CH 16 ENDOCRINE

Graves disease

(with associated exophthalmos) develops due to excess thyroid hormone

Hormone Release

-Blood levels of hormones +Are controlled by negative feedback systems ^Increased hormone effects on target organs can inhibit further hormone release +vary only within narrow, desirable range +vary with hormone release as modulated by: ^Endocrine gland stimuli ^Nervous system modulation

Humoral Stimuli

-Changing blood levels of ions and nutrients directly stimulate secretion of hormones -Example: Ca2+ in blood +Declining blood Ca2+ concentration stimulates parathyroid glands to secrete PTH (parathyroid hormone) +PTH causes Ca2+ concentrations to rise, and stimulus is removed

Plasma Membrane Receptors and Second-Messenger Systems

-G-proteins and Cyclic AMP -PIP2-calcium signaling mechanism +Hormone-activated G protein activates a different effector enzyme: phospholipase C +Activated phospholipase C splits membrane protein, PIP2, into two second messengers: ^Diacylglycerol (DAG) activates protein kinases ^Inositol trisphosphate (IP3) causes Ca2+ release from intracellular storage sites +Calcium ions act as another second messenger ^Ca2+ alters enzyme activity and channels, or binds to regulatory protein calmodulin ^Calcium-bound calmodulin activates enzymes that amplify cellular response -Other signaling mechanisms +cGMP (cyclic guanosine monophosphate) is second messenger for selected hormones +Other hormones work without second messenger system ^Example: insulin receptor is a tyrosine kinase enzyme that autophosphorylates upon insulin binding *Activated tyrosine kinases provide docking sites for relay proteins that trigger cell responses

Hormone Activity

-Hormones reach their target via the blood stream -Hormones travel throughout the entire body -Hormones will only affect target cells that possess specific protein receptors for the hormone -Receptors are continually being synthesized and broken down -Receptors may be down-regulated in the presence of high concentrations of hormone -Receptors may be up-regulated in the presence of low concentrations of hormone

basal (Actions of T3 & T4)

-Increase _______ metabolic rate (BMR) -Help maintain normal body temperature -Stimulate protein synthesis -Increase the use of glucose and fatty acids for ATP production (gluconeogenesis, lipolysis & glycogenolysis) -Upregulate beta (β) receptors to catecholamines (NE & E) -Work with hGH and insulin to accelerate body growth

Intracellular Receptors and Direct Gene Activation

-Lipid-soluble steroid hormones and thyroid hormone can diffuse into target cells and bind with intracellular receptors -Receptor-hormone complex enters nucleus and binds to specific region of DNA -Helps initiate DNA transcription to produce mRNA -mRNA is then translated into specific protein +Proteins synthesized have various functions +Examples: metabolic activities, structural purposes, or exported from cell

Hormone Action

-Not all Hormones circulate through the body -Hormones that don't circulate are local hormones -Local hormones can act on: +Nearby cells: paracrine hormones, or +They can act on the same cell that secretes them: autocrine hormones.

How a target cell responds to a hormone is based on

-The hormone's concentration in the blood -The number of hormone receptors on the target cell -Influences exerted by other hormones -Some hormones work more effectively when a second hormone is present to assist them (synergistic effect) -Some hormones oppose the action of others (antagonistic effect)

Aging and the Endocrine System

Aging brings about changes in the levels of most hormones -Some hormone levels increase while some decrease -Levels of other hormones, like epinephrine and norepinephrine, remain the same Histologically, most endocrine glands reduce in size and contain increasingly more fibrous connective tissue with age

acini, pancreatic islets

Almost all of the exocrine cells of the pancreas are arranged in clusters called ______. ______ produce digestive enzymes that are delivered to the gastrointestinal tract through ducts Scattered among the acini are clusters of endocrine tissue called ___________ _______ (islets of Langerhans) -The islets contain secretin cells -The islets include 4 types of cells that secrete different hormones: 1) Alpha (A) cells - glucagon 2) Beta (B) cells - insulin 3) Delta (D) cells - somatostatin 4) F cells - pancreatic polypeptide

Posterior pituitary

Also called Neurohypophysis - PP gland does not synthesize any hormones, but stores and releases from axon terminals two hormones produced by the neurosecretory cells of the hypothalamus: +Oxytocin (OT) +Anti-diuretic hormone (ADH) -Axons from the neurosecretory cells form the hypothalamohypophyseal tract

