anat Flashcards

1
Q

neurons responsibility

A

□ Signal transduction within neurons: electrical (mem potential)

□ Signal transduction between neurons: biochemical (synapse)

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2
Q

types of neurotransmitters

A

Glutamate (excitatory)
□ Pyramidal neurons in neocortex (CNS)
□ Learning, memory

GABA (inhibitory)
□ Receptors are drug targets for sedatives - benzodiazepines

Acetylcholine (excitatory)
□ Nucleus basalis of Meynert
□ Excitatory at NMJ
□ Learning, arousal, reward

Dopamine (inhibitory)
□ Mem of monoamine fam (noradrenaline, adrenaline, serotonin)
□ Major source from Substantia nigra
□ Involved in motor system, reward

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3
Q

Ach synthesis, transporters, receptors, catabolism

A
  1. Synthesis: choline acetyltransferase
  2. Transporters: VAChT and SDHACU
  3. Receptors
    a. Presynaptic = regulate - m2 muscarinic receptors
    b. Postsynaptic = action (activate/ inhibit)
    c. GPCR (mAChR muscarinic) and ion channels (nAChR nicotine)
  4. Catabolism: AChE acetylcholinesterase
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4
Q

synaptic initiation – neurotransmitter release

A
  • Vesicles containing neurotransmitter at cytoskeleton (away from presyn mem) by Ca2+ sensitive vesicle mem proteins (VAMPs)
  • When AP reach terminal, open voltage-gated Ca2+ channels –> Ca2+ influx
  • VAMPs bring vesicle from exoskeleton and facilitate vesicle docking, fuse, exocytosis from presynaptic mem
    □ Release neurotransmitters
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5
Q

regulation of Ach release

A

presynaptic auto receptors (m2 muscarinic receptors)

inhibit further transmitter release via feedback inhibition

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6
Q

propagation // termination of neurotransmitters

A
  • Neurotransmitters in synaptic cleft activates postsynaptic receptors
    □ GPCR = 2nd messenger activation
    □ Ion channels = depolarisation, propagate AP
  • Signal termination by catalytic enzymes/ reuptake transporters
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7
Q

excitatory vs inhibitory synapse

A

excitatory:
- presynaptic neurotransmitter release directly correlates with postsynaptic depol/ signalling

inhibitory synapse:
- presynaptic neurotransmitter release (GABA) inverse correlates with postsynaptic depolarisation/ signalling

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8
Q

CNS

A

brain + spinal cord

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9
Q

PNS

A

cranial nerves (12 pairs)

spinal nerves (31 pairs)

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10
Q

forebrain

A
  • Cerebrum
    ◊ Largest part of brain
    ◊ 2 hemispheres
    * Separated by longitudinal fissure
  • Diencephalon – hypothalamus, thalamus
    Hypothalamus: lower part of lateral wall and floor of 3rd ventricle
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11
Q

midbrain

A

topmost part of the brainstem, the connection central between the brain and the spinal cord.

Connect forebrain to hindbrain
- dopamine, serotonin

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12
Q

midbrain

cranial nerves
nuclei assoc with
fiber tracts

A
  • Cranial nerves (III,IV)
  • Nuclei associated with
    • III, IV, V
    • Visual and auditory pathways
  • Fiber tracts
    • Ascending and descending fibers
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13
Q

hindbrain

A

medullar oblongata (most inferior of brain)
pons (superior of medulla)
cerebellum (posterior of pons and medulla)

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14
Q

medulla oblongata

cranial nerves
nuclei assoc with
fiber tracts

A

Cranial nerves
* IX, X, XI, XII

Nuclei associated with
* V, IX, X, XI, XII
* Cardiovascular and resp function

Fiber tracts
* Ascending and descending fibers

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15
Q

Pons

cranial nerves
nuclei assoc with
fiber tracts

A
  • Cranial nerves
    * V, VI, VII, VIII
  • Nuclei associated with
    * V, VI, VII, VIII
  • Fiber tracts
    * Ascending and descending fibers
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16
Q

4 lobes of the brain

A

frontal

parietal (middle)

temporal (side)

Occipital (back)

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17
Q

spinal cord (PNS) is connected to

A

Continuous with brain — foramen magnum of skull

Tapers off into — conus medullaris

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18
Q

brain and spinal cord is covered by

A

brain:
§ Located in cranial cavity. Under meninges, skull
§ surrounds brain in subarachnoid space

sc:
§ Located in vertebral column
§ Protected by
□ meninges
□ Surrounded by cerebrospinal fluid (CSF)

