lecture 6: Metablism 4 (endocrine system 1)

Question 1

what’s the primary aim of the endocrine system?

Answer 1

to maintain a stable and balanced internal environment (homeostasis)

Question 2

what’s the difference between the nervous and endocrine system in terms of responses

Answer 2

NS releases fast acting neurotransmitters, while the endocrine system releases slower acting hormones into the bloodstream and interstitial fluid

Question 3

what do exocrine glands do? what are the exocrine glands?

Answer 3

secrete products (not hormones) into ducts and are expelled outside of the body
sudoriferous (sweat) glands
sebaceous (oil) glands
mucous glands
digestive glands

Question 4

exocrine hormones do not secrete ____?

Answer 4

hormones!!!

Question 5

what’s the overall method of both endo and NS?

Answer 5

to have signals
neurotransmitters in the NS
hormones in the endocrine system

Question 6

how do hormones/neurotransmitters initiate a response?

Answer 6

they bind to receptors on target cells

Question 7

how does signaling by hormones differ from signaling by neurotransmitters?

Answer 7

hormones circulate around but target specific cells
- receptor shape is specific to the hormone
NT act on cells (in and around)

Question 8

where do hormones bind?

Answer 8

they target specific organs/tissues where they bind to specific protein receptor cells which are molecules embedded in the membrane or cytoplasm of cell

Question 9

what do the activated cells do

Answer 9

they develop and act in certain ways based on the signal transmitted by the hormone

Question 10

what do hormones determine?

Answer 10

• the development if sexual characteristics in puberty
• regulate how the body grows and develops
• how the body controls fluid, salt and sugar levels in the body

Question 11

if men and women have both estrogen and testosterone, then what determines the secondary sex characteristics?

Answer 11

the level of these hormones
- depends on the amount of receptors that accept the release

Question 12

what are the three main pathways hormones have for action

Answer 12

travel in blood and act on distant target cells (circulation hormones; endocrines)
act on neighbouring cells (paracrines)
act on the same cell that secreted them (autocrines)

Question 13

what is a good example of autcrocrines?

Answer 13

the immune system:
- needs local regulation to bring WBC (cell to cell communication)

Question 14

what are the lipid soluble hormones? What is their role?

Answer 14

steroid, and thyroid hormones, nitric oxide
- circulate bound to transport portines
- diffuse across the plasma membrane
- bind to receptors within target cells
- activate genes to allow ribosomes to synthesize specific proteins

Question 15

what are the water soluble hormones, what do they do?

Answer 15

cannot pass thru the membrane so they bind to receptors on the membrane:
amine hormones, peptide and protein hormones, eicosanoid hormones)
- circulate freely in the plasma
- activate a secondary messenger to phosphorylate cellular proteins

Question 16

what does it mean to phosphorylate

Answer 16

turn receptors “on” or “off”
- activates (excitatory)
- inactivates (inhibitory)

Question 17

what happens when a receptor is activated?

Answer 17

it results in the production of proteins through a chain reaction

Question 18

how can hormone regulation be controlled

Answer 18

through alterations to the receptors themselves

Question 19

how can receptors be up-regulated/down-regulated? what does this mean

Answer 19

up-regulated - become more sensitive in the presence of low concentrations of hormone (more receptors)
down-regulated - become less sensitive in the presence of high concentrations of hormone

Question 20

why would we want receptors to be upregulated/down-regulated?

Answer 20

tissues get different levels of hormone because this allows them to have a more invidiulaistc regulation
- we want one tissue to be up-regulated and another to be down-regulated

Question 21

the response of a target cell to a
hormone is based on…

Answer 21

• hormone/s [] in the blood
• the # of hormone receptors on the target cell
• and influences exerted by other hormones

Question 22

how would a hormone exert its influence on another hormone?

Answer 22

synergistic effect
antagonistic effect

Question 23

t/f hormones are released all at once

Answer 23

f they’re released in short bursts, to prevent over/underproduction of the hormone

Question 24

how is hormone secretion regulated?

Answer 24

• chemical changes in the blood
• signals from the nervous system
• other hormones
  the ES relies on feedback systems to recluse hormone production/secretion

Question 25

mist endocrine glands are under which feedback control? what does this allow

Answer 25

negative. prevents deviation from a set point in the body

Question 26

positive feedback mechanisms control?