Endocrine Glands

Certain organs and tissues that are not part of the endocrine system also secrete hormones. -They contain secreting cells -Secreting cells can be found in: the hypothalamus, thymus, pancreas, ovaries, testes, kidneys, Stomach, liver, small intestine, skin, heart, adipose tissue and placenta

Mechanisms of Hormone Action

Hormones act based on their chemical structure and composition as well as charge Hormones are classified as either lipid-soluble (steroid hormones, thyroid hormones, nitric oxide) or water-soluble (amine hormones, peptide and protein hormones, eicosanoid hormones) -Water-soluble hormones circulate freely in blood -Lipid-soluble hormones circulate in blood bound to transport proteins -Lipid-soluble hormones cross the plasma membrane freely and do not require a receptor on the plasma membrane -Lipid-soluble hormones generally interact with nuclear receptors and regulate gene expression

Hormonal Stimuli

Hormones stimulate other endocrine organs to release their hormones -Hypothalamic hormones stimulate release of most anterior pituitary hormones -Anterior pituitary hormones stimulate targets to secrete still more hormones -Hypothalamic-pituitary-target endocrine organ feedback loop +Hormones from final target organs inhibit release of anterior pituitary hormones

anterior pituitary gland secretes:

Human growth hormone (hGH) Thyroid-stimulating hormone (TSH) Follicle-stimulating hormone (FSH) Luteinizing hormone (LH) Prolactin (PRL) Adrenocorticotropic hormone (ACTH) Melanocyte-stimulating hormone (MSH) The release of releasing hormones by the hypothalamus is regulated via Negative feedback loops.

parathyroid glands

Located on the posterior aspect of each lobe of the thyroid gland are 2 ___________ _______(one inferior and one superior)

target cells

Most hormones circulate through the blood and bind to receptors on "___________ ______" Though hormones circulate systemically, only cells with receptors for that hormone are affected **Target cells: tissues with receptors for a specific hormone -Hormones alter target cell activity Neurotransmitters also bind to receptors on "target" cells

Neural Stimuli

Nerve fibers stimulate hormone release -Sympathetic nervous system fibers stimulate adrenal medulla to secrete catecholamines

Nervous System Modulation

Nervous system can make adjustments to hormone levels when needed -Can modify stimulation or inhibition of endocrine glands Nervous system can override normal endocrine controls -Example: under severe stress, hypothalamus and sympathetic nervous system override insulin to allow blood glucose levels to increase +Prepare body for "fight or flight"

Chief, Oxyphil

Parathyroid glands contain 2 types of cells: 1) ________ cells (principal cells) that produce parathyroid hormone (PTH) 2) _________ cells whose function is not known in normal parathyroid glands, but which secrete excess PTH in cases of parathyroid cancer

Mechanisms of Hormone Action

Responses to the same hormone may vary depending on the hormone itself and the target cell The response may be: -Synthesis of new molecules -Changing permeability of the cell membrane -Stimulating transport of a substance into or out of the cell -Altering the rate of metabolic actions -Causing contraction of smooth or cardiac muscle

negative feedback

Secretion of insulin and glucagon are controlled by ___________ ___________

pineal gland

The ________ _______ is attached to the roof of the third ventricle of the brain and secretes melatonin -Melatonin helps to regulate the body's biological clock

adrenal

The ________ glands are covered by a connective tissue capsule Each gland is divided into two regions: 1) The outer cortex 2) The inner medulla The cortex is divided histologically into 3 regions: 1)The zona glomerulosa 2) The zona fasciculata 3) The zona reticularis

nervous, endocrine

The _________ AND ___________ SYSTEMS act together to coordinate all systems of the body

adrenal glands

The _________ __________ (suprarenal glands) are located on top of each kidney Blood supply: Each gland is supplied by the superior, middle and inferior suprarenal arteries, which arise from the inferior phrenic artery, abdominal aorta and renal artery respectively The medullary veins emerge from the hilum of each gland before forming the suprarenal veins, which join the inferior vena cava on the right side and the left renal vein on the left

thyroid

The _________ gland is a butterfly-shaped gland located inferior to the larynx and anterior to the trachea -It has right and left lateral lobes connected by an isthmus

thymus

The _________ is located behind the sternum between the lungs and produces thymosin, thymic humoral factor (THF), thymic factor (TF), and thymopoietin -These hormones promote maturation of the immune system's T cells

adrenal medulla

The __________ _________ is stimulated by sympathetic preganglionic neurons of the autonomic nervous system (ANS)

pancreas

The __________ is located in the curve of the duodenum -It is both an endocrine and exocrine gland

anterior, posterior (pituitary gland)

