Hypothalamo-hypophysial axis

Question 1

Functions of the endocrine system?

Answer 1

• growth and development
• sex differentiation
• metabolism
• adaption to an ever changing environment: regulation of digestion, use and storage of nutrients, electrolyte and water metabolism, and reproductive functions

Question 2

Where does magnocellular neurosecretory neurons have their effect?

Answer 2

• posterior lobe of the pituitary gland (on oxytocin and ADH)

Question 3

Where does the parvocellular neurosecretory neurons have their effect?

Answer 3

• on anterior lobe of the pituitary gland

Question 4

Autonomic nerves have effects on what target organs?

Answer 4

• pancreas (has both pre and post ganglionic autonomic neuron) and adrenal gland (just preganglionic autonomic neuron)

Question 5

What do hormones function as?

Answer 5

• move through the blood/lymph to distant target sites of action (these are endocrine and neuroendocrine cells)
• can also act more locally as paracrine or autocrine (have effect on themselves (like a T cell) messengers that incite more local effects
• most are present in body fluids at all time in greater or lesser amounts as needed
• signal amplification

Question 6

Characteristics of hormones?

Answer 6

• a single hormone can exert various (pleiotropic) effects in different tissues
• a single function can be regulated by several hormones (ex: HR)

Question 7

How do water soluble hormones effect cells?

Answer 7

• needs a receptor on cell membrane -> first messenger binds to receptor and this activates G protein , effector cell and second messenger and target cell response in the cell

Question 8

How do fat soluble hormones effect cells?

Answer 8

These can pass right through cell membrane and bind to receptor, now it is able to go into nucleus and have impact on cell

Question 9

What are the factors that affect the response of a target cell to a hormone?

Answer 9

• blood level of the hormone
• relative number of receptors: up-regulation, down regulation
• affinity of these receptors for hormones: affected by number of conditions, ex: pH of body fluids plays an important role in the affinity of insulin receptors

Question 10

Describe up and down regulation of the receptors?

Answer 10

up regulation: number of receptors on the cell wall are increased so this means that there are more areas for the hormones to attach so more hormones are secreted resulting in a greater response
down regulation- ex: sympathetic system stimulates heart for prolonged periods -> leads to tachycardia and to reduce tachycardia, the receptor sites on teh cell are reduced, and there are less receptors for hormones to attach to. Beta blockers decrease the number of sites available on the cell surface, being selective and increasing output

Question 11

Humoral response of parathyroid glands to low concentration of Ca2+

Answer 11

• capillary blood contains low concentration of Ca this stimulate secretion of parathyroid hormone (PTH) by parathyroid glands

Question 12

Neural effect on medulla of adrenal gland?

Answer 12

• preganglionic SNS finber stimulates adrenal medulla cells to secrete catecholamines

Question 13

Hormonal effect on hypothalamus and target organs?

Answer 13

• the hypothalamus secretes hormones that stimulate the anterior pituitary gland to secrete hormones that stimulate other endocrine glands to secrete hormones (thyroid, adrenal cortex and gonads)

Question 14

How are hormone levels controlled?

Answer 14

• affected by fluctuations that vary with the sleep-wake cycle: GH and ACTH
• secreted in a complicated cyclic manner: femal sex hormones
• regulated by feedback mechanisms that monitor substances such as glucose (insulin) and water (ADH) in the body
• regulated by feedback mechanisms that involve the hypothalamic pituitary target cell system

Question 15

When do glucocorticoid levels peak?

Answer 15

after you wake up in the morning, between 8 and 9 am (maybe why MIs occur more in the morning)

Question 16

What has an effect on estrogen levels?

Answer 16

• LH and FSH, when they peak -> estrogen levels rise

Question 17

Categories of hormones according to structure?

Answer 17

• biogenic amines
• amino acids, peptides, polypeptides, proteins, and glycoproteins
• steroids
• fatty acid derivatives

Question 18

Hormones that the hypothalamus secretes?

Answer 18

• TRH, GnRH, CRH, GHRH, somatostatin

Question 19

Hormones that the anterior pituitary secrete?

