Unit 1 Flashcards
Cells that make up nervous system?
Neurons and glia
Neurons
Send electrical signals to targets through body
Dendrites
Branched extensions that receive signals from other neurons. , main receptive or input regions., have receptor proteins
Axon
Typically transmits signals longer extension that
Transmits signals to other cells
Axon hillock
General area where action potentials the generated
Initial segment of axon
Usually the site where the “all or none”
Action potential is officially induced
Where are soma located?
Most located in CNS, protected by bones
Nissl bodies
Chromatophilic substances, where proteins manufactured, easily stained
Where are graded potentials formed?
Dendrites, formed here by specific stimuli, bringing positive charged ions like Na+
How does axon hillock work?
If enough positive charge enters via graded potential, triggers the action potential here, which moves down axon to targets
Axon terminals
Sites where axon connect to another cell
Synapse
Junction between branched ends of an axon and another cell, where there is a space/ cleft
Synaptic terminal
To continue signal transmission, specialized end of axon releases neurotransmitters using vesicle exocytosis
Post synaptic cell can be:
Neuron, muscle, gland
Glia
Support cells for neurons, greatly outnumber neurons
Ependymal cells
Line the central cavities throughout brain and spinal card
Ciliated ependymal
Circulate cere’brospinal fluid, plays role in immunity, protection, cushioning, nourishment of CNS
Oligodendrocytes
Produce myelin sheaths in tracts in the CNS, to speed up signal transmission
- single oligodendrocyle can bundle multiple axons
Formation of myelin sheath in PNS
Formed by Schwann cells along motor neurons, functionally similar to oligodendrocyles in CNS
Schwann cells typically wrap around a
Single axon at a time
Function of myelin sheath
Increase speed of signaling, insulate axons and makes “gaps” called mode of ranvier between the glia
Purpose of node of rangier
Decrease amount of membrane that needs to depolarize during an action potential
- electrical signal jumps from gap to gap “saltatory conduction” speeds up signaling
Satellite cells
Support cell bodies in PNS, linking neurons to capillaries for nutrients
- provide buffer zone between circulatory system and PNS
Location of satellite cells
Unipolar neuron and ganglia of PNS