Bio 209 Ch 15

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Bio 209 Ch 15
2010-07-14 01:17:28
Autonomic Nervous System ANS

Autonomic Nervous System
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  1. Compare the sensory input, motor output, and neurotransmitters released by the somatic nervous system and the autonomic nervous system
    • Sensory Input
    • Somatic: (1) sensory neurons carry info from somatic sensory receptors and special sense organs to the CNS (2) sensations consciously perceived
    • Autonomic: (1) sensory neurons carry info mainly from interoceptors to CNS (2) interoceptors are sensory receptors located in BV, visceral organs, muscles, nervous system that respond to changes in internal environment (3) sensations not usually consciously perceived

    • Motor Output
    • Somatic: (1) motor neurons extend from spinal cord to skeletal muscle (2) stimulation ALWAYS excitatory (3) conscious, voluntary control of contraction
    • Autonomic: (1) two motor neurons in series (2) first motor neuron extends from spinal cord and synapses à second motor neuron in autonomic ganglia; second motor neuron innervates effectors (3) effects of ANS are cardiac & smooth muscles, glands (4) stimulation is either excitatory of inhibitory (5) stimulation modifies contraction but may not initiate it

    • Neurotransmitters
    • Somatic: neurotransmitter is ALWAYS Acetylcholine (Ach)
    • Autonomic: neurotransmitter is EITHER Ach or Norepinephrine (NE)
  2. Name the two divisions of the ANS
    Sympathetic & Parasympathetic
  3. Define dual innervation
    one division stimulates organ activity while the other inhibits it
  4. Compare preganglionic and postganglionic neurons
    • Preganglionic:
    • (1) First neuron in motor pathway (2) Cell body in brain/spinal cord (3) Axon exits CNS as cranial/spinal nerve

    • Postganglionic:
    • (1) Second neuron in motor pathway (2) Cell body in autonomic ganglia (3) Axon extends to effector
  5. Compare the locations of the preganglionic neuron cell bodies of the sympathetic and parasympathetic divisions of the ANS
    Sympathetic: also called “Thoracolumbar” division because its cell bodies are located in lateral horns of the 12 thoracic, first two lumbar segments of spinal cord

    Parasympathetic: also called “Craniosacral” division because its cell bodies are located in nuclei of 4 cranial nerves in brainstem, in lateral gray matter of 2nd-4th sacral segments of spinal cord
  6. Describe the location of the sympathetic and parasympathetic ganglia
    Sympathetic: vertical row of ganglion on either side of vertebral column

    Parasympathetic: close to or within the wall of the effector
  7. Compare the length of pre- and post-ganglionic axons in the sympathetic and parasympathetic divisions
    Sympathetic Pre-Ganglionic Axons travel a short distance to ganglia near vertebral column, while Parapsympathetic Pre-Ganglionic Axons travel a longer distance to ganglia near their effectors
  8. Describe the contents of autonomic plexuses
    Location: thorax, abdomen, pelvis

    Contains axons of sympathetic and parasympathetic neurons
  9. Describe pathway of sympathetic preganglionic and postganglionic neurons from spinal cord to effectors
    • Pre-Ganglionic
    • Sympathetic: leaves spinal cord thru anterior (ventral) roots, then travel to nearest sympathetic trunk ganglion

    • Post-Ganglionic
    • Sympathetic: leaves trunk to (1) enter spinal nerves, to neck, trunk and limbs (2) form cephalic periarterial nerves (travel to hear by follwing arteries traveling form neck to hear) (3) form sympathetic nerves that innervate heart and lungs
  10. Describe pathway of parasympathetic preganglionic and postganglionic neurons from spinal cord to effectors
    • Pre-Ganglionic
    • Parasympathetic: leaves CNS as part of (1) a cranial nerve or (2) an anterior root of a spinal nerve

    • Post-Ganglionic
    • Parasympathetic:
  11. Name the neurotransmitter released by cholinergic neurons and the type of receptors that the neurotransmitter binds

    • Binds to:
    • - Nicotinic receptors because nicotine mimics Ach; DOES NOT mimic muscarinic receptors
    • - Muscarinic receptors because these receptors mimic Ach; DOES NOT mimic nicotine receptors
  12. Name the neurotransmitter released by adrenergic neurons and the type of receptors that the neurotransmitter binds

    • Binds to:
    • - Alpha Receptors: Alpha 1 & Alpha 2
    • - Beat Receptors: Beat 1, Beta 2, Beta 3
    • - Alpha1 & Beta 1 = Excitatory
    • - Alpha 2 & Beta 2 = Inhibitory
  13. Define agonists and describe the effects of phenylephrine
    • Agonist: chemical that binds to and activates a receptor, mimicking the effect of aneurotransmitter/hormone
    • - Phenylephrine: common ingredient of cold/sinus medicine that binds to adrenergic Alpha-1 receptors and mimics action of norepinephrine (constricts BV in nasal mucosa causing the production of mucus to decrease and relieving nasal decongestion
  14. Define antagonist. Describe the effects of propanolol (Inderal), and Metoprolol (Lopressor) on the ANS
    • Antagonist: chemical that binds to and blocks a receptor, preventing a neurotransmitter/hormone from exerting an effect
    • - Propanolol: antihypertensive drug that blocks Beta receptors and
    • prevents binding of norepinephrine/epinephrine to Beta receptors (decreases BP by blocking Beta-1 receptors in the heart, causing a decrease in HR and force of contraction)
    • - Metoprolol: selective Beta-1 blocker, binding only to Beta-1 receptors so it can reduce high BP without causing bronchoconstriction
  15. Describe anatomic tone
    Balance between sympathetic and parasympathetic activity (if sympathetic increases, parasympathetic decreases)
  16. Describe sympathetic and parasympathetic responses
    • Sympathetic:
    • (1) Fight-or-Flight
    • (2) Active when body is stressed (ex: running from a bear)

    • Parasympathetic:
    • (1) Resting and Digesting
    • (2) Active when relaxing after a meal, reading etc.
    • (3) SLUDD (Salivation, Lacrimation, Urination, Digestiong, Defecation)
  17. Describe an autonomic reflex arc and state what they control
    • Components:
    • (1) Receptor, sensory neuron, intergrating center, motor neuron, effector
    • (2) Main integrating centers in hypothalamus and brain stem; integrating centers for urination and defecation

    • Control:
    • (1) BP, respiration, digestion, defecation, urination
  18. Describe the role that the hypothalamus plays in control of ANS
    • (1) Receives sensory input from interoceptores
    • (2) Integrates info
    • (3) Sends output to autonomic centers in brain stem and spinal cord