Test 3 - 10/11 Lecture Flashcards
If your muscle is overstretched you will not get ______ when it is contracted
optimal contractile force
the Length-tension relationship graph looks at
how well the muscle is being stretched out
If a muscle is not stretched out at all it wont be able to ______ because the myosin filaments have a fixed width
shorten much
The measurement of force of contraction in a muscle that is caused by an action potential is called
Active tension
The force applied by pulling on tendons, stretching the sarcomeres causing the muscle to stretch out.
Tension/stretch not caused by an AP.
Passive tension
Total tension
the measure of an outside force stretching out a muscle + the force of contraction caused by an AP
How is active tension calculated
total tension - passive tension
How can we measure passive tension?
Force/Pressure transducer on one end that is able to measure the amount of tension in the muscle as a weight is hanging on the other side stretching a muscle
When looking at the Load/Contraction Velocity Diagram: if we have a lighter load the velocity of contraction is _____
Higher
Load/contraction velocity: Increased load = _______ muscle contraction speed
decreased
The load of the muscle and the velocity at which it contracts is
inversely related
If the heart is pumping against a high afterload it takes the heart _____
longer to eject the blood
If the strain (load) on the heart is difficult for the heart to overcome we would expect to see
bradycardia/arrythmias
Quantal summation
Recruitment mechanism where more motor units are recruited to produce more and more force
Quantal summation is _____.
It is managed by ______ of nervous system.
number of motor units recruited.
Voltage.
(higher voltage = more motor neurons helping out)
temporal summation
Force generation in comparison to rate of stimulation (given in HZ).
Strength of contraction increases with increasing frequency of stimulation. The muscle is not fully relaxed and the contraction strength becomes additive.
The ion responsible for temporal summation is ______ what is happening with this ion?
Calcium, it is coming out of the sarcoplasmic reticulum faster than it can be returned. Increasing ICF calcium resulting in stronger contraction.
Temporal summation becomes additive at approximately _____
10-12 Hz
Tetany is produced when a stimulation of ______ is applied. Why does this happen?
40 Hz
Saturation of Ca
Atrophy typically occurs in the ____ first and then the ______ if muscles are not in use for a long period of time
myofibrils; muscle fibers
Skeletal muscles get bigger by a process called _______. The growth is because there is an increase in _______
Hypertrophy; the number of myofibrils present.
What happens long term to the vasculature in a muscle with hypertrophy?
longer term the vascular bed that is developed in the muscle also increases the size.
Muscle Hyperplasia
Exercising a ton for a long period of time can generate some muscle fiber (cells)
(this takes a very long time)
Any drug that causes proliferation of muscle cells would put the patient at a higher risk of
cancer
Smooth muscle makes up about ______ of body mass
10%
We have smooth muscle ______. It will look different depending on the role it plays
Lungs, intestines, blood vessels.
All over the place
What are some ways that smooth muscles vary from skeletal muscles?
-lots of variation (depending on the role they have)
-more efficient (highly specialized)
-Slower cross-bridge cycling
-“latch” mechanism
-stronger
In ______ it takes longer for the myosin head to release from the actin filiments
smooth muscle
If smooth muscle and skeletal muscle were championship boxers which would be the better pound for pound fighter?
Smooth muscle is stronger (per gram muscle)
Latch Mechanism in Smooth Muscle
once contracted smooth muscle can maintain the force of contraction without the need for cross-bridge cycling that is seen in skeletal muscle.
cells in smooth muscle are ______ in size cpmpared to the cells in skeletal muscle.
They are connected by _____, _____, or to neighboring cells vis _____
way smaller
Fascia, connective tissue, gap junctions
Actin : Myosin ratio skeletal muscle
2:1
Actin : Myosin ratio of smooth muscle (range)
10-20 : 1
In smooth muscle we have _____ actin compared to myosin
more
The equivalent of the Z disk on a smooth muscle is the
Dense bodies
______ anchor the actin in place on smooth muscle
Dense bodies
The sarcoplasmic reticulum in smooth muscle compared to skeletal muscle is ____
less developed
Most smooth muscle is reliant on an outside source of to contract
Ca
How does outside Ca get into smooth muscles?
