Nervous System 2

Question 1

Describe the somatic nervous system.

Answer 1

• Mainly controls voluntary movement
• Specifically refers to spinal nerves which control skeletal muscles

Question 2

What do visceral sensory neurones monitor?

Answer 2

Monitor temperature, pain, irritation, chemical changes and stretch in the
visceral organs

Question 3

State the function of visceral sensory fibres?

Answer 3

Conduct sensory impulses (usually pain or reflex
sensations) from the internal organs, glands, and blood vessels to the
central nervous system

Question 4

Describe the visceral reflex.

Answer 4

• It is the reflex arc of the autonomic nervous system which produces a glandular or non-skeletal muscular
  response in internal organs like the heart, blood vessels, organs in the gastrointestinal tract
• Many are spinal reflexes such as defecation and micturition reflexes
• Some only involve peripheral neurones: spinal cord not involved

Question 5

Describe the functions of the autonomic nervous system.

Answer 5

• Maintains internal environment
• Mostly involuntary
• Controls visceral functions
• circulation
• digestion
• excretion
• Modulates endocrine function

Question 6

What do ANS nerves control?

Answer 6

Mainly smooth muscle, cardiac muscle and secretory glands.

Question 7

What are the smooth muscles?

Answer 7

• Bronchioles
• iris
• Digestive system
• Bladder
• Vascular system

Question 8

What are the secretory glands?

Answer 8

• Adrenal medulla
• Pancreatic islets
• Salivary glands
• Sweat

Question 9

What is the function of cardiac muscle?

Answer 9

• Control heart rate
• Control contractile force

Question 10

What is the ANS divided into?

Answer 10

• Sympathetic
• Parasympathetic

Question 11

Describe the sympathetic division.

Answer 11

• ‘Fight or flight’
• Short term survival
• Generally increases energy availability/
  capacity and usage
  – Increase heart rate
  – Increase lung capacity
  – Increase blood flow to muscles
  – Increase blood glucose
• GI tract relaxation
• Increase adrenaline secretion from adrenal medulla
• Vasoconstriction in skin
• Pupil dilation
• Bronchiolar dilation

Question 12

Describe the parasympathetic division.

Answer 12

• ‘Rest and digest’
• Long term survival
• Generally reduces energy availability/ capacity and usage
  – Decrease heart rate
  – Decrease lung capacity
  – Increase blood flow to digestive system
  – Increase fat/glycogen stores

Question 13

What are the differences between the parasympathetic division and sympathetic.

Answer 13

• Where nerves originate
  (leave CNS)
• Differences in
  neurotransmitters and
  receptor subtypes
• Where the ganglia (cell
  bodies) are, ie where 2
  neurons synapse

Question 14

Where is the adrenal gland located?

Answer 14

On top of kidneys

Question 15

Describe the role of the adrenal medulla.

Answer 15

• A major organ of the sympathetic nervous system
• Can cause body-wide release of epinephrine/adrenaline

Question 16

State the physical changes to the body as a result of the parasympathetic system.

Answer 16

• constriction of pupil
• bronchiolar constriction
• increased GI motility + secretion
• inhibitory effects on heart

Question 17

What are the two acetylcholine receptors?

Answer 17

• Nicotinic
• Muscarinic

Question 18

Which receptors mediate the actions of acetylcholine in the ANS?

Answer 18

• Nicotinic receptor
• M1 muscarinic couples to Gq
• M2 muscarinic couples to Gi
• M3 muscarinic coupled to Gq

Question 19

Describe nicotinic receptor.

Answer 19

• Ligand-gated ion channel
• Rapid, short-lived postsynaptic response
• Main receptor on postganglionic ANS neurons

Question 20

Describe M1 muscarinic coupled to Gq.

Answer 20

• Expressed by smooth muscles and glands of the gut
• Smooth muscle contraction, glandular secretion

Question 21

Describe M2 muscarinic coupled to Gi

Answer 21

• Expressed by cardiac muscle of cardiovascular system
• Reduction in heart rate Ach release inhibition

Question 22

Describe M3 muscarinic coupled to Gq

Answer 22

• Expressed by smooth muscle and glands of many parasympathetic targets
• Smooth muscle contraction, glandular secretion

Question 23

Describe adrenoreceptors.

Answer 23

• G-protein coupled (metabotropic)
• 2 types: alpha (α) and beta (β)
• Respond to adrenaline, nor-
  adenaline
• Adrenaline: Diverse actions
  depending on target
• Depending on the downstream
  molecules that they activate

Question 24

What are the five main adrenergic receptor types?

Answer 24

• alpha 1 coupled to Gq
• alpha 2 coupled to Gi
• Beta1 1 coupled to Gs
• beta 2 coupled to Gs
• beta 3 coupled to Gs

Question 25

Describe alpha 1

Answer 25

• activation of phospholipase C
• Contraction of smooth muscles in blood vessels

Question 26

Describe alpha 2

Answer 26

Inhibits adenylate cyclase - reduces cAMP
NE release inhibition

Question 27

Describe beta 1

Answer 27

Actiavtes adenylate cyclase - increases cAMP
- Increases heart rate and contraction strength
- Increases lipolysis in adipose tissue

Question 28

Describe beta 2

Answer 28

Activates adenylate cyclase - increases cAMP
- Relaxation of smooth muscles gut, uterus and bronchi
- Increased glycogen breakdown in liver

Question 29

Describe beta 3

Answer 29

Activates adenylate cyclase - increases cAMP
- Increases lipolysis in adipose tissue

Question 30

Compare sympathetic to parasympathetic.

Answer 30

Sympathetic used acetylcholine and norepinephrine whereas parasympathetic uses acetylcholine

Question 31

Describe the autonomic nervous system

Answer 31

Carries out involuntary actions:
– Vasodilation, bronchodilation, sweating, digestion
– Neurotransmission is via autonomic ganglia
– Transmitter at ganglia is acetylcholine