TEST 3 Neurons Flashcards
Function of Nervous System (3)
1) Receive and collect Information(Dendrites) 2)process received information (soma/body) 3) Respond to information (axon)
Structure of the Nervous System 2
1) CNS Central nervous system (Only Brain/Spinal Cord) 2) PNS Peripheral Nervous system (other nervous tissue; cranial and spinal nerves
Two Functions of Nervous system
1) Sensory (afferent) 2) Motor Efferent)
Sensory (afferent) Function
Toward CNC from periphery
Motor (efferent)
Toward periphery from CNS 1) Somatic (to skeletal muscle 2) Autonomic ( anywhere else : smooth/cardiac muscle and glands
Neuron chars
Respond to stimuli and send nerve impulses (action potential)
Different Parts of Neuron
1) Soma 2) Dendrites 3) Axon 4) Axon Hillock (begin AP) 5) Axon collaterals(branches) 6) Axon terminals(telodendria) 7) Synaptic Knobs 8) Synaptic vesicles 9) Myelin sheath 10 Nodes of Ranvier
Axon Hillock
Triangular region connecting axon to cell body where the AP(action potential) Begins
Axon collaterals
Side branches of an axon
Axon terminals (telodendria)
Fine terminal branches of an axon or axon collateral
Synaptic knobs
Slightly expanded regions at the tips of Axon terminals (telodendria)
Synaptic vesicles
Contain Neurotransmitters (i.e.. acetylcholine (ACh)
myelin sheath
White covering that speed up an action potential
Nodes of Ranvier
Gap/spaces between myelin sheath( sausages)
What are supporting cells Called in the nervous system
Glial Cells
Characteristics of Glial cells(6)
1) Supporting cells 2) No AP 3) Can divide 4) Outnumber neutrons 5) smaller then neurons 6) 6 main types
6 types of Glial Cells and Location
1) Astrocytes (CNS) 2) Ependymal Cells (CNS) 3) Microglia (CNS) 4) Oligodendrocytes 5) Satellite Cell (PNS) 6) Schwann cells (PNS)
Astrocytes Char
BLOOD BRAIN barrier 2) Most Common 3) Star shaped 4) Provide structural support
Ependymal Cells
1)PRODUCE CEREBROSPINAL Fluid (CSF) 2) Cilia to circulate fluid 3) Form choroid plexus(network) 4) Line Ventricle of BRAIN and CENTRAL canal of spinal canal (CNS)
Microglia Char
1) Phagocytize dead/damaged nervous tissue 2) <5% of neuroglia
Oligodendrocytes
1) COVER AXON forming MYELIN Sheath (IN CNS) 2) Large 3) Cytoplasmic processes
Satellite Cells
1) Regulate exchange of nutrients / waste products 2)separate cell soma of neutron interstitial fluid
Schwann Cells(neurolemmocytes)
Form Myelin sheath in the (PNS)
Myelin Sheath CNN vs PNS
Oligodendrocytes (multi) in CNS and Schwann cells (portion of an axon) in PNS
Whats a Neurons neutral state?
Starts at a resting membrane potential (-70mv) (more negative on the INSIDE)
How does a membrane maintain is membrane potential(-70mv)
1) Ion concentration (K+ Phosphate -; - protein all inside and NA+ Cl- outside) 2) Relative permeability of cell membrane to ions (m more permeable to K+ than anything else) 3) Na+/K+ pumps (2K+ IN & 3 NA+ out
Action Potentials
1) Neuron send electrical impulses call action potentials (AP) 2) AP occurs when a stimulus CAUSES the NEURON to DEPOLARIZE. 3) If the neuron I depolarized to a CRITCAL Threshold (55mv) an Ap is generated(wave of depolarization)
Depolarization is due to
NA+ ions rush IN inward(voltage -gate NA+ channel open)
Repolarization Follows due to
K+ Flowing out (Voltage - gate K+ Channels Open
Refractory Period and Types
Period after AP when it is difficult or impossible to generate other AP 1)Absolute (no AP can be generated regardless of stimulus 2) Relative: An AP can be generates but requires a larger then normal stimulus
Myelinated AP Conduction
Ion flow can only at nodes of Ranvier; Saltatory Conduction( Skips sections Pass electrical current Faster)
Unmyelinated AP conduction
No Node has continuous conduction (slower)
All or None Law
If an AP is generated it will trail the ENTIRE length of the axon without losing strength(like shooting a gun)
What happen in Axon Terminals
When AP reaches end of axon; cause voltage gated Ca+ channels to open and then neurotransmitter(chemical) is released. The Neurotransmitter cross synapse (synaptic cleft and bind receptor on another cell ( muscle gland or another neuron) causing a response.
What are the TWO main neurotransmitters
1) Norepinephrine(NE) and Acetylcholine (ACh)
Presynaptic neuron vs. post-synaptic neuron
Presynaptic neuron is the one simulating or inhibiting the other neuron while the Postsynaptic is getting acted on.
Stimulus to the Post-synaptic neuron 2 TYPES
Excitatory postsynaptic potential(EPSP) - depolarize the postsynaptic neuron 2) Inhibitory postsynaptic potential (IPSP) Hyperpolarize the postsynaptic neuron
Nerve fiber
Axon
Nerve
Bundle of axons in Peripheral NS
Ganglion
Cluster of neuron cell bodies in PNS
Nucleus
Cluster of cell bodies in CNS
Tract
Bundle of axons in Central NS
Endoneurium
Cover individual axons
Perineurium
Cover fascicles of axons
Epineurium
Covers entire nerve
White VS Gray Matter in CNS
White : mylinated axons Gray: no myelin(somas dendrites; unmylelinated axons; neuroglia) IN SC the white surrounds the gray while in the brain gray surrounds white with grey in the middle
Multipolar Neurons(2)
1) 1 axon; several dendrites 2)Motor neurons; interneurons
Bipolar Neurons (2)
1) 1 axon & 1 main dendrite 2) RARE (retina of eye; olfactory neurons)
Unipolar Neurons (5)
1) 1 process divides into 2 branches 2) Branches resemble axons 3) Dendrites at tip of axon 5) Sensory neurons
