The Nervous System Flashcards
Parts of neuron (5)
Cell body Dendrites Axon Axon endings Myelin sheath
Neuron categories (3)
Afferent (sensory)
Efferent (motor)
Interneurons
Dendrite
Branching projections, receive signals from other neurons
Axon
Long extension conducts impulse away from cell body
Axon terminals
Release neurotransmitters which affect other neurons or effectors (muscles/glands)
Myelin sheath
Insulating outer layer of axon which increases rate of conduction of a nerve impulse and helps to repair. Made of Schwann cells.
Node of Ranier
Sections of axon exposed (uncovered by myelin sheath) which nerve impulses jump to.
Afferent neurons
Sensory
Send Info toward brain & spinal cord from sensory receptors
Efferent neurons
Motor
Send Info away from brain & spinal cord to muscle or gland
Interneurons
Integrate and interpret sensory signals
Send between neurons
Action potential
Nerve impulse
From resting potential (charge at rest):
1. Depolarization (reversal of charge across membrane)
Excitatory stimulus opens Na+ gates
Na+ ions enter neuron, increasing positive charge
If threshold is reached, more Na+ channels open
Net positive charge
- Repolarization (restoration of charge across membrane)
During action potential, K+ channels open
K+ ions leave cell
Interior negative charge restored
Nerve
Bundle of parallel axons, dendrites or both, covered with connective tissue.
Can be afferent, efferent, or both.
Neurotransmitter
A chemical released at the axon terminal of the presynaptic neuron after an action potential which diffuses across the synaptic cleft and acts on the post synaptic neuron.
Synapse
Junction between a neuron and another cell
Meninges
3 protective tissue coverings of brain and spinal cord
Meningitis is infection of these tissues
Parts of the central nervous system (7)
Cerebrum Cerebellum Thalamus Hypothalamus Brain stem Hippocampus Limbic system
Cerebellum
Coordinates sensory-motor voluntary movement
Memory of learned motor patterns
Brainstem
Autonomic centers (heart rate, digestion)
Relays sensory info to thalamus
Integrates sensory input
Cerebrum
Houses sensory areas
Motor areas, voluntary movement
Language, memory, decision making
Corpus callosum
Allows communication between left and right brain
Thalamus
Processes sensory information and relays to higher brain
Hypothalamus
Controls homeostatic functions
Emotional center
Circadian rhythms
Limbic system
Group of structure which produce emotions and memories
Cerebrum Thalamus Hypothalamus Hippocampus Amygdala Olfactory bulb
Hippocampus
Long term memory
Peripheral nervous system (function and organization)
Carry info between CNS and rest of body
Somatic nervous system
-carries sensory info
-controls voluntary movement
Autonomic nervous system
-maintains homeostasis
-controls involuntary movement
Sympathetic
-fight or flight
Parasympathetic
-rest and digest
Types of sensory receptors (5)
Mechano Thermo Photo Chemo Pain
Sclera
White of eyeball
Protects, shapes, attaches to muscle
Cornea
Provides window for light
Choroid
Layer heavy with blood vessels to supply nutrients and oxygen
Lens
Focuses light on the retina
Iris
Colored part of eye regulates amount of light entering
Pupil
Opening for light to enter eye
Retina
Contains photoreceptors (rods and cones)
Fovea
Section of retina which contains highest concentration of photoreceptors
Vitreous humor
Fluid filling posterior chamber of eye maintaining shape. Is never replenished.
Aqueous humor
Fluid filling anterior chamber of eye. Supplies nutrients and oxygen to lens and cornea and carries waste. Continuously produced.
Gray matter
Cell bodies in thin outer layer of each hemisphere (cerebral cortex)
