Physiology - ANS/CVS

Question 1

Emotion pathway?

Answer 1

1. Antecedent
2. Appraisal
3. Emotion
4. Interoceptoin/Proprioception
5. Subjective experience
6. Memories/Emotions
7. Repeat

ANS links emotional experience to physical response

Question 2

Reflex loop

Answer 2

Reflex - response to stimulus

Levels of integration
1. Enteric nervous system/effector organ (local response)
2. Ganglion: sensory, preganglionic and interneurons
3. Spinal cord: integrates across spinal levels
4. Brain stem: integrates across organs
5. Higher centers (hypothalamus): integrates with motivation and desires

Negative feedback
- opposes initial changes
- forms the basis of homeostatic responses

Question 3

Parasympathetic vs. sympathetic vs. enteric

Answer 3

Parasympathetic (brake)
- dominant at rest
- sense visceral inputs

Sympathetic (accelerator)
- dominant in fight or flight
- senses pain to trigger responses

Enteric
- controls gut motility and secretion

Question 4

Basic plan of efferent (carries away) ANS

Answer 4

Pathway
1. central nervous system
2. preganglionic neuron
3. peripheral ganglion
4. postganglionic neuron
5. target cell

Question 5

Organisation

Answer 5

Parasympathetic
- long preganglionic axon (extends to organ)
- short ganglionic

Sympathetic
- short preganglionic
- long postganglionic axon (extends to organ)

Question 6

System divisions

Answer 6

Pathway:
1. spinal cord
2. sympathetic chain
3. collateral ganglion
4. effector organ
- for broad: sympathetic chain
- for specific: collateral ganglia
- general effects: mediated by adrenaline from adrenal medulla

Parasympathetic:
- operates on collateral ganglion model (ganglion near target organs)

Question 7

Autonomic synapses

Answer 7

• similar to NMJ
• each neuron forms many synapses on target tissue, producing strong effects through multiple release sites
• synaptic cleft is wider, allowing more neurotransmitter spillover

Question 8

Neurotransmitters

Answer 8

Parasympathetic
- postganglionic neurons release ACh
- binds to muscarinic (M) receptors
- metabotropic, acts via second messengers

Sympathetic
- postganglionic neurons release noradrenaline (norepinephrine) or adrenaline (epinephrine), binding to alpha and beta receptors
- multiple neurotransmitters can be released, producing varied effects depending on rate of axon activity

Question 9

ANS in action

Answer 9

Baroreceptors - specialised neurons that detect vessel stretch (response to blood pressure changes)
- synapse in brainstem cardiovascular centres

Response to low blood pressure
- increased sympathetic activity -> peripheral vascoconstriction -> restores blood pressure
- reduced parasympathetic activity -> increases heart rate to support blood pressure restoration