Answer 26

self-perpetuating events - release of stimulus builds upon itself so you need an external break to stop the pathway

Question 27

positive feedback encourages a response ___ the body’s set point

Answer 27

away from

Question 28

positive feed back are much less common. what is an example of them?

Answer 28

release of oxytocin during childbirth

Question 29

what is one of the most important functions of the hypothal. what are its most important roles

Answer 29

to link the nervous and endocrin systems controls homeostasis for body temp, blood glucose levels and osmotic pressure

Question 31

how many hormones are leased by the hypo. what do they basically do

Answer 31

TRH, CRH, GnRH, PRH, GHRH (aka. *somatocrinin*) they drive the ES by telling the pituitary glans which hormones to release

Question 32

why do we have releasing hormones? couldn’t the hypo. just directly secrete hormones to the target organs/tissues?

Answer 32

hormones are separated from systemic circulation; they are controlled by the release into the pituitary gland without immediate dilution into the bloodstream - similar to the blood brain barrier, the brain is protected from hormonal fluctuations that could disrupt its function

Question 33

hormones released from the hypothalamus can also be inhibiting hormones. what are examples of inhibiting hormones? what does they do?

Answer 33

GHIH (*somatostatin*), and PIH (*dopamine*) tells pit. not to release hormones

Question 34

The hypothalamus and pituitary gland are connected by the ____. how do hormones reach the pit.

Answer 34

infundibulum (stalk) via the hypophyseal portal system

Question 35

ant. pit. aka ____, makes up —-7. of the weight of pit. how many cells are within it and how many hormones does it release

Answer 35

adenohypophysis 75% 5 types of cells and they secrete seven hormones

Question 36

what are the ant. pit. hormones and what are they secreted by?

Answer 36

hGh secreted by somatotrophs PRL secreted by lactotrophs TSH secreted by thyotrophs FSH & LH secreted by gonadotrophs ACTH & MSH secreted by corticotrophs

Question 37

what’s the most plentiful hormone released by ant. pit.? what does it do? what is it controlled by?

Answer 37

hGh; aids in growth of muscles and bones controlled by 2 hyp. hormones: - GHRH - GHIH

Question 38

if one was giving Gh what parts of the body will grow bigger out of proportion?

Answer 38

nose and ears cuz they’re made of cartilage not bone

Question 39

what’s the role of TSH? what’s it controlled by? what abt prolactin?

Answer 39

stimulates the production of thyroid hormones from the th gland and is controlled by TRH PRL with other hormones initiates and maintains milk secretion by the mammary glands

Question 40

role of FSH & LH

Answer 40

in females FSH initiates follicle development and secretion of estrogens in the ovaries in males, FSH stimulates sperm production in the testes **LH in females** stimulates the secretion of estrogens by ovarian cells to result in ovulation and stimulates formation of the corpus luteum and secretion of progesterone **in males**, stimulates interstitial cells of testes to secrete testosterone

Question 41

roles of acth

Answer 41

controls the production and secretion of glucocorticoids by context of adrenal gland

Question 42

what is the posterior lobe, aka ___, made of? what does it do?

Answer 42

neurohypophsyis made of neural tissue does not release any hormones, but stores: - OT, and ADH

Question 43

what is the role of oxytocin? when is it released

Answer 43

released in response to stretch placed on the cervix during childbirth - it enhances contractions of mother’s uterus - stimulates milk production by the mammary glands in response to suckling - in males, aids in the dopamine-OT-NO pathway for erections

Question 44

the amount of ADH secreted varies with ___ ____? what are its roles

Answer 44

osmotic pressure ADH decreases urine output as part of a negative fb loop where osmoreceptors in the hypothalamus monitor blood OP

Question 45

and incr./decr. in bv does what to ADH

Answer 45

incr = in bv causes a decr in ADH secretion decr in bv cause an increase in ADH secretion

Question 46

what is the relationship between alcohol and ADH

Answer 46

alcohol inhibits adh - acts on the hormone not the kidneys causing you to produce more urine