ANS

Question 1

Autonomic →

Answer 1

autonomous, carries out its functions involuntarily

Question 2

Functions of the ANS:

Answer 2

– Maintenance of homeostasis
(maintain a constant internal env.)

– Activation of emergency mechanisms (eg. Response to stress)

– Housekeeping functions (eg. Digestion)

Question 3

Afferent neurons →

Answer 3

relay sensory information to the CNS

Question 4

Efferent neurons →

Answer 4

relay motor commands from the CNS to target tissues

Question 5

Cranial Nerves

Answer 5

• 12 pairs of cranial nerves
• 31 pairs of spinal nerves that connect with the spinal cord
• Attached at the brain (Including brainstem)
• Cranial nerve → contains both afferent and efferent fibres
• Spinal nerve → contains both afferent and efferent fibers

Question 6

Somatic nervous system: efferent nerve of the PNS

Answer 6

Single neuron, single target, single synapse, always excitatory

NT: ACh

• myelinated

Question 7

Autonomic nervous system: efferent nerve of the PNS

Answer 7

• 2 neuron chain connected by a synapse (Ganglion), multiple targets,
excitatory/inhibitory effects

• Ganglion → cluster of neuron cell bodies outside the CNS

NT: ACh, NE, EP

• myelinated preganglionic, unmeylinated postganglionic

Question 8

Sympathetic trunk/chain →

Answer 8

one of paired chains of interconnected sympathetic ganglia that lie on either side of the vertebral column
(Also called paravertebral ganglion)

Question 9

Sympathetic trunk →

Answer 9

paravertebral ganglion

Question 10

Collateral ganglion →

Answer 10

prevertebral ganglion

– Sympathetic ganglia located in front of
the vertebral column, outside the
sympathetic chain, close to the viscera and arteries; innervation of abdominal and pelvic viscera

– Celiac ganglion, superior mesenteric, inferior mesenteric ganglion

Question 11

Sympathetic division

Neural pathways:

Answer 11

1. Synapse immediately with a postganglionic neuron in sympathetic ganglion
2. Travel up or down the chain and synapse in ganglia at other levels
3. Pass through chain without synapsing, continue to collateral ganglion as splanchnic nerve

Question 12

Communicating rami in sympathetic pathway

Answer 12

two branches which connect a paravertebral ganglion to

a spinal nerve; include white and gray rami

Question 13

White rami →

Answer 13

branch by which a myelinated preganglionic fiber leaves the spinal nerve and enters a sympathetic ganglion

Question 14

Gray rami →

Answer 14

branch by which unmyelinated postganglionic fibers leave the ganglion to re-enter the spinal nerve

Question 15

The Adrenal Medulla

Answer 15

• Outer adrenal cortex and inner
Adrenal cortex adrenal medulla

• Innervated by sympathetic preganglionic neurons

• release EP and NE

– Blood → hormones
– Broken down in liver → prolongs effects on tissues

Question 16

Parasympathetic Nervous System: Craniosacral

Answer 16

• Originate in brainstem and sacral regions (Cranial nerves III,VII,IX,X and S2-S4)

– Supply the visceral structures in the head by the oculomotor (III), facial (VII), glossopharyngeal (IX) nerves and the thorax and upper abdomen by the Vagus (X) nerve

Question 17

Parasympathetic pathway

• Terminal ganglion →

Answer 17

a parasympathetic ganglion situated on or close to an innervated organ, the site where preganglionic nerve fibers terminate

Question 18

Dual Autonomic Innervation

• Autonomic tone →

Answer 18

background level of activity maintained by both sympathetic and parasympathetic divisions; balance between
sympathetic tone and parasympathetic tone shifts in accordance with the body’s needs

Question 19

Dual Autonomic Innervation

Activated reciprocally →

Answer 19

the activity of one system will increase

and the activity of the other will decrease

Question 20

• Sympathetic dominates during_________

* Parasympathetic dominates during _________

Answer 20

“fight or flight”

“rest or digest”

Question 21

Dual innervation →

Answer 21

(Most) body organs and tissues receive both sympathetic and parasympathetic innervation

Question 22

Exceptions to dual innervation:

Answer 22

Adrenal medulla, blood vessels (Most), sweat glands receive sympathetic only

Question 23

Dual Autonomic Innervation

Antagonistic or cooperative effects:

Answer 23

• Antagonistic eg.

