Chapter 14 Autonomic Nervous System
The Sympathetic Nervous System increases what five things?
1. heart rate 2. blood pressure 3. blood glucose levels 4. sweating 5. respiratory rates, (bronchioles dilate)
Explain what is meant by "carry both fibers"?
1. spinal and some cranial nerves carry both somatic and autonomic nerve fibers
Give an example of "carrying both fibers."
Example: a. oculomotor nerve (III) includes autonomic nerves (parasympathetic) that innervate smooth muscles of eye for pupil constriction & lens focusing - oculomotor nerve (III) also includes somatic motor nerve fibers to four extrinsic eye muscles that help move the eyeball (e.g. inferior oblique and medial, superior, and inferior rectus muscles)
Which of the two neurons is longer in the sympathetic division?
Postganglionic Neuron
(Parasympathetic Nervous System-craniosacral division) How do pre- and postganglionic fibers differ?
Preganglionic fibers are long fibers Postganglionic fibers are short fibers
(Uniquely Sympathetic Functions) stimulates...
arrector pili muscles (erects hair follicles)
Which drug inhibits parasympathetic secretions so eyes can be kept dilated?
atropine (anti-Ach)
(Sympathetic Response) How do the superficial vessels change?
selective superficial *vasoconstriction* during exercise allows vessels of heart & muscles to dilate
(Sympathetic Response) How do the vessels of the heart and muscles change?
selective superficial vasoconstriction during exercise allows *vessels of heart & muscles to dilate*
Describe the general effect of ACh
short lived, local, stimulatory effect
(Uniquely Sympathetic Functions) skeletal muscle
skeletal muscle - stronger, quicker contractions
What type of effectors does the Autonomic Nervous System's motor fibers innervate?
smooth muscles, cardiac muscles, and glands (called effectors because they have effects!)
(Uniquely Sympathetic Functions) cells
cells - enhanced metabolic rate
Raynaud's disease
condition that causes some areas of body (fingers, toes, tip of nose & ears) to feel numb & cool in response to cold temperatures or stress. - disorder caused by narrowing of blood vessels that supply blood to skin, limiting circulation
Pathway to Effectors
consists of two neurons in chain: 1. preganglionic nerve fiber 2. postganglionic nerve fiber
How does the Parasympathetic Nervous System affect the pupil?
constricts pupils
Most visceral organs are innervated by both...
sympathetic and parasympathetic systems, but...
(Parasympathetic Nervous System-craniosacral division) Where do postganglionic fibers synapse?
synapse at ganglia near or within visceral effector organs
Hirschsprung's disease
functional blockage of large intestine caused by failure of parasympathetic innervation
(Parasympathetic Functions) calms the...
heart
The Sympathetic response shunts blood away from skin and GI tract (digestive viscera) to...
heart, brain & skeletal muscles
Hypertension
high blood pressure (equal to or greater than 140 over 90 mmHg)
(Sympathetic Response) What is the effect of the hormone renin?
hormone renin released by kidneys increases blood pressure & metabolism
meditation and biofeedback
indirect but conscious control of ANS -based on control of "feelings" that influence visceral control, (e.g. calmness slows heart rate)
(Uniquely Sympathetic Functions) most blood vessels...
innervated by sympathetic fibers; - causes vasomotor tone & vasoconstriction higher blood pressure - shunts blood away from skin & viscera toward muscles, heart, & brain
(Uniquely Sympathetic Functions) kidney response
kidney response to sympathetic stimulus: 1. vasoconstriction - reduces urine output 2. increases renin secretion higher bp & fluid retention
(Uniquely Sympathetic Functions) liver
liver -increased blood glucose release
Describe the general effect of adrenergic neurotransmitter: norepinephrine (NE)
longer acting, more widespread effects, stimulatory
Function of Autonomic Nervous System
maintenance of homeostasis
ANS neurons are incorporated into which nerves?
many neurons of the ANS are incorporated into *spinal or cranial nerves* for most of their course
Give an example of "indirect control" of the ANS
meditation and biofeedback
What does muscarine mimic?
mimics parasympathetic response - exites salivary, tear & sweat glands; inhibits cardiac muscle
What does nicotine: mimic?
mimics sympathetic response -increased metabolic rate; causes epinephrine release from adrenal gland
(Differences Between Somatic & Autonomic Function) myelination
missing in postganglionic autonomic axons
adrenergic neurotransmitter: norepinephrine (NE) released by...
most sympathetic postganglionic fibers
(Parasympathetic Nervous System) Increased digestive and urinary tract...
motility of smooth muscle; motility of GI & Urinary tracts lead to elimination of wastes (both feces & urine)
(Cholinergic (ACh) receptors) Which receptor may inhibit cardiac tissue while stimulating GI motility?
muscarinic receptors: found on all postganglionic cholinergic effectors; mixed effects: inhibits heart, but increases GI tract motility
Which drugs prevent ACh breakdown?
neostigmine (anti-AChase)
(Cholinergic (ACh) receptors) Which receptor is always excitatory?
nicotinic receptors: found on skeletal muscle (neuromuscular junction), ganglionic neurons, & the adrenal medulla - always excites (opens channels; allows for depolarization)
(Differences Between Somatic & Autonomic Function) neurotransmitters
norepinephrine (instead of Ach) is released by postganglionic sympathetic fibers
Adrenergic (NE) receptors - receive...
