cell signalling

Question 1

what is Homeostasis?

what is it regulated by?

Answer 1

physiological processes that are regulated between ranges

regulated by + and - feedback loops

Question 2

how do cells communicate with other cells?

Answer 2

via cell signalling

Question 3

most cells signals are what?

Answer 3

chemical

Question 4

what is the characteristics of direct cell signalling?

Answer 4

signaling cell and target cell are connected by gap junctions

signal is passed directly from one cell to another

Question 5

What are the characteristics of indirect cell signalling? (5)

Answer 5

Signaling cell releases chemical messenger

Chemical messenger carried in extracellular fluid

Chemical messenger binds to a receptor on target
cell

Activation of signal transduction pathway or ion
channel

Response in target cell

Question 6

Gap junctions:

what are the specialized protein complexes called and what do they do?

Answer 6

called connexins

create an aqueous pore between adjacent cells

Question 7

Gap junctions:

what do gap junctions transport?

what does this do?

Answer 7

Movement of ions between cells

Changes in membrane potential

Chemical messengers can travel
through the gap junction
Example: cAMP

Opening and closing of gap junction
can be regulate

Question 8

Indirect signalling:
Short distance

What is Paracrine

what is Autocrine

Answer 8

Paracrine:
chemical messenger diffuses to nearby cell

Autocrine:
chemical message diffuses back to signalling cell

Question 9

Indirect signalling:

Short distance uses what?

Answer 9

paracrine and autocrine

Question 10

indirect signalling doing long distances uses what?

Answer 10

Endocrine system and the Nervous system

Question 11

indirect signalling:

how does the endocrine system work?

Answer 11

uses chemical messengers (hormones) that are transported by circulatory system

Question 12

Indirect signalling:

how does the Nervous system work?

Answer 12

it uses electrical signals that travel along neurons and a chemical messanger (NT) is released

Question 13

What are the three steps in indirect signalling?

Answer 13

Three steps
Release of chemical messenger from signaling cell
(gland)

Transport of messenger through extracellular
environment to target cell

Communication of signal to target cell

Question 14

what are the classes of chemical messengers (7)

Answer 14

Classes of chemical messengers

Peptides (insulin, glucagon, atrial natriuretic peptide, vasopressin)

Steroids (testosterone, estrogen, aldosterone, cortisol)

Amines (norepinephrine, epinephrine, triiodothyronine, thyroxine)

Lipids (eicosanoids: prostaglandin, leukotrienes)

Purines (AMP, ATP, GMP)

Gases (nitric oxide)

Amino Acids (glutamate, aspartate, glycine, GABA)

Question 15

the structure of the chemical messenger affects what?

what structural change has the largest affect?

Answer 15

affects signalling mechanism

hydrophilic and hydrophobic

Question 16

Peptide Protein Hormones:

what are they composed of?

Answer 16

composed on AA

Question 17

Peptide Protein Hormones:

Where are they synthesized?

Answer 17

On the rough ER often as larger preprohormones

Question 18

Peptide Protein Hormones:

where are they stored?

Answer 18

Stored in vesicles as prohormones

Question 19

Peptide Protein Hormones:

how are they secreted?

Answer 19

secreted by exocytosis

Question 20

Peptide Protein Hormones:

what is their chemical structure?

Answer 20

Hydrophilic
soluble in aqueous solutions
travel to target cell and dissolve in extracellular fluid

Question 21

Peptide Protein Hormones:

where to they bind?

Answer 21

bind to transmembrane receptors

signal transduction

have rapid effects on target cells

Question 22

Steroid Hormones:

what are they derived from?

Answer 22

Cholesterol

Question 23

Steroid Hormones:

what are they synthesized by?

Answer 23

The smooth ER OR mitochondria

Question 24

Steroid Hormones:

What are the three classes?

Answer 24

Mineralocorticoids (aldosterone)
- Electrolyte balance

Glucocorticoides (cortisol, cortisone, corticosterone)
- Stress hormones

Reproductive hormones (estrogen, progesterone, testosterone)
-Regulate sex-specific characteristics

 Molting hormone (ecdysone)
- Insects shed hard exoskeleton during molting

Question 25

What are some characteristics of steroid hormones? (8)

Answer 25

Hydrophobic

Can diffuse through plasma membrane

Cannot be stored in the cell

Must be synthesized on demand

Transported to target cell by carrier proteins
Example: albumin

Bind to intracellular or transmembrane receptors

Slow effects on target cell (gene transcription)

Stress hormone cortisol has rapid non-genomic effects

Question 26

What are amine hormones?

Answer 26

Chemicals that possess amine group

• some true hormones, some neurotransmitters, some both
• most hydrophilic (thyroid hormones are hydrophobic)

Question 27

What is paracrine signalling?

Answer 27

form of cell to cell communication in which a cell produces a signal to induce change in nearby cells, altering the behaviour of cells