10.1-10.5 Senses

Two categories of sensory receptors:1. somatic-touch, pressure, temperature,

pain2. Special senses that are important for

smell, taste, hearing, equilibrium, and vision

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Types of Receptors-chemoreceptors-sense changes in chemicals-pain-sense tissue damage-thermoreceptors-change in temperatures-mechanoreceptors-change in pressure or movement-photoreceptors-light stimuli

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Sensations vs. Projection-Sensations are feelings that occur when the

brain interprets sensory impulses.-projection allows a person to figure out

where that sensation came fromex: ears hear, nose smells

-You have the ability to ignore certain stimuli-sensory adaptation

-unresponsive receptors or signal does not get to cerebral cortex

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Type 1: Somatic Senses A. Associated with receptors in the skin, muscles, joints, and viscera (organs within the body cavities)B. Touch/Pressure, Temperature, and Pain

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Touch and Pressure Senses-Receptors

1. Free nerve endings-in skin2. Meissner’s corpuscles-flattened

connective tissue1. Abundant in hairless areas/very

sensitive3. Pacinian corpuscles- They function to

detect deep pressure. 1. Muscle, tendons, joints, subcutaneous layer

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Temperature Senses -warm receptors and cold receptors (free nerve

ending types)-adapt very rapidly-respond in different temperature ranges

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Sense of PainVisceral pain receptors are the only receptors

in the viscera that produce sensations.a. Referred pain-pain may feel

like it is coming from one area other than the area that is

stimulated. b. occurs because of the

common nerve pathways leading from skin and internal organs.

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Pain Nerve Fibersa. Fibers conducting pain impulses away from their source are either acute pain fibers or chronic pain fibers.b. Acute pain fibers are thin, myelinated fibers that carry impulses rapidly and cease when the stimulus stops.c. Chronic pain fibers are thin, unmyelinated fibers that conduct impulses slowly and continue sending impulses after the stimulus stops.

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d. Pain impulses are processed in the gray matter of the spinal cord.

e. Pain impulses are conducted to the thalamus (first to be aware of pain), hypothalamus, and cerebral cortex (determine pain intensity, locate source, mediate response..

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Sense of Smell A. Olfactory Receptors

1.     chemoreceptors2. Smell and taste work

together-food selection

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Olfactory Organs 1. are located in the upper nasal

cavity.2. The receptor cells are bipolar

neurons with hairlike cilia covering the dendrites. The cilia project into the nasal cavity.

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Olfactory Stimulation 1. Scientists are uncertain of how

olfactory reception operates but believe that each odor stimulates a set of specific protein receptors in cell membranes.

2. The brain interprets different receptor combinations as an

olfactory code.3. Olfactory receptors adapt quickly

but selectively.

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Headaches

• Tension headache-due to stress, fatigue, emotional tension, anxiety– Caused contraction of skeletal muscles in

forehead, side of head, and back of neck

• Vascular headache-constriction and dilation of cranial blood vessels

• Migraine-form of vascular headache– BV constrict and produce blood deficiency

Taste

Taste buds are the organs of taste and are located within papillae of the tongue and are scattered throughout the mouth and pharynx.-papillae-tiny elevations

Taste Receptors

1. Taste cells are modified epithelial cells that function as receptors. (Each taste bud has 50-150 of these)

2. Contain the taste hairs that are the portions sensitive to taste.

Sweet-near the tipSour-lateral edgesSalt-tip and upper

portion of tongueBitter-back of tongue-this is up for debate