Chapter 5(Mechanisms of inter cellular communication)

Question 1

What is a gap junction? What about coupling ?

Answer 1

link adjacent cells and are formed by plasma membrane proteins called connexins. Electrical impulse directly to the other cell. Direct electrical and metabolic coupling

Question 2

Where are gap junction common?

Answer 2

smooth and cardiac muscle

Question 3

How do chemical messengers work?

Answer 3

When one cell releases a chemical into the interstitial fluid and another cell called the target cell responds to it.

Question 4

Explain Paracrines and give an example.

Answer 4

Released by cell, moves to target cell by diffusion

Paracrines- act on neighboring cells. Histamine.

Question 5

What are autocrines?

Answer 5

Act on the cell that releases it.

Question 6

What is a neurotransmitter? Two properties of it.

Answer 6

Messenger of nervous system.
Diffuses to very close target cell
Released from neuron by exocytosis

Question 7

What is the site called where junction occurs between neurotransmitter and cell?

Answer 7

Synapse.

Question 8

Give an example of neurotransmitter and how it works?

Answer 8

Acetylcholine, causes contraction of skeletal muscle.

Question 9

What are hormones? Two properties of them.

Answer 9

Chemical messenger of the endocrine system.
Released from endocrine gland into blood
Transported in blood to target

Question 10

What are the target cells for hormones?

Answer 10

cells in body with receptors specific to the hormone

Question 11

What are neurohormones?

Answer 11

Released from neuron into blood where it acts in manner similar to hormones

Question 12

What are cytokines classified as

Answer 12

peptide/ protein

Question 13

4 characteristics of cytokines

Answer 13

Can be transported in blood
Released by most cell types
Involved in cell development, differentiation, and immune response
Often act on a wide range of targets

Question 14

What is the most important chemical characteristic?

Answer 14

Whether or not the messenger can dissolve in water or cross the lipid bilayer in the plasma membrane.

Question 15

Two classifications and why?

Answer 15

Lipophillic. Lipid soluble and can cross plasma membrane- do not dissolve in water.
Hydrophilic. water soluble and do not cross plasma membrane.

Question 16

Name the chemical classes of messengers. 5.

Answer 16

Amino acids
Amines
Peptides
Steroids
Eicosanoids

Question 17

What do amino acids function as? What are the 4? Lipophillic or hydrophillic?

Answer 17

Neurotransmitters. Glutamate
Aspartate
Glycine
GABA (gamma-amino butyric acid)
Hydrophillic.

Question 18

What are amines derived from? What group do they include?

Answer 18

Amino acids. Catecholamines, derived from tyrosine.

Question 19

Examples of amines.

Answer 19

Dopamine, norepinephrine, epinephrine

Question 20

Serotonin derived from? Histamine? Thyroid hormones?

Answer 20

Tryptophan, histadine, tyrosine

Question 21

Amines except for thyroid hormones are all?

Answer 21

Lipophobic.

Question 22

What is Most abundant class of chemical messengers
Lipophobic?

Answer 22

peptide/ protein. Yes.

Question 23

Peptide usually refers to what?

Answer 23

Chains smaller than 50 amino acids.

Question 24

proteins are usually what?

Answer 24

more than 50 amino acids.

Question 25

Steroid messenger derived from what?

Answer 25

Cholesterol.

Question 26

All of the steroid messengers function as what?

Answer 26

Hormones

Question 27

Steroid lipophillic or lipophobic?

Answer 27

Lipophillic.

Question 28

Lipophillic messengers released how? How is release regulated?

Answer 28

Diffusion. By regulating rate of synthesis

Question 29

Lipophobic messengers released how

Answer 29

Exocytosis

Question 30

How many amino acids are essential? How many produced by body? How many of those are neurotransmitters

Answer 30

9,11,3

Question 31

After amino acid synthesis, neurotransmitters transported into where?

Answer 31

Secretory vesicles.

Question 32

What is synthesized from glucose ?

Answer 32

Glutamate and aspartate

Question 33

What is GABA synthesized from

Answer 33

glutamate

Question 34

All amines derived from Synthesized where?

Answer 34

Amino Acids. In the cytosol.

Question 35

Which chemicals diffuse through interstitial fluid?

Answer 35

Paracrines, autocrines,most Ctyokines and neurotransmitters

Question 36

Which chemical are transported in blood?

Answer 36

Hormones, neurohormones and some cytokines

Question 37

To be transported in dissolved form, messenger must be?

Answer 37

Hydrophillic

Question 38

How long a hormones persists in the blood depends on?

Answer 38

The half-life of that hormone