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Neuro > CH 1: Intro to NS > Flashcards

CH 1: Intro to NS Flashcards

1
Q

neuron (nerve cell)

A

constitutes the primary functional and anatomic unit of the NS

all consist of a cell body containing a nucleus and surrounding cytoplasm

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2
Q

dendrites

A

consist of afferent neuronal processes with branches that receive signals.

usually the signals consist of chemicals acting as NEUROTRANSMITTERS that interact with specific molecular receptors

these signals transiently alter the electrochemical gradient across the membrane of the dendritic process, and this transient change moves along the dendrites

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3
Q

axon

A

on a nerve cell
consists of a single fiber extending to other parts of the NS or to a muscle or gland

“axon” aplies to a fiber that conducts impulses (actively propagated electrochemical changes called ACTION POTENTIALS away from the dendrites

EFFERENT fiber or process

at its end, branches of the axon make synaptic contact with other neurons

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4
Q

nerve cell bodies usually cluster together

A

outside the brain and SC= ganglia of the PNS

within the brain and SC (CNS)= nuclei

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5
Q

cerebral and cerebellar cortex are made up of?

A

the layers (laminae) of nerve cell bodies on the surface of the cerebrum and cerebellum

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6
Q

gray matter

A

regions of the brain and SC that contain aggregations of nerve cell bodies

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7
Q

white matter

A

areas of the brain and SC that consist primarily of myelinated axons

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8
Q

tract=

A

in the CNS
groups of axons that have a common origin (cell bodies in the same nucleus) and a common destination (axonal endings in the same area of gray matter)

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9
Q

specific bundles of nerve fibers in the PNS=

A

nerve, nerve root, nerve trunk, nerve cord, and ramus

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10
Q

3 types of neuroglia/glial cells in the CNS=

A

= NEUROGLIA or GLIAL CELLS

1- astrocytes

2- oligodendrocytes

3- microglia

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11
Q

oligodendrocytes

A

form and maintainthe myelin sheaths of axons in the CNS

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12
Q

astrocytes

A

contribute in a variety of important ways to the metabolism of the CNS:

1: can’t develop APs but are highly permeable to potassium (K+) ions and become depolarized if the extracellular concentration of K+ increases.
2: take up extracellular K+ during intense neuronal activity and thereby buffer K+ activity
3: take up and store neurotransmitters- regulate extracellular concentrations of neurotransmitters
4: transfer metabolites from capillaries to the extracellular space

5: sensitive to many different insults to CNS tissue: may respond to injury with cytoplasmic swelling, accumulation of glycogen, fibrillar proliferation with the cytoplasm, cell multiplication or a combo
- they frequently have a permanent scar or plaque after destruction of neuronal elements have occurred

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13
Q

microglia

A

phagocytic cells that form part of the NS’s defense against infection and injury

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14
Q

nonneural cells=

A

neuroglia or glial cells

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15
Q

glial cells of the PNS

A

Schwann cells

satellite cells

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16
Q

Schwann cells

A

produce myelin

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17
Q

satellite cells

A

found in ganglia associated with the peripheral nerves

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18
Q

PNS is composed of..

A

12 pairs of cranial nerves
31 pairs of spinal nerves
and associated ganglia

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19
Q

2 types of efferent fibers of peripheral nerves

A

1: somatic motor fibers: terminate in skeletal muscles
2: visceral motor (autonomic) fibers: which innervate cardiac muscle, smooth muscle, glands and adipose tissue

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20
Q

Termination of a somatic motor fiber on a skeletal muscle fiber occurs at the?

A

motor end plate or neuromuscular junction

which resembles a synapse

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21
Q

efferent

A

motor

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22
Q

afferent

A

sensory

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23
Q

2 types of afferent fibers of PNS

A

each afferent fiber conducts impulses toward the SC or brain from the particular sensory receptor (touch, pain, auditory, taste)

1: somatic sensory fibers: arise in sensory receptors of the body wall (skin, muscle and bone)
2: visceral sensory fibers: arise in the internal organs and in the walls of blood vessels throughout the body

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24
Q

3 parts of the brain

A

cerebrum

cerebellum

brain stem

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25
Q

a deep medial longitudinal fissure separates…

A

the left and right cerebral hemisphere

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26
Q

the surface of each hemisphere is wrinkled by the presence of eminences known as?

