Lecture 13 CNS Flashcards
Development of the CNS
CNS develops from neural tube of embryo starting around 3 weeks
anterior neural tube first differentiates into forebrain, midbrain, and hindbrain (4weeks)
forebrain greatly enlarges to form cerebral hemispheres
Supporting structures of the CNS
meninges
brain ventricles and cerebrospinal fluid (CSF)
Glial cells
Meninges
Dura mater - outer layer
Arachnoid mater - middle
Pia mater - inner layer
Brain ventricles and CSF
CSF is produced by the choroid plexuses of the brain ventricles
CSF circulates through ventricles and into subarachnoid space
CSF composition is regualted; low protein concentration compared to plasma
Glial cells
supporting cells of the NS astrocytes microglia oligodendrocytes ependymal cells
Astrocytes
provide physical and metabolic support to neurons
blood-brain barrier- tight junction between capillary endothelial cells
regulates passage of substances from blood to CNS interstitial fluid
microglia
phagocytes, protective functions
oligodendrocytes
myelinate axons in CNS
ependymal cells
produce CSF
Spinal Cord
Gray matter
nuclei, contain cell bodies, dendrites, axon terminals integration areas of CNS
dorsal (posterior) horn
ventral (anterior) horn
Spinal Cord
White matter
tracts (bundles of axons in the CNS)
contains myelinated areas
conduct APs over long distances
ascending tracts & descending tracts
Ascending tracts
sensory information
carries info to the brain in the dorsal white columns
Descending tracts
motor information
down to appropriate level of the spinal cord and then out to the appropriate body part
in lateral anterior parts of white matter
Ganglia
clusters of cell bodies in the PNS
Spinal nerves
Dorsal Root
incoming axons of sensory neurons
cell bodies in dorsal root ganglia
Spinal nerves
Ventral Root
outgoing axons of motor neurons
cell bodies in ventral horn
How many pairs of spinal nerves
31 pairs
C1-8, T1-12, L1-5, S1-5 Co1
Spinal Reflexes
Parts of the reflex arc
sensory receptor sensory neuron integration center motor neuron effector (muscle)
2 spinal reflexes
monosynaptic reflex (e.g. muscle spindle stretch reflex) polysynaptic reflex (e.g withdrawal reflex and crossed extensor reflex
Brain stem
medulla ,pons, and midbrain
transition from spinal cord to higher brain regions
sensory motor tracts pass through
origins of cranial nerves
reticular formation
network of neurons involved in arousal of cerebral cortex (sleep/wake)
Medulla Oblongata
ascending (somatosensory) tracts convey sensory information to higher brain areas
descending (corticospinal) tracts carry motor signals, cross over in pyramids of the medulla
respiratory and cardiovascular control centers
other involuntary control centers (swallowing, vomiting)
Pons
connections between cerebellum and other CNS areas
respiratory centers coordinate with medulla to control breathing
Midbrain
visual and auditory reflexes
role in unconscious motor control (red nucleus, substantia nigra)
Cerebellum
major role in coordination of movement
cortex (gray matter)
arbor vitae (white matter)
Parts of the diencephalon
thalamus
hypothalamus
pineal gland
thalamus
sensory “relay station” from lower CNS centers to the cerebral cortex
hypothalamus
major center for homeostasis
regulates appetite, thirst, body temp
regulate endocrine function via control of the pituitary gland
activates sympathetic division of ANS
mediates physiological responses of emotional states (via autonomic NS)
Pineal gland
endocrine gland
secretes melatonin
Cerebrum
higher brain functions, sensory perception, voluntary control of movement
lobes: frontal, parietal, temporal, occipital
Cerebral gray matter
cerebral cortex
basal ganglia
limbic system
Cerebral white matter
association fibers
commissural fibers (corpus callosum) - connect 2 hemispheres
projection fibers - ascending and descending tracts
Basal ganglia
deep gray matter areas, involved in subconscious control of movement
part of cerebrum
Limbic system
emotional brain
amygdala - control center of strong emotions (fear, anger) role in memory processing
hippocampus - major role in consolidation of long term memory
Cerebral cortex
highest level processing and integration area
what makes you, you
gyri and sulci increase surface area
6 distinct cell layers of cortex
functional areas of the brain
cerebral lateralization (left brain- right brain)
Frontal love
primary motor area
speech (Broca’s) area
prefrontal cortex - higher level thinking, plannin, judgement, personality
Parietal lobe
primary somatosensory area
sensory association areas
Occipital lobe
visual cortex
temporal lobe
auditory cortex language association (Wernicke's) area
