Cell communication

Question 1

Types of cell signaling

Answer 1

• autocrine
• paracrine
• endocrine & neuroendocrine
• synaptic

Question 2

Long distance communication signal

Answer 2

-Hormone & neurotransmitter

Question 3

Autocoid

Answer 3

• local hormone
• not to be confused with hormone
• autocoids acts on neighbouring cell, doesn’t need blood to be transported

Question 4

Synaptic Signalling

Answer 4

The chemical messengers are called neurotransmitters that transmit signals between adjacent neurons (extremely close)

Question 5

Synaptic signalling differ from hormone signalling in that

Answer 5

• Neurotransmitters can achieve very high local concentrations
• Associated with rapid, short-term responses
• Neurotransmitters are quickly degraded or taken back into the cell

Question 6

What happens when Na+enters cell?

Answer 6

• It causes the membrane to depolarize slightly (becomes more positive)
• Raising the membrane potential from -70mV closer to the action potenti

Question 7

What happens when Cl- enters cell?

Answer 7

• makes the membrane potential slightly more negative than -70mV, known as hyperpolarization.
• the membrane potential is now even further away from the threshold potential, making it harderr for an action potential to be initiated

Question 8

Ligand-binding & voltage-gated channel method of triggering cellular response

Answer 8

• By changing the ion concentration gradient inside and outside of the cells
• ie Na+, K+ and Ca2+

Question 9

Ligand-gated ion channels

Answer 9

• when the correct ligand binds, the protein undergoes a conformational change
• channel is open in which ions can enter the cell
• suited as synaptic receptors b/c try open very rapidly in response to ligand binding, essential for propagating nerve transmission

Question 10

Voltage-gate ion channels

Answer 10

• activated by a change in the electrical potential difference at the cell membrane.
• found mostly at neuromuscular junction. ie sodium and potassium ion channel
• force of contraction is determined by calcium ion influx thru voltage gated calcium ion channel.

Question 11

G-protein-coupled receptors

Answer 11

• receptors that coupled with G-proteins
• responds to a stimulus and initiates a intracellular process (production of secondary messengers), results in a physiological response.
• The receptor is separate from effector
• energy is required to dissociate G-protein from receptors

Question 12

Type of G-protein Couple Receptors

Answer 12

• Gq (stimulatory)
• Gi (inhibitory)
• Gs (stimulatory)

Question 13

Gq

Answer 13

• stimulatory
• stimulates Phospholipase C (enzyme)
• increases Inositol Triphosphate (IP3) and DIacylglcerol (DAG)(both are second messengers)

Question 14

Gi

Answer 14

• inhibitory
• inhibits Adenylate cyclase (enzyme)
• decreases cAMP (second messenger)

Question 15

Gs

Answer 15

• stimulatory
• stimulates Adenylate (cyclase enzyme)
• increases cAMP (second messenger)

Question 16

Four MAIN types of receptors

Answer 16

• Ion channel (ligand or voltage gated)->autonomic receptor
• G-protein coupled receptor ->autonomic receptors

-Enzyme-linked receptors
ie tyrosine(protein)-kinase(enzyme receptor)

• Intracellular receptors –> receptors in cell (in nucleus or cytoplasm)
  ie. nuclear receptor (steroid receptor