HTHS 1111 Ch. 14 modules 1-
Most hormone systems work via negative feedback. For these systems to function correctly, there must be 3 things. What are these 3 things?
"Receptors" for the stimulus An "interpretation (control) center" An initiated "response" that reverses the stimulus
Describe the general purpose of the endocrine system.
"purpose" of endocrine & nervous system is regulating homeostasis. Through the use of mediator molecules, homeostatic mechanisms are strictly controlled. In the endocrine system the molecules involved are "hormones".
What 2 terms are important to know to understand the pituitary glands relationship with the hypothalamus?
-ADENO: means "gland"; so the relationship of the hypothalamus and anterior pituitary is a "gland to gland" relationship. The hypothalamus produces hormones that will circulate through a vascular connection with the anterior pituitary stimulating the release of another group of hormones from the anterior pituitary. So in other words; with these connections in mind, the hypothalamus produces regulating hormones that circulate down to the adenohypophysis and stimulate it to secrete its own hormones. -NEURO: means "nerve". To stimulate the neurohypophysis the hypothalamus sends nerve impulses to the neurohypophysis. These nerve impulses stimulate the neurohypophysis to secrete oxytocin and ADH.
What can cause hypersecretion?
-Excessive hormone production -Tumors of endocrine origin - causing excess hormone release. Benign or malignant. -Absence of normal feedback mechanisms.
What are the required steps for T3 and T4 synthesis?
-Iodine trapping -Synthesis of thyroglobulin (TGB) -Oxidation of Iodine: -Iodination of tyrosine -Coupling of T1 and T2 to make T3 and T4 -Pinocytosis and digestion of colloid -Secretion of thyroid hormones -Transport of T3 and T4 in the blood
Describe water-soluble hormone action. (NEED TO KNOW IMAGE ON PG 632)
-The hormone (1st messenger) attaches to receptors on the plasma membrane of the target cell. -Receptor-hormone complex is formed and activates a "G-protein" -G-protein then activates "Adenylate cyclase" -Adenylate cyclase converts ATP to cyclic AMP (cAMP) -cAMP is the "2nd messenger"in the cytoplasm. -cAMP activates 1 or more enzymes (protein kinases) which bring about the desired effect within the cell. REMEMBER: kinases phosphorylate (add a phosphate to) other molecules. -in this case, the phosphorylated molecules are proteins. Through phosphorylation, some proteins are activated and some are deactivated. -to limit the duration of the response, unless new hormone binds to the receptors, an enzyme called "phosphodiesterase" inactivates cAMP -NOTE: the 2nd messenger can act as activators, inhibitors or cofactors. -Ca++ is also a common 2nd messenger.
Target cells responsiveness depends on what?
-The hormone concentration -Number of receptors available to bind hormone -Influences of other hormones ie: permissive effect, synergistic effect, antagonistic effect
Describe lipid-soluble hormone action. (NEED TO KNOW IMAGE ON PG 631)
-The hormone diffuses through the lipid-bilayer of the target cell and binds to intracellular receptors. -This creates a "receptor-hormone complex" within the cytosol or nucleus. (ie: receptors can be in the cytoplasm or in the nucleus). -The hormone activates genes to bring about the desired effect (ie; turns specific genes on or off). so in other words, this "receptor-hormone complex" can alter the gene expression of the cell by turning the genes encoded by the cell's DNA on or off). -So, depending on the type of receptor the hormone binds to, it can be excitatory or inhibitory in the target cell. -The end result is the alteration of the cell's activity.
What can cause hyposecretion?
-Too little hormone production -Decreased hormone receptors -Second-messenger system defects -Lack of hormone precursors -Degraded hormones -Poor blood flow (ischemia)
What do the thyroid hormones do for the body?
-regulates oxygen use -increases the basal metabolic rate (BMR) -Increases protein synthesis -increases carbohydrate and fatty acid catabolism -increases reactivity of the nervous systemby increasing sensitivity to epinephrine and norepinephrine -Control tissue growth and development along with hGH
Define molecules.
