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• Main types of senses

  • General
  • Special
• Touch


  • The ability to sense pressure, vibration, temperature, pain, and other tactile stimuli
  • The receptors for touch are found in the skin
• Aspects of the sense of touch

  • Mechanoreception (detection of pressure and vibration)
  • Nociception (detection of pain or harmful stimuli)
  • Thermoception (detection of temperature changes)
• Special senses


  • Have specialized sense organs that collect sensory information and convert it into nerve impulses
  • Equilibrium (Ears)
  • Hearing (Ears)
  • Sight (Eyes)
  • Smell (Nasal Cavity)
  • Taste (Tongue)
• Equilibrium

  1. The ear has many patches that contain the otolithic membrane and hairs embedded into it

  2. When the head moves, the otolith (stones made of calcium) also move, following the pull of gravity

  3. This makes the gel-like membrane to also move, bending the hairs inside it

  4. The bending activates the hair cells to send signals along the vestibulocochlear to the cerebellum, informing the position of the head

  
• Hearing


  1. Sound waves enter the ear through the ear canal and travel to the eardrum

  2. The sound waves strike the eardrum and make it vibrate

  3. The vibrations then travel through the three bones (incus, malleus, and stapes) of the middle ear, which amplify the vibrations

  4. From the middle ear, the vibrations to the cochlea in the inner ear

  5. The cochlea is a tube filled with liquid

  6. The liquid moves in response to the vibrations, causing hair cells lining the cochlea to bend

  7. Hair cells send nerve impulses to the auditory nerve, which carries the impulses to the brain, interpreting what we hear

  
• Sight

  1. Light passes first through the cornea

  2. Light then passes through an opening called the pupil

  3. The iris causes the pupil to narrow in bright light and widen in dim light

  4. The light then passes through the lens, which refracts the light even more and focuses it on the retina at the back of the eye, as an inverted image

  5. The retina contains two types of photoreceptors: rod cells (particularly sensitive to low levels of light) and cone cells (sensitive to light of different colors and allow color vision)

  6. The rods and cones convert the light that strikes them to create nerve impulses

  7. The nerve impulses travel to the optic nerve then towards the brain (cerebrum), which interprets messages from both eyes and tells us what we are seeing
• Smell


  • The ability to detect and identify molecules in the air
  • Olfactory nerves are present in the nasal cavity and the nerve endings sense the chemicals in the air and interpret them as odor
• Taste


  • The ability to perceive flavor
  • Taste receptors are found in tiny bumps on the tongue called taste buds
  • Taste receptor cells make contact with chemicals in food through tiny openings called taste pores
  • When certain chemicals bind with taste receptor cells, it generates nerve impulses that travel through nerves to the central nervous system

  
• Categories of animals based on thermoregulation

  • Warm-blooded (homeotherms)
  • Cold-blooded (poikilotherms)
• Homeotherms


  • Organisms that maintain their body temperature at a constant level
  • Warm-blooded animals
  • Can generate heat through consumption of food and metabolism
  • Usually have an internal body temperature of 35-40 degrees Celsius
  • Some warm-blooded animals hibernate in cold conditions
• Poikilotherms


  • Organisms that cannot regulate their internal body temperature with the change in the environment
  • Cold-blooded animals
  • Need heat from the environment to survive
  • Do not have a specific body temperature as they match the environment
  • Cold-blooded animals hibernate (in cold conditions) and aestivate (in hot conditions)
• Ways the body generates heat

  • Muscles and liver
  • Ingesting hot food or water
  • Conduction (laying on a warm area)
  • Radiation (sun rays)
• Ways the body loses heat

  • Conduction and convection
  • Sweating and micturition
  • Breathing
• Adaptive properties for survival in harsh environments

  • Fur (polar bear)
  • Fat storage (seal)
  • Migration (birds)