norepinephrine or epinephrine (noradrenalin or adrenalin)
(2nd Neuron) postganglionic nerve fiber
postganglionic neuron cell body is found within a ganglion of the PNS
(Sympathetic Nervous System-thoracolumbar division) How do pre- and postganglionic fibers differ?
preganglionic fibers are short fibers postganglionic fibers are long fibers
Which neuron is longer in the parasympathetic division?
preganglionic neuron
(1st Neuron) preganglionic nerve fiber
preganglionic neuron cell body is found within CNS
neostigmine (anti-AChase)
prevents breakdown of ACh, used to treat myasthenia gravis (disease where antibodies block, alter, or destroy receptors for Ach)
tricyclic antidepressants (elavil)
prolongs activity of norepinephrine
The Sympathetic Nervous System dilates...
pupils
Cholinergic (ACh) receptors
receive ACh (acetylcholine) Includes: a. nicotinic receptors: found on skeletal muscle (neuromuscular junction), ganglionic neurons, & the adrenal medulla - always excites (opens channels; allows for depolarization) b. muscarinic receptors: found on all postganglionic cholinergic effectors; mixed effects: inhibits heart, but increases GI tract motility
Neuroreceptors
receive neurotransmitters; - attachment sites for neurotransmitters on postsynaptic membrane; Include 2 types: Cholinergic (ACh) receptors and Adrenergic (NE) receptors
beta blockers
reduce heart rate and prevent arrhythmias (since this blocks the beta cardiac receptors, which stimulate heart contractions)
Interaction of Sympathetic and Parasympathetic Systems Ex: Reproductive Activities (external genitalia)
a. parasympathetic control: erection (penis or clitoris ("point") b. sympathetic for: ejaculation or vaginal peristalsis ("shoot")
cholinergic neurotransmitter: acetylcholine (ACh) released by...
a. released by all preganglionic fibers b. released by all parasympathetic postganglionic fibers
(Uniquely Sympathetic Functions) adipose tissue
adipose tissue - fat mobilized for fuel (lipolysis)
(Uniquely Sympathetic Functions) causes release of...
adrenal medulla secretions (epinephrine & norepinephrine)
What types of adrenergic receptors stimulate?
alpha 1 and 2: stimulates - causes contraction
Sympathetic Nervous System
"fight or flight", emergency conditions
Parasympathetic Nervous System
"rest and digest" 1. conserves body energy & maintains basal level of metabolism 2. constricts pupils 3. increases digestive and urinary tract motility of smooth muscle; motility of GI & Urinary tracts lead to elimination of wastes (both feces & urine)
(Parasympathetic Functions) stimulates muscles of...
(Parasympathetic Functions) GI tract
Autonomic Nervous System
(Part of the Motor Division of the PNS) Made up of the Sympathetic Division and the Parasympathetic Division
(Parasympathetic Functions) stimulates ciliary muscles of...
*eye* - lens bulges for close focus
How do neuroreceptors differ from neurotransmitters?
?
Which fiber does not release ACh? Where?
?
What does the CNS control?
CNS (especially cerebral cortex, spinal cord, brain stem, & hypothalamus) controls reflex activity at subconscious level
How does the cerebral cortex influence the ANS?
Cerebral Cortex: may modify ANS through connections with limbic system; (e.g. a "scare" makes the heart race)
How does the efficiency of the ANS change over one's lifetime?
Efficiency of ANS declines in older adults Evidence: 1. decreased glandular secretions 2. decreased gastrointestinal motility 3. slowed sympathetic vasomotor responses to changes in position
What is the "boss" of the ANS and coordinates the ANS?
Hypothalamus: "boss" coordinates the ANS; controls somatic and endocrine responses
(Sympathetic Nervous System-thoracolumbar division) Where do postganglionic fibers synapse?
Synapse at ganglia near the *spinal cord*; -paravertebral chain ganglion: location of synapses
(Sympathetic Nervous System-thoracolumbar division) Where do the nerves originate in the CNS?
a. Thoracic vertebrae (T1-12) b. Lumbar vertebrae (L1-2)
(Parasympathetic Nervous System-craniosacral division) Where do the parasympathetic nerves originate in the CNS?
a. brain stem = "cranio" b. sacral spinal cord
The Parasympathetic Nervous System maintains what level of metabolism?
basal level of metabolism
What types of adrenergic receptors inhibit?
beta 1, 2, and 3: inhibits - causes relaxation (except beta cardiac receptors, which stimulate heart)
atropine (anti-Ach)
blocks parasympathetic secretions, used to dilate pupils (used to treat muscarine mushroom poisoning)
(Uniquely Sympathetic Functions) blood
blood - increased rate of coagulation
(Fill in the blank) The Parasympathetic Nervous System helps conserve ____________________
body energy
(Uniquely Sympathetic Functions) body temperature changes...
body temperature changes: sweat gland secretion increases; blood shunted to deeper organs
What drugs mimic neurotransmitters?
both nicotine (from tobacco) & muscarine (from poisonous mushrooms) mimic the effects of acetylcholine
(Uniquely Sympathetic Functions) brain
brain - increased alertness from RAS
(Parasympathetic Functions) constricts the...
bronchioles (calms breathing)
(Parasympathetic Functions) increases secretion of...
dig. glands
(Parasympathetic Nervous System) rest and ...
digest
alpha blockers
treat high blood pressure (since this blocks the alpha receptors, which stimulate vessel contraction)
Which drugs prolong activity of norepinphrine?
tricyclic antidepressants (elavil)