EXAM 3 PHYSIOLOGY

3 general functions of the nervous system:

-collects info (receptors in skin blood vessels)

-processes (brain and spinal cord)

-initiates a response (muscle contraction, endocrine system)

neurons:

basic structural and functional unit of NS

respond to stimuli, physical or chemical and sends signal to effectors

(eating, walking and thinking)

neurological cells:

provide homeostatic support

far MORE than neurons (5 to 1 ratio)

central nervous system:

brain and spinal cord

receive, process and respond to information

peripheral nervous system:

nerves that branch out from the brain and spinal cord

(forms the communication network between the CNS and related body parts)

sensory nervous system (INPUT)

-somatic sensory

-visceral sensory

motor nervous system (OUTPUT)

-somatic motor

-autonomic motor

somatic sensory

CONSCIOUS detection of mechanical stimuli (sound, smell, light touch, vibration)

and painful stimuli and temperature

visceral sensory

UNCONSCIOUS, monitor the internal environment

blood vessels and chemoreceptors

autonomic motor

regulates involuntary processes (UNCONSCIOUS) (heart rate, blood pressure, respiration and digestion)

somatic motor

VOLUNTARILY controlled

skeletal muscle, body movement etc.

Epineurium:

outermost sheath of the peripheral nerves (cushions it)

surrounds entire nerve

Perineurium:

connective tissue surrounding the fascicles

Endoneurium:

connective tissue that surrounds individual neurons and axons

dendrites

receives messages from other cells (like tree branches) and sends them to cell body

cell body

spherical part of the neuron that contains nucleus

(contains many organelles)

axon

large projection off of cell body

carries nerve impulses away from the cell body (soma)

Pseudounipolar:

single short process off of the cell body

ALL sensory neurons

Bipolar:

two projections off cell body

UNCOMMON, found in eye and nose

Multipolar:

several processes off cell body (MOST COMMON, motor neurons)

sensory neurons:

sensory input→ CNS

motor neurons:

output→ CNS

interneurons:

in CNS

connect spinal motor and sensory neurons, and transferring signals between sensory and motor neurons

resting membrane potential:

establishes electrochemical gradient, more negative inside than out, (more sodium outside than in)

-70mV, (-50 to -100 mV)

cell membrane is____

more permeable to K (potassium) than other ions

negative macromolecules and phosphates inside

receptive segment

cell body

binding of neurotransmitter released from presynp. neuron, production of graded potentials

initial segment

initiation of action potential

conductive segment

propagation of action potential

transmissive segment

action potential causes release of a neurotransmitter

excitatory post-synaptic potential

1. neurotransmitter binds to receptors which are chemically gated ion channels

2. ion channels open, letting sodium in, and potassium out

3. membrane potential depolarizes, becomes more (+)

4. SMALL in amplitude, short duration

   referred to as “graded amplitude”

inhibitory post-synaptic potential

1. neurotransmitter binds to ligand channel

2. chloride enters cell, becomes more (-)

3. away from threshold, called inhibatory

4. small amplitude, short duration

   referred to as “graded potential”

spatial summation

MANY synapses bring the membrane potential to the threshold

one EPSP could NOT do it alone

temporal summation

ONE synapse brings membrane potential to threshold RAPIDLY (excitatory)

one EPSP would NOT do it alone

depolarization:

gain of positive charge as sodium rushes in through the voltage gated channels

repolarization

return to negative potential as potassium rushes out of the cell through voltage gated ion channels

absolute refractory period

depolarization (sodium channels are open)

repolarization (potass. channels are open)

relative refractory period

potass. channels staying opens leads to hyperpolarization

the action potential _____

conducts action potentials

propagation

action potential, impulse or nerve signal

hyperpolarization

when voltage gated potass. channels stay open longer than the time needed to reach the resting membrane potential (the membrane pot. is lower than the resting potential, -70—> -80)

continuous conduction

unmeliynated axon (AP moves slower)

saltatory conduction

mylienated axon (AP moves much faster)

results in electrical insulation

nodes

where voltage gated ion channels are located

responsible for depolarization and repolarization

WHERE ACTION POTENTIAL OCCURS

local currents

small current around the myelin sheath (AT NODES)

movement of charge generating a current to rapidly depolarize and repolarize the membrane

angelo molosso

increased activity in the brain results in increased blood flow to the brain to support the increased neural activity.

