before: High ACTH before: High Cortisol after DEX: Low; Because DEX overcomes refractory nature of pituitary tumor ACTH after DEX: High
What are the 2 main Glucocorticoids?
Cortisol, Corticosterone (also Deoxycorticosterone, 11-Deoxycortisol)
What are some examples of animals that are polyestrus?
Cows, pigs, rodents
Why are IGFs critical in GH action?
Critical for mediating effects of GH on protein synthesis, amino acid transport, and lipolysis
What is one cause of Delayed Puberty in males?
Cryptorchidism (Undescended testes)
Can Cushing's Disease be cured in horses?
Currently no methods of removing or attenuating growth of pituitary adenomas; Tumor will grow until it compromises quality of life
What is one of the most common endocrine disorders in horses?
Cushing's Disease
In a High Dose DEX Test, what does Low Cortisol (with high DEX) and High ACTH indicate?
Cushing's Disease; Pituitary is refractory to DEX
What is the first step in Eicosanoid synthesis of Prostaglandins and Thromboxanes?
Cyclooxygenase of Arachidonic acid
What is the condition that is similar to Polycystic Ovarian Syndrome (PCOS/POD) found in cattle?
Cystic Ovarian Disease (COD)
What cells do the cysts of Polycystic Ovarian Syndrome (PCOS/POD) develop from?
Cysts develop from thecal cells, and proportionally fewer granulosa cells
Autocrines and Paracrines are ______.
Cytocrines (local hormones)
Cytokine Receptors react to ______ and act ______.
Cytokines; Locally
In patients with Cushing's Disease, what is the result of the high dose DEX test?
DEX fails to suppress cortisol production because the pituitary (pituitary tumor) is refractory to DEX
How is Cushing's Disease detected in horses?
DEX suppression test
Why is the Fetal Zone's production of the adrenal androgen DHEA important?
DHEA is required as a precursor for estrogen synthesis by the placenta, which is incapable of androgen synthesis; Without the Fetal Zone and DHEA, pregnancy would fail
What is responsible for increased hair loss? How?
DHT; Blocks proteins/vitamins from access to hair follicle, reducing follicle size
______ has higher affinity for androgen receptors than ______.
DHT; Testosterone
What do Physiological color changes involve?
DISPLACEMENT of pigment granules within a chromatophore, rather than change in number and amount of pigment like Morphological (Endocrine) color changes
What is the primary peptide and protein structure encoded by?
DNA
What is 1 way that hormones can be studied using Molecule interactions?
DNA/protein interactions via Chromatin ImmunoPrecipitation (ChIP)
Chorionic Somatomammotropin (CS) or Placental lactogen is made by some species, but not all. What species produce CS? Which do not?
DO: Primates, rodents, sheep DON'T: Dogs, rabbits
What kind of cattle does Cystic Ovarian Disease (COD) primarily affect? Why could this be?
Dairy cows (as many as 1 million in U.S.); Due to negative energy balance
17α-Hydroxypregnenolone (C21) + 17,20 lyase = ______
DeHydroEpiAndrosterone (DHEA) (C19): Ketone formed instead of side chain
How is T3 metabolized?
Deaminated and decarboxylated to form TRIAC
What is Gonadotropin-releasing hormone's (GnRH-1) structure?
Decapeptide (10 AA)
ANG-I
Decapeptide Angiotensin I; Formed by Renin's enzymatic activity on Angiotensinogen
What is a major hormonal change that occurs just prior to birth in many species? In what species is this NOT the case?
Decline in P4 just prior to birth; Not so for humans, guinea pigs
What is a normal result for a Low dose DEX Test?
Decrease in cortisol; Indicates proper functioning of negative feedback
5α-reductase deficiency
Deficiency in 5α-reductase enzyme causing lack in DHT, which is responsible for secondary sex characteristics
What is another side effect present in about half of patients with Acromegaly? Why?
Deficient in other tropic hormones (usually GTHs); Due to excess growth of GH tumor that suppresses other tropic cells in pituitary
What happens to the Fetal Zone of the adrenal gland after birth?
Degenerates rapidly after birth; Nearly gone by 1 year
At autopsy, what is found in many patients with Diabetes insipidus?
Degeneration of SON and PVN (location of AVP production)
What is the enzyme that converts T4 (Thyroxine) to T3 (Triiodothyronine)?
Deiodinase
How is Reverse T3 (rT3) formed?
Deiodination by D1 or D3 deiodinase
What adverse effects can persistently high levels of glucocorticoids have on reproduction?
Delay or prevent reproduction
What surrounds each follicle in the mammalian thyroid gland?
Dense network of capillaries
Progesterone (C21) + 21α-hydroxylase = ______
Deoxycorticosterone (C21): Hydroxyl at C21 on side chain
Both the ______ and the ______ variables should be well-defined in a good experimental design.
Dependent; Independent
How do Ligand Receptor Assays work?
Determine how much non-specific binding there is by adding an excess of "cold" hormone, which will displace all the labeled hormone from the receptor, leaving only the labeled hormone bound to non-specific proteins
What is the result of the removal of the pituitary adenoma as treatment for Cushing's Disease?
Development of hypoadrenocorticism; Glucocorticoid replacement therapy required
Thyroid hormones are important ______ and ______ bioregulators.
Developmental; Metabolic
How can Cushing's Disease be detected?
Dexamethasone or "DEX" Test
What is one endocrine disorder of the Hypothalamus mentioned?
Diabetes insipidus
______ is a period of sexual inactivity that will last until the next breeding season.
Diestrus
What is our body's primary source of iodide, used in thyroid hormone synthesis?
Diet
Why is FSH's half-life so much longer than that of TSH or LH? (All Type 1 hormones)
Differences in carbohydrate components (longer with more carbohydrates)
The α-, β-subunits of Type 1 hormones (Glycoproteins) are encoded by ______ ______.
Different genes
Cross Talk
Different signaling cascades can "talk" with each other leading to complicated network of molecular regulation of cell response
What happens to the androgens (lipophilic) after they are produced by the Leydig cells?
Diffuse across basal lamina to Sertoli cells
What is the end substrate in the ∆4-pathway?
Dihydrotestosterone (C19)
Testosterone (C19) + 5α reductase = ______ Testosterone (C19) + Aromatase = ______
Dihydrotestosterone (C19): ∆4-pathway; Double bond reduced to single at C5 in Ring A Estradiol (C18): A ring becomes aromatic
Why is the conversion of testosterone to dihydrotestosterone (DHT) in the cytosol of target cells important?
Dihydrotestosterone (DHT) is required for some steps in reproductive development (e.g., penis, scrotum, prostate)
Some actions of androgens occur via the conversion of testosterone to ______. Where does this occur?
Dihydrotestosterone (DHT); Cytosol of target cells
Cytokine Receptors must ______ for cytokine (hormone) to bind.
Dimerize
Steroid Nuclear receptors form ______ with other receptors before being able to bind to DNA.
Dimers (Heterodimer or Homodimer)
Sertoli cells are in ______ contact with germ cells.
Direct
What was the summary of Dr. French's work concerning glucocorticoids?
Direct competition for resources leads to trade-offs, which are dependent on energy and external stressors
Pituitary (Location)
Directly beneath third ventricle; Connected to hypothalamus via stalk-like structure; Sits in hypophyseal fossa
What is the action of Melanotropin (α-MSH) in mammals?
Directs melanocytes in skin to produce melanin, which is then stored in keratinocytes
What denotes a measure of a receptor's affinity for a ligand?
Dissociation constant (Kd)
What type of rhythm does Melatonin in the blood have?
Distinct diurnal rhythm (day-night cycle)
What are some examples of animals that are monoestrus?
Dog, wolf, fox, bear
What animals have a Zonary placenta?
Dogs, cats
How common is Cryptorchidism in dogs? Cats? Horses?
Dogs: Common (10%) Cats: Rare (1%) Horses: Common
Hyperthyroidism is rare in ______ and ______.
Dogs; Horses
How is the Catecholamine Dopamine formed?
Dopa decarboxylase removes the carboxyl group from the side chain
What appears to be the physiological Melanotropin Release-Inhibiting Hormone (MRIH) in many species?
Dopamine
What is the potent inhibitory hormone or "brake" that prevents (controls) PRL release?
Dopamine (DA), also called Prolactin-Release Inhibiting Hormone (PRIH)
How is the Catecholamine Norepinephrine formed?
Dopamine enters granulated storage vesicles and is converted to Norepinephrine by dopamine β-hydroxylase
What is the neurotransmitter (CNS) control of Thyrotropin-Releasing Hormone (TRH)?
Dopamine inhibits Norepinephrine stimulates
What is the function of Inhibin?
Down regulates FSH synthesis by pituitary, inhibiting FSH secretion
Positive Feedback Loop
Drives the system away from preprogrammed condition toward a different level of activity; Used when rapid response of the system is needed
Alveoli are continuous with ______, which allow for ______.
Ducts; Milk storage
Why is the surge in FSH smaller than that of LH at ovulation?
Due to Inhibin
Why is low thyroid hormone production (Hypothyroidism) expecially serious in children?
Due to importance of thyroid hormones in growth and development
Why is GH's neurotransmitter so complex?
Due to two regulating peptides, SST and GHRH
When are circulating levels of GH at their maximum?
During maximal growth phase; 2-17 yrs in humans
When do episodic bursts of GH occur?
During periods of LOW SST and HIGH GHRH
When are females receptive to breeding?
During periods of elevated estrogen (E2) known as Estrus
When is the hormone Arginine Vasopressin (AVP) used in the regulation of Adrenocorticotropin (ACTH)?
During periods of stress
Precocious Puberty
Early puberty; Development of any one feature of puberty at 3 standard deviations below mean age at which normally observed
Free thyroid hormones enter cells ______.
Easily
In a High Dose DEX Test, what does High Cortisol and Normal ACTH indicate?
Ectopic ACTH syndrome; ACTH is being produced elsewhere in the body
What is the primary action of Glucocorticoids (Cortisol)?
Effects on energy metabolism
What is the major effect of the adrenal catecholamines Epinephrine and Norepinephrine? (Adrenal Medulla)
Effects on metabolism in response to stress
What is one major difference in oogenesis in non-mammalian vertebrates compared to mammalian vertebrates?
Egg development includes the process of vitellogenesis, which is the production of yolk proteins to support development of the embryo
Prototheria or Monotremes
Egg laying mammals
How can glucocorticoids affect immune system function?
Elevated glucocorticoids inhibit inflammatory response and antibody production
What are Autocrines (Cytocrines) target?
Emitting cell
The placenta is a ______ tissue
Endocrine
Color change in amphibians is under ______ regulation.
Endocrine (Morphological)
Female hormonal contraception is intentional ______ ______.
Endocrine disruption
______ glands release ______ into circulation to convey information to ______ that contain hormone ______.
Endocrine; Hormones; Target cells; Receptors
T4 is ______ from the colloid space through the follicle into the _______.
Endocytosed; Blood
In Estrus, what happens to the uterine endometrium if conception does not occur?
Endometrium is resorbed
Animals with a menstrual cycle (primates) shed their _______ through a process called _______.
Endometrium; Menstruation
Renin
Enzyme released due to either 1) low blood pressure within renal arterioles or 2) low sodium; Secreted by JGA
Angiotensin Converting Enzyme (ACE)
Enzyme that converts ANG-I to ANG-II in lungs
COMT: Catechol-O-methyl transferase
Enzyme that degrades Catecholamines in neuroglial cells and most peripheral cells (Makes water-soluble for excretion)
What is another name for the Pineal Gland?
Epiphysis
Adenohypophysis (Anterior lobe)
Epithelial glandular structure; Primary site of hormone production; 3 regions distinguished by cytological features and anatomical arrangement
Adrenal Medulla structure
Essentially a modified sympathetic ganglion due to large clusters of 20-30 thousand nerve cell bodies that deliver information about impending stress
Ovulation occurs as a result of the progressive increase in circulating ________. How?
Estradiol (E2); E2 exerts positive feedback at the surge center of the hypothalamus to induce a massive increase in LH secretion
How do pigs maintain the CL during pregnancy by blocking luteolytic hormone (PGF2α)? What does this process require?
Estrogen redirects PGF2α to endometrial lumen (exocrine) rather than diffusing into the blood (endocrine); Requires at least two embryos, one in each uterine horn
Concerning steroid production during the ovarian cycle, what do growing follicles secrete under stimulation by LH and FSH and other paracrine factors?
Estrogens
What are the dominant steroids during the Follicular phase?
Estrogens (from the dominant follicle)
Besides androgens, ______ have also been found to be important in spermatogenesis. How was this discovered?`
Estrogens; Estrogen receptors are present on germ cells that also possess aromatase activity (Aromatase knock-out mice exhibit disrupted spermatogenesis, supports role for estrogen)
When and where was the first clinical description of cretinism syndrome, a severe thyroid deficiency in fetal and early development, made?
Europe, 1526
Where and when was Myxedema, which is linked to hypothyroid function discovered? What are its symptoms?
Europe, 1880s; Abnormal accumulation of water and protein in body, altered facial features - expressionless
Hyperaldosteronism (w/result)
Excess production of Aldosterone; Results in high Na+ and low blood K+ leading to muscle weakness
What is the result of the pituitary adenoma (tumor) that causes Cushing's Disease?
