Chap 5(Signal Transduction Mechanisms) Flashcards Preview

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Flashcards in Chap 5(Signal Transduction Mechanisms) Deck (32)
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1
Q

What is signal transduction mechanism?

A

Process by which messenger binding to receptor produces response in target cell

2
Q

Signal transduction mechanism differs based on what ?

A

whether messenger is lipophilic or lipophobic

3
Q

Lipophillic Messenger located where?

A

Receptor inside cell

4
Q

Lipophobic messenger located where?

A

Receptor on plasma membrane

5
Q

Lipophillic messengers bind to receptor where? What occurs if it is in cytoplasm?

A

In cytoplasm or nucleus.

Receptor :messenger complex enters nuclues

6
Q

Lipophobic messengers bind to what?

A

Membrane-bound receptors

7
Q

Define signal transduction.

A

the transmission of molecular signals from a cell’s exterior to its interior

8
Q

Lipophobic messengers , receptors fall into three categories, name them.

A

Channel linked receptors
Enzyme linked receptors
G protein linked receptors

9
Q

What is a channel linked receptor

A

Receptor that opens/closes ion channels in response to messenger binding

10
Q

Can gated ion channels open and close?

A

Yes.

11
Q

Ligand- gated channels open or close in response to what?

A

Binding of ligand to receptor

12
Q

What is a ligand?

A

Messenger that bind to recepto/channel

13
Q

Channel-linked receptor is what ?

A

Type of ligand- gated channel

14
Q

Open channel means what ?

A

Increased permeability

15
Q

Fast channels mean what

A

Receptor and channel are the same protein

16
Q

Slow channels mean what?

A

Receptor coupled to channel by G protein

17
Q

What is the role of calcium in signal transduction (4)

A

Changes electrical properties of cell
Induces muscle contraction
induces secretion by exocytosis
binds to calmodulin

18
Q

Ca-Calmodulin complex activates what ?

A

Protein Kinase

19
Q

Calcium levels cytosol and extracellular fluid

A

Lower in cytosol

20
Q

Calcium level is maintained at low level because of:

A
  1. active transport of calcium across membrane.
  2. Sequestration of calcium by binding with proteins in cytosol.
  3. active transport of calcium into certain organelles( Smooth endoplasmic reticulum and mitochondria)
21
Q

How are calcium levels in cytosol increased?

A

by opening ion channels or releasing intracellular stores

22
Q

Enzyme linked receptors special how?

A

Function as enzyme and receptor

23
Q

Most enzyme linked receptors are

A

tyrosine kinase

24
Q

Purpose of G protein

A

function as links between G-protein-linked receptors and other proteins in plasma membrane called effectors.

25
Q

What is a second messenger?

A

An intracellular messenger produced by binding of an extracellular messenger to a receptor

26
Q

How is second messnger produced? Involves what?Purpose?

A

Binding of first messenger to receptor leads to production of second messenger in the cytosol. G-proteins. Amplification.

27
Q

What is phosphodiesterase?

A

Enzyme that degrades c-AMP

28
Q

What is the amplifier enzyme?

A

Guanylate Cyclase

29
Q

What is Phosphatidylinositol biphosphate (PIP2)

A

Membrane phospholipid

30
Q

What is phospholipase C? Activated by what?

A

Amplifier enzyme. G protein.

31
Q

How does termination of message occur?

A

Enzymatic degradation of messenger
Diffusion of messenger away from receptor
Internalization of messenger-receptor complex
Removal of calcium from cytosol

32
Q

How does signal transmission occur in endocrine system?

A

Endocrine gland releases hormone into blood

Travels to distant target cells