2.2 Central and Peripheral Nervous system Flashcards Preview

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Flashcards in 2.2 Central and Peripheral Nervous system Deck (56):
1

Glial cell

Non-neuronal support cell in the CNS

2

Oligodendrocytes

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

3

Microglia

Rove body looking for things to engulf, digest

4

Astrocyte

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

5

Ependymal cells

Secrete cerebrospinal fluid that is in hollow spaces of brain

6

What makes up the blood brain barrier?

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

7

How do lipid soluble substances get across the BBB?

Still by diffusion
(O2, CO2, nicotine, alcohol, steroids)

8

How do small polar substances move through the BBB?

Transport proteins
(amino acids, glucose, etc)

9

What kind of metabolic rate does the brain have?

Extremely high!

10

What percent of cardiac output does the brain receive?

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

11

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

Resting membrane potential!

12

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

Within seconds

13

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

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

14

Meninges

Connective tissue membranes surrounding the CNS

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Dura mater

Outer tough layer

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Arachnoid mater

Middle, spidery weblike tissue

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Pia mater

Thin, bound tightly to brain surface

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Subdural space

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

19

Subarachnoid space

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

20

Meningitis

Inflammation of connective tissue layers

21

Cerebrospinal fluid in comparison to blood plasma

Fewer ions and less protein

22

CSF

~150mL in brain / spine
Bathes brain and spinal cord (in subarachnoid space)

23

Functions of CSF

Buoyancy, protection, stabilizes nutrient delivery

24

Where is CSF secreted?

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

25

Anatomical segments of spinal cord

Cervical, thoracic, lumbar, sacral

26

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

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

27

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

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

28

Does an epidural enter the CSF?

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

29

White matter

Myelinated axons forming nerve tracts

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What are tracts?

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

31

Gray matter

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

32

White matter components

Dorsal column
Vertebral column
Lateral column

33

Gray matter components

Posterior horn
Lateral horn
Anterior horn

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

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

35

Dorsal roots

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

36

The afferent sensory axons synapse in...

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

37

Anterior horns

Contain cell bodies of somatic MOTOR neurons, descending tracts

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Lateral horns

Contain cell bodies of autonomic neurons

39

Ventral roots

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

40

Dermatomes

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

41

Which viral disease is seen in specific dermatomes?

Shingles

42

Why are spinal cord injuries so permanent?

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

43

How stable are the neurons of the CNS?

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

44

Reflex arcs

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

45

SAME

Sensory afferent motor efferent

46

What do withdrawal reflexed typically involve?

Excitatory interneurons and inhibitory interneurons

47

Reciprocal innervation

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

48

Withdrawal reflex in leg

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

49

Crossed extensor reflex

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

50

Stretch receptors

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

51

Intrafusal muscle fibers

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

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Extrafusal muscle fibers

Outside spindle, mediate muscle contraction, muscle power

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Golgi tendon organ

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

54

Stretch myotactic reflex functions

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

55

Golgi tendon reflex function

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

56

Golgi tendon relfex

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