Sense Organs
SENSE ORGANS
RECEPTORS (Sense organs) * Transducers of specific forms of kinetic energy * Change mechanical, electrical, thermal, chemical, or radiant energy into nerve impulses in sensory neurons
Two major categories: * GENERAL RECEPTORS * Often exist as individual cells or receptor units * Widely distributed throughout the body * Most numerous such as: * touch, temperature, and pain: and * to initiate various reflexes necessary for maintaining homeostasis * SPECIAL RECEPTORS * Large and complex organs * Localized grouping of specialized receptors * Have limited distribution and mostly paired * Function to produce vision, hearing, balance, taste, and smell; and * to initiate reflexes important for homeostasis.
CLASSIFICATION OF RECEPTORS: * Classified according to: * Location; * Stimulus detected; and * Structure
Classification by Location: * Somatic Receptors – provide information about the external environment * Exteroceptors: (cutaneous receptors) * Located on or very near the body surface * Respond mostly to external stimuli * Detect pressure, touch, pain, and temperature * Proprioceptors: * Provide information about the skeletomuscular system * Less numerous and more specialized * Limited to skeletal muscles, joint capsules, and tendons * Visceral Receptors – monitor the internal environment and provide information about the olfactory and gustatory information from the environment * Visceroceptors (enteroceptors): * Located internally, often within the body organs (viscera) * Activated by pressure, stretching, and chemical changes * Involved in sensations of hunger and thirst
Classification by stimulus detected * Five categories based on the types of stimuli that activate them: * Mechanoreceptors:
RECEPTORS (Sense organs) * Transducers of specific forms of kinetic energy * Change mechanical, electrical, thermal, chemical, or radiant energy into nerve impulses in sensory neurons
Two major categories: * GENERAL RECEPTORS * Often exist as individual cells or receptor units * Widely distributed throughout the body * Most numerous such as: * touch, temperature, and pain: and * to initiate various reflexes necessary for maintaining homeostasis * SPECIAL RECEPTORS * Large and complex organs * Localized grouping of specialized receptors * Have limited distribution and mostly paired * Function to produce vision, hearing, balance, taste, and smell; and * to initiate reflexes important for homeostasis.
CLASSIFICATION OF RECEPTORS: * Classified according to: * Location; * Stimulus detected; and * Structure
Classification by Location: * Somatic Receptors – provide information about the external environment * Exteroceptors: (cutaneous receptors) * Located on or very near the body surface * Respond mostly to external stimuli * Detect pressure, touch, pain, and temperature * Proprioceptors: * Provide information about the skeletomuscular system * Less numerous and more specialized * Limited to skeletal muscles, joint capsules, and tendons * Visceral Receptors – monitor the internal environment and provide information about the olfactory and gustatory information from the environment * Visceroceptors (enteroceptors): * Located internally, often within the body organs (viscera) * Activated by pressure, stretching, and chemical changes * Involved in sensations of hunger and thirst
Classification by stimulus detected * Five categories based on the types of stimuli that activate them: * Mechanoreceptors: