Presentation 18: Nervous system overview, PNS and ANS

Question 1

Autonomic Nervous System (ANS) Function

Answer 1

visceral motor system (non-voluntary control) ex. controls heart muscles

Question 2

How does the ANS differ from the PNS and CNS?

Answer 2

Composed of at least 2 neurons in a series that carry signals to visceral effectors (i.e. cardiac and smooth muscles, glands, etc,)
- preganglionic neuron
- postganglionic neuron

Question 3

Preganglionic neuron

Answer 3

Neuron that’s part of the ANS
- stretches from CNS to autonomic ganglion
- short in sympathetic system
- long in parasympathetic system

Question 4

Post ganglionic neuron

Answer 4

Neuron that’s part of the ANS
- stretches from autonomic ganglion cell body to effector
- long in sympathetic system
- short in parasympathetic system

Question 5

How is the ANS categorized in Amniota

Answer 5

The Sympathetic (aka thoracolumbar) and Parasympathetic (craniosacral) systems

Question 6

Sympathetic system

Answer 6

Part of the ANS in amniota (thoracolumbar)
- exits CNS w/ spinal nerves but diverge @ visceral ramus
- adrenergic system (neurotransmitters = adrenalin + noradrenalin)
- synapse occurs in synaptic trunk (collection of ganglia)

Question 7

Parasympathetic system

Answer 7

Part of the ANS in amniota (craniosacral)
- fibers exit CNS w/ cranial nerves 3,4,9,10, + 11
- neurotransmitter = acetylcholine

Question 8

What are the functions of the nervous system?

Answer 8

• allows body to respond to changes in external environment
• regulates internal environment
• store information

Question 9

What are the components of the Nervous System?

Answer 9

• Central Nervous System (CNS) = brain and spinal cord
• Peripheral Nervous System (PNS) = cranial, spinal, and autonomic nerves
• Neurons = soma and 1 or more processes (an efferent axon and many afferent dendrites)

Question 10

What are bundles of somas and processes called in the CNS vs the PNS?

Answer 10

Bundles of somas:
- CNS = Nucleus/Center/Olive
- PNS = Ganglion

Bundles of processes:
- CNS = tracts
- PNS = nerves

Question 11

Neuroglia

Answer 11

Cells that support, nourish, and insulate neurons
- include microglia, astrocytes, oligodendroglia/schwann cells, and ependymal cells

Question 12

Ependymal cells

Answer 12

Line central canal of CNS (ependymus)

Question 13

Microglia

Answer 13

Engulf and destroy foreign material/bacterial (phage cells)

Question 14

Astrocytes

Answer 14

pass nutrients and maintain normal physiology

Question 15

Oligodendroglia

Answer 15

In the CNS - insulate axons by producing myelin sheath which surround the axon alongside neurolimma which form white (more myelin) and grey (less myelin) fibers

Question 16

Schwann cells

Answer 16

In the PNS - insulate axons by producing myelin sheath which surround the axon alongside neurolimma which form white (more myelin) and grey (less myelin) fibers

Question 17

What are the Meninges

Answer 17

Connective tissue that surrounds and protects the brain and spinal cord from rubbing against bone
- Fishes have 1 layer (menix primitiva)
- Non mammalian vertebrates have 2 (dura mater and lepto meninx)
- mammals have 3 (dural mater, arachnoid matter, and pia mater)

Question 18

What are the different layers of the Meningesd in fish, non-mammalian vertebrates, and mammals?

Answer 18

Fish: Menix primitiva

Non-mammals: 2 layers
- Dura mater (outer layer in contact w/ bone)
- Lepto meninx (inner vascular layer)

Mammals: 3 layers (lepto meninx divides)
- Dura mater (outer layer in contact w/ bone)
- Arachnoid mater (middle layer)
- Pia mater (innermost vascular layer)

Question 19

Spinal Nerves

Answer 19

Metameric (repeated unit arranged sequentially) w/ dorsal and ventral root that attatch to nerves of spinal cord
- fuse distally and then form ventral, dorsal, and visceral rami

Question 20

Describe the Rami of the spinal nerves

Answer 20

Ventral Ramus: Hypaxial muscles - coordinates and organizes limb movement through plexus (brachial i.e. anterior limbs and lumbosacral i.e. post limbs)

Dorsal: Epaxial Muscles

Visceral: Goes to organs and autonomous NS

Question 21

How are PNS nerves categorized?

Answer 21

-Somatic (voluntary) vs Visceral (involuntary)
AND
-Sensory (afferent) vs Motor (efferent)

Question 22

Cranial nerve diversity

Answer 22

at least 10 pairs in all vertebrates, 12 in amniota along with cranial nerve 0 (detects pheromones)
- nerves 11 and 12 are homologous to non-amniotes, but only present as descrete nerves in amniotes
- 11 = part of 10 and occitospinal series
- 12 = rest of occitospinal series

Question 23

Describe the main functions of the cranial nerves

Answer 23

Nerves 1, 2, + 8 = sensory nerves
- 2 + 8 = somatic sensory for optic and otic sense organs = optic/auditory nerves
- 1 - visceral sensory nerve epithelium of olfactory tract = olfactory nerve

Nerves 3, 4 + 6 = somatic motor nerves
- innervate eye muscles, similar to spinal nerves but no dorsal (sensory) root

Nerves 5, 7, 9, + 10 = mixed function
- Usually assoc. w/ gill arches
- 5 = mandibular arch, 7 = hyoid arch, 9 = 1st branchial arch, 10 = remaning brachial arches