Slide A Flashcards
Nervous system
Central nervous system
Peripheral nervous system
Central nervous system
Brain
Spinal cord
Peripheral nervous system
Cranial nerves (12)
Spinal nerves (31)
Neurons
Specialized cells that carry “messages” through an electrochemical process
Human brain has about
100 billion neurons
Dendrites
Bring information to the cell body
Rough surface (dendritic spines)
Usually many dendrites per cell
Have ribosomes
No myelin insulation
Branch near the cell body
Axons
Take information away from the cell body
Smooth surface
Generally only 1 axon per cell
No ribosomes
Can have myelin
Branch further from the cell body
Irritability
Ability to respond to stimuli
Conductivity
Ability to transmit an impulse
Neuroglial cells
Provide support and nutrition
Maintain homeostasis
Form myelin
Signal transmission
Support and protection for neurons
Surrounds neurons and holds them in place
Supply nutrients and oxygen to neurons
Insulate neuron
Destroy pathogens and remove dead neurons
Schwaan cells
Successive wrapping off the cell membrane form the insulating myelin
Outer surface encased in glycoprotein basement membrane which forms sheath of schwaan
Nodes of ranvier
Unmyelinated areas between adjacent schwaan cells
Nerve impulses are generated at these areas
Satellite cells
Support neuron cell bodies within ganglia
Oligodendrocytes
Provide the insulation(myelin) to neurons in the central nervous system
Each has extensions that form insulating myelin sheaths around several axon
Microglia
Phagocytes, migratory
Ependymal cells
Line ventricles and secrete CSF
Astrocytes
Most abundant glial cells
Star shaped cells that provide physical and nutritional support for neurons
Clean up brain debris
Transport nutrients to neurons
Holds neurons in place
Digest parts of dead neurons
Regulate content of extracellular space
Blood brain barrier
Joined by tight junctions
Diffusion active transport endocytosis
Exocytosis
How neurons work
Reception
Transmission
Data interpretation
Transmission
Response
Reception
Receptors in the skin sense stimuli
Transmission
Sensory neurons transmit the touch message
Data interpretation
Information is sorted and interpreted
Transmission 2
Motor neurons transmit a response message to a muscle
Response
Muscles are activated causing a response
Impulse transmission
Start with a resting neuron
Plasma membrane controls [ ] of ions inside the cell
Na+ and K+ on both sides of membrane
Na+ higher conc outside
K+ higher conc inside
How an impulse travels
Stimulus excites neuron
Na channels open Na build up inside
Inside more + than outside
Change in charge (depolarization)
Membrane immediately behind depolarization returns to resting state
Resting state-inside negative, outside positive
Resting state
A neuron is not conducting an impulse
The K+ concentration is much higher inside than out
Na+ concentration is much higher outside the cell than in
Depolarization
A nerve cell is stimulated
Membrane becomes permeable to Na for an instant and they quickly move into the cell
Inner surface of the cell membrane is now more positively charged then the outside
Repolarization
When the membrane becomes depolarized K+ automatically leaves the cell until the cell is back to its resting state
