Lecture Notes: Exam Overview and Peripheral Nervous System

Exam Overview

• Exam Three:
  • Considered one of the more challenging exams along with Exam Four.
  • Covers muscle and nerve physiology, challenging mechanistic processes.
  • Average score: 69%, lower than Exams One and Two.
• Exam Four:
  • Expected to be equally challenging.
• Exam Five:
  • Focuses on Special Senses.
  • Considered more straightforward.
  • Contains 20-25% review material, rest new content on Special Senses.
  • Opportunity to drop the lowest exam score if this exam or the final is not needed.

Quizzes and Preparations

• Quizzes Due: Quiz 9 and Quiz 11 by Friday, 11:59 PM.
• Suggestion: Attend SI sessions and review sessions to prepare.

Weekly Schedule

• Current Focus: Peripheral nervous system (PNS) today and Wednesday.
• Next Week: Nerve physiology.
• Following Week: Conclude nerve physiology with an online lecture.
  • No class the Wednesday before the exam due to instructor being out of town.
  • Possible review session scheduled.

Peripheral Nervous System (PNS) and Reflexes

• PNS links to CNS; crucial for sensory and motor functions.
• Autonomic Nervous System (ANS): Part of PNS, controls homeostatic activities.
• Reflexes:
  • Pupil dilation/constriction as a reflex action.
  • Reflex examples: muscle spindle (length), Golgi tendon organ (tension).
  • Other reflexes: baroreceptor reflex (blood pressure regulation), micturition reflex (urination control).

Autonomic Nervous System (ANS) Divisions

• Sympathetic Nervous System (SNS):
  • "Fight or flight" response, increases heart rate, respiration, blood pressure, and muscle perfusion.
  • Reduces blood flow to skin and digestive tract.
• Parasympathetic Nervous System (PSNS):
  • "Rest and digest" response, calming effect, reduces heart rate, oversees digestion and waste elimination.
  • Operates via cranial-sacral outflow.

Enteric Nervous System

• Located in the digestive tract, operates largely independently.
• Regulates motility and secretion, important for digestion and absorption.

Neural Pathways

• Sympathetic Pathways:
  • Thoracolumbar division.
  • Three main presynaptic pathways: spinal nerve, sympathetic nerve, splanchnic nerve.
• Parasympathetic Pathways:
  • Craniosacral division.
  • Includes cranial nerves and sacral nerves.

Reflex Arc Comparison

• Somatic Reflex Arc:
  • Single nerve fiber, skeletal muscle (voluntary).
  • Neurotransmitter: acetylcholine.
• Visceral Reflex Arc (Autonomic):
  • Involves two nerve fibers; synapse at a ganglion.
  • Neurotransmitter: acetylcholine or norepinephrine.
  • Can be excitatory or inhibitory.

Study Recommendations

• Review lecture slides and prepare for upcoming material.
• Attend TA and SI sessions for better understanding of complex material.

Note

• The importance of setting time aside to study challenging content in this unit to avoid falling behind.