Test 4 Cardio

Question 1

Cardiac myocytes (Cardiac Muscle) have a high number of what? This allows for production of what without fatigue of the muscle?

Answer 1

• High Number of Mitochondria

- Allows continuous high-level aerobic production of Adenosine Tri-Phosphate (ATP)

Question 2

What structural aspects of Cardiac Muscle allow for Rapid Synchronous spread of action potential between cells?

Answer 2

• Fewer and Larger T-Tubules

- Intercalated Discs

Question 3

Cardiac muscle relies on what action in order to convert electrical signal to muscle contraction?

Answer 3

Rapid release and re-uptake

of Intracellular Calcium stores

Question 4

What structure in the heart initiates action potential? What is the intrinsic rate of this structure?

Answer 4

Sinoatrial Node (SA) -60-100bpm

Question 5

What structure in the heart is responsible for delaying the electrical signal? What is the intrinsic rate of this structure?

Answer 5

Atrioventricular Node (AV) -40-60bpm

Question 6

Sympathetic Nervous stimulation of the heart will cause what to occur with the heart?

Answer 6

Increase SA Node Rate

Increase Force of Contraction

Question 7

Parasympathetic Nervous stimulation of the heart will cause what to occur with the heart?

Answer 7

Decrease SA Node Rate

Decrease Force of Contraction

Question 8

What is defined by; Autonomous process that results in the organized, sequential, contraction and relaxation of the chambers of the heart?

Answer 8

Cardiac Cycle

Question 9

When looking at an ECG the P-wave represents what?

Answer 9

Atrial Depolarization

Question 10

What portion of an ECG represents ventricular depolarization?

Answer 10

QRS-Complex

Question 11

The only repolarization wave to be seen on an ECG is called what? And what portion of the heart is repolarizing?

Answer 11

T-Wave

Ventricular Repolarization

Question 12

What is the name of the Membrane Channels that Muscle Contraction relies on?

Answer 12

Voltage-Dependent Calcium Channels (VDCCs)

Question 13

What type of Voltage-Dependent Calcium Channel (VDCC) is the predominant one found in Cardiac cells?

Answer 13

L-Type Channel

Question 14

What subunit (Protein) of the L-Type Voltage-Dependent Calcium Channel (VDCC) forms the pore?

Answer 14

Alpha1 subunit w/6 trans-membrane Alpha-Helices

Open and Close upon Voltage Changes

Question 15

What is the function of the Disulfide-linked Alpha2-Gamma subunit of the L-Type VDCC?

Answer 15

• Anchors the Alpha1 subunit to cell membrane

- Augments response to Voltage Changes

Question 16

What subunit of the L-Type VDCC catalyzes

ATP + GMP –> ADP + GDP?

Answer 16

Beta Subunit (Guanylate Kinase)

Question 17

What affect does the conversion of GMP to GