Nervous system Flashcards
What is homeostasis
The regulation of the conditions inside your body to maintain a stable internal environment, in response to changes in both internal and external conditions.
What is negative feedback
The mechanism that restores the optimum level.
What is a stimulus
A change in the environment that you might need to respond to.
Give 3 examples of a stimulus
- Light
- Sound
- Touch
- Pressure
- Pain
- Change in position or temperature
What is an coordination center
It receives and processes information about an stimulus and organises a response
What is a nervous system
Your nervous system is what allows you to react to your surroundings. It also allows you to coordinate your behavior.
What are receptors
Cells that detect stimuli
What is the central nervous system
Where all the information from the receptors is sent, and where reflexes and actions are coordinated.
What do neurons do
They transmit information as electrical impulses to and from the Central nervous system
What are effectors
Muscles and glands which respond to nervous impulses and bring about a response to the stimulus
How do muscles respond to nervous impulses
They contract
How do glands respond to nervous impulses
They secrete chemical substances called hormones
What are sensory neurones
The neurones that carry information as electrical impulses from the receptors in the sense organs to the central nervous system
What are relay neurones
The neurones that carry electrical impulses from sensory neurones to motor neurones. They are found in the central nervous system.
What are motor neurones
The neurones that carry electrical impulses from the central nervous system to the effectors
What is a synapse
The connection between two neurones
How are nerve signals transferred across the synapse
The nerve signal is transferred by chemicals which diffuse across the gap.
What is a reflex
a fast, automatic response to a stimulus
What is reaction time
The time it takes to respond to a stimulus
How can reaction time be affected
Age
Gender
Drugs
where is the cerebral cortex located
The outer wrinkly layer of the brain
What is the cerebral cortex responsible for
Consciousness, intelligence, memory and language
where is the medulla located
At the base of the brain, at the top of the spinal chord
What is the medulla responsible for
It controls unconscious activity (Things you don’t have to think about doing) Like breathing and heartbeat
Where is the cerebellum located
At the back of the brain
What is the cerebellum responsible for
Muscle coordination
What is the sclera
The tough, supporting wall of the eye
What is the cornea
The transparent outer layer at the front of the eye. It refracts light into the eye.
What is the pupil
the hole in the center of the eye, where light enters
What is the iris
contains muscles that allow it to control the diameter of the pupil and therefore how much light enters the eye
What is the Retina
the layer at the back of the eye that contains two types of light receptor cells
What is the lens
focuses light on the retina
What do ciliary muscles and suspensory ligaments do
control the shape of the lens
What is the optic nerve
carries impulses from the receptors on the retina to the brain
What does the eye do to focus on near objects
- The ciliary muscles contract, which slackens the suspensory ligaments.
- The lens becomes more curved
- This increases the amount by which it refracts light
What does the eye do to focus on distant objects
- The ciliary muscles relax, which allows the sensory muscles to contract.
- This makes the lens go thin
- So it refracts light by a smaller amount
