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NUR909 Module 4 (Respiratory Drugs) Exam
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NUR909 Module 4 (Respiratory Drugs) Exam- Let's keep the BRONCHIAL system separate from the pulmonary VASCULAR system to
avoid confusion - Answer :)
Through which receptor does the sympathetic nervous system cause bronchial smooth
muscle relaxation? (Bronchodilation) - Answer Beta 2
Through which receptor does the parasympathetic nervous system cause smooth
muscle contraction & increase mucous/secretion production? - Answer Muscarinic
Through what receptor does the sympathetic nervous system cause pulmonary vascular
vasoconstriction? - Answer Alpha 1
In smooth muscle, contraction is stimulated by the binding of calcium to which? A.
Calcium-calmodulin
Smooth Muscle Contraction
Where does this calcium come from? A. Outside the cell; the sarcoplasmic reticulum
Smooth Muscle Contraction
Calcium-calmodulin activates which of the following enzymes? A. Myosin light chain
kinase (MLCK)
Smooth Muscle Contraction
,What does myosin light chain kinase (MLCK) do? - Answer This enzyme phosphorylates
(adds energy) to the myosin light chain, which enables cross-bridging to actin filaments
Smooth Muscle Contraction
What does the myosin head do to the actin filaments? - Answer The myosin heads pull
the actin filaments towards one another
-Thus, shortening the muscle cell & producing contraction
-Contraction in bronchial smooth muscle cell is synonymous with bronchoconstriction
Summary Slide of Smooth Muscle CONTRACTION
1. Calcium enters the cytosol of smooth muscle & binds to a protein called calmodulin
2. The calcium calmodulin complex activates another protein, Myosin Light Chain
Kinase (MLCK) that phosphorylates myosin & thereby activates it
3. Activated myosin can now undergo the cross-bridge cycle & interact with actin
4. Myosin phosphatase removes a phosphate & is constantly taking phosphates off
myosin (always active) - Answer
For contraction of smooth muscle to occur, what must be true? - Answer There must be
more myosin kinase than myosin phosphatase (otherwise you have relaxation)
Summary Slide of Smooth Muscle RELAXATION
1. Myosin phosphatase > MLCK
2. Calcium stops being let in & calcium channels close -- now calcium is trapped & it
must be pumped out against its concentration gradient
a. Pumped into interstitial fluid via Ca++ ATPase
, b. Pumped into SR via Ca++ ATPase -- Correct
The more calcium in the cytosol, what can you say about the contraction? -- Correct The
stronger the contraction
What receptors are prolific on bronchial smooth muscle? -Answer Beta 2 receptors
What binds to beta 2 receptors? -Answer Norepinephrine or epinephrine
When these neurotransmitters are released from the sympathetic nervous system they
bind with, Beta 2 receptors on bronchial smooth muscle. What does this result in?
-Answer This results in the stimulation of the cAMP second messenger system
What does cAMP inhibit? - Answer Myosin light chain kinase (MLCK)
So if the myosin is never phosphorylated or energized, it will not be able to cross link
with actin & bronchial smooth muscle remains relaxed
So what is the result of no myosin-actin interaction? - Answer Bronchodilation
What 2 categories are beta 2 agonists divided into? - Answer 1. Short-acting
2. Long-acting
What do ALL beta 2 agonists share a similar molecular structure to? - Answer
Epinephrine
What can you note about the structure of long acting beta 2 agonists? - Answer They
also have a similar base structure, but add on longer side chains & aromatic rings
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