What is the origin of the Sympathetic Division?
Fibers originate in the thoracic and lumbar spinal cord, T1-L2
What is the origin of the Parasympathetic Divison?
Fibers originate in the brain stem through cranial fibers or in the inferior sacral spinal cord
Name 3 functions of the Sympathetic Division
Constricts visceral and sometimes cutaneous blood vessels, this shunts blood to active skeletal muscles and the heart
dilates the bronchioles in the lungs, increasing airflow and increasing oxygen delivery to blood cells
stimulates the liver to release more glucose into the blood to accommodate the increased energy needs of body cells
Name 3 functions of the Parasympathetic Division
blood pressure and heart rate are regulated at low normal levels
active digestion of food in gastrointestinal tract
eliminating feces and urine
What is the overall function of the Vagus nerve?
Cervical plexus nerve that contains fibers from both the parasympathetic and sympathetic divisions
supplies virtually every organ in the thoracic and abdominal cavities
What is the origin of the Vagus nerve?
Where do they synapse?
Preganglionic axons of the Vagus nerve originate from the dorsal motor nuclei of the medulla
synapse in the terminal ganglia usually located in the walls of the target organ
Name 3 things the vagus nerve innervates
Cardiac plexus which supplies fibers to the heart that slow the heart rate
Pulmonary plexus that serves the airways of the lungs
Esophageal plexus which serves the esophagus and part of the stomach
Define "referred pain"
Visceral pain afferent fibers travel in the same paths as somatic pain fibers and arrive at the same spinal cord segment
This is why pain stimuli from the viscera are perceived as somatic pains
define "Dynamic Equilibrium"
The body maintains internal conditions at a relatively narrow range to maintain homeostasis amidst constantly changing internal and external conditions
Define "dual Innervation"
Both autonomic divisions serve the same visceral organs but cause opposite effects
While one stimulates certain smooth muscles to contract or a gland to secrete, the other inhibits action
what are the effects of the parasympathetic nervous system on the adrenal medulla?
the effects of the sympathetic nervous system?
parasympathetic - no effect
sympathetic - secretes epinephrine and norepinephrine
List the unique functions of the Sympathetic Division
Thermoregulatory responses to heat
Release of renin from the Kidneys
Metabolic effects
Describe the thermoregulatory response to heat in the Sympathetic Divison
When systemic body temperature rises, sympathetic nerves
—> dilate the skin’s blood vessels allowing heat to escape
—> active the sweat glands to help cool the body
When systemic body temperature falls, sympathetic nerves
—> skin blood vessels constrict preventing heat loss from the skin
Describe the release of renin from the Kidneys in the Sympathetic Division
Sympathetic impulses stimulate the kidneys to release renin, an enzyme that causes the formation of potent blood-pressure increasing hormones
Describe the Metabolic Effects in the Sympathetic Divison
Through both direct neural stimulation and the release of adrenal medullary hormones, the sympathetic division promotes metabolic effects not reversed by parasympathetic activity
-Increases the metabolic rate of body cells
-Raises blood glucose levels
-Mobilizes fats for use as fuels
state which division of the autonomic nervous system has a quicker response time and why
sympathetic nervous system
shorter nerve pathways
faster-acting neurotransmitter
role in fight or flight response
what level of control does the hypothalamus have over the ANS?
emotional responses of the limbic system to danger and stress signal the hypothalamus to activate the sympathetic system
what level of control does the brainstem have over the ANS?
most direct influence over autonomic functions
cardiac and vasomotor centers
medullary regions oversee gastrointestinal activities
vagus nerve sends afferents to brain
oculomotor nuclei controls muscles concerned with pupil diameter and lens focus
what level of control does the spinal cord have over the ANS?
reflexes for urination, defecation, erection, and ejaculation
why are alpha blocker drugs effective in treating hypertension?
Alpha-blocker drugs prevent Epinephrine secreted from adrenal glands from the Sympathetic Division origin from binding to their target receptors on the post-ganglionic neuron
This reduces the amount of vasoconstriction on blood vessels decreasing hypertension in the body
What is sympathetic tone?
what effect does it have on blood vessels?
Vascular system almost entirely innervated by sympathetic division
Keeps blood vessels in constant partial constriction
what is Parasympathetic Tone?
Slows heart rate and Dictates normal activity of digestive and urinary tracts
what are visceral reflexes?
Visceral sensory neurons send information about chemical changes, stretch and irritation of viscera
what is innervated by the sympathetic divison, but not the parasympathetic divison?
adrenal gland
sweat gland