A group of atoms bonded together smallest fundamental unit of a chemical compound
Diabetes mellitus is related to blood sugar control not _______
ADH
Describe the thyroid gland
ANATOMICAL POSITION: -inferior to the larynx (voice box) -to locate think thyroid cartilage (adams apple) -lateral to the trachea STRUCTURE: -butterfly shaped -has 2 lateral lobes (left and right) -the bridge like connection between the two lobes lies anterior to the trachea and is called the isthmus -microscopic sacs called thyroid follicles make up most of the thyroid gland (these make up the largest portion of the glands mass)
What are the effects of hypersecretion disorders of human growth hormone from the anterior pituitary "during adulthood" ie; after a person is done growing?
Acromegaly After epipheseal plate closure, one ceases to grow linearly, but tissues don't cease to grow. As a result, bones can become thicker and denser and tissues of the eyelids, tongue nose, lips and skin can enlarge causing circulatory, nerve and skin problems. Enlargement and elongation of the bones of the face, jaw, cheeks and hands. The long bones of the extremities are unaffected because the growth plates are already closed. Commonly causes arthritis and carpal tunnel syndrome due to excess tissue growth.
Define permissive effect.
Action of one hormone requires the presence of another. So in other words, 2 different hormones must both be present for a desired reaction. EXAMPLE: epinephrine & thyroid hormone stimulating lipolysis
Describe the oxidation of iodine process
Before iodide can bind to tyrosine, it must be oxidized and combine with another iodide to form an iodine molecule (I2)
The most common cause of insufficient iodine is a ____________
goiter
Describe myxedema.
has similar symptoms to congenital hypothyroidism, without the CNS and skeletal abnormalities. By the time the person develops the disease the nervous system has developed and they are done growing. It is common for the patient to be mentally lethargic but not exhibit mental retardation. The abnormal edema in myxedema is related to deposition of excess connective tissue, resulting in the accumulation of water in the tissues. insufficient thyroxin during adulthood causes dry brittle hair, dry skin due to decreased prespiration, low BMR, temperature and hr. Gains weight easily.
When the osmotic pressure is high, the blood solute concentration is _________.
high
What are the signs and symptoms of hyperthyroidism?
high basal metabolic rate heat intolerant diarrhea increased respiratory rate high hr (tachycardia) weight loss anxious
A target cell can react more energetically if there is a high level of _________ or the cell has ___________ its receptors for the hormone.
hormone up-regulated
In some cases, __________ can interact with each other to get the desired effect.
hormones aka; permissive effect
The pituitary gland was formerly known as what...
hypophysis
The __________ _________ that produce the posterior pituitary hormones are the paraventricular and supraoptic nuclei.
hypothalamic nuclei The axons from these nuclei form the hypothalamohypophyseal tract. The tract ends near capillaries of the posterior pituitary. When stimulated, the hormones are released into the bloodstream.
the hormones of the posterior pituitary are synthesized in the ____________.
hypothalamus they are secreted down special neurosecretory neurons to be stored and later released from the posterior pituitary.
Myxedema is a ___________ disorder and occurs in __________
hypothyroidism adulthood
Congenital hypothyroidism In a ____________ disorder and occurs in ______________
hypothyroidism childhood
What is the reason for the thyroid hormone action "decreases blood cholesterol"?
ie; cholesterol reduces blood cholesterol by increasing cholesterol excretion
What is the reason for the thyroid hormone action "increases the effects of epinephrine and norepinephrine"?
ie; fight or flight enhances the sympathetic nervous response (heart rate, force of heart contraction and bp)
What is the reason for the thyroid hormone action "increase protein synthesis"?
ie; growth it encourages growth
What is the reason for the thyroid hormone action "accelerates body growth, especially during fetal life and adolescence"?
