Lecture 10/11 Flashcards
End Test 2
What does the Length-Tension graph show?
How well the muscle is being stretched out
Active tension
What happens to the H-band during a contraction?
Doesnt change
T/F: Myosin stretches wide
F
Myosin has a fixed width; cant stretch/compress
What happens when a muscle is over/under stretched in skeletal muscle?
AP wont produce much force/contraction
What is the optimal stretch of a skeletal muscle sacromere?
2 micrometers
What is active tension?
Force generated when shocked and AP generated
How do you calculate active force?
apply force transducer at top of muscle
apply wt at bottom of muscle for passive tension
The measurement the transducer gives now is PASSIVE TENSION
Shock the muscle
The measurement the transducer gives during the shock is the TOTAL TENSION
Active tension = total tension - passive tension
What is passive tension?
outside force used to over/under stretch a sacromere
What is the equation for total tension?
Active tension + Passive tension
What happens to velocity as you increase the weight?
The velocity decreases
With a lighter load the muscle can shorten ______
faster
With a heavier load, the muscle will shorten _______
slower, if at all
What happens in the heart if you increase weight, which decreases velocity?
Heart failure
What is summation?
Measurement of first full contraction
5hz/sec
When does tettany happen?
40 Hz/s
At what rate of contraction is the muscle unable to go back to baseline?
12 Hertz per second
What is tettany?
When we lose twitches d/t so much Ca++ in the cell from rapid AP saturating the Ca++ receptors
Define Quantal (#)
Recruiting more motor units, or larger ones, when needing to produce more force
Dependent on electrical activity
Why does tettany happen?
The contractions are happening so fast that calcium is unable completely returned back to the SR, causing calcium buildup in the cell.
What happens to your muscles during atrophy?
Muscles has been inactive for an extended period of time
Decrease in number of myofibrils or even skeletal muscle cells causing the overall size of the muscle to shrink
skeletal muscle cells are hard to replace
What happens to your muscles during hypertrophy?
Normally d/t exercise
Increase in the number of myofibrils and size of large blood vessles causing the size of the muscle to increase.
What happens to your muscles during hyperplasia?
Generating new skills or muscle cells at a very low rate.
Cell division increases risk for cancer
How much of our body weight is smooth muscle?
10%
T/F: skeletal muscle is stronger than smooth muscle
F
Smooth muscle a stronger per gram
What is the ratio of Actin to myosin in Skelton muscle?
2:1
What is the ratio of actin to myosin and smooth muscle?
10-20:1
What anchors the actin together in smooth muscle? (acts as z-disc)
Dense bodies
Describe the SR in smooth muscle?
Dependent on outside Ca++
Underdeveloped
How many times can the skeleton muscle contract before running out of calcium in the SR?
1000s
T/F: in smooth muscle, it takes longer for the myosin head to release from F-actin
T
Describe the latch mechanism in smooth muscle
The cross bridge cycling is slower in smooth muscle compared to skeletal muscle. Therefore it can maintain that contraction for a longer time with less energy being used.
What gives smooth muscle vessels it’s tone?
Leaky Ca++ channels
What happens when there is no calcium in the blood?
You will have no BP, because calcium gives the blood vessels its tone.
What are the two things that contribute to vascular tone?
Ca++
The heart pumping blood
What is another name for a visceral smooth muscle?
Unitary smooth muscle
Describe, visceral smooth muscle
“Unitary smooth muscle”
Behaves as a unit
Has gap junctions therefore neighboring cells are effected
What type of smooth muscle is most of our body?
Visceral muscle
Hollow organs are normally _____ muscle
visceral
How does multiunit, smooth muscle tissue communicate?
Through neurotransmitters released in the area
What is multiunit smooth muscle used for?
Fine-tuning
Small amounts of force
Examples of multiunit smooth muscles
Ciliary muscles in the eye
Iris muscle in the eye to determine how much light gets in
What type of smooth muscle is used in the esophagus?
hybrid visceral and multiunit smooth muscle
What are the three layers of smooth muscle in blood vessels? and where are they?
Endothelial layer - innermost
Vascular smooth muscle - middle
Adventitia - outter and structural layer
Which layer of smooth muscle in the blood vessels lines the entire cardiovascular system?
Endothelial layer
What is another name for the endothelial layer?
Tunica Intima
What is another name for the vascular smooth muscle layer?
Tunica media
What is another name for the adventitia layer?
Tunica Adventitia
Which two layers in smooth muscles in the blood vessels communicate the neurotransmitters?
