Chapter 11 Flashcards
Do both divisions of the autonomic nervous system innervate most effector organs?
yes
Primary function of the autonomic system
regulate organs to maintain homeostasis
Parasympathetic and sympathetic activities tend to be?
antagonistic
Parasympathetic nervous system
rest
Sympathetic nervous system
fight-or-flight response
What are the two types of neurons from CNS to effector organs
Preganglionic neurons
Postganglionic neurons
What do Autonomic ganglia do?
- Communication from preganglionic to postganglionic neuron
- Intrinsic neurons
What makes up the autonomic nervous system?
- Effector organs
- Cardiac muscle
- Smooth muscle
- Glands
- Adipose tissue
What nerves are apart of the parasympathetic ns?
cranial nerves
spinal nerves
pelvic nerves
Name the cranial nerves
- Cranial nerve X = vagus nerve
- Cranial nerve III = oculomotor
- Cranial nerve VII = facial nerve (drooll)
- Cranial nerve IX = glossopharyngeal nerve (throat glands)
Are pelvic nerves distinct from somatic spinal nerves?
yes
Efferent fibers belong to what type of nervous system?
Autonomic nervous system
Function of afferent nerve fibers
- Transmit information from visceral receptors to CNS
- Important in maintaining homeostasis
What are the two autonomic receptors?
Cholinergic and Adrenergic
Cholinergic receptors
more common; bind acetylcholine (symp and para)
Adrenergic receptors
bind norepinephrine (sympathetic)
Types of cholinergic receptors
- Nicotinic cholinergic receptors (ionotropic)
- Muscarinic cholinergic receptors (metabotropic)
Nicotinic cholinergic receptors
- Cause cation channels to open
- Channel opening results in depolarization
- Chromaffin (adrenal glands)- releases adrenaline
Muscarinic cholinergic receptors
- G protein coupled
- Effect depends on target cell
- parasympathetic, on the heart and smooth muscle
Two main classes of adrenergic receptors
- alpha and beta, and are both coupled to G proteins
Properties of alpha-adrenergic receptors
- Located in effector organs of sympathetic nervous system
- excitatory (muscle contraction and gland secretion)
- Affinity greater for norepinephrine
Properties of Beta-adrenergic receptors
- All activate cAMP
- Affinities for norepinephrine and epinephrine vary
- Inhibitory
Most common adrenergic receptor
alpha
Properties of Beta 1 adrenergic receptors
- Located in cardiac muscle and kidneys
- Usually excitatory
- Equal affinity for norepinephrine and epinephrine
Properties of beta 2 adrenergic receptors
- Located in some blood vessels and smooth muscle
- Usually inhibitory
- Greater affinity for epinephrine than norepinephrine
Whats bw efferent and effector organ in the autonomic nervous system?
synapses
Neuroeffector junctions
Between postganglionic neuron and effector organ
Varicosities
Neurotransmitter produced and stored in axon swellings
Varicosities are released in response to what?
action potential in postganglionic neuron
Name the 6 steps of the neuroeffector junctions
- 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 occurs
- Neurotransmitter is degraded and diffuses away; reuptake occurs
Increases in parasympathetic activity are coupled with?
decreases in sympathetic activity
Increases in sympathetic activity are coupled with
decreases in parasympathetic activity
Parasympathetic activity
- Quiet, relaxed states
- Active in “rest and digest”
- Increases gastrointestinal activities
- Decreases heart rate and blood pressure
Sympathetic activity
- Prepares for emergency, stress, and exercise
- Increases heart rate and blood pressure
- Mobilizes energy stores
- Dilates pupils
- Decreases gastrointestinal and urinary functions
Are both parasympathetic and sympathetic active ?
yes, When at rest parasympathetic nervous system dominates
Somatic Nervous System
Voluntary
- Motor neurons (efferent)
- Innervate skeletal muscle
Somatic NS neurotransmitter
acetylcholine
What receptors are in skeletal muscle?
nicotinic cholinergic
One motor neuron innervates?
many muscle fibers
Each muscle fiber is innervated by ?
only one motor neuron
Terminal bouton
axon terminal
- neuromuscular junction
Motor end plate
specialized muscle membrane at junction, infoldings are many nicotinic receptors
All motor neurons release ?
acetylcholine
- Acetylcholinesterase
Synapses are ?
excitatory
Action potential in motor neuron triggers release of ?
acetylcholine at neuromuscular junction
End-plate potential occurs at?
motor end plate
Neuromuscular junctions are always?
excitatory
What are the 8 steps of communication at the neuromuscular junction?
- Action potential arrives at terminal bouton
- Voltage-gated calcium channels open
- Calcium enters cell, triggering release of ACh
- ACh diffuses across cleft and binds to nicotinic receptors on motor end plate
- ACh triggers opening of channels for the 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
Look at figure 11.15
Look over table 11.4
