Olson, Cell Physiology

Front 1

Where are different receptors located?

Back 1

- In or on the surface of the cell membrane
- In the cytoplasm
- In the nucleus

Front 2

True or False:
Receptor proteins are often inactivated or destroyed; they may also be reactivated or manufactured.

Back 2

True

Front 3

What is the concept of Down-Regulation?

Back 3

A decrease in receptor proteins because of high concentrations of ligands.
- inactivation of receptor molecules
- temporary sequestering of molecules
- destruction of molecules
- decreased production

Front 4

What is the concept of Up-Regulation?

Back 4

The stimulation of increased formation of receptors or a greater availabiltiy of receptors for interaction.

Front 5

What is the end result of either Up regulation or Down regulation?

Back 5

Up = greater drug effect
Down = less effect b/c harder for drug to find receptor.

Front 6

With Denervation injury up-regulation occurs. How would you adjust your dose of Sux?

Back 6

You would increase your dose. Sux is an agonist. It would take more sux to occupy the increased # of receptors.
- be careful will have increased K+ release too

Front 7

What is the end result of either Up regulation or Down regulation?

Back 7

Up = greater drug effect
Down = less effect b/c harder for drug to find receptor.

Front 8

How would you adjust your dosing of NDMRs with denervation injury (up regulation)?

Back 8

Give less drug. NDMRs are antagonists. It is easier for the NDMRs to find receptors b/c there are more of them.

Front 9

Why shouldn't you stop a beta-blocker acutely? Explain in terms of up regulation/down regulation.

Back 9

It can cause rebound HTN. WIth beta-blockers the adrenergic receptors are blocked from the effects of norepi and epi. The body perceives that there is not enough norepi or epi so it makes more receptors (up regulation). Because when you stop the BB you have a ton of receptors that are now available for norepi and epi causing a increased BP.

Front 10

Given an example of when Down regulation occurs.

Back 10

With high dose, chronic opioid use. Because there is lots of drug available it causes the receptors to decrease thus causing the body to require more and more drugs to find and stimulate the receptors.

Front 11

What is the Meyer-Overton Theory?

Back 11

- It showd a correlation b/w anesthetic potency and lipid solubility.
- It hypothesizes that anesthesia occurs after a sufficient number of anesthtic molecules (critical volume) are dissolved in critical hydrophobic sites (lipid soluble membranes).

Front 12

What is the theory that states that anesthesia occurs after a sufficient number of anesthetic molecules are dissolved in crucial hydrophobic sites such as bilipid cell membranes.

Back 12

Meyer-Overton Theory

Front 13

True or False:
Lipid solubility is indirectly proportional to potency.

Back 13

False, directly proportional

Front 14

True or False:
No common chemical structure for compounds that produce anesthesia exists.

Back 14

True

Front 15

How does a decreased body temperature affect anesthetic requirements?

Back 15

Decreases requirement

Front 16

How do anesthetics affect the CNS?

Back 16

Anesthetics interfere with formation, release, or breakdown of neurotransmitters in the CNS.

Front 17

What hypothesis suggests that protein receptors in the CNS are the site for mechanism of action of inhaled anesthetics.

Back 17

Protein Receptor Hypothesis.
- It is supported by the steep dose-response curve for volatiles

Front 18

List several functions of Proteins.

Back 18

- Act as transport channels for ions & electrolytes
- Act as specific carriers for amino acids and sugars
- Act as enzymes that drive active pumps
- Act as receptors for substances moving in & out of cell
- Act as cell surface markers that identify cells to others
- Act as adhesion molecules that allow cells to attach to each other and to cytoskeleton

Front 19

What are the two main functions of receptors on the target cell?

Back 19

- To recognize and bind to their particular hormone
- To initiate a signal to intracellular effectors

Front 20

What are the functions of Signaling receptors?

Back 20

- Physically transfers signal from receptor to target w/in cell
- Amplify signal received
- Distribute signal for divergence to several targets
- Can be modulated by interfering factors

Front 21

What are three classifications of membrane receptors?

Back 21

- Ligand-gated ion channels (Channel Linked)
- Enzyme-linked (catalytic) receptors
- G-protein linked receptors

Front 22

True or False:
Changes produced from anesthetics occur within seconds and must be reversible.

Back 22

True

Front 23

Describe Ligand-gated Ion Channel Receptors.

Back 23

- Provide rapid signaling b/w electrically excitable cells.
- They are involved in fast synaptic transmission.
- These channels open and close in response to neurotransmitters changin ion permeability of plasma membrane of the post-synaptic cell.
- ex. GABA, Nicotinic ACh

Front 24

Describe Enzyme-linked receptors.

Back 24

- Activated by ligands and function directly as enzyme
- Linked to intracellular domain that binds and activates kinases w/in cell when receptor is occupied.
- Produces slowed response
- Ex. Insulin, growth hormones

Front 25

Describe G-protein linked receptors.

Back 25

- Indirectly activates or inactivates the membrane enzyme or ion channel.
- The interaction is mediated by guanosine triphosphate (GTP) - binding regluatory protein (G-protein)
- Has 3 parts: alpha, beta, gamma
- When the receptor is occupied alpha subunit becomes free and activates enyzme or ion channel.
- Fast response
- Ex. Muscarinic ACh

Front 26

What are the two binding sites for G-protein linked receptors?

Back 26

- on cell surface
- in cleft b/w segments within membrane

Front 27

What are first messengers?

Back 27

The extracellular chemical messengers are considered the first messenger (ligand)
- They regulate opening or closing of channel or gate in the membrane.
- Opening occurs because of conformational change in protein that blocks or opens the channel.

Front 28

Binding of the first messenger with a membrane receptor causes what?

Back 28

- Opening or closing of specific channels in membrane to regulate movement of ions in or out
- Activation of receptor that triggers activity within the cell
- Transfer of signal to intracellular messenger or second messenger that triggers cascade of biochemical events within the cell.

Front 29

What are Second messengers?

Back 29

Some ligands can't enter the tartet cell to bring about a response throught the first messenger.
- The major second messenger systems Adenylate cyclase/cAMP and Phospholipase C/inositol phosphate (IP3) system
- The 2nd messengers cause a coupling with G-proteins and activation of the alpha subunit
- cAMP activates a cascade of enzymes that trigger reactions that lead to cell's response to a ligand.
- IP3 activates membrane bound kinase C regulating Ca++ release

Front 30

How do Beta-2 agonsits work?

Back 30

Activates adenylate cyclase causing the conversion of ATP to cAMP. This causes bronchodilation and relaxation of smooth muscles

Front 31

Increased cAMP in cardiac muscles causes what?

Back 31

Higher Ca++ influx and positive inotropic effects

Front 32

Extracellular chemical messengers binding to receptors are:
1. first messenger
2. second messenger
3. ligand messenger

Back 32

1 and 3 (first and ligand)

Front 33

First messengers:
1. arent important in transmission of 2nd messenger
2. regulate opening & closing of channel
3. always block the channel

Back 33

2. reulate opening and closing of channel