Excess secretion of ACTH; Not sensitive to feedback by glucocorticoids, leading to enlarged adrenal gland (zona fasciculata)
What are the consequences to thyroid gland structure and size due to Graves' disease?
Excess stimulation by LATS causes overgrowth of follicular cells (hypertrophy) and increase in number (hyperplasia)
What is the impact of Congenital Adrenal Hyperplasia (CAH) on the adrenal glands?
Excessive ACTH secretion leads to adrenal gland hyperplasia and hypertrophy
What are the symptoms of Diabetes insipidus?
Excessive thirst and urination; Similar to diabetes mellitus, but no glucose in urine or hyperglycemia
Selye's General Adaptation Syndrome: Exhaustion Phase
Exhaustion of lipid reserves (mobilized all possible fat and protein stores)
What are the symptoms in appearance of Hyperthyroidism or Graves' disease?
Exophthalmus or bulging eyes
What are Pharmacological hormone levels?
Experimental manipulations usually utilize much higher (mg/ml) doses
What is iodide uptake controlled by? What is this importer's expression controlled by?
Expression of NIS; Transcriptional control by TSH
Hypothalamo-Hypophysial Portal System
Extensive vascular portal system between Median eminence of the posterior pituitary and Pars distalis of the anterior pituitary
Where are Cytocrines found (compartment)?
Extracellular fluid
Where are Exocrines or Semiochemicals found (compartment)?
Extracellular via ducts to environment
Myxedema
Extreme clinical disorder in which NO thyroid hormones are secreted; Accumulation of high protein fluid causes swelling of skin/subcutaneous tissues
What ultimately happens to spawning salmon concerning their HPA axis?
Extreme stress and extensive activation of HPA axis leads to adrenal exhaustion and eventual death
What is the abbreviation for Cortisol?
F
Inhibin and Activin ONLY affect ______ levels.
FSH
There is no cyclic variation of _____ in human males.
FSH
What stimulates the release of Inhibin in females?
FSH
How is local production of Estradiol (Estrogens) increased in males?
FSH increases aromatase activity in Sertoli cells, thus increasing the conversion of Testosterone to Estrogens
What is the pathway of Inhibin release and action in females?
FSH stimulates secretion of Inhibin by ovary; Inhibin suppresses FSH release
What are the 3 subtypes of Gonadotropes?
FSH, LH, and FSH+LH
What gonadotropin acts on the male's Sertoli cells? What is the result (4)?
FSH; 1) Increased Aromatase 2) Increased Androgen-binding protein (ABP) 3) Increased Inhibin 4) Indirectly initiates spermatogenesis
______ stimulates ______ follicles to enlarge and differentiate into ______ follicles.
FSH; Primordial; Primary
What hormone's release is blocked by Inhibin? Where is Inhibin secreted from in males?
FSH; Secreted by Sertoli cells of testis
Androgen-Binding Protein (ABP)
Facilitates androgen transport to Epididymis; Needed for maintenance of sperm once they leave "nurse" environment
How does ACTH have a permissive effect on the cells of the Zona glomerulosa of the Adrenal Cortex?
Facilitates cells in their synthesis of Aldosterone, but ACTH is not necessary for synthesis
Primary Amenorrhea
Failure of menarche (menstruation) to occur at the normal time
Placebo Control
Fake substance (as in controlled exposure, such as a drug study)
Sham Control
Faked surgical intervention (or injection)
The pathway for Ca²⁺ as a 2nd messenger occurs very ______.
Fast (stored within ER)
How fast is the response to Steroids when they act on the cell surface membrane via G Protein-Coupled Receptors (GPCR)? What are 2 examples of this process?
Fast; Sperm motility, Oocyte activation
What is the default developmental pathway?
Female
What occurs in the Post-luteal or Menstrual phase of the Uterine cycle in polyestrus species?
Female can quickly re-enter proestrus, resuming steroid production to support endometrium
How is female oogenesis different than spermatogenesis concerning germ cells?
Female germ cells have all progressed to primary oocyte phase at birth; No new oocytes appear after birth (In males, spermatogonium are renewed)
Chorionic Somatomammotropin (CS) or Placental lactogen is important in ______ and ______. When does it occur in pregnancy?
Fetal growth; Milk letdown; Last trimester
Chorion
Fetal portion of placenta
What is the ideal temperature for spermatogenesis in male mammals?
Few degrees lower than body temperature
What amino acids are biologically active in single peptide of the Type 3: Small peptide hormone Adrenocorticotropin (ACTH)?
First 23 AA residues
Somatolactin (SL) is ONLY found in ______.
Fish
Steroids do not exist in a ______ plane and may exist as ______.
Flat; Stereoisomers
Follicular phase of estrous cycle
Follicle is dominate structure; Tonic center in hypothalamus releases small quantities of GnRH in pulsatile manner
What is the structural effect on the thyroid gland by canine lymphocytic thyroiditis?
Follicle is surrounded by a densely cellular infiltrate of lymphocytes and plasma cells
What structures are found in the thyroid gland that secrete thyroid hormones?
Follicular cells
Where are Thyroid Hormones synthesized?
Follicular cells of thyroid gland
Follicostellate cells tend to form a ______ structure where they ______ one another.
Follicular; Contact
Thyroid ______ cells line the ______-filled colloid.
Follicular; Fluid
Graves' disease
Form of Hyperthyroidism; Autoimmune disease; Stimulation of TSH receptors by LATS immunoglobulin
Isosexual Precocity
Form of Precocious Puberty; Involves early puberty indicators of genetic sex (Ex. Male, with male indicators)
Heterosexual Precocity
Form of Precocious Puberty; Involves early puberty indicators of non-genetic sex (Ex. Male, with female indicators)
What is the function of the Hypothalamo-Hypophysial Portal System?
Forms neurovascular link between hypothalamus and pituitary; Carries blood and neurohormones to anterior pituitary
When are Gene Reporter Assays frequently used concerning hormones?
Frequently used for receptor transactivation assays (Ex. estrogen receptor) (Tests receptor behavior)
Parr salmon
Freshwater physiology, sedentary, cryptic markings
How much do amino acid, peptide and protein bioregulators vary in length?
From single AA to large protein molecules of more than 200 AAs
What occurs in the Post-luteal or Menstrual phase of the Uterine cycle in monoestrus species (some carnivores)?
Functional layer of endometrium is slowly resorbed
Adenohypophysis: Pars tuberalis (function)
Functions as additional, but limited, source of tropic hormones
What is the function of the Corpus luteum?
Functions as endocrine gland, making large amounts of Progesterone and Estrogens; These steroids exert negative feedback on hypothalamus to decrease GnRH production during Luteal phase to block development of other follicles
What is the function of Chorionic Somatomammotropin (CS) or Placental lactogen produced by the placenta in the last trimester?
Functions like growth hormone (metabolism, fetal development) and Prolactin (stimulates milk synthesis by mammary gland)
Steroids can act at the cell surface by interacting with what receptor type? How does this occur?
G Protein-Coupled Receptors (GPCR); Activates intracellular signaling pathways and kinase cascades
In primates, Lactogenesis is also stimulated by ______, along with the other normal hormones.
GH
What is the action of the Type 2 hormone GH that is not shared by the other two Type 2 hormones, PRL and CS?
GH regulates body growth and metabolism
What is GH's daily secretory rhythm?
GH released at onset of deep sleep; GH is high when sleeping to build tissues
The human placenta also makes pituitary forms of ______ and _______.
GH; PRL
Chorionic Somatomammotropin (CS) is very similar to ______ and ______ in humans and more like ______ in other species.
GH; PRL; PRL
What is the receptor action of all Type 1 hormones, FSH, LH, and TSH?
GPCR stimulates production of cAMP
What is another name for Seven Transmembrane Domain Receptors?
GPCR: G-Protein Couple Receptors
What is the Type 1 hormone FSH's primary action?
Gamete preparation
What is the Type 1 hormone LH's primary action?
Gamete release; Sperm release in males; Ovulation in females
What are the treatments of Polycystic Ovarian Syndrome (PCOS/POD) directed towards?
Geared toward correcting symptoms of primary concern to patient
Polycystic Ovarian Syndrome (PCOS/POD)
General thickening and simultaneous luteinization of several follicles; Results in formation of numerous cysts in ovaries
What are the causes of Polycystic Ovarian Syndrome (PCOS/POD)?
Generally unknown, possibly: 1) Genetic background 2) Linked to other endocrine diseases: Ex. Type II diabetes, obesity, metabolic syndrome
Congenital Adrenal Hyperplasia (CAH)
Genetic defect in one or more steroidogenic enzymes leading to low glucocorticoid synthesis
The genetic males with a 5α-reductase deficiency are often reared as girls, but what event occurs at puberty?
Genetic males experience an apparent shift of sex at puberty; Massive production of testosterone is sufficient to trigger male development
The cyclical nature of female reproductive events is a ______ determined female characteristic.
Genetically
What is an example of indeterminate growth? What is it due to?
Giant sea clams and the phenomenon of "island gigantism" and "marine gigantism;" Related to environmental conditions, abundant food, and few predators, NOT GH dysregulation
Adeno means _______.
Gland; Ex. Adenohypophysis
What is the treatment or therapy for Addison's Disease?
Glucocorticoid replacement
______ (Corticosteroid) secretion is always elevated during the ______ season.
Glucocorticoid; Breeding
What hormone is synthesized in the Zona fasciculata of the Adrenal Cortex?
Glucocorticoids
Zona fasciculata: Hormones produced; Regulation
Glucocorticoids (Cortisol); Regulated by ACTH, Tissue IS responsive to ACTH
What is the main feedback signal in Adrenocorticotropin (ACTH) secretion caused by? What type of feedback is it?
Glucocorticoids (corticosteroids) via CA1 neurons that innervate PVN; Negative feedback back to hypothalamus, especially during periods of stress
What is the main feedback signal in Adrenocorticotropin (ACTH) secretion caused by? What type of feedback is it?
Glucocorticoids (corticosteroids); Negative feedback back to hypothalamus, especially during periods of stress
What is the main feedback signal in Adrenocorticotropin (ACTH) secretion caused by? What type of feedback is it?
Glucocorticoids; Negative feedback to hypothalamus, especially during periods of stress
What are 2 processes used to conjugate another molecule thus inactivating the steroid in Phase 2 Metabolism of Steroid hormones?
Glucuronidation (add sugar), Sulfonation (add sulfur)
What is GABA (Gamma-AminoButyric Acid) synthesized from?
Glutamate (AA) by Glutamatedecarboxylase
Out of the 3 forms of GnRH only ______ is linked to the HPG axis.
GnRH-1 (hypothalamic)
Where is the Propeptide (Prohormone) prepared for packaging and eventual secretion after it has been directed to the RER by its signal peptide?
Golgi apparatus
In some species (golden hamster) short photoperiods cause ______; _____ has a similar effect.
Gonadal collapse; Melatonin
What is the stimulatory hormone that regulates the synthesis and release of FSH and LH?
Gonadotropin-releasing hormone (GnRH)
Where are Androgens produced?
Gonads, Adrenal cortex (DHEA)
Where are Estrogens produced?
Gonads, Placenta
Where are Progestogens produced?
Gonads, Placenta
Where is Activin produced in females?
Gonads, pituitary, placenta
Where is Inhibin produced in females?
Gonads, pituitary, placental corpus luteum
What is the treatment for Cushing's Syndrome caused by glucocorticoid drugs?
Gradual reduction and termination of treatment will alleviate symptoms
What is the result of Thyroiditis?
Gradual reduction in circulating thyroid hormone brings about elevation in TSH, due to loss of negative feedback
Adrenopause
Gradual, yet hardly noticeable, reproductive decline seen in human males
What surround the ovum even after ovulation?
Granulosa cells called Corona radiata
Corona radiata
Granulosa cells that surround and protect oocyte during rupture of follicular wall
What is the Surge center found only in females?
Group of GABA-secreting neurons; Responsible for mid-cycle LH surge in response to elevated estrogen causing ovulation
What hormone makes up half of the total hormone content of the human pituitary?
Growth Hormone (GH)
Somatotrope: Hormone secreted
Growth Hormone (GH) or Somatotropin
What hormone is required to release GH?
Growth Hormone Releasing Hormone (GHRH)
What is an example of an amino acid, peptide and protein bioregulator made up of large protein molecules of more than 200 AAs?
Growth hormone
How is laron-type dwarfism different from the pygmy people of Africa?
Growth is stunted, body proportions abnormal and features distorted
Thyroid hormones regulate ______ and ______ in bony fishes.
Growth; Differentiation
What axis is essentially shut down during pregnancy?
HPG axis
Thyroid hormones also function in the replacement of _____ in adult mammals or ______.
Hair; Molting
Paracrine
Has effect on nearby cells
Autocrine
Has effect on the cell by which it is secreted (Target sites on same cell)
How are the pygmy people of Africa different from those with Laron-type dwarfism?
Have normal proportions, but short stature
Peptide hormones (w/3 examples)
Have numerous functions; Ex. Oxytocin, insulin, endothelin
Where are Atrial Natriuretic Peptide (ANP) and Brain Natriuretic Peptide (BNP) made?
