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B10: The Human Nervous System - Coggle Diagram
B10: The Human Nervous System
10.1 Principles of Homeostasis
Homeostasis - The regulation of the internal conditions of a cell or organism to maintain optimum conditions for function
3 main uses are:
Blood glucose levels
Water levels
Core body temperature
Receptors - Detect change in environment (stimuli)
Coordination Centres - Receives and processes the information from receptors
Effectors - Muscles or glands that bring about responses to the stimulus received
10.6 Common Problems of the Eye
Accommodation - The process of changing the lens to focus on near or distant objects
To focus on close, ciliary muscles contract, the suspensory ligaments loosen, the lens becomes thicker so it can refract light strongly
To focus on distant, ciliary muscles relax, suspensory ligaments are pulled tight, the lens becomes thin so it only refracts the light rays slightly
Myopia - short sighted (treated with concave glasses/contact lenses, laser eye surgery, replacement lens)
Hyperopia - long sighted (treated with convex glasses/contact lenses, replacement lens)
10.3 Reflex Actions
Automatic and rapid and do not involve the conscious parts of the brain
Reflexes involve sensory, relay, and motor neurones
Contro everyday functions like breathing and digestion and help you avoid danger
Stages of a reflex arc are: stimulus > receptor > sensory neurone > relay neurone > motor neurone > effector > response
10.2 Structure & Function of Nervous System
Uses electrical impulses to enable you to react quickly to your surroundings
Impulses pass from the receptors, pass along sensory neurons to the brain or spinal cord, brain coordinates response and sends it back along the motor neurone from the brain to the effector
10.4 The Brain
Cerebral Cortex - Consciousness, intelligence, memory, balance
Cerebellum - Coordinating muscular activity and balance
Medulla - Unconscious activities such as heartbeat, breathing, gut movement
Brain is made up of billions of interconnected neurons that control complex behaviour
Map regions of brain by studying patients with brain damage (e.g. Phineas Gage), electrically stimulating different areas, and by using MRI
10.5 The Eye
Eye is a sense organ, contsind receptors in the retina that are sensitive to light and colour
The tough sclera (white bit) has a clear front part called the cornea which lets light in and refracts light towards the retina
Muscular iris controls size of the pupil & amount of light entering the eye
Ciliary muscles and suspensory ligaments change the shape of the lens to fine focus light onto the retina
Optic nerve carries impulses from retina to the brain