Cardiovascular Physiology 14

Question 1

What follows depolarization of the cardiac myocytes?

Answer 1

The contraction of the cardiac myocytes

Question 2

What is the shaped of Cardiac Myocytes?

Answer 2

Branched or Y shaped

Question 3

What are Cardiac Myocytes joined together by?

Answer 3

Intercalated discs

Question 4

What occurs at the intercalated discs of cardiac myocytes?

Answer 4

Cardiac myocytes are extensively intertwined

Question 5

What are found at the intercalated discs of myocytes?

Answer 5

Gap junctions and desmosomes

Question 6

What is the Sarcolemma?

Answer 6

The plasma membrane of a cardiac myocyte

Question 7

What are the mitochondria of cardiac myocytes important for?

Answer 7

Supplying the myocyte with ATP

Question 8

What is the Sarcoplasmic Reticulum?

Answer 8

A special type of smooth endoplasmic reticulum which stores and pumps calcium ions

Question 9

What does the Sarcoplasmic Reticulum in cardiac myocytes do?

Answer 9

Stores and releases calcium when the muscle cell is stimulated

Question 10

What are Cardiac Myocytes made up of?

Answer 10

Myofibrils

Question 11

What do Myofibrils run the length of?

Answer 11

The length of the branched muscle cell

Question 12

What is each Myofibril made up of?

Answer 12

Sarcomeres

Question 13

What are Sarcomeres?

Answer 13

The contractile unit of muscle

Question 14

What do Sarcomeres contain?

Answer 14

The protein filaments actin and myosin

Question 15

What gives cardiac muscle cells its striated appearance?

Answer 15

The orderly arrangement of actin and myosin

Question 16

What are T-tubules?

Answer 16

Invaginated of the Sarcolemma

Question 17

What do the T-tubules surround?

Answer 17

The myofibrils

Question 18

What do T-tubules do in Cardiac Myocytes?

Answer 18

They transmit action potentials propagated along the surface membrane to the interior of the muscle fiber

Question 19

What is the lumen of the T-tubule continuous with?

Answer 19

The extracellular fluid in the muscle fiber

Question 20

What does the T-tubule lie in close proximity to?

Answer 20

The sarcoplasmic reticulum

Question 21

What kind of channels do T-tubules have a lot of?

Answer 21

L-type calcium channels

Question 22

What controls contraction of the cardiac muscle?

Answer 22

Calcium ions

Question 23

What are normal concentrations of calcium inside and outside the cell?

Answer 23

Calcium is usually found in low concentrations inside the cell and high concentrations outside the cell

Question 24

When do extracellular calcium ions enter the cytoplasm of a cardiac myocyte?

Answer 24

During the plateau phase of an action potential through the the L-type calcium channels

Question 25

What does the Calcium that enters the cell during the plateau phase of a cardiac muscle action potential through the L-type channels do?

Answer 25

Binds to Ryanodine receptors on the sarcoplasmic reticulum

Question 26

What happens when calcium binds to Ryanodine receptors in a cardiac muscle cell?

Answer 26

The channel in the ryanodine receptor opens allowing the release of calcium from the sarcoplasmic reticulum into the cytoplasm

Question 27

What is Calcium-dependant calcium release?

Answer 27

Calcium causing it own release from the sarcoplasmic reticulum in cardiac muscle cells

Question 28

What is the source of about 95% of calcium in the cytoplasm in cardiac muscle cells?

Answer 28

The sarcoplasmic reticulum