Lecture 16 - general principles of cell signalling

Question 1

2 reasons why cell communication is importnant

Answer 1

• adapting to environmental changes via changes to cell function
• promoting development or injury repair by coordinating cell differentiation and growth

Question 2

what are the 2 general catgories of signals

Answer 2

1. cell to cell contact
2. free diffusion of ligands between either adjacent cells or distant cells

Question 3

mechanism of signalling by cell to cell contact

Answer 3

NO release of secreted molecules
- only membrane bound signal receptor interactions
- this is common in immune system

Question 4

what are the 2 types of signalling by diffusion of ligands

Answer 4

signals that CAN and CANT cross the plasma membrane

Question 5

example of singals that can cross the plasma membrane

Answer 5

hydrophobic small molecules
bind to receptors inside the cell
e.g. nuclear receptor hormones

Question 6

what are the two ways specificity is achieved with signals that can cross the plasma membrane

Answer 6

1- steroid binding domain
2- DNA binding domain

Question 7

ecamples of signals that cant cross the plasma membrane

Answer 7

hydrophillic or bid e.g. peptides/proteins such as insulin, FSH, growth factors

Question 8

what is paracrine signalling

Answer 8

local signalling
within one tissue
signals diffuse over short distance to neighbouring cells
e.g. epidermal growth factor

Question 9

what is neuronal signalling

Answer 9

local signalling
between 2 cells in synaptic cleft
via neurotransmitter

Question 10

what is endocrine signalling

Answer 10

remote signals = act over the whole body via blood stream
endocrine cells make hormones

Question 11

example of 1 signal 2 responses

Answer 11

signal = ACh
receptor = either nicotinic or muscarinic ACh receptor
- nicotinic = contraction in skeletal muscle cells
- muscarinic = decreases rate and contractility of heart

Question 12

example of 1 signal and 1 receptor BUT diff transmission differs between cell types

Answer 12

muscarinic ACh receptor
in heart muscle cell = dec rate and contractility
in salivary gland = secretion

Question 13

3 major receptor families

Answer 13

1. ion-channel-coupled receptors
2. g-protein coupled receptors
3. enzyme-coupled receptors

Question 14

general mechnanism of enzyme coupled receptors

Answer 14

• signal activates catalytic activity of a receptor’s intrinsic or associated enzyme