Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
19 Cards in this Set
- Front
- Back
|
Besides functional classification such as tonic vs. phasic... what other functional classifications can smooth muscle have?
Give examples of both and briefly explain them... |
a. Multi unit- organs all behave independently (vasculature) less gap junction
b. single unit- all act as one (gi tract), often rhythmic, have many gap junctions |
|
|
Where is neurotransmitters released from in neurons to smooth muscle?
Explain how this differs from skeletal muscle. |
1. varicosities around muscle, release many neurotransmitters some inhibit the muscle
|
|
|
Explain three general effects and where is it released and why of each of the following neurotransmitters...
a. epinephrine/norepinephrine |
a. released by the adrenal medulla in response to sympathetic activation.
b. Alpha and beta receptors |
|
|
Explain three general effects and where is it released and why of each of the following neurotransmitters...
1. acetylchonline |
1. released by parasympathetic neurons & the some neurons in the intrinsic innervation of gut, trachea.
2. Cause contraction via muscarinic receptors (connected to G protein - 3. In vasculature, a few other places, indirectly (i.e. acting through a secondary agent) causes relaxation of smooth muscle. |
|
|
Explain three general effects and where is it released and why of each of the following neurotransmitters... What is it known as?
1. nitric oxide |
1. Release by intrinsic nervous system of gut & trachea and CNS neurons, endothelial cells of the vasculature and cells of the immune system.
2. Formed by nitric oxide synthase takes arginine into NO and citrulline. 3. controlled by the presence of calcium in the neuron/cell 4. Very lipid soluble - diffuses out of neuron and into surrounding cells without benefit of receptor. 5. activates the production of cGMP. 6. The major inhibitory neurotransmitter causing relaxation of smooth muscle in the GI tract, and it is a significant contributor to the relaxation of vascular smooth muscle (Ach causes release of NO in the vasculature). |
|
|
Name which neurotransmitter fits the following descriptions...
a. major inhibitory neurotransmitter in GI,, does not need receptor to enter cell b. requires cyclo-oxygenase and arachidonic acid for production c. one of the most potent causes of contraction of vascular smooth muscle |
a. nitric oxide
b. postacyclin c. ET (endothelin) |
|
|
Explain three general effects and where is it released and why of each of the following neurotransmitters... What is it known as?
a. adenosine b. prostacyclin |
a. causes inhibition and relaxation of vascular smooth muscle.
b. 1. Also known as PGI2 - requires cyclo-oxygenase and arachidonic acid for production. 2. released by the endothelial cells into the vicinity of the smooth muscle cells. 3. Binds to a cell surface receptor (IP) that leads to the production of cAMP. |
|
|
Explain three general effects and where is it released and why of each of the following neurotransmitters... What is it known as?
a. Endothelin (ET) |
1. Family of three 21 amino acid peptides (ET-1, ET-2, and ET-3).
2. Causes contraction of vascular smooth muscle (one of the most potent found in the human body). |
|
|
How are smooth muscles activated or inhibited differently than skeletal (general sense examples)
|
1. hormones... (acytocholine, oxytocin, epinephrine, CCK) - angiotensin I and II
2. paracrine agents- EDRF (NO), and EDHF- opens K+ channel |
|
|
Explain the three main ways that smooth and skeletal muscle excitation contraction and energy coupling differ... Also skeletal muscle uses 1 ATP but smooth uses how many per contraction cycle?
|
1. the source of the calcium (relying both on extracellular and intracellular sources).
2. how calcium is released into the intracellular space 3. how the calcium is used to initiate the contraction. 4. ATP used by smooth per contraction (2) |
|
|
What is role of IP3 in smooth muscle contraction and how is it made?
|
IP3 opens calcium channels of SR...
IP3 is created after Gq proteins receive agents and sends message |
|
|
What element causes depolarization?
|
- First ligand gated Ca channels open which causes voltage gated Ca channels to open
- No Na channels in smooth muscle |
|
|
What role does the following have in smooth muscle contraction?
a. calmodulin b. Myosin light chain kinase (MLCK) b. |
a. once 4- Ca's bind to it.. it activates MLCK
b. phosphorylates one of the two light chain head of myosin... the myosin head develops a high affinity for the actin active site and binds |
|
|
Knowing that smooth muscles needs to contract more and it uses more ATP, yet it does not have as many mitochondria... how does it compensate?
|
1. contractions are longer, meaning less often
2.Latch mechanism - myosin can be dephosphorylated at any point of contraction, causing contraction to continue but very slowly 3. Ca pumps in side SR pumping out |
|
|
Describe the two ways in which chemicals cause inhibition in the smooth muscle
|
1. Secondary messenger that eventually increases cGMP (NO) or cAMP (prostacyclin or norepinephrine) which increase Ca removal and decrease Ca release
2. hyperpolarization- EDHF binds to a receptor on the smooth muscle cell membrane and activates a potassium channel- (since cell hyperpolarizes Ca voltage gated wont open) |
|
|
Describe the process of when smooth muscle gets signals to lose its contractile apparatus and become a secretory cell? the reverse process?
|
Once given signal can do things like secrete collagen...
Known as... modulation Reversed is maturation |
|
|
Explain why smooth muscle can continue to generate tension over a much wider range of lengths than skeletal muscle... Why is that?
|
1) a less restrictive arrangement of the myosin cross bridges
2) many more actin filaments. basically the myosin head can always find a new active site to interact with and create tension. |
|
|
Compare and contrast excitation- contraction coupling in smooth and skeletal muscle...
|
Smooth-
1. use of gap junctions allows spread of activation from one cell to another, 2. myosin: 1/4 compared to skeletal a. slower on pump b. kinase and phosphatase (adding/removing phosphate groups) 3. actin: 2x as much in skeletal a. no troponin b. calmodulin |
|
|
What are the two types of smooth muscle classifications?
Describe examples of each... |
1. Rythmic or Phasic- when used it goes in rhythm but usually at rest (intestines, bladder)
2. Tonic or continuous- spends most of time contracted- (lower esophogeal sphincter, vascular smooth muscle) |