The ___________ lobe (adenohypophysis) makes up 75% of the weight of the pituitary gland and secretes 7 hormones The ___________ lobe (neurohypophysis) is made of neural tissue and releases two hormones made by the hypothalamus: ADH (vasopressin) and Oxytocin

hypothalamus, pituitary gland

The ____________ and ________________ ________ work together to control other endocrine glands -They are connected by the infundibulum

hypothalamus

The ________________ secretes releasing and inhibiting hormones that control the release of hormones by the pituitary gland -They reach the pituitary gland via the hypophyseal portal system

antidiuretic

The amount of ____________ hormone (ADH) secreted varies with blood osmotic pressure -ADH decreases urine output as part of a negative feedback loop where osmoreceptors in the hypothalamus monitor blood osmotic pressure +An increase in blood osmolarity causes an increase in ADH secretion +A decrease in blood osmolarity causes a decrease in ADH secretion Target organs: Kidneys, Sudoriferous glands, Arterioles

B

The flight-or-flight response produces all of the following except: a) increased heart rate and force of contraction b) dilation of vessels to the digestive organs c) increase in blood pressure d) decreased urinary activity e) increased glycogenolysis

DHEA,males,females

The major androgen secreted by the adrenal cortex is dehydroepiandrosterone (_______) -In _________, after puberty, the hormone testosterone is secreted in much larger quantities so DHEA has virtually no effect -In ___________, DHEA and other adrenal androgens play a major role in promoting libido and are converted to estrogens +In menopausal women, all female estrogens come from adrenal androgens

neurotransmitters,hormones

The nervous system releases _____________ ; the endocrine system releases __________

glomerulosa

The zona _____________ secretes hormones called mineralocorticoids used to regulate mineral homeostasis

gluco

The zona fasciculata secretes hormones called ______corticoids that affect glucose homeostasis

androgens

The zona reticularis secretes weak ____________ (hormones with masculinizing effects)

B

Which feature does not apply to the nervous system in comparison to the endocrine system? a) neurotransmitters released locally b) response could occur very quickly or it could be in hours c) effects seen on muscle cells, glands, and neurons d) mediator action is close to site of release e) very brief duration of action

C

Which gland or organ is not strictly classified as an endocrine gland? a) thyroid gland b) adrenal gland c) pancreas d) pineal gland e) pituitary gland

B

Which hormone is not matched correctly with its principal action? a) gastrin - increases stomach movement b) erythropoietin (EPO) - increases white blood cell production c) leptin - suppresses appetite d) atrial natriuretic peptide (ANP) - lowers blood pressure e) estrogens - prepare mammary gland to secrete milk

E

Which of the following hormones would increase in a laboratory animal after a thyroidectomy? 1. thyroid stimulating hormone (TSH) 2. triiodothyronine (T3)3. thyrotropin-releasing hormone (TRH) 4. thyroxine (T4) a) 1 only b) 2 only c) 3 only d) 4 only e) 1 and 3

A

Which of the following is not true of the prostaglandins? a) decrease pain sensitivity b) promote fever c) derived from arachidonic acid d) alter smooth muscle contraction

D

Which of the following is true when describing the permissive effect of a hormone? a) a permissive hormone can cancel out the effect of another hormone b) this means that two hormones have a greater effect than just one c) the hormone can act alone when having an effect on a tissue d) is usually the result of a second hormone's exposure on target cells

D

Which statement is not true of the interplay between PTH, Calcitonin, Calcitriol, and Ca++? a) calcitriol increases calcium absorption from foods b) PTH increases resorption of bone c) high blood calcium levels increases calcitonin release d) PTH decreases vitamin D levels e) PTH raises blood calcium levels

