Central Nervous System Flashcards
astrocytes
- physically supports neurons
- serves as scaffold during fetal brain development
- induced formation of the BBB
- form neural scar tissue
- help transfer nutrients from the blood to the neurons
oligogendrocyes
-form myelin sheaths in CNS
microglia
- defense of the brain as phagocytic scavengers (phagocytosis)
- release nerve growth factor
ependymal cells
- lines inner cavities of the brain and spinal cord
- contributes to the formation of CSF
- potential to form new neurons and glial cells
cerebral spinal fluid (CSF)
- surrounds and cushions brain and spinal cord
- shock-absorber to prevent the brain from hitting the skull
- exchanging of materials between neural cells and interstitial fluid surround brain
- constant production and flow out of CNS
- produced in brain ventricles (choroid plexuses)
- exits 4th ventricle
blood and oxygen to the brain
- depends on constant blood supply
- cannot produce ATP without O2
- uses glucose but does not store any
- resting conditions: brain uses 20% of the O2 and 50% of glucose consumed in the body
cerebrum
- makes up 80% of total brain weight
- divided into left and right hemispheres
- each hemisphere is divided into lobes (frontal, temporal, occipital and parietal)
- connected by the corpus callosum
central nervous system (CNS)
- consists of the brain and spinal cord
- receives input from external environment–> CNS sorts and process via interneurons–> efferent neurons carry instructions to desired area
somatic nervous system
-consists of fibers of motor neurons that supply the skeletal muscle
autonomic nervous system
-consists of fibers that innervate smooth and cardiac muscles and glands
enteric nervous system
-extensive nerve network in the wall of the digestive tract
interneuron
- 99% of all neurons
- lie entirely within the CNS
- receiving information from afferent neuron
- multipolar
afferent neuron
- afferent division of PNS
- sensory receptor at peripheral end that generates action potentials
- unipolar
efferent neuron
- lie primarily in the PNS
- cell bodies originate in the CNS
- multipolar
DAP
- dur mater
- arachnoid mater
- pia
dura mater
- tough, inelastic covering
- consists of 2 layers
- dural sinuses: blood filled cavities
- venous sinuses: drains venous blood from the brain (returning to heart) and CSF reenters the blood here
arachnoid mater
- delicate, richly vascularized layer
- “cobwebby” appearance
- subarachnoid space is filled with CSF
arachnoid villa
- penetrate through gaps in overlying dura into the dural sinus
- CSF is reabsorbed across the surfaces into the circulating blood
cerebral cortex
- gray mater outter
- white matter central core
- houses basal nuclei
- sensory perception
- voluntary control of movement
- language
- personality traits
- sophisticated mental events, ex. thinking
gray matter
-organized into 6 well defined layers
-integration of neural input and initiation of neural output
-unmyelinated
Stellate cells- initial processing of info into the cortex
Pyramidal cells- send signals down the spinal cord to effector motor neurons
white matter
- consists of bundles of nerve fibers that interconnect brain areas
- axons, myelinated
somatosensory cortex
- front portion of each parietal lobe behind central sulcus
- initial processing and perception of somesthetic and proprioceptive input
- receives input from opposite side of body
- input from specific areas of the body
- distribution map: homunculus
somesthetic sensations
- sensations from the surface body
- heat, touch, pressure, cold and pain
proprioception
-awareness of body position
primary motor cortex
- front of central sulcus
- controls voluntary movement produced by skeletal muscles
- control muscles on opposite side of body
- motor homunculus
- fine control movements occupy larger area of motor homunculus
- does NOT initiate voluntary movement
- influenced by supplementary motor area, premotor cortex, posterior parietal cortex, cerebellum and basal nuclei
broca’s area
- location: left frontal lobe near motor areas
- controls speaking abiliy
Wernicke’s area
- location: left cortex and the juncture of parietal, temporal and occipital lobes
- language comprehension of both spoken and written messages
- responsible for formulating coherent patterns of speech–> broca’s area
left cerebral hemisphere
- logical
- analytical
- sequential
- verbal tasks
- math
- language forms
- philosophy
- process information into fragments
right cerebral hemisphere
- non-language skills
- spatial perception
- artistic
- musical talents
- sees “big picture”
basal nuclei (basal ganglia)
- several masses of gray matter deep within white matter
- inhibit muscle tone throughout the body
- selecting, maintaining purposeful motor activity
- suppressing unwanted patterns of movement
- coordinates slow, sustained contractions
- Parkinson’s disease
Parkinson’s disease
- gradual destruction of neurons that release dopamine in the basal nuclei
- motor disturbances: increased muscle tone (rigidity), involuntary/useless/ unwanted movements (resting tremors), slowness in initiation and completing motor behaviors
thalamus
- reinforces voluntary motor behavior from motor cortex
- “relay station” and synaptic integrating center for sensory input
- helps direct attention to stimuli of interest
- capable of crude awareness of sensations, cannot distinguish location or intensity