Smooth And Cardiac Muscles

Question 1

How many times does a heart a day?

Answer 1

I’ve 100K/day

Question 2

How much ATP is used per day in the heart?

Answer 2

6 kg

Question 3

The heart muscle is very rich in what organelle in order to supply ATP?

Answer 3

Mitochondria

Question 4

Describe the cardiac muscle

Answer 4

Single nucleus
Wall of the heart
Branching cells
Striated

Question 5

In the cardiac muscle cell what type of junctions of the intercalated disc?

Answer 5

Desmosomes and gap junctions

Question 6

Do cardiac cells have SRs?

Answer 6

Yes

Question 7

Do cardiac cells have a z disc?

Answer 7

No

Question 8

Where are the T tubules located in a cardiac muscle cell?

Answer 8

Located at the z disc

Question 9

How many T tubules does each SR get?

Answer 9

There is only one T tubule per sarcomere which forms a diad.

* instead of a triad, like in the skeletal muscle*

Question 10

Compared to the T-tubules in the skeletal muscle the diameter of the cardiac muscle T tubule is?

Answer 10

Larger

Question 11

Go through calcium-induced calcium release for cardiac muscle.

Answer 11

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

Question 12

In cardiac muscle is are the striations from?

Answer 12

Intercalated discs

Question 13

What are some functions of smooth muscle cells?

Answer 13

Helps with vasculature ( helps maintain structures in vessels)
Helps in the intestinal tract (is responsible for peristalsis)
Helps in the ureogentital tract

Question 14

Describe singe-unit smooth muscle cells.

Answer 14

They are electrically coupled(all connected by gap junctions)
Phasic

Question 15

Describe multi-unit smooth muscle.

Answer 15

Minimal coupling (not connected by gap junctions)
More innervation
Tonic

Question 16

Is smooth muscle innervation voluntary or involuntary?

Answer 16

Involuntary=autonomic nervous system

Can also be stimulated by hormones

Question 17

In smooth muscle innervation what is the end game?

Answer 17

Calcium

Question 18

Describe the smooth muscle structure.

Answer 18

Diagonal actin/myosin and IM filament organization

No visible striations because not uniform, but still abundant thin filaments

Question 19

Which has a higher actin:myosin ratio: cardia muscle or smooth muscle?

Answer 19

Smooth muscle

Question 20

In the smooth muscle what are the sense bodies functionally equivalent to?

Answer 20

Z lines/intercalated discs

Question 21

Smooth muscle cells do not have T tubules instead they have?

Answer 21

Caveoli- which increases surface area

Question 22

Go through the smooth muscle contraction.

Answer 22

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

Question 23

What doesn’t smooth muscle have in comparison to cardiac and skeletal muscle when it comes to muscle contraction?

Answer 23

There is no Troponin?

Question 24

Relaxation is possible via?

Answer 24

Phosphatases

Question 25

In smooth muscle contraction calcium =

Answer 25

Contraction

Question 26

In smooth muscle cells Nitric oxide=

Answer 26

Relaxation

Question 27

Is light chain phosphorylation mandatory for attachment and cycle start up?

Answer 27

Yes, but if the phosphate is lost after it will continue just at a slower rate.

Question 28

In smooth muscle cells how is a contraction regulated?

Answer 28

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

Question 29

How does smooth muscle cells remove calcium?

Answer 29

SERCA ( not very common)
Na/Ca anti port
Sarcolemma ATPase

Question 30

True or false: the same ligand can only produce one type of response?

Answer 30

False