A&P Chapter 14 Flashcards
The automatic nervous system consists of motor neurons that do what?
- Innervate smooth muscles, cardiac muscle, and glands
- Make adjustments to ensure optimal support for body activities
- Operate by subconscious control
What are examples of the ANS making adjustments to ensure optimal support for body activities?
Shunts blood to areas that need it, adjusts heart rate, blood pressure, and digestive processes
What are the neurotransmitter effects of the somatic nervous system?
All somatic motor neurons release acetylcholine. The effect is always stimulatory
What are the neurotransmitter effects of the ANS?
-Preganglionic fibers release ACh
-Postganglionic fibers release norepinephrine or ACh at effectors
-Effect is either stimulatory or inhibitory, depending on the type of receptors
What are the two divisions of the ANS?
Parasympathetic and Sympathetic
What does the parasympathetic division do?
Maintenance functions, conserves energy
What does the sympathetic division do?
Mobilizes body during activity
What is dual innervation?
All visceral organs are served by both divisions, but these divisions cause opposite effects
_____ ______ between these two divisions maintains homeostasis
Dynamic antagonism
What does the parasympathetic division do? (More in depth)
Keeps body energy use as low as possible, even while carrying out maintenance activities. Directs digestion, diuresis, and defecation
What is the parasympathetic division referred to as?
Rest-and-digest system
What is an example of what occurs with the parasympathetic system when a person is relaxing and reading after a meal?
- Blood pressure, heart rate, and respiratory rates are low
- Gastrointestinal tract activity is high
- Pupils are constricted, lenses accommodated for close vision
The sympathetic division is referred to as what?
Fight-or-flight system
What actions activates the sympathetic division?
Exercise, excitement, emergency, and embarrassment
What are examples of the symptoms caused by the sympathetic division?
Increased heart rate, dry mouth, cold & sweaty skin, dilated pupils
What is an example of what occurs with the sympathetic system during vigorous physical activity?
- Shunts blood to skeletal muscles and heart
- Dilates bronchioles
- Causes liver to release glucose
The sympathetic system is more ______ and _______ more organs than the parasympathetic system
More complex and innervates more organs
Some structures are innervated only by the sympathetic system, what are they?
Sweat glands, arrector pili muscle of the hair follicles, smooth muscles of all blood vessels
Most visceral organs have ____ _____, that are sometimes _____
Dual innervation; cooperative
Action potentials continually fire down the axons of both divisions, producing a dynamic antagonistic interaction. It works precisely to control visceral activity. What is an example of this in each of the two systems?
Sympathetic division increases heart and respiratory rates while inhibiting digestion and elimination
Parasympathetic division decreases heart and respiratory while allowing for digestion and discarding of wastes
Almost all blood vessel smooth muscle is entirely innervated by _______ ______ ______, so this division controls blood pressure, even at rest
Sympathetic fibers only
The sympathetic division can ______ these effects during times of stress
Override
Drugs that _____ parasympathetic responses increase heart rate and causes fecal and urinary retention
Block
What are the parasympathetic effects of the eye/iris?
Stimulates sphincter pupillae muscles; constricts pupils
What are the sympathetic effects of the eye/iris?
Stimulates dilator pupillae muscles, dilates pupils
What are the parasympathetic effects of the sweat glands?
No effect (no innervation)
What are the sympathetic effects of the sweat glands?
Stimulates copious sweating (cholinergic fibers)
What are the parasympathetic effects of the heart muscle?
Decreases rate (slows heart)
What are the sympathetic effects of the heart muscle?
Increases rate and force of heartbeat
What are the parasympathetic effects of the lungs?
Constricts bronchioles
What are the sympathetic effects of the lungs?
Dilates bronchioles
The sympathetic effects of the lungs are mediated by what?
Epinephrine release into the bloodstream from the adrenal medulla
What are the parasympathetic effects of the digestive tract organs?
Increases motility (peristalsis) and amount of secretion by digestive organs; relaxes sphincters to allow foodstuffs to move through tract
What are the sympathetic effects of the digestive tract organs?
Decreases activity of glands and muscles of the digestive system, constricts sphincters (like the anal sphincter)
What are the parasympathetic effects of the blood vessels?
Little to no effect (except blood vessels to the external genitalia)
What are the sympathetic effects of the blood vessels?
Constricts most vessels and increases blood pressure; constricts vessels of abdominal viscera and skin to divert blood to muscles, brain, and heart when necessary; epinephrine weakly dilates vessels of skeletal muscles during exercise
The sympathetic effects of the blood vessels are mediated by what?
Epinephrine release into the blood stream from the adrenal medulla
Many ANS disorders involve what?
Deficient control of smooth muscle activity
What is hypertension caused by?
Overactive sympathetic vasoconstrictor response to stress
What happens to the heart and artery walls in hypertension?
Heart must work harder, and artery walls are subject to increased wear and tear
How is hypertension treated?
With adrenergic receptor-blocking drugs
What is Raynaud’s syndrome?
Sudden constriction of small arteries of digits, results in loss of normal hue of distal skin. It’s accompanied by pain. Triggered by cold or emotional stress. Due to exaggerated local sympathetic response. More common in women.
