Test 3 - 10/11 Lecture Flashcards by Amanda M.

If your muscle is overstretched you will not get ______ when it is contracted

optimal contractile force

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the Length-tension relationship graph looks at

how well the muscle is being stretched out

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If a muscle is not stretched out at all it wont be able to ______ because the myosin filaments have a fixed width

shorten much

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The measurement of force of contraction in a muscle that is caused by an action potential is called

Active tension

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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

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Total tension

the measure of an outside force stretching out a muscle + the force of contraction caused by an AP

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How is active tension calculated

total tension - passive tension

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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

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When looking at the Load/Contraction Velocity Diagram: if we have a lighter load the velocity of contraction is _____

Higher

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Load/contraction velocity: Increased load = _______ muscle contraction speed

decreased

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The load of the muscle and the velocity at which it contracts is

inversely related

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If the heart is pumping against a high afterload it takes the heart _____

longer to eject the blood

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If the strain (load) on the heart is difficult for the heart to overcome we would expect to see

bradycardia/arrythmias

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Quantal summation

Recruitment mechanism where more motor units are recruited to produce more and more force

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Quantal summation is _____.
It is managed by ______ of nervous system.

number of motor units recruited.
Voltage.
(higher voltage = more motor neurons helping out)

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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.

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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.

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Temporal summation becomes additive at approximately _____

10-12 Hz

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Tetany is produced when a stimulation of ______ is applied. Why does this happen?

40 Hz
Saturation of Ca

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Atrophy typically occurs in the ____ first and then the ______ if muscles are not in use for a long period of time

myofibrils; muscle fibers

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Skeletal muscles get bigger by a process called _______. The growth is because there is an increase in _______

Hypertrophy; the number of myofibrils present.

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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.

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Muscle Hyperplasia

Exercising a ton for a long period of time can generate some muscle fiber (cells)

(this takes a very long time)

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Any drug that causes proliferation of muscle cells would put the patient at a higher risk of

cancer

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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

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

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

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

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.