Question

1. Describe the effect of aging on the ANS?

2. What effect would cutting the vagus nerve branch that innervates the stomach have on gastric function?

3. In what ways are the autonomic nervous system and the somatic nervous system different?

Answer 1

1) Aging has following effects on Autonomic nervous system or Visceral nervous system: :

1. Generalised changes that result in aging are loss of neurons,loss of axon branches alterations in neurotransmitters e.t.c
2. Impaired ability to adapt to environment stresses everyday (or) intrinsic visceral stimuli with increasing age.
3. Decrease in neurotransmitter receptor action that lead to diminished autonomic activity(blood pressure and cerebral blood flow regulation are some examples) and poorly coordinated Autonomic discharge(Bladder funtion).when plotted continuously over time,the beat to beat heart rate /BP signal is highly irregular due to interactions of multiple autonomic control systems operating over different time scales.
4. Mediations that acutely lower BP may also contribute to hypotension(orthostatic hypotension is an important autonomic failure).

2) Vagus nerve plays a very important role in Gastric secretion,the tonic impulses in vagus nerve result in continuous or basal secretion i.e in simple terms the effect of cutting the vagus nerve branch that innervates the stomach would result in decresed or no secretion of gatric juice that indirectly has a ill digestion of protiens (due to lack of HCl to activate pepsinogen that digest proteins).

3)Differences in Autonomic and Somatic nervous system

Criteria	Autonomic nervous system(ANS)	Somatic nervous system(SNS)
Associated with	Control of visceral function that occur below the level of consiousness.	Voluntary control of body movements through skeletal muscles and mediation of involuntary reflex arcs.
Organisation/Anatomy	A preganglionic autonomic neuron passes from CNS to atonomic ganglion,where it synapses with a second post ganglionic neuron and this post ganlionic neuron innervates the smooth muscle ,cardiac muscle or gland.	In contrast to ANS a single motor neuron passes from CNS to skeletal muscle.

CNS-Central nervous system

Additional differences includes

effector at rest has intrinsic tone	Effector at rest is flaccid
Basefiring speeds up when stimulated	No firing at rest
Neurotransmission is stimulatory or Inhibitory	Always stimulatory
Acetylcholine and Norepinephrine is released at synapse	Only acetylcholine released at synapse