Smooth And Cardiac Muscles Flashcards
How many times does a heart a day?
I’ve 100K/day
How much ATP is used per day in the heart?
6 kg
The heart muscle is very rich in what organelle in order to supply ATP?
Mitochondria
Describe the cardiac muscle
Single nucleus
Wall of the heart
Branching cells
Striated
In the cardiac muscle cell what type of junctions of the intercalated disc?
Desmosomes and gap junctions
Do cardiac cells have SRs?
Yes
Do cardiac cells have a z disc?
No
Where are the T tubules located in a cardiac muscle cell?
Located at the z disc
How many T tubules does each SR get?
There is only one T tubule per sarcomere which forms a diad.
* instead of a triad, like in the skeletal muscle*
Compared to the T-tubules in the skeletal muscle the diameter of the cardiac muscle T tubule is?
Larger
Go through calcium-induced calcium release for cardiac muscle.
1) Membrane depolarization(via gap junction) and in T tubule invaginations
2) Extracellular Calcium influx via calcium channels (in cardiac muscle cells extra cellular Ca goes inside the cell)
3) Ryanodine receptors at SR (coupled with T-tubule) detect Ca and trigger SR release
4) Ca increase results in increase binding of Troponin C and subsequent contaction
In cardiac muscle is are the striations from?
Intercalated discs
What are some functions of smooth muscle cells?
Helps with vasculature ( helps maintain structures in vessels)
Helps in the intestinal tract (is responsible for peristalsis)
Helps in the ureogentital tract
Describe singe-unit smooth muscle cells.
They are electrically coupled(all connected by gap junctions)
Phasic
Describe multi-unit smooth muscle.
Minimal coupling (not connected by gap junctions)
More innervation
Tonic
Is smooth muscle innervation voluntary or involuntary?
Involuntary=autonomic nervous system
Can also be stimulated by hormones
In smooth muscle innervation what is the end game?
Calcium
Describe the smooth muscle structure.
Diagonal actin/myosin and IM filament organization
No visible striations because not uniform, but still abundant thin filaments
Which has a higher actin:myosin ratio: cardia muscle or smooth muscle?
Smooth muscle
In the smooth muscle what are the sense bodies functionally equivalent to?
Z lines/intercalated discs
Smooth muscle cells do not have T tubules instead they have?
Caveoli- which increases surface area
Go through the smooth muscle contraction.
1) increase calcium
2) calcium binds to calmodulin(CaM) to make Ca/CaM
3) Ca/CaM activates Ca/CaM dependent kinase (CaMK)
4) CaMK phosphorylates and activates myosin light chain kinase (MLCK)
5) MLCK phosphorylates the light chain of myosin
6) Actin/myosin cycling and contraction
What doesn’t smooth muscle have in comparison to cardiac and skeletal muscle when it comes to muscle contraction?
There is no Troponin?
Relaxation is possible via?
Phosphatases
In smooth muscle contraction calcium =
Contraction
In smooth muscle cells Nitric oxide=
Relaxation
Is light chain phosphorylation mandatory for attachment and cycle start up?
Yes, but if the phosphate is lost after it will continue just at a slower rate.
In smooth muscle cells how is a contraction regulated?
1) NTs and hormones to receptor activated calcium channel
2) electrical potential regulated calcium channel
3) NTs and hormones triggering SR release of calcium (RYR) via IP3 pathway
How does smooth muscle cells remove calcium?
SERCA ( not very common)
Na/Ca anti port
Sarcolemma ATPase
True or false: the same ligand can only produce one type of response?
False
