AGR 282 - Overview of the Nervous System and Supporting Cells

What is the major function of the nervous system

maintain homeostasis

sensory input

when the body receives signals from senses (information)

what is the functional cell of the nervous system

neuron

What body parts interpret information

brain and spinal cord

what are the 3 major components of the nervous system

sensory input, integration, and motor output

What do afferent neurons do?

receive info from the body

integration

gets information and has to decide what to do with it

what body parts have to do with integration

the brain and spinal cord

motor output

the response what the brain and spinal cord decided to do about the information

what do efferent neurons do

tells the body what to do (how to moved based on what the brain/spinal cord said)

what kind of communication does neurons use

fast, direct communication

what are the 3 key traits/jobs of neurons

transmit electrical impulses, respond to stimuli, and have a long life span

why are dendrites and axons long

because they need to travel long distances in order to get close to the cell they want to directly communicate with

what are the three parts of a neuron

soma, dendrite, axon

what is a soma

the cell body, has most of the organelles and the nucleus

what is a dendrite

branches off the soma that receive signals or sense, they are being stimulated by other neurons

what is an axon

the sending end of the neuron that allows for electrical communication

where does the axon orginate

the axon hillock

what is the significance of the axon hillock

it is where the axon meets the stoma which allows it to decide whether a signal is strong enough to send to the next cell or not

what is the axon terminal

the end of the axon that communicates with the next cell

why does the axon have a hard time repairing itself

because it doesn't have a way to make proteins

what organelles do the axons have

lysosomes and the mitochondria

what is the significance of the axon branching

it means one axon can stimulate multiple cells at one time

what happens if an axon is thick

signals can be sent faster

synapse

where the axon meets with the target cell

what are the 3 parts of a synapse

axon terminal, synaptic cleft, and postsynaptic cell

synaptic cleft

space between the axon and the other cell

postsynaptic cell

dendrite of another axon or another cell

what do synaptic vesicles release

neurotransmitters

neurotransmitters

small chemicals similar to hormones that bind to a receptor on a target cell and cause some sort of action by that cell

what does the myelin sheath do

protects and insulates the axon

how does the myelin sheath help with signal speed

speeds up electrical impulses (action potentials)

what forms the myelin sheath

supportive cells

afferent neurons

sensory neurons that receive info from the body and send it to the brain and spinal cord where it can be dealt with

efferent neurons

motor neurons that take instructions from the brain and spinal cord and send it into the body

where is the stoma of efferent neurons located

in the brain or spinal cord which means there is a really long axon

interneurons

most of the neurons in the body that connect afferent neurons to efferent neurons

what is the main role of interneurons

connect and interpret

what neuron plays a big role in reflexes

interneurons

what are the 2 major divisions of the spinal cord

central nervous system and peripheral nervous system

what is the central nervous system composed of

the brain and spinal cord

what is the main function oft he central nervous system

integrate information from afferent neurons

what kinds of neurons is the central nervous system made up of

mostly interneurons but also afferent and efferent

what is the peripheral nervous system made of

peripheral nerves (bundles of neurons) and everything but the brain and spinal cord

what is the main function of the peripheral nervous system

to communicate

what kinds of neurons make up the peripheral nervous system

afferent and efferent neurons

what are the 2 divisions of the peripheral nervous system

somatic and autonomic

autonomic nervous system

no thought/unconscious control (heart beat)

somatic nervous system

voluntary control (skeletal muscle)

what does the autonomic nervous system break down into

sympathetic and parasympathetic

sympathetic

fight or flight

parasympathetic

rest and digest

nervous system breakdown

what cells compose 90% of the nervous system

supportive cells

what are neuroglia

supportive cells

what is the function of supportive cells

support, protect, and give nutrients to neurons

true or false: the central and peripheral systems have different supportive cells

true

what are the 4 supportive cells in the central nervous system

ependymal cells, astrocytes, oligodendrocytes, and microglia

what is the function of ependymal cells

produce and regulate cerebrospinal fluid

where are ependymal cells located

they line the ventricles of the brain and spinal cord

what helps ependymal cells circulate cerebral spinal fluid

cilia

why do ependymal cells have tight junctions

to regulate the movement of cerebrospinal fluid

what is the most abundant support cell

astrocyte

what is the function of the astrocyte

secrete chemicals to cause the capillaries to form tight junctions, which regulates what goes in and out of the brain and spinal cord

when astrocytes form tight junctions, what do they create

the blood brain barrier

how do astrocytes form the blood brain barrier (other than tight junctions)

release chemicals and control the chemical environment surrounding neurons

what is the function of the blood brain barrier

prevent the passage of molecules into the central nervous system from the blood

how do molecules get past the blood brain barrier

lipid soluble molecules can cross and everything else has to be carried via proteins

what is the function of oligodendrocytes

produce the myelin sheath around the axons of some neurons

how do oligodendrocytes form the myelin sheath around axons

they have arms that wrap around the axons

what is the function of microglia

to attack/eat invading organisms and dead cells

what are considered to be the immune systems of the central nervous systems

the microglia

why do the microglia need to eat pathogens

because white blood cells have a hard time getting past the blood brain barrier, so we need a different clean up crew

what are the two support cells of the peripheral nervous system

satellite and schwann cells

what is the function of satellite cells

don't know but think they provide nutrients

where are satellite cells located

surrounding the neurons

what is the function of schwann cells

form the myelin sheath on axons in the PNS

what is the difference between schwann cells and oligodendrocytes

oligodendrocytes have arms that wrap and schwann cells wrap themselves around

what are the 2 parts of the central nervous system

brain and spinal cord

what are the 2 types of matter in the brain

gray and white

what is grey matter

pink tissue that has the soma, dendrite, and axon terminals

what happens in the gray matter

receive signals and where cell to cell communication actually takes place

what is white matter

white tissue that contains the majority of axons

what happens in white matter

axons are flowing together and traveling from one place to another

what are the parts of the brain

cerebrum, cerebellum, ventricles, limbic system, midbrain, pons, medulla oblongata

what part of the brain is the bulk of the brain

the cerebrum

what part of the brain aids in function

cerebellum

what are ventricles

fluid filled cavities

frontal lobe

what is the function of the frontal lobe

reasoning, movement, emotions, memory, problem solving, INTELLIGENCE

parietal lobe

what is the function of the parietal lobe

sensory motor complex, motor output, movements, orientation, receive stimuli

temporal lobe

what is the function oft he temporal lobe

auditory processing and speech

occipital lobe

what is the function of the occipital lobe

visual processing

how is the cerebrum divided

into two hemispheres

what connects the 2 halves of the cerebrum

corpus callosum

what is the corpus callosum

white matter that is the relay center between the 2 halves of the brain that has no signaling

what side of the brain is the science side

left