Chapter 16 Endocrine System: Both Lectures

Question 1

Define half-life in relation to circulating hormones.

Answer 1

amount of time to eliminate 50% of the hormone, depends on hormone’s structure and solubility

Question 2

Compare and contrast the hormonal and neural controls of body functioning.

Answer 2

nervous - fast effects, short-duration responses b/c body clears them out quickly, APs and NTs, specific locations, short distance

endocrine - slow effects, long-duration responses, hormones, diffuse locations, long-distance

both - alter gene expression to regulate activity of cells somehow, i.e. Epinephrine and NE from adrenal medulla

Question 3

Define onset in relation to circulating hormones.

Answer 3

how long it takes for a hormone to have an effect; affected by its solubility

Question 4

Describe, in detail, the cyclic AMP second messenger system used by water-soluble hormones to exert effects on target tissues.

Answer 4

hormone doesn’t enter cell, stays on receptor until released, transmembrane receptor proteins have confirmational shape change → hormone molecule plus receptor = GPCR → receptor activates G protein, it kicks off molecule of GDP → opens binding site for GTP, G protein travels → activates other G proteins (amplifies effect) → finds target enzyme and activates it (called adenylate cyclase) → enzyme converts ATP to 2nd messenger called cAMP → cAMP’s concentration changes → acts as messenger to activate lots of protein kinases → phosphorylate target proteins → change activity of molecules like activate more enzymes, dump contents (degranulate), exocytosis, open ion channels to adjust RMP/plasma permeability

at every level of the process, the signals are amplified

one hormone can change a lot of metabolism inside cell

Question 5

Identify three factors that influence a hormone’s effect on its target cell and explain the role of each.

Answer 5

blood level of hormone, number of receptors, affinity between receptor and hormone

amount of hormone can influence number of receptors

Question 6

what does exocrine duct do?

Answer 6

ducts release the exocrine gland’s secretions into external environment (skin, mucous membrane)

Question 7

Explain how up-regulation and down-regulation of hormone receptors and target tissues affects the activity of the hormone.

Answer 7

up-regulation is response to low hormone levels, means cells make more surface receptors

down-regulation is response to high hormone levels, means cells desensitize self by removing receptors - causes cell not to be as affected by hormone

Question 8

List and locate the body’s major endocrine organs.

Answer 8

pituitary, pineal (melatonin), thyroid, adrenal glands, thymus (some endocrine tissue, secretes thymocin)

Question 9

What determines whether a particular cell is able to respond to a given hormone?

Answer 9

the presence of a specific hormone receptor

Question 10

tropic hormone

Answer 10

hormone that stimulates release of another hormone, usually released from anterior pituitary gland

Question 11

three major types of stimuli that trigger hormone release from endocrine glands?

Answer 11

neural, hormonal, humoral

Question 12

Differentiate water-soluble hormones and lipid-soluble hormones.

Answer 12

water-soluble: all amino acid-based hormones except thyroid hormones, packaged into secretory vesicles and released via exocytosis, make way to bloodstream, find target cells w/surface receptors (extracellular),

lipid-soluble: all steroid hormones plus thyroid hormones, use transport proteins to travel through bloodstream, diffuse through PM so don’t need surface receptors

both: effect gene expression (division, making proteins)

Question 13

Which hormone type can diffuse across PMs?

Answer 13

steroid hormones, lipid-soluble (receptors are inside cytosol)

Question 14

Describe, in detail, the PIP2-calcium second messenger systems used by water-soluble hormones to exert effects on target tissues.

Answer 14

hormone → surface receptor → activate G protein → G protein moves around → activates more → find target enzyme → enzyme binds PIP2 → cut into two 2nd messenger molecules called DAG and IP3 → DAG stays in PM and travels there, IP3 acts as second messenger in cytosol → open calcium channels on ER to allow Ca2+ into cytosol → lots of effects including exocytosis of other hormones, activate different enzymes, and more cellular responses

2 names because 2 second messengers (PIP2 & Calcium)

Question 15

classic example of down regulation

Answer 15

insulin resistance that leads to diabetes type II

Question 16

Define duration in relation to circulating hormones.

