Nervous System Part 3 Reflex Arc Cerebral cortex ANS Divisions

Reflex Arc Parts of a Reflex Arc: –Sensory neuron receptor (#2 in picture) –CNS integrating center (#3) –Motor neuron effector (#4) Other things in picture, but not part of reflex arc: #1 = stimulus #5 = response

What is a reflex? Autonomic response to changes in/out of body Reflexes help maintain homeostasis Examples: resp. rate, swallowing, sneezing, coughing, vomiting, knee-jerk

Cerebral Cortex What is it? –Thin layer of gray matter on outside of cerebrum –Contains 75% of all neuron cell bodies in entire Nervous System

3 major areas of Cortex Motor Areas –Control specific muscles Sensory Areas –Receive all info from skin receptors and specialized nerves Association Areas –Analyze/interpret sensory info

Cerebral Cortex What is the significance of convolutions? –Increase SA which increases amount gray matter and all higher order abilities

ANS Autonomic nervous system Regulates visceral activities –Smooth muscle, cardiac muscle, glands

Movie Clips Grumpier Old Men Princess Bride

Sympathetic ANS Fight or Flight Stress, anger, exercise Major release of EPI (adrenaline)

Sympathetic actions Increased heart rate Increased cardiac output Pupils dilate (all senses increase) Increased sweating (not palms) Increased blood pressure Increased blood glucose Increased respiratory rate

Sympathetic actions Increased CR Increased mental activity (no memories) Increased rate of blood clotting Increased blood flow to active muscles Decreased blood flow to digestive organs General vasoconstriction (= less blood loss) Decreased digestion

Parasympathetic ANS “Rest and Digest” Decreased heart rate Decreased cardiac output Pupils constrict (all senses decrease) Palms sweat All decrease… General vasodilation Increased digestion, salivation, defecation, urination