A

gyri and furrows

which are called sulci or fissures

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27
Q

the cerebral cortex consists of..

A

a layer of gray matter that is 1.3-4.5 mm in thickness and covers the expansive surface of the cerebral hemisphere

this cortex is estimated to contain 14 billion nerve cells

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28
Q

2 major grooves on the lateral surface of the brain

A

central sulcus (of Rolando)

lateral fissure (of Sylvius)

29
Q

how many lobes in the cerebral hemispheres?

A

6

1-FRONTAL LOBE (anterior to central sulcus and above lateral tissue)

2- OCCIPITAL LOBE (caudal to parieto-occipital fissure to preoccipital notch

3- PARIETAL LOBE- (extends from central sulcus to parieto-occipital fissue; separated from temporal lobe by lateral fissure)

4- TEMPORAL LOBE- (below lateral fissure)

5- LIMBIC LOBE- (a ring of cortical tissue consisting of paraterminal gyrus

6- INSULAR LOBE- consists of cortical tissue that forms the floor of the deep lateral fissure

30
Q

are the gyri and sulci of the frontal, parietal, occipital and temporal lobes continuous on the medial surface of the cerebral cortex as those seen on the lateral surface??

A

yes

31
Q

where is the cerebellum attached?

A

to the dorsal surface of the brain stem at the level of the pons

32
Q

the surface of the cerebellum is similar to the cerebrum because it..

A

consists of a layer of gray matter (CEREBELLAR CORTEX) which is arranged in ridges and grooves

33
Q

folia=

A

the ridges of cortical gray matter

34
Q

the brainstem consists of..

A

medulla

pons

midbrain

35
Q

do all pairs 12 pairs of the cranial nerves attach to the brain stem?

A

No

CN I (olfactory) and CN II (optic) do not

36
Q

what are ventricles?

A

cavities within the brain

filled with cerebrospinal fluid (CSF) (produced by specialized tissue inside the ventricles called choroid plexus)

37
Q

through 3 openings in the medulla, CSF flows from the ventricles into the…

A

subarachnoid space- which surrounds the brain and SC

38
Q

what are the 3 CT membranes that enclose the CNS and constitute the meninges? (meningial layers)

A

1- pia matter- intimately attached to the surface of the brain and SC

2- arachnoid

3- Dura matter- tough, lines the bony cranial cavity around the brain and the vertebral canal around the SC

39
Q

subarachnoid space is located ..

A

between the pia mater and the arachnoid (2 layers of the 3 CT membranes that enclose the CNS

40
Q

the SC is anchored through the arachnoid to the dura mater by…

A

paired lateral septa of pia called DENTICULATE LIGAMENTS

41
Q

the SC is divided arbitrarily into 5 regions..

A 
cervical
thoracic
lumbar
sacral
coccygeal
42
Q

enlargements in the lower cervical region and in the lumbosacral region of the SC contain..

A

the cell bodies of nerve fibers supplying the upper and lower limbs

43
Q

spinal nerves are attached to the SC in pairs:

A 
8 cervical pairs
12 thoracic pairs
5 lumbar pairs
5 sacral pairs
1 coccygeal pair
44
Q

each nerve is formed by..

A

the union of dorsal root and a ventral root

45
Q

a dorsal root is composed of?

A

sensory or afferent fibers

the sensory fibers of the dorsal root are processes of sensory neuron cell bodies in the dorsal root ganglia

46
Q

a ventral root is composed of?

A

motor or efferent fibers

the motor fibers in the ventral root are axons of neuron cell bodies in the spinal cord

47
Q

conus medullaris=

A

the tapered end of the SC since it does not extend to the lowest level of the bony vertebral canal but rather ends at the level of the lower border of the 1st lumbar vertebra

because the SC is ~25 cm shorter than the verebral column, the lower segments of the SC are not aligned opposite corresponding vertebrae–> the lumbar and sacral spinal nerves have very long roots, extending from ther respective segments in the SC to the lumbar and sacral INTERVERTEBRAL FORAMINA

48
Q

filum terminale=

A

the pia mater that continues caudally as a CT filament over the conus medullaris

it passes through the subarachnoid space to the end of the dural sac at the level of vertebra S1 where it receives a covering of dura and continues to its attachment to the coccyx

49
Q

at each intervetebral foramina…

A

a dorsal root and a ventral root join to form a spinal nerve

the spinal nerve roots descend in a bundle from the conus (resembles the tail of a horse)= CAUDA EQUINA

50
Q

cauda equina=

A

a bundle of spinal nerves descending from the conus medullaris

51
Q

the white matter of the SC gets divided into?