Answer 19

• ACTH, TSH, FSH, LH, PRL, GH

Question 20

Hormones that the posterior pituitary secrete?

Answer 20

• oxytocin and ADH

Question 21

Hormone that the thyroid secrete?

Answer 21

• calcitonin

Question 22

Hormones that the pancreas secretes?

Answer 22

glucagon, insulin, somatostatin

Question 23

Hormone that the kidney secretes?

Answer 23

renin

Question 24

Hormone that the heart secretes?

Answer 24

ANP

Question 25

Hormones that the GI tract secretes?

Answer 25

gastrin, CCK, secretin, GIP, somatostatin, GLP-1

Question 26

Hormone that adipocytes secrete?

Answer 26

leptin

Question 27

What are the 2 groups of hormones that are derived from the amino acid tyrosine?

Answer 27

- thyroid hormones are basically a double tyrosine with critical incorporation of 3 or 4 iodine atoms - catecholamines include epi and NE, which are used as both hormones and neurotransmitters (act on vasculature)

Question 28

Process from preproinsulin to insulin

Answer 28

- preproinsulin -> signal sequence is cleaved off --> proinsulin --> chain c cleaved off -> insulin (chain A and B), now active

Question 29

Leptin makes you feel?

Answer 29

- full, pts that are obese have decreased sensitivity to leptin

Question 30

What is the hunger hormone?

Answer 30

ghrelin

Question 31

What hormones are made in zona fasciculata of adrenal gland cortex?

Answer 31

cortisol and corticosterone

Question 32

What hormone is made in the zona glomerulosa?

Answer 32

aldosterone

Question 33

What hormones are made in the zona reticularis?

Answer 33

androgens

Question 34

Why is the pituitary gland so heavily vascularized?

Answer 34

-to allow for rapid access of blood to pituitary and rapid release of hormones

Question 35

5 cell types of the anterior pituitary gland?

Answer 35

- thyrotrophs: produce thyrotropin, also called TSH - corticotrophs: prouce corticotrophin, also called ACTH - Gonadotrophs: produce gonadotropins -> LH and FSH - somatotrophs: produce GH - lactotrophs: produce prolactin (production of milk)

Question 36

How does the negative feedback loop work?

Answer 36

- endocrine cell releases hormones -> target cell -> this illicit a physiologic response and since there is an increase in hormone levels it stops the endocrine cell from secreting anymore hormones and this results in decrease in hormone levels

Question 37

How does the positive feedback loop work?

Answer 37

endocrine cells releases hormones so increase in levels -> target cell and ilicts a physiologic response and it tells the endocrine cell to keep on secreting hormones even though levels are increasing (positive feedback with continued hormone production)

Question 38

Where does glucocorticoids provide negative feedback?

Answer 38

- to hypothalamus (stop producing CRH) and to the anterior pituitary gland (stop producing ACTH)

Question 39

What stimulates the production of cortisol?

Answer 39

stress does stress -> stimulate hypothalamus to produce CRF -> this stimulates anterior pituitary to produce ACTH and this stimulates adrenal glands to produce cortisol and when enough is produced it will decrease stress inhibit hypothalamus and pituitary glands from producing hormones.

Question 40

Production of LH and FSH?

Answer 40

- hypothalamus produces GnRH which stimulates anterior pituitary to produce LH and FSH and this will have effect on gonads (testes) -> LH produces testosterone and rising levels of testosterone will inhibit anterior pituitary production of LH and hypothalamus, FSH produces inhibin in testes this will inhibit anterior pituitary production of FSH

Question 41

Parturition feedback loop?

Answer 41

postive feedback loop PG (prostaglandins) -> uterine contractions -> positive feedback -> increased stretch -> more uterine contractions Oxytocin -> uterine contractions -> positive feedback loop -> more oxytocin Ocytocin -> positive feedback to PG -> uterine contractions ->contractions until baby is delivered

Question 42

Regulation of parturition?

Answer 42

- increased CRH (placental) -> ACTH (fetal) -> DHEA (fetal) -> E3 -> oxytocin, PG and gapp juntions of uterine muscle -> all increase uterin contractions