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Coordination and control – The nervous system
Coordination and control – The nervous system
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The structure and function of the nervous system
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Reflex arc
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Practical activity
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The brain
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Investigating brain function
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Treating severe head injuries
- The eye
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How the eye works – Higher
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Common defects of the eye and how they can be overcome
HOMEOSTASIS – The process of maintaining the constant internal environment
Nervous System and the Hormonal System
Homeostasis is important for the enzymes as the enzymes control all the reactions of the body and they need optimum condition to work.
NEURONES
Motor Neurone- Motor Neurones connect the CNS to the Effectors
- Takes impulses away from CNS
- Motor neurones sends the message from the central nervous system to the effectors.
Sensory Neurone
- Sensory Neurones connect sense organs with the Central Nervous System.
Relay Neurone
- Relay Neurones are present in the CNS and occur between the sensory and motor neurons for distant transmission of Impulses.
- Found in CNS
- Connect Sensory and Motor Neurones
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REFLEX ACTIONS
- It is the automatic response of the body to a stimulus.
- In reflex action the message from the sensory neurones is passed to the spinal chord instead of brain.
- Spinal Chord sends the message to the effectors and produce a response
Example: Knee Jerk Reflexes,
- Touching hot object, Sudden closure of light with bright light
- It is rapid
- It is quick Automatic, Instantaneous without conscious thoughts
Stimulus
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Receptor
| Sensory neurones |
Spinal Chord
Motor neuronesEffector
Response
SYNAPSE
Message is transmitted by chemicals
BRAIN – It is the Central information processing organ of our body, and acts as the command and Control System.
CEREBRUM (Cerebral Hemisphere) – It is nearly 80% part of the brain- Consciousness
- Memory
- Intelligence
- Language
- Muscle Coordination
- Balance
- Unconscious Activities like Heart Rate, Breathing.
- Gut Movement
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Coordination and control – The nervous system
GCSE OCR GATEWAY BIOLOGY : Coordination and control – The nervous system COMPLETE REVISION
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GCSE OCR GATEWAY BIOLOGY : Coordination and control – The nervous system COMPLETE REVISION
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BRAIN SCAN
Magnetic Resonance Imaging (MRI) helps to take the Images of different parts of the brain and relating it with loss of functions of the individual
Problems
- Brain is complex
- Skull protects the brain
- Thousands and neurones and neurotransmitter are involved
- The functions of different parts is still not understood.
- Drugs do not reach the brain
Eye – It is lodged in orbit of skull, hollow, spherical organ, about 2.5 cm in diameter and about 6-8gram in weight
ACCOMMODATION- Ability of eye to adjust the focal length of the lens to make clear image of the objects lying at varying distances. It is a reflex mechanism and is done with the help of ciliary muscles and suspensory ligament.
For distant vision, ciliary muscle relax making the suspensory ligaments tensed which inturn make the lens thin so that the image is focussed on the retina.
For near vision, ciliary muscle contract making the suspensory ligaments to slack which inturn make the lens thick so that the image is focussed on the retina.
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DEFECTS OF VISION
MYOPIA- Short sightedness
- The image falls in front of the retina of the eye.
- Eye ball gets elongated
- corrected by concave lens
HYPERMETROPIA
- Long sightedness
- The image falls behind the retina of the eye.
- Eye balls gets shortened
- corrected by convex lens
NEW EYE TECHNOLOGIES
Contact Lenses- Lenses are placed on the surface of the eye.
- Includes soft, silk and disposable lenses
- Can be used by any person at any age
- Laser is used to change the thickness or the curve of the cornea so that defects of vision can be corrected.
- Can be done on adults after the growing age.
- It involves either replacing the faulty lens or inserting the correct one with the faulty one.
- Include damage risk to the eye.
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