Question | Answer |
ANS regulates .. | ...fundamental life sustaining functions |
ANS manages .. | ..processes responsible for homeostasis and survival |
ANS is a visceral ... | ..motor nervous system |
ANS controls... | ..glands, cardiac muscle, and smooth muscle |
ANS target organs are.. | ..viscera of the thorax and abdomino-pelvic cavities, body wall, and skin |
Visceral reflex | unconscious, automatic, stereotyped response to stimuli |
Reflex Arc | Receptors afferent neurons to the CNS interneurons in the CNS efferent neurons effectors |
The SNS and PNS often innervate.. | ...the same target organs and may have cooperative or contrasting effects on them |
Sympathetic Nervous System (SNS) | Adapts the body for physical activity (fight-or-flight) |
SNS | .Occurs when involved in arousal, exercise, competition, stress, danger, trauma, anger, and fear |
Parasympathetic Nervous System (PNS) | It has a calming effect on body functions (resting and digesting) |
PNS | It is associated with reduced energy expenditure and normal body maintenance |
Autonomic tone | the balance between the SNS tone and PNS tone which shifts according to the body’s changing needs |
ANS components | nuclei in the hypothalamus and brainstem, motor neurons in the spinal cord, peripheral ganglia, cranial and spinal nerves |
Preganglionic fiber | axon that leads from a soma in the brainstem or spinal cord to the autonomic ganglion |
Postganglionic fiber | axon of a soma in the ganglion that goes to the target cells |
Synapse is between .. | ...Pre and Post neurons in the ganglion |
SMS innervates.. | ..skeletal muscle and is voluntary |
SMS uses... | ..one nerve fiber from the CNS to the effector and has no ganglion |
The Sympathetic Division | (thoraco-lumbar) |
Preganglionic fibers SMS | somas are in the spinal cord T1-L2, axons go to the sympathetic chain of the paravertebral ganglia |
Paravertebral ganglia | series of ganglia adjacent to the vertebral from cervical to coccygeal level |
Spinal nerve route | fibers exit the ganglion and return to a spinal nerve that innervates the skin structures and skeletal muscles |
Sympathetic nerve route | fibers exit by way of sympathetic nerves which innervate the head and thoracic cavity |
Splanchnic nerve route | preganglionic fibers pass through the ganglia and synapse in the celiac, superior and inferior mesenteric ganglia which innervate organs of the abdomino-pelvic cavity |
Adrenal glands | rest on top of the kidneys |
The adrenal medulla | is stimulated by preganglionic fibers and secretes epinephrine and norepinephrine |
The Parasympathetic Division | (craniosacral division) |
Preganglionic fibers PNS | somas are in the brainstem and the spinal cord, their axons travel in cranial nerves III, VII, IX, X and S2-S4 to target organs |
Preganglionic fibers end in.. | ..terminal ganglia in or near the target organ and synapse with post ganglionic fibers |
Enteric nervous system | nervous system of the digestive tract |
ENS innervates.. | ..smooth muscles and glands of the esophagus down to the colon to regulate motility and secretion of enzymes |
The SNS and PNS can have.. | ..different effects on an single organ |
SNS and PNS fibers ... | ..secrete different neurotransmitters |
Target cells respond .. | ..in different ways to a neurotransmitter |
Ach from cholinergic fibers is ... | ..secreted by all preganglionic fibers and postganglionic fibers of all PNS and the SNS that innervate sweat glands and blood vessels |
Muscarinic receptors | on cardiac muscle, smooth muscle, and gland cells with differing results |
Nicotinic receptors | on postganglionic cells in autonomic ganglionic, cells of the adrenal medulla and on skeletal muscle cells with excitatory results |
Norepinephrine | secreted by all SNS postganglionic (adrenergic) fibers |
Choligernic Receptors | Muscarinic and Nicotinic |
Alpha- adrenergic receptors | usually excitatory but does inhibit intestinal motility |
Beta-adrenergic receptors | usually inhibitory, but does excite the cardiac muscle |
Sympathetic effects last longer than parasympathetic effects because .. | ..Ach is broken down quickly whereas NE can enter the blood stream and last for several minutes |
Dual innervation | most viscera receive innervation from both divisions |
Antagonistic effects | oppose each other either at the same effector cells or different effector cells with opposite effects |
Cooperative effects | SNS and PNS act on different effectors to produce a unified overall effect |
ANS opposite effects ... | ..on an organ with SNS |
The adrenal medulla, pilorector muscles, sweat glands and many BV, have only .. | ..SNS fibers |
Vasomotor tone | baseline sympathetic tone which keeps vessels partially constricted |
Increase in firing rate ... | ..constricts a vessel by increasing smooth muscle contraction |
Decrease in firing rate.. | ...dilates a vessel by allowing the smooth muscle to relax |
Cerebral cortex | the limbic system which is involved in emotions provides a pathway connecting sensory and mental experiences with the ANS |
Hypothalamus | major control center of the visceral motor system |
Midbrain, pons, and medulla oblongata | house autonomic nuclei, output travels via spinal cord and cranial nerves III, VIII, IX, X |
Spinal cord | Spinal cord- integrates autonomic reflexes such as urination and defecation |