ie; growth work synergistically with human growth hormone and insulin to develop the skeletal and nervous system
What is the reason for the thyroid hormone action "increase the basal metabolic rate"?
ie; oxygen consumption The basal metabolic rate is the rate of oxygen consumption while awake, at rest and fasting. When the need for ATP increases, the use of all nutrients increases
What is the reason for the thyroid hormone action "stimulate the synthesis of additional sodium-potassium pumps"?
ie; regulating normal body temps This major action has a cascade of effects. With the increase in Na/K pumps, the demand for ATP is greater. As ATP is produced, calories are used and more heat is produced. This is how thyroid hormones help a person regulate their normal body temperature.
What is the reason for the thyroid hormone action "increases fatty acid and glucose catabolism"?
ie; synthesize ATP fatty acids and glucose are used to synthesize ATP
If the blood osmotic pressure rises, in an effort to maintain fluid equilibrium, the body will try to ___________ the reabsorption of water and __________ the amount lost in the urine. ADH plays a major role in this.
increase decrease
Define "up-regulation"
increased responsiveness by increasing receptor numbers EXAMPLE: Cancer cells up-regulate
The pituitary gland is anatomically and functionally connected to the hypothalamus by the _____________; a funnel shaped stalk.
infundibulum
Within the TGB molecule, one or two ________ atoms attach to each tyrosine molecule.
iodine
In many countries a goiter is due to __________ deficiency.
iodine The thyroid is making every effort to make thyroid hormone, but there isn't any iodine.
Define the term hormone.
is a "mediator molecule" secreted from one part of the body that circulates via the body fluids to cells in another part of the body. or in other words; they are mediator molecules that are released in one part of the body to influence activity somewhere else.
What does oxytocin do in men and non-pregnant women?
it is not clearly understood theories suggest it promotes feelings of sexual pleasure during and after intercourse and encourages emotional bonding between the mating pair. "love hormone".
Hormones are not present in _________ amounts but their effects are quite dramatic.
large
Which hormone type can "bind directly" to intracellular receptors?
lipid-soluble hormones because they can diffuse through the lipid bilayer of the target cell.
If the osmotic pressure is low, the concentration of solutes is _________.
low
The pituitary gland is commonly references as the __________ gland.
master
Describe Graves disease
most common form of HYPERthyroidism an autoimmune disease results in the production of antibodies that target TSH receptors. These antibodies act like TSH, so they stimulate thyroid hormone production. This is why the patient will demonstrate the symptoms of hyperthyroidism. A peculiar trait is called exophthalamos. This causes protrusion of the eyes. It is due to the abnormal fluid accumulation in the periorbital connective tissue and the extrinsic eye muscles nervousness, diminished body weight, diarrhea.
Describe water-soluble hormones.
must stimulate a cellular change by a more complex mechanism. they must bind to membrane receptors and initiate a change in the cell indirectly. As a result, this isn't a solubility classification it is also a "functional" classification.
Most hormones work by ___________ feedback, few by ___________ feedback.
negative positive
Molecules can be both _____________ and ___________; it just depends on how they are used.
neurotransmitters hormones
There are many types of kinases, so the effects can be...
numerous
In the hypothalamus there are ___________ that monitory blood osmotic pressure (concentration of solutes in the blood).
osmoreceptors
Diabetes means _________. Isipidus mean __________
overflow it relates to the development of polyuria (too much urine production) tasteless So putting these two terms together means the production of too much tasteless urine. Not the same as diabetes mellitus.
There is a scattered group of cells surrounding each follicle. What are these cells called?
parafollicular cells or C cells
What enzyme inactivates cAMP?
phosphodiesterase
Which gland is "pea shaped"?
pituitary gland
The endocrine system consists of what organs?
pituitary, thyroid, parathyroid, adrenal and pineal glands. Other organs and tissues that secrete hormones but they are not exclusively endocrine glands are; hypothalamus, thymus, pancreas, ovaries, testes, kidneys, stomach, liver, small intestine, skin, heart and placenta.
