The peripheral nervous system (PNS), located outside the brain and spinal cord, is made up of two divisions:
1. the autonomic
2. the somatic
The autonomic nervous system (ANS), also called the ___________, acts on smooth muscles and glands.
visceral system
Functions of ANS
control and regulation of the heart, respiratory system, gastrointestinal tract, bladder, eyes, and glands
The ANS is an involuntary nervous system over which we have little or no control. True or False?
True
_______________ is a voluntary system that innervates skeletal muscles, over which there is control.
Somatic nervous system (SNS)
Two set of neurons in autonomic component of PNS
Afferent (Sensory neurons)
Efferent (Motor neurons)
The efferent pathways in the ANS are divided into two branches. What are these?
1. Sympathetic Nerve
2. Parasympathetic Nerve
Sympathetic nerve is also called the _________________.
adrenergic system
_____________ is the neurotransmitter that innervates smooth muscles.
Norepinephrine
Adrenergic receptor organ cells are of four types:
Alpha1
Alpha2
Beta1
Beta2
The sympathetic and parasympathetic nervous systems act on the same
organs but produce opposite responses to provide homeostasis (balance). True or False?
True
Drugs that stimulate the sympathetic nervous system
adrenergic agonists
adrenergics
sympathomimetics
When __________ receptors in vascular tissues (vessels) of muscles are
stimulated, the arterioles and venules constricts; this increase peripheral resistance and blood return to the heart, circulation improves, and blood pressure is increased. When too much stimulation occurs, blood flow decreased to the vital organs.
Alpha1
______receptor are in the postganglionic sympathetic nerve endings, when stimulated, they inhibit the release of norepinephrine, which leads to a decrease in vasoconstriction. This results in vasodilation and a decrease in blood pressure.
Alpha 2
Receptors are located primarily in the heart but are also found in the
kidneys. Stimulation of the this receptor increases myocardial contractility and heart rate.
Beta 1
__________ receptors are found mostly in the smooth muscle of the lung and GI tract, the liver, and the uterine muscle.
Beta 2
Other adrenergic receptor is _____________ and are located in the renal,
mesenteric, coronary, and cerebral arteries. When these receptor are
stimulated, the vessels dilate and blood flow increases. Only dopamine can activate this receptor.
dopaminergic
After the neurotransmitter (e.g., norepinephrine) has performed its function, the action must be stopped to prevent prolonging the effect. Transmitters are inactivated by:
(1) reuptake of the transmitter back into the neuron (nerve cell terminal),
(2) enzymatic transformation or degradation,
(3) diffusion away from the receptor.
The two enzymes that inactivate norepinephrine are:
(1) monoamine oxidase (MAO), which is inside the neuron; and
(2) catechol-O-methyltransferase (COMT), which is outside of the neuron.
(Classification of Sympathomimetic) directly stimulate the adrenergic receptor (e.g., epinephrine or norepinephrine)
Direct-acting sympathomimetics
(Classification of Sympathomimetic) stimulate the release of norepinephrine from the terminal nerve endings (e.g., amphetamine)
Indirect-acting sympathomimetics
(Classification of Sympathomimetic) (both direct and indirect-acting), which stimulate the adrenergic receptor sites and stimulate the release of norepinephrine from the terminal nerve endings (e.g., ephedrine)
Mixed-acting sympathomimetics
________________ is an example of a mixed-acting sympathomimetic.
This drug acts indirectly by stimulating the release of norepinephrine from the nerve terminals and acts directly on the alpha1 and beta1 receptors; like epinephrine, increases heart rate
Pseudoephedrine
Pseudoephedrine is helpful to relieve nasal and sinus congestion without rebound congestion. True or False?