Topic 12: Endocrine System I

Question 1

What does hormone mean?

Answer 1

Greek for “to excite”

Question 2

What are hormones and what do hormones help do?

Answer 2

chemical signaling molecules responsible for regulation

messenger of endocrine system -> allows cells to communicate with each other

Question 3

How do hormones work?

Answer 3

secreted in body fluids, usually blood
binds to target cells
all cells are exposed, only those with correct receptor respond

Question 4

What are receptors and what do they do?

Answer 4

large proteins or glycoproteins on surface of target cells
recognize and bind to specific hormones
responsible for specificity of endocrine system
continually synthesized and degraded

Question 5

What occurs if hormone levels are too high? What if they are too low?

Answer 5

down-regulation

up-regulation

Question 6

How does endocrine signaling work?

Answer 6

endocrine cells secrete hormones into extracellular fluid
diffuse into bloodstream -> travel across body
attach to receptors on target cells

Question 7

Explain short distance signaling

Answer 7

cells produce and secrete LOCAL regulators

reach target cells by diffusion (not through bloodstream)

Question 8

What are the 5 types of short distance signaling?

Answer 8

paracrine signaling
autocrine signaling
synaptic signaling
neuroendocrine signaling 
signaling by pheromones

Question 9

Define paracrine signaling

Answer 9

target cells NEAR secreting cels

Question 10

Define autocrine signaling

Answer 10

target cells ARE secreting cells

Question 11

Define synaptic signaling

Answer 11

neurons form synapses with target cells

neurotransmitters are involved

Question 12

What are neurotransmitters?

Answer 12

signaling molecules are produced by neurons, diffuse across synapse and bind to receptors on target cells

Question 13

Define neuroendocrine signaling

Answer 13

neurosecretory cells secrete neurohormones which diffuse into bloodstream

Question 14

What happens in signaling by pheromones?

Answer 14

chemicals released into external environment
target other individuals of same species to:
define territory
warn of predators
attract mates

Question 15

What are the two classes of local regulators?

Answer 15

modified fatty acids: contain long hydrocarbon chains

gases: diffuses to surrounding muscle, activates enzymes, relaxes cells, vasodilation, more blood to tissue

Question 16

Which are hydrophilic and hydrophobic? Polypeptides, steriods, amines

Answer 16

hydrophilic - polypeptides and amines

hydrophobic - steroids and amines

Question 17

What does water-soluble hormones do? What does lipid-soluble hormones do?

Answer 17

water-soluble affects proteins in cytoplasm of target cells - acts faster, but short-term effects
lipid-soluble affects gene expression of target cells - acts slower, but last longer

Question 18

What does water-soluble hormones involve? Define it

Answer 18

signal transduction: series of changes in cellular proteins that convert extracellular chemical signals into specific intracellular responses

Question 19

SEQ water-soluble hormone pathway

Answer 19

CANNOT pass through membranes

1. hormone secreted via exocytosis
2. travels freely in bloodstream
3. binds receptor on target cell membrane (often G-protein-coupled receptor)
4. G protein binds and activated adenylyl cyclase
5. adenylyl cyclase converts ATP to cyclic AMP (cAMP) - 2nd messanger
6. cAMP activated protein kinase (enzyme)
7. other proteins inhibited or activated -> response

Question 20

SEQ lipid-soluble hormone pathway

Answer 20

CAN pass through membranes

1. diffuses across endocrine cell membrane
2. binds transport protein - soluble in blood
3. diffuses across cell membrane into target cells
4. binds receptor in cytoplasm
   - > hormone receptor complex enters nucleus
5. H-RC binds DNA
   - > change in gene expression
   
   • > response

Question 21

Do hormones have only one type of effect?

Answer 21

Many have more than one type of effect

Question 22

What does epinephrine do?

Answer 22

its a rapid response by body in emergencies
triggers glycogen breakdown in liver
increases blood flow in skeletal muscle
decreases blood flow in smooth muscle
can be due to different receptors or different intracellular proteins

Question 23

What does the endocrine do? Characteristics of endocrine?

Answer 23

release hormones into surrounding fluid -> bloodstream
ductless
can be isolated cells or part of organs
functions with nervous system to regulate metabolism, maintain homeostasis

Question 24

What does the exocrine do? Example?

Answer 24

release materials into ducts
carry secreted substances to target area
examples: sweat, mucus, digestive enzymes