autonomic nervous system (ANS) or visceral motor system
a motor nervous system that controls glands, cardiac muscle and smooth muscle
- carries out its actions involuntarily, without our conscious intent or awareness, in contrast to the voluntary nature of the somatic motor system
- receives input from limbic
visceral reflexes
unconscious, automatic, stereotyped responses to stimulation, much like the somatic reflexes but involving visceral receptors and effectors and slower responses
parasympathetic division
associated with reduced energy expenditure and normal bodily maintenance, including such functions as digestion and waste elimination. This can be thought of as the "resting- and-digesting" state.
autonomic tone
the balance between sympathetic tone and parasympathetic tone shifts in accordance with the body's changing needs
preganglionic fiber
The first fiber, called the preganglionic fiber, leads from a soma in the brainstem or spinal cord to the autonomic ganglion. It synapses there with a neuron that issues a postganglionic fiber to the target cells.
postganglionic fiber
In contrast to somatic motor neurons, postganglionic fibers of the ANS do not end by synapsing with a specific target cell, but with a chain of varicosities that diffusely release neurotransmitter into the tissue and stimulate many cells simultaneously.
sympathetic chain of ganglia (paravertebral ganglia)
a longitudinal series of ganglia that lie adjacent to both sides of the vertebral column from the cervical to the coccygeal level. They are interconnected by longitudinal nerve cords.
white communicating ramus
- an anatomical branch
- the preganglionic fibers are small myelinated fibers that travel from the spinal nerve to the ganglion by way of the white communicating ramus
gray communicating ramus
named for its lack of myelin and duller color, and by other routes. This ramus forms a bridge back to the spinal nerve. Postganglionic fibers extend the rest of the way to the target organ.
spinal nerve route
Some postganglionic fibers exit a ganglion by way of the gray ramus, return to the spinal nerve or its subdivisions, and travel the rest of the way to the target organ. This is the route to most sweat glands, piloerector muscles, and blood vessels of the
sympathetic nerve route
Other postganglionic fibers leave by way of sympathetic nerves that extend to the heart, lungs, esophagus, and thoracic blood vessels. These nerves form a carotid plexus around each carotid artery of the neck and issue fibers from there to effectors in th
splanchnic nerve route
Some of the fibers that arise from spinal nerves T5 to T12 pass through the sympathetic ganglia without synapsing. Beyond the ganglia, they continue as splanchnic nerves, which lead to a second set of ganglia called collateral (prevertebral) ganglia. Here
adrenal (suprarenal) glands
1. adrenal cortex - (outer rind) secretes steroid hormones discussed in chapter 17
2. adrenal medulla - (inner core) secretes a mixture of hormones into the bloodstream�about 85% epinephrine (adrenaline), 15% norepinephrine (noradrenaline), and a trace of
parasympathetic division or craniosacral division
The branch of the autonomic nervous system that generally conserves bodily resources.
1. Oculomotor nerve (III). The oculomotor nerve carries parasympathetic fibers that control the lens and pupil of the eye. The preganglionic fibers enter the orbit and t
enteric nervous system
The digestive tract has a nervous system of its own called the enteric nervous system.
