General Senses

Types of Stimuli

• Mechanical – touch, hearing, balance (movement)

• Thermal – hot, cold 

• Electromagnetic – vision

• Chemical – taste, smell

Visceral Sensations

• Miscellaneous category of interior body sensations

• Vague and poorly localized

• Examples: hunger, thirst, visceral stretch (GI tract, urinary system)

Touch and Pressure 

• Tactile sense – sensation of something in contact with the surface of the body

• Pressure – sensation of something pressing on the body surface

• Different touch and pressure receptors produce sensations of light contact, deep pressure, vibration, or hair movement (partly unconscious)

Temperature

• 2 types of temperature receptors:

  • Superficial – receptors in the skin; detect changes in skin temperature

  • Central – receptors in the hypothalamus; monitor temperature of the blood

Pain

• Pain receptors = nociceptors

  • Widely distributed inside and on the surface of the body

  • Not present in the brain

  • May be simple nerve endings or more specialized structures

  • Purpose: protect the body from damage

Pain Processes

1. Transduction – conversion of stimulus into nerve impulse (at the nociceptor)

2. Transmission – transmission of nerve impulses via sensory nerve fibers

3. Modulation – modulation of the nerve impulse (at the spinal cord)

4. Perception – conscious perception (at the brain)

Classification of Pain

• Superficial (outside)

• Deep (deeper in)

• Visceral (inside body- organ pain)

• Acute (rapid and intense)

• Chronic (slow, longer lasting)

Proprioception

• Sense of body position and movement

• Includes:

  • Movements of limbs

  • Positions of joints

  • State of contraction of muscles

  • Tension exerted on tendons and ligaments