2.2 Central and Peripheral Nervous system

Question 1

Glial cell

Answer 1

Non-neuronal support cell in the CNS

Question 2

Oligodendrocytes

Answer 2

Subtype of glial cell, produces myelin throughout the CNS,wrap multiple axons

Question 3

Microglia

Answer 3

Rove body looking for things to engulf, digest

Question 4

Astrocyte

Answer 4

Glue that holds everything together, provide metabolic and structural support… Protects neurons by regulating what passes between capillaries and neurons

Question 5

Ependymal cells

Answer 5

Secrete cerebrospinal fluid that is in hollow spaces of brain

Question 6

What makes up the blood brain barrier?

Answer 6

Astrocyte foot processes and endothelial cells that line blood vessels in brain

Question 7

How do lipid soluble substances get across the BBB?

Answer 7

Still by diffusion

O2, CO2, nicotine, alcohol, steroids

Question 8

How do small polar substances move through the BBB?

Answer 8

Transport proteins

amino acids, glucose, etc

Question 9

What kind of metabolic rate does the brain have?

Answer 9

Extremely high!

Question 10

What percent of cardiac output does the brain receive?

Answer 10

15-20% even though the brain only makes up 2% of body weight

Question 11

Why is the brain so dependent upon constant supply of oxygen and glucose and removal of carbon dioxide?

Answer 11

Resting membrane potential!

Question 12

How soon does fainting occur if blood flow or blood glucose drops?

Answer 12

Within seconds

Question 13

How soon does irreversible brain damage occur if blood flow or blood glucose drops?

Answer 13

Within 4 minutes, takes so long because we have a reserve of oxygen in RBCs to draw from

Question 14

Meninges

Answer 14

Connective tissue membranes surrounding the CNS

Question 15

Dura mater

Answer 15

Outer tough layer

Question 16

Arachnoid mater

Answer 16

Middle, spidery weblike tissue

Question 17

Pia mater

Answer 17

Thin, bound tightly to brain surface

Question 18

Subdural space

Answer 18

Between dura and arachnoid, contains interstitial serous fluid, helps cushion

Question 19

Subarachnoid space

Answer 19

Between arachnoid and pia mater, contains CSF (most spacious)

Question 20

Meningitis

Answer 20

Inflammation of connective tissue layers

Question 21

Cerebrospinal fluid in comparison to blood plasma

Answer 21

Fewer ions and less protein

Question 22

CSF

Answer 22

~150mL in brain / spine

Bathes brain and spinal cord (in subarachnoid space)

Question 23

Functions of CSF

Answer 23

Buoyancy, protection, stabilizes nutrient delivery

Question 24

Where is CSF secreted?

Answer 24

By ependymal cells in choroid plexuses located in ventricles (fluid filled cavities containing CSF)

Question 25

Anatomical segments of spinal cord

Answer 25

Cervical, thoracic, lumbar, sacral

Question 26

How many bilateral pairs of spinal nerves extending bilaterally to Peripheral nervous system are there?

Answer 26

31 - 8 cervical - 12 thoracic - 5 lumbar - 5 sacral - 1 coccygeal

Question 27

What are the two "bulges" in diameter of the spinal cord?

Answer 27

-Cervical enlargement (supplies upper limbs) -Lumbar enlargement (supplies lower limbs)

Question 28

Does an epidural enter the CSF?

Answer 28

NO, goes only into the epidural space (above dura mater), do not want to go through dura mater or else you could numb the entire body

Question 29

White matter

Answer 29

Myelinated axons forming nerve tracts

Question 30

What are tracts?

Answer 30

Bundles of related axons in the CNS (nerves in PNS)

Question 31

Gray matter

Answer 31

Neuron cell bodies & dendrites (no myelin) forms a distinct H or butterfly shape

Question 32

White matter components

Answer 32

Dorsal column Vertebral column Lateral column

Question 33

Gray matter components

Answer 33

Posterior horn Lateral horn Anterior horn

Question 34

Posterior horn and the dorsal root ganglion are composed of...

Answer 34

Cell bodies of SENSORY neurons, unmyelinated regions so are gray matter

Question 35

Dorsal roots

Answer 35

Bundles of myelinated axons (white matter) leaving the sensory neuron cell bodies in PH or DRG

Question 36

The afferent sensory axons synapse in...

Answer 36

Posterior horn onto. .. 1. ) Interneurons (lead directly to motor tract) 2. )Ascending sensory tracts in spinal cord

Question 37

Anterior horns

Answer 37

Contain cell bodies of somatic MOTOR neurons, descending tracts

Question 38

Lateral horns

Answer 38

Contain cell bodies of autonomic neurons

Question 39

Ventral roots

Answer 39

Convergence of axons carrying EFFERENT (outgoing) action potentials from both the motor and autonomic neurons-these APs originate in the brain and are carried on descending tracts

Question 40

Dermatomes

Answer 40

A distinct area of skin innervated by the sensory nerves that form the pair of bilateral spinal nerves

Question 41

Which viral disease is seen in specific dermatomes?

Answer 41

Shingles

Question 42

Why are spinal cord injuries so permanent?

Answer 42

There is a disconnect between PNS and CNS and PNS nerves can't grow back and reconnect to CNS tracts, wiring done only during embryonic stage

Question 43

How stable are the neurons of the CNS?

Answer 43

They are on the edge of life, any disruption to blood supply can kill them

Question 44

Reflex arcs

Answer 44

Simplest functional unit of nervous system | -Hard-wired, involuntary responses

Question 45

SAME

Answer 45

Sensory afferent motor efferent

Question 46

What do withdrawal reflexed typically involve?

Answer 46

Excitatory interneurons and inhibitory interneurons

Question 47

Reciprocal innervation

Answer 47

Interneuron wiring pattern that causes necessary -Extensor muscle relaxation (reciprocal inhibition) -Flexor muscle contraction (reciprocal activation)

Question 48

Withdrawal reflex in leg

Answer 48

Leads to ipsilateral flexion, , you activate the effector that moves the affected limb away from the injury

Question 49

Crossed extensor reflex

Answer 49

A withdrawal reflex in one lower limb causes extension of the opposite lower limb

Question 50

Stretch receptors

Answer 50

Located in muscle spindles and tendon organs, cause the reflexes that we test

Question 51

Intrafusal muscle fibers

Answer 51

Within a muscle spindle; info on muscle position and coordination(finesse)

Question 52

Extrafusal muscle fibers

Answer 52

Outside spindle, mediate muscle contraction, muscle power

Question 53

Golgi tendon organ

Answer 53

Afferent sensory innervation in tendons (muscle to bone) provide feedback on tension

Question 54

Stretch myotactic reflex functions

Answer 54

Regulates muscle length, coordinates muscle recruitment when stretching occurs, protects from overstitching or pulling muscles

Question 55

Golgi tendon reflex function

Answer 55

Regulates muscle tension, prevents tendon tears due to excessive muscle contraction

Question 56

Golgi tendon relfex

Answer 56

Antagonistic muscles (hamstring) contracts in response to other muscle stress (quad) ---> RECIPROCAL INHIBITION