Acetylcholine (ACh)
ACh is secreted by the preganglionic fibers in both divisions and the postganglionic fibers of the parasympathetic division (table 15.4). A few sympathetic postganglionics also secrete ACh�those that innervate sweat glands and some blood vessels. Any nerv
Muscarinic receptors
These are named for muscarine, a mushroom toxin used in their discovery. All cardiac muscle, smooth muscle, and gland cells that receive cholinergic innervation have muscarinic receptors. There are different subclasses of muscarinic receptors with differe
Nicotinic receptors
These are named for another botanical toxin helpful to their discovery�nicotine. They occur at all synapses in the autonomic ganglia, where the preganglionic fibers stimulate the postganglionic cells; on cells of the adrenal medulla; and at the neuromuscu
Norepinephrine (NE)
This neurotransmitter is secreted by nearly all sympathetic postganglionic fibers. Nerve fibers that secrete it are called adrenergic fibers, and the receptors for it are called adrenergic receptors. (NE is also called noradrenaline, the origin of the ter
?-adrenergic receptors (alpha)
These usually have excitatory effects. For example, the binding of NE to ?-adrenergic receptors promotes labor contractions, stimulates piloerection, and constricts dermal blood vessels, yet it inhibits intestinal motility. These contrasting effects resul
?-adrenergic receptors
These are usually inhibitory. For example, NE relaxes and dilates the bronchioles (thus enhancing respiratory airflow) when it binds to ?-adrenergic receptors of the smooth muscle. Yet when it binds to the
- usually inhibitory
- works by a cAMP second mes
dual innervation
Most of the viscera receive nerve fibers from both the sympathetic and parasympathetic divisions and thus are said to have dual innervation.
- have either antagonistic or cooperative effects on the same organ
Antagonistic effects
oppose each other.
Cooperative effects
Effect in which two hormones, or both divisions of the autonomic nervous system, work together to produce a single overall result.
unified
hypothalamus
The inferior portion of the diencephalon of the brain, forming the walls and floor of the third ventricle and giving rise to the posterior pituitary gland; controls many fundamental physiological functions such as appetite, thirst, and body temperature an
Horner syndrome
Chronic unilateral pupillary constriction, sagging of the eyelid, withdrawal of the eye into the orbit, flushing of the skin, and lack of facial perspiration, resulting from lesions in the cervical ganglia, upper thoracic spinal cord, or brainstem that in
Raynaud disease
Intermittent attacks of paleness, cyanosis, and pain in the fingers and toes, caused when cold or emotional stress triggers excessive vasoconstriction in the digits; most common in young women. In extreme cases, causes gangrene and may require amputation.
Autonomic Nervous system
a motor nervous system that controls glands, cardiac muscle, and smooth muscle
Denervation hypersensitivity
exaggerated response of cardiac and smooth muscle if autonomic nerves are severed
Visceral reflexes
unconscious, automatic, stereotyped responses to stimulation involving visceral receptors and effectors and somewhat slower responses
Receptors
nerve endings that detect stretch, tissue damage, blood chemicals, body temperature, and other internal stimuli
Autonomic tone
normal background rate of activity that represents the balance of the two systems according to the body's changing needs
Preganglionic fibers
are small myelinated fibers that travel from spinal nerve to the ganglion by way of the white communicating ramus (myelinated)
Postganglionic fibers
leave the ganglion by way of the gray communicating ramus (unmyelinated) � Forms a bridge back to the spinal nerve
Postganglionic fibers
extend the rest of the way to the target organ
Solar plexus
collective name for the celiac and superior mesenteric ganglia
� Nerves radiate from ganglia like rays of the sun
Enteric nervous system
the nervous system of the digestive tract
- Does not arise from the brainstem or spinal cord
- Does innervate smooth muscle and glands
Composed of 100 million neurons found in the walls of the digestive tract
� No components in CNS
� Has its own reflex ar
Megacolon
massive dilation of bowel accompanied by abdominal distension and chronic constipation May be colonic gangrene, perforation of bowel, and peritonitis
- Usually evident in newborns who fail to have their first bowel movement
Muscarinic receptors
All cardiac muscle, smooth muscle, and gland cells have muscarinic receptors
� Excitatory or inhibitory due to subclasses of muscarinic receptor
Nicotinic receptors
On all ANS postganglionic neurons, in the adrenal medulla, and at neuromuscular junctions of skeletal muscle
� Excitatory when ACh binding occurs
- occur at synapses of all autonomic ganglia, on cells of the adrenal medulla and at the neuromuscular juncti
Dual innervation
most viscera receive nerve fibers from both parasympathetic and sympathetic divisions
Antagonistic effects
oppose each other
- Exerted through dual innervation of same effector cells
� Heart rate decreases (parasympathetic)
� Heart rate increases (sympathetic)
- Exerted because each division innervates different cells
� Pupillary dilator muscle (sympathetic) d
Cooperative effects
when two divisions act on different effectors to produce a unified effect
- Parasympathetics increase salivary serous cell secretion
- Sympathetics increase salivary mucous cell secretion
Hypothalamus
major visceral motor control center
� Nuclei for primitive functions�hunger, thirst, sex
Cerebral cortex
has an influence: anger, fear, anxiety
� Powerful emotions influence the ANS because of the connections between our limbic system and the hypothalamus
Neuropharmacology
study of effects of drugs on the nervous system
Sympathomimetics
enhance sympathetic activity - Stimulate receptors or increase norepinephrine release
� Cold medicines that dilate the bronchioles or constrict
nasal blood vessels
Sympatholytics
suppress sympathetic activity
- Block receptors or inhibit norepinephrine release
� Beta blockers reduce high BP interfering with effects of
epinephrine/norepinephrine on heart and blood vessels
Afferent neurons
leading to the CNS
Efferent neurons
carry motor signals away from the CNS
Effectors
that make adjustments
Adrenal Medulla Hormones.