T3, T4

____ and ____ are synthesized and secreted in an 8 step process

Pituitary gigantism, acromegaly

________ ____________ and _______________ are caused by excess secretion of growth hormone

Gonads

_________ (ovaries and testes) produce gametes (oocytes and sperm respectively) Ovaries produce -two estrogens (estradiol and estrone) -progesterone -relaxin -inhibin Testes produce -testosterone -Inhibin

Exocrine,Endocrine

_________ glands secrete their products into ducts -None of these are hormones -Exocrine glands include sudoriferous (sweat) glands, sebaceous (oil) glands, mucous glands, digestive glands and several other throughout the body __________ glands secrete hormones -Endocrine glands do not have ducts, instead they secrete their hormones directly into the interstitial fluid that surrounds them -The hormones diffuse into the blood stream through capillaries and are carried to target cells throughout the body -Endocrine glands include the pituitary, thyroid, parathyroid, adrenal and pineal glands

Eustress

_________ is helpful, everyday stress that prepares us to meet challenges

Human growth

__________ __________ hormone (hGH) is the most plentiful anterior pituitary hormone -It is released in bursts every few hours by somatotrophs (cell in the anterior pituitary that release GH) -Their activity is controlled by two hypothalamic hormones: growth hormone-releasing hormone (GHRH) and growth hormone-inhibiting hormone (GHIH)

Chromaffin

__________ cells secrete epinephrine (adrenaline) and norepinephrine (noradrenaline) both of which are involved in the fight-or-flight response

Oxytocin

__________ is released in response to stretch placed on the cervix during child birth. Oxytocin affects the: -Mother's uterus - enhances contractions -Mother's breasts - stimulates milk production by the mammary glands in response to suckling

Calcitonin

__________ produced by the thyroid gland works in conjunction with PTH and calcitriol (1,25(OH)2D3, liver) to regulate calcium homeostasis

Hormones

____________ act in one of two ways, depending on their chemical nature and receptor location -Water-soluble hormones (all amino acid-based hormones except thyroid hormone) +Act on plasma membrane receptors +Act via G protein second messengers +Cannot enter cell -Lipid-soluble hormones (steroid and thyroid hormones) +Act on intracellular receptors that directly activate genes +Can enter cell

Distress

____________ is any type of harmful stress that may be damaging -The fight-or-flight response (first stage of the stress response) stimulates the body's resources to prepare for immediate activity -The resistance reaction is the second stage in the stress response and lasts longer than the fight-or-flight response +If this lasts too long, exhaustion will result

Aldosterone

____________ is the major mineralocorticoid secreted by the adrenal gland. It helps regulate sodium and potassium homeostasis -The renin-angiotensin-aldosterone (RAA) pathway controls secretion of aldosterone

Eicosanoids

_____________ are locally-acting hormones derived from the 20-carbon fatty acid arachidonic acid (AA) -Certain hormones stimulate cell growth and division -Several newly discovered hormones called growth factors are involved in tissue development, growth, and repair

Endocrine

_____________ system controls and integrates: -Reproduction -Growth and development -Maintenance of electrolyte, water, and nutrient balance of blood -Regulation of cellular metabolism and energy balance -Mobilization of body defenses Does so by releasing chemical messengers into the blood

Endocrine

______________ glands are stimulated to synthesize and release hormones in response to one of three stimuli: 1) Humoral stimuli 2) Neural stimuli 3) Hormonal stimuli

Hormones

_______________ are secreted in short bursts when needed Secretion is regulated by: -Signals from the nervous system -Chemical changes in the blood -Other hormones Most hormone regulation is achieved via negative feedback Only a few hormones operate via positive feedback.

Glucocorticoids

_________________ regulate glucose metabolism and energy production -Permissive hormones -Secretion of glucocorticoids (cortisol [hydrocortisone]-the most produced, cortisone and corticosterone) is regulated by negative feedback -They help control: +Protein breakdown +Glucose formation +Lipolysis +Resistance to stress +Inflammation +Immune responses

Follicular cells

are stimulated by TSH to produce thyroxine (tetraiodothyronine, T4) and triiodothyronine (T3) known as thyroid hormones

Goiter

is caused by a reduction in the production of thyroid hormone

Cushing's syndrome

is caused by excess secretion of glucocorticoids

Parafollicular cells

produce the hormone calcitonin to help regulate calcium homeostasis