Physio Exam 2

CNS

brain and spinal cord

afferent

input to CNS from periphery (goes to brain)

efferent

output from CNS to periphery (goes to body)

glia cells

support cells of the brain

aid and modulate neuron’s activities

1-5 trillion

astrocytes

most abundant glia

synthesize and regulate NT levels, provide nutrients to neurons (glucose, lactate)

ionic balance (K and Ca ions)

repaire injury

maintains BBB

Oligodendrocytes

provide support

insulate the axons of the CNS through myelination

schwann cells

myelinate PNS neurons

microglia

immune defense - suppress inflammation

scavenge dead neurons, plaques, pathogens

ependymal cells

epithelium-like lining of ventricular system

have cilia/microvilli/choroid plexus

cilia

circulate CSF around CNS

microvilli

absorb CSF

choroid plexus

a population of modified ependymal cells and capillaries to make CSF

protection of CNS

1. bone (skull)
2. cranial meninges
3. CSF

dura mater

“tough mother” inelastic

arachnoid mater

“spiderlike” layer connects to pia

pia mater

most delicate that’s like shrink wrap around your brain

CSF

the cushion of the brain. similar density as the brain which allows our brains to float in the skull

BBB

capillaries lined with epithelial cells that form tight junctions

limits what can get into brain, prevents certain drugs, toxins, and pathogens (viruses, bacteria) from getting access

selective nature

anterior

rostral

posterior

caudal

superior

dorsal

inferior

ventral

white matter

myelin sheaths and axons

gray matter

cell bodies and soma

lobes of the brain

1. temporal lobe
2. frontal lobe
3. parietal lobe
4. occipital lobe

Parietal lobe

somatosensory processing (touch, proprioception, pain)

plasticity

forming new connections between neurons

frontal lobe

1. prefrontal cortex
2. primary motor cortex


1. premotor cortex

prefrontal cortex

executive functions (abstract thinking and planning, judgement, social behavior)

mental processes

primary motor cortex

innervates skeletal muscle

commands facial and tongue muscles to speak wordss

premotor corex

integration of sensory information to motor cortex. fires before primary cortex

phineas gage

rod went through left frontal lobe affecting personality and behavior (led to understanding that frontal lobe controlled/suppressed behavior)

Temporal lobe

hearing

language perception

complex aspects of vision-object recognition

primary auditory cortex

perceives sound

broca’s area

programs sound and pattern of speech

wernicke’s area

plants content of spoken words

angular gyrus of parietal-temporal-occipital association cortex

integrates sensoryinput

primary visual cortex

perceives sight

occipital lobe

primary visual cortex

processes visual input

damage can result in cortical blindness

hippocampus

learning and memory

amygdala

fear, emotion, stress

cingulate gyrus

emotions, executive function

thalamus

relay station (signal in and out of brain)

hypothalamus

the 4 Fs

fighting, felling, feeding, mating

olfactory bulb

smell

Short-term memory

immediate storage

retained seconds to hours

limited capacity

rapid retrieval

permanently forgotten unless consolidated into long-term

stored by transient modifications in functions of preexisting synapses

long-term memory

stored later on (must be transferred from short term through practice

retained for days to years

very large capacity

slower retrieval (ingrained memories are rapid)

relatively stable memory retrieval

stored by permanent functional/structural changes b/w existing neurons (new synpases) synthesis of proteins plays a role

tectum

superior colliculi (vision)

inferior colliculi (hearing)

produce orienting movements to sight and sound

tegmentum

ventral part of midbrain

periaqueductal gray (pain)

substantia nigra (movement)

ventral tegmental area (reward)

pons

bridge

wakefulness, arousal, sleep, breathing

medulla

vital functions

breathing, heart rate, coughing

cerebellum

coordinated movement, fine motor control, balance, posture

purkinje cells

midbrain

tectum and tegmentum

hindbrain

pons

medulla

cerebellum

spinal cord

relays information to and from the body and brain (motor out sensory in)

serves as mini-brain for some reflexes

dorsal horn

receives sensory info

afferent

grey matter

lateral horn

sympathetic division of the autonomic nervous system

efferent

grey matter

ventral horn

sends motor output

efferent

grey matter

interneurons

relay sensory information to motor neurons. mostly comprise the gray matter in the spinal cord

dorsal root ganglia

cell bodies of the sensory neurons

reflex arc

sesnory receptor sends information through sensory neuron to the dorsal root ganglion into the dorsal root through the internuron thro

stimulus

change detectable by the body (exist in various modalities)

photoreceptors

detect light

mechanoreceptors

detect vibrational change

thermoreceptors

detect temperature change

nociceptors

detect pain

osmoreceptors

detect changes in salt concentration

chemoreceptors

detect chemical changes

tonic receptor

slow adapting

providing constant information

ie muscle stretch receptors

phasic receptor

rapid adapting and off response

signaling change in stimulus intensity

ie pacinian corpuscle

receptive field

region of stimulus detection for a given receptor

acuity

closer the receptors = smaller receptive fields = greater acuity

lateral inhibition

sharpens contrast by inhibiting activity of neighboring receptive neurons

touch

conscious perception of contact

active touch

you touching something (physically directing the contact)

top down processing

top down processing

you seek info and you control what occurs (your brain tells your fingers where to move and how to touch)

passive touch

someone os something else touches you (the action of you responding to touch)

bottom-up processing

bottom up processing

you react to an external stimuli (you are responding, it touches your hand and goes up to your brain and then responds)

spike train

representative of action potentials that shows spikes based off what receptor you’re looking at

receptors near epidermis

* very tiny receptor fields
* sensitive
* responds more to edges

receptors deeper in dermis

* larger receptor fields
* respond more to vibrations

Type I cutaneous mechanoreceptor

superficial and fine touch

Merkel Disk and Meissner Corpuscle

Merkel Disk

edges, points

slow adapting (SA1)

Meissner Corpuscle

lateral motion

rapid adapting (RA1)

Ruffini ending

skin stretch

slow adapting (SA2)

Pacinian Corpuscle

vibration

rapid adapting (RA2)

greater acuity

smaller receptive fields

somata in sensory neurons

outside the spinal cord in the dorsal root ganglion

tactile information

processed in central touch system

enters the somatosensory cortex (S-1)

neocortex layers 2,3

intracortical connections

neocortex layer 4

thalamic input

neocortex layer 5

output to subcortical structures

neocortex layer 6

output to thalamus

neocortex skin receptors

enter in 3b project to 1

neocortex proprioception/muscle

enter in 3a projects to 2

neocortex all 4 areas

project to secondary somatosensory cortex and association cortex (5+7)

emergent properties of area 2

convergence of three presynaptic neurons with similar arrangement allows direction and orientation selectivity

downward cortical processing

produces strong excitatory response because the presynaptic neurons are contact simultaneously

upward cortical processing

strongly inhibits firing because it enters all three inhibitory fields first. neuron responds poorly to upward motion through the excitatory field because the initial inhibitions outlasts the stimulus