A&P 10

• sensory-receiving stimuli
• integrative-deciding how to respond to stimuli
• motor-carry out response to stimuli

• made up of:
• neurons-nerve cells
• neuroglial cells-neuroglia, glia
• connective tissue
• blood vessels 

react to physical and chemical changes in their surroundings 

receive the input

nerve fiber, carries the information away from the cell in the form of impulses

small space between a neuron and the cell with which it communicates

messenger molecules that convey neural information 

brain and spinal cord, composed of nerves

• picks up information and delivers to CNS
• -provide sensory function
• -detects changes inside and outside the body
• -external environment

• carry out the motor function of the nervous system
• -muscles and glands; controlled by nerve activity 

• motor function
• -voluntary
• -skeletal muscles, causing contraction 

• motor function
• -involuntary subconscious actions
• -smooth muscle
• -endocrine 

• connect the central nervous system to other body parts
• -cranial 
• -spinal

extends into the axon and supports it

• consists mainly of rough endoplasmic reticulum
• -scattered throughout the cytoplasm
• -membranous packets

• encase the large axons of peropheral neurons 
• -wrap around the axon
• -create myelination
• -speed neurotransmision

• creates faster travel than if unmyelinated
• encases the axon

narrow gaps in the myelin sheath between schwann cells (slower travel)

• myelinated axons
• faster travel

• unmyelinated axons
• slower travel

• nerve re-generation
• only in schwann cells/PNS
• case around myelination
• cytoplasm

• has many processes arising from its cell body
• -only one is an axon; the rest are dendrites 
• -brain or spinal cord

•  has only two processes
• -one is an axon and the other is a dendrite 
• -eyes nose and ears

• single process extending from cell body
• -two branches which really function as a single axon
• -projection
• -ganglion
• -sensory neurons

• outside the brain or spinal cord
• -cell bodies of some unipolar neurons aggregate in specialized masses of nerve tissue

• afferent neurons 
• -from peripheral body parts into the brain or spinal cord
• -sensory receptors, detecting changes in the outside world

• lie within and form links with other neurons
• -may direct incoming sensory information to appropriate region for processing and interpreting

• efferent neurons
• -multipolor and conduct impulses out of the brain an spinal cord to effectors
• -somatic nervous system

• star-shaped cells between neurons and blood vessels 
• -cns
• -formation of scar tissue
• -blood barrier
• -structural support
• -communicate with one another and neurons

• in rows along axons
• -myelination 
• -cns
• -produce nerve growth factors 

• -cns
• -small cells with few cellular processes
• -phagocytosis
• -structural support

• -cns
• -in the lining of the ventricles (cavity) of the brain and central canal of the spinal cord
• -forms a porous layer through which substances diffuse between the interstitial fluid of the brain and spinal cord

• surround cell bodies of neurons in ganglia
• -pns

• -site of injury
• -distal portion of axon degenerates 
• -proximal end of injured axon regenerates into tube of schwann cells
• -schwann cell tube extends distal to the injury
• -schwann cells form new myelin sheath
• -former connection reestablished 

neuron carrying an impulse to the synapse is the sender

the neuron receiving the input at the synapse 

is positively charged

is negatively charged

• 1. depolorization- Na+ channels open
• -drop resting potential to -55mV(threshold stimulus)
• -na rushes in

• 2. repolorization 
• -k+ channels open 
• -K+ flow

lasts about 1/2500 seconds, the axons voltage-gated sodium channels are not responsivee at all, axon cannot be stimulated 

during the time when the membrane reestablishes its resting period 

• action potentials appear to jump from node node
• impulse conduction

• changes in chemically gated ion channels create local potentials
• -enable one neuron to affect another

of the excitatory and inhibitory effects of the postsynaptic potentials commonly takes places at the trigger zone 

if the net effect is excitatory, but subthreshold, an impulse will bot be triggered, but another immediate release of neurotransmitter will be more likely to bring the postsynaptic cell to threshold

• axons originating from different parks of the nervous system leading to the same neuron
• -allows the nervous system to collect, process,  and respond to information
• -may reflect summation of input from two sources

• -single axon, but axons may branch at several points
• -reaching other neurons
• -info can be processed and evoke a response

• neurons completely within the cns
• receives input from neurons
• each pool generates output 

• neurons in the brain and spinal
• -substances that alter a neurons response to a neurotransmitter or block the release of a neurotransmitter