Heart
In what tissues is Type II Deiodinase expressed?
Heart, skeletal muscle, CNS, fat, thyroid, pituitary (peripheral tissues)
What is Carbon Monoxide (CO) bioregulator produced by? Where is it found?
Heme oxygenase; Found in many cell types
Thyroid hormone receptors (TR) form ______ with other nuclear receptors, inducing transcription.
Heterodimers
Ectopic gonadotropin and gonadal steroidal causes of Precocious Puberty often cause ______ precocity.
Heterosexual
What are the consequences of Cryptorchidism?
High temperature experienced by retained testis damages sperm (Normal testis: Sperm development is normal; Usually fertile)
What are the long photoperiods in ruminants associated with?
Higher PRL secretion (higher PRL reduces melatonin)
What type of animals have a menstrual cycle?
Higher primates
What is the daily pattern of glucocorticoid (cortisol) release? (similar pattern for Aldosterone)
Highest from 6-9AM; Minimal during sleep
What is required for organisms that are "regulators", which maintain a physiological state that is substantially different from their own environment? (Ex. warm-blooded animals)
Homeostasis
What does the horizontal line in Selye's General Adaptation Syndrome stress model represent?
Homeostasis or normal level of resistence
Receptors are part of the ______ pathway and convey information delivered by ______.
Homeostasis; Hormones
What must corticosteroid receptors form before binding to specific Hormone Response Elements in the promoter region of target genes?
Homodimers
What must sex steroid receptors form before binding to specific Hormone Response Elements in the promoter region of target genes?
Homodimers
______ of TRs produce little transcriptional response.
Homodimers
Distribution of tropic cells is not ______. There are regions of high density of specific cell types.
Homogenous
A dose response curve that is U- or J-shaped would be an example of ______.
Hormesis
What confers specificity in steroid receptor's binding action?
Hormone Response Elements
Steroid receptor "zinc-finger domains" interact with ______.
Hormone Response Elements (HRE) in promoter region of target gene in DNA
Somatolactin (SL)
Hormone in fish; Produced in Pars intermedia
How are hormone signals from outside of the cell conveyed to the molecular machinery within the cell that must produce the appropriate response?
Hormone passes on the message to intracellular molecule, the second messenger
What is a possible therapy for Menopause's side effects? What is the risk to this therapy?
Hormone replacement therapy using estrogen usually in combination with progestogen; Prolonged treatment may increase risk of some cancers
How can Cryptorchidism be diagnosed in horses with no medical history?
Hormone tests: hCG challenge test- Causes spike in testosterone if testis is present
Besides the normal products of Lactogenesis, milk contains ______.
Hormones (Ex. Tropic hormones, growth factors, steroids, prostaglandins, thyroid hormones, etc.)
Catecholamines
Hormones released by adrenal glands in response to stress (fight or flight)
Allelomones
Hormones released into the environment; Signal to members of different species
Pheromones
Hormones released into the environment; Signal to members of the same species
What animals have a Diffuse placenta?
Horse, swine
Primary Hypothyroidism is not common in _______, and the symptoms are often confused with ______.
Horses; Equine Cushing's Disease
What do Radioimmunoassays (RIA) tell you?
How much hormone is in the sample (concentration)
What is an example of a Steroid-secreting Cell?
Human granulosa cell
What animals have a Discoidal placenta?
Humans, rodents
Aromatase
Hydrogenation of ketone at C3 and conversion of ring A to aromatic
T3 and T4 are ______, and thus are not very ______ in blood.
Hydrophobic; Soluble
Cushing's Syndrome
Hyperactivity of adrenal gland (umbrella syndrome)
What symptom occurs in most cases of Addison's Disease? Why?
Hyperpigmentation; Excess ACTH can bind to α-MSH receptors
What is the most common endocrine disorder observed in cats (middle to older age)?
Hyperthyroidism
What are most cases of Thyrotoxicosis due to?
Hyperthyroidism, an inappropriate excess secretion of thyroid hormone
Patients with Addison's Disease are typically ______. Why?
Hypoglycemic; Due to low cortisol and low gluconeogenesis
Neurovascular Hypothesis
Hypothalamic neurohormones released into portal circulation are responsible for controlling tropic hormone release from pituitary
What is the communication between the central nervous system and reproductive system achieved through?
Hypothalamic-pituitary-gonadal axis (HPG)
Type 1 Endocrine System
Hypothalamic-pituitary-target gland system
What major system do Teleost fish lack that leads to their pituitary direct innervation?
Hypothalamo-hypophyseal portal system
The ______ exerts direct control over pituitary function.
Hypothalamus
What controls the cyclical nature of female reproductive events?
Hypothalamus
Where are Neurohormones made?
Hypothalamus
Where are nonapeptides synthesized?
Hypothalamus
Where is Growth Hormone Releasing Hormone (GHRH) produced?
Hypothalamus
Where is PRL-inhibiting Dopamine (DA) or Prolactin-Release Inhibiting Hormone (PRIH) produced?
Hypothalamus
Where is Somatostatin (SST) or Growth hormone-release inhibiting hormone produced?
Hypothalamus
Where is Thyrotropin-Releasing Hormone (TRH) produced?
Hypothalamus
Where is Vasoactive Intestinal Peptide or VIP secreted from?
Hypothalamus
What is the path of the 2 major classes of hormones released by the Hypothalamus (RH, RIH)?
Hypothalamus secretes RHs, RIHs, stores them in median eminence, and releases them to the pars distalis and pars intermedia where they regulate release of tropic hormones
What axis' activity suppresses immune system function?
Hypothalamus-Pituitary-Adrenal Axis (HPA)
The tropic hormones affect some non-endocrine targets, but most have endocrine targets that in turn release hormones that have specific effects on target cells and feedback at the ______ or ______.
Hypothalamus; Adenohypophysis (pars distalis)
Where is the stimulatory Corticotropin-Releasing Hormone (CRH) produced?
Hypothalamus; Highest amounts in neurons of the periventricular (PVN)
Where is the stimulatory Corticotropin-Releasing Hormone (CRH) produced?
Hypothalamus; Highest amounts in neurons of the periventricular (PVN) and supraoptic nuclei
The axons of neurosecretory neurons extend from what origin structure to what 2 distal structures?
Hypothalamus; Median eminence; Pars nervosa
Where is GnRH-1 produced?
Hypothalamus; Neurons in POA and medial basal hypothalamus
Where is Thyrotropin-Releasing Hormone (TRH) produced?
Hypothalamus; Neurons of PVN
Where is the Prolactin-Releasing Hormone (PRH) produced?
Hypothalamus; Neuropeptide VIP
Where is Oxytocin synthesized? Where is it stored?
Hypothalamus; Pars nervosa of pituitary
All of the gene-linked autoimmune disorders leading to Thyroiditis are associated with ______.
Hypothyroidism
What is the most common endocrine disorder in dogs?
Hypothyroidism
What Insulin-like growth factor (IGF) does GH induce the expression of in both children and adults?
IGF-I
What is the main feedback signal in GH secretion caused by? What kind of feedback is it?
IGF-I; Negative feedback at hypothalamus stimulates SST release, which reduces sensitivity of somatotropes to GHRH
What Insulin-like growth factor (IGF) does GH induce the expression of during fetal growth?
IGF-II
Uterine cycle: Post-luteal or Menstrual phase
If pregnancy does not occur, the Corpus luteum will rapidly regress resulting in a decrease in E2 and P4 production; Steroid withdrawal causes rapid regression of endometrium
Because of broad actions of hormonal chemical regulators, Homeostasis can be profoundly affected by endocrine ______.
Imbalances
Selye's General Adaptation Syndrome: Alarm Phase ("Fight or Flight")
Immediate response to stress; Epinephrine, Norepinephrine are dominant hormones; General sympathetic activation
The well-known ______ effects of glucocorticoids have been exploited by pharmacological glucocorticoids.
Immunosuppressive
Where are TRα-1 and TRβ-1 thyroid hormone receptors (TR) found?
In all tissues
What hormone produced by the gonads produces the primary feedback on the hypothalamus in males? In females?
In males: Testosterone In females: Estrogen
What is the process of Thyroid hormone synthesis from T4 (Thyroxine) to T3 (Triiodothyronine)?
In peripheral tissues, final deiodination by deiodinase removes 3' iodine from the outer ring, forming T3 (Triiodothyronine)
Where is α-MSH made?
In skin after exposure to UV light
What is the action of Type III Deiodinase?
Inactivation of T3
Catecholamines are quickly metabolized into ______ compounds.
Inactive
Propeptide = ______ + ______
Inactive fragment + Hormone
Ovarian cortex
Includes ovarian follicles and stroma surrounding them
What hormone has been linked to the reduction in Melatonin release?
Increase in PRL at onset of day
Why would patients with Graves' disease have a high basal metabolic rate?
Increased thyroid hormones leads to increased cellular metabolism and thermogenesis
The actions of androgens at the gonad are likely ______. Why?
Indirect; Testosterone receptors are absent on germ cells
What general structure do Indoleamines have?
Indoleamine base structure
Indoleamine: Serotonin (KNOW STRUCTURE)
Indoleamine with long amine chain
What hormones are produced and released into the blood by the Pineal Gland?
Indoleamines: Serotonin, Melatonin
What function do androgens have on the epididymis?
Induce epididymis to produce factors that facilitate maturation and maintenance of sperm
What is one pharmacological use of Oxytocin (OXY)?
Induce labor
What is the portion of the oviduct that "catches" the ovulated oocyte?
Infundibulum
Melanotropin (α-MSH) regulation is under _____ control.
Inhibitory
Prolactin's (PRL) main control system is ______.
Inhibitory; Pituitary releases PRL only when inhibition, Dopamine, is removed
Melatonin _____ gonadotropin release.
Inhibits
Melatonin ______ thyroid function in some mammals. How?
Inhibits; Inhibits thyrotropin-releasing hormone (TRH)
What does the Inner Cell Mass of the Blastocyst become? Trophoblast cells?
Inner Cell Mass: Embryo Trophoblast cells: Placenta
Adrenal Medulla
Inner portion of adrenal gland; Adrenal catecholamine synthesis
Endometrium
Innermost epithelium layer; Has both Basal layer and Functional layer
Ovarian medulla
Innermost layer; Usually absent of ovarian follicles
What hormone does GH cooperate with to channel the utilization of amino acids, fatty acids, and carbohydrates?
Insulin
What is an example of post-translation (Prepropeptide, Propeptide, Hormone) of peptides?
Insulin
What intermediate do many actions of GH occur indirectly through?
Insulin-like growth factors (IGF) (peptide growth factor with insulin-like activity)
Relaxin
Insulin-like peptide made during pregnancy; Facilitates relaxation and softening of pelvic ligaments, allowing pelvis to stretch and expand during birth
What does postnatal development of the mammary glands involve?
Integrated regulation by hormones from the: Pituitary: GH Ovary: Estrogens Adrenal cortex: Corticosterone
How do ruminants maintain the CL during pregnancy by blocking luteolytic hormone (PGF2α)?
Interferon tau (IFNτ) acts on endometrium to prevent PGF2α release
What is 1 example of Autocrines?
Interleukins
What is another name for Leydig cells?
Interstitial cells
Some endocrine cells are isolated and do not form discrete structures, such as in the ______.
Intestine
Where are Intracrines found (compartment)?
Intracellular
Intracrines
Intracellular bioregulators that have molecular targets within the emitting cell
What is the site of enzyme activity or transduction to cell signaling cascade in Cell-surface or Transmembrane Receptors?
Intracellular domain
The symptoms of Hyperthyroidism and Hypothyroidism seem to be ______ of each other.
Inverses
What are the Catecholamines Epinephrine and Norepinephrine released by the Adrenal Medulla involved in?
Involved in emergency reaction i.e. "fight or flight" response
What is the treatment for Hypoaldosteronism?
Involves increased salt intake (due to low Na+) and Aldosterone replacement
First phase of lactation: Lactogenesis or milk secretion
Involves synthesis of milk fat, milk protein, and milk sugar
What molecule is critical for thyroid hormone synthesis?
Iodide
What are the iodide concentrations in the thyroid gland compared to those found in the blood?
Iodide concentrations in thyroid gland are often 20x to 40x greater than blood
_____ is taken into the thyroid follicular cells through the blood.
Iodine
What are 90% of the cases of Goiters caused by?
Iodine deficiency (Hypothyroidism most common cause)
What has eliminated the health problems associated with thyroid hormone deficiencies in developed countries?
Iodized salt
In mammals, there (Is/Is not) a direct neural connection between the Hypothalamus and the pituitary (unlike in teleost fish).
Is NOT
The human variant of TSH, Long-Acting Thyroid Stimulator (LATS), (Is/Is not) made by the thyroid gland.
Is NOT
What endocrine tissue is organized into scattered clumps or islets of single or mixed cell types?
Islets of Langerhans (Pancreas)
When a message experiences Agonistic (cooperative) Cross Talk, what happens to the message?
It is reinforced
When are peak levels of Relaxin seen?
Just prior to birth; Disappears afterwards
What are the 2 triggers for use of the Renin-Angiotensin System?
Juxtaglomerular apparatus (JGA) have receptors that detect when stretched due to 1) low blood pressure/volume and/or when there is 2) low [Na+]
Why is Arginine Vasopressin (AVP) used in the regulation of Adrenocorticotropin (ACTH) during periods of stress?
