Lecture 11.1-11.5 Flashcards
Nervous system
master controlling and communicating system of the body
Basic functions of the NS
(3)
- sensory input
- integration
- motor output
one NS, divided into two parts. called
Central nervous system (CNS)
Peripheral nervous system (PNS)
afferent vs efferent
afferent is sensory, impulses sent TO CNS
efferent is the response, impulse leaves CNS
NS is made of two type cells
- neuroglia
- neurons
neuralgia
supporting cells, smaller and wrap around delicate neurons
neurons
excitable nerve cells
astrocytes
- most abundant
- cling to neurons and cover nearby capillaries
- control chemical environment around neurons
Microglial cells
- ouch nearby neurons and monitor their health
- phagocytizes
Ependymal cells
Form barrier between CSF that fills the cavities and the tissue fluid covering the cells of CNS.
Oligodendrocytes
producing an insulating cover called myelin sheath
Satellite cells
Same functions as astrocytes
Schwann cells
similar to oligodendrocytes
Neurons are..
structural units of the NS
neuron structural components
- cell body
- axon
- dendrites
- axon terminals
- myelin sheath
- nodes of raniver
- nucleus
nucleus vs gangion
Clusters of cell body in CNS = nuclei
clusters of cell body that lie along PNS = ganglia
nerve vs tract
Bundles of axons =
tracts (CNS)
nerves (PNS)
importance of myelin sheath
Protects and electrically insulates fibers, and increases transmission speed
Myelination in PNS
schwann cells (SC)
Wrapping is loose at first but SC cytoplasm is gradually squeezed
Outer collar of perinuclear cytoplasm
Myelination in CNS
Has both myelinated and unmyelinated axons
Lack outer collar of perinuclear cytoplasm because the squeezed out cytoplasm is forced back to the nucleus
Outer collar of perinuclear cytoplasm
nucleus and cytoplasm of SC end up as a bulge external to MS
Voltage
measure of potential energy
Current
flow of electrical charge from one point to another
Resistance
hindrance to charge flow
Ohm’s law
gives relationship between voltage, current and resistance where
current = V/R
Chemically gated channels (ligand gated)
open when the right chemical (neurotransmitter) tries to bind
Voltage gated channels
open and close to change in membrane potential
Mechanically gated channels
open when to physical deformation of receptor
Electrochemical gradient
determines the way ions move
2 parts Electrochemical gradient:
Concentration gradient: ions move along CG from low to high
Electrical gradient: ions move to opposite charge
Change in potential can produce 2 types of signals
Graded potential: incoming signals operating over short distances
Action potential: long distance signals of axons that always have same strength
Graded potentials (GP)
short, localized changes in MP, usually in dendrites or cell body
GPs are triggered by change, and are given different names 2
Receptor/generator potential: produced when sensory receptor is excited
Postsynaptic potential: when the stimulus is a neurotransmitter released by another neuron.
Graded potentials (GP) example
Pacemaker cells in the heart generate graded potentials that initiate the heartbeat.
