Chapter 15 - autonomic nervous system Flashcards
what does the ANS respond to?
subconscious visceral sensations
what are the components of the ANS?
autonomic sensory neurons, integrating centers in the CNS, and autonomic motor neurons
how does the ANS operate?
unconsciously
-Hypothalamus and brain stem regulate ANS reflexes
Sensory receptors called interoceptors located in blood vessels, visceral organs, muscles, and nervous system- monitor conditions in the internal environment
describe somatic motor neurons
- Myelinated neurons extends from CNS to muscle
- Always excites muscle
- Always release acetylcholine
what is a Ganglion
collection of cell bodies in PNS
describe autonomic motor neruons
- Two motor neurons in series (pre- and post-ganglionic)
- Is unmyelinated
- Can excite or inhibit effector muscles
- Can release either Ach or nonepinephrine
what is dual ANS innervation
body organs receive impulses from both sympathetic and parasympathetic neutrons
-The nerve impulses from one division will stimulate an organ, while impulses from other division will decrease activity
pre-ganglionic cell bodies of the sympathetic NS are located where?
- motor neuron cell bodies of the sympathetic NS located in lateral horns of 12 thoracic segments and first 2 lumbar segments of the cord
- (thoracolumbar division)
pre-ganglionic cell bodies of the motor neuron in parasympathetic NS are located where?
nuclei of 4 cranial nerves 3, 7, 9, 10 and in lateral gray horn of the sacral area of spinal cord (S2-S4)
-(craniosacral division)
vagus nerve (CN X)
-carries nearly 80% of the total parasympathetic flow to the organs of the thorax and upper abdomen
what does the sacral output innervate?
Lower abdominal and pelvic organs
what are the sympathetic ganglia (2)?
1) Sympathetic trunk ganglia- along either side of spinal cord
- Innervate organs above the diaphragm
2) Prevertebral ganglia
- Anterior to the spinal cord
- Innervate below the diaphragm
what are the parasympathetic ganglia called?
terminal ganglia
describe terminal ganglia
- Located near the target organs
- Parasympathetic preganglionic neurons are long, post ganglionic neurons are short
where do post-ganglionic neurons of the sympathetic division terminante
in several different visceral organs
- widespread response
- Highly branched-many synapse with >20 post-synaptic neurons
- Presynaptic neurons synapse with 4 or 5 post-synaptic neurons, which supply a single visceral effector
what are the 4 differences between sympathetic and parasympathetic divisions
1) Location of pre-ganglionic cell bodies in the CNS
2) Location of ganglia
3) Number of pre-ganglionic branches
4) Length of pre- and post-ganglionic axons
what are the 2 main and 2 subtypes neurotransmitters used in the ANS
acetylcholine and norepinephrine
Nicotinic
Muscarinic
where is acetylcholine used in the nervous system? what is this called?
- used in all of the synapses of sympathetic and parasympathetic ganglia
- Synapses at which Ach is used= cholinergic
where are nicotinic receptors found?
in ganglia
where are muscarinic neurotransmitters found?
in synapses with the effector organs
what does adrenergic refer to?
Synapses at which norepinephrine or epinephrine are used.
two types = alpha (1&2) and beta (1,2,&3)
for alpha and beta neurotransmitters; explain the jobs for alpha 1 & 2 and beta 1-3
Alpha 1 and Beta 1 = excitation
Alpha 2 and Beta 2 = inhibition
Beta 3= brown adipose tissue
describe the differences between pre-ganglionic axons of the sympathetic and parasympathetic divisions
sympathetic - short
parasympathetic - long
describe the differences between ganglia of the sympathetic and parasympathetic divisions
sympathetic- sympathetic trunk pre-vertebral
parasympathetic - terminal
