1. Sense of Touch

2. Touch and Pressure Often called cutaneous sensations because most of their receptors are in the skin Governed by mechanoreceptors of different types which are widely distributed

3. Meissner’s Corpuscles Primary receptors for touch are Meissner’s corpuscles; small oval capsules of connective tissue containing the dendrites of two or more neurons If connective tissue is moved, even slightly, by a mechanical disturbance, it contacts the dendrites which respond by generating a nerve impulse

4. Meissner’s Corpuscle

5. Meissner’s Corpuscles Most abundant in the skin of the fingers, palms, soles, lips, and external genitals The Sensory Homunculus represents the density of touch receptors in different areas of the body

8. Merkel’s discs Merkel’s discs are another type of touch receptor that are found only in thin skin. Widespread and sensitive to sustained pressure Often associated with hair follicles

9. Pacinian Corpuscles The receptors responsible for the sensation of pressure are known as Pacinian corpusles They consist of a knoblike ending of a single sensory neuron surrounded by layers of connective tissue that resemble the layers of an onion

10. Pacinian Corpuscles

11. Temperature The sensation of temperature is detected by free nerve endings in the skin These are simply the exposed ends of dendrites and it is not well understood how they generate nerve impulses Extreme temperatures will also trigger pain receptors (below 10 and above 45 degrees Celsius)

12. Pain Pain is a necessary evil that warns the brain when a homeostatic imbalance needs attention Pain is detected by branching dendrites of sensory neurons that end freely throughout the skin, muscles, and most visceral organs It is thought that these dendrites are sensitive to chemicals produced as cells are damaged; the greater the cellular damage, the greater the sensation of pain

13. Pain Pain may also be caused by the overstimulation of any receptor Visceral pain receptors tend to respond only to widespread disturbances giving sensations such as heartburn, intestinal cramps, headaches, etc. Visceral pain is also harder to trace to its source because major nerve pathways are shared with other parts of the body

14. Referred Pain

15. Pain The intensity of pain can be controlled by use of drugs: Analgesics, which interfere with the transmission of impulses, Anesthetics, which produce an absence of sensation, Surgery, accupuncture, hypnosis, massage, and controlled breathing are also effective for certain cases

16. Body Position Receptors that make you aware of body position are known as proprioceptors These provide information on the degree of muscle contraction, the amount of tension in tendons, position of a joint, and the position of the head relative to the ground Muscle spindles monitor the length of a muscle during contraction

17. Body Position Your brain keeps track of movements and combines these with information from the middle ear to determine the position of the body and it’s various parts in space