Chapter 14 - Brain Flashcards

1
Q

Some characteristics of the brain

A
  • most nervous tissue located here
  • 99% of all neurons in body located in CNS
  • 20% of body’s blood flow goes to brain
  • 100 billion neurons (1,000 times more than spinal cord)
  • major integration center - control centers located in brain
  • high metabolic rate
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2
Q

Embryonic Development of brain

A

Primary germ layers (16 day old after fertilization) - 3 layers

  1. Ectoderm
  2. Mesoderm
  3. Endoderm
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3
Q

Ectoderm

A

top layer; develops into nervous tissue & part of skin (epidermis); brain, spinal cord & nerves all come from this layer

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4
Q

Mesoderm

A

middle layer; develops into most muscle tissue (skeletal); CT; forms mesenchyme

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5
Q

Endoderm

A

develops into epithelial lining of digestive, respiratory, reproductive, urinary systems; epithelial tissue comes from ALL 3 layers

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6
Q

Formation of the ectoderm (beginning of the brain)

A

a. neural tube - ectoderm forms a long tube; upper region develops into brain & lower region develops into spinal cord
b. primary brain vesicles - upper part widens @ 3 regions
1. Forebrain - top
2. Midbrain - middle
3. Hindbrain - lower

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7
Q

Forebrain (embryo) develops into

A
  1. Cerebrum
  2. Diencephalon
    (of adult brain)
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8
Q

Midbrain (embryo) develops into

A

Midbrain (of adult brain)

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9
Q

Hindbrain (embryo) develops into

A
  1. Pons
  2. Medulla
  3. Cerebellum
    (of adult brain)
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10
Q

4 Major regions of brain

A
  1. Cerebrum - 83% of total brain mass
  2. Diencephalon - 3 parts - thalamus, hypothalamus, epithalamus
  3. Brain stem - 3 parts - midbrain, pons, medulla
  4. Cerebellum - 11% of brain mass; 2nd largest part
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11
Q

Protections of the Brain

A
  1. Skull bones
  2. Meninges - 3 CT coverings–continuous from spinal cord - dura mater, arachnoid mater, pia mater
  3. CSF - floats brain so it’s cushioned
  4. Blood-brain barrier (BBB)
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12
Q

Layers of meninges in brain

A
  • NO epidural space–no layer of fat
  • Dura mater–periosteal layer & meningeal layer
  • Subdural space
  • Arachnoid mater
  • Subarachnoid space - CSF
  • Pia mater - touches brain
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13
Q

Dura mater - 2 layers

A
  1. periosteal layer - periosteum of skull bones; fused onto dura mater; why there’s no epidural space
  2. meningeal layer
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14
Q

CSF

A

comes from blood; made in brain

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15
Q

choroid plexus

A

forms CSF

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16
Q

ventricles

A

spaces inside brain filled w/CSF; all connected

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17
Q

How CSF gets into the subarachnoid space

A
  • CSF first enters ventricles
  • 3 holes - apertures - how CSF gets into subarachnoid space
  • CSF is removed by arachnoid villi
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18
Q

arachnoid villi

A

folds of arachnoid mater; comes from arachnoid mater; drains CSF out of brain into a vein

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19
Q

Blood-brain barrier (BBB)

A

endothelial cells (epithelial cells) lining capillaries in brain have many tight junctions; very impermeable barrier protects the brain from harmful substances & pathogens

20
Q

Substances that cannot or poorly enter brain:

A
  • cells
  • proteins
  • waste products - urea, uric acid
  • most antibiotic drugs
  • K+ ions - pumped out of brain by active transport; if levels too high, threshold is not maintained
21
Q

Substances that can enter brain:

A
  • glucose
  • some amino acids
  • some ions - Na+, Ca+ (not K+ –want to keep K+ low)
  • oxygen - small nonpolar molecules; by simple diffusion
  • carbon dioxide
  • fats
  • alcohol - lipid soluble
  • anesthesia
22
Q

4 Main Parts of Brain

A
  1. Brain stem
  2. Cerebellum
  3. Diencephalon
  4. Cerebrum
23
Q

Brain stem (3 parts)

A
  1. Midbrain - top inch
  2. Pons - middle inch
  3. Medulla - bottom inch
24
Q

Brain stem characteristics

A

white & gray matter; 3 inches long; connections to cerebellum & lots of connections to PNS; connects brain to spinal cord; 10 cranial nerves exit out of brain stem

25
Q

Midbrain (brain stem)

A

coordinates head & eye movements; substantia nigra

26
Q

substantia nigra

A

dark pigmented region; location of neurons that don’t work in Parkinson’s; makes dopamine; located in midbrain

27
Q

Pons (brain stem)

A

respiratory center that moderates breathing; lots of connections to cerebellum

28
Q

Medulla (brain stem)

A

autonomic relay center; main respiratory center-sets normal pattern of breathing; cardiac center–can change heart rate; direct connections to heart; vasomotor center - direct connections to blood vessels–changes diameter of blood vessels

29
Q

Medulla- crossing over of corticospinal tracts

A

tracts comes from left side of brain & crosses over to right side @ medulla & supplies right side of body & vice versa; right side of brain controls left side of body & vice versa

30
Q

Cerebellum

A

looks like a little cerebrum; white & gray matter; function–subconscious coordination of body movements; does not control it but coordinates it; posture & balance affected by cerebellum; Ipsilateral - same side; 2 hemispheres - left hemisphere coordinates movements on left side

31
Q

Diencephalon (3 parts)

A
  1. Thalamus
  2. Hypothalamus
  3. Epithalamus
32
Q

Diencephalon

A

nuclei located here; tiny part; almost all gray matter; lots of cell bodies

33
Q

Thalamus (Diencephalon)

A

gateway to the cerebral cortex; all sensations (but smell); all receptors have to be cleared thru thalamus; sorts sensory info & relays to cerebral cortex

34
Q

Hypothalamus (Diencephalon)

A

under the thalamus; smaller than thalamus; 2-3% of brain; visceral control center; controls ANS, responsible for water balance, regulates sleep cycles; regulates hunger; responsible for body temp; homeostasis is accomplished thru here

35
Q

Hypothalamus (Diencephalon) - more info

A

parts of limbic system - sex drive, rage, animal instincts; endocrine glands - secretes lots of hormones which affect the pituitary gland (releases hormones); oversees pituitary gland; CONTROLS

36
Q

medulla receives info from hypothalamus

A

& carries out instructions

37
Q

ANS

A

beating of heart, secretion from glands

38
Q

Epithalamus (Diencephalon)

A

main structure is pineal gland which regulates sleep; pineal gland - secretes 1 hormone–melatonin; gland gets instruction from hypothalamus

39
Q

Cerebrum

A

largest part of brain; 2 halves - cerebral hemispheres - left & right - symmetrical

40
Q

convolutions

A

folds & creases of surface; grew rapidly; increases surface area - more blood vessels

41
Q

3 types of convolutions

A
  1. gyrus - upward fold; ridge
  2. sulcus - groove; downward fold
  3. fissure - deep groove
42
Q

longitudinal fissure

A

divides left & right cerebral hemisphere; deep fold

43
Q

transverse fissure

A

divides cerebrum from cerebellum

44
Q

central sulcus

A

divides frontal & parietal lobes

45
Q

parieto-occipital sulcus

A

divides parietal & occipital lobes

46
Q

lateral sulcus

A

divides temporal lobe from frontal & parietal lobes

47
Q

5 Lobes

A
  1. Frontal
  2. Parietal
  3. Occipital
  4. Temporal
  5. Insula - deep to lateral sulcus