Ch 13 – PNS & Reflex Activity

Learning Objectives1. Describe the major responsibilities of the PNS.2. Recognize that reaction times are controlled with the

assistance of the PNS.3. Discuss the 5 types of sensory receptors and what they

do.4. Identify and explain the structures and function of the

eye.

The brain of an average-sized adult weighs about three pounds, yet the amount of information it contains is amazing!

Read 442, 445 – 464. Review eye anatomy & learn structures and functions (complete 11 terms last slide).

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.

PNS• Sensory (afferent)

division• Motor (efferent)

division

PNS•Provides links to and from the _________ environment•Conducts these impulses from receptors to the _____

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

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 ___________

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

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

Eye Anatomy Label your practice diagram

cornea

pupil

iris

lens

aqueous humor

blind spot

optic nerve

vitreous humor

sclera

choroid

retina

Homework & Study Practice

1. cornea2. pupil3. iris4. lens5. aqueous humor6. vitreous humor7. sclera8. choroid9. retina10. optic nerve11. blind spot

Instructions: Describe each structure and explain its function