Homeostasis

• What is homeostatis?


  The regulation of the conditions in our body maintaining stable internal environment
• What does it do?

  Responds to any change in internal or external conditions
• What are the 3 main components in automatic control systems?

  Receptors, coordination centres and effectors
• What is a stimulus?

  A change in your environment than requires a response
• Give some examples of stimuli?

  Light, sound, touch, pressure, pain, chemical or temperature
• What do the receptors do?

  Detect the stimulus when either temp or water is high or low
• What happens after the receptors?

  Receptors send messages to the cns which organise a response to the effector
• Give examples of the central nervous system?

  The brain or spinal cord
• How is the CNS connected to the rest of the body?

  Through sensory and motor neurones

  
• What is an effector?

  Muscles or glands that bring about a response
• What do the muscles and glands do in response?

  Muscles contract and glands secrete chemical substances(hormones)
• What is a sensory neurone?

  Neurones that carry information from the receptors to the cns
• What is a relay neurone?


  Neurones that carry impulses from the sensory to the motor neurones
• What is a motor neurone?


  Neurones that carry information from the cns to the effectors
• What is the nervous system?


  It is what allows you to react to your surroundings
• What is a synapse?


  It is the nerve signal being transferred by chemicals which move across the gap, sending a electrical signal to the next neurone
• What is a reflex arc?

  The passage of the information, that brings around a response

  
• Responses that reduce body temp-

  Hairs lie flat, sweat and blood vessels get wider(vasodilation)
• Responses that increase body temp-

  Hairs stand up, no sweat, shivering and blood vessels constrict(vasoconstriction)
• What is the body's core temp?

  37 degrees c
• What is the sclera?

  The tough supporting wall of the eye

  
• What is the cornea?

  Outer layer, bends light into the eye

  
• What is the pupil?

  The hole in the centre where light enters

  
• What is the iris?

  Controls the diameter of the pupil and how much light enters

  
• What is the retina?

  Contains receptor cells- one sensitive to light intensity and the other is colour

  
• What is the lens?

  Focuses the light into the retina

  
• What is the ciliary muscles and suspensory ligaments?

  Control shape of the lens

  
• What is the optic nerve?


  Carries impulses from the receptors on the retina to the brain

  
• What happens when bright light enters?

  The circular muscles contract and the radial muscles relax, reducing the amount of light that enters
• What happens in dim light?

  The radial muscles contact and the circular muscles relax
• What is long sightedness?

  lens or muscles not powerful enough to bring light to focus on retina. light vocal point is behind retina (convex lens)bottom diagram is with corrective lenses

  
• What is short myopia?

  naturally too powerful lens, unable to focus on distant objects, refracts light too much(concave lens)bottom diagram is with corrective lenses

  
• eye lenses when looking into distance

  for distant objects the light does not have to be refracted by a big angle

  
• eye lenses for near objects

  For near objects the light has to be refracted through a big angle. ciliary muscles contract making the lens thickerlooks like a diamond on its side
• What is the brain made from?

  Millions of interconnected neurones
• What is the brain in charge of?

  It is in charge of our complex behaviours, controls and coordinates everything we do
• What is the cerebral cortex?

  The outer wrinkly layer of the brain, controls consciousness, memory and language

  
• What is the medulla?

  The base, controls unconscious activities like breathing, movement in the intestines and heartbeat

  
• What is the cerebellum?

  At the back, responsible for muscle contraction & balance

  
• what is the hypothalamas

  controls homeostasis and pituitary gland