adult human brain is about size of a _____

grapefruit & weighs 3 pounds

the larger the brain____

the more neurons

gyri

ridges

sulci

depressions between ridges

fissures

deep sulci

anterior

rostral

posterior

caudal

cerebrum

superior (largest portion of brain, all intellectual thinking goes on here)

diencephalon

-epithalamus

-thalamus

-hypothalamus

brain stem

-midbrain

-pons

-medulla

cerebellum

all the way in the back, and most inferior

sulcus

central

lateral

longitudinal

frontal lobe

largest lobe of cerebrum (motor function)

anterior to central sulcus

superior to lateral sulcus

decision making, concentration, planning etc.

parietal lobe

post central gyrus— posterior to the central sulcus

primary somatosensory coretx

fontal lobe and parietal lobe are divided by______

central sulcus

pre-central gyrus

primary motor cortex

association areas of the brain, voluntary movement

post central gyrus

posterior to central sulcus

primary somatosensory cortex (gen. sensory input skin & joints)

temporal lobe

inferior to lateral sulcus

primary auditory cortex & olfactory cortex (smell)

primary auditory cortex

hearing, smell and some vision

store auditory and visual memories

primary somatosensory cortex

general sensory input

sensory input from skin, joints

auditory cortex

involved in processing, hearing, smell and some vision

stores auditory and visual memories

occipital lobe

most posterior

primary visual cortex- processing visual input, coordinating eye movements

cerebrum: insular lobe

deep to temporal lobe and lateral sulcus

primary gustatory cortex

primary gustatory cortex

smell, taste, hearing, inputs from visceral organs

gray matter:

cell bodies and dendrites

white matter:

myelinated axons

white matter tracts:

large bundles, span longer distances

used to connect the right and left hemisphere by the corpus colossum

gray matter is on the outside of the brain called ____

cerebral cortex or “brain bark”

cerebral lateralization

one hemisphere of the brain is slightly specialized for certain functions compared to the other hemisphere

left hemisphere (analytical, reasoning)

“categorical”

verbal, speech

right hand control

right hemisphere (representing something)

“representational”

music/artistic ability

recognition of faces

left hand control

electrocephelography

measures brain activity

REM sleep (and 4 stages)

homeostasis

the process of maintaining internal stability while adjusting to changing external conditions

autonomic nervous system (ANS)

visceral sensory inputs, BELOW conscious level

2 divisions: parasympathetic and sympathetic

functions to maintain homeostasis

PNS

originates in brain stem and S2-S4

LONGER axon

myelinated

localized, hits 1 or 2 effectors

“rest and digest”

SNS (sympathetic)

SHORTER axon, and a-lot of branching (hits more effectors)

more mass action

myelinated

“fight or flight”

brainstem conatins:

major NS reflex centers

hypothalamus

integration and command center for autonomic functions & emotions

spinal cord

contains ANS reflex centers for defecation and urination

cranial nerve 10:

vagus nerve

origin of sympathetic nervous system:

thoracic and lumbar region

doesn’t immediately activate everything “Fight or Flight”→ tailored to the effector

autonomic tone

neurons are continuously releasing a neurotransmitter onto effectors

dual innervation

organ receives input from both SNS and PSNS

(2 divisions have antagonistic and cooperative effects)

antagonistic effects

2 divisions OPPOSE each other

para symp. slows heart rate, symp. increases it

blood vessels are innervated by:

sympathetic NS (vasoconstriction)

heart is dual, blood vessels are single innervation

the eye is controlled ONLY by:

PSNS

(single innervation)

transducers:

CONVERTS stimulus energy into electrical energy

(receptors are an example of this)

modality gated channels

respond to their type of stimulus

receptive field

distribution area of the endings of a sensory neuron

(how much area is that sensor detecting?)

hands have small field (more sensitive), back has a big field (less sensitive)

sensation

stimulus we are consciously aware of

to enter consciousness, must enter cerebral cortex

chemoreceptors

chemicals

mechanical receptors

mechanical

photoreceptors

photons (light)

thermoreceptor

cold and hot (temperature)

nicoreceptor

pain (tissue damage)