Norepinephrine, Epinephrine (catecholamines) Secretes mainly Epnephrine (80%) and a small amount of Norepinephrine (20%)
autonomic
the nervous system division that has effectors that are glands, smooth muscled and cardiac muscle
thoracolumbar
the sympaythetic nervous system is also called the _____ division as it arises from the thoracic and lumbar regions of the spinal crd
cranial nerves III, VII, IX and X
carry parasympathetic fibers from the brainstem
preganglionic neuron
its cell body is in the brain or spinal cord, and its axon exits the CNS as part of a cranial or spinal nerve.
fight or flight, rest and digest
Because of he location of the preganglionic cell bodies, the sympatheric division of the ANS is aslo called the _______division, the parasympathetic division is also called the _______ division.
vagus nerve
the cranial nerve that supplies parasympathetic fibers to viscera of the thoracic and abdominopelvic cavities
reduced energy expenditure, digestion, waste elimination, normal body maintenance
the activities attributed to the parasympathetic nervous system
Identify the correct pairing of the components of the adrenal gland:
medulla: the inner part
The parasympathetic division arises from the _______ and the _______.
Brainstem, sacral spinal cord
Regulation of pupillary constriction and dilation is an example of the ____ effects of the sympathetic and parasympathetic divisions on the same organ.
antagonistic
From which region of the CNS do the nerves of the parasympathetic nervous system arise?
brainstem, sacral
THe axons of the white communicating ramus are ____ and _____ and _____.
Myelinated, preganglionic, sympathetic
the division of the ANS that is responsible for increasing heart rate, alertness, blood pressure, pulmonary airflow, blood-glucose concertration, and blood flow to the heart and skeletal muscles.
Sympathetic division.
SOMATIC
the nervous system division that has skeletal muscles as effectors
- transmits only excitatory signals to its effector cells
Indicate which of the following are autonomic reflexes regulated by the spinal cord.
Ejaculation, defecation, erection, micturition
Name the division of the ANS that is associated with the "fight-or-flight" response.
Sympathetic
Identify those cranial nerves that carry parasympathetic fibers from the brainstem.
(IX) glossopharyngeal, (III) oculomotor, (x) vagus, 7, (VII) facial.
Sympathetic, unmyelinated, postganglionic
Axons of the grey communicating ramus are___ and _____
how a neuron generates electrical signals
movement of ions through channels generate and electrical charge difference (voltage) across the membrane
name the structures that are innervated by parasympathetic fibers which arise from S2-S4.
rectum, reproductive organs, urinary bladder.
Identify the cranial nerve that supplies parasympathetic fibers to viscera of the thoracic and abdominopelvic cavities.
X
The cell bodies of sympathetic preganglionic fibers are found in the ____ horn of the T1-L2 spinal cord.
Lateral
Indicate the regions of spinal cord from which the nerves of the sympathetic nervous system arise.