Leak in
voltage gated
ligand gate
If someone has a Ca level of 0 what could this cause (when thinking about smooth muscles). Why?
no BP. Bc the heart and vascular smooth muscle are both dependent on Ca to contract
Visceral/unitary smooth muscles are composed of ______ and are connected by _____
composed of sheets of spindle-shaped cells in close contact with one another
connected by gap junctions
The linkage of neighboring cells on a smooth muscle is achieved by the
Dense bodies
A patient that has a calcium level that is near zero has a low blood pressure. Why?
The smooth muscle is dependent on outside calcium to contract. If your blood vessels that are lined with smooth muscle cannot contract you have a problem. (The heart would also be quite unhappy)
Multi-unit smooth muscle
Smooth muscle that is separated from one another and not connected by gap junctions. These behave more like individual cells.
Where would we find visceral smooth muscle?
Hollow organs (ex. small intestine)
What would be an example of multi-unit smooth muscle
ciliary smooth muscle in the eye
multi-unit smooth muscle is good for
fine tuned motor movements
A smooth muscle that we have conscious control of
Esophagus (hybrid skeletal muscle and visceral smooth muscle)
If smooth muscle is involved in a process that requires delicate manipulation we would anticipate that it would be ______ smooth muscle
multi-unit
Vascular smooth muscle is what type of smooth muscle?
Visceral smooth muscle
Arterial blood vessel layers (exterior to interior)
Adventitia (connective tissue)
Visceral smooth muscle
Endothelial cells
A vessel that has only endothelium and no smooth muscle is your
capillaries
Alternate (older) names to blood vessel layers (inside to out)
Tunica Intima
Tunica Media
Tunica Adventitia/Externa
The adventitia of arterial blood vessels creates
support/structure
The endothelial layer and the vascular smooth muscle in blood vessels can communicate with each other via
neurotransmitters or gasses (NO)
There is a differing layout of actin and myosin in smooth muscle when compared to skeletal muscle. Which contraction would cause a larger percent change in the size of the muscle?
The smooth muscle shortens by about 50% it’s resting length.
The neurotransmitter for skeletal muscle is always
ACh
How do the mACh-R react on the smooth muscles of capillaries vs Sm intestines?
Capillaries: relax
Sm intestines: contract
Actin in smooth muscle is not _____ by tropomyosin like in skeletal muscle
hidden/inhibited
Myosin light chain kinase performs what action in smooth muscle
Phosphorylates the regulatory myosin light head
Smooth muscle: Myosin light chain kinase activity is determined by
ICF calcium levels (and calmodulin)
Smooth muscle: When we have free intracellular Ca that will bind with ______ and activate _____ which will in turn take ______ leading to contraction.
Calmodulin
MLCK
Take inactive myosin and phosphorylate it
Smooth muscle: Where do we get the Ca from?
SR (not a lot, usually underdeveloped)
Outside of cell
-Leak channel
-Voltage gated (L type Ca channel)
-Ligand gated
An important voltage gated ion channel in smooth muscle is the
L type calcium channel (slow)
Active myosin in smooth muscle is deactivated by what enzyme?
Myosin light chain phosphatase (myosin phosphatase)
Decreasing ______ would decrease the activation of myosin
Ca
3 places where calcium can be removed from the ICF
1- SERCA pump stores in SR
2- Plasma Membrane Calcium ATPase (PMCA) pump
3- Sodium calcium exchanger (most efficient)
What is the ion flow of the sodium calcium exchanger?
3 sodium allowed in for 1 calcium to be removed from the ICF
Following removal of Ca via the Ca/Na exchanger. How would the additional Na be removed?
