Flashcards in ANS Ch 16 Deck (45):
System of motor neurons that innervates smooth and cardiac muscles and glands. Also called involuntary or visceral motor system.
Two neuron chain
ANS uses two neurons to reach the effector unlike the CNS that uses only one
First neuron whose body lies lies within the brain or spinal cord, it synapses with the second motor neuron.
Post ganglioninc neuron
Second motor neuron whose cell body is within the autonomic ganglion outside the CNS.
2 autonomic neurotransmitters
Epi and Nor Epi
Autonomic postganglionic fibers release?
Epi and Nor Epi
Secreted by most sympathetic fibers
Parasympathetic fibers release
Two divisions of the ANS--sympathetic and parasympathetic--balance each other out
Some organs only receive sympathetic stimulation but vital organs have both.
Rest and digest:
Craniosacral: originate in brain and sacrum
Long preganglion short post ganglion fibers
Ganglion are close to organ served
Fight or flight:
Thoracolumbar: originate in thoracic and lumbar
Short preganglion and long post ganglion fibers
Ganglion are close to spinal cord
Innervated the smooth muscles of the eye that causes the pupil to constrict and lens to bulge. Synapse in the ciliary ganglia
Activate nasal glands and lacrimal glands: pterygopalatine ganglia
Stimulate sublingual salivary glands: submandibular ganglia
Synapse in the otic ganglia. Activate parotid salivary glands anterior to the ears
Account for 75% or preganglionic parasympathetic fibers and innervate virtually every thoracic and abdominal oregan
Serves pelvic organs and distal half of the intestines. S1-S4 forn the pelvic splanchnic nerves.
Arise from T1 - L2,
3 locations of sympathetic ganglionic neurons
Sympathetic chain ganglia (paravertebral)
Collateral ganglia (prevertebral)
Adrenal medulla (release neurotransmitters into the blood stream)
Fibers that release ACh, effects are always excititory
Fibers that release NE,
ACh binding receptors
Affects are always stimulatory
Found on all postganglionid neurons both sympathetic and parasymathetic
Either inhibitory or stimulatory
NE Binding Receptors
NE and Epinephrine
Can be either excitatory or inhibitory
depending on target organ
Sympathetic or vosomotor tone
Partial continual blood vessal constriction, dilate slightly and constrict slightly to maintain BP
Slows heart rate and dictates normal activity in the digestive and urinary tracts
Uniquely sympathetic functions
Thermoregulatory responce to heat
Release of Renin from Kidneys
Metobolic rate regulation
Parasympatheitc only has localized affects
Localized and Diffuse affects
Parasympathetic is both
NE is not hydrolysed as fast as ACh
NE and Epinephrine are released into the boold streem by the Adrenal glands and have a longer lasting effect.
Brain stem and spinal cord controls
Most direct influence over ANS
Acting through the ANS it coordinated heart activity, BP, body temp, water ballance and endocrine activity. When there is an emotional sterss signal from limbic system the hypothalamas activates the ANS
Becoming aware of physiological conditions with the goal of continual influence
Have two neurons in motor componant
a 1 are the most common: stimulate G protein activation and cause a realease of intracellular calcium from ER
a2 results with lowering cyclic - AMP in the cytoplasm
Effects skeletal muscles, heart, lungs, and liver.
G protein activation increases the cyclic- AMP in the cytoplasm
B1: increases metabolic activity
B2: causes inhibition respiratory passageways dilate
3 collateral ganglia
Sympathetic Division Summary
2 sets of chain ganglia- on each side of spinal cord
3 collateral ganglia- one anterior and two to the adrenal medulla
Preganglionic fibers are short
Post ganglionic fibers are longer
All preganglionic neurons release Ach
Most post ganglionic neurons release NE but a few release Ach or NO.
Two types of parasympathetic ganglia
Terminal: located near the target tissue
Intramural: embedded in the target tissue
4 cranial ganglia of the parasympathetic
Summary of the Parasympathetic Division
Visceral motor nuclei associated with cranial nerves III, VII, IX and X and sacral segments S1-S4
Ganglia are located proximal or in the target organ
All parasympathetic neurons are cholinergic
Contain either Nicotinic receptors or Muscarinic receptors (excitement of inhibition)
Stimulation is breif and restricted to specific organs
6 autonomic plexus'
Background level of activity in which both sympathetic and parasympathetic divisions innervate. This provides a grater range of control options because of the opposing effects of the two systems. Small amounts of Ach and NE are released contimuously.
Visceral reflex arc
Consists of a receptor, a sensory neuron, a processing center (one or more interneurons) and two visceral motor neurons.
Long reflex: the processing step involves an interneuron within the CNS
Short reflex: Bypass the CNS - synapse in autonomic ganglia outside the spinal cord