Hormone receptors are simply cellular ___________
proteins Like any other protein they can be synthesized, broken down and synthesized again.
The thyroid stores a 100 day supply of __________ products
secretory
Compare and contrast the control mechanisms of the nervous and endocrine systems; mediator molecules, site of mediator action, target cells, time to onset of action and duration. obj 2
see following slides
Describe the roles of negative and positive feedback in controlling hormones. obj 7
see following slides
List and describe the action of T3 and T4. obj 18
see following slides
Predict the effects and provide examples of hyper- and hyposecretion disorders of the thyroid hormones. obj 19
see following slides
Predict the effects and provide examples of hyper- and hyposecretion of antiduretic hormone (ADH). obj 15
see following slides
Compare the action of circulating versus local hormones, including the paracrines and autocrines. obj 4
see following slides SEE IMAGE on pg 629
Define goiter
simply an enlargement of the thyroid and it can be found in patients with hypothyroidism, hyperthyroidism and euthyroidism (normal thyroid function).
Describe lipid-soluble hormones.
small , neutrally charged or lipid soluble as a result it can diffuse into a cell and bind directly to intracellular receptors. These are carried in the blood via "transport proteins". Can freely diffuse through the cell membrane
The posterior lobe of the pituitary, also called the neurohypophysis, is functionally connected to the hypothalamus by what? TEACHER QUESTION
specialized neurosecretory neurons
_________ cells can dictate the number of receptors available to bind hormone.
target ie: up-regulation and down-regulation NOTE: If a cell wants to increase its responsiveness to a hormone, it can increase the number of receptors (up-regulation). If a cell wants to decrease its response to excessive hormone, the cell can decrease the number of receptors (down-regulation).
In the U.S. goiters are uncommon due to...
the fact that most of the available salt is "iodized"
What is the pituitaries "master" gland?
the hypothalamus NOTE: the hypothalamus is the connection between the nervous and endocrine system. It receives input from several regions in the brain; limbic, RAS, thalamus, etc.
The main functional unit of the thyroid is what? obj 17
the thyroid follicle Each follicle consists of an central, open space called the lumen, surrounded by a wall of cells called follicular cells. These cells change shape slightly from squamo--cuboidal to cuboido-columnar when stimulated to produce thyroid hormone.
To synthesize the thyroid hormones, TBG is released into the lumen of the ________ ___________.
thyroid follicles
Thyroglobulin (TGB) is a protein synthesized inside the _________ __________ ______.
thyroids follicular cells
ADH (antidiuretic hormone) is also called ____________.
vasopressin
_________ soluble hormones freely circulate in the bloodstream.
water
__________ soluble hormones can't pass through the cell membrane
water
ADH acts on three specific target tissues, what are they?
Kidneys: retain more water, which decreases urine output. sudoriferous (sweat) glands: decrease water loss by prespiration from the skin smooth muscle cells of blood vessels: arterioles constrict, which increases bp
________ soluble hormones are carried in the blood by transport proteins.
Lipid
__________ soluble hormones can freely pass through the cell membrane
Lipid
List the major chemical classes of hormones of the body.
Lipid-soluble hormones Water-soluble hormones NOTE: one of the main classifications separates different types of hormones based on their "solubility" in water or lipids. this is important to keep in mind when determining how the hormone will act on a target cell.
How is the thyroid stimulated?
Low T3 or T4 levels and a low metabolic rate stimulates the hypothalamus to secrete thyrotropin-releasing hormone (TRH), which results in the anterior pituitary producing thyroid-stimulating hormone (TSH). TSH binds to TSH receptors in the follicular cells and activates a number of processes required to synthesize T3 and T4.
What are signs and symptoms of hypothyroidism?
Low basal metabolic rate cold intolerant constipation decreased respiratory rate low hr (bradycardia) weight gain lethargic
Describe the posterior pituitary (neurohypophysis).
