10/29/14 Notes Quiz

Question 1

What percent of cardiac muscle is contractile and non-contractile

Answer 1

99% contractile

1% non-contractile

Question 2

Branching cardiac muscle fibers are interconnected by what?

Answer 2

Intercalated discs

Question 3

What are intercalated discs comprised of?

Answer 3

Desmosomes: hold the cells together mechanically

Gap junctions: permit the spread of electrical current between cells joined together as a functional syncytium.

Question 4

Non-Contractile cardiac muscle properties

Answer 4

• small
• uninucleated
• highly branched
• almost NO sarcomeres
• larger t-tubules
• Intercalated Discs*

Question 5

Contractile Cardiac Muscle properties

Answer 5

• small
• uninucleated
• moves blood from one place to another
• highly branched
• cell to cell connections on terminal not lateral surfaces.
• sarcomeres/striated
• t-tubules: with larger diameter because they hold calcium
• No motor end plate because it is a myogenic muscle.
• no neuromuscular junction

Question 6

Two types of neural inputs to the heart

Answer 6

Fight or flight, rest and digest

Sympathetic and parasympathetic.

Question 7

Does the heart experience hypertrophy or hyperplasia or both?

Answer 7

hypertrophy

Question 8

What acts as an electrical insulator between the atria and the ventricle

Answer 8

AV Valves

Question 9

Nipple like muscular extensions. Extension of contractile cardiac muscle

Answer 9

Papillary muscle

Question 10

What attaches from the AV Cusp to the Papillary muscle?

Answer 10

Chordea Tendinae: prevent retrograde opening of the AV Valves

Question 11

D-loop/S-loop

Answer 11

D-loop: right handed loop of the embryo heart grows at a fast rate, lots of pressure variances, as the embryo grows, the d-loop flops over on itself and creates an s-loop. Blood flows in and out of the base. The apex is at the bottom.

Question 12

Bicuspid valve

Answer 12

easier to keep closed

• has to withstand more pressure than tricuspid, due to more pressure on the left than the right side.
• higher pressure opens
• mitral: popes hat

Question 13

Tricuspid valve

Answer 13

easier to open

Question 14

Semilunar Valves

Answer 14

• prevent retrograde flow
• saloon door valves: opened by blood as it passes by
• no chordea tendone. They would be in the way of flow on the arterial side.

Question 15

Where are cardiac muscle cells found?

Answer 15

Heart…pssh. The aorta is not the heart.

Question 16

Do atrium and ventricle contract at the same time?

Answer 16

Atriums contract and then the ventricles contract. Left and right sides are controlled by the same stimulator. Atriums contract top to bottom and ventricles bottom to top.

Question 17

1% non-contractile cardiac muscle consists of?

Answer 17

Upper right region of the right atrium is the beginning.

1. Sino-Atrial Node SA node. This sends the initial signal through the internodal pathway to the
2. Atrio-Ventricular Node.