Answer 16

how long hormone’s action lasts; ranges from 10 seconds to many hours,

Question 17

GPCR

Answer 17

hormone molecule plus receptor = GPCR

G-PROTEIN COUPLED RECEPTOR

Question 18

Explain the regulation of hormone release (three stimuli).

Answer 18

negative feedback loops - target cells’ effects feed back on original gland to decrease

1 humoral - stimuli = changing levels of ions in blood, simplest type, i.e. parathyroid gland cells monitor Ca2+ and release PTH as needed

2 neural - stimuli = nerve fibers, classic example is response to stress: SNS stim. adrenal medulla to release NE and E

3 hormonal - stimuli = hormone release caused by another hormone (tropic hormone), i.e. hypothalamic-pituitary-target endocrine organ feedback loop

Question 19

Water-soluble hormones affect target cells by binding to

Answer 19

plasma membrane receptors

Question 20

classic example of neural stimulus

Answer 20

APs in preganglionic sympathetic fibers to adrenal medulla leads to adrenal medulla cells releasing E and NE

Question 21

Differentiate hormones, paracrines, and autocrines.

Answer 21

hormones - systemically released and acts at any tissues that have the corresponding receptor and responses can have longer-term effects

paracrines - released locally into interstitial fluid and travel to neighboring cells

autocrines - released locally into IF and travel to self

lots of overlap between autocrines and paracrines because molecules can bind to self and also neighboring cells

Question 22

All amino-acid-based hormones except ___ use a second messenger system to alter a target cell’s gene expression and metabolism.

Answer 22

thyroid hormones

Question 23

SG: Which of the following is NOT a steroid hormone?

m. Testosterone
n. Cortisol
o. Gonadotropin Releasing Hormone
p. Aldosterone

Answer 23

gonadotropin releasing hormone

Question 24

exocrine gland examples

Answer 24

salivary glands, pancreas, lacrimal, mammary, digestive glands

Question 25

list water-soluble hormones

Answer 25

glycoproteins, catecholamines, TSH, FSH, luteinizing hormone, insulin

Question 26

list fat-soluble hormones

Answer 26

all steroids plus thyroid hormone, sex hormones including estrogen, progesterone, testosterone; cortisol, aldosterone

Question 27

classic example of hormonal stimulus

Answer 27

hormones from hypothalamus stimulate anterior pituitary gland to secrete hormones that stimulate other endocrine glands (thyroid gland, adrenal cortex, testis) to secrete hormones

Question 28

classic example of humoral stimulus

Answer 28

low concentration of Ca2+ in capillary blood leads to parathyroid glands secreting PTH which increases blood Ca2+

Question 29

SG: Which of the following has both endocrine and exocrine function?

i. Pineal Gland
j. Thyroid Gland
k. Adrenal Medulla
l. Pancreas

Answer 29

pancreas

Question 30

Differentiate amino-acid-based hormones and steroid hormones.

Answer 30

amino-acid-based hormones - protein hormones, can’t diffuse through PM,

steroid hormones - synthesized from cholesterol (fat), diffuse through plasma membrane

both - circulate systemically, access to lots of cells but only act on target cells

Question 31

Differentiate endocrine glands and exocrine glands (including ducts)

Answer 31

exocrine have duct to release secretions into external environment;
endocrine have no ducts, release hormones into blood plasma instead

Question 32

SG: Which of the following is a neuroendocrine organ?

e. Adrenal Cortex
f. Thyroid Gland
g. Gonads
h. Hypothalamus

Answer 32

hypothalamus

Question 33

Describe the general mechanism used by lipid-soluble hormones to exert effects on target tissues.

Answer 33

don’t need surface receptors → binds to receptor inside cell and forms complex b/w self and receptor → complex goes into nucleus → alters expression in DNA to make new proteins or silence genes → change activity of cell

Question 34

list organs that have partial endocrine function

Answer 34

pancreas (pancreatic islets-glucagon, insulin), gonads (ovaries/testes) produce hormones, placenta (hormones), adipose tissue (leptin), stomach (gastrin), intestine (CCK & secretin), kidneys (EPO), heart (ANP)