Tunica Intima (endothelial)
Tunica Media (vascular smooth muscle)
capillaries only have_________ and no smooth muscle
endothelium
T/F: smooth muscle sacromeres have a M-line
F
T/F: smooth muscle can shorten to more than half their length
T
What are some differences between the Sacromere of the skeletal muscle and smooth muscle?
Orientation of the myosin head
No M-line
Can shorten a lot more
What does acetylcholine receptors do in the small intestine?
Contracts
What does acetylcholine receptors do in the blood vessels?
Relax
What does tropomysin do in smooth muscle?
Nothing
What does calmodulin do in smooth muscle?
binds to calcium and activates MLCK
What does MLCK do in smooth muscle?
Cycles ATP and phosphorylates and activates the regulatory light chain myosin head
MLCK =
Myosin Light Chain Kinase
Describe the smooth muscle contraction pathway
- Smooth muscle enters the cell via the SR, L-type channels, or Ca++ ion channels
- Calmodulin binds to calcium
- Calmodulin and calcium activate MLCK
- MLCK cycles ATP, and phosphorylates and activates the regulatory myosin light chain
- The myosin regulatory light chain pulls on the actin, causing a shortening of the Sacromere, which causes a contraction
Are actin active sites, hidden in smooth muscle?
No
Kinase =
Phosphatase =
adds a phosphate
takes away a phosphate
What does decreasing calcium in smooth muscle do?
muscle relaxation
What does myosin phosphatase do in smooth muscle?
Takes the phosphate off the regulatory myosin light chains
causes muscle relaxation
What are the three pumps that contribute to muscle relaxation?
NCX – Primary
SERCA
PMCA (plasma membrane Ca++ ATPase)
What gets rid of the extra Na++ coming into smooth muscle from getting rid of Ca++ from the NCX?
Na+/K+ ATPase
What two neurotransmitters can increase eNOS?
Ach
Bradykinin
What does NO do?
Increase Guanylyl cyclase
Increase cGMP
Increase PKG
PKG inhibits MLCK
Muscle relaxation
What does PKG do to Ca++ channels?
Phosphorylates them causing them to close
Descreases Ca++ = decrease contractions
T/F: Ca++ binding to calmodulin in the endothelium changes the shape, and can increase the activity of eNOS. This will increase the activity of eNOS and argine which will ultimately lead to muscle relaxation
T
What is phosphodiesterase?
Shut down cGMP quickly, causing decrease relaxation
What inhibits phosphodiesterase?
What happens when you inhibit this?
Slidenafil
Increase relaxation
T/F: cGMP is unstable and will fall apart
T
T/F: smooth muscle doesn’t need an AP or calcium for a contraction
T
Ca++ is enough to not have an AP.
When there is no Ca++ something else can manipulate the pathway possibly.
What are long AP in smooth muscles probably from?
L-type channels
What is the only neurotransmittor that can constrict blood brain vessels?
Serotonin
What type of medication can we use for headaches because it constricts blood vessels in the blood brain?
SSRIs
Describe what Alpha 1 receptors do in smooth muscle
G(q) –> increase PLC –> increases IP3 and DAG
In the cardiac muscle: Where does the Ca++ come from?
T-type Ca++ channels (primary)
L-type
SR
In the cardiac muscle: how do you get the SR to release Ca++
Ca++ induced Ca++ release (CICR)
Outside Ca++ has to come in 1st to trigger the release from the SR
T/F: In the cardiac muscle: The SR is well developed
T
In the cardiac muscle: how much Ca++ comes from the SR vs outside?
SR - 80%
Outside 20%
Describe a T-tubules in the cardiac muscle?
Large
Use the store outside calcium until needed for AP
In the cardiac muscle: what is phospholamban
Inhibitory proteins for SERCA. Allows calcium to be in cardiac muscle for a longer = longer contraction
What happens when you give a give a drug that inhibits phospholamban?
Ca++ gets into the SR faster via SERCA = faster contracters = increased HR
In the cardiac muscle: how is Ca++ taken out?
SERCA - 80%
NCX - 15%
PMCA - 5%
In the cardiac muscle: What is calsequestrin?
Found in ALL SR
sequestrins protein - helps take something out of circulation
Helps concentrate Ca++ in SR
What does a beta receptor do in the heart?
G(s)
Increases adenylyl cyclase
inceases cAMP
Increases PKA
Increases contraction and HR
What does a muscarinic receptor do in the heart?
G(I)
inhibits adenylyl cyclase
decrease cAMP
decrease PKA
decrease contraction and HR
What enzyme is found in all cardiac muscle cells?
Adenylyl cyclase
