Sympathetic and Paradympathetic NS

Question 1

Sympathetic NS

Answer 1

• mobilizes body during extreme situations (fight or flight)
• shunts blood to active skeletal muscles, brain, and heart
• stimulates liver to breakdown glycogen for ATP synthesis
• dilates bronchioles
• increases HR

Question 2

Sympathetic NS structure

Answer 2

• fibres originate from thoracic or lumbar spinal nerves (thoracolumnar division)
• cell bodies in lateral horns, axons exit through the ventral root and enter the spinal nerve
• they pass through Tanya communication
• enter synaptic trunk ganglion (or synaptic chain, lies along the vertebral column)
• can synapse with post-ganglionic axon or continue without synapsing, forming the Splanchnic nerve
• Splanchnic nerve synapses with the collateral ganglion which serves visceral organs

Question 3

Unique roles of the sympathetic NS

Answer 3

• adrenal medulla: releases E and NE
• blood Vessels: constricts vessels serving viscera and skin dilated vessels serving skeletal muscles
• sweat glands: stimulates sweating
• kidneys: decrease urine output
• arrector pili muscles: causes hair to stand

Question 4

Parasympathetic NS

Answer 4

• promotes maintenance and conserves energy
• “rests and digests”: slows HR, stimulates digestion, stimulates secretion from glands
• SLUDD: salivation, lacrimation, urination, defecation, digestion

Question 5

Parasympathetic NS structure

Answer 5

• fibres originate from cranial nerves or sacral spinal nerves (craniosacral division)
• cranial: pre-ganglion IV neuron synapses with post-ganglionic neurons close to its effector
• sacral: pre-ganglionic axon leaves the spinal cord and become the pelvic nerves. Once in the pelvic cavity, they synapse with a second motor neuron close to the organ they serve
• postganglionic neuron releases ACh