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19
Q

spinal cord grey and white matter

A

grey: dorsal and ventral horn (cell bodies)

white: outer region (axons)

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20
Q

cell types in CNS and PNS

A

CNS: neurons, glial cells (astrocytes, oligodendrocytes, microglia)

PNS: sensory & motor neuron, schwann cells, satellite cells

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21
Q

CNS cells (neurons vs glial cells)

A

neurons
- structural, functional
- generate/ conduct impulses, excitable
- 100 billion

glial
- non conducting
- support and protect neurons
- 1000 billion

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22
Q

parts of neuron

A

1) cell body (soma) – mitochondria, GA

2) axon – lacks ribosomes, RER, GA
3) dendrite – all cytoplasmic components except GA

  • has dendritic spines, where synapse can take place
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23
Q

axon <–> soma transport

fast vs slow component

A

to: anterograde transport
from: retrograde transport

1) Fast component (50 - 400mm/day) transport cytoplasmic proteins, macromole required for metabolic and synaptic activity

2) Slow component (1 - 4mm/day) transports cytoskeletal components down axon. maintenance

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24
Q

synapse: Impulses transmitted from __ to __ at regions of functional apposition

A
  • 1 neurons (PRESYNAPTIC) to another neuron (POSTSYNAPTIC)
  • Neuron to effector cell (muscle)
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25
electrical synapse vs chemical synapse
electrical: gap junction b. 2 neurons, no space in between, faster chemical: synaptic cleft present (20 - 40nm wide), receptors for neurotransmitters found on postsynaptic cell, slower
26
pre vs post synaptic cells
pre: thickened region in the plasmalemma of axon terminal - voltage gated Ca2+ channels (trigger EXOCYTOSIS) post: thickened region in the plasmalemma of dendrite with neurotransmitter receptors
27
glial cells in CNS main functions
1) astrocytes (regulate environment, struc support) 2) oligodendrocytes (myelin sheath formation several axons) 3) microglia (macrophage)
28
glial cells in CNS makeup
astrocytes 25% oligodendrocytes 60-80% microglia 5-10%
29
astrocytes feature
largest neuroglial cells numerous processes w/ pedicles that terminate on capillaries/ on pia mater
30
types of astrocytes
1. Fibrous astrocytes * White matter * Long spindly process with few branches * BBB formation 2. Protoplasmic astrocytes * Gray matter * Thick, lightly branches processes ---| * Closely apposed to neuron cell bodies * Support neuron
31
function of astrocytes
* BBB * Structural support, scar formation -- neurons & SYNAPSES * metabolise neurotransmitters (glutamate shuttle -- astrocytic process/ tripartite synapse) * mediate exchange of nutrients and metabolites b. blood and neurons * Secretion of nerve GF * Water transport * Excess transport (Cerebral oedema) * regulate composition of intercellular environ and entry of sub
32
oligodendrocytes feature
In white matter * Predominant type of neuroglial cells * Produce (several axons) myelin sheath around myelinated fibers in white matter In grey matter * Oligodendrocytes are closely assoc with neuron cell bodies * Function as satellite cells, support
33
oligo produces
1. Cell marker -- CNPase 2. Express Nogo-A a. Myelin associated neurite outgrowth inhibitor b. Inhibit axonal regeneration following injury and ischemia in CNS 3. Satellite cells, support
34
microglia features
small phagocytic cells that enlarge and become mobile after CNS injury monocyte origin
35
microglia function
* Brain macrophage * Phagocytosis * Secretion of proinflamm cytokines (neuroinflammation) ○ TNFa, IL1 b ○ Chemokines Implicated in Alzheimer's disease, Parkinson, cerebral ischemia (stroke) * APC (MHC II antigen) * Immunocompetent cells of CNS
36
PNS composed of
- neuron processes and cell bodies located outside CNS - neuroglial cells [schwann & satellite cells] - nerve endings
37
peripheral nerve structure 3 connective tissue elements
Nerve fibers (axon) --> bundles/ (fascicles) --> nerve 1) Each nerve (axon) fiber have endoneurium myelin sheath ◊ Thin, reticular layer that surrounds each individual nerve fiber ◊ Contains Schwann cells 2) Each nerve bundle/ fascicle covered by perineurium dense connective tissue 3) Entire nerve covered by epineurium connective tissue
