2. RECEPTORS IN DIFFERENT
BODY ORGANS
ORGAN/SENSE
Photoreceptors temperature
Mechanoreceptors pain
Chemoreceptors nose
Olfactory receptors ears
Nociceptors eyes
Thermoreceptors tongue
MATCH COLUMN A WITH COLUMN B
6. THE NEURONS
The basic unit of the nervous system is the neuron or
nerve cell which carries impulses to the nervous system. A
neuron is composed of the following parts:
dendrites, nucleus, cell body, axon, nodes of
Ranvier, myelin sheath cells and the axon terminal.
7. A neuron is composed of the cell body which contains
the nucleus and is covered by myelin sheath with an axon
terminal at its end.
The dendrites receive the impulses and carry these
toward the cell body while the axon carries the impulses
away from the cell body which passes along the different
parts of the neuron .
Axons then pass the impulses to the dendrites of the other
neurons’ cell body in the muscle cells. At the end of these
dendrites, signals originate as a dendrite is called the
receptor site of neurons
8. Classification of Neurons
1. Sensory or affective neurons carry
impulses from the sense organs to the brain
and spinal cord.
2. Motor or effective neurons carry impulses
from the brain and spinal cord to the muscles.
3. Associative neurons, located in the CNS,
analyze and interpret the data or impulses.
9.
10. The nervous system is assisted by five sense organs
- the eyes, ears, nose, tongue, and skin. These sense
organs are constantly receiving information from the
environment and sending messages to the brain. These
senses aid in the survival of human beings. A stimulus
(plural: stimuli) is any factor in the environment that may
trigger a nerve impulse. A response is a reaction to a
stimulus. A stimulus is received by the body and a
response is made. An organism must be able to respond
to a stimulus in order to survive.
11. How is a message transported?
1. The five sense organs namely, the eyes, ears, nose,
tongue and skin collect the information and send it to the
brain in a nerve impulse.
A nerve impulse is a wave of a chemical reaction and
electrochemical change.
2. When a nerve impulse reaches the axon terminal,
neurotransmitters are released which send the information
across the synapse to stimulate the next neuron. The
information transmitted is called action potential
12. Reaction time happens in the length of time between the
activation of the stimulus up to its recognition.
