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List the two categories of the Autonomic Nervous System.
What is the primary function of the ANS?
Regulate organs to maintain homeostasis.
Describe the general anatomy of the ANS?
- Preganglionic Neurons
- Postganglionic Neurons
List the neurotransmitters released from the following neurons:
Parasympathetic Postganglionic Neurons
Sympathetic Postganglionic Neurons
Where do preganglionic neurons originate?
In the thoracolumbar spinal cord
Describe the general structure and linkage of neurons in the sympathetic nervous system.
- Short preganglionic neurons to sympathetic chain.
- Long Postganglionic neurons from chain to effector organs.
- Ganglia linked together in sympathetic chain.
Describe the sympathetic pathway to and from the sympathetic chain.
- Preganglionic neurons exit the ventral root of the spinal cord and enters the spinal nerve. Axons leave the spinal nerve as white ramus and enter the sympathetic ganglia. Ten they communicate with the postganglionic neurons.
- Postganglionic neurons leave the ganglia as gray ramus and re-enter the spinal nerve. they then travel to effector organ in the spinal nerve.
Describe general parasympathetic nervous system pathways and anatomy.
- Preganglionic neurons originate in brainstem or sacral spinal cord. These long preganglionic neurons extend to ganglia near the effector organ where it synapses with the postganglionic neuron.
- Short postganglionic neurons from ganglia to effector organs.
List the cranial nerves of the parasympathetic nerves.
- Oculomotor Nerve (3)
- Facial Nerve (7)
- Glossopharyngeal Nerve (9)
- Vagus Nerve (10)
What spinal nerves are part of the parasympathetic nervous system?
List and describe the two types of cholinergic receptors.
- Nicotinic cholinergic receptors : Open channels for cations (NA & K), depolarization
- Muscarinic Cholinergic Receptors : G protein coupled, effect depends on target cell.
List and describe the locations of cholinergic receptors.
- Autonomic postganglionic : Nicotinic cholinergic
- Effector organ for parasymathetic : Muscarinic cholinergic
- Skeletal muscle : Nicotinic cholinergic
Are all adrenergic receptors coupled to G proteins?
Describe the affinity of each type Adrenergic Receptor.
- A1 : Greater for Norepinephrine than epinephrine
- A2 : Greater for Norepinephrine than epinephrine
- B1 : Equal for Norepinephrine and epinephrine
- B2 : Greater for epinephrine than Norepinephrine
- B3 : Equal for Norepinephrine and epinephrine
Describe the location of each type of Adrenergic Receptor.
- A1 : Most vascular smooth muscle, pupils
- A2 : Some vascular smooth muscle, adipose tissue
- B1 : Cardiac muscle, Kidneys
- B2 : Some blood vessels, smooth muscles
- B3 : Adipose tissue
Describe the normal responce envoked by the stimulation of each type of adrenergic.
- A1 : Usually Excitatory
- A2 : Usually Excitatory
- B1 : Usually Excitatory
- B2 : Usually Inhibitory
- B3 : Usually Excitatory
All Beta Adrenergic Receptors activate what?
What is the autonomic neuroeffector junction?
A synapse between efferent and effector organ in the autonomic nervous system.
Describe the events that occur at a Neuroeffector Junction.
- Action potential arrives at varicosity.
- Voltage-gated Ca2+ channels open.
- Ca2+ triggers exocytosis of neurotransmitter.
- Neurotransmitter binds with receptors on effector organ.
- Response in effector organ.
- Neurotransmitter degraded, diffuses away, reuptake
What enzyme degrades Acetylcholine?
What enzyme degrades Norepinephrine?
What type of neuron links the CNS to the effector organs?
What is a motor unit?
Motor neuron and the muscle fibers it innervates.
Describe the neuromuscular junction?
- Synapse between a motor neuron and a muscle fiber.
- Terminal buuton : Axon Terminal
- Motor end plate : specialized muscle membrane at junction.
- All motor neurons release acetylcholine.
- Skeletal muscle receptors are nicotinic cholinergic receptors.
- All synapses are excitatory.
What is EPP ( End plate potential)?
Action potential of motor neuron triggers release of acetylcholine at neuromuscular junction.
Describe the communication at the neuromuscular junction.
- Action potential arrives at terminal bouton.
- Voltage-gated calcium channels open.
- Calcium enters the cell triggering ACh release.
- ACh diffuses across cleft and binds to nicotinic receptors on motor end plate.
- ACh triggers opening of channels for small cations (Na and K)
- Depolaration occurs (EEP)
- An action potential is generated.
- Action potential spreads through muscle causing contraction.
Describe Myasthenia gravis.
- EPPs are smaller than normal.
- Autoimmune disease.
- Rapid and serve fatigue following use of certain muscle group.
Describe the toxin of a black widow spider?
- Stimulates the release of acetylcholine at NMJ.
- Muscle spasms and rigidity.
Describe the toxin of a rattlesnake.
- Inhibits the release of acetylcholine.
- Flaccid paralysis.
What is Curare?
A paralyzing toxin that binds to acetylcholine binding sites preventing ACh from acting.