Nervous system Flashcards
(10 cards)
components (NS)
Brain, spinal cord ,peripheral nerves, sensory nerves.
function
-Directs immediate responses to stimuli.
-Coordinates or moderates activities of other organ systems.
-Provides and interprets sensory information.
Central Nervous system(CNS)
Neuroglia
1-Astrocytes
2-Microglia
3-Ependymal cells
4-Oligodendrocytes
5-Schwann cells & satellite cells.
Central Nervous system(CNS)
NEURONS-
1- capable of measuring the environment
2-making decisions
3-sending orders
major portions of the brain
1-cerebrum
2-cerebellum
3-brain stem
Action potential velocity-electrical impulse
myelinated fibers-
1-saltatory conduction- potential travels quickly from one break in myelin to the next.
2-action potential is slower in unmyelinated fibers than in myelinated fibers.
Diameter of a neuron
1-larger diameter neurons conduct nerve impulses faster.
2-larger diameter neurons present less resistance to current flow.
Electrical impulse
1-Depolarization- inside of cell becomes less negative relative to outside (>-70mV)
2-Hyperpolarization-inside of cell becomes more negative to outside (<-70mV)
3-Graded potentials-localized changes in membrane potential (either depolarization or hyperpolarization.
4-Action potentials-rapid, substantial depolarization of the membrane (-70mV to +30mV to -70mV all in 1ms)
The protective Mechanisms-muscle spindles
-lie between and are connected to regular skeletal muscle fibers.
-The middle of the spindle cannot contract but can stretch.
-when muscles attached to the spindle are stretched, neurons on the spindle transmit information to the CNS about the muscles length.
-reflexive muscle contraction is triggered to resist further stretching.
Golgi Tendon organs
-Encapsulated sensory organs through which muscle tendon fibers pass.
-located close to the tendon’s attachment to the muscle.
-sense small changes in tension
-inhibit contracting (agonist) muscles and excite antagonist muscles to prevent injury
