chapter 16.3 Flashcards
When stimulated, sympathetic preganglionic neurons release
acetylcholine (ACh) at synapses with ganglionic neurons. The effect on the ganglionic neurons is always excitatory.
What happens when the ganglionic neurons are stimulated?
These ganglionic neurons then release neurotransmitters at specific target organs.
What is varicosities?
he telodendria form a branching network, with each branch resembling a string of pearls. Each “pearl” is a swollen segment called a varicosity that is packed with neurotransmitter vesicles
What neurotransmitter is released from most varicosities in the sympathetic division?
Norepinephrine (NE) is released from most varicosities in the sympathetic division.
Neurons that release NE are called
adrenergic
Synapses that use ACh as a transmitter are called
cholinergic
Varicosities releasing ACh are located in
he body wall, the skin, the brain, and skeletal muscles.
What are two classes of these adrenergic receptors.
alpha receptors and beta receptors.
What Receptor does NE affect to a higher degree?
stimulates alpha receptors to a greater degree than it does beta receptors
What does E stimulate?
both classes of receptors
What are alpha and beta receptors
G-protein–coupled receptors.
What are the two types of alpha protein?
alpha-1 (α1) and alpha-2 (α2).
Describe alpha-1.
the more common type of alpha receptor, is found primarily in smooth muscle cells of many different organs. stimulation of α1 receptors on smooth muscle cells causes peripheral blood vessels to constrict and sphincters along the digestive tract and urinary bladder to close.
Describe alpha 2
receptors are found on preganglionic or postganglionic sympathetic neurons. The presence of α2 receptors in the parasympathetic division helps coordinate sympathetic and parasympathetic activities.
Where are beta receptors located
are located on the plasma membranes of cells in many organs, including skeletal muscles, the lungs, the heart, and the liver.
There are three major types of beta receptors
beta-1 (β1), beta-2 (β2), and beta-3 (β3).
Describe beta 1
leads to an increase in metabolic activity
The stimulation of β1 receptors in the heart increases heart rate and force of contraction.
Describe beta 2
causes inhibition, triggering the relaxation of smooth muscles along the respiratory tract.As a result, respiratory passageways dilate, making breathing easier.
Describe beta 3
Stimulation of β3 receptors leads to lipolysis, the breakdown of triglycerides stored within adipocytes.
Energy reserve, provides more ATP
A person with high blood pressure is given a medication that blocks beta receptors. How could this medication help correct that person’s condition?
Blocking the beta receptors on cells would decrease or prevent sympathetic stimulation of tissues containing those cells. Heart rate, force of contraction of cardiac muscle, and contraction of smooth muscle in the walls of blood vessels would decrease, lowering blood pressure.
How would a drug that stimulates cholinergic receptors affect the sympathetic nervous system?
Because preganglionic fibers of the sympathetic nervous system release acetylcholine (ACh), a drug that stimulates cholinergic receptors would stimulate the postganglionic fibers of sympathetic nerves, resulting in increased sympathetic activity.
