Chapter 11 Flashcards
What is dual innervation ?
Both branches of ANS innervate most effector organs
Primary function of ANS
regulate organs to maintain homeostasis
What are the two neurons fron CNS to effector organs
Preganglionic neuron
Postganglionic neuron
Purpose of autonomic ganglia
communication from preganglionic to postganglionic neuron
What are intrinsic neurons?
modulate the flow of information to the target organs
What are the effector organs
Cardiac muscle
Smooth muscle
Glands
Adipose tissue
Where do preganglionic neurons originate?
Thoracolumbar spinal cord
Preganglionic exits via what
Ventral root of spinal cord and enters spinal nerve
Pathway for postganglionic
Leave ganglia as gray ramus and re-enter spinal nerve
Travel to effector organ in spinal nerve
Where do preganglionic neurons originate?
brainstem or sacral spinal cord
two primary receptors in the nervous system are what?
Acetylcholine and norepinephrine.
Acetylcoline what type of neurons
Preganglionic, parasympathetic postganglionic and sympathetic postganglionic
Hormones of the Adrenal Medulla and percentages
80% epinephrine and 20% norepinephrine, small amount of dopamine
Cholinergic means it releases what?
releases acytelcholine
Purpose of nicotinic cholinergic receptors?
Open channels for cations, results in depolarization. Excitatory effect on target cell
What is muscarinic cholinergic receptors?
Coupled to G protein, response triggered by binding of acyteylcholine depends on target cell
what class of cholinergic receptor found in autonomic postganglionic ? Effector organ for parasympathetic? Skeletal muscle?
Nicotinic, muscarinic, and nicotinic
Two main classes of adrenergic receptors.
Alpha and Beta. All coupled to G proteins
How many subclasses for alpha and beta
2 alpha 3 beta
Where are alpha adrenergic receptors located? Affinity is greater for what?
Effector organs of sympathetic nervous system, norepinephrine
What can be said about all Beta adrenergic receptors?
All activate cAMP
Where are Beta 1 Adre. Receptors located? Excitory or inhibitory? What about affinity for epinephrine and norep.
cardiac muscles and kidneys. Usually excitory, equal affinity.
Beta 2 located where? Inhibitory? Greater affinity for what?
some blood vessels and smooth muscle. Yes. Greater affinity for epinephrine.
beta 3 located where?
Adipose tissue. Excitory, equal affinity.
What is autonomic neuroeffector junctions?
Synapses between efferent and effector organ in ANS
Neurotransmitter stored where for Neuroeffector junction?
Axon swellings called varicosites. In response to action potential in postganglionic neuron.
Events at the neuroeffector junciton (6)
- 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 is increased and decreased during parasympathetic activity
Increase in gastrointestinal activities and decrease in heart rate and blood pressure
msot changes in ANS accomplished through what?
visceral reflexes(changes in the functions of organs that occur in response to changing conditions in the body
What do the hypothalamus, pons and medulla maintain?
Homeostasis
Waht do cerebral cortex and limbic system control
emotions
How many neurons between CNS and effector organ in SNS
one-motor neuron
what is the effector organ in SNS
Skeletal muscle
SNS originate from where?
Ventral Horn
What is the neurotransmitter for SNS
Acetylcholine
What are the receptors in skeletal muscle
Nicotinic cholinergic
What is a motor unit
Motor neuron and the muscle fibers it innervates
How many muscle fibers does a motor unit innervate
MAny
What is a neuromuscular junction
Synapse between a motor neuron and a muscle fiber
What are the two anatomical portions of the neuromuscular junction?
Terminal button= axon terminal and motor end plate= specialized muscle membrane at junction
All motor neurons release what?
Acetylcholine
What type of receptors are on skeletal muscle cells
nicotinic cholinergic
All synapses are what for neuromuscular junction
Excitatory
what degrades acetylcholine in synaptic cleft
Acetylcholinesterase
Activation of motor neuron depends on what
Summation os EPSPs and IPSPs
Action potential in motor neuron triggers what
release of acetylcholine at neuromuscular junciton
8 steps of cummunicaiton at the neuromuscular junciton
- Action potential arrives at terminal button.
- Voltage-gated calcium channels open.
- Calcium enter cell triggering release of ACh
- ACh diffuses accross cleft and binds to nicotinic receptors on motor end plate
- ACh triggers opening of channels for small cations sodium and potassium
- Net movement of positive charge in = depolarization
- EPP causes action potential in muscle cell
- Action potential spreads through muscle causing contraction
