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A&P review Q&A mod. 2
Terms in this set (31)
How do hormones exert their actions?
By interacting with high-affinity receptors
Which class of hormones usually circulates in the blood unbound to transport proteins?
Protein & peptide hormones
With cell surface receptors, the binding of a hormone activates the __________, which in turn, acts on an effector, such as ____________, to create the second messenger_________________.
G-protein, adenyl cyclase, cAMP
What is the difference between up-regulation & down-regulation?
Up-regulation - occurs in response to a decreased level of hormone. This causes an increase in the amt of receptors on a cell for that particular hormone. The presence of more receptors makes the cell more sensitive to that hormone
Down-regulation - occurs in response to an increased level of hormone. This causes a decrease in the amt of receptors on a cell for that particular hormone. The presence of fewer receptors makes the cell less sensitive to that hormone.
What 2 types of hormones have intracellular receptors?
Thyroid and steroid hormones
List the 5 types of cells in the anterior pituitary, hormones they produce, and their functions.
• Thyrotrophs - TSH; stimulates thyroid gland to produce T3 & T4
• Corticotrophs - ACTH; stimulates release of steroids from adrenal cortex (Zona fasciculata)
• Gonadotrophs - FSH: females - promotes follicle development in ovaries and production of estrogen
FSH: males - stimulates spermatogenesis in Sertoli cells in seminiferous tubules (think FSH = Spermatogenesis & Sertoli cells)
LH: females: induces ovulation, stimulates secretion of estrogen and progesterone
LH: males - promotes production of testosterone from Leydig cells (think LH = Leydig cells)
• Somatotropes - GH; necessary for growth and metabolic process, i.e.: increase in growth of almost all tissues in body (effect on bones and muscle, is primarily through somatomedins, which are produced by liver. GH stimulates their production and release from liver)and metabolic effects, such as increase in protein synthesis, increased lipolysis for fat for energy, gluconeogenesis and decrease in glucose use by body, (can result in hyperglycemia)
• Lactotrophs - Prolactin - Stimulates development of mammary glands, as well as the mammary glands to produce milk
Fun Fact! How much of the anterior pituitary must be destroyed before hypopituitarism becomes clinically evident?
List the growth-promoting and anti-insulin effects of GH
• Increased protein synthesis (stimulate uptake of amino acids from blood and synthesis of proteins) which leads to increase in size and function of organs, and increased lean muscle mass; increase in cartilage, linear bone growth.
• Increased lipolysis and use of free fatty acids for energy, which causes decrease in adipose tissue.
• Increased gluconeogenesis in liver. Decrease in use of glucose for energy, which leads to increase in blood glucose.
Many of GH's actions are indirectly mediated by what substance? What organ produces this substance?
Somatomedins (also known as Insulin-like growth factors - IGFs). Produced by liver
List the steps in the formation of thyroid hormone.
Thyroglobulin synthesized in follicular cells and stored in colloid and Iodide ions are absorbed through digestive tract and transported to thyroid gland → Carrier proteins transport iodide ions (iodide trapping) into cytoplasm of follicle cells → Iodide ions are converted to activated iodine by thyroid enzyme peroxidase and attached to tyrosine portion of thyroglobulin molecule in colloid → Oxidation of tyrosine continues (first forming T1 monoiodothyronine and T2 diiodothyronine) until T3 (triiodothyronine) & T4 (thyroxine) are formed → Thyroglobulin (containing T4 & T3) released from colloid cavity into follicle cells → Lysosomal enzymes break down thyroglobulin → Amino acids,T3 & T4 enter cytoplasm → Amino acids recycled & used to synthesize more thyroglobulin and T3 & T4 diffuse into capillaries & enter bloodstream → Majority of T3 & T4 entering bloodstream attach to thyroxin-binding globulins and other plasma proteins → Remaining unbound hormones diffuse into peripheral tissues gradually
What are the hormone producing cells in the adrenal medulla?
What are some of the effects of catecholamines?
"fight or flight" response:
- Increases oxygen consumption & carbon dioxide production
- Increases metabolic rate
- Increases respiratory rate
- Cardiac stimulation (increase HR and BP)
- Dilates bronchi & bronchioles
- Causes hyperglycemia
- Increased sweating
- Pupillary dilation
What are the differences between epinephrine and norepinephrine?
Both cause almost the same effects in the body except:
Epi - greater cardiac stimulation, also makes up approx. 80% of catecholamines
Norepinephrine - greater effect on vasoconstriction & BP, also makes up approx. 20% of catecholamines
What are the 3 layers of the adrenal cortex? What is produced in each?