Keeps corticotropes responsive to CRH by blocking negative feedback of glucocorticoids during high stress
Why is Arginine Vasopressin (AVP) used in the regulation of Adrenocorticotropin (ACTH) during periods of stress?
Keeps corticotropes responsive to Corticotropin-Releasing Hormone (CRH) by blocking negative feedback of circulating glucocorticoids during high stress
Glomerulus
Kidney filtration site
Why are thyroid hormones produced in excess when LATS binds TSH receptors?
LATS has a longer half-life of 7.5 hours compared to 15 minutes for TSH, therefore thyroid hormones are produced in excess
What is the antibody that stimulates TSH receptors in Graves' disease?
LATS: Long-Acting Thyroid Stimulator (a.k.a. thyroid-stimulating immunoglobulin)
What is Spermiation stimulated by?
LH
______ release triggers synthesis of ______ by Leydig cells.
LH; Androgens
What gonadotropin acts on the male's Leydig cells? What is the result?
LH; Increase in androgens that travel to Sertoli cells
What causes the dwarfism in the pygmy people of Africa?
Lack GH binding proteins for transport, therefore unable to maintain normal circulating levels of GH
How does Congenital Adrenal Hyperplasia (CAH) deviate from the normal HPA axis?
Lack of cortisol production (caused by mutation) and its negative feedback allows for excess production of ACTH and excessive growth of adrenal gland
Dwarfism
Lack of sufficient GH production in early life resulting in reduced growth
The Type 2 hormone Prolactin (PRL) is best known for what action?
Lactogenic effect on mammary gland in female mammals
What is the treatment for Cryptorchidism in horses?
Laproscopy to remove undescended testis
Mature or Graafian follicle
Large fluid-filled antrum; Granulosa cell layer is thinner; Has Corona radiata and Cumulus oophorus Granulosa cells
Type 2: Long Chain Polypeptides (GH, PRL, CS)
Large, single polypetide hormones of similar structure and size
The Vomeronasal organ is ______ in males than females.
Larger
The medial preoptic area is ______ in males in some mammals.
Larger
On what size hormones do Receptor Tyrosine Kinases (RTKs) work with?
Larger proteins
Adrenal Cortex: Zona fasciculata
Largest zone; Histologically distinct; Cord structures; Polyhedral cells; Surrounded by blood sinusoids i.e. direct contact of cells with blood
Somatotrope: Distribution
Lateral margins
Myometrium
Layer of smooth muscle
Amino acid, peptide and protein bioregulators vary in ______.
Length
What is the therapy for Hypothyroidism?
Levothyroxine (T4 supplement)
In the 2-cell model of steroidogenesis comparison of analogous male and female cells; Leydig = ______, Sertoli = ______
Leydig cells = Thecal cells Sertoli cells = Granulosa cells
What is found within the interstitial space between Seminiferous Tubules?
Leydig cells, blood supply
Nuclear receptors can be activated by signaling pathways or ligand binding. Which is more common?
Ligand binding
Though the physiological role for pulsatile testosterone release is not clear, what is thought to be its importance?
Likely important in proper maintenance of feedback mechanisms on FSH release
What is the result of mRNA translation?
Linear sequence of amino acids (primary structure)
What is the Adenohypophysis' Pars tuberalis a link between?
Link between pineal gland and prolactin-secreting cells of Pars distalis
What type of cells are found in the adrenal gland's Adrenal cortex?
Lipid-containing, steroidogenic adrenocortical cells
Metatheria or marsupials
Live bearing; Continued development in external pouch
Eutheria or placentals
Live bearing; Placenta supports complete fetal development
Where is most of the body's T3 produced?
Liver
Where is the majority of circulating T3 formed in mammals? Where is the rest made?
Liver by Type I deiodination of T4; 15-25% in thyroid, rest in peripheral tissue cells
What organs serve as major sites for the metabolism of bioregulators?
Liver, Kidney
Where does the metabolism of the Indoleamine Melatonin occur? By what enzymes?
Liver, brain; P450 enzymes
T3 is made primarily in the ______ by type ___ ______.
Liver; I; Deiodinase
Where does Cholesterol production primarily occur? How is it transported from its production site?
Liver; Released into blood as protein-coated lipid droplets
Where are Insulin-like growth factors (IGF) synthesized?
Liver; Therefore, liver can be considered target endocrine gland for GH
What is one consequence of the direct innervation found in Teleost fish?
Localization of cell types in regions of pituitary; Unlike mammals, specific cell types for secreting FSH and LH
Hypothalamus (Location)
Located below thalamus and above brain stem; Anterior to pituitary
Where is the thyroid gland located?
Located in the neck region of most mammals, with two lobes on either side of the trachea
Many receptors work by the "______" mechanism.
Lock-and-key
Indoleamine: Melatonin (KNOW STRUCTURE)
Long amide chain (NH=O) with methyl group on ring hydroxyl
Catecholamine: Dopamine (KNOW STRUCTURE)
Long amine chain; Released by Hypothalamus
What is the structure of the Insulin prohormone?
Long polypeptide folded through formation of disulfide bonds between cysteine residues; Contains C-peptide (inactive fragment)
What is the human variant of TSH? What is it associated with?
Long-Acting Thyroid Stimulator (LATS); Aberrant immunoglobulin; Associated with Grave's disease (hyperactive thyroid)
What is the effect of Secondary Hypothyroidism (at hypothalamus or pituitary) on the HPT axis?
Loss of function at pituitary, resulting in low TSH, and thyroid gland, resulting in low thyroid hormones
How does Addison's Disease deviate from the normal HPA axis?
Loss of function of adrenal glands (cause) results in low cortisol, loss of negative feedback, and over production of ACTH (consequence)
How does Cushing's Disease deviate from the normal HPA axis?
Loss of negative feedback by circulating cortisol allows for inappropriate release of ACTH, causing enlarged adrenal gland
Oxytocin (OXY) is the "______" hormone.
Love
Addison's Disease
Low or absent circulating cortisol; Leads to hypersecretion of ACTH
Hypoaldosteronism
Low production of Aldosterone; Results in low na+ and high blood K+
What is the effect of Primary Hypothyroidism (at thyroid) on the HPT axis?
Low production of thyroid hormones, loss of negative feedback at pituitary; Elevated TSH production
How do thyroid hormones affect reproduction?
Low thyroid hormone concentrations delay sexual maturation; Linked to interaction with GTH (gonadotropins)
Seasonal hair loss (molting) in harbor seals is correlated with ______ _____ function and ______ ______ levels. When does hair growth resume?
Low thyroid; High cortisol; Hair growth resumes with increased circulating T4 and return of cortisol to normal levels
What are the levels of FSH and LH during the Follicular phase of the estrous cycle?
Low, but consistent circulating levels maintained
Light present = _____ NE = _____ Melatonin
Low; Low
______ iodide and ______ thyroid hormone is still a significant health problem in underdeveloped nations.
Low; Low
Why are FSH concentrations lower, yet longer, than those of LH due to GnRH?
Lower due to negative feedback by Inhibin; Longer pulse due to longer half-life
Optimal Dose
Lowest dose (or exposure) that produces maximal response; May differ between species
What degrade the Corpus luteum?
Luteolytic factors such as PGF2α produced by the uterine endometrium or estrogen in primates produced by the Corpus luteum itself
What enzyme degrades the Indoleamine Serotonin?
MAO
What are some lifestyle adjustments to help horses with Cushing's Disease cope?
Mainly avoid stressing the horse; 1) Keep water/feed conveniently located and in same place 2) Clip horse in warm weather; Use blankets when cold 3) Maintain good grooming routine 4) Check teeth regularly (Vet twice a year) 5) Avoid turning horse out with aggressive horses 6) Deworm regularly (immune system) 7) Provide appropriate diet: Eliminate simple carbohydrates
What may signal precocial endocrine activity that is pathological in nature?
Major deviations in a number of puberty indicators
Adenohypophysis: Pars distalis
Major portion of anterior pituitary; Contains 5 cell types secreting 6 tropic hormones
What hormone is produced by the Fetal Zone of the adrenal gland?
Major source of adrenal androgen DHEA
Neurohypophysis: Pars nervosa
Majority of lobe; Posterior position of Neurohypophysis; Separate, abundant blood supply
What is the goal of both Phase 1 and Phase 2 metabolisms of Steroid hormones?
Make steroids more water-soluble for excretion either by removal/reduction (Phase 1) or glucuronidation/sulfonation (Phase 2)
Testicular Feminization syndrome is an example of _____ ______.
Male psuedohermaphroditism
Is Sexual Precocity (accelerated sexual maturation) more common in males or females?
Males
Where is the second form of GnRH produced? What was its original name?
Mammalian midbrain; "Chicken II"
All mammals have ______, but only ______ mammals have a fully-functional ______ to support complete fetal development in utero.
Mammary glands; Eutherian; Placenta
What are some examples of animals that are seasonally polyestrus long day breeders?
Mare
What are the consequences of Hypothyroidism in infants and children?
Marked slowing of growth and development
What may be the cause of Cryptorchidism in dogs?
May be a genetically linked trait
What may occur with animals that have reduced activity of the adrenal cortex?
May have delayed reproduction
What is one possible role of Inhibin, besides FSH inhibition, in males?
May locally regulate spermatogenesis
Follicostellate Cell: Function
May serve supporting/nutritional function for surrounding "tropes"; Produce some paracrine growth factors and interleukin-6
What is the structure that separates the Hypothalamus and Pituitary?
Median Eminence (lots of nerves)
The superior hypophysial artery supplies blood to the capillaries in the ______. The (SAME) is connected by hypothalamic portal blood vessels passing through the ______ to the ______ where releasing hormones from the hypothalamus stimulate tropic hormone release.
Median eminence; Pars tuberalis; Pars distalis
Without testosterone, there is no _______ in spermatogenesis.
Meiosis
What are most heritable disorders of the reproductive system a result of?
Meiotic nondisjunction (during creation of sperm or oocyte)
Spermatogenesis
Meiotic process to generate male gametes
What is the only tropic hormone NOT produced in the Pars distalis?
Melanotropin (α-MSH)
_______ is responsible for coat color change in some furred animals.
Melanotropin (α-MSH)
In photoperiodic animals, what has melatonin been found to do to cause their breeding pattern?
Melatonin acts on pituitary to lower circulating LH concentration
Pineal tumors are not common, but occur mostly in ______.
Men
In nature, few animals survive beyond reproductive age due to predation, disease. or other environmental phenomenon. This is not so in modern humans, who live well beyond reproductive viable age. What phenomenon is the result?
Menopause
Reduced thyroid hormones affect ______ capacity.
Mental
What is the source of most circulating T3 in many species?
Metabolism of T4 by deiodination in the liver
What is the special function of thyroid hormones in bony fishes, especially flounder and flatfish?
Metamorphosis: Migration of the eye and associated neural structures from one side of the head to the other
When is Cushing's Disease most often diagnosed in horses?
Mid-age horses (20 years on average)
In what types of dogs does Hypothyroidism commonly develop?
Middle-aged dogs, larger breeds
Migratory birds are quite sensitive to stress stimuli just prior to ______ and ______.
Migration; Breeding: Stress is important for reproductive performance
Threshold Dose
Minimum dose (or exposure) to produce a detectable response
Stereoisomers
Molecular structure is the same, but 3D spatial arrangement differs
Seasonal hair loss = ______
Molting
What do thyroid hormones stimulate in many amphibians (not frogs), reptiles, and birds?
Molting: Shedding of skin
The Type 2 hormones GH and PRL are found in the blood in what forms?
Monomers, dimers or polymers
In what sex is Graves' disease more common?
More common in females than males (8 to 1)
Thyroid hormones affect _______ cells of the body.
Most
Adenohypophysis: Pars distalis (location)
Most anterior of anterior pituitary
Eicosanoid Prostaglandins (PGs) are present in what tissues?
Most tissues of both sexes
What cell type is the most common or abundant in the Pars distalis? Least?
Most: Somatotrope Least: Thyrotrope
Neurohypophysis (Posterior lobe)
Mostly a collection of axonal projections from the hypothalamus with capillaries forming a portal system; 2 regions
Where does the conversion of androgens to estrogens occur in males?
Mostly in Sertoli cells, but to a lesser extent the Leydig cells
What is important to note concerning the HPA axis and stress response differences between captive birds and free-ranging birds?
Mounting an appropriate stress response is key for survival, but prolonged elevated stress can be detrimental
Polyestrous
Multiple estrous periods within a year; Ex. Cats, cows, pigs
What is a condition resulting from extreme cases of Hypothyroidism?
Myxedema
What is the rate limiting step in Melatonin (Indoleamine) synthesis?
NAT (N-acetyltransferase)
A ______ feedback loop drives a physiological system to a preprogrammed set point.
Negative
Androgens and Progestogens have a ______ feedback to the hypothalamus.
Negative
Generally, sex steroids have ______ feedback
Negative
Melatonin has, in general, a _____ impact on tropic hormone release.
Negative
Normal homeostasis is maintained via positive or negative feedback at the hypothalamus?
Negative
Thyroid hormone homeostasis operates via a ______ feedback loop.
