Nervous System

Question 1

Organisation

Answer 1

CNS
- brain
-spinal chord
PNS
- sensory system
- somatic system
- autonomic system
- enteric
- sympathetic
- parasympathetic

Question 2

Autonomic organisation

Answer 2

Contains all motor outputs from the CNS apart from those to skeletal muscles

Pathways contains 2 neurones in series:
- pre ganglionic neurone - cell body in CNS and synapse in the automnic ganglion
- post ganglionic neurone - cell body in autonomic ganglion and synpase with the effector organ

Question 3

Role of sympathetic and parasympathetic nervous systems

Answer 3

Regulating the internal environment

Function is to maintain homeostasis

Control cardiac function, endo/exorine glands

Sympathetic = fight or flight
Parasympathetic = rest and digest

Question 4

What does sympathetic do on organs……

Answer 4

Heart rate -> increase
Force of contraction -> increse
Blood vessels body -> constrict
Blood vessels skeletal -> dilate
Blood pressure -> increase
Bronchi smooth muscles-> constrict
Gut motility -> decrease
Bladder -> relax/fill
Pupil -> dialte
Renin secretion -> decrease
Glucose generation -> increase
Exocrine Gand secretion - no effect

Question 5

What does parasympathetic do on organs……

Answer 5

Heart rate -> decrease
Force of contraction -> decrease
Blood vessels body -> no effect
Blood vessels skeletal -> constrict
Blood pressure -> derease
Bronchi smooth muscles-> relax
Gut motility -> increase
Bladder -> contract/empty
Pupil -> constrict
Renin secretion -> increased
Glucose generation -> decreased
Exocrine Gand secretion -> secrete

Question 6

2 major neurotransmitters of ANS

Answer 6

Acetylcholine - at target organ for parasympathetic nervous system

Noradrenaline - at target organ for sympathetic nervous system

Question 7

Acetylcholine

Answer 7

Acts at 2 receptor subtypes in the ANS:

• Nicotinic receptors
  - Ligand-gated ion channels activated by acetylcholine

Question 8

Noradrenaline

Answer 8

Acts at adrenoreceptors which are all GPCR’s

Question 9

2 subtypes of adrenoreceptors

Answer 9

Alpha and beta

Question 10

Where is synthesis of acetylcholine and what

Answer 10

Pre-synaptic terminal

Simple pathway:
Acetyl coA+choline —choline acetyltransferase —> acetylcholine + coA

CoA goes back to the start again

Question 11

Acetylcholine once synthesised

Answer 11

Taken into synaptic vesicles by a specific transporter in the vesicle membrane

Question 12

Acetylcholine released by

Answer 12

exocytosis after an action potential

Question 13

Acetylcholine broken down by

Answer 13

down in the syaptic cleft by the action of acetylcholinesterase into Choline + acetate

Choline is taken back into pre-synaptic thermal by a choline transporter

Question 14

Acetylcholine acts as 2 subtypes of receptor:

Answer 14

•Nicotinic receptors are ligand-gated ion channels (ionotropic receptor) - activated by acetylcholine

•Muscarinic receptors are G protein-coupled receptors (metabotropic receptor) - activated by acetylcholine

Question 15

What happens to salivary gland secretion is a muscarinic antagonist is used

Answer 15

Decrease in excretion

Parasympathetic usually increases it but if have antagonist at muscarinic ecepots; blocks it so less secretion

Question 16

What happens to HR if a muscarinic agonist is used

Answer 16

Acetylene choline slows HR so it would also decrease HR

Question 17

What is muscarinic agonist

Answer 17

Mimic action of acetylcholine on muscarinic receptors

Question 18

What is a muscrinic antagonist

Answer 18

Block binding of acetylcholine

Question 19

What happens o blood vessel smooth muscle if a drug is used that causes noradrenaline release

Answer 19

Noradrenaline increases BP so would constrict