Control and Coordination

function of the nervous system

oversees communication among the organ systems

sensory input

recieves stimuli via sensory receptors

integration

processes the input stimuli, decides what to do

motor output

activates the effector organs to cause a response

neurons (nerve cells)

excitable cells that respond to stimluli by conducting impulses to transmit signals

neuroglia (glial cells)

supportive cells that provide nutrition, insulation, and help with signal transmission

astrocyte

subtype of glial cells

oligodenrocyte

creates the myelin sheath that insulates axonsregul

microglia

regulate brain development, maintenance, and repair

schwann cells

glial cells that form the myelin sheath on axons outside the brain

they engulf a segment of the axon

soma

contains nucelus and most organelles

processes

extensions from the cell body

dendrites

main receptor of signals (input region)

axon

generates and transmits nerve impulses

conducting region

also known as nerve fiber

ganglion

collection of nerve cell bodies located in the body

nerves

bundles of axons that extend from the brain and spinal cord to the rest of the body

axon terminal

the end of the axon that releases neurotransmitters at a synapse when a nerve impusle is recieved

the secretory region

myelin sheath

covers long axons (nerve fibers) to protect and electrically insulte them to increase the speed of nerve impulse transmission

nodes of ranvier

unmyelinated gaps in the myelin sheath that aid in increasing the velocity of a nerve signal transduction

multipolar

meaning >3 processes

bipolar

2 processes, 1 axon and 1 dendrite

unipolar

1 process dividing from the cell body like a T

senosry neurons (afferent)

transmit info from sensory receptors (CNS)

most are unipolar

motor neurons (efferent neurons)

transmit info from the CNS to the rest of the body

most are multipolar to send impulses to many different places

interneurons

housed in the CNS and transport info between the sensory and motor neurons

organization of the nervous system

nervous sytem → PNS and CNS

PNS → sensory (afferent division) and motor (efferent division)

motor division → somatic and autonomic

autonomic → parasympathetic and sympathetic

central nervous system

brain and spinal cord

integration and control center

peripheral nervous sytem

spinal and cranial nerves

communication system between the cns and the rest of the body

ventricles

hollow fluid filled cavities within the brain that contain the chroid plexus

choroid plexus

makes cerebrospinal fluid

meminges

layer of tissue that protects the brain

cerebrospinal fluid

cushions the brain from injury

cerebrum

• largest part of the brain

• made of left and right hemispheres

• dividied into 4 lobes

• functions in learning, speech, emotion, reasoning, vision, hearing, and fine movements

• cerebral cortex is the surface and is arragned in folds to increase surface area

cerebellum

• maintains posture and blance

• coordinates patterns for smooth and agile subconcious movements

brainstem

• base of the cerebrumand anterior to the cerebellum

• includes the medulla obolongata, midbrain, and pons

• relays info between rest of brain and the spinal chord

• coordinates functions like respiration, circulation, body temperature, sleep, digestion, and swallowing

pareital lobe

helps integrate sensory input and processes language

frontal lobe

needed for memory, motivation, and porblem solving

temporal lobe

essential to language and speech

behind the ears

occipital lobe

visual processing center

limbic system

emotional center of the brain, controls things like moods and instincts

Na/K pump

moves 3 Na out of cell and 2 K into cell to maintain resting membrane potential of - 70 mv

voltage gated channels

open and close in response to changes in membrane potential

ligand gated channels

only open when a specific chemical lieka neurotransmitter binds to channel

mechanically gated channels

open if the membrane is stretched or physically deformed

threshold

the cell membrane reaches a specific threshold activating the action potential

depolarization

the sodium protein channel opens up and the sodium ions rush into the cell returning to 0 mv

overshoot

membrane potential becomes more positive and the sodium ion channel becomes inactivated

repolarization

the potassium channel opens up and potassium ions leave the cell

hyperpolorization

the potassiu chanel causes teh cell to be hyperpolarized and potassium ions close

excitatory neurotransmitters

open ion channels in the cell membrane and depolarize the postsynaptic neuron, causing an action potential to be passed along

inhibitory neurotransmitters

can hyperpolarize the postsynaptic neuron so it can’t send on teh action potential and thus the message isn’t passed on

sensory (afferent) division

sensory nerve fibers

recieves sensory stimuli to send back to CNS/brain

motor division

sends out information from teh brain to effector organs like muscles and glands

somatic nervous system

somatic motor nerve fibers

conduct impulses from cns to skeletal muscles

controls voluntary movements

autonomic nervous system

visceral motor nerve fibers

conduct impulses from CNS to smooth muscles, cardiac muscles, and glands

controls involunatry movements

acetycholine

neurotransmitter released to muscles to stimulate contractions

released in parasympathetic

norepinehrine

released in symphathetic nervous system

parasympathetic

craniosacral nerves (start at base of brain or just above tailbone)

ganglia are far from spinal cord or right next to/inside effector organs

calms you down, does the opposite of everything the sympathetic does

sympathetic

thoracolumbar nerves (start between thoracic and lumbar vertebrae)

ganglia are in the spinal cord and send signals far distances

excites you/amps you up

mechanoreceptors

mechanical force like vibration, pressure, stretch, and touch

thermoreceptors

change in temperature

photoreceptors

light

chemoreceptors

chemicals

nociceptors

pain

reflex

automatic reaction to stimuli

innate (intrinsic) reflex

a rapid, predictable motor resposne to a startling stimulus

learned (acquired) reflex

a response resulting from practice repetition or experience

5 components of a reflex arc

1. receptor

2. sensory neuron

3. integration center

4. motor neuron

5. effector

olfactory nerve

sensory

sends scent info from nose to brain

optic nerve

sensory

sends visual info from eyes to brain

oculomotor nerve

motor

controls the movement of 4 out of the 6 eye muscles as well as pupils reaction to light

trochlear nerve

motor

controls movement for an eye muscle

trigeminal nerve

both

largest nerve that has 3 main branches that innervate the face and jaw muscles

abducens nerve

motor

controls movement for an eye muscle

facial nerve

both

operates muscles for most facial expressions, taste buds, salivating

sends info from outer ear to brain

vestibulocochlear nerve

sensory

sends auditory info from cochlea to brain, key for hearing and balance

glossopharyngeal nerve

both

sensation, tase, swallowing

sends sensory info from sinuses to brain

vagus nerve

both

longest nerve

controls heart and digestive tract

accesory nerve

motor

controls muscles in the neck

hypoglossal nerve

controls most muscles in tongue so we can swallow and talk

sensing

sensory cells that translate stimuli into action potentials that our nervous system can integrate

general sensory receptors

modified nerve ending

touch

special senses

vision, smell, taste, hearing, and equilibrium

light

electromagnetic waves

photoreceptors

convert light energy into electircal energy that travel to the brain

eyebrows

keep sweat and sunlight out of the eyes

eyelids and eyelashes

trigger reflexive blinking to keep eyes moist

lacrimal apparatus

consists of the lacrimal gland that produces and secretes tears and the ducts that drain the secretions

extrinsic eye muscles

control the eye movements

superior oblique

depresses and turns eye laterally

superior rectus

elevates and turns eye medially

lateral rectus

lateral movement

medial rectus

medial movement

inferior rectus

depresses and turns it medially

inferior oblique

elevates and turns it laterally

fibrous layer

outermost layer of the eye

sclera

anchoring site for extrinsic eye muscles

cornea

window that lets light into the eye

vascular layer

middle layer of eye

choroid

supplies all the layers with blood