Functions of the Nervous System

Question 1

What are the 2 main divisions of the nervous system?

Answer 1

• CNS - areas surrounded by meninges
• Peripheral NS

Question 2

What are the 2 divisions of the peripheral NS?

Answer 2

• SOMATIC - controls aspects under voluntary control
• AUTONOMIC - not under voluntary control i.e (para) sympathetic

Question 3

What are the roles of the following:
- Cerebral cortex
- Hypothalamus
- Brainstem
- Cerebellum

Answer 3

• CEREBRAL CORTEX - thoughts, emotions, memories, processes sensory information
• HYPOTHALAMUS - processes information related to internal homeostasis
• BRAINSTEM - contains midbrain, pons, medulla
• CEREBELLUM - fine movement

Question 4

Describe spinal nerves.

Answer 4

• Formed from dorsal root - carries sensory information to CNS
• Formed from ventral root - carries motor information away

Question 5

Describe sensory neurons.

Answer 5

• Pseudounipolar
• Cell body sits at side of axon projection
• Cell body exists in dorsal root ganglion

Question 6

Describe general nervous structure.

Answer 6

• Covered in thick membrane called epineurium
• Inside are fascicles containing hundreds of axons (each wrapped in endoneurium)
• Fascicles wrapped in perineurium

Question 7

Describe the following:
- MULTIPOLAR NEURONS
- BIPOLAR NEURONS
- PSEUDOUNIPOLAR NEURONS

Answer 7

• MULTIPOLAR - dendritic network attached to cell bodies. Most common type
• BIPOLAR - extended dendritic arm
• PSEUDOUNIPOLAR - dendritic extension and axon fused during development. Sensory neurons.

Question 8

Describe synaptic transmission. PART 1

Answer 8

• Arrival of action potential triggers VGCC opening - influx of calcium ions down concentration gradient
• Raised intracellular calcium
• Neurotransmitter filled vesicles moves towards presynaptic membrane

Question 9

Describe synaptic transmission. PART 2

Answer 9

• Movement and fusion of vesicles due to coupling of SNAP proteins to vesicle proteins to form SNARE complex

Question 10

Describe synaptic transmission. PART 3

Answer 10

• Neurotransmitters released into synaptic cleft and bind to post-synaptic receptors e.g conformational shift of receptor and ion influx in LGICR

Question 11

Describe excitatory neurotransmission.

Answer 11

• Neurotransmitters binds to receptor causing influx of cations
• Membrane potential raised closer to threshold potential
• Membrane depolarisation
• On reaching threshold, action potential triggered

Question 12

Define inhibitory neurotransmission.

Answer 12

OPPOSITE TO EXCITATORY NEUROTRANSMISSION

Question 13

What outflow do the sympathetic and parasympathetic nervous systems demonstrate?

Answer 13

SYMPATHETIC - thoracolumbar outflow
PARASYMPATHETIC - craniosacral outflow

Question 14

Outline the distribution of nerves in the sympathetic nervous system.

Answer 14

• Pre-ganglionic neurons in spinal cord
• Exit through spinal nerves and synapse at sympathetic ganglia

Question 15

Describe the behaviour of neurons at ganglia.

Answer 15

• Pre-ganglionic neurons synapse with post-ganglionic neurons
• Innervate target organ

Question 16

What do the sympathetic neurons release?

Answer 16

• PRE-GANGLIONIC - Acetylcholine on nicotinic receptors
• POST-GANGLIONIC NEURONS - Noradrenaline onto adrenergic receptors (EXCEPTION - Salivary glands - release ACh)

Question 17

What do the parasympathetic neurons release?

Answer 17

• PRE-GANGLIONIC - Acetylcholine onto nicotinic receptors
• POST-GANGLIONIC - Acetylcholine onto muscarinic receptors

Question 18

How is the somatic nervous system different from autonomic nervous system?

Answer 18

NO GANGLIA - project directly towards target organ
- Release ACh onto nicotinic receptors

Question 19

The primary control centres of the ANS are the hypothalamus and medulla. What do they do?

Answer 19

• HYPOTHALAMUS - receives inputs from brain to inform it of threats. Communicates response to medulla
• MEDULLA - regions connecting to (para)sympathetic nerves.

Question 20

Describe autonomic reflexes with an example.

Answer 20

• Automatic responses to changes in homeostatic processes regulated by ANS
• EXAMPLE: Light being shone into pupil. Detected by photoreceptive ganglion cells - activates PNS. Pupil constricts.