Nervous System

Brain and spinal chord.

cranial nerves, spinal nerves, sensory receptors, ganglia, somatic nervous system, sensory receptors, enteric nervous system, and autonomic nervous system.

Maintain homeostasis and integrate all body activities.

Cell body, nissl bodies, dendrites, axon, and axon hillock.

Multipolar(several dendrites and one axon), bipolar(one dendrite and one axon), and unipolar(one process arising from the cell body that branches into two axon-like processes).

Sensory neurons, motor neurons, and interneurons.

Astrocytes(helps form blood brain barrier), Oligodendrocytes(produces myelin sheath), microglia(carry on phagocytosis) and ependymal cells(produce cerebrospinal fluid and line ventricles of the brain).

Schwann cells(Forms myelin sheath)

and

Satellite cells(provides structure, flat neuroglial cells that surround cell bodies of ganglia and exchange of material)

unmyelinated gaps that occur at intervals along an axon

Neurotransmitters bind to receptors and causes a voltage membrane difference by depolarization and re-polarization of the membrane potential.

• The graded or action potential at
• the end of the axon triggers the release of the neurotransmitters into the synaptic cleft

One contains and myelin sheath and the other doesn't

CNS and PNS

Sub divisions of the pns and functions

-somatic nervous system (sns) voluntary:controls the skeletal muscles(motor)

Automatic nervous system (ans) involuntary: affects the heart  and digestive system(motor)

Enteric nervous system (ens) involuntary

• Nervous tissues are designed to
• transmit electrical impulses and includes:

o    cell body--analyzes incoming information

o    dendrites--receives incoming information

o    axon--transmits information to other cells

• o    neuroglia cells--protects,protects and
• nourishes the neurons

• o   myelin sheath--allows axons to send faster
• signals

o    terminal--synaptic ends

wrap around axons

opening or cloosing of ligand-gated and mechanically gated channels in response to a stimulus

Responds to environmental stimulus

impulses from a neuron to another cell through a synaptic cleft

a stimulus that is just strong enough to depolarize the membrane to threshold.

One carries impulses away from a synapse and the other carries an impulse toward a synapse

impulses that conduct directly between the plasma membranes through gap junctions

EPSP is a depolarizing postsynaptic potential and IPSP is a hyperpolarizing postsynaptic potential

Evironmental stimulus initiates sensory neurons

neuro transmitters initiates interneurons

neuro transmitters initiates motor neurons

Any stress that changes a controlled condition, excites a sensory receptor, muscle or nueron

Once threshold depolarization occurs, voltage-gated channels open, and an action potential that is always the same size occurs

• Comes from a electrical voltage, When the membrane sees no
• action potentials and remains at a constant -70 mv

• Depolarization-when a response makes the membrane less polarized(inside less negative)
•  The first stage of
• an action potential where voltage gated Na+ channels quickly open and sodium rushes into the cell, making the inside of the cell more positive than the resting membranes potential.

Action potentials-rapid electrical events occurring in two phases:depolarizing phase and repolarizing phase.

Graded potentials-the opening or closing of ligand-gated and mechanically gated channels in response to stimuli

A wave of depolarization and repolarization that self-propogates along the plasma membrane of a neuron

Repolarization-When the restingmembrane comes back to a resting state  of -70mv. Na+ and K+ are at equallibum

Hyperpolarization- when a response makes the membrane more polarized(inside more negative)where voltage gated K+ channels open and potassium goes out of the cell, making the outside become more negative than the resting membranes potential.

• Graded potentials are: 
• stimulated by sensory neurons, occur in the dendrites, weak potentials, communicate with other close neurons, may or may not cause a change in the membrane, has ion gates that open one at a time, unless there is a strong stimulus then all open to cause an action potential

• Action potentials are: all or none potential, impulses are strong enough to cause change
• in the membrane, has voltage gates that allow Na+ to enter and K= to exit the neuron

• Motor neurons:
• Sympathetic nervous system --controls the activity of the heart (fight orflight)Parasympathetic nervous system---controls the body for rest and repair

• Membrane resting state of -70 mv
• sensory receptors detect an environmental stimuli at the
• dendrites as graded potential

graded potential nerve impulse travels down the neuron as neurotranmitters exit through the synaptic cleft.

• neurotransmitters receptors receive the chemical stimuli if the chemical stimuli is strong membrane threshold will be
• met -70mv to -55mv 

• Na+ voltage gates open allowing Na+ to rush into the cell
• depolarization occurs
• ***action potential*** 
• Na+ gates close

• k+ ion gates open allowing it to exit the cell
•  repolarization of the membrane
• sodium/potassium pump begins to pump 3 Na+ ions out of the
• cell and 2 k+ ions back into the cell 

cell returns to a resting state of -70 m

A neuron has an electrical and chemical gradient across its outer cell membrane.

More positively charged Na+ on the outside of the membrane and more negatively charged on the inside K+ of the membrane, because of the sodium/potassium pump,that moves 3 Na+ ions out for every 2k+ ions moving in.