Bio 224 Theme 9

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  1. The main nerves of
    the parasympathetic
    NS are the __
    tenth cranial nerves: the vagus nerves
  2. the vagus nerves
    • – Originate in the medulla oblongata
    • -the tenth cranial nerve
    • -Called the wondering nerve because it is composed of mostly sensory neurons
    • -communicates the state of the viscera to the brain.
    • -attached to most organs (not kidney or spleen)
  3. Where do Parasympathetic neurons extend out from the spine?
    At the brain and down at the lower tip
  4. Functions of the parasympathetic nervous system
    • • Returns the body functions to normal after they have been altered by sympathetic stimulation
    • – Slow down of the heartbeat
    • – Lower blood pressure
    • – Constrict the pupils
    • – Increase blood flow to the skin and viscera
    • – Cause peristalsis of the GI tract
    • • A useful acronym to summarize the
    • functions of the parasympathetic nervous system:
    • – Salivation, Lacrimation(crying), Urination,
    • Digestion and Defecation and Sexual arousal
  6. Acetylcholine (ACh)
    -chemical makeup
    -Which nervous system does it act in?
    • • A polyatomic cation, ester of acetic acid and choline;
    • • One of most widespread neurotransmitters;
    • – Acts as a neurotransmitter in both the peripheral nervous
    • system (PNS) and central nervous system (CNS);
  7. Acetylcholine (ACh) is the principal neurotransmitter in all ___ ganglia
  8. Acetylcholine
    -Uses in the motor division of the somatic nervous system
    -neuromuscular junctions
    -cardiac tissue
    • • The only neurotransmitter in the motor division of the
    • somatic nervous system;
    • – At neuromuscular junctions in skeletal muscle has an
    • excitatory effect;
    • – In cardiac tissue has inhibitory effects - lowers heart rate.
  9. ACh has two types of effects:
    -what makes the distinction?
    • nicotinic
    • muscarinic
    • -Response of postsynaptic cell depends on receptor type
  10. nicotinic
    On the postsynaptic side of the neuromuscular junction the skeletal voluntary muscles, which it is not considered to be part of PNS.
  11. muscarinic
    • On the postganglionic, parasympathetic effect on the exocrine glands and on smooth and cardiac muscles
  12. Nicotinic ionotropic receptors
    (2)Site of receptor:
    (3)respond to Acetylcholine release from:
    (1)ligand-gated ion channels

    • (2)-All autonomic ganglia
    • -Motor end plates of skeletal muscle fibers
    • -Some CNS cell bodies and dendrites

    • (3)-Sympathetic and Parasympathetic preganglionic fibers
    • -Motor neurons
    • -Some CNS presynaptic terminals
  13. Muscarinic metabotropic receptors
    (2)Site of receptor:
    (3)respond to Acetylcholine release from:
    (1)G-protein coupled receptors (GPCRs)

    • (2)Effector cells(cardiac muscle, smooth muscle, glands)
    • - some CNS cell bodies and dendrites

    • (3)-Parasympathetic postganglionic fibers
    • -some CNS presynaptic terminals
  14. Two main types of Nicotinic receptors
    -selectively blocked by what?
    muscle type: selectively blocked by curare

    neuronal type:selectively blocked by hexamethonium
  15. How do ionotropic and metabotropic receptors compare?
    • ionotropic has a channel that allows ions such as Na+, K+, or Cl- to flow.
    • -activated quickly but only open for miliseconds, used for quick response

    • metabotropic is a seven transmembrane receptor that triggers a series of intracellular events that results in:
    • -Opening of Na+, K+ and Ca++ channels;
    • -Activation of intracellular signals
    • -takes longer to open channels, not involved in quick responses
    • -activated from seconds to minutes, longer lastic effect than ionotropic

    -Both encourage flow of Na+ and K+
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Bio 224 Theme 9
2013-10-10 22:25:55
Bio 224 Theme

Bio 224 Theme 9
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