The Nervous System Flashcards
What is stimulus?
This is the change in the environment that an organism responds or reacts to.
What are 5 examples of a stimulus?
Light
Temperature
Texture
Chemical in air
moisture
What is a response?
This is the change in the organism because of the stimuli.
Why is response to stimuli important to an organism?
It is important for the organism’s survival
What are receptors?
This is a part of an organism that detects the stimulus.
What are effectors?
This is a part of an organism that responds to the stimulus.
Give five examples of receptors
These are sense organs :
Eyes
Ears
Nose
Tongue
Skin
Give two examples of effectors
Muscles and glands
How does the eye respond to stimulus?
At the back of the eye is the retina which is a layer of sensory cells (rod and cone cells) that responds to light. Impulses are sent from these cells to the brain through the optic nerve so that changes in shape, color, brightness and distance are detected.
How does the ear respond to stimulus?
Sensitive hairs in the inner ear respond to vibrations in the air( sound waves) . Impulses are sent from these hairs to the brain by the auditory nerve so that changes in the tone, pitch, quality and loudness can be detected.
How does the nose respond to stimulus?
As air flows in the nose during breathing, chemical molecules in it touch sensitive hairs. These send messages to the brain to detect changes in scent.
How does the tongue respond to stimulus?
Groups of receptor cells called taste buds, responds to chemicals in the food. Different parts of the tongue are sensitive to different flavors like salt, sugar, bitter, sour. These send messages to the brain to detect the changes in flavor of the food.
How does the skin respond to stimulus?
The skin is the largest organ in the body.
Nerves ending as sensory cells are scattered throughout the skin. These are sensitive to pain , touch, change in temperature, light pressure and heavy pressure. They send impulses to the brain to detect what has been touched.
What does the nervous system do?Give examples
It controls the body.
Example: thinking, reactions and movement
What is the nervous system made up of?
It is made up of neurones or nerve cells
What is the purpose of neurones?
They transmit electrical impulses to and from the brain
What makes up a nerve?
Many neurones help together by a sheath
What is the nervous system made up of? And give what they consist of
CNS- central nervous system
Brain and spinal cord
PNS- peripheral nervous system
Made up of all nerves outside of the brain (cranial nerves) and all the nerves outside the spinal cord ( spinal nerves)
Is the PNS under conscious control? And state what 3 things it controls
No
It controls the
1.breathing rate
2.Digestion
3.Heart rate
What are the 3 types of neurones and state what they do.
- Sensory neurones - conducts electrical impulses from receptors to the CNS
- Motor neurones - conducts electrical impulses from the CNS to the effectors
- Intermediate or relay neurones - links sensory neurones to motor neurones. They are found in the CNS.
What does the dendrite and dendron do?
They carry impulses to the cell body.
What does axons do?
They carry impulses away from the cell body and to a next neurone.
What does the myelin sheath do?
This surrounds the axon and dendron. It insulates that part of the neurone so electrical impulses can be transmitted faster.
Describe the node of ranvier and what they do?
This is a gap between the myelin sheath. They speed up the impulses.
