Body Plan 09: Peripheral Nervous System

Question 1

Neurons

Answer 1

Nervous tissue

Question 2

What are some characteristics of neurons

Answer 2

They are excitable and can generate action potentials. They have a large central nucleus and are metabolically very active

Question 3

Synapses

Answer 3

Small cavities between neurons

Question 4

How do neurons transmit information to other neurons?

Answer 4

They release neurotransmitters into synapses which diffuse into the other neurons

Question 5

Synaptic vesicles

Answer 5

Vesicles on the neurons that release neurotransmitters

Question 6

Central Nervous System

Answer 6

The brain and spinal cord

Question 7

Peripheral Nervous System

Answer 7

All of the nervous system that is not in the CNS

Question 8

Microglia

Answer 8

Cells found only in the CNS. They are macrophages and arise in the yolk sac

Question 9

Macroglia

Answer 9

Cells found only in the CNS. They are of two types: Oligodendrocytes and Astrocytes

Question 10

Oligodendrocytes

Answer 10

One of the macroglia of the CNS. They form myelin around multiple cells each of the CNS and support them

Question 11

Astrocytes

Answer 11

One of the macroglia of the CNS. They are the main foundation of the blood-brain barrier

Question 12

Schwann Cells

Answer 12

Cells found only in the PNS. They form myelin around one cell each

Question 13

Satellite Cells

Answer 13

Cells found only in the PNS. They surround cell bodies in ganglia

Question 14

Myelin

Answer 14

Multiple layers of fused plasma membranes around a neuron that serves to insulate the neuron and speed up the action potential

Question 15

Myelinated neurons

Answer 15

Neurons that have had glial cells injected into them and are protected by plasma membranes forming the myelin

Question 16

Nonmyelinated neurons

Answer 16

Neurons that have had glial cells injected into them, bubbling around in the cytoplasm and shrinking in. NOTE: there are still glial cells involved

Question 17

Nodes of Ranvier

Answer 17

Short segments of unmyelinated axon that serves to generate and revitalize action potentials

Question 18

The Blood-Brain Barrier

Answer 18

A combination of astrocytes and tight junctions in the vascular endothelia that regulates the passage of proteins from the blood vessels into the brain

Question 19

How many nerves are in the PNS?

Answer 19

43 - 12 cranial and 31 spinal

Question 20

How many cranial nerves are in the PNS?

Answer 20

12

Question 21

How many spinal nerves are in the PNS?

Answer 21

31

Question 22

What are the five segments of the spinal cord?

Answer 22

Cervical, Thoracic, Lumbar, Sarcal, Coccygeal

Question 23

How many sections are in each of the segments of the spinal cord

Answer 23

8 C, 12 T, 5 L, 5 S, 1 coccygeal

Question 24

Gray mater

Answer 24

CNS matter consisting of cell bodies

Question 25

White mater

Answer 25

CNS matter not consisting of cell bodies

Question 26

Dorsal horn

Answer 26

The section of the gray mater that points dorsally, where impulses enter the CNS

Question 27

Lateral horn

Answer 27

The section of the gray mater that points laterally and houses the PNS cell bodies. They only exist in T1-L2 (sympathetic) and S2-S5 (parasympathetic)

Question 28

Ventral horn

Answer 28

The section of the gray matter that points ventrally, where impulses leave the CNS

Question 29

Nerves

Answer 29

Bundles of axon and dendrites in the PNS

Question 30

Epineurium

Answer 30

outermost connective tissue sheath, loose connective tissue, fibroblasts and collages

Question 31

Perineurium

Answer 31

multiple layers of flattened polygonal cells and collagen; tight junctions; a metabolically active diffusion barrier

Question 32

Endoneurium

Answer 32

intra-fascicular connective tissue, fibrous matrix of reticular (Type III collagen) fibers, endoneurial fluid, immune cells, Schwann cell-axon units

Question 33

Can a neuron be both sensory and motor?

Answer 33

No, only one or the other

Question 34

Can a nerve be both sensory and motor?

