B3.1 The Nervous System Flashcards
What is the difference between the central nervous system and the peripheral nervous system?
The central nervous system is the brain and the spinal cord, the peripheral nervous system is every other part of the nervous system
What is a stimulus?
A stimulus is a change in the environment
What type of neurone connects a receptor to the CNS?
A sensory neurone
What is an effector?
A part of a body that brings about the response to a stimulus like a muscle or a gland
What type of neurone connects the CNS to an effector?
A motor neurone
Describe the reflex arc
Stimulus detected by a receptor
Impulse passed along sensory neurone to CNS Impulse passed along motor neurone to effector
Effector brings about the response
What is the cornea and what is its function?
The transparent layer in front of the eye that protects the eye from damage
What is the iris and what is its function?
The coloured ring around the pupil that controls its diameter
What is the pupil and what is its function?
The pupil is the hole in the middle of the iris that lets light into the eye
What is the optic nerve and what is its function?
The nerve coming out the back of the eye that sends signals to the brain
What is the function of the lens?
The lens focuses the light rays onto the retina
What is the retina and what is its function?
The retina is the back part of the eye and it converts visual stimuli into electrical impulses
What do the ciliary body and suspensory ligaments do?
They control the shape of the lens (accomodation)
What defect in the eye causes short sightedness?
The lens focuses light rays in front of the retina so far away objects appear blurry
How is short sightedness corrected?
By wearing glasses that have concave lenses
What defect in the eye causes long sightedness?
The lens focuses light behind the retina so nearby objects appear blurry
How is long sightedness corrected?
By wearing glasses that have convex lenses
What is colour blindness?
- It is an inherited condition where people find it difficult to tell the difference between colours
- It is caused by a defect in the retina and there is currently no cure
Where is the cerebrum located and what is its function?
- It is located at the front of the brain
- It controls conscious functions, memory and language
Where is the cerebellum located and what is its function?
- It is located at the back bottom of the brain
- It controls muscular movement and balance
Where is the medulla located and what is its function?
- It is located in the brainstem in the middle at the bottom
- It controls unconscious functions like heart rate and breathing
What is the function of the hypothalamus?
- It acts as the regulatory centre and controls things like body temperature, water content and salt balance
What is the function of the pituitary gland?
- It releases hormones into the blood
Give 2 reasons why it is difficult to investigate brain function (Higher)
- Surgery is not risk free
- People with brain disorders may be unable to consent
Why is it difficult to treat brain disorders? (Higher)
- The brain and spinal cord are very difficult to access
- Tissues in the CNS cannot regenerate
- Drugs cannot penetrate the blood-brain barrier
