ANPS - Neurons and Nervis System Basics

central nervous system

brain and spinal cord; integrative and control centers

peripheral nervous system

cranial and spinal nerves; communication between CNS and the rest of the body

sensory (afferent) division

somatic and visceral nerve fibers, impulses go from receptors to the CNS

motor (efferent) division

motor nerve fibers, impulses go from CNS to muscle/gland cells

somatic nervous system

voluntary, impulses CNS -> skeletal muscle

autonomic nervous system

involuntary, CNS -> cardiac or smooth muscle and glands

sympathetic division of autonomic system

mobilizes body during activity

parasympathetic division of autonomic system

conserves energy, promotes house-keeping functions during rest

neuron

basic unit of nervous system, excitable cells that transmit electrical signals, do not divide after fully mature

glia

non-excitable, primarily support and protect neurons, undergo mitosis throughout life

properties of neurons

excitable, conductive, extreme longevity, amitotic

cell body (soma)

enclosed by plasma membrane, contains cytoplasm and nucleus, biosynthetic center of the cell, chromatophilic substances, conducts electrical signals towards the axon

Nissl bodies/substances

collections of ribosomes in the cytoplasm of a neuron, stain dark purple, grey color of grey matter

dendrites

receive information from other neurons, dendritic spine, more dendrites = more input and more proteins

dendritic spine

receive input and transfer to cell body, little extensions off of the dendrite

arbors

pattern of dendrites

axon

singular process leaving the cell body

axon hillock

where the axon connects to the cell body

axon collaterals

the branches that come of the main branch of the axon

axon terminal

form synapses with target cells, contain synaptic vesicles, site of neurotransmitter release

synapse

made of presynaptic neuron + synaptic cleft + postsynaptic neuron

cytoskeleton

provides support and structure for neurons; microfilaments intermediate filaments and microtubules

intermediate filaments

provide tensile strength throughout the neuron, bundle to form neurofibrils, stains are specific because of different composition

anterograde transport

movement of material from cell body to the synaptic terminal

retrograde transport

movement of materials from the synaptic terminals to the cell body

unipolar neuron

bipolar neuron

multipolar neuron

astrocytes

most abundant glial cell, feet cover capillaries, control chemical environment around neurons

oligodendrocytes

type of glial cell, highly branched from a single soma, produce myelin sheath, can support axons of many surrounding neurons

microglia

type of glial cell, monitor neurons and extracellular space for health and signs of disrupted homeostasis, capable of phagocytosis

ependymal cells

line the CNS fluid-filled cavities, produce cerebrospinal fluid, cilia help circulate cerebrospinal fluid

satellite cell

surround ganglion neuron cell body, regulate cellular environment similar to astrocytes in the CNS

Schwann cell

myelinated PNS axons, critical for nerve regeneration

myelinated

few to many layers of lipid membrane wrapping

unsheathed

axons isolated from one another but no layers of lipids

nerve

cable-like bundle of parallel axons with their glia in the PNS

ganglion

cluster of neuron cell bodies in the peripheral nervous system

epineurium

surrounds the entire nerve

perineurium

surrounds a bundle of neurons

endoneurium

surrounds a single axon

Electrolytes

ions can carry electrical currents in solution

Ion channel

an integral membrane protein that allows ions to pass between intracellular and extracellular environments (leak and gated)

Selectivity

regulates the passage of ions based on size and charge

Receptor

an integral membrane protein that produces a physiological change in a cell after a ligand binds

Ligand

signaling molecule

Leakage ion channel

protein is always open, establish resting membrane potential, selective for a specific ion, net movement based on gradient

Passive movement

the movement of ions does not require ATP, they are following their gradient

Voltage Gated ion channel

gate opens in response to a change in membrane voltage (ex. Muscle and nerve cells)

Chemical (ligand) Gated ion channel

open in response to binding of an extracellular signal (ex. Neurotransmitters)

Ionotropic receptor

type of chemical receptor, channels that open or close in response to an extracellular signal; open ion channels allow ions to move and carry across the membrane

Metabotropic receptor

type of chemical receptor, proteins that respond to an extracellular signal by altering the metabolism in the cell

Neurotransmitter

ligands that are released from neurons at the synapse in order to communicate with different cells, can be excitatory or inhibitory

Acetylcholinesterase

enzyme that breaks down acetylcholine in the synapse

conformational change

single region changes shape on a gated channel protein

general structure change

entire pore changes shape on a gated channel protein

blocking gate

specialized protein responds and plugs the gate in a gated channel protein

4 rules of neurotransmitters

1) synthesized and released from a neuron
2) released from nerve terminals in an identifiable way
3) reproduce the events in another cell that occurred in the cell it was released from
4) must be a way to get rid of the chemical signal

acetylcholine

neurotransmitter that activates skeletal muscles

biogenic amines

ligands that affect mood, serotonin/dopamine/etc. removed from the synapse via uptake

GABA

inhibitory, principal inhibitory in the brain

Glycine

inhibitory, major inhibitory in the spinal cord and brain stem

glutamate

excitatory, principle excitatory in the brain

neuropeptide

small proteins made of the rough ER