Negative
What type of feedback do sex steroids generally have?
Negative
Low levels of estrogen (E2) have a ______ feedback on the hypothalamus, while high levels of estrogen (E2) have a ______ on the hypothalamus.
Negative (-); Positive (+)
What is the most common type of feedback in physiological systems?
Negative feedback loop
T3 exerts a ______ feedback on TRH and TSH release in both the ______ and the ______.
Negative; Hypothalamus; Pituitary
Physiological color change is under direct _____ control, and apparently not controlled by ______.
Nervous system; α-MSH
GnRH neurons form a ______, called ______, that synthesizes GnRH in ______.
Network; GnRH Pulse Generator; Pulses
What is the release of Oxytocin (OXY) induced by?
Neuroendocrine reflex; Suckling sends neural impulses to hypothalamus triggering OXY release from pars nervosa into circulation; OXY then triggers milk release from mammary gland
Since Teleost fish's pituitary is directly innervated rather than connected via portal system, these fish are considered "______" rather than "_____," like other animals mentioned.
Neuroglandular; Neurovascular
What is the 2nd phase of lactation, Milk ejection, controlled by?
Neurohormonal reflex response controlled by Oxytocin; Mechanical stimulation by suckling triggers release of Oxytocin
Neurocrines are released by ______.
Neurons
Where is GnRH-1 produced?
Neurons in POA and medial basal hypothalamus
Neurohormones
Neurons release chemicals that enter circulation and act at distant sites
What is the byproduct of the synthesis of both nonapeptides, Vasopressin and Oxytocin?
Neurophysin I or II
The hypothalamus contains several ______ centers.
Neurosecretory
What must occur before the synthesis of regulatory hormones (RH, RIH) is activated?
Neurosecretory neuron is activated
Acetylcholine bioregulator
Neurotransmitter in peripheral nervous system; Controls production of hormones from pituitary
What is the release of Catecholamine neurotransmitters followed by?
Neurotransmitter's partial re-uptake and recycling and/or degradation by the secreting neuron to free postsynaptic receptors and turn off post-synaptic cell
Type 3 tropic hormone: Endorphins
Neurotransmitters in CNS; Synthesized from POMC precursor
The 3 important Catecholamines are ______, which are synthesized by ______ and cells of the _______.
Neurotransmitters/Neurohormones; Neurons; Adrenal medulla
Indoleamines
Neurotransmitters; Regulate sleep/wake cycle and mood
Can Corticosteroids be converted to Estrogens by any enzyme?
No
How are Leukotrienes structure different from that of the rest of the Eicosanoids?
No 5C ring
What is the feedback mechanism in the regulation of Melanotropin (α-MSH)?
No apparent direct feedback mechanism because melanin stays local
What is the structure of the thyroid found in bony fishes?
No distinct gland, but thyroid follicles are located diffusely in pharyngeal region
How is the CL maintained during pregnancy in horses?
No known mechanism, but require embryo to move around the uterus
Follicostellate Cell: Hormone secreted
No tropic hormones; Do express S-100 protein, characteristic of neuroglial cells
Does Menopause occur in men?
No; Men are generally capable of producing viable sperm most of their lives, but there is a reproductive decline with age called Adrenopause
Iodide accumulation with Graves' disease is not ______, like it is with Plummer's disease or Marine-Lenhart syndrome.
Nodular
What is the source of Cytocrines (Paracrines, Autocrines)?
Non-neuronal cells
What is the source of Exocrines or Semiochemicals?
Non-neuronal cells
What is the source of Hormones?
Non-neuronal cells
What is the source of Intracrines?
Non-neuronal cells
What type of neurohormones, which are made in the Hypothalamus, are stored in the Pars nervosa?
Nonapeptides
______ is stored in neurons for quick release.
Norepinephrine
What is seen at thyroid hormone homeostasis?
Normal T3, T4 concentrations; Normal body temperature
What is the half-life of normal TSH? What is the half-life of the variant of TSH, Long-Acting Thyroid Stimulator (LATS)?
Normal TSH: 15 minutes LATS: 7.5 hours (causing hyperactive thyroid)
What are Physiological hormone levels?
Normal levels; Generally, levels of hormones are very low in the body (pg to μg per ml of blood)
What is not entirely clear about the regulation and release of α-MSH?
Not clear whether release is controlled by neurohormones or by direct innervation from hypothalamic neurons
How common is Addison's Disease in dogs and cats? Horses?
Not very common; Extremely rare
______ are intracellular receptors that, when activated, translocate to the nucleus and bind to DNA.
Nuclear receptors
Thyroid hormones act via binding to ______ receptors to drive ______.
Nuclear; Transcription
What kind of cells are Sertoli cells?
Nurse cells
In species with estrous cycles, when are the females generally sexually active?
ONLY during the estrus phase of their cycle ("in heat")
Once bound to a ligand, the receptor is "______."
Occupied
Secondary Amenorrhea
Occurs after menarche; Patient ceases normal menstrual cycles (> 6 months)
Where does Non-shivering Thermogenesis occur?
Occurs in brown adipose tissue (brown fat)
Where are Norepinephrine and Epinephrine receptors (adrenergic receptors) found?
On presynaptic nerve terminal and postsynaptic cell
Adenohypophysis: Pars intermedia (function)
Only one secreting cell type is present, which produces melanotropin (α-MSH); In mammals, this hormone stimulates skin cells to produce brown pigment
What is claimed to help restore normal rhythms when dealing with Circadian Dysrhythmia (jet lag)?
Oral administration of melatonin
What are Paracrines (Cytocrines) target?
Other nearby cell types
What are Allelomones (Exocrines/Semiochemicals) target?
Other species
What are the symptoms of Circadian Dysrhythmia (jet lag)?
Out of sorts, grogginess, crotchetiness, crankiness
Uterine wall
Outer connective tissue covering
Adrenal Cortex
Outer glandular portion of adrenal gland; Corticosteroid synthesis
What occurs in the Post-luteal or Menstrual phase of the Uterine cycle in higher primates?
Outer portion of the endometrium rapidly regresses, is sloughed off, and shed during menses
What other cycle does the Uterine cycle coordinate with?
Ovarian cycle
Menopause
Ovary becomes refractory to GTH in the mid to late 40s; Reproductive cycles become irregular then cease, resulting in marked decrease in circulating gonadal steroids and adrenal androgens
How is the ovary connected to the rest of the female reproductive system?
Ovary is connected to outer uterine wall via ovarian ligaments, not directly connected to oviduct
What is the effect of Hyperthyroidism on the HPT axis?
Overproduction of thyroid hormones and increased negative feedback at pituitary; Low TSH production
The developing egg will transit through the ______ and then implant in the ______.
Oviduct; Uterus
Activation of the GnRH Surge center is associated with ______.
Ovulation
What is Nitric Oxide (NO) bioregulator produced by?
Oxide synthase (NOS) in the cell
What is the first step in Steroidogenesis for all mammalian tissues capable of producing Steroids?
P450 side chain cleavage of Cholesterol; C27 to C21
How is the Catecholamine Epinephrine formed?
PNMT converts Norepinephrine to Epinephrine
What is the name of the nuclear receptor used by Eicosanoids?
PPAR (Peroxisome Proliferator-Activated Receptor) (has 3 subtypes: α, β, γ)
Eicosanoids bind to the nuclear receptor ______, which forms ______, inducing gene expression.
PPAR; Heterodimers
What is the main feedback signal in PRL secretion caused by?
PRL to Dopamine (PRIH)
Heterodimer (w/example)
Pair of DIFFERENT receptors that dimerize before binding to DNA
Homodimer
Pair of the SAME receptors that dimerize before binding to DNA
Hypothalamic secretory centers are typically ______ structures where the cell bodies (nuclei) of neurohormone-producing neurons are located, hormone secretion though is not necessarily ______ on both sides.
Paired; Balanced
Mammary glands typically occur as ______ structures with ______ locations.
Paired; Varied (thorax, abdomen, inguinal region)
Interleukins function as what type of hormones? Where?
Paracrine and autocrine hormones; In vascular system and lymphatic tissues
The thyroid gland is closely associated with the ______ glands in some mammals.
Parathyroid (visible from rear)
In animals WITH a ______, α-MSH is produced in ______ cells.
Pars intermediate; Melanotrope
Where are nonapeptides stored?
Pars nervosa of most adult mammals
The ______ of the Neurohypophysis stores nonapeptides and has a separate ______.
Pars nervosa; Blood supply
Peritubular Myoid cells
Part of connective tissue layer surrounding seminiferous tubules; Contractile action propels sperm to Epididymis
How is glucocorticoid's daily release pattern changed for nocturnal animals?
Pattern is reversed (high at night; Lowest from 6-9AM)
LH and testosterone exhibit obvious similar daily ______.
Patterns
What are biological rhythms?
Patterns of hormone release
Puberty
Period of development of the HPG axis and functional development of sex accessory structures
Diestrus
Period of sexual inactivity
Estrus
Period of sexual receptivity and fertility
Patterns of hormone release: Phasic
Periodic bursts corresponding to specific timed cycles
What type of cells are found in the basal lamina separating the contents of the seminiferous tubules from the interstitial space?
Peritubular myoid cells
How do thyroid hormones affect growth hormone (GH)?
Permissive effect for growth hormone (GH) by stimulating IGF-1 production
What are thyroid hormones' main biological action?
Permissive effect: Thyroid hormones produce changes in target tissues that allow them to be more responsive to other hormones or stimuli
Glucocorticoids are useful ______ agents.
Pharmacological
Adrenopause
Phase of strong decline of adrenal androgens, DHEA, after ages 40-50
Adrenarche
Phase where adrenal androgens, DHEA, remain high until 20s
What is the Catechol structure common in all Catecholamines?
Phenolic ring with two adjacent (ortho) hydroxyl groups
Cytokine Receptors must wait for protein to bring ______, thus they do not have ______.
Phosphate; Intrinsic kinase activity
The Pineal Gland is a ______ organ. What does this mean?
Photoreceptive; Neurons in optic nerve tell pineal gland about light patterns
There is evidence for precocity in young girls exposed to ______.
Phthalates
What are Indoleamines produced by?
Pineal gland
Circadian Dysrhythmia (jet lag)
Pineal gland disorder; Disruption of normal body rhythms due to air travel; Circadian clock does not match to new photoperiod
Seasonal Affective Disorder (SAD)
Pineal gland disorder; Mood disorder that typically affects patients during winter months and in northern latitudes or regions with little sunshine
Sexual Precocity (accelerated sexual maturation)
Pineal gland disorder; Sexual development is normal, but begins at much earlier age than normal and proceeds more quickly
What is the "master" endocrine gland that contains tropic hormones?
Pituitary Gland
What are the functions of Chorionic Gonadotropin (CG) similar to?
Pituitary LH
What is the 1st phase of lactation, Lactogenesis or milk secretion, primarily controlled by?
Pituitary PRL (or placental CS), growth factors and glucocorticoids
What is an example of a Protein-secreting Cell?
Pituitary cell
Acromegaly
Pituitary disorder; Rare disorder of GH regulation/release; Can lead to Gigantism, abnormal body proportions, shortened life expectancy
A Releasing hormone acts on the ______.
Pituitary gland
A Tropic hormone is produced by the ______.
Pituitary gland
What is the most likely cause of Cushing's Disease in horses?
Pituitary tumor
Canine Cushing's
Pituitary tumor is most common cause; More prevalent in females and small dogs
Ectopic gonadotropin cause of Precocious Puberty
Pituitary tumors occasionally secrete excessive GTHs; Sometimes other tumors secrete chorionic gonadotropin
There are many types of Thyroid Hormone Receptors (TR). Where are TRβ-2 receptors found?
Pituitary, Hypothalamus, other areas in brain
Where are TRβ-2 thyroid hormone receptors (TR) found?
Pituitary, Hypothalamus, other brain areas
How long does the Corpus luteum last in humans, horses, and sheep?
Placenta takes over steroid hormone production after the CL regresses
During pregnancy, what tissue functions as a composite HPG axis? How?
Placenta; 1) Releasing hormones: GnRH; CRH 2) Tropic hormones: CG, ACTH 3) Sex steroids: E2, P4
The Trophoblast cells differentiate into the ______, which continues to secrete ______ throughout pregnancy.
Placenta; Chorionic Gonadotropin (CG)
What is another name for the Type 2 placental hormone Chorionic Somatomammotropin (CS)?
Placental Lactogen
During the last trimester of pregnancy, what occurs in mammary gland development?
Placental estrogens induce hyperplasia and hypertrophy
What is another name for Polycystic Ovarian Syndrome (PCOS)?
Polycystic Ovarian Disease (POD)
What is Secondary Amenorrhea commonly associated with?
Polycystic Ovarian Syndrome (PCOS/POD)
All the tropic hormones secreted by the Adenohypophysis Pars distalis are ______.
Polypeptides or proteins
In experimental design, what does it mean to say "Junk in = Junk out?"
Poor experimental design leads to poor quality data and poorly formed conclusions
After regulatory hormones are activated, they travel through the ______.
Portal system
After tropic hormones are synthesized they are released into the ______ and travel to ______.
