B3.1 - The Nervous System Flashcards
What is a stimulus?
A change in the environment detected by the body
What is a receptor?
A group of cells/organ that detects a stimulus
What is a sensory neurone?
A nerve cell that carries an impulse to your brain to understand the stimuli detected by the receptors
What is a motor neurone?
A nerve cell that sends impulses from the central nervous system to effectors to cause a response
What is the Central Nervous System?
The cooperation between the brain and spinal cord to help us detect and react to external stimuli
What is the Periphery Nervous System?
The network of nerves that runs throughout your body carrying impulses
What is the pathway of the impulse from receptor to effector?
Stimulus
Receptor
Sensory neurone
Central nervous system
Motor neurone
Effector
Response
What is the overall function of the nervous system?
To send messages from the body to the brain, and from the brain to the body to give a response to that stimulus, regulating thoughts and movements
What are some examples of stimuli?
Change in temperature
Taste
Pain
What is the function of the relay neurone?
Carries electrical impulses from sensory neurones to motor neurones
What is the cornea and its function?
Transparent coating on the front of the eye
Protects the eye
Refracts light entering the eye
What is the iris and its function?
Coloured ring of muscle tissue surrounding the pupil
Alters pupil size by contracting or relaxing
What is the pupil and its function?
Central hole in the iris
Allows light to enter the eye
What is the lens and its function?
Transparent biconvex lens
Focuses light clearly onto the retina
What are the ciliary muscles?
Rings of muscle tissue
Alters the shape of the lens
What are the suspensory ligaments and their function?
Ligament tissues that connect ciliary muscles to the lens
What is the retina and its function?
Nervous tissue that detects light and sends nerve impulses to the brain
What happens when the eye focuses on near objects?
Ciliary muscles contract
Suspensory ligaments relax and loosen
The lens thickens and increases curvature to allow light to refract stronger
What happens when the eye focuses on distant objects?
Ciliary muscles relax
Suspensory ligaments contract and tighten
The lens becomes thinner and flatter to allow light to refract more weakly
In normal vision, where is the image formed?
The fovea
In normal vision, why is the image formed at the fovea?
Light refracts through the lens due to its curved biconvex structure
What is myopia?
Also known as near-sightedness, where light from distant objects focuses in front of the retina
Distant objects appear blurry while close objects appear normal
In myopia, where is the image formed?
Before light reaches the fovea
What causes myopia?
The shape of the lens is too strong and too curved, so there is too much refraction
What can be done to correct myopia?
It can be managed with a concave lens to reduce refraction of light
What is hyperopia?
Also known as long-sightedness, where light from close objects focuses behind the retina
Close objects appear blurry while distant objects appear normal
In hyperopia, where is the image formed?
After light reaches the fovea
What can be done to correct hyperopia?
A more convex lens to refract light more strongly
