Auburn Choi Exam 3: Endocrine

endocrine glands job

synthesize and secrete molecules called hormones that communicate with and control other body cells

how they release hormones

1. hormones are released from endocrine gland cells into the interstitial fluid directly, which then enter the blood

2. hormones are transported within the blood by the cardiovascular system to all body tissues

3. they randomly leave the blood from the capillaries and enter the interstitial fluid, which provides the hormone molecules access to body cells

4. the hormone binds to its target cell's receptor, which can initiate or inhibit metabolic activity

What is one of the general functions of the endocrine system?

Regulating development, growth, and metabolism

What is a function of the endocrine system related to blood?

Maintaining homeostasis of blood composition and volume

What does the endocrine system control in relation to food?

Controlling digestive processes

What reproductive function does the endocrine system control?

Controlling reproductive activities

secretory cells are organized in 2 ways

- a single organ with only an endocrine function

- cells housed in small clusters within organs or tissues that have other primary functions

endocrine gland

refers to either an endocrine organ or an organ/tissue with endocrine cells

endocrine reflex

regulated secretion of a hormone from an endocrine gland

how is an endocrine reflex initiated

a. hormonal stimulation

b. humoral stimulation

c. nervous system stimulation

hormonal stimulation

release of a hormone in response to another hormone

humoral stimulation

changes in level of nutrient or ion in the blood triggers release of hormone

nervous system stimulation

stimulation by the nervous system triggers release of the hormone

categories of hormones

a. endocrine hormones

b. paracrine hormones

c. circulating hormones

endocrine hormones

transported within the blood

paracrine hormones

short-lived molecules that influence cells within the local tissue from which they are produced

circulating hormones

grouped according to their chemical structure

1. steroids

2. biogenic amines

3. proteins

synthesized within endocrine cells from either

a. cholesterol

b. amino acids

What are local hormones?

Large group of short-lived signaling molecules that do not circulate within the blood.

What is autocrine stimulation?

When a hormone binds to the same cell that produces it.

What is paracrine stimulation?

When a hormone binds to neighboring cells.

how do lipid-soluble hormones travel in the blood

they require a carrier protein because they do not dissolve in the aqueous environment of plasma

role of carrier protein

act as a "boat" for the hormone and protect it from early destruction

binding between lipid-soluble hormone and carrier protein

temporary and the hormone can "hop around" between carrier proteins

bound hormone

hormone that is attached to a carrier protein

unbound hormone

hormone that is not attached to a carrier protein

water-soluble hormones

do not need carrier proteins because they readily dissolve in blood

2 main factors that influence hormone concentration

hormone release and hormone elimination

what increases hormone concentration in the blood

hormone release from an endocrine gland

what decreases hormone concentration in the blood

elimination through enzymatic degradation, excretion in urine, or uptake by target cells

water-soluble hormones half life

short, few minutes to an hour

why do lipid-soluble hormones have longer half lives

they are protected by carrier proteins and don't need to be produced as often

lipid-soluble hormones

small, nonpolar, lipophilic

lipid-soluble hormones bind where?

intracellular receptors after entering the cell

water-soluble hormones

polar and unable to cross the plasma membrane

how do water soluble hormones stimulate target cells

by binding to membrane receptors and triggering a signal transduction pathway

what is the first messenger in a water-soluble hormone pathway

the hormone itself

what is the second messenger

molecule formed inside the cell that modifies cellular activity

2 types of signal transduction pathways

1. adenylate cyclase

2. phospholipase C activity

lipid-soluble ease of access to blood and cells

harder to get into blood, easier to enter cells

water soluble ease of access to blood and cells

easier to get into blood, harder to enter cells

what must hormones bind to in order to affect a target cell

receptors

up regulation

increase in number of receptors in response to low hormone concentration

down regulation

decrease in the number of receptors in response to high hormone concentration

3 types of hormone interactions

1. synergistic

2. permissive

3. antagonistic

synergistic interaction

- one hormone reinforces the activity of another

- "working together"

permissive interaction

- one hormone needs another to function

- "gives permission"

antagonistic interaction

one hormone opposes the effect of another

what does the posterior pituitary do

stores hormones (ADH and oxytocin) made by the hypothalamus

why are hypothalamic neurons called neurosecretory cells

they produce hormones that are stored and released from the posterior pituitary

what does ADH (antidiuretic hormone) do

- kidneys: reduce urine output

- thirst center: triggers thirst

what does oxytocin do in females

stimulates uterine contractions during labor and milk ejection during breastfeeding

what does oxytocin do in males

aids sperm movement through reproductive ducts

what are additional effects of oxytocin

- improves mood

- lowers stress

- reduces blood pressure

- increases pain tolerance

- released during physical affection

what is oxytocin known as

love hormone

what types of hormones does the hypothalamus release

releasing hormones (RHs) and inhibiting hormones (IHs)

what do RHs do

stimulate the anterior pituitary to release hormones

what do IHs do

inhibit the release of hormones from the anterior pituitary

how many RHs and IHs are there

5 RHs and 2 IHs

6 major hormones released by the anterior pituitary

1. thyroid-stimulating hormone

2. prolactin

3. follicle-stimulating hormone

4. luteinizing hormone

5. adrenocorticotropic hormone

6. growth hormone

what do follicular cells produce

thyroid hormone

what do parafollicular cells produce

calcitonin (helps lower blood calcium levels)

what triggers thyroid hormone release

hypothalamus releases TRH-> anterior pituitary releases TSH-> thyroid gland releases TH

what does TH do

acts on target cells to regulate metabolism

what tissues make up the adrenal glands

medulla: nervous tissue

cortex: endocrine tissue

what does the adrenal medulla release

catecholamines (epinephrine and norepinephrine) to prolong the fight-or-flight response

three zones of the adrenal cortex

1. zona glomerulosa

2. zona fasciculata

3. zona reticularis

zona glomerulosa: what does it produce

mineralocorticoids

ex: aldosterone

what does aldosterone do

regulates Na and K by promoting Na and water retention and K excretion in urine

zona fasciculata: what does it produce

glucocorticoids

ex: cortisol

zona reticularis: what does it produce

gonadocorticoids

ex: sex hormones; androgens

what triggers cortisol release

low cortisol, stress, or time of day-> hypothalamus releases CRH-> anterior pituitary releases ACTH-> adrenal cortex releases cortisol

pancreatic islets

where endocrine cells are found in the pancreas

what do alpha cells secrete

glucagon

what do beta cells secrete

insulin

what do delta cells secrete

somatostatin (growth hormone- inhibiting hormone)

what do F cells secrete

pancreatic polypeptide

what happens when blood glucose increases

beta cells detect it-> release insulin-> target cells respond-> blood glucose decreases

what happens when blood glucose decreases

alpha cells detect it-> release glucagon-> raise blood glucose levels

what does leptin do

satiety hormone-signals brain to feel full

what does ghrelin do

hunger hormone- released when stomach is empty