1. The Endocrine System

Question 1

What are endocrine and exocrine glands?

Answer 1

endocrine glands –> these are ductless glands that secrete hormones into the blood.
exocrine glands –> these secrete products through ducts (e.g. pancreatic duct for pancreatic enzymes)

Question 2

What is autocrine activity?

Answer 2

when the secreting cells hormone acts on itself in someway.

Question 3

peptide vs steroid hormones

1. structure
2. synthesis
3. storage
4. interaction in blood vessels
5. mode of action
6. time for effect to occur.

Answer 3

1. peptide = hydrophilic (amino acid derived = small, polypeptide = large). steroid = hydrophobic, small
2. peptide hormones made by the rough ER. Steroids made by the smooth ER
3. peptides stored in vesicles and released upon signal. steroids not stored since they can diffuse out of the cell (they are made when needed)
4. peptide dissolve in plasma, steroids associate with proteins (albumin)
5. peptides bind surface receptors and act through second-messenger cascades. steroids diffuse into the cell and directly bind cytoplasmic receptors
6. peptides modify enzyme activity and thus its quick (hours). steroids alter gene expression and thus its long (days).

Question 4

What kind of hormone is synthesized by the rough ER?

Answer 4

rough ER = peptide hormones

smooth ER = steroids

Question 5

What are tropic hormones? Give an example.

Answer 5

Tropic hormones are hormones that regulate other hormones. Hormones released from the hypothalamus are typically tropic hormones
For example, CRH is released by the hypothalamus which causes the release of ACTH by the AP which stimulates release of cortisol by the adrenal cortex.

Question 6

t or f, cortisol negatively regulates both the hypothalamus and the anterior pituitary.

Answer 6

True, as cortisol levels rise, they will feed back and stop CRH and ACTH

Question 7

What is the hypothalamic-pituitary portal system?

Answer 7

The hypothalamic-pituitary portal system is an isolated circulatory system that allows hypothalamic excititory and inhibitory releasing factors direct contact with the anterior pituitary gland.

Question 8

t or f, blood vessels will only lead to one capillary bed before returning to the heart

Answer 8

This is generally true since pressure drops significantly in capillary beds. However, in portal systems, two capillary beds exist so there can be direct communication between sites.

Question 9

If the hypothalamus communicates with the AP via the portal system, how does the PP receive signals?

Answer 9

the posterior pituitary receives signals via hypothalamic axons that release hormones. The posterior pituitary is essentially an extension of the hypothalamus.

This is why the posterior pituitary is also called the neurohypophysis.
the anterior pituitary is called the adenohypophysis.

Question 10

t or f, ALL hypothalamic and pituitary hormones are peptide hormones.

Answer 10

true
only steroid hormones we deal with are sex hormones, cortisol, and some water balance hormones (adrenal cortex essentially).

Question 11

Explain the 5 hypothalamus hormones (releasing factors) and the 6 anterior pituitary gland hormones that they release, briefly.

Answer 11

hypothalamus –> AP –> effector gland –> effect

1. GnRH –> LH –> stimulates sex hormone production in gonads (testosterone and estrogen)
2. GnRH –> FSH –> stimulates production of gametes (eggs and sperm)
3. TRH –> TSH –> thyroid gland releases thyroid hormone –> regulates basal metabolism and increase body temperature
4. PRH / PIH –> Prolactin –> mammary glands –> promotes milk production
5. GHRH / GHIH –> Growth hormone –> produces insulin-like growth factor, stimulates body growth
6. CRH –> ACTH –> adrenal cortex –> cortisol –> regulates stress response, activates glycogen stores.

Question 12

What kind of hormone is thyroid hormone?

Answer 12

thyroid hormone is a peptide hormone

Question 13

What two hormones come from the posterior pituitary and what are their roles?

Answer 13

1. anti-diuretic hormone (ADH): controls water retention in the kidneys
2. oxytocin: controls milk release and uterus contractions during parturition. This is a positive feedback loop hormone.

Question 14

The thyroid gland produces thyroid hormone and what other hormone (from thyroid c-cells)?

Answer 14

thyroid c-cells produce calcitonin which is responsible for controlling (lowering) calcium serum levels

Question 15

What hormone does the parathyroid produce?

Answer 15

parathyroid hormone (PTH) –> this increases serum calcium levels (which opposes calcitonin)

Question 16

Explain the hormones of the adrenal medulla (1) AND adrenal cortex (n=3).

Answer 16

Adrenal medulla produces epinephrine (adrenaline). EN is responsible for sympathetic nervous system responses like increased HR.
Adrenal cortex produces three hormones, all steroids
1. cortisol: manages stress and metabolism
2. aldosterone: increases sodium reabsorption (increases BP)
2. sex steroids (capable of this but not as important)

Question 17

the pancreas also has endocrine functions (islets of Langerhans): What 3 hormones are produced here and from what cells?

Answer 17

1. Beta cells –> insulin –> lower blood glucose levels (increase glycogen anabolism)
2. Alpha cells –> glucagon –> increase blood glucose levels (increase glycogen catabolism)
3. delta cells –> somatostatin inhibits digestive processes

Question 18

What hormones do the ovaries and testes produce?

Answer 18

ovaries

1. estrogen: female characteristics
2. progesterone: pregnancy
   testes: testosterone: male characteristics and spermatogenesis

Question 19

What hormone does the heart release?

Answer 19

Atrial-natriuretic factor (ANF) which increases urination and decreases BP

Question 20

What hormone does the kidney release?

Answer 20

The kidney releases erythropoietin which increases RBC synthesis.

Question 21

What 5 hormones are steroids (the rest are peptide or amino acid derivative (EN))

Answer 21

adrenal cortex hormones (cortisol and aldosterone) as-well as all sex steroid (E, P, and T).

Question 22

What is the thymus? What hormone does it release?

Answer 22

The thymus makes T cells (located above the heart). In children the thymus releases thymosin which helps with T cell development