B10 The Nervous System Flashcards
What is homeostatis
Homeostasis is the regulation of the internal conditions of a cell or organism to maintain optimum conditions for function, in response to internal and external changes.
Internal body conditions that are contolled
Temperature, blood glucose concentration, water levels
What are reflexes
Reflexes are rapid, automatic responses to certain stimuli that are unconscious as they dont involve the brain.
What is the reflex arc
Passage of imformation in a reflex
What is the reflex pathway
Stimuli receptor sensory neurone, relay neurone, motor neurone, effector, response
What is the brain?
The brain is an organ made up of billions of interconnected neurones in the central nervous system and is responsible for complex behaviours.
Function of Cerebral Cortex
Consciousness, intelligence, memory and language
Cerebellum function
Muscle coordination
Medulla
Unconscious activities - breathing and heart beat
How to study patients with brain damage? Neuroscientists
MRI scans (magnetic resonance imaging scanner) to see which brain parts are active when a human performs a task. Electrically stimulating the brain. Stimulates part of brain to see what effect it has on the body
What is the eye
The eye is a sense organ containing receptors sensitive to light intensity and colour.
Iris reflex in dim light
Radial muscle contracted and circular muscle relaxes. Pupils become wider. Pupil dilates
Iris reflex in bright light
Radial muscles relax and circular muscles contract. Pupil constricts
What is accomodation
This is when your lens chnges shape when you focus on near or distant objects
Eye accommodation focusing on a distant object
Ciliary muscles relax and suspensory ligaments pull tight. Lens becomes thin and refracts light rays slightly
Eye accommodation focusing on a nearby object.
Ciliary muscles contract and the suspensory ligaments slackens. Lens becomes thicker and refracts light rays strongly
What is myopia
Short sightedness. Can’t focus on distant objects as image is focused infront of retina.
What is Hyperopia
Long sightedness . Unable to focus on near objects because image is focused behind the retina
How to cure myopia
Concave lens which curves inwards so the light rays focus on the retina
How to cure hyperopia
Convex lens which curves outwards so the light rays focus on the retina.
Ways to improve eyesight
Spectacle lenses. Contact lenses, laser eye surgery, replacement lens
Cornea
Refracts light onto lens and is a transparent outer layer
Lens
Convex shape that refracts light onto the retina
Iris
Controls the size of the pupil. Coloured part and it is a muscle
