Key Terms
Every sensory system follows the same sequence
Reception -> Transduction -> Encoding -> Perception
Reception
Stimulus activates a sensory receptor. Transduction: receptor converts that stimulus into an electrical signal (receptor
Encoding
The nervous system encodes type, location, duration, and intensity. Perception: the BRAIN interprets the signal.
Special senses
Olfaction, gustation, equilibrium, vision, hearing.
General senses (somatosensation)
Temperature, pain, pressure, vibration, proprioception, kinesthesia.
Epidermis
Outermost, thin, no blood supply, barrier function. Dermis: thicker, blood vessels, glands, follicles, most receptors li
Hypodermis
Fatty layer below dermis; anchors skin to bone and muscle; about 50% of body fat; routes nerves and blood to dermis.
Muscle spindles
Detect stretch/lengthening of muscles. Golgi tendon organs: detect force of muscle contraction.
Salty
Na+ ions enter the taste neuron directly and depolarize it. Sour: acids; H+ concentration increases, depolarizing the ne
Olfactory epithelium
5 cm2 patch in the back of the nasal cavity. About 12 million olfactory receptors.
Taste signals travel
Tongue -> medulla -> thalamus -> primary gustatory cortex. Olfactory signals travel: olfactory epithelium -> olfactory b
Outer ear
Collects and funnels sound waves. Tympanum (eardrum): vibrates in response to pressure waves.
Oval window
Entry point to fluid-filled inner ear. Cochlea: snail- shaped, fluid-filled; contains the basilar membrane and organ of
Inner hair cells
~3,500; arranged in one row; primary auditory receptors; 90% of afferent neurons carry their signals. Outer hair cells:
Utricle and saccule
Detect straight-line acceleration including gravity. Hair cells lie under a gelatinous layer embedded with calcium carbo