1. Aaron Wu, Kat So, Joanna Gochuico, and Chris Evans
Reflexes
Aaron Wu, Kat So, Joanna Gochuico, and Chris Evans

2. History of Reflexes
Reflexes were considered important since the time of Descartes (1600’s)
Studies involved physiologists, neurologists, and psychologists.
First to really study reflexes were René
Descartes and Thomas Willis.

3. BELIEFS
Decartes: When a sensation reached the pineal gland, it serves to orientate the “spiritus animus” in the right direction, to cause a reaction.
Animal spirit = nerve impulse
Spirit penetrate brain via very fine pores.
Willis: nerve impulses journeyed to and from the brain, and that “animal spirits” were reflected back toward the periphery
3 types of movement

4. Decartes and De Homine
De Homine’s :1st european book on physiology by Decartes (1662)
Shows infant looking at a fire (A) and withdrawing his left foot (B). The 'pain' message is represented going to the pineal gland (F).

5. Reflexes Reflex: an automatic motor response to a specific stimulus
Message route = PNS  CNS
Purpose: help preserve homeostasis through rapid adjustments in function of organs systems

6. Simple Reflexes Monosynaptic: most rapid, requires one synapse
Stretch Reflex
Receptors = muscle spindles (m. fibers)
Stimulus = increase muscle length
Motor response= contraction
Regulates muscle length
Automatic response to maintain posture and balance by adjusting muscle tone
Ex. Knee Jerk Reflex

7. Complex Reflexes Polysynaptic Reflexes: Withdrawal Reflexes:
More synapses = longer delay between stimulus and response
Withdrawal Reflexes:
Move stimulated part away from source
Strongest reflex initiated by pain
Flexor reflex: reflex affecting muscle of limb
ex. Hand to hot pan
Reciprocal Inhibition:
One set of motor neurons is stimulated, those controlling antagonistic muscles are inhibited

8. Control of Spinal Reflex
Sensitivity of reflex can be modified
Higher centers of the brain can stimulate or inhibit interneuron's and motor neurons involved
Descending fibers have inhibitory effect on spinal reflexes
Babinski sign (+) = fanned toes, (-) = plantar reflex
If signs return in adulthood, CNS injury
Descending pathways from brain facilitate, inhibit, fine- tune established reflexes

9. Reflex Arc (pg 273)

10. Types of Reflexes Somatic Reflexes: skeletal muscles.
Autonomic Reflexes: Smooth and Cardiac muscle.
Ex. Digestion, blood pressure
Innate Reflex Actions: Involuntary Action
Withdrawal Reflex: Response generated without brain analyzing stimulus fully
Stretch Reflex: When a muscle is struck, causes contraction
For a quiz - I was thinking to give two examples and ask them which type of reflex it is.
Touching a hot object - withdrawal
Knee Jerk reflex - stretch
Blinking when bright - involuntary

11. Bibliography
mer05/JerryHalpern/Reflexes.pdf
y/factfiles/reflexes/reflexes.shtml
y_guide/reftext/html/nerv_sys_fin.html
sp?LC_Docs_ID=3155
Human Anatomy Textbook Pg