Consists of special axons and axon terminals from neurosecretory neurons. It doesn't synthesize any hormones. The hormones from the posterior pituitary are produces by neurosecretory cells within nuclei of the hypothalamus and secreted down the axons to be stored and later released from the posterior pituitary.
Define nephrogenic diabetes insipidus
Diminished renal response to the ADH that is produced or in other words, they don't respond to the ADH they make
What are the effects of hypersecretion disorders of human growth hormone from the anterior pituitary? Give examples.
EFFECTS: -has widespread effects on the body because the majority of cells have hGH receptors. The severity of the symptoms relates to the age of the patient. -hypersecretion of hGH during childhood will cause overall body portions to remain consistent but the patient will be very tall (GIANTISM). CAUSES: -excess hGH during person growth phase -main cause is tumor of the anterior pituitary EXAMPLES: -Giantism
What are the effects of hyposecretion disorders of human growth hormone from the anterior pituitary? Give examples.
EFFECTS: -has widespread effects on the body because the majority of cells have hGH receptors. The severity of the symptoms relates to the age of the patient. -hyposecretion of hGH during childhood will effect the epiphyseal plates. Without hGH, the epiphyseal plates will close before the child achieves a normal adult height. The deficient growth of tissue will affect all of the body systems; however, the child will have normal body proportions. CAUSES: -insufficient hGH release during an individuals growth phase. EXAMPLES: -Pituitary Dwarfism
Describe the general "functions" of the endocrine system.
FUNCTIONS: the endocrine system is made up of primary and secondary endocrine organs that, together with the nervous system, coordinate vital body functions in an effort to maintain homeostasis. They... -Control chemical composition and volume of the internal environment (blood) -Regulate metabolism and energy balance (thyroid) -Contraction of smooth and cardiac muscle fibers -Influence glandular secretions -Regulation of sleep-awake cycles (pineal) -Emergency control during physical and mental stress (trauma, starvation, hemorrhage, etc). -Integration of growth and development (thyroid) -Reproductive control -Some immune functions
Disorders of the endocrine system usually involve two main problems, what are they?
Having too much (hypersecretion) Having too little (hyposecretion) NOTE: there are other causes, but the symptoms will be similar to either hyper or hyposecretion. EXAMPLES: insufficient receptors, 2nd messenger defects, faulty receptors, etc.
___________ secretion is regulated by signals from the nervous system, chemical changes (fluctuations) in the blood and secretions (levels) of other hormones.
Hormone
_____________ can be delivered to cells throughout the body and bind to receptors in or on the target cell.
Hormones
Define tropic hormones
Hormones from the adenohypophysis that act on other endocrine glands. So in other words, if a hormone is a tropic hormone, it is release from one endocrine gland and targets another. The term "tropic" may also be used in the name of the specific cells that secrete it. EXAMPLES: thyro"trophs", cortico"trophs" and gonado"trophs" are all cells of the anterior pituitary that secrete a particular hormone that targets another gland.
Define inhibiting hormones
Hormones from the hypothalamus that inhibit the release of hormones from the adenohypophysis. So in other words, if the hypothalamus needs to suppress the action of the pituitary, it secretes specific inhibiting hormones. NOTE: Again this illustrates the negative-feedback response of the endocrine system.
Define releasing hormones.
Hormones from the hypothalamus that stimulate the "release" of hormones from the adenohypophysis. So in other words; to encourage the release of hormones from the pituitary, the hypothalamus secretes a number of "releasing hormones". NOTE: if "releasing" is in the name of the hormone, it comes from the hypothalamus.
Define circulating hormones.
Hormones secreted into the interstitial fluid and then into the bloodstream. NOTE: this gives them access to the entire body.
Define paracrines
Hormones secreted into the interstitial fluid that act on "neighboring" cells. NOTE: causing changes to nearby cells.
Define autocrines
Hormones secreted into the interstitial fluid that act on the same cell (self) that secreted it. NOTE: so they can stimulate themselves
Identify the source of the hormone Antidiuretic hormone (ADH) secreted by the neurohypophysis, its target organs and principal actions.