Portal system; Peripheral tissues
Adenohypophysis: Pars intermedia (location)
Portion of anterior pituitary that makes contact with the pars nervosa of the posterior pituitary (between lobes)
Asymmetric Carbons
Positions where atoms may bind with different spatial conformations
Estrogens have a ______ feedback to the hypothalamus.
Positive
What is the LH spike or surge that causes ovulation caused by?
Positive (+) feedback by estrogen secreted by the growing follicle
What is the exception to sex steroids primarily producing negative feedback?
Positive feedback by estrogen drives LH surge for ovulation; Mediated by GABA secreting neurons
What do all Type 3 hormones result from?
Post-translational modifications occurring in Pars distalis or Pars intermedia, if present
Pineal tumor cause of Precocious Puberty
Precocious puberty co-occurs with about 33% of pineal tumor cases; Related to disruption of melatonin production
Angiotensinogen
Precursor to ANG-I; Converted by Renin; Secreted by liver
Arachidonic Acid (KNOW STRUCTURE)
Precursor to Eicosanoids
What is the main purpose of T4?
Precursor to T3
Type 3 tropic hormone: Lipotropin (LPH)
Precursor to endorphin synthesis; Pituitary origin
Hypothesis
Predictive statement of what may be the true explanation of observed phenomena; Supported or rejected based upon experimental results
What is a widely used glucocorticoid drug? What is its use?
Prednisone; Anti-inflammatory drug for treatment of rheumatoid arthritis
Cholesterol (C27) + P450 side chain cleavage = ______
Pregnenolone: C21 (1st produced) with Ketone on side chain
Cholesterol (C27) + P450 side chain cleavage = ______
Pregnenolone: C21 with Ketone on side chain
What is the "direct innervation" found in Teleost fish's pituitary?
Preoptic and hypothalamic neurons directly innervate the pituitary, terminating at target cells
Nonapeptides are first synthesized as ______.
Preprohormones
What is a neurotransmitter's regulatory response on the hypothalamus determined by?
Presence of receptors for the neurotransmitters on the neurosecretory neurons
In a High Dose DEX Test, what does High Cortisol and Low ACTH indicate?
Primary adrenal Cushing's syndrome; Cortisol is being released independent of ACTH control
What is the primary action of LH in males?
Primary control of synthesis and release of circulating androgens by Leydig cells
Vitellogenesis
Process by which yolk accumulates in the cytoplasm of an ovarian oocyte; One of the final stages of egg formation, occurring just prior to deposition of chorion (shell)
Luteinization
Process during Luteal phase whereby LH surge induces Granulosa and some Theca cells to differentiate into the Corpus luteum
Thermogenesis
Process of heat production in organisms
Spermiation
Process whereby millions of mature sperm are sloughed off into lumina of Seminiferous Tubules each day
What happens to the products of Lactogenesis?
Products secreted into lumen of Alveolus; Water and other water-soluble factors enter by osmosis
Pregnenolone (C21) + 3β-HSD = ______
Progesterone (C21): Ketone at C3
In humans, there is no drop in ______ to trigger birth.
Progesterone (P4)
What are the dominant steroids during the Luteal phase?
Progesterone (from the Corpus luteum)
In humans, when do maternal Progesterone levels decrease concerning birth?
Progesterone levels do not decrease until after detachment of placenta
In the case of successful fertilization, what hormone must continue to be synthesized? Why?
Progesterone; In order to maintain the functional layer of the endometrium
What are the precursor steroids for all other steroid types?
Progestogens
How does gamete maturation occur in the Seminiferous Tubules?
Progresses from periphery (basal lamina) to interior of seminiferous tubule
Cumulus oophorus
Projection of Granulosa cells into the antrum; Cumulus cells are nurse cells to oocyte
Lactotrope: Hormone secreted
Prolactin (PRL)
What is the hormone that releases PRL?
Prolactin-releasing hormone (PRH), which is neuropeptide VIP
What is the GnRH secretion pattern resulting from activation of the Surge center?
Prolonged release of GnRH at much higher blood concentrations
Transcription Factors form a complex with other regulatory proteins at the ______ region to expose transcription ______ site to ______.
Promoter; Start; RNA Polymerase
What is the precursor to the Type 3: Small Peptides hormones (ACTH, α-MSH, LPH)?
Proopiomelanocortin POMC
In Graves' disease, what are lost due to the strong negative feedback leading to no TSH production?
Proper control mechanisms
What is the basic structure of all Eicosanoids related to?
Prostanoic acid (C20)
______ is NOT the precursor of Eicosanoids, but is the generic structure.
Prostanoic acid (C20)
What is the important function of the Blood/Testis Barrier formed by Sertoli cells?
Protect developing sperm cells from immune system attack
Prepropeptide (Preprohormone)
Protein (hormone) precursor that contains Propeptide and signal molecule
Transcription factor
Protein that binds to DNA and affects transcription of specific genes
Interleukins bioregulator
Proteins secreted by WBCs; Important for immune system function; Promote development and differentiation of T, B, and hematopoietic cells
What are hormone receptors?
Proteins within a cell or on the cell surface that interact in a specific manner with hormones
Adrenal function is correlated with the onset of ______.
Puberty
When does the production of adrenal androgens (DHEA) start in males and females?
Puberty
Beginning at ______ a cohort of follicles selected from ______ follicles begins to grow. The majority of these follicles undergo programmed cell death or ______, while one ______ follicle is selected for ovulation during each ovarian cycle from puberty to ______.
Puberty; Primordial; Atresia; Dominant; Menopause
GnRH release in response to activation of the tonic center is ______.
Pulsatile
In males AND females, GnRH neurons form a network that synthesizes GnRH in _____ called the ______ center.
Pulses; Tonic
Reverse T3 (rT3) is eliminated ______.
Quickly
What is one of the most common techniques for measuring hormones?
Radioimmunoassay (RIA)
What hormone changes occur post-ovulation during the Luteal phase of the estrous cycle?
Rapid decrease in total FSH/LH and GnRH
Physiological control of color change
Rapid response; Under direct neurological control
Chorionic Gonadotropin (CG) can be ______ and easily detected in ______ by a ______ test.
Rapidly; Urine; Antibody
Riedel's thyroiditis
Rare chronic inflammatory disease; Thyroid gland progressively replaced by connective tissue
Diabetes insipidus
Rare hypothalamic condition where patient cannot conserve water (diuresis- excess production of urine)
What may the ratio of estrogen to androgen in circulation alter?
Ratio of FSH and LH released from pituitary through negative feedback
How do teleost fish acquire iodide? What is the result of this?
Readily take up iodide from water; Low incidence of Hypothyroidism
In what receptor type does autophosphorylation occur once the ligand is bound causing a signaling kinase cascade?
Receptor Tyrosine Kinases
What does hormone binding to the receptor generally induce?
Receptor activity: an "on/off" response
Nuclear Receptors
Receptor found in the nucleus or cytosol; Bind to hormones that can pass through PM; Binding triggers movement to the nucleus and gene expression
After occupied Steroid receptors have released their chaperone proteins and exposed their DNA-binding domain (zinc-fingers), what occurs?
Receptors translocate to nucleus and form dimers with other receptors; Additional proteins complex with receptors to form complete transcriptional apparatus
What is the function of Type I deiodinase?
Recycle tyrosine and iodide in follicular cells
What is the consequence of Atrial Natriuretic Peptide's (ANP) inhibition of the release of Renin, production of Aldosterone, and uptake of Na+ in kidney?
Reduction in blood volume and pressure
5α reductase
Reduction reaction at C5 to lose double bond in ring A
Ligand-binding domain of Steroid nuclear receptors
Region where hormone binds to receptor; Hetero- or homo-dimerization; Regulates nuclear translocation; Associates with heat-shock proteins
DNA-binding domain of Steroid nuclear receptors
Region where receptor recognizes DNA at specific Hormone Response Element; Dimerization
What is the main purpose of T3?
Regulate basal metabolic processes
A specific neurotransmitter may ______ one type of tropic hormone and ______ another depending on how the synapses are connected.
Regulate; Inhibit
What are the Type 2 hormones', GH, PRL, and CS, common effects related to?
Related to structural similarity
Activin and Inhibin are closely ______ protein complexes with nearly ______ biological effects.
Related; Opposite
What is the size of the Fetal Zone of the adrenal gland of a fetus?
Relatively large
What are examples of Neurohormones?
Releasing hormones
What 2 hormone types are categorized by impact on tropic hormone release?
Releasing hormones (RH), Release-inhibiting hormones (RIH)
Phase 1 Metabolism of Steroid hormones
Remove or reduce side chains or attached groups on base structure; Can involve REDOX reactions
What are 2 repressors for Vasopressin (AVP) release? What are their 4 consequences?
Repressors: 1) Decrease in blood osmotic concentration 2) Increase in blood pressure Consequences: 1) Decreased water reabsorption 2) Diuresis 3) Homeostatic increase in blood osmotic concentration 4) Decreased blood pressure
The Type 2 hormone Prolactin (PRL) is involved in _______, ______, and _______.
Reproduction; Growth; Osmoregulation
Glucocorticoids, besides having a function in energy metabolism, also have actions in ______ and ______.
Reproduction; Immune system function (anti-inflammatory actions)
What is a major negative outcome of Cystic Ovarian Disease (COD) in cattle?
Reproductive dysfunction causes extended calving intervals, which results in economic loss
U- or J-shaped Curves
Response at low dose is different than at higher doses
Hormesis
Responses in organisms often show U- or J-shaped curves; Often a consequence of the animal's ability to metabolize the bioregulator
What is the Pineal Gland's main function?
Responsible for maintaining seasonal and circadian biological rhythms
What are thyroid hormones' effect on metabolism?
Responsible for strong, immediate and short-lived increase in cellular metabolism leading to non-shivering thermogenesis
What is the active hormone of insulin?
Resulting molecule of A and B peptides connected by disulfide bonds after C-peptide is cleaved
The symptoms of Hypothyroidism are ______ with therapy.
Reversible
Because T3 and T4 are hydrophobic, and thus not very soluble in blood, how are they transported through the blood?
Reversibly bound to transport proteins, allowing them to be released when needed and forming a ready reservoir of thyroid hormones
Where are Peptides and Protein hormones synthesized in the cell?
Rough Endoplasmic Reticulum (RER)
Ovarian follicles
Roughly spherical aggregations of cells including the oocyte, follicle (granulosa) and stroma (theca) cells
What animals have a Cotyledonary placenta?
Ruminants
The mechanism to maintain the CL during pregnancy by blocking lutelolytic hormone (PGF2α) is utilized by what 2 species mentioned?
Ruminants, Pigs
Ovulation phase of estrous cycle
Rupture of the mature follicle and release of oocyte
What gene causes male development? Where is it found?
SRY gene; Y chromosome
What are Pheromones (Exocrines/Semiochemicals) target?
Same species
Thyroglobulin (Tgb) acts as _______ in Thyroid hormone synthesis.
Scaffolding
Law or Principle
Scientific theory that has been accepted with certainty
What is one of several psychiatric disorders associated with melatonin mentioned?
Seasonal Affective Disorder (SAD)
Parathyroid Glands
Secrete a hormone important in the regulation of calcium ion concentrations in body fluids
Gonads
Secrete hormones affecting growth, metabolism, and sexual characteristics
Adrenal Glands
Secrete hormones involved with stress
Kidneys
Secrete hormones that regulate blood cell production and the rate of calcium and phosphate absorption by the intestinal tract
What is the function of Parathyroid glands?
Secrete parathyroid hormone which functions to regulate calcium homeostasis
Endocrine Glands
Secrete products directly into blood stream; Glands used by the endocrine system; Internal secretion
Exocrine Glands
Secrete products into DUCTS that carry them to other organs or outside the body (Ex. sweat glands); External secretion
What secretes the Catecholamines Norepinephrine and Epinephrine?
Secreted by Adrenal medulla into blood
Where is Inhibin produced in males?
Secreted by Sertoli cells
Digestive Tract
Secretes hormones involved in glucose metabolism and appetite
Thymus
Secretes hormones involved in immune response
Heart
Secretes hormones involved in regulation of blood volume
Hypothalamus
Secretes hormones involved in the control of hormone secretion by the anterior pituitary gland
Pancreas
Secretes hormones regulating the rate of glucose uptake and utilization of body tissues
Thyroid Gland
Secretes hormones that affect metabolic rate and calcium levels in body fluids
Pineal Gland
Secretes melatonin, which affects reproductive function and helps establish circadian rhythms
Pituitary Gland
Secretes multiple hormones that regulate the endocrine activities of the adrenal cortex, throid gland, and reproductive organs, and a hormone that stimulates melanin production
If fertilization is successful and implantation occurs, what phase of the Uterine cycle will continue throughout pregnancy?
Secretory phase
In the case of successful fertilization, what phase of the Uterine cycle does the uterus remain in for the duration of the pregnancy?
Secretory phase
What are Exocrines or Semiochemicals target?
Select cell types (e.g., sweat gland to skin) then ultimately, other animals
Where is the site of Spermatogenesis?
Seminiferous tubules
Radioimmunoassays (RIA) are very ______ and ______.
Sensitive; Quantitative
What must all chemical signals reaching the gametes in males pass through?
Sertoli cells
What produce Androgen-Binding Proteins (ABP)?
Sertoli cells
How are Sertoli cells "Nurse cells?"
