General Physiology

Question 1

Describe the difference between endocrine hormones, paracrines, autocrines, and cytokines

Answer 1

Endocrine hormones - released into circulation to act on target organ somewhere else
Paracrines - released hormones to act on neighboring cells
Autocrines - act on same cells
Cytokines - can act as paracrines, autocrines or circulating hormones

Question 2

What are the 3 classes of proteins?

Answer 2

• peptides and proteins
• steroid hormones (cortisol, aldosterone)
• tyrosine hormones (thyroid hormones, epinephrine/norepi)

Question 3

What is the difference between polypeptides and proteins?

Answer 3

Both made of AAs, polypeptides up to 100 AA, >100 are proteins

Question 4

Describe the production/synthesis of polypeptides and protein hormones

Answer 4

Produced by the endoplasmic reticulum—> Golgi apparatus to be placed into vesicles —> vesicles either released by exocytosis to release hormones or stored under cell surface for later release

Question 5

Describe the synthesis of steroid hormones. How are these stored?

Answer 5

Synthesized from cholesterol
very little storage of steroids –> but store cholesterol –> can be used for synthesis fast

fat soluble

Question 6

In what two places/organs are hormones derived from tyrosine produced?

Answer 6

• thyroid gland
• adrenal medulla

Question 7

What is thyroglobulin?

Answer 7

macromolecule that is used to bind and store thyroid hormones in the thyroid gland

Question 8

What plasma protein carries thyroid hormones?

Answer 8

thyroxine-binding globulin

Question 9

What is the normal ratio of epinephrine to norepinephrine secretion from the adrenal medulla?

Answer 9

4 to 1

Question 10

Name 2 water-soluble hormones

Answer 10

adrenaline
growth hormone

groups: catecholamines and peptides are water soluble

dissolve in plasma and freely “swim” to target tissue

Question 11

Name 2 protein-bound hormone types

Answer 11

thyroid hormones, steroids

need to be protein-boudn to be transported to target tissues –> once at target tissues need to dissociate from the protein to become active and move into tissue

Question 12

What are 4 ways of metabolic clearance of plasma hormones?

Answer 12

• hepatic excretion into bile
• renal clearance
• metabolism by tissues
• binding with tissues

Question 13

How are steroid hormones mainly cleared?

Answer 13

conjugated into the bile by the liver

liver failure –> excessive plasma steroid hormone levels

Question 14

How are catecholamines and peptide hormones cleared?

Answer 14

degraded by tissue enzymes and then excreted by liver and kidneys

Question 15

Where are receptors located for:
* catecholamines and peptides, proteins
* steroid hormones
* thyroid hormones

Answer 15

catecholamines/peptides - cell membrane
steroid hormones - cytoplasm
thyroid hormones - nucleus

Question 16

What enzyme catalyzes the formation of cAMP

Answer 16

adenylyl cyclase

Question 17

Explain the function of calmodulin in smooth muscle cells

Answer 17

receptor for Ca (similar to troponin C in skeletal and cardiac muscles) –> when calcium binds –> calmodulin will activate myosin light chain kinase –> activtes muscle contraction

Question 18

Explain the steps by which aldosterone promotes Na reabsorption

Answer 18

• moves into the renal tubular cells
• binds to cytoplasmic receptor (mineralocorticoid receptor)
• indcues production of surface proteins that promote sodium reabsorption

Question 19

what are different words for the adenohypophysis and the neurohypophysis

Answer 19

anterior pituitary gland
posterior pituitary gland

Question 20

What part of the pituitary gland are TSH, ACTH, and GH secreted and released from?

Answer 20

anterior pituitary gland

Question 21

What part of the pituitary gland is ADH released from?

Answer 21

posterior pituitary gland

Question 22

Explain how the signals from the hypothalamus differ to the anterior versus posterior pituitary

Answer 22

hypothalamus sends signals to the anterior pituitary gland via hormones (GnRH, TRH, CRH, etc.) that move via the hypothalamic-pituitary capillary network (hypothalamic-hypophysal portal vessels) to stimulate production of hormones in the anterior pituitary

hypothalamus and posterior pituitary are connected as long cells originating in the hypothalamus and their axons reaching down and forming the posterior pituitary

Question 23

What are the 4 main effects of growth hormone

Answer 23

• tissue growth
• protein synthesis
• fat mobilization
• decreased rate of glucose utilization

Question 24

What proteins does GH utilize to mediate some of its effects?

Answer 24

insulin-like growth factors

Question 25

What are the 2 triggers for ADH release and where are these triggers sensed?

Answer 25

increased osmolality --> hypothalamus, osmoreceptors decreased effective circulatory volume --> stretch receptors in the atria, baroreceptors in the carotid, aortic, and pulmonary regions

Question 26

Explain how ADH increases water absorption

Answer 26

ADH binds to membrane receptors (V2 receptor) --> triggers activation of adenylyl cyclase --> more cAMP in the tubular cytoplasm --> phosphorylation of vescicles which then insert themselves into the cell membrane --> aquaporin-2