The Autonomic Nervous System

Question 1

Efferent

Answer 1

Conducting/carrying outgoing signals

• carries signals from the brain/spinal cord to periphery
• motoneurone or autonomic neurone

Question 2

Ganglion

Answer 2

• collection of neuronal cell bodies in the PNS
  PRE-ganglion neurone
• neurone immediately proximal to the ganglion
  POST-ganglion neurone
• neurone immediately distal to the ganglion

Question 3

Effector

Answer 3

• target organ through which the nervous system exerts its action

Question 4

The CNS

Answer 4

Encasement of the cranium and vertebral column (by bony structures)
Suspended in cerebrospinal fluid
Responsible for the sophisticated functions of the nervous system

Neurones in CNS known as pre-ganglionic
Axons are myelinated
White Rami communicates

Question 5

The PNS

Answer 5

The nervous system outside of the CNS
Connects the CNS to target organs and sensory organs to the CNS

Neurones in PNS known as post-ganglionic
Stroma cause swellings known as ganglia
Axons are not myelinated
Grey Rami communicates

Question 6

The somatic nervous system

Answer 6

Somatic efferents are under voluntary control

- are underdeveloped at birth so can be programmed by the environment

Question 7

The autonomic nervous system

Answer 7

Becomes active with organogenesis and doesn’t stop during life
Balance between the sympathetic and parasympathetic systems
- establishes and maintains homeostasis
- autonomic tone varies between SNS and PNS dominance
- sweat glands only receive sympathetic drive
Overactivity of PNS = dilated blood vessels, shortage of substrate to brain, fainting
Overactivity of SNS = constriction of blood vessels - necrosis of body extremities

Question 8

The sympathetic nervous system

fight or flight system

Answer 8

Expressed in stressful situations
- expenditure of energy
- diversion of blood to muscle and heart
- increased heart rate
- increased blood pressure
- reduced blood flow to skin and gastrointestinal tract
From the spinal cord only
- all 12 thoracic segments and the first 2 lumbar segments
- thoraco-lumbar division of ANS
- cholinergic

Question 9

The parasympathetic nervous system

the rest and digest system

Answer 9

• reduced heart rate and force of heart contraction
• promotes digestion
• promotes emptying of bladder
• promotes sleep
  From brain and spinal cord
• cranial nerves (III, VII, IX, X)
• sacral spinal cord levels (S2, S3, S4)
• the Cranio-Sacral division
  Post ganglionic (cholinergic and express nicotinic receptors)

Question 10

Afferent

Answer 10

Conducts/carries incoming signals

• from periphery to CNS
• sensory neurones