A

dorsal, lateral and ventral funiculi

by the dorsal median sulcus, ventral median fissure, dorsolateral and ventrolateral sulcus

52
Q

the ratio of white matter to gray matter in the SC is greater at..

A

at cervical levels because the white matter in the cervical region contains fibers connecting the entire SC with the brain- fibers must pass through ( the lumbosacral cord contains only fibers serving the caudal end of the SC

53
Q

gray matter of the SC contains..

A

dorsal and ventral horns and small lateral horns (found in the thoracic and upper lumbar segments

54
Q

ventral horns are larger in the…

A

cervical and lumbosacral regions than in the thoracic region because the muscle mass of the limbs is greater than that of the trunk and these horns are made up largely of cell bodies of neurons that innervate skeletal muscles

55
Q

laminae=

A

distinctive layers or “laminae”, are arranged from dorsal to ventral within the gray matter (longitudinal cell columns when the SC is cut along its length)

each lamina extends the length of the cord

lamina I-VI are confined to the dorsal horn (lamina I is the most dorsal)

lamina IX is restricted to the ventral horn and consists of several different columns of cells

56
Q

cells in laminae I-VI..

A

receive and transmit information concerning sensory input from the spinal nerve afferents

fiber pathways from other SC levels and the brain also synapse on cells in these laminae

57
Q

the columns of cells in lamina XI consist of..

A

each cell column consists of alpha, beta and gamma motoneurons which send their axons into the ventral roots of the spinal nerves and innervate skeletal muscles

58
Q

the adult human NS originates in the?

A

ectoderm of the embryo

59
Q

initially, a rostrocaudal groove appears in the midline of the embryonic ectoderm, then…

A

this NEURAL GROOVE is flanked by NEURAL FOLDS which then close to form a NEURAL TUBE

the rostral end of this tube develops into the brain and the remainder differentiates into the SC

60
Q

the neural tube closes first at the..

A

level destined to be the upper cervical region of the SC

from this point, closure proceeds both rostrally and caudally

61
Q

the final closure at the ends of the neural tube typically occurs during?

A

the 4th week of embryonic life

62
Q

partial or complete failure of closure of the posterior neuropore results in?

A

spina bifida- a common deveopmental abnormality

63
Q

the tissue comprising the neural tube contains several different types of cells..

A

neuroblasts- primordial neurons

glioblasts- primordial astrocytes and oligodendrocyts

64
Q

the single layer of cells lining the tube later becomes the?

A

ependyma- which lines the ventricles of the adult brain

65
Q

ectodermal tissue lateral to the neural tube constitutes the?

A

NEURAL CREST
a collection of cells that differentitate into the neurons and glia of the PNSas well as a variety of nonneural structures

elements derived from the neural crest ultimately give rise to autonomic ganglia and most of the sensory ganglia of the body and head as well as glial cells of the PNS

66
Q

development of the brain begins with differentiation of 3 swellings/vesicles as the rostral end of the neural tube:

A

prosencephalon

mesencephalon

rhombencephalon

67
Q

5 vesicle stage of development consists of

A

the first 3 of these vesicles eventually differentiate into the cerebral hemispheres

telencephalon

diencephalon: thalamus & hypothalamus & midbrain
mesencephalon:
metencephalon: becomes the cerebellum & pons
myelencephalon: becomes the medulla oblongata

68
Q

the arrangement of 5 vesicles is established by the time the embryo is

A

6 weeks

69
Q

what is the major change in form that produces the adult human brain after 6 weeks?

A

tremendous growth of the cerebral hemispheres and cerebellum relative to other parts of the brain

Neuro (48 decks)

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