Ch 13 – PNS & Reflex Activity

1. The brain of an average-sized adult weighs about three pounds, yet the amount of information it contains is amazing! Ch 13 – PNS & Reflex Activity Read 442, 445 – 464. Review eye anatomy & learn structures and functions (complete 11 terms last slide). Learning Objectives Describe the major responsibilities of the PNS. Recognize that reaction times are controlled with the assistance of the PNS. Discuss the 5 types of sensory receptors and what they do. Identify and explain the structures and function of the eye.

2. Reaction Time Need 2 Volunteers – 1 is the “catcher”; 1 drops ruler between their partner’s fingers (the “dropper”) Instructions for Volunteers: The “Catcher” - Hold your thumb and index finger two inches apart while your partner drops a ruler between them. The “Dropper” – hold ruler vertical and drop it between your partner’s thumb and index finger. The distance the ruler falls before he/she stops it with his thumb and finger indicates their reaction time. Repeat twice. Record the results. Challenge: Try the experiment again while the catcher recites addition or multiplication facts. Compare the results. What happened to the reaction time? Why? NOTE: Our reaction time increases when we are distracted. With all of our senses, an __________ ______ is passed between neurons and travels through the nerves, spinal cord, and brain.

3. PNS • Motor (efferent) division • Sensory (afferent) division • PNS • Provides links to and from the _________ environment • Conducts these impulses from receptors to the _____

4. PNS • The peripheral nervous system includes the _______ that extend from the brain and the spinal cord. ("Peripheral" means "by the surface or the edge“) • Our skin has receptors called ________________ that that allow us to feel pressure and touch, and __________ that allow us to feel heat and cold

5. Other Receptors • We also have receptors that respond to light such as those in the retina of the eye called ________________ • Those that allow us to smell or taste called __________________ • Some that tell indicate potentially dangerous stimuli (i.e., searing heat, extreme cold, excessive pressure) that could result in pain called ___________

6. Sensation versus Perception Survival depends upon sensation and perception. • _________ is the awareness of changes in the internal and external environment • __________ is the conscious interpretation of those stimuli

7. The Eye and Vision • Vision is our dominant sense because ___ of all sensory receptors are in the eyes and nearly ____ of the cerebral cortex is involved in some aspect of visual processing • http://lightisreal.com/lightillusion.html?gclid=CJPjl7Sx5I8CFQdEFQodan3R6w

8. sclera choroid aqueous humor retina cornea pupil optic nerve iris lens blind spot vitreous humor Eye Anatomy Label your practice diagram

9. Homework & Study Practice Instructions: Describe each structure and explain its function • cornea • pupil • iris • lens • aqueous humor • vitreous humor • sclera • choroid • retina • optic nerve • blind spot