Nervous Tissue Flashcards
Neurology
The study of the nervous system.
Sensory Function
Detects external/internal stimuli.
Carries info to CNS
Integration function
Analyzes sensory info and makes decisions on how to respond.
Connects sensory neurons to motor neurons (CNS).
Motor function
Carries info from CNS to muscle contraction or gland secretion.
Neurons
Nerve cell
Produce nerve impulse (action potential).
Dendrite
Branches they receive info & carry nerve impulse to cell body.
Cell body
Main part of neuron, contains nucleus & organelles.
Axon
Usually single branch of neuron
Carries nerve impulse to next neuron, muscle, or gland.
Axon terminal
Contains neurotransmitters which cross synapse & send impulse to next neuron, muscle, or gland.
Myelin sheath
Covers axon
Composed of lipid & protein
Produced by Schwann cells (PNS) & oligodendrocytes (CNS)
Insulates axon &a increases speed of nerve impulse.
Nodes of Ranvier
Gaps between the myelin sheaths
Nerve impulse jumps from one node to the next.
Neuroglia (glia cells)
Make up about 1/2 of nervous system.
Function: support, nourish, & protect nerve cell.
Types of neuroglia in CNS
- Astrocytes
- Oligodendrocytes
- Microglia
- Ependymal cells
Types of neuroglia in PNS
- Schwann cells
2. Satellite cells
Astrocytes (CNS)
Support, maintain chemical balance around neuron, make “blood barrier,” & may be involved in learning and memory.
Oligodendrocytes (CNS)
Form myelin sheaths
Ependymal cells (CNS)
Produce, monitor, & aid in the circulation of cerebrospinal fluid.
Form blood-cerebrospinal fluid barrier
Microglia (CNS)
Phagocytize bacteria, dead cells, & damaged nerve cells.
“Clean up crew”
Schwann cells (PNS)
Form myelin sheaths for
Satellite cells (PNS)
Support neurons, regulate exchanges of material between neuron cell bodies & interstitial fluid
Unmyelinated axon
Continuous conduction
Impulse involves change occurring in axon membrane.
Grey matter
Myelinated axon
Saltatory conduction
Impulse only changes membrane at nodes (faster).
White matter
Multiple Sclerosis (MS)
Autoimmune disease that progressively destroys myelin sheaths.
Alternates between relapses & remissions.
Affects women more often than men.
Nerve
Bundle of axons, dendrites, or both in PNS.
Most found in CNS
Ganglion
Collection of cell bodies outside the CNS
Tract
Bundle of axons in CNS
Ascending - go up the spinal cord (sensory)
Descending - go down the spinal cord (motor)
Nucleus
Collection of cell bodies inside CNS
Central Nervous System (CNS) composed of…
Brain & spinal cord
CNS Function
Analyzes sensory info
Generates thoughts & emotions
Stores memories
Controls muscles & glands
Peripheral Nervous System (PNS) is composed of…
Nerves extending from brain & spinal cord (spinal nerves, cranial nerves, spinal plexus), ganglia, & sensory receptors
PNS Function
Sensory - collects impulses & carries them to CNS
Motor - carries response away from CNA to organs, muscles, or glands
Somatic nervous system (PNS)
Sensory neurons in skin, limbs, & sense organs (involuntary)
Motor neurons to skeletal muscles (voluntary)
Autonomic nervous system or ANS (PNS)
Involuntary
Includes sensory & motor neurons (cardiac &a smooth muscles) & glands.
Sympathetic division (fight or flight) Parasympathetic division (rest & digest)
Enteric nervous system (PNS)
Involuntary
Controls GI tract
Functions somewhat independently. Communicates with the CNS through sympathetic & parasympathetic neurons.
