Senses and Receptors

• Receptors


  
  

  • They detect changes in your body's environment and send that information to other parts of the body
  • They receive stimuli
• Stimulus


  • Is any information that your body receives that might cause it to respond
  • The easiest stimuli to identify are those that we respond to physically
• Responding to change

  • Within our bodies, we regularly respond to change without consciously acknowledging a stimulus and response

  Examples:

  • Something in your body is communicating with your brain to tell you when to find food and water when hungry or thirsty
  • Our bodies are constantly monitoring the number of bacteria, viruses and fungi we have and fighting harmful microorganisms
• Five sense

  1. Sight
  2. Hearing
  3. Smell
  4. Taste
  5. Touch
• Five Sense Organs

  1. Eyes
  2. Ears
  3. Tongue
  4. Nose
  5. Skin
• Sight and Eyes

  • Tells us more about the world than any other sense
  • Pupils change size to control how much light enters the eye
  • The photoreceptor cells at the back of the eye transform the light into nerve signals for the brain
  • The information from your eyes transfers to your brain which then tells you what your seeing
• Structures of the eye

  Iris: Controls the amount of light entering the eye

  Cornea: Bends incoming light

  Lens: Focuses incoming light

  Photoreceptor: Changes Light into nerve signals

  Optic nerves: allows nerve impulses to travel to the brain
• Photoreceptor cells are located in the retina
• A crocodile's eye has an elliptical (oval-shaped) pupil, which helps to protect its sensitive retina from the bright light of day
• Hearing and Ears

  • Vibrations in the air cause your eardrum to vibrate
  • The vibrations are transferred to the bones of the middle ear and converted into nerve impulses
  • The brain interprets the information, telling you what you are hearing
• Structures of the Ear

  Ear canal: Where sound enters through

  Eardrum: A membrane that vibrates due to the vibration of the air

  Middle ear: Changes vibration particles that pass through into nerve impulses

  Cochlea: Contains fluid that moves due to the vibrations coming from the middle ear. This motion becomes an electrical signal that is passed to nerve cells

  Auditory nerve: Allows nerve impulses to travel to the brain
• Taste and Tongues

  • Tongues are covered with thousands of tiny taste buds that contain special receptor cells that react to the chemicals in food
  • Taste buds can recognise basic kinds of taste such as Sweet, Sour, Salty, Bitter
  • When eating or drinking, the information from taste receptor cells is sent to the brain through nerves, telling you what flavours you are tasting
• Smell and Noses

  • Our perception of smell is based on the receptor cells found in our nostrils
  • These receptors detect chemicals in the air and then send messages to the brain, which interprets the messages and tells us what we are smelling
  • Smell is closely linked to taste
• Structures of the Nose

  Nostrils: Allows air to enter

  Nasal Sinuses: Provides mucus which helps to trap bacteria and small particles

  Smell receptors: Stimulate the olfactory bulb, which sends messages to the brain

  Nasal cavity: Allows air to move through to the back of the throat

  Trachea: Allows air to travel to the lungs
• Touch and Skin

  • Touch is felt all over the body
  • The bottom layer of the skin (dermis) contains many nerve endings that can detect heat, cold, pressure and pain
  • Information is collected by these receptors and sent to the brain for processing and reaction
• Structures of the Skin

  Hair

  Sweat Pore

  Papillae

  Epidermis

  Capillaries near the surface of the skin

  Dermis

  Sweat Gland

  Hair Root

  Blood Vessels

  Subcutaneous fat layer