Thoracic, lumbar
Sweating, vasomotor control, pupillary constriction, salivation
Indicate which of the following are regulated by autonomic nuclei in the brainstem
the division of the ANS that is responsible for the following effects on the reproductive system: penile or clitoral engorgement and stimulation of glandular secretion.
Parasympathetic
Identify the neurons that secrete acetylcholine:
Most postganglionic parasympathetic neurons, most preganglionic sympathetic neurons, most preganglionic parasympathetic neurons.
List the functions of the enteric nervous system.
Regulates the secreton of digestive enzymes, regulates motility through the digestive tract.
Neurons in the _____ nervous system division secrete only acetylcholine.
somatic
____ _____ describes the continual input from the sympathetic division to smooth muscle of blood vessels, resulting in a partial and constant tension in the blood vessel wall.
Vasomotor tone
Anxiety, Anger, Fear
the stimuli trigger the limbic system to influence hypothalamic control of the ANS.
Name the cranial nerve that regulates secretion from the tear glands, the salivary glands and the nasal glands.
Facial (VII)
which of the following are only innervated by sympathetic nerve fibers
adrenal medulla, pilorector muscles, sweat glands
The neurotransmitter norephinephrine binds to _____ receptors.
adrenergic
The adrenal medulla is made of modified ______ neurons.
Postganglionic sympathetic
TWO, 2
the number of nerve fibers connecting the CNS and the effector in the ANS
All receptors that bind to ACh are referred to as _____ receptors.
Cholinergic
If the nerves to visceral effectors are severed, the effectors exhibit _____.
Hypersensitivity
Sympathetic
the division of the ANS that has relativley short preganglionic fibers and long postganglionic fibers
Parasympathetic
the division of the ANS that has relativley long preganglionic fibers and short postganglionic fibers
Acetylcholine
the neurotransmitter released by both preganglionic and postganglionic neurons of the parasympathetic division
In the circulation, _____ occurs in response to the lowest rate of sympathetic nerve firing to the smooth muscle cells of the blood vessels.
vasodilation
the division of the ANS that has the following effects on the urinary system: contraction of the urinary bladder wall and relaxation of the internal urethral sphincter.
Parasympathetic
the division of the ANS that has the following effects on the urinary system: reduced urine output by the kidneys and contraction of the internal urethral sphincter.
Sympathetic
the parasympathetic effects on the digestive system?
Increased pancreatic enzyme secrection, increased gastrointestinal secretion, increased gastric motility.
Name the plexuses that receive parasympathetic fibers from the vagus nerve.
Cardiac plexus, pulmonary plexus, esophageal plexus.
After entering the sympathetic chain, preganglionic fibers can end up in 3 places
1. Ganglion that they enter and synapse immediately with postganglionic neuron; 2. Travel up & down chain and synapse in ganglia at other levels; 3. Some pass through chain without synapsing and continue as splanchnic nerves
The _____ division of the ANS may induce the increased or decreased breakdown of adipose tissue.
Sympathetic
Muscarinic
receptors that can be inhibited or excited by the binding of acetylcholine ACh
Glossopharyngeal nerve
crainal nerve that carries parasympathetic fibers which regulate the secretion of the salica from the parotid gland
Indicate which of the following are sympathetic effects on the integumentary system.
Secretion from apocrine sweat glands, secretion for merocrine sweat glands.
Indicate which are sympathetic effects on the circulatory system.
Increased blood clotting, vasoconstriction of visceral blood vessels, vasoconstriction of blood vessels in the skin, increased heart rate.
The ______ ______ plexus is a network of sympathetic and parasympathetic axons that wrap around the aorta.
Abdominal aortic.
Name the three collateral ganglia of the abdominal plexus.
Caliac, superior mesenteric, and inferior mesenteric ganglia
Name the fibers types found in the pelvic splanchnic nerves.
Preganglionic parasympathetic fibers.
Identify the division of the ANS that stimulates secretion of hormones by the adrenal medulla.
Sympathetic