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The nervous system - Coggle Diagram
The nervous system
Homeostasis
homeostasis is the maintain a constant internal environment due to change in the external environment
- the spinal cord and the brain make up the nervous system
- reflex actions are important as they keep you from harm
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KEY WORDS:
:no_entry:stimulus:no_entry: change to the environment
:no_entry:receptor:no_entry: detects stimulus
:no_entry:CNS:no_entry: centreral nervous system- process info and sends message to counteract change (made up sensory neurone [ relay neurone] and motor neurone
:no_entry:effector:no_entry: muscle/ gland which brings about change
:no_entry:response:no_entry: what is sone to counteract change
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The Brain
the brain controls complex behaviour it is made of interconnected neurons and has different regions that carry out different functions
- cerebral cortex (cerebrum) - made up of 2 hemispheres and controls memory, consciousness, language and intelligence
- cerebellum - coordinates muscular activity and balance
- medulla - controls unconscious activity such as breathing and heart rate
Why is the brain so hard to treat ?
the brain is hard to treat because it is so delicate and very complex but neuroscientists in the recent years have founds ways to investigate the brain for example using MRI scans or electrical stimulating the brain
The eye
- cornea = refracts light as it enters the eye
- iris = comtrols how much light enters the eye
- lens = further refracts light to focus onto retina
- retina= contains light receptors
- optic nerve = carries impulse from the eye to the brain
- sclera = tough white outer layer of the eye to help protect injury
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Bright light - circular muscles contract// radial muscles relax// pupil constricts
Dim Light - circular muscles relax // radial muscles contract // pupil dilates
Problems with the eye
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focus on near objects: ciliary muscles contract // suspesnsory ligaments loose // lens fat and thick focus on far objects: ciliary muscles relax // suspesory ligaments taut // lens thin and flat
EYE DEFECTS
myopia (short sightedness) - eye may be elongated and when light enters the eye it refracts too much causing difficulty to view distant objects but maybe not near objects
hyperopia (long sightedness) - eye may be too short and when light enters the eye it focuses behind the retina causing difficulty not seeing close objects
to correct MYOPIA= use concave lens // to correct HYPEROPIA = use convex lens other treatements:
- laser eye surgery - corrects shape of cornea
- contact lenses - acts the same way glasses do