SOURCE: produced by the cell bodies of the neurosecretory cells in the hypothalamus (paraventricular nuclear cells and supraoptic nuclear cells) and are transported down the cells axons to the neurohypophysis. The hormones are then secreted in response to nerve impulses from the hypothalamus through the neurosecretory neurons. TARGET ORGANS: arterioles, collecting ducts in the kidney and sweat glands PRINCIPAL ACTIONS: causes arterioles to constrict thereby increasing bp, and targets the collecting ducts in the kidney and sweat glands in the skin to minimize water loss.
Identify the source of the hormone Oxytocin (OT) secreted by the neurohypophysis, its target organs and principal actions.
SOURCE: produced by the cell bodies of the neurosecretory cells in the hypothalamus (paraventricular nuclear cells and supraoptic nuclear cells) and are transported down the cells axons to the neurohypophysis. The hormones are then secreted in response to nerve impulses from the hypothalamus through the neurosecretory neurons. TARGET ORGANS: uterus and breasts PRINCIPAL ACTIONS: During and after the delivery of a baby. Through "positive feedback", oxytocin stimulates uterine contractions to help with the delivery of the infant. It also stimulates milk release ("let down") from the breasts in response to the sucking mechanism of the baby.
Identify the general structure of the thyroid follicle and describe the process of thyroid hormone (T3 and T4) synthesis, secretion, transport and control. obj 17 SEE IMAGES ON PG 648 (stimulating the thyroid gland and synthesizing thyroid hormone)
See above slide
Define the terms releasing hormones, inhibiting hormones and tropic hormones. obj 10
See following slides
Describe factors contributing to disorders of the endocrine system. obj 12
See following slides
Describe the anatomical and physiological relationships between the pituitary (which includes the adenohypophysis and the neurohypophysis) and the hypothalamus. obj 9
See following slides
Describe the anatomical location and general structure of the thyroid gland. obj 16
See following slides
Describe the processes that increase or decrease the number of receptors on the cell membrane. obj 3
See following slides
Identify the source of the hormones secreted by the neurohypophysis, their target organs and principal actions. obj 14 SEE IMAGE ON PG 644
See following slides
List the major chemical classes of hormones of the body and describe how each is carried in the blood. Obj 5
See following slides
List the seven hormones of the adenohypophysis, their target organs, their principial actions and the correlating releasing hormone from the hypothalamus. obj 11
See following slides
Predict the effects and provide examples of hyper- and hyposecretion disorders of human growth hormone (hGH) from the anterior pituitary. obj 13
See following slides
Relate the mechanism of hormone action to the biochemical nature of the hormone. obj 6
See following slides
Describe the factors that influence the responsiveness of a target cell to a hormone. obj 8
See following slides.
Give examples of lipid soluble hormones.
Steroid hormones: vit D, corticoids, estrogen, progesterone, androgens. Thyroid hormones: thyroxide (T4), tridothyronine (T3), thyroid stimulating hormone (TSH) Nitric Oxide: vasodilator
most body cells have receptors for ______ and _____ so the hormones actions are quite broad.
T3 T4
Describe the secretion of thyroid hormones process
T3 and T4 are lipid soluble, so they freely pass the cell membrane into the interstitial fluid and into the blood
Most of the synthesized thyroid hormone is ______, but ______ is more physiologically potent.
T4 T3 However, once secreted, most of the T4 is converted to T3 by enzymatic removal of an iodine.
Define Prolactin-releasing Hormone (PRH).
