- neurons have similar features to other body cells such as cell membrane, cytoplasm, mitochondria and nucleus
-neurons have special cell structures that enable them to transmit nerve impulses
-their four common features are dendrites, a cell body, an axon, and branching ends
-dendrites:
short branching terminals that receive nerve impulses from other neurons or sensory receptors
they relay the impulse to the cell body
-cell body:
contains the nucleus and is the site of the cell's metabolic reactions
processes input from the dendrites
if input is big enough, relayed to the axon, where impulse is initiated
-axon:
conducts impulses away from the cell body
range from 1mm to 1m, depending on location
terminal end branches into fibres
to communicate with adjacent neurons, glands, muscles, releases chemical signals into the space between
-myelin sheath:
fatty insulating layer enclosing axons and some neurons
white appearance
protects neurons and speed the rate of nerve impulsing
Schwann cells (glial cell) forms myelin by wrapping around axon
Classifying Neurons
Structure
a)
-single main dendrite
-single axom
-inner ear, retina, olfactory of brain
b)
-single proccess that extends from cell body
-dendrite and axon fused
-found in peripheral nervous system
c)
-several dendrites
-single axom
-brain and spinal cord
Function
1. Sensory input:
-Sensory receptors receive stimuli and form a nerve impulse
-Sensory neurons transmit impulses from sensory receptors to CNS
2. Integration:
-Interneurons found within CNS
-link between sensory and motor neurons
-process and integrate sensory info, relay motor info
3. Motor output:
-transmit info from CNS to effectors
- effectors: muscles, glands, organs
Reflex Arc
-simple connection of neurons that result in a reflex action in response to a stimulus
-sudden, involuntary responses to certain stimuli
e.g. blinking at incoming object, vomiting in response to irritating food
-involves 3 neurons to transmit messages, rapid, 50 milliseconds
-does NOT involve the brain
stimulus > pain receptor > sensory neuron > interneuron/spinal cord > motor neuron > effector (muscle) > response
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