• Sympathetic → ↓ GI motility; ↑ heart rate
• Parasympathetic → ↑ GI motility; ↓ heart rate

• Cooperative eg. Salivary glands → - sympathetic and parasympathetic innervation change the type and volume of
saliva produced

Question 24

Varicosity →

Answer 24

chains of swellings along the branches of a postganglionic fiber; contain synaptic vesicles which release NT

– Neurotransmitter may affect many cells simultaneously

– Sympathetic or parasympathetic postganglionic fibers

Question 25

Acetylcholine

Answer 25

– All autonomic ganglia (parasympathetic and sympathetic) – Parasympathetic postganglionic endings – A few sympathetic postganglionic endings (eg. Sweat glands, blood vessels of skeletal muscle)

Question 26

Norepinephrine

Answer 26

– Most sympathetic postganglionic endings – Released from adrenal medulla (also epinephrine; hormones)

Question 27

Cholinergic receptors →

Answer 27

bind ACh – Nicotinic and muscarinic receptors

Question 28

Nicotinic receptors

Answer 28

* NM → found in skeletal muscle * NN→ found on the postsynaptic cell bodies in all autonomic ganglia (sympathetic and parasympathetic) * Ionotropic

Question 29

Nicotinic receptors • Ionotropic →

Answer 29

receptor is also a ligand-gated ion channel – Binding of ACh opens a cation channel allowing Na+ and K+ through; larger movement of Na+ causes rapid depolarization of postganglionic neurons – Produces EPSP (Excitatory response)

Question 30

Receptors - N-AChR → - M-AChR → - Adrenergic R →

Answer 30

- N-AChR → Nicotinic Acetylcholine Receptor - M-AChR → Muscarinic Acetylcholine Receptor - Adrenergic R → Norepinephrine/epinephrine Receptor

Question 31

Cholinergic receptors →

Answer 31

bind ACh | – Nicotinic and muscarinic receptors

Question 32

Muscarinic

Answer 32

* M1, M2, M3, M4, M5 * Found on effector cell membranes (Smooth muscle, cardiac muscle, glands) • Metabotropic – Binding of ACh causes excitation or inhibition of target through G-protein coupled mechanism

Question 33

Adrenergic receptors →

Answer 33

bind NE/E – α (α1,α2) and β (β1,β 2,β3) receptors – Found on effector cell membranes (Smooth muscle, cardiac muscle, glands) – Metabotropic • Binding of NE/E causes excitation or inhibition of target through G-protein coupled mechanism

Question 34

Muscarinic and Adrenergic Receptors

Answer 34

* Binding of ACh to muscarinic receptors and NE/E to adrenergic receptors produces response through G-protein coupled mechanism * eg. In smooth muscle etc.

Question 35

Convergence →

Answer 35

numerous presynaptic neurons form synapses with a single postsynaptic neuron (Coming together)

Question 36

Divergence →

Answer 36

small number of presynaptic neurons form synapses with a large number of postsynapatic neurons (Spreading out)

Question 37

Sympathetic nervous system exhibits a greater degree of

Answer 37

divergence than the parasympathetic system

Question 38

– Sympathetic → | – Parasympathetic →

Answer 38

– Sympathetic → diffuse | – Parasympathetic → specific

Question 39

Spinal cord →

Answer 39

integrates autonomic reflexes (Urination, defecation); brain is able to influence these reflexes

Question 40

Medulla oblongata (Brainstem) →

Answer 40

contains major ANS reflex centers | centers for cardiovascular, respiratory, digestive activity

Question 41

Hypothalamus →

Answer 41

integration and command center for autonomic functions; temperature regulation