Being complex organisms humans and other eukaryotes have not one multiple cells, but the cells are specialized and vary greatly in size, shape, color, ability and function (like pikmen).
The cell body is a "normal cell" it has a nucleus, mitochondria and other organelles.
is elongated nerve fiber of the nerve cell that extends from the cell body to the terminal branches.Most neurons have only one.Conducts electrical impulses away from the cell body (soma).Transmit information to different neurons, muscles, and glands.Larger the size, the faster the transmission of information (signals).Some are covered with myelin sheath that works as an insulator which increases the transmission of information
secretory regions of nerve.
are branched extensions of cell body of the nerve cells.Treelike roots.Most neurons have many, some have only one.Increases the surface area of the cell body.Receive information from other neurons and transmit electrical stimulation to the soma (cell body).
Pre-synaptic cell (delivering end)
1. Neurotransmitter: chemical messenger that carries signals between neurons and other cells in the body – is synthesized and sent down the axon 2. Action potential causes calcium channels to open and neurotransmitters are released into the synaptic cleft
Post-synaptic cell(receiving end)
1. Neurotransmitter from the synaptic cleft binds to the receptors on the post-synaptic cell which either excites or inhibits depending on the information 2. Any left over neurotransmitters is taken back into pre-synaptic cell
Wraps around the axon intermittently (not continuous).Gaps between adjacent Schwann cells are known as nodes of Ranvier.Fatty substance
Presynaptic cell (delivering end)
1. Neurotransmitter.Chemical messenger that carries signals between neurons and other cells in the body.There are various types of neurotransmitters including.Aspartate, Glutamate, Acetylcholine, Dopamine, Norepinephrine, Epinephrine, and more that bind to different receptors.Synthesized and sent down the axon 2. Action potential causes calcium channels to open and neurotransmitters are released into the synaptic cleft
Postsynaptic cell (receiving end)
3. Neurotransmitter. From the synaptic cleft binds to the receptors on the postsynaptic cell which either excites or inhibits depending on the information 4. Any left over neurotransmitters is taken back into presynaptic cell or enzymatically broken down
Part of glial cell.Makes myelin sheath in the peripheral nervous system (PNS) by wrapping around the axons of motor and sensory neurons.Found in PNS
the central nervous system analogue of Schwann cells, makes myelin sheath around CNS axons.Found in CNS.
Nodes of Ranvier
Gaps where there is no fat on an axon, allowing the electrical signal to travel (since fat/myelin sheaths block the signal).
A small gap between two neurons cells that allows one neuron to send information to another
Provide insulation to neurons in the peripheral nervous system (PNS)
Digest parts of dead neurons
Star shaped cell,Provide physical and nutritional support,Clean debris,Transport nutrients to neurons,Hold neurons in place,Digest parts of dead neurons,Regulate content of extracellular space
➙ action potential jumps from one node of Ranvier to the next ➙ speed of conduction is faster.Action potential cannot propagate in myelinated segments.Current is carried by node of Ranvier instead
3Na+ out and 2K+ in, leaves - charge inside, + charge outside. K+ can leak out, but Na+ cannot leak in supporting the - charge inside, + charge outside.
refers to sodium and negative charge outside the cell, potassium and positive charge inside the cell
Stages of an action potential
Resting, Depolarization, Repolarization, Hyperpolarization, & Refractory period
cell at rest, sodium potassium pump on, -70 mV, sodium outside, potassium inside, ion channels are closed.
sodium channels open, positive sodium rushes inside, membrane potential becomes +30 mV, lots of sodium and potassium inside.
potassium channels open (positive potassium rushes outside), sodium channels close (lots of sodium inside), this is opposite of the resting state.
membrane potential drops below normal level.
the sodium potassium pump reestablishes the resting state, the neuron can not generate another action potential until the cell goes back to the normal -70 mV.
response means that if a stimulus meets the minimum threshold it will cause the same response as any greater stimulus.
moves 3 sodium outside and 2 potassium inside keeping the cell negative on the inside (negative membrane potential).
cause nerves to send a signal (membrane -)
fibers prevent the signal (membrane +).
receptor binding causes postsynaptic potential to be more positive (depolarization) = if it gets above threshold, action potential results.
receptor binding causes postsynaptic potential to be more negative (hyperpolarization) = makes it more difficult to reach threshold.
two or more nerves firing at the same time.
Multiple signals near each other in TIME are added together
Multiple signals near each other in SPACE are added together
Also known as neuroglia,Supportive cells in the central nervous system (CNS),Supportive – do NOT conduct electrical impulses.Instead, surround and provide support for and insulation between neurons.Most abundant cell types in the CNS.