TARGET ORGANS: Mammary glands PRINCIPAL ACTIONS: Lactation of mammary glands CORRELATING RELEASING HORMONE: Prolactin (PRL)
Define Corticotropin releasing hormone (CRH)
TARGET ORGANS: Melanocytes PRINCIPAL ACTIONS: Darkens melanocytes CORRELATING RELEASING HORMONE: Melanocyte-stimulating Hormone (MSH)
Define Gonadotropic-releasing hormone. FOLLICLE
TARGET ORGANS: Ova/sperm PRINCIPAL ACTIONS: Ova/sperm development & production CORRELATING RELEASING HORMONE: Follicle Stimulating Hormone (FSH)
Define Gonadotropic-releasing hormone. LUTENIZING
TARGET ORGANS: Uterine lining, testosterone, overies PRINCIPAL ACTIONS: maturation of uterine lining, testosterone production and ovulation. CORRELATING RELEASING HORMONE: Lutenizing Hormone (LH)
Define growth hormone releasing hormone (GHRH).
TARGET ORGANS: all cells of body PRINCIPAL ACTIONS: stimulates growth of body cells CORRELATING RELEASING HORMONE: Human growth hormone (HGH)
Define Corticotropin releasing hormone (CRH)
TARGET ORGANS: cortex of adrenal gland PRINCIPAL ACTIONS: stimulates cortex of adrenal gland CORRELATING RELEASING HORMONE: Adrenocorticotropic Hormone (ACTH)
Define thyrotropin releasing hormone (TRH).
TARGET ORGANS: thyroid gland PRINCIPAL ACTIONS: stimulates thyroid gland CORRELATING RELEASING HORMONE: Thyroid Stimulating Hormone (TSH)
Describe the Synthesis of thyroglobulin (TGB) process
TGB is a glycoprotein produced by follicular cells. It contains large numbers of the amino acid tyrosine. Tyrosine is the site on the TGB molecule that will bind with iodine.
Define synergistic effect
The effect of two hormones acting together is greater than one acting alone. So in other words; if two hormones dictate similar actions and they work together to create an even more powerful result/stronger response.
Define positive feedback
The hormone output "encourages" and reinforces the stimulus EXAMPLE: hormone that helps with contractions and eventually the birth of a baby
Define negative feedback
The hormone output "reverses" a particular stimulus. EXAMPLE: Low blood sugar releases glucagon which poors out glucose into blood, thus increasing glucose levels in the blood.
Describe the anatomical relationship between the pituitary (including the adenohypophysis and the neurohypophysis) and the hypothalamus.
The hypothalamus is superior to the pituitary glands and is connected to the pituitary glands via the "infundibulum". In the pituitary glands the anterior pituitary ("adenohypophysis") is the biggest and in the pictures sits behind the posterior pituitary (neurohypophysis). Yeah doesn't make sense with the description.
TGB consists of 5000 ________ _________, >100 of which are the amino acid __________
amino acids tyrosine
A connective tissue _________ surrounds the layer of follicular cells.
basement
The action of water-soluble hormones is much more complex; why?
because of their limited lipid solubility, they can't freely enter the cell.
The anterior lobe of the pituitary, also called the adenohypophysis, is functionally connected to the hypothalamus by what? TEACHER QUESTION
blood vessels
ADH specifically influences the collecting tubules (ducts) in the kidneys to increase water reabsorption and limit the amount of water excreted as urine. As water reabsorption is increased, there is a resulting increase in the ________ _________ and thus the bp.
blood volume
What are the 2nd messengers used in the action of water-soluble hormones?
cAMP Ca++ (calcium ions) cGAMP (cyclic guanosine monophosphate)
ADH also increases the bp by ___________ the smooth muscle cells of arterioles.
constricting This is why it was called a vasopressin
Define "down-regulation"
decreased responsiveness by decreasing receptor numbers EXAMPLE: insulin resistant downgrade
ADH is a hormone that __________ the amount of urine the body produces.
decreases
the most common condition related to ADH is what?
diabetes insipidus
the study of endocrine glands and hormones is called...
endocrinology
Define congenital hypothyroidism
formally called cretinism ("idiot") in addition to the common symptoms of hypothyroidism the patient exhibits a low growth rate (dwarfism) and mental retardation, due to the synergistic relationship between the, thyroid hormones and human growth hormone. This decreases the development of the nervous and skeletal systems. insufficient thyroid hormone during growth
The anterior pituitary (adenohypophysis) physiologically is considered a __________ and the posterior pituitary (neurohypophysis) physiologically is considered a ___________.
gland neurosecretory neuron
Give examples of water soluble hormones.
Amines: catecholmines Peptides and proteins: ADH & oxytocin Eicosanoids: prostaglandins, leukotrienes
The pituitary has 2 lobes that are named based on their position and functional relationship to the hypothalamus. What are these names?
Anterior lobe of the pituitary (adenohypophysis): 75% of the total pituitary weight. Posterior lobe of the pituitary (neurohypophysis)
Describe the Coupling of T1 and T2 to make T3 and T4 process.
As one of the last steps, two tyrosine molecules are joined to form either T3 (T1 + T2) or T4 (T2 + T2).
Define the term target cell.
Initially hormones are secreted into the interstitial fluid, then typically the bloodstream, thereby having access to the entire body. A specific cell will respond to the hormone due to the presence of peripheral or intracellular receptors. Because these cells are the specific target hormones, they are referred to as "target cells".
Define Neurogenic diabetes insipidus.
Insufficient production or secretion of ADH or in other words don't secrete enough ADH With limited amounts of ADH, the patient will not reabsorb water, therefore they will secrete large volumes of very dilute urine and esssentially tasteless.
Describe the iodine trapping process.
Iodine circulates in the blood as iodide (I). Iodide is actively transported into the follicular cells. Because of this process, the thyroid gland contains most of the iodide in the body.
There are 2 physiological types of diabetes insipidus, what are they?
Neurogenic Nephrogenic Both have the same effect as the other
____________ are "released from neurons" to act locally in response to a nerve impulse.
Neurotransmitters NOTE: They bind to receptors in a postsynaptic membrane near their site of release.
Describe the transport of T3 and T4 in the blood process
Once in the blood stream, 99% of the secreted hormone binds to transport proteins, mainly thyroxine binding globulin (TBG), not to be confused with thyroglobulin (TGB)
Describe the pinocytosis and digestion of colloid process
Once synthesized, the iodine containing TGB reenters the follicular cells and digestive enzymes break down the molecule, releasing the formed T3 and T4
Define antagonisitic effect.
One hormone opposes the action of another. So in other words; because most hormones work as part of a negative feedback system, there are other hormones that oppose their actions. If one opposes the action of another, this is an antagonistic effect.
The prefex of each term in T4 thyroxin (tetraiodothyronine) and T3 triiodothyronine cells describes what?
The number of iodine molecules they contain. Tetra- meaning four Tri- meaning three
Describe the iodination of tyrosine process
The side chain of tyrosine may pick up on (T1) or two (T2) iodine molecules
What 2 hormones do the thyroid follicles secrete?
Thyroxine (tetraiodothyronine): T4 Triiodothyronine: T3
__________ molecules link to form thyroid hormone containing three or four atoms of iodine.
Tyrosine When needed, TGB moves into follicular cells, and digestive enzymes cleave T3 and T4 from the TGB molecule. T3 and T4 are lipid soluble, so they can diffuse through the plasma membrane and bind to the carrier protein thyroxin-binding globulin (TBG) in the blood.
Control mechanisms of the endocrine system include;
Uses Hormones Responses are usually distant from the site of release Targets: cells through the body Onset of action: SECONDS TO HOURS TO DAYS (slower reaction time than neurotransmitters) Action duration: GENERALLY LAST LONGER (duration longer)
Control mechanisms of the nervous system include;
Uses Neurotransmitters Local chemical release across a synapse Targets: muscle cells, glands and other neurons Onset of action: MILLISECONDS (act quickly) Action duration: MILLISECONDS (short duration) Effectors: glandular cells, various types of muscle cells and other neurons.
