Lec 06

Question 1

Cell can adjust their sensitivity to hormone

Answer 1

Adjust sensitivity of receptor (min/hour FASTER)
Adjust number of receptors (days/week)

Question 2

Up-regulation

Answer 2

Try to maintain response despite low hormone conc.
Increase number of receptors in response to sustained low hormone conc.

Question 3

Down-regulation

Answer 3

Decrease receptor number in response to sustained high hormone conc.
Usually Endocytosis of membrane receptors

Question 4

Up/down regulation are long-term effects

Answer 4

Time required for endo/exocytosis, proteins synthesis

Question 5

Faster changes may be achieved by ——

Answer 5

Sensitization—desensitization
Modification of existing receptors to change their activity
**total number of receptors does not change

Question 6

Tropic hormones

Answer 6

-Many neurohormone of the hypothalamus
-hormone of the anterior pituitary
— target another endocrine gland to control hormone release

Question 7

Synergism

Answer 7

Influence of multiple hormones
— there is functional overlap of hormones
— combination of any chemical signal

Question 8

Permissiveness

Answer 8

B is permissive for A if:
— if hormone A can’t produce its full effect without the presence of hormone B
-B does not need to have same effect like A

Question 9

Hormones as functional antagonists

Answer 9

-opposite action
-insulin vs glucagon
-don’t need to share receptors or signaling pathways

Question 10

Insulin cycle

Answer 10

1-STIMULUS: Blood glucose level rises 2- Pancreas betta cells produce insulin
3- liver takes up glucose and store as glycogen
3- body cells takes up more glucose
4- Blood glucose level declines
5-homeostasis

Question 11

Glucagon cycle

Answer 11

1-STIMULUS: Blood glucose level decreases
2- Pancreas alpha cells produce glucagon
3- liver breaks down glycogen and release into blood
4- Blood glucose level rises
5-homeostasis

Question 12

Ligand

Answer 12

Chemical molecule that bind to the receptor
**Primary ligand usually

Question 13

Agonist

Answer 13

Ligand that binds to a receptor and enhances its activity

Question 14

Antagonist

Answer 14

Ligand binds to a receptor and inhibits its activity

Question 15

Target cell response determined by receptor and intracellular signal pathways not the ligand

Answer 15

Agonist for this receptor can be antagonist for the other

Question 16

Specificity

Answer 16

Receptors may show preference for particular ligand
-very specific—bind very few ligands
-non-specific—bind many different ligands(not at same time)
**ligands can have specificity for receptor as well

Question 17

Competition

Answer 17

Multiple ligand may compete for same receptor
-usually one has higher affinity
-overall effect of each ligand decrease compared if they were the only one

Question 18

Competitive antagonist

Answer 18

Same binding site on receptor as agonist
—can be overcome by increasing agonist conc.

Question 19

Non-competitive antagonist

Answer 19

Different binding site on receptor(allosteric site)
-or same active site but cannot unbind (irreversible antagonist)
-cannot overcome by increasing agonist concentration

Question 20

Dose-response curve

Answer 20

%response depends on agonist conc.
-increases with %of receptors bound to agonist
-if agonist conc. Is high enough, receptor will be saturated and response is maximal

Question 21

EC50

Answer 21

Agonist concentration producing 50% of the max response

Question 22

Competitive antagonist and dose-response curve

Answer 22

Make it mire difficult for agonist to bind
-max response can still be achieved with increasing agonist concentration

**EC50 INCREASES BY ANTAGONIST CONCENTRATION INCREASE

Question 23

Non-competitive antagonist and dose-response curve

Answer 23

Change availability of binding site or irreversibly block it

**DECREASE IN MAX POSSIBLE RESPONSE BY INCREASE IN ANTAGONIST CONCENTRATIONS