Maintain homeostasis and integrate all body activities.
What is a neuron contain?
Cell body, nissl bodies, dendrites, axon, and axon hillock.
What are the classified structures of neurons?
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).
What are the classified functions of neurons?
Sensory neurons, motor neurons, and interneurons.
What neuroglia is contained in CNS?
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).
What neuroglia is contained in PNS?
Schwann cells(Forms myelin sheath)
Satellite cells(provides structure, flat neuroglial cells that surround cell bodies of ganglia and exchange of material)
What are nodes of ranvier?
unmyelinated gaps that occur at intervals along an axon
What are neurotransmitters?
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
What is the difference between myelinated and unmyelinated
One contains and myelin sheath and the other doesn't
List the levels of organization of the nervous system with functions
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
List the histology of the nervous tissue
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
o terminal--synaptic ends
What structure does the myelin sheath have?
wrap around axons
What are graded potentials?
opening or cloosing of ligand-gated and mechanically gated channels in response to a stimulus
How does grade potentials begin
Responds to environmental stimulus
What is a chemical synapse?
impulses from a neuron to another cell through a synaptic cleft
What is a threshold stimulus?
a stimulus that is just strong enough to depolarize the membrane to threshold.
What are post-synaptic neurons and pre-synaptic neurons?
One carries impulses away from a synapse and the other carries an impulse toward a synapse
What is a electrical synapse?
impulses that conduct directly between the plasma membranes through gap junctions
What are Excitatory postsynaptic potential(EpSP) and Inhibitory postsynaptic potential(IPSP)?
EPSP is a depolarizing postsynaptic potential and IPSP is a hyperpolarizing postsynaptic potential
What initiates graded potentials in
sensory neurons, interneurons and motor neurons?
Evironmental stimulus initiates sensory neurons
neuro transmitters initiates interneurons
neuro transmitters initiates motor neurons
What is stimulus?
Any stress that changes a controlled condition, excites a sensory receptor, muscle or nueron
The action potential is an all-or-none
Once threshold depolarization occurs, voltage-gated channels open, and an action potential that is always the same size occurs
What is a Resting membrane potential?
Comes from a electrical voltage, When the membrane sees no
action potentials and remains at a constant -70 mv
What is Depolarization?
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.
What are action potentials and graded potentials?
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
What is a nerve impulse?
A wave of depolarization and repolarization that self-propogates along the plasma membrane of a neuron
What is repolarization?
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.
Compare graded potentials with action 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
What are the subdivisions of PNS?
Sympathetic nervous system --controls the activity of the heart (fight orflight)Parasympathetic nervous system---controls the body for rest and repair
Summarize the events that take place
during one action potential.
ions, ion channels, gates and neurotransmitters have in propagation of an action potential?
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
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
Describe the conditions that exist across the neuronal membrane during the resting state.
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.