Types of chemical messenger systems. Receptors and their activation. Second messenger mechanisms for mediating intracellular functions.

Question 1

types of chemical messenger systems

list

Answer 1

paracrine
autocrine
neurotransmitter
neuroendocrine
endocrine

juxtacrine
intracrine

Question 2

paracrine chemical messenger system

Answer 2

chemical messenger released by the main cell and acts upon nearby target cell

Question 3

paracrine chemical messenger characteristics

Answer 3

quick action
short response
local effect

Question 4

paracrine chemical messenger examples

Answer 4

growth factors
cytokines

Question 5

autocrine chemical messenger system

Answer 5

chemical messenger released by the cell and it acts on the cell that it was released from

Question 6

autocrine chemical messenger characteristics

Answer 6

local
self-regulated

Question 7

autocrine chemical messenger examples

Answer 7

interleukins in immune cells

Question 8

neurotransmitter chemical messenger system

Answer 8

chemical messenger released from presynaptic terminal -> synaptic cleft -> postsynaptic terminal

to nearby muscle cells/ nerve cells

Question 9

neurotransmitter chemical messenger characteristics

Answer 9

quick/ short term/ local

Question 10

neurotransmitter chemical messenger examples

Answer 10

Ach
serotonin
dopamine

Question 11

neuroendocrine chemical messenger system

Answer 11

chemical messenger released from neurosecretory cells into bloodstream

Question 12

neuroendocrine chemical messenger charateristics

Answer 12

rapid
prolonged

Question 13

neuroendocrine chemical messenger examples

Answer 13

ADH
oxytocin

Question 14

endocrine chemical messenger system

Answer 14

chemical messenger that is released from endocrine gland into bloodstream to reach target cell

to regulate
- growth
- metabolism
- reproduction

Question 15

endocrine chemical messenger characteristics

Answer 15

slow acting
widespread

Question 16

endocrine chemical messenger examples

Answer 16

insulin
thyroid hormones
cortisol

Question 17

juxtacrine chemical messenger system

Answer 17

chemical messenger released during direct cell to cell contact

for tissue development/ differentiation

Question 18

juxtacrine chemical messenger characteristics

Answer 18

specific
local

Question 19

juxtacrine chemical messenger example

Answer 19

membrane-anchoring ligands
in notch system

Question 20

intracrine chemical messenger system

Answer 20

chemical messengers acting WITHIN the cell without being secreted itself

Question 21

intracrine chemical messenger characterisitics

Answer 21

intracellular effects

Question 22

intracrine chemical messenger examples

Answer 22

cAMP

Question 23

receptors and their activation

list

Answer 23

g-coupled receptor protein

tyrosine-kinase receptor

ligand-gated ion receptor channel

Question 24

receptors and their activation

• g-coupled receptor protein

Answer 24

g-coupled protein receptor + ligand bind = conformational change
g-coupled protein changes shape which stimulates the activation of associate g-coupled protein

causing exchange of GDP with GTP on alpha subunits
causing modulation of downstream effectors
causing production of secondary chemical messengers

e.g. adrenergic receptors for adrenaline/ muscarinic receptors for Ach

Question 25

receptors and their activation

tyrosine kinase receptor

Answer 25

tyrosin kinase receptor binds to ligand
- dimerisation of receptor
- autophosphorylation of tyrosine

causing docking of signalling proteins with SH2 domain
causing activation of multiple signalling pathways like MAP kinase

example - insulin

Question 26

receptors and their activation

ligand-ion receptor channel

Answer 26

ligand ion channel receptor binds to ligand = conformation changes

• opening of ion channel
• flow of specific ions into the nerve cell + muscle cell to get excited
• stimulation of intracellular cascade events

e.g. GABA

Question 27

secondary messenger systems

list

Answer 27

cyclic AMP

IP3 + DAG

cyclic GMP

Question 28

secondary messenger systems -

cyclic AMP

Answer 28

g-coupled protein + ligand = conformational changes
stimulates g-coupled protein to change shape causing activation of asssociated g-coupled protein

causing activation adenlyl cylase
causing adenlyl cyclase helps convert ATP into cAMP

causing cAMP acts as a secondary messenger in the production of protein kinase A
causing protein kinase A phosphorylated target cells for cellular function

EXAMPLE

adrenaline and B-endergic receptors use cAMP to help break down glycogen in liver cells

Question 29

secondary messenger systems -

IP3 + DAG

Answer 29

g-coupled protein receptor + ligand = conformational changes
stimulates g-coupled protein to change shape causing activation of asssociated g-coupled protein

causing phospholipase C to activate
causing PIP2 into IP3 + DAG

IP3 - goes onto bind with IP3 receptors in ER to release calcium ions into cells
DAG - remains in membrane, combines with Ca2+ to activate protein kinase C
protein kinase C targets cells to alter activity

EXAMPLE
Ach and muscarinic cells

Question 30

secondary messenger systems -

cyclic GMP

Answer 30

g-coupled protein receptor binds to ligand = conformational changes
g-coupled protein receptor is now stimulated to activate associate g-couple protein

causing to stimulate guanlyl cyclase
causing GTP into cGMP

cGMP acts as secondary messenger for production of protein kinase G
protein kinase G targets cells to alter cellular activity

EXAMPLE
NO
- vasodilation
- relaxing of smooth muscles
- BP regulation