Sertoli cells nurture developing gametes through stages of spermatogenesis
How many days are usually required to adjust to new environment when experiencing Circadian Dysrhythmia (jet lag)?
Several days
_____ _____ in the brain are related to the differing reproductive functions in males and females, puberty, and regulation of reproductive cycles and reproductive behavior.
Sex dimorphisms
What is an example of a hormone receptor that forms Homodimers before binding to DNA?
Sex steroids: Progestogens, Androgens, Estrogens
What is believed to be the root cause of all sex determination now?
Sex-determining genes
The Thyrotrope cell type found in the Pars distalis does not vary with _____ or ______.
Sex; Age
Estrogens may also influence ______ in males.
Sexual behavior
Idiopathic cause of Precocious Puberty
Sexual development and body growth appear normal, but accelerated; Reproduction may be possible
What is the medial preoptic area called pertaining to sexual dimorphism?
Sexually Dimorphic Nucleus (SDN)
What are some examples of animals that are seasonally polyestrus short day breeders?
Sheep, goat, doe, elk
Generally, positive feedback is important for ______-term events, but can be detrimental over longer time periods, even leading to the death of the organism.
Short (Ex. Job stress leads to sustained elevated blood pressure which damages blood vessels and increases risk of stroke)
How long are the final bioactive nonapeptide hormones after synthesis and removal of signal molecules and Neurophysin?
Short; 9 AA
What is the half-life of T3? T4?
Shorter (24hr); Longer (7 days)
What is the GnRH secretion pattern resulting from the Tonic center?
Shorter and lower concentrations than Surge center secretions
What are 3 factors that facilitate maturation and maintenance of sperm in the epididymis?
Sialic acids, glycerlphosporyl-choline, carnitine
Prepropeptide = ______ + ______
Signal molecule + Propeptide
Chorionic Gonadotropin (CG)
Signal needed for prolongation of Corpora luteal function in humans (hCG for humans)
How is Chorionic Gonadotropin (CG) different in horses?
Similar hormone called eCG (equine Chorionic Gonadotropin) or Pregnant Mare Serum Gonadotropin (PMSG); eCG is NOT made by embryo, only placenta
What are the treatments for Hyperthyroidism in cats?
Similar to humans: Drugs, radioactive iodine, surgery
Monoestrous
Single estrous period within a year; Ex. Bears, foxes, wolves (higher predators)
What is the structure of the Type 3: Small peptide hormone Adrenocorticotropin (ACTH)?
Single peptide chain of 39 AAs
Alveoli
Site of milk synthesis; Clusters of glandular epithelium or secretory cells
Seminiferous Tubules
Site of spermatogenesis
Thyroid hormones are critical for the normal development of ______ and ______ tissues.
Skeletal; Muscle (GH)
Morphological (Endocrine) control of color change
Slower response; Under endocrine control
Eicosanoids are ______ ______.
Small lipids
Neurohormones are typically ______ ______ of _____ amino acids.
Small; Peptides; 3-44 AAs
On what size hormones do G Protein-Coupled Receptors (GPCR) work with?
Smaller proteins
The Oxytocin-like peptides found in the Pars nervosa are important in ______.
Smooth muscle contraction
What is the unique divergent Type 2 hormone found in Teleost fish?
Somatolactin (SL)
What is the primary CONTROLLER of GH release?
Somatostatin (SST) or Growth hormone-release inhibiting hormone
How does the HPA axis in spawning salmon compare to Cushing's Syndrome?
Spawning salmon adrenal gland: Hyperplasia, degeneration Cushing's Syndrome adrenal gland: Hyperplasia, tumors
Chromatophores
Specialized pigment cells responsible for color patterns
What is the signal molecule found in the Prepropeptide? What is its function?
Specialized terminal sequence of AA; Directs prepropeptide to RER where translation resumes
What accumulate around the specialized pits involved in cell signal down-regulation? Why?
Specific proteins; Mediate endocytosis
In an Enzyme-Linked Immunoabsorbant Assay (ELISA), the primary antibody is ______ and the secondary antibody _______. Detection is by a ______ method.
Specific to the target; Targets the primary antibody; Colorimetric
There are no FSH receptors on ______, therefore how are the effects of FSH accomplished?
Spermatogonia; Control is via paracrine factors released from Sertoli cells, which DO have FSH receptors
How is spermatogenesis unique concerning germ cells?
Spermatogonium are constantly renewed for continual spermatogenesis
What is the treatment for Hyperaldosteronism?
Spironolactone, a K+ sparing diuretic, Aldosterone antagonist; Blocks Aldosterone's receptors
Most all species gestation lengths allow them to give birth at what time of the year?
Spring
The Vomeronasal organ is an auxiliary olfactory sense organ that contains ______ receptors that are especially responsive to ______.
Steroid; Pheromones
What hormones does the human fetal adrenal gland produce at birth? What are these hormones' function?
Steroids: Cortisol and DHEA; Cortisol induces lungs to produce surfactants in preparation for air breathing
What is the primary function of Oxytocin (OXY)?
Stimulate smooth muscle contraction
How does Prolactin (PRL) accomplish its lactogenic effect on mammary glands?
Stimulates DNA synthesis, cell proliferation, and synthesis of milk proteins, free fatty acids, and lactose in mammary gland
How does Aldosterone act at the kidney?
Stimulates Na+ reabsorption into blood and K+ secretion into urine; Involves the Renin-angiotensin System
What is the main action of the Type 3 hormone Adrenocorticotropin (ACTH)?
Stimulates adrenal cortex to secrete glucocorticoids to alter protein and carbohydrate metabolism
Besides acting in gamete preparation, what is another action of FSH? Where does this action occur more so and why?
Stimulates conversion of testosterone to estradiol by increasing activity of aromatase in both males and females; Especially in male brain- aggression and territorial behaviors
What is FSH's function during the Follicular phase of the estrous cycle?
Stimulates development of primordial follicles into primary follicles
In the 2-cell model of steroidogenesis in the ovaries, what is FSH's function?
Stimulates expression of aromatase for conversion of androgens to estrogens
What is the action of the Type 3 tropic hormone Lipotropin (LPH)?
Stimulates lipolysis in adipose tissue; Ex. Hydrolysis of fats to free fatty acids; No evidence directly linking LPH to lipid metabolism
Adrenocorticotropin (ACTH) regulation is under _____ control.
Stimulatory
Regulation of FSH and LH synthesis and release is under ______ control.
Stimulatory
Regulation of TSH secretion is under _______ control.
Stimulatory
The regulation of Corticotropin is under ______ control.
Stimulatory
Thyroid-Stimulating Hormone's (TSH) main control system is ______.
Stimulatory
Gonadotropins' (GTH- FSH/LH) main control system is ______.
Stimulatory (GnRH)
Growth Hormone's (GH) main control system is ______.
Stimulatory and Inhibitory
Regulation of GH release is under ______ control.
Stimulatory and Inhibitory
MAO: Monoamine oxidase
Stops process; Enzyme that degrades Catecholamines in neurons by deamination
What is an example of the activation of hormone receptors triggering the RELEASE of a second messenger molecule?
Stored Ca²⁺ released from Endoplasmic Reticulum
Corticosteroids are not ______ in the adrenal cortex, rather they are ______ as they are synthesized.
Stored; Released
It is a common observation that _____ animals are more susceptible to disease.
Stressed
What is one of corticosteroid's main functions in many non-mammalian vertebrates? Why is this action important?
Strong mineralcorticoid activity such as salt transport and osmotic balance; Involved in adaptation to external environment (Ex. migrate salmon, birds)
Within each hormone type of the pituitary tropic hormones there is substantial overlap in chemical ______ and in some cases overlap in ______.
Structure; Biological activity
If Cushing's Disease is detected early in horses, the therapy is usually _______.
Successful
Where are the adrenal glands found?
Superior to the kidneys (Ad-renal)
What are FSH and LH's function during the Follicular phase of the estrous cycle?
Support continued follicle development
Theory
Supported by preponderance of data; Reexamined and modified as necessary
What are daily circadian rhythms set by?
Suprachiasmatic nucleus (SCN) in hypothalamus
What kind of GnRH releasing center is present only in females?
Surge center
In most every species, what proceeds the LH/FSH surge?
Surge in estrogen
What is the primary treatment of Cryptorchidism?
Surgery; Usually during infancy
Goiter
Swelling of the thyroid gland; Associated with Hyperthyroidism and Hypothyroidism (Hypo more common)
What is one form of Pure gonadal dysgenesis (XY or XX)? What are its clinical signs?
Swyers syndrome: XY; Externally female, functionless gonads, no puberty, requires hormone replacement
______ acts on the ______ to produce Catecholamines Epinephrine and Norepinephrine.
Sympathetic Nervous System; Adrenal Medulla
Feline Cushing's
Symptoms very subtle; Most frequently discovered in cats with difficulty maintaining insulin sensitivity
Medications can be used to treat _______ of Cushing's Disease, but not the _______.
Symptoms; Primary cause
Where are Neurotransmitters found (compartment)? What is their target?
Synaptic space; Postsynaptic neuron
Hypothyroidism
Syndrome resulting from thyroid hormone deficiency, resulting in generalized slowing down of metabolic processes
Thyrotoxicosis
Syndrome that results when tissues are exposed to high levels of circulating thyroid hormones
How is Chorionic Gonadotropin (CG) different from the pituitary gonadotropins (GTHs)?
Synthesis and release of Chorionic Gonadotropin (CG) is not regulated by steroid negative feedback like pituitary GTHs
Where are Leukotrienes produced? Why?
Synthesized and released by WBCs; In response to injury
What is Dexamethasone?
Synthetic glucocorticoid; Mimics cortisol; Negative feedback on pituitary; Cannot cross blood/brain barrier, thus only a test of pituitary function
When in doubt, use the ______ name for Steroid nomenclature.
Systemic (IUPAC)
What is the biologically active form of Thyroid hormone?
T3 (Triiodothyronine)
What causes the feedback effects of T4?
T3 (after deiodination in thyrotropes)
Why is T3 the primary bioactive form of Thyroid hormone?
T3 has higher affinity for thyroid hormone receptor, thus it is much more potent than T4
Most thyroid hormone produced is ______.
T4
What is often considered a prohormone for T3?
T4
What is the major thyroid hormone in circulation?
T4
Levels of T___ rise dramatically during Metamorphosis (along with cortisol), whereas T___ remains low.
T4 (biologically active in metamorphosis); T3
What does T4 lead to in salmon smoltification?
T4 leads to deposition of guanine in scales, giving fish silvery appearance
There is more T___ circulating in the blood and more T___ within the cells.
T4; T3
About 50% of circulating T___ is eventually converted to T___ with slightly different _____ to form ______.
T4; T3; Structure; Reverse T3 (rT3)
T__ is more tightly bound than T__, thus T__ is more readily eliminated.
T4; T3; T3
What is the major Thyroid hormone in circulation? How is it transported?
T4; Transported in blood by Thyroid Transport Proteins, which provide ready pool of hormones for release
Why is the metabolism of T4 to form TETRAC and T3 to form TRIAC desirable?
TETRAC and TRIAC are very water-soluble and can thus be excreted in urine or bile
What family do both Activin and Inhibin protein complexes belong to?
TGF-β protein superfamily
What hormone regulates the expression of the Thyroglobulun (Tg) gene?
TSH
Where are Steroids typically metabolized?
Target cell, Liver
Immunohistochemistry (IHC)
Tell where hormone is located in cell; Antibody detection of particular hormones in cells or tissues
A Hypothesis must be ______.
Testable
Testicular Feminization syndrome
Testes are normal and secrete testosterone; Congenital lack of androgen receptors in tissues causes external appearance of a woman (Secretes testosterone, but no receptors)
Androstenedione (C19) + 17β-HSD = ______ Androstenedione (C19) + Aromatase = ______
Testosterone (C19): C17 ketone converted to hydroxyl Estrone (C18): A ring becomes aromatic
Androstenediol (C19) + 3β-HSD = ______
Testosterone (C19): Ketone at C3
What stimulates meiosis in primary spermatocytes?
Testosterone (T) regulates function of Sertoli cells causing meiosis
What is the major circulating androgen in mammals?
Testosterone; Androstenedione and dihydro-testosterone (DHT) are also present in significant amounts
What do the endosomes involved in thyroid hormone release from the thyroid follicle contain?
Tg with bound T3 or T4; Colloid fluid
Endocrine systems with a Type II organization do NOT involve _______.
The brain
What are the 4 T's of correct hormone function?
The right TISSUE must be targeted at the right TIME with the right TYPE of hormone at the right TITER or concentration (Tissue, Time, Type, Titer)
Where does most of the 2-cell steroid synthesis pathway occur in females? What is its result?
Theca cells; Generate androgens, primarily androstenedione, under stimulation by LH
What is the therapeutic use protocol for Prednisone (glucocorticoid)?
Therapy uses the lowest possible dose for the shortest period of time
What does it mean to say that some animals exhibit indeterminate growth?
They keep growing in size their entire lifespan (instead of finite growth)
How do the oral contraceptive pills using only Progestin function? What is a negative effect of this method?
