ANS

Question 1

Where is the ANS in the NS

Answer 1

part of the PNS

Question 2

Place of the ANS in the structural organization of the nervous system

Answer 2

• Effectors:
• Cardiac muscle
• Smooth muscle
• Glands

Question 3

What neuron chain does ANS use

Answer 3

2 neuron chain

Question 4

Where is cell body of preganglionic neuron and where do they synapse

Answer 4

Brainstem or spinal cord and synapse in post-ganglionic cell body outside of the CNS

Question 5

Primary neurotransmitters

Answer 5

acetylcholine (ACh) and norepinephrine (NE).

Question 6

T or F: most effectors are influenced by both divisions simultaneously

Answer 6

T

Question 7

Sympathetic and parasympathetic nervous systems are distinguished by

Answer 7

• their unique sites of origin.
• the relative length of their fibres.
• the location of their ganglia.
• Key anatomical differences between ANS divisions.
• Anatomical and Physiological Differences between the Parasympathetic and

Question 8

Name sacral nerve roots of parasympathetic (craniosacral)

Answer 8

• Oculomotor nerve (III)
• Facial nerve (VII)
• Glossopharyngeal nerve (IX)
• Vagus nerve (X)
• Vagus nerves accounts for approximately 90% of all preganglionic parasympathetic fibres
• Sacral outflow: Located in the lateral gray matter of spinal cord segments S2-4.
• Parasympathetic nerves branch and form the splanchnic nerves.
• These innervate the distal half of the large intestine, urinary bladder, ureters, and reproductive organs.

Question 9

in the sympathetic (thoracolumnar) where do the sympathetic fibers arise at

Answer 9

between T1-L2
* The cell bodies of these neurons are located in the lateral horns of the gray matter in spinal cord.
* The paravertebral chain ganglia flanks each side of the vertebral column.

Question 10

How many chain ganglia are there

Answer 10

There are 23 chain ganglia (3 cervical, 11 thoracic, 4 lumbar, 4 sacral, and 1 coccygeal).

Question 11

What happens when a preganglionic nerve reaches a chain ganglion

Answer 11

1 of 3 things can happen:
* It can synapse at the same level it exits.
* It can ascend or descend to synapse at another level.
* It can bypass the chain ganglion and synapse at a distant collateral ganglion.

Question 12

T or F: Upon stimulation, medullary cells secrete norepinephrine and epinephrine into blood

Answer 12

T

Question 13

Describe Ach and Ne

Answer 13

• Acetylcholine (ACh) and norepinephrine (NE) are the major neurotransmitters within the ANS
• ACh releasing fibres are “cholinergic”
• NE releasing fibres are “adrenergic”
• The different types of receptors for ACh and NE determine whether they will be excitatory or inhibitory.

Question 14

T or F: All ACh receptors are nicotinic

Answer 14

F, All ACh receptors are either nicotinic or muscarinic

Question 15

Where are nicotinic and muscanaric receptors found

Answer 15

• Nicotinic (excitatory) receptors are found on:
• All post-ganglionic neurons (sympathetic and parasympathetic)
• The hormone producing cells of the adrenal medulla
• At the motor end plates of skeletal muscle.
• Muscarinic (inhibitory or excitatory) are found:
• On all parasympathetic target organs
• Some sympathetic targets (e.g. sweat glands, some blood vessels

Question 16

Parasympathetic inhibition & excitation example:

Answer 16

• Inhibitory example: binding of ACh to muscarinic receptor on cardiac muscle slows heart rate
• Excitatory example: binding of ACh to muscarinic receptors of smooth muscle increase GI tract motility.

Question 17

2 classes of adregenic recewptors

Answer 17

alpha and beta receptors
* Organs that respond to NE (or epinephrine – “E”) have A and B receptor
* B1 and B3 receptors are excitatory (e.g. increased heart rate)
- B2 receptors are mostly inhibitory (e.g. dilation of blood vessels and bronchioles).

Question 18

what is *Sympathetic tone (vasomotor tone):

Answer 18

continual state of partial constriction of blood vessels

Question 19

what is Parasympathetic tone:

Answer 19

• It is maintained in the heart and smooth muscles of digestive and urinary tracts
• This activity slows the heart and controls normal activity of the digestive and urinary tracts.

Question 20

Roles for SNS

Answer 20

• Thermoregulation in response to temperature change on skin
• Release of renin from kidneys = increased blood pressure
• Metabolic effects (increased glucose and fats available for utilization via cortisol release)
• Adrenal medulla hormones causes stronger and faster skeletal muscle contractions
• Note: All of these play a role in survival.

Question 21

ratio of pre to post ganglion in PNS

Answer 21

ratio of about 1:3 pre to post ganglionic fibres at most
* These fibres release ACh at their effector target that is quickly hydrolyzed by acetylcholinesterase
* Result: brief and local control over effectors.

Question 22

ratio of pre to post ganglion in SNS

Answer 22

high ratio of pre to postganglionic receptors (approximately 1:10).

Question 23

why do effects of SNS last longer than PNS

Answer 23

The effects of the sympathetic system last longer than the parasympathetic system for 3 reasons:
* NE is inactivated more slowly than ACh
* NE acts through second messengers while ACh acts directly via ligand gated ion channels
* NE and E are released in the blood where they are active until they are broken down by liver

Question 24

What is main intergrator of ANS

Answer 24

Hypothalamus

Question 25

T or F: Spinal cord controls defecation and micturition but are subject to conscious override

Answer 25

T

Question 26

What does the midbrain control

Answer 26

Muscles of pupil and lens

Question 27

What does medulla regulate

Answer 27

HR, BV diameter