Cell Receptor & Signal Transduction

Question 1

What type of receptors are incorporated into the phospholipid cell membrane? They can be integrated with a number of intracellular proteins, enzymes, 2nd messengers and protein kinases

Answer 1

Membrane-bound receptors

Question 2

Intracellular receptors are found in what 2 places?

Answer 2

Cytoplasm or nucleus

Question 3

Signal transduction usually involves a _______ of events

Answer 3

A cascade of events

Question 4

What is the fastest acting of all of the receptor mechanisms?

Answer 4

A membrane bound receptor that opens an ion channel

Question 5

What is a drug that opens up Cl- channels?

Answer 5

Propofol

Question 6

What type of receptor does propofol bind to?

Answer 6

GABA

Question 7

A membrane bound receptor with signal transduction can be coupled with an enzyme and second messenger inside the cell to bring about a cell response.

These enzymes are what type of proteins?

Answer 7

Peripheral proteins

Question 8

What is the first thing to happen after a ligand binds to a membrane bound receptor coupled with an enzyme and second messenger inside the cell? (What enzyme is activated)

Answer 8

Guanylate cyclase is activated

Question 9

What does the activated enzyme guanylate cyclase do to GTP?

Answer 9

Converts GTP to cyclic GMP (cGMP)

Question 10

What does cGMP activate that brings about the cellular response?

Answer 10

Protein kinase G

Question 11

What type of enzyme can inactivate second messengers, such as cGMP, causing cGMP to break down to GMP and cease of cell response?

Answer 11

Phosphodiasterases

Question 12

Guanylate cyclase is no longer activated when?

Answer 12

When the ligand is removed from the receptor site

Question 13

A G-protein is coupled with a membrane bound receptor and is composed of what 3 subunits?

Answer 13

Alpha, beta, and gamma subunit

Question 14

Which subunit is attached to GDP?

Answer 14

Alpha subunit

Question 15

What happens to the G protein/alpha subunit when a chemical signal binds to the receptor

Answer 15

It separates from the receptor, GTP replaces GDP on the alpha subunit and it separates from the other subunits

Question 16

What brings about the physiologic response with G protein coupled receptors?

Answer 16

The alpha-GTP complex

Question 17

Other than separation of the chemical signal from the receptor site, what ceases physiologic response in G protein coupled signal transduction?

Answer 17

A dephosphorilating enzyme in the alpha subunit breaks down GTP to GDP. The alpha/GDP complex reconnects with the G protein which reconnects to the receptor and becomes inactive.

Question 18

What type of receptors use G protein coupled receptors

Answer 18

Alpha 1
Beta 1
Beta 2

Question 19

Activated Alpha 1 receptor alpha/GTP complex activates what enzyme?

Answer 19

Phospholipase C

Question 20

Activated Phospholipase C converts PIP2 into what two substances?

Answer 20

Diacylglycerol

IP3

Question 21

IP3 causes increased release of _______ form sarcoplasmic/endoplasmic reticulum

Answer 21

Calcium

Question 22

Diacylglycerol and the Calcium released from IP3 stimulation activate ___________ to get target cell response.

Answer 22

Protein kinase C

Question 23

Alpha 1 receptors are found predominantly where?

Answer 23

Vascular smooth muscle

Question 24

Pure A1 agonist drug

Answer 24

Neosynephrine

Question 25

Activated A1 response brings about what physiologic actions

Answer 25

Vascular smooth muscle contraction - Vascular constriction - Increase BP

Question 26

B1 receptors are found where in the heart?

Answer 26

SA node AV node Ventricular contractile fibers

Question 27

Activated B1 in the SA node causes:

Answer 27

Increased HR

Question 28

Activated B1 in the AV node causes:

Answer 28

Increased speed of conduction

Question 29

Activated B1 in ventricular contractile fibers causes:

Answer 29

Increased contractility

Question 30

B2 receptors are found where?

Answer 30

Bronchiolar smooth muscle

Question 31

Activated B2 in bronchial smooth muscle causes:

Answer 31

Bronchiolar dilation and increased airflow

Question 32

What is a common B2 agonist we use for bronchiolar dilation?

Answer 32

Albuterol

Question 33

The alpha/GTP subunit activates what enzyme in B receptors

Answer 33

Adenylyl cyclase

Question 34

Adenylyl cyclase converts ATP to cAMP in order to activate what enzyme to bring about physiologic response to activated B receptor

Answer 34

Protein kinase A

Question 35

If a receptor is phosphorilated to activate intracellular proteins, that means that _______ is added to bring about target cell response.

Answer 35

Energy is added to bring about target cell response

Question 36

What steroid-based hormones use intracellular receptor mechanisms

Answer 36

``` Testosterone Aldosterone Progesterone Estrogen Cortisol ```

Question 37

What hormones also use intracellular receptor mechanism, but is not steroid based?

Answer 37

Thyroid hormones

Question 38

A steroid based hormone crosses the cell membrane to bind with intracellular receptor, what does the hormone/receptor complex do next?

Answer 38

Moves through nuclear pores into the nucleus

Question 39

Once in the nucleus, the aldosterone/receptor complex attaches to DNA and activates ____________.

Answer 39

Transcriptases

Question 40

Transcriptases are enzymes that do what?

Answer 40

Increase the rate of transcription of DNA to mRNA

Question 41

What does mRNA have to do in order to synthesize proteins?

Answer 41

Leave the nucleus and carry the code to synthesize proteins

Question 42

What brings about the target cell response in intracellular receptor mechanisms?

Answer 42

The proteins synthesized/produced.

Question 43

Intracellular receptor mechanisms take seconds to minutes to work. TRUE/FALSE?

Answer 43

FALSE | Take hours to days to work, but last longer than other mechanisms

Question 44

What vasodilating substances use membrane bound receptor and intracellular receptor signal transduction mechanism?

Answer 44

Histamine Bradykinin Prostaglandins Adenosine

Question 45

Signal transduction via opening of cell membrane ion channels is the fastest signal transduction mechanism by far, this occurs in ___________

Answer 45

Milliseconds

Question 46

Signal transduction mechanisms coupled with second messengers, G-proteins, and phosphorylation of intracellular proteins/enzymes all occur take how long to get target cell response?

Answer 46

Seconds to minutes

Question 47

Intracellular receptors take how long to get target cell effect?

Answer 47

Minutes, hours or days, but long-lasting effects.