Na/K/ATPase
When looking at a vascular smooth muscle cell If there is an AP, ____ enters via ____. Once in the cell it combines with ____ which activates _____ which phosphorylates to _____ causing an increase in the cycling rate of the myosin head leading to contraction
Ca
Ca channels (slow ca channels)
Calmodulin
MLCK
Myosin-LC PO4
Nitrates increase the amount of _____.
cGMP
cGMP activates _____ that then _____ the activity of MLCK
Protein Kinase G; reduces (resulting in less smooth muscle contraction)
How does protein kinase G inhibit the action of MLCK
It phosphorylates MLCK (reducing the amount of phosphates stuck to the myosin heads) AND phosphorylates Calcium entry channel.
endogenous nitrates in smooth muscle comes from
Endothelial cells (eNOS)
What are the 5 steps involved in endothelial cell production of nitric oxide
1- GPCR activation of endothelial cell via ACh or bradykinin
2- Calcium is released from the the ER of the endothelial cell
3- Calcium combines with Calmodulin
4- Calmodulin increases the activity of eNOS
5- eNOS acts on L arginine to form Nitric oxide
Once Nitric oxide is formed in the Endothelial cell how does it effect vascular relaxation. 5 steps
1- The gas diffuses from endothelium to vascular smooth muscle
2- It increases the activity of Soluble Guanyl Cyclase
3- guanyl cyclase transforms GTP to cGMP
4- cGMP activates PKG
5- PKG inhibits MLCK and calcium entry.
The compound that is responsible for enhanced breakdown of cGMP is
(PDE) Phosphodiesterase
If we give a phosphodiesterase inhibitor this will result in
More cGMP that will increase amt of PKG which will phosphorylate MLCK causing increased vascular relaxation.
An example of a phosphodiesterase inhibitor is
Sildenafil
Smooth muscle: Explain alpha 1 agonist activity on the Gq pathway (focus on IP3)
The Gq GPCR activates Phospholipase C. Phospholipase C removes IP3 and DAG from the cell wall. IP3 frees calcium from the SR. Calcium > Calmodulin > increase MLCK activity > more “ready” myosin and smooth muscle contraction
The only neurotransmitter that can constrict brain blood vessels is
Serotonin (it follows the same steps as the Gq pathway)
SSRI’s can be useful for headaches because they
increase the tone in the blood vessels
Smooth muscles can _____ independent of action potentials
contract
Smooth muscle: When the membrane potential is changing all on its own this is thought of as. Example of where we would see this?
pacemaker activity
Small intestines
In the heart the calcium required for contraction comes from mostly _____ and is supplemented by ______
Sarcoplasmic Reticulum (SR) 80%
ECF calcium 20%
In the heart, before calcium is released from the SR we must have ______. This is called ____
“Trigger calcium” come from the ECF
CICR (calcium induced calcium release)
The T-type calcium and L-type calcium channels in the heart are triggered to open by _____
A sodium induced action potential in the heart muscle (T type is faster and opens first. then L type)
The T tubules of the heart have a high density of
Ca
80% of Ca removal in the heart cell is done via ______. The remaining 20% is done via Ca channels, heavy lifting is done by the _____ and secondary is the ____
SERCA pump
Na/Ca channel (3 Na in, 1 Ca out)
PMCA (plasma membrane calcium ATPase)
What is phospholamban in the heart
an inhibitor that alters SERCA activity that is unique to the heart
Calsequestrin
calcium-binding protein within the sarcoplasmic reticulum which aids in storage of intracellular Ca2+
An inhibitor of phospholamban would (3)
1- Allow calcium storage in the SR to happen quickly
2- Shorten the contraction of the heart
3- Allow for the heart to be prepared for the next contraction faster than normal (causing an increased HR)
In the heart, more adrenergic activity will lead to ______ heart rate, while more cholinergic activity will lead to ______ heart rate
increased
decreased
Beta 1 in the heart is G stimulatory. What does this mean and what effect does it have?
G stimulatory means it activates Adenyl Cyclase increasing circulating cAMP. cAMP activates PKA that increases the Strength and Speed of contraction.
mAChR in the heart is G inhibitory. What does this mean and what effect does it have?
G inhibitory means that it inhibits the activity of adenyl cyclase, reducing circulating cAMP. A decrease in cAMP decreases PKA activity and therefore slows down the heart and decreases the strength of contraction.
