week 4

nervous system functions

sensory input, integration, and motor output

what does the nervous system do

detects internat and external stimuli, processes info, and coordinates rapid responses

what does the nervous not do

transport nutrients or gasses

what does the cns consist of

brain and spinal chord

what does the cns serve as

primary integration and control center

what does the pns consist of

cranial nerves, spinal nerves, ganglia, and sensory receptors

what does the afferent (sensory) division do

carries impulses toward the cns

what does the efferent (motor) division do

carries commands from the cns to effectors

what does the somatic motor division control

voluntary skeletal muscles

what does the autonomic motor division control

involuntary smooth muscles, cardiac muscles, and glands

neurons characteristics

excitable, conductive, amitotic cells with high metabolic demands

major parts of neurons

dendrites, soma, axon hillock, axon, mylein sheath, nodes of ranvier, and synaptic knobs

most common neuron

multipolar neurons

interneurons are what

the most abundant functional type and perform integration

what do astrocytes do

maintain the blood-brain barrier and regulate the neuronal enviornment

what do oligodendrocytes do

myelinate cns axons

what do ependymal cells do

line ventricles and help produce and circulate cerebral spinal fluid (csf)

what are microglia

phagocytic immune cells of the cns

what do schwann cells do

myelinate pns axons and aid regeneration

what do satellite cells do

support neuron cell bodies with the ganglia

what does myelin do

increases conduction velocity by saltatory conduction between nodes of ranvier

what are nerves

bundles of axon in the pns

what does endoneurium surround

individual axons

what does perineurium surround

fascicles

what does epineurium surround

the entire nerve

what do chemical synapses use

neurotransmitters

what do electrical synapses use

they communicate thru gap junctions

synaptic transmission

action potential arrives —> calcium entry —> neurotransmitter release —> receptor binding —> postsynaptic response —> neurotransmitter removal

what do diverging circuits do

amplify information

what do converging circuits do

integrate multiple inputs

what do reverberating circuits do

generate repetitive activity such as breathing

what do circuits allow

simultaneous processing parallel after discharge

how do multiple sclerosis happen

from cns demyelination due to oligodendrocyte damage

what are the primary brain vesicles

forebrain, midbrain, hindbrain

what are the secondary vesicles

telencephalon, diencephalon, mesencephalon, metencephalon, and myelencephalon

what are the adult derivatives

cerebrum, diencephalon, midbrain, pons/cerebellum, and medulla oblongata. 

what does gray matter contain

neuron cell bodies

what does white matter contain

primarily myelinated axons

where is gray matter in the brain

superficial

where is white matter in the brain

deep

what is the corpus callosum

the major commissural tract

how do association fibers connect

within one hemisphere

what do projection fibers connect

cerebrum with lower cns centers

what does basal nuclei do

regulates voluntary movement

what does lentiform nucleus consist of

putamen and globus pallidus

where does the primary motor cortex lie

in the frontal lobe

where does the primary visual cortex lie

in the occipital lobe

what is thalamus

the major sensory relay for all senses except smell

what does the hypothalamus do

regulates homeostasis, autonomic activity, endocrine function, hunger, thirst, temp, circadian rhythm, and emotions

what does the epithalamus contain

pineal glands (which secrete melanin)

what does the infundibulum do

connects the hypothalamus to the pituitary gland

what does the midbrain contain

superior and inferior colliculi for visual and auditory reflexes

what does the pons contain

respiratory regulatory center

what does the medulla contain

cardiovascular, respiratory, and visceral reflex centers and is continuous with the spinal cord

what does the cerebellum do

coordinates movement, posture, balance, and muscle tone

what is arbor vitae

white matter

what are the meninges

dura mater, arachnoid mater, pia mater

what does the dural folds include

falx cerebri, tentorium cerebelli, falx cerebelli, and diaphragma sellae

how is cerebral spinal fluid produced

by the choroid plexus

how is cerebral spinal fluid reabsorbed

by the arachnoid granulations

what does the blood brain barrier depend on

capillary endothelial tight junctions with astrocyte support

what is CN I

olfactory

where does CN I pass through

the cribriform plate

what is CN III

oculomotor

what does CN III supply

most extraocular muscles

what is CN V

trigeminal

what does CN V supply

facial sensation and mastication; the largest cranial nerve

what is CN X

vagus

what does CN X provide

parasympathetic innervation to thoracic and abdominal viscera

where does the spinal extend from

the foramen magnum to approximately L1-L2

what anchors the spinal cord

filum terminale

what is the tapered end of the spinal cord called

conus medullaris

what does the cauda equina consist of

descending lumbar and sacral nerve roots

what supply the limbs

cervical and lumbosacral enlargments

what does epidural space contain

fat and blood vessels

what does subrachnoid space contain

cerebrospinal fluid and is used for lumbar puncture

what does gray matter form

posterior sensory horns, anterior motor horns, and lateral autonomic horns

what does the gray commissure surround

central canal

what does white matter form

anterior, lateral, and posterior funiculi carrying ascending and descending tracts

how many pairs of spinal nerves are there

31

what does the posterior root carry

sensory fibers

what do anterior roots carry

motor fibers

what does the posterior root ganglia contain

sensory neuron cell bodies

what does the anterior rami form

cervical, brachial, lumbar and sacral plexuses

what does the thoracic anterior rami form

intercostal nerves

what is the largest nerve in the body

sciatic nerve

reflex arc

receptor, sensory neuron, integration center, motor neuron, effector

what is stretch reflex

its monosynaptic and maintains muscle length

what is golgi tendon reflex

its polysynaptic and prevents excessive muscle tension

what is dermatomes

skin regions supplied by one spinal nerve