Thickening of cervical mucus, inhibiting sperm travel; Inconsistently inhibit ovulation
Adenohypophysis: Pars tuberalis (location)
Thin layer of cells that project above anterior pituitary (wraps around stalk); In contact with median eminence
Independent Variable
This is the thing you control as the experimenter
What protein attaches to tyrosine in follicle colloid during thyroid hormone synthesis?
Thyroglobulin (Tg)
Persistent health problems are associated with ______ hormone deficiencies (e.g. goiter).
Thyroid
Thyroglobulin (Tg) is made and used entirely within the _______.
Thyroid gland
What endocrine tissue is organized into follicles, a spherical mass of one cell layer surrounding fluid-filled space (lumen)?
Thyroid gland
What is the primary treatment for Hypothyroidism in dogs?
Thyroid hormone replacement (generally very successful)
What determines the level of TSH secretion for normal thyroid gland activities? How is this accomplished?
Thyroid hormones (T4, T3); Hypothalamus adjusts level through TRH secretion in response to environmental cues
GH cooperates with several other hormones. What hormone(s) maintain cells in a GH-responsive state?
Thyroid hormones (androgens, estrogens to lesser extent)
What bioregulators are essential to proper development and differentiation of ALL cells of the human body?
Thyroid hormones (lots of Cross Talk)
What is the action of thyroid hormones in amphibians?
Thyroid hormones induce metamorphosis of amphibians from aquatic larva to (semi)terrestrial form
Thyrotrope: Hormone secreted
Thyroid-stimulating hormone (TSH)
What is the stimulatory hormone that regulates Thyroid-stimulating hormone (TSH) release?
Thyrotropin-Releasing Hormone (TRH)
What is an example of an amino acid, peptide and protein bioregulator made up of a small peptide?
Thyrotropin-releasing hormone
T4 = ______
Thyroxine
What forms between Sertoli cells found in Seminiferous tubules?
Tight junctions forming the blood/testis barrier
Beta (β) spatial conformation
Towards you (Solid wedge); In front of the plane
What is another name for Plummer's disease?
Toxic multi-nodular goiter (TSH-independent)
Marine-Lenhart Syndrome
Toxic multi-nodular goiters consisting of multiple aggregates of SMALL, hyperactive follicles
Hormones can regulate gene expression through interaction with ______.
Transcription Factors (TFs)
Homodimers of thyroid hormone receptors (TR) can form, but produce little _______.
Transcriptional response
Smoltification
Transition between Parr to Smolt; Complex process involving hormones including T4, cortisol, and prolactin
Cell-surface Receptors
Transmembrane proteins which, when external portion binds to hormone, initiate a cell signaling cascade
Vas deferens (ductus deferens)
Transport sperm from Epididymis in anticipation of ejaculation
How is T4, the major thyroid hormone in circulation, transported in the blood?
Transported by Thyroid Transport Proteins, which provide ready pools of hormones for release
What is the treatment for Secondary Amenorrhea?
Treatment of the causative endocrine disorder; Treatment usually reverses condition
Upon reaching the target cell, what is a regulatory hormone's action?
Trigger synthesis or inhibit synthesis of a particular tropic hormone
What are 2 triggers for Vasopressin (AVP) release? What are their 4 consequences?
Triggers: 1) Increase in blood osmotic concentration 2) Decrease in blood pressure Consequences: 1) Increased water reabsorption 2) Antidiuresis 3) Decrease in blood osmotic concentration 4) Increased blood pressure
T3 = _______
Triiodothyronine
What is the structure of Thyrotropin-Releasing Hormone (TRH)?
Tripeptide (3 AA)
What produces Chorionic Gonadotropin (CG) in humans upon pregnancy?
Trophoblast cells of the developing embryo even before implantation occurs
Each regulatory hormone is named for the ______ hormone it was first shown to influence.
Tropic
A very small amount of T3 makes it into blood circulation. (TRUE/FALSE)
True
Acromegaly is documented in many other species besides humans. (TRUE/FALSE)
True
Autoimmune Thyroiditis, a type of Hypothyroidism commonly found in dogs, will often start at puberty, but not be detected until loss of thyroid function later in life. (TRUE/FALSE)
True
Bioregulators communicate with other pathways such that one bioregulator system may influence the effectiveness of another. (TRUE/FALSE)
True
Even small changes in hormone release or function can lead to endocrine dysfunction. (TRUE/FALSE)
True
FSH and LH have relatively separate roles in males. (TRUE/FALSE)
True
Features of bioregulators are uniquely tied to their chemical composition. (TRUE/FALSE)
True
In general, tropic hormone release is controlled in a similar manner in other vertebrates (i.e. Releasing Hormones and Release-Inhibiting Hormones). (TRUE/FALSE)
True
In some species, steroid production by the Corpus luteum may depend on LH, prolactin (PRL) or both depending on the species. (TRUE/FALSE)
True
MIT is NOT used to make T3 in Thyroid hormone synthesis. (TRUE/FALSE)
True
Major features and operation of the HPG axis are largely similar among vertebrates. (TRUE/FALSE)
True
Negative Feedback Loops are necessary to maintain homeostatic balance in a changing environment, external or internal. Any disturbance (up or down) causes a homeostatic reflex to be activated to maintain within tolerable range of set point. (TRUE/FALSE)
True
Other Melanotropin (MSH) isotypes have been found (β-MSH and ϒ-MSH), but their physiological role remains unclear. (TRUE/FALSE)
True
Other glands, especially the prostate, add fluid secretions to the sperm and epididymal secretions to form semen. (TRUE/FALSE)
True
Pertaining to Cross Talk, all of the messages in the body are integrated to fine tune the cellular response to a hormone. TRUE/FALSE)
True
Pituitary dwarfism can occur in other species besides humans. (TRUE/FALSE)
True
Releasing hormones normally don't interact with other "tropes." (TRUE/FALSE)
True
Some transcription factors are steroid receptors, activated by ligand binding of hormones. (TRUE/FALSE)
True
Some variation in sequence of puberty events is normal. (TRUE/FALSE)
True
Sometimes receptors are active when not bound to a ligand and are turned off or inactivated when bound to a hormone. (TRUE/FALSE)
True
Steroid receptors, whether found in the cytoplasm or nucleus, are both called Nuclear Receptors. (TRUE/FALSE)
True
The Carbon Monoxide (CO) bioregulator's biological function not well understood at this time. (TRUE/FALSE)
True
The Endocrine System is involved in chemical regulation of virtually all biological phenomena in animals and the molecular, cellular, organism and population level. (TRUE/FALSE)
True
The activity of the hypothalamus is influenced by a variety of exogenous environmental factors via the central nervous system. (TRUE/FALSE)
True
There are NO FSH nor androgen receptors on spermatogonia. (TRUE/FALSE)
True
Thyroid hormones are important for nervous system development. (TRUE/FALSE)
True
Unintended exposure to hormones or hormone-like chemicals can lead to changes in sex in wildlife. (TRUE/FALSE)
True
When Ca²⁺ concentrations spike within a cell many changes may occur. (TRUE/FALSE)
True
Intersex fish have gonad with male and female gametes and are often infertile. (TRUE/FALSE)
True (Best examples are largemouth and smallmouth bass)
Dwarf-like traits can be amplified through selective breeding in domesticated species, but this is NOT dwarfism. (TRUE/FALSE)
True (Ex. Brachiocephalic- short snout, Achondroplastic-short limbs)
After a some time, the Corpus luteum will degenerate and steroid production will decline, if not pregnant. (TRUE/FALSE)
True (Functional "life-span")
Thyroid hormones are responsible for maintaining a general state of "well-being" for many cells so that they are capable of maximal responses to other stimuli (TRUE/FALSE)
True (provide homeostasis)
In bony fishes, the structure of the thyroid hormone-producing follicle is similar to mammals. (TRUE/FALSE)
True (same deiodinases, similar mechanisms)
There are different estrous cycle patterns observed in different species of mammals. (TRUE/FALSE)
True; Ex. Polyestrus, seasonal polyestrus, monoestrus
What is the precursor for Indoleamines?
Tryptophan
In Indoleamine Synthesis, ______ becomes ______ which becomes ______.
Tryptophan; Serotonin; Melatonin
What are the 3 types of pituitary tropic hormones?
Type 1: Glycoproteins Type 2: Long peptide chains Type 3: Smaller peptides
What are the symptoms of Seasonal Affective Disorder (SAD)? (4)
Typical of depression; 1) Lack of energy 2) Difficulty concentrating 3) Withdrawal from social groups 4) Changes in eating habits
What is the precursor for Catecholamine synthesis?
Tyrosine
What is the precursor for Thyroid hormone synthesis?
Tyrosine
What is the precursor to thyroid hormone synthesis?
Tyrosine
What is the rate limiting step (slowest, controls) in Catecholamine synthesis?
Tyrosine hydroxylase (adds a hydroxyl group to the ring)
What is the biological action of Neurophysins?
Unclear; Possible carrier function to deliver nonapeptides to granules
Cretinism is a significant health problem in ______ (location).
Under-developed nations (Iodide deficient)
Reverse T3 (rT3) (STRUCTURE)
Understand
How many carbons can be attached to the side chain of a Steroid?
Up to 8
How long does it take from fertilization to implantation in humans?
Up to 9 days
Where does fertilization typically occur?
Upper third of oviduct (ampullary-isthmic junction)
What are the metabolites of Catecholamines excreted into?
Urine
What commonly occurs to cryptorchid horses?
Usually affected horses are gelded
How effective are medications at treating mild symptoms of Cushing's Disease in horses? Severe symptoms (e.g. laminitis, immune problems)?
Usually effective; Generally ineffective
Plummer's disease
Usually occurs in older patients with history of multi-nodular goiter; Several large TSH-independent hyperactive follicles
What is another name for the Menstrual cycle in primates?
Uterine cycle
Bioassay
Utilizing animals or animal tissues to extrapolate the presence of an endocrine regulator
What, along with Thyrotropin-Releasing Hormone (TRH), activates Thyroid-stimulating hormone (TSH) secretion?
VIP; Neurohormone secreted by hypothalamus
The thyroid gland is highly ______. How is this important?
Vascularized; Facilitates delivery and release of hormones through circulation
What, along with Thyrotropin-Releasing Hormone (TRH), activates Thyroid-stimulating hormone (TSH) secretion?
Vasoactive Intestinal Peptide or VIP, a neurohormone
The nonapeptide preprohormones Prepropressophysin yields ______, while Preprooxyphysin yields ______.
Vasopressin; Oxytocin
What carries blood containing tropic hormones released by the anterior pituitary away?
Venus portal system
The Pars tuberalis is present in all _______ ______.
Vertebrate Tetrapods
All ______ brains have a hypothalamic region, which is ______ in size.
Vertebrate; Small
Somatotropes are large secretory ______.
Vesicles
How are Corticosteroids transported in the blood?
Via Corticosteroid Binding Globulin (CBG)
How does circulating TSH reach thyroid follicles?
Via well-developed network of capillaries
What is an example of a hormone receptor that forms Heterodimers before binding to DNA?
Vitamin D
Who first defined Homeostasis? When?
Walter B. Cannon; 1929
Aquaporins
Water channels in the PM
Dependent Variable
What you measure; Variable that changes as a result of modification of the independent variable
When are sperm cells fully mature?
When they arrive in the Body of the Epididymis
When will Chorionic Gonadotropin (CG) appear in maternal blood?
Within a few days after fertilization
Myxedema is more common in ______ than ______.
Women; Men
Thyroiditis is more common in _____ than _______.
Women; Men
Turner's syndrome
XO; Loss of one sex chromosome; Female phenotype; Infertile; Other anatomical defects, cardiovascular, and kidney disorders
Klinefelter's syndrome
XXY; Extra X chromosome; Infertile; May suffer from mental retardation
Pure gonadal dysgenesis
XY or XX; Normal chromosomes, but defects of specific gene, often SRY gene (found on Y chromosome)
What are the 3 primary hormones produced in the Adrenal Cortex?
Zona glomerulosa: Aldosterone Zona fasciculata: Glucocorticoids Zona reticularis: DHEA (androgen)
The ______ ______ secretes Aldosterone independently of ______ from the pituitary gland.
Zona glomerulosa; ACTH (but DOES facilitate response)
What is the outer protective membrane of a developing ovum?
Zona pellucida
Fetal Zone of the adrenal gland
Zone of adrenocortical cells between cortex and medulla; Often found in primates and some other mammals (not rodents)
The concept of Homeostasis now includes all ______.
bioregulation
Second messenger molecules activate intracellular signaling cascades which direct the cellular response. What does cAMP trigger? Ca²⁺?
cAMP: Triggers kinase cascades by activating protein kinase A Ca²⁺: Binds to Calmodulin which triggers hormone release
In horses, ______ is produced by placental structures called ______ _______ later in pregnancy.
eCG; Endometrial cups
Why was the fish Type 2 hormone Somatolactin (SL) given its name?
structure was similar to other Type 2 hormones Prolactin (PRL) and Somatotropin (GH)
In Morphologically (Endocrine)-controlled color changes, what is the hormone responsible for the color change?
α-MSH
What subunit is identical in all three Type 1 hormones (Glycoproteins)? Which subunit is different? How is this important?
α-subunit; β-subunit; Confers hormone specificity
What is the only ∆-pathway employed in the testes?
∆4-pathway