38
schwann cells
myelinate portions of only a single axon
39
satellite cells
- amphicytes - Form capsule of cells around neuron cell bodies located in peripheral ganglia
40
ganglia (portion of PNS)
* Encapsulated collections of neuron cell bodies, located outside CNS * Contains: □ Satellite cells (amphicytes) □ Connective tissue elements □ Neurons * dorsal -- sensory neuron (to dorsal horn)
41
BLOOD SUPPLY of brain
GO READDDD from the slides 1) Common carotid artery in neck --> INTERNAL CAROTID (L,R) --> middle & anterior cerebral 2) subclavian artery in neck --> VERTEBROBASILAR (L,R) --> posterior cerebral
42
circle of willis
Anastomosis between left and right arteries supplying the brain b. vertebral and internal carotid arteries □ Located at base of brain 1. Anterior communicating artery a. Connects anterior cerebral arteries of both sides 2. Posterior communicating artery a. Connects middle cerebral artery with posterior cerebral artery
43
circle of willis and slow occlusion in 1 artery
□ Communicating arteries have time to enlarge and accommodate to incr blood flow □ Blood can still pass around the other way to reach affected area -- collateral circulation ** Not if sudden occlusion
44
Haemorrhagic stroke
Circle of Willis freq site of aneurysms Abnormal out-pocketing of wall of a blood vessel esp at junction where basilar artery splits into posterior cerebral arteries
45
venous drainage of brain
Blood from brain drains into venous sinuses --> empty into internal jugular vein READ FROM SLIDES (split into superior, inferior, central part of brain)
46
ventricles in brain
lateral 3rd 4th central canal
47
patho of brain venous drainage --- Subdural hemorrhage
* Rupture of cerebral vein (occur b. superior cerebral veins) as it drains --> superior sagittal sinus * Low venous pressure in brain □ Slow seepage -Wks ltr after blow has been forgotten -Slow expanding hematoma press on brain □ Sx: dizzy, headache, apathy, falling, confusion, drowsiness
48
BBB and capillaries 1) found where? 2) formed by? 3) function?
* TIGHT JUNCTIONS b. endothelial cells, form BBB * Formed by astrocytes * Prevent random entry of water soluble sub into brain parenchyma
49
intracranial pressure (ICP)
generally measured as CSF pressure (cerebrospinal fluid) reflects change in volume of IC contents
50
CSF produced in
choroid plexus (80%) by ependymal cells rest is secreted in interstitial spaces of brain reabsorbed through arachnoid granulation and dural sinus
51
CSF surrounds __
ventricles and central canal bathes brain and spinal cord in sub-arachnoid space
52
sub-arachnoid space
space b. 2 meninges (arachnoid mater & pia mater – below)
53
function of CSF
* shock absorber to protect brain * clear waste (remove metabolites from brain, since no lymphatic system) * distribution of material via CSF * buoyancy of brain (decr brain weight)
54
skull made up 3 major components
85% brain 7% blood 7% CSF
55
frontal lobes
sensation and perception voluntary control of movement (somatomotor cortex) personality traits learning and memory LANGUAGE: left hemi left side of body: right cortex
56
broca’s area
expressing language, speak
57
wernicke’s area
○ comprehend language
58
parietal lobe
○ Sensory info from body ○ 1* somatosensory cortex: sense of touch (frontal) sensorimotor cortex: coordination and balance - execution of movements of the contralateral side of the body - TOPOGRAPHIC representation
59
somatosensory cortex vs somatomotor cortex
sensory: Parietal. processing sensations from various parts of the body. motor: precentral gyrus of the frontal lobe. Processing movements of those bodyparts
60
occipital lobe
Visual info processed
61
temporal lobe
auditory info
62
limbic structures
thalamus, hippocampus, hypothalamus, amygdala add memory and emotions to sensory experiences declarative memory: recollection by hippocampus non-declarative memory: recollection through actions
63
amygdala
recognition of facial expression emotion and emotional memory, fight or flight
64
brainstem and cortex
execution of behaviours sends long axons from site of origin to spinal cord
65
basal ganglia
midbrain region - initiation - selection of motor program * degeneration of dopamine neurons in basal ganglia: parkinson’s disease * (disorder of movement - bradykinesia, tremor, disorder of posture - rigid)