The document discusses the somatic and special senses. It describes the 5 types of receptors and how sensation and projection work. It then discusses the somatic senses of touch, temperature, pain, taste and smell. It details the structures involved in hearing, equilibrium and sight such as the outer, middle and inner ear, eye structures like the retina and visual receptors of rods and cones.

1. CHAPTER 10: SOMATIC AND SPECIAL SENSES

2. Receptors and Sensations 5 Types of Receptors a) chemoreceptors b) pain receptors c) thermoreceptors d) mechanoreceptors e) photoreceptors

3. Sensation - a feeling that occurs when impulses are interpreted by the brain Projection - the brain causes these feelings to seem to come from the area being stimulated Sensory adaptation - impulses fail to send signal due to continuous stimulation

4. Somatic Senses  senses that are associated with the skin, muscles, joints, and organs 1. Touch and Pressure Senses a) sensory nerve fibers A b) Meissner’s Corpuscles - sensitive to the motion of objects that barely contact the skin B C

5. c) Pacininan Corpulscles - stimulated by heavy pressure and deep pressure 2. Temperature Senses - are 2 types of free nerve endings - heat receptors - cold receptors

6. 3. Sense of Pain - are free nerve endings that are widely distributed throughout the skin and internal organs Visceral Pain - widespread pain from the internal organs - can cause referred pain - pain feels like it is coming from other part of the body

7. Sense of Taste - occurs on the taste buds on the tongue taste buds - taste bud made up of: - taste cells - taste pores - taste hairs taste cell taste hair taste pore

8. Sense of Smell  olfactory sense olfactory bulb olfactory receptor cells - chemical must enter the nose as a gas and be partially dissolved in fluid to smell - chemicals detected by the olfactory receptor cells , sent to the olfactory bulb , and then sent to the brain via the olfactory tract - each olfactory receptor cell can detect a different type of smell

9. - chemicals must be dissolved in a watery fluid for the taste cells to detect stimuli - the sense of smell also helps us taste our food 5 Taste Sensations a) sweet b) sour c) salty d) bitter e) umami

10. Sense of Hearing 1. External Ear pinna external auditory meatus - functions to collect sound waves

11. 2. Middle Ear tympanic membrane malleus incus stapes auditory tube

12. 3 smallest bones in the body

13. 3. Inner Ear Inner ear

14. semicircular canals cochlea

15. - semicircular canals - involved with equilibrium - cochlea - interprets sound waves Organs of Corti - sound vibrations move hairs  stimulates nerves  sends to brain Sense of hearing 3. Inner Ear

16. Sense of Equilibrium Static Equilibrium - help maintain stability

17. Dynamic Equilibrium - detects motion of the head - helps maintain balance while moving

18. Sense of Sight Visual Accessory Organs 1. eyelids 2. conjuctiva - membrane that lines inner surface of eyelids 3. extrinsic muscles - 6 muscles that moves the eyeball

19. eyelid conjuctiva muscle muscle

20. 4. lacrimal gland - secretes tears to moisten and lubricate eye - decreases chance of eye infection

22. Structure of the Eye 3 Layers 1. Outer Tunic a) cornea - transparent covering over the eye b) scelera - white part of the eye c) optic nerve

23. 2. Middle Tunic a) choroid coat - contains blood vessels - contains melanocytes to absorb excess light b) ciliary body - moves the lens so it can focus c) lens - very flexible so it can focus on objects - accomodation - the adjustment of the lens

24. d) iris - colored part of the eye - allows a certain amount of light into the eye e) pupil - opening into the eye

25. 3. Inner Tunic a) retina - contains photoreceptors - fovea centralis - point on retina where the light rays focus - produces the sharpest vision - optic disk - place where nerve fibers leave retinal and become optic nerve - causes the blind spot b) vitreous humor - fluid inside the eyeball

26. Visual Receptors 2 Types a) rods - 100X more sensitive than cones - allow us to see in dim light b) cones - allows us to see in color - gives sharper vision

27. Visual Pigments Rhodopsin - color vision seems to be related to the presence of 3 sets of cones containing different light-sensitive pigments a) red b) blue c) green