24.3 Autonomic nervous system Flashcards
(67 cards)
What are visceral change the ANS can alter rapidly and intensly?
- HR can double in 3-5 seconds
- double arterial pressure
- initiate sweating
What is the best way to describe the pathways of the ANS?
2 series of neurons. preganglionic and postganglionic neurons
Describe the features of a preganglionic neuron.
- CNS contains the cell bodies
- myelinated axons
- Ach is the neurotransmitter
Whate are unique features of the postganglionic neurons?
- cell bodies locate in peripheral ganglia
- non-myelinatd
3.parasympathetics=Ach
sympathetics= norepinephrine
Where are large numbers of mitochondria generally found in the ANS pathways to organs?
in terminal fibers with enlarged varicosities
Where do preganglionic neurons of the sympathetic system lie?
- T1-L2 intermediolateral horn
2 synapse in paravertebral chain
What fibers form 8% of fibers in teh average nerve?
postganglionic sympathetic fibers
What kind of fibers are postganglionic sympathetic fibers?
type C fibers (unmyelinated) that control blood vessel, sweat glands and piloerector muscles
What nerve fibers pass through the gray rami?
postganglionic sympathetic fibers
What are the 12 thoracic ganglia pairs normally referred to?
stellate ganglion. with first pair fused with inferior cervical ganglion
What are the components of the cervical ganglia?
- superior
- middle
- inferior
What nerves supply the preganglionic sympathetic supply to the thoracic viscera?
T1-T5
What nerves supply the postganglionic sympathetics to the thoracic viscera?
- superior, middle, inferior cervical ganglion
2. T1-T5 paravertebral ganglia
What is the function of the cardiopulmonary splanchnic nerves that travel all by themselves?
- dilate coronary artery
- increase heart rate
- bronchodilation
What comprise splanchnic nerves?
preganglionic fibers and visceral sensory fibers
What do splanchnic nerves supply?
abdominal viscera
Where do splanchnic nerves synapse?
prevertebral ganglia
What nerves form the greater splanchnic nerves?
- T5-T9
2. synapse in the celiac region
What nerves form the middle splanchnic nerves?
T10-T11, synapse in superior mesenteric ganglion
What nerves form the least splanchnic nerves?
T12, synapse in the aorticorenal ganglion
The adrenal medulla releases 80% epinephrine and 20% norepinephrine via the______________system.
sympathetic
Effects of circulating norepinephrine?
- blood vessel constriction
- increase HR
- inhibit GI
- dilate pupils
What are the secretory cells of teh adrenal medulla?
innervated by postganglionic neurons with rudimentary fibers that secrete epinephrine and norepinephrine
Which hormone is more effective in elevating arterial pressure?
norepinephrine