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Notes for Ch. 10 (Somatic and Special Senses) Introduction • General senses o Receptors that are widely distributed throughout the body o Skin, various organs and joints • Special senses o Specialized receptors confined to structures in the head o Eyes, ears, nose and mouth Receptors, Sensation, and Perception • Sensory receptors • Specialized cells or multicellular structures that collect information from the environment • Stimulate neurons to send impulses along sensory fibers to the brain • _______________________ – A feeling that occurs when brain interprets sensory impulses. • _______________________ – A person’s view of the stimulus; the way the brain interprets the information Receptor Types • _______________________ – Respond to changes in chemical concentrations • _______________________– Respond to tissue damage • _______________________–Respond to changes in temperature • _______________________–Respond to mechanical forces • _______________________–Respond to light Touch and Pressure Senses • _______________________ o Common in epithelial tissues (most common receptor in the body) o Simplest receptors o Sense itching • _______________________ o Abundant in hairless portions of skin and lips o Detect fine touch; distinguish between two points on the skin • _______________________ o Common in deeper subcutaneous tissues, tendons and ligaments o Detect heavy pressure and vibrations Temperature Senses • _______________________ o Sensitive to temperatures above 25oC (77o F) o Unresponsive to temperature above 45oC (113oF) • _______________________ o Sensitive to temperatures between 10oC (50oF) and 20oC (68oF) • _______________________ o Respond to temperatures below 10oC o Respond to temperatures above 45oC Sense of Pain Detected by _____________________________________, Widely distributed Nervous tissue of _____________________ lacks pain receptors – brain surgery does not hurt! Stimulated by tissue damage, chemical, mechanical forces, or extremes in temperature Adapt very little, if at all Visceral Pain o ____________________________ are the only receptors in viscera whose stimulation produces sensations o Pain receptors may feel as if coming from some other part of the body -- known as _______________________________ o This convey information that includes the sense of fullness after eating a meal as well as the discomfort of intestinal gas and the pain that signals a heart attack o Referred pain may occur due to sensory impulses from two regions following a common nerve pathway to brain Pain Nerve Pathways o _______________________________ Thin, myelinated, Conduct impulses rapidly, Associated with sharp pain, Well localized o _______________________________ Thin, unmyelinated , Conduct impulses more slowly, Associated with dull, aching pain, Difficult to pinpoint Regulation of Pain Impulses o _____________________________ – Allows person to be aware of pain ____________________________________ Judges intensity of pain Locates source of pain Produces emotional and motor responses to pain o Pain inhibiting substances:_____________________________________________________________________ Special Senses Sensory receptors are within large, complex sensory organs in the head _____________________ in olfactory organs _____________________ in taste buds ____________________________________ in ears _____________________ in eyes Sense of Smell • _________________________________ o Chemoreceptors o Respond to chemicals dissolved in liquids • _________________________________ o Contain olfactory receptors and supporting epithelial cells o Cover parts of nasal cavity, superior nasal conchae, and a portion of the nasal septum • Once olfactory receptors are stimulated, nerve impulses travel through: o Olfactory nerves _________________________ olfactory tracts ________________________________ o (for emotions) and ____________________________________ (for interpretation) Olfactory Stimulation o Olfactory organs located high in the ________________________________ above the usual pathway of inhaled air o Olfactory receptors undergo sensory adaptation rapidly o Sense of smell drops by _____% within a second after stimulation Sense of Taste • _____________________________ • Organs of taste • Located on papillae of tongue, roof of mouth, linings of cheeks and walls of pharynx • ________________________________ • Chemoreceptors • ___________________________ – modified epithelial cells that function as receptors o • ___________________________ –microvilli that protrude from taste cells; sensitive parts of taste cells Four primary taste sensations • ___________________ – stimulated by carbohydrates • ___________________ – stimulated by acids • ___________________ – stimulated by salts • ___________________ – stimulated by many organic compounds • Spicy foods activate ______________________________ Taste Nerve Pathways Sensory impulses from taste receptors travel along Cranial nerves_______________________________ ________________________Gustatory cortex (for interpretation) Sense of Hearing • Ear – Organ of hearing • Three (3) sections: o External ear o Middle ear o Inner ear External Ear • ____________________________ – Collects sounds waves • External auditory meatus • Lined with __________________________ glands • Carries sound to ___________________________________ • Terminates with tympanic membrane • ____________________________ –Vibrates in response to sound waves Middle Ear • ____________________________ – Air-filled space in temporal bone • ____________________________ –Vibrate in response to tympanic membrane o ______________________________________________(smallest bones in the body) • Oval window o Opening in wall of tympanic cavity o Stapes vibrates against it to move fluids in inner ear • Auditory Tube o Also known as the _____________________________ o Connects middle ear to throat o Helps maintain equal pressure on both sides of ____________________________________ o Usually closed by valve-like flaps in throat Inner Ear Three (3) parts of labyrinths: • ____________________________ – Functions in hearing • ____________________________ – Functions in dynamic equilibrium • ____________________________ – Functions in static equilibrium Sense of Equilibrium • __________________________________________ • Vestibule • Senses position of head when body is not moving • __________________________________________ • Semicircular canals • Senses rotation and movement of head and body Sense of Sight • Visual accessory organs o Eyelids o Lacrimal apparatus o Extrinsic eye muscles • Eyelid • Palpebra – Composed of four (4) layers: (Skin, Muscle, Connective tissue, Conjunctiva) • ___________________________ – closes eyelid • ______________________________________ – opens eyelid • ___________________________– secrete oil onto eyelashes • • • • • • • • ___________________________ – mucous membrane; lines eyelid and covers portion of eyeball Lacrimal apparatus ____________________________ – Lateral to eye and secretes tears ____________________________ – Collect tears ____________________________ – Collects from canaliculi ____________________________ – Collects from lacrimal sac and empties tears into nasal cavity Extrinsic eye muscles _____________________________ – Rotates eye up and medially • _____________________________ – Rotates eye down and medially • _____________________________ – Rotates eye medially • _____________________________ – Rotates eye laterally • _____________________________ – Rotates eye down and laterally • _____________________________ – Rotates eye up and laterally