lecture 3

Question 1

describe the nervous system

Answer 1

has neurotransmitters
released locally
responds to nerve impulses
affect muscles, glands, other neurons
within milliseconds

Question 2

describe endocrine system

Answer 2

has hormones
delivered through blood
throughout body
takes seconds, hrs, or days

Question 3

what is the simplest form of cell communication?

Answer 3

gap junctions
is direct connection that allows small molecules to pass from 1 cell to another

Question 4

2 forms of local communication

Answer 4

when target cell is close
autocrine- cell secretes a chemical, binds to self, e.g. cytokine
paracrine- cell secretes chemical into ECF, acts on nearby target cell , e.g. response to allergens

Question 5

form of distant communication

Answer 5

endocrine system + hormones
Endocrine organ releases hormones into blood for transport to target cell
E.g. Pituitary hormones act on gonads
Distance does create a delay, BUT act on several sites
E.g. Adrenal gland act on limbs, heart, CNS

Question 6

steps of synaptic transmission

Answer 6

process at synapse, neurotransmitters released from axon terminals into synaptic cleft, diffuse across to dendrites of next cell
Passes along a signal- inhibit/excite a cell, or modify the cell
Very fast
Steps
1. Action potential reaches axon terminal
2. Calcium channels open
3. Ca2+ causes vesicles to release neurotransmitter
4. Neurotransmitter crosses synapse
5. Neurotransmitter binds to neuroreceptors
6. Trigger signal in post-synaptic neuron

Question 7

3 types of hormones

Answer 7

Normal hormones come from endocrine cell
Neurohormones come from a neuron
Lipid soluble hormones move into cell to act with INTRAcellular receptors- influencing transcription

Question 8

3 stages of cell signalling

Answer 8

Only cells with right receptors will respond
3 stages
1. Reception- signal molecule binds to receptor
2. Signal-transduction- when molecule binds to receptor, changes receptor to transmit info.
3. Cell response- cell responds to the info.

Question 9

what are ligands

Answer 9

Molecules that bind to a receptor on or within cell
Binding is specific + reversible
Ligand may or may not activate
Activation affects cell function
Primary ligand + agonist- activate receptor
Antagonist- NEVER activates receptor

Note: agonist- changes shape of receptor

Question 10

what can receptor activation do

Answer 10

• Change permeability
• Change cell activity
• Gene expression
• Open/closing of ion channel