Answer 34

Yes, but each individual neuron can only be one or the other

Question 35

Fascile

Answer 35

A fiber of neuron cells surrounded by the perineurium

Question 36

How are peripheral nerves histologically identifiable?

Answer 36

Nodes of Ranvier, zig-zag shape, foamy appearance of myelin

Question 37

Ganglia

Answer 37

Groups of cell bodies in the PNS

Question 38

Neural Nuclei

Answer 38

Groups of cell bodies in the CNS. Analogous to ganglia

Question 39

What types of cell bodies can ganglia contain?

Answer 39

Either only visceral motor, or a combination of visceral sensory and somatosensory

Question 40

What are the three major groups of ganglia?

Answer 40

Dorsal root ganglia, Paravertebral ganglia, preaortic ganglia

Question 41

Dorsal root ganglion

Answer 41

A sensory ganglion also known as the spinal ganglion that comes off of the dorsal horn

Question 42

What is the main histological difference between parasympathetic and sympathetic ganglia?

Answer 42

Sympathetic ganglia have lipofuschin granules, while parasympathetic ganglia

Question 43

Afferent

Answer 43

Carrying impulses towards the CNS

Question 44

Efferent

Answer 44

Carrying impulses away from CNS

Question 45

Nonsensory afferent

Answer 45

Not perceived, does not reach the cortex. Examples include CO2 levels and blood pressure

Question 46

Sensory afferet

Answer 46

Perceived (we feel it). It can be broken down to touch, vibration, proprioception; and pain, temperature

Question 47

Pacinian Corpuscles

Answer 47

The sensory system of the skin. Includes Meissner’s corpuscles, Merkel cells and free endings

Question 48

Somatic nervous system

Answer 48

Goes to skeletal muscles. No second cell bodies; they synapse directly onto skeletal muscle

Question 49

Visceral nervous system

Answer 49

Goes to smooth and cardiac muscles ("autonomous"). Divided into sympathetic and parasympathetic

Question 50

Somatic vs visceral NS: which one is more precise temporally? Spatially?

Answer 50

Somatic is more precises in both, both afferent and efferent

Question 51

Why is the visceral nervous system imprecise spatially?

Answer 51

One neuron synapses on many muscles

Question 52

Enteric Nervous System

Answer 52

The nervous system of the gut that controls smooth muscle, blood vessels, and secretion by mucosa

Question 53

Where are the somatic structures derived from?

Answer 53

From the somites, somatic layer of lateral mesoderm, and neural crest

Question 54

Where are the visceral structures derived from?

Answer 54

From the splanchnic layer of the lateral mesoderm, intermediate mesoderm, and neural crest

Question 55

Where are sympathetic cell bodies located in the CNS?

Answer 55

Lateral horn of T1 through L2

Question 56

Where are parasympathetic cell bodies located in the CNS?

Answer 56

Brain and lateral horn of S2, S3, S4

Question 57

Where do sympathetic cell bodies leave the CNS?

Answer 57

Ventral roots of T1 through L2

Question 58

Where do parasympathetic cell bodies leave the CNS

Answer 58

Cranial nerves and ventral roots of S2, S3, S4

Question 59

Where is the 2nd cell body of sympathetic cells located?

Answer 59

Ganglia not associated with the target organ

Question 60

Where is the 2nd cell body of parasympathetic cells located?

Answer 60

Ganglia associated with the target organ

Question 61

What neurotransmitter is used for the somatic nervous system?

Answer 61

ACh

Question 62

What is the first order neurotransmitter used for the sympathetic and parasympathetic nervous systems?

Answer 62

Both use ACh

Question 63

What is the second order neurotransmitter used for the sympathetic system?

Answer 63

Noradrenaline for adrenergic neurons and ACh for sweat clands

Question 64

What is the second order neurotransmitter used for the parasympathetic system?

Answer 64

ACh

Question 65

What three structures to sympathetic nerves go to for temperature control?

Answer 65

Vascular smooth muscle, errcrine sweat glands, Arrector pili muscles