Human A&PBIO 304 · American River College ← Week 05 pre-work

BIO 304 · Week 05 · Interactive Workbook

PNS & Autonomic Nervous System

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Part 1 of 4 · Recall

Fill in the blanks

Type the term that completes each statement, using the word bank. Pull it from memory first.

Word bank

Dual innervationPreganglionic axonPupilVIII VestibulocochlearX VagusV TrigeminalSomaticPostganglionic NTXII HypoglossalPreganglionic NTOriginIII OculomotorAdrenal medullaI OlfactoryDermatome

  1. smell (sensory only)
  2. most eye movements, pupil constriction, lid
  3. face sensation; muscles of mastication
  4. hearing & equilibrium (sensory only)
  5. parasympathetic to thorax & abdomen; pharynx, larynx
  6. tongue movement
  7. skin area supplied by one spinal nerve
  8. voluntary; one motor neuron to skeletal muscle; ACh; always excitatory
  9. thoracolumbar (T1-L2) lateral horn
  10. acetylcholine on nicotinic receptor
  11. modified ganglion; secretes epinephrine and NE into bloodstream
  12. long; synapses in or near target organ
  13. acetylcholine on muscarinic
  14. most organs get both branches with opposing effects
  15. symp dilates, parasymp constricts

Define it: high-yield vocabulary

Write a clear definition in your own words for each term.

  1. Cranial nerves
  2. Spinal nerves
  3. Dermatome
  4. Somatic nervous system
  5. Autonomic nervous system
  6. Sympathetic division
  7. Parasympathetic division
  8. Preganglionic neuron
  9. Postganglionic neuron
  10. Dual innervation
  11. Vagus nerve

Part 2 of 4 · Anatomy lab

Draw and label

Box A. The reflex arc (5 components)

Directions

  1. Use the patellar (knee-jerk) reflex as your example. Draw a leg with the patellar tendon being tapped by a reflex hammer.
  2. Component 1: Receptor. Draw a muscle spindle in the quadriceps. Label.
  3. Component 2: Sensory (afferent) neuron. Draw an axon going from the muscle spindle up to the spinal cord, entering the dorsal horn.
  4. Component 3: Integration center. Inside the spinal cord, show a single synapse (this is a monosynaptic reflex). Label.
  5. Component 4: Motor (efferent) neuron. Draw an axon leaving the ventral horn and going back down to the quadriceps.
  6. Component 5: Effector. The quadriceps contracts, kicking the leg up. Label.
  7. Add arrows showing the direction of signal flow.
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Box B. Sympathetic vs parasympathetic outflow

Directions

  1. Draw a side view of the spinal column.
  2. Sympathetic (thoracolumbar): show preganglionic fibers leaving the spinal cord from T1 through L2. Draw the sympathetic chain ganglia running parallel to the cord. Show short preganglionic fibers ending in chain ganglia, then long postganglionic fibers traveling to target organs.
  3. Parasympathetic (craniosacral): show preganglionic fibers leaving from the brainstem (via cranial nerves III, VII, IX, and especially X, the vagus) AND from S2-S4 (sacral). Show long preganglionic fibers traveling to ganglia near or on the target organs, then very short postganglionic fibers.
  4. Label two target organs (e.g., heart, lungs, gut) and note opposing effects: sympathetic increases heart rate, parasympathetic decreases it.
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Structures to label

Label each on your drawing.

  1. Receptor (muscle spindle)
  2. Sensory neuron (afferent)
  3. Dorsal horn
  4. Integration center (spinal cord synapse)
  5. Motor neuron (efferent)
  6. Ventral horn
  7. Effector (skeletal muscle)
  8. Sympathetic chain ganglia
  9. Preganglionic fiber (sympathetic)
  10. Postganglionic fiber (sympathetic)
  11. Preganglionic fiber (parasympathetic)
  12. Postganglionic fiber (parasympathetic)
  13. Vagus nerve (CN X)

Part 3 of 4 · Physiology lab

Reason it through

A. Sympathetic vs parasympathetic comparison

Why are sympathetic effects more widespread (affecting many organs at once) while parasympathetic effects are more targeted? Justify using preganglionic fiber length and ganglion location.
Both divisions release acetylcholine at preganglionic synapses. At postganglionic targets, sympathetic typically releases norepinephrine and parasympathetic releases acetylcholine. Predict what beta-blocker drugs (which block norepinephrine receptors in the heart) do to heart rate, and why.

B. Synthesis

1. A person is startled by a loud noise. List 5 specific sympathetic effects they experience over the next 10 seconds. For each, identify the target organ and the response.
2. After eating a large meal, parasympathetic activity dominates. Predict at least 3 specific physiological changes in this state and explain how 'rest and digest' is the appropriate metabolic context.
3. A patient takes an anticholinergic medication for an overactive bladder. Predict the side effects this drug will produce across other organs that also respond to acetylcholine. Why are dry mouth, blurred vision, and constipation common with these drugs?

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