CNS (4) Flashcards
parts of the CNS
brain and spinal cord
- aka is a collection of neurons that forms specialized signaling networks
brain: encased by the bones of the cranium
spinal cord: runs through the bones of the vertebral column
meninges (def, function + parts)
= tissue membranes that lie between bones and the soft tissues of the CNS
stabilizes and protects neural tissue
- dura matter
- arachnoid membrane
- subarachnoid space contains cerebrospinal fluid - pia mater
ventricles of the brain: def
a communicating network of cavities
- lateral ventricles = 1st and 2nd ventricles
- through brain stem and into spinal cord via central canal = 3rd and 4th ventricles
ventricles of the brain: functions
produces CSF
physical protection… PROTECT
- keeps brain tissue buoyant to reduce pressure and protect from mechanical insult
- absorbs shock
chemical protection… CLEAN UP
- BBB
- delivers nutrients to the brain and removes waste
- allows for a tightly regulated extracellular environment
where is CSF produced, and what is this areas function?
in the choroid plexus of the ventricles
- capillaries and ependymal cells meet here
- plasma gets filtered into ventricles
therefor the choroid plexus has ependymal cells selectively transport solutes, and water follows by osmosis
CSF and plasma
similar chemical composition but CSF has very low protein content
how is CSF reabsorbed to blood, from the subarachnoid space
via the arachnoid villi that project into the venous space
- nutrients from CSF play a big role here in blood!
CSF adult volume and turnover rate
150mL in adult ventricles
turns over 3-4x/day
rate of secretion and absorption is equal
BBB
has tight junctions and astrocyte foot processes
- acts as a border control
BBB and tight junctions + ex
brain capillaries have tight junctions that prevent movement of larger solutes between endothelial cells
ex: limits movement of hydrophilic substances that would pass easily via the paracellular pathway of exchange epithelium
**these capillaries can be super leaky in nephron
BBB and astrocyte foot processes
secrete paracrines onto endothelial cells that
promote tight junction formation
- also responsible for upregulating and maintaining the structure of tight junctions
- are essentially little pads covering up the capillaries
BBB and lymph system
takes care of any leaky capillaries in the BBB
metabolic needs of O2 in neural tissue
passes via diffusion freely across BBB
brain gets 15% of blood pumped by heart at rest
**this % is a constant amount that is determined by need
metabolic needs of glucose in neural tissue
brain is responsible for about 20% of body
total glucose consumption
- important because progressive hypoglycemia leads to confusion which lead to unconsciousness and then death
how does glucose cross the BBB
via ependymal cells w apical or basolateral transporter
what cannot the brain do with glycogen/FA metabolism
use it when glucose is low
- cardiac and skeletal muscles can do this
gray matter
made up of nucleus (clusters of cell bodies) and dendrites, synapses, axon termini
brain: superficial and then deep inside too
spine: inside
divided into dorsal (sensory,afferent) and ventral (motor,efferent) horns
- pseudounipolar sensory neurons also present
- cell bodies live in dorsal root ganglion
white matter
made up myelinated axons, FEW cell bodies
brain: under brain
spine: superficial
- divided into dorsal, ventral, and lateral columns
- has ascending tracts and descending tracts
brainstem parts
medulla, pons, midbrain
medulla (5)
part of the brain stem: networks for automatic function
breathing, cardiovascular, swallowing, vomiting, has ‘pyramids’ as a crossover region for corticospinal tracts
pons
part of brainstem: relay station of autonomic pathways
has some neurons for respiration
midbrin
part of brainstem: network for eye movements and hearing
5 ex of cranial nerves: OOVGV
1: olfactory - sensory: smell info from nose
2: optic - sensory: visual info from eyes
8: vestibulocochlear - sensory: hearing and equilibrium
9: glossopharyngeal - mixed:
- sensory from oral cavity
- chemoreceptors in blood vessels
- efferent for swallowing
- parotid salivary gland secretion
10: vagus - mixed: sensory and efferent to internal organs, muscles and glands
gray matter of the cerebrum: 2 parts
cerebral cortex
basal ganglia
… and limbic system
basal ganglia
part of gray matter of cerebrum
involved into control of limb/eye movements and cognitive functions
- help you perform and complete a movement
lesions of basal ganglia = loss of neurons here = contribute to parksinsons and huntingtons
cerebral cortex
part of gray matter of cerebrum
contains SENSORY AREAS for perception, MOTOR AREAS to direct movement, and
ASSOCIATION AREAS to integrate information
- 5 parts: frontal, parietal, occipital, temporal and prefrontal cortex
surface is folded, sulci (line) divide the gyrus (thick)
thalamus
Relay station: receives afferent sensory & motor info, projects fibers to cerebrum for info processing
hypothalamus + 2ex
homeostasis and behavior
- maintains body temp: shivering/sweating
- controls body osmolarity: thirst/drinking behavior: secretion of vasopressin
pituitary gland
Anterior: secretes hormones
Posterior: secretes neurohormones that are made in the hypothalamus
- ex: oxytocin and vasopressin
how do the neurohormones secreted by the pituitary gland lay
cell body of neuron in hypothalamus & synaptic terminal in posterior pituitary
pineal gland
secretes melatonin and regulates sleep-wake cycle
- cyclic with day/night via photopreceptors
tropic vs trophic
tropic = hormone causes a release of another hormone
trophic = hormone causes growth of something
limbic system parts
cingulate gyrus - emotion
hippocampus - learning and memory
amygdala - emotion and memory
limbic system location/function
around the brainstem
links higher, cognitive regions of the cerebrum
with more primitive functions
- has centers for emotion, memory & learning
cerebellum
= little brain
involved in the control of movement & posture, motor learning, adaptation of body & eye movements
integrates sensory and efferent information to ensure movement is coordinated
cerebellum inputs vs outputs
Inputs: from all senses (body, visual, auditory, vestibular)
- receives copies of outgoing commands from the motor cortex
Outputs: sent to cortex via thalamus & to spinal cord via the brain stem for control of movement
brocas area vs wernickes area
brocas: expression and vocalization
wernickes: comprehension and integration
damage to brocas area vs wernickes area
brocas: expressive aphasia
- comprehension is maintained but lose ability of expression in spoken language
wernickes: receptive aphasia
- expression without meaning is maintained but lose comprehension ability
