Senses, Coordination, Hormones and Homeostasis

Senses
1. The eye
  1. Cornea
    1. Refracts light-bends it as it enters the eye.
  2. Iris
    1. controls how much light enters the pupil.
  3. Lens
    1. Further refracts the light to focus on the retina.
  4. Retina
    1. Contains the light receptors
  5. Optic nerve
    1. carries impulses between the eye and the brain.
Coordination
1. The iris reflex
  1. Low light intensity
    1. Radial muscles of the iris and the pupil are opened wider so more light can enter and reach the retina.
  2. High light intensity
    1. CIrcular muscles of iris contract and the pupil is reduced in size so less light can enter the retina is protected from bleaching.
2. How do we see objects?
  1. 1) The light is refracted when it passes through the cornea boundary and at the lens.
  2. 2) Inverted image on retina
  3. 3) Brain intercepts image as correct way up.
3. Nerve Impulse
  1. Electrical signal that passes along the nerve cells called neurons.
4. Identify motor(effecter), relay(connector) and sensory neurons
5. Descibe a simple reflex arc in terms of receptor, sensory neuron, relay neuron, motor neuron and effector.
  1. The reflex arc is when the receptor receives information through sense and the sensory neurons go the brain and the relay neuron helps to connect to sensory neuron to the motor neuron which goes to the muscle which helps us react
6. Describe a reflex action
  1. It is a means of automatically and rapidly integrating and coordinating stimuli with the responses of effectors.
Hormones
1. Chemical substances that alter the activity of one or more specific target organs. It is secreted by glands. Eg-insulin, adrenaline

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Senses, Coordination, Hormones and Homeostasis

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	Created by Shravani Chingre almost 6 years ago