Glomerulosa - mineralcorticoids
Fasciculata - glucocorticoids
Reticularis - sex hormones
T or F: Hormones from the adrenal cortex are metabolized by the liver.
TRUE. A patient with liver disease has a decreased ability to deactivate hormones produced by the adrenal cortex
Describe the renin-angiotensin mechanism.
The liver produces angiotensinogen. The kidney produces the enzyme renin (the juxtaglomerular apparatus becomes excited when there is a decrease in blood volume, BP, or blood concentration) and the renin cleaves protein from angiotensinogen to create angiotensin I. ACE (angiotensin converting enzyme) from the lungs converts angiotensin I into angiotensin II. Angiotensin II stimulates the release of aldosterone.
What are the effects of angiotensin II?
• Increase in reabsorption of Na, Cl, and water from kidneys, increased K excretion
• Vasoconstriction and increase in BP
• Increased secretion of ADH (and, therefore, increased water reabsorption
• Increased SNS activity
What are the effects of aldosterone?
• Excretion of potassium
• Increase in sodium retention (and, thereby, water retention)
Reabsorption of sodium, chloride, bicarb, and water
What does an ACE-I (angiotensin converting enzyme inhibitor) prevent from forming? What about an ARB (angiotensin II receptor blocker)?
ACE-I prevents the formation of angiotensin II (and, thereby, aldosterone)
ARB's prevents angiotensin II from stimulating the release of aldosterone
List the ways that cortisol affects the various aspects of metabolism?
- Affects carbohydrate metabolism
o Stimulates gluconeogenesis (fatty acids and amino acids used for gluconeogenesis)
o Decrease in glucose utilization by most cells in body
o Increase in insulin, but a decrease in the sensitivity to insulin
- Increases protein and fat metabolism
o Promotes mobilization fatty acids from adipose tissue
o Shifts primary energy source to fatty acids
o Decrease in protein stores in body, except in liver (proteins used for rebuilding and enzymes)
What are cortisol's effects on inflammation?
- Stabilizes lysosomal membranes
- Decreases permeability of capillaries
- Decreases migration of WBC's into inflamed area
- Suppresses immune system
- Attenuates fever
What are the two types of main cells in the pancreas, what do they secrete, and where do they secrete in to?
• Acini cells - digestive juices into the duodenum
• Islets of Langerhans - insulin and glucagon directly into the blood
List the types of cells that make up the Islets of Langerhans and what they each secrete.
• Alpha cells - Synthesize & secrete glucagon
• Beta cells - Synthesize & secrete insulin & amylin
• Delta cells - Synthesize & secrete somatostatin
• PP Cells - Synthesize & secrete pancreatic polypeptide
What is the function of glucagon, and what stimulates its release? Inhibits?
Function - helps to maintain blood glucose levels between meals and when fasting.
• low blood sugar (causes gluconeogenesis, promotes glycogenolysis, stimulates breakdown of triglycerides to use fatty acids for energy)
• increase in amino acids (promotes uptake by liver and conversion of amino acids into glucose
• Exercise - to prevent hypoglycemia
Diabetes Mellitus Type I is most commonly caused by destruction of what cells in the pancreas?
What are counter-regulatory hormones and which hormones are classified as such?
Other hormones that maintain or increase blood glucose levels (work counter to insulin, which lowers BG)
Examples: catecholamines, GH, and glucocorticoids
What is glycolated hemoglobin (HgA1C) and why do we test it in DM?
- Evaluates hemoglobin in which glucose has been incorporated. This is essentially irreversible, so it provides a picture of a patient's BG control over 6-12 weeks.
How do sulfonylureas work in the control of BG? What must a patient have in order for this class of drugs to work?
They stimulate the beta cells in the pancreas to release more insulin
Pt must have some residual beta cell function.
Describe how biguinides function and what some of the benefits are of these drugs
• Inhibit production of glucose from the liver and they increase the sensitivity of peripheral cells to insulin.
• Does not cause hypoglycemia as a side effect (because it does not stimulate the release of insulin). Also can cause weight loss and improved lipid profiles.
What is the benefit of α-Glucosidase Inhibitors and how do they function?
They delay the absorption of carbohydrates from the gut, thereby helping to prevent postprandial hyperglycemia.
What is the only class of medications that directly target insulin resistance and where do they work?
TZD's. They increase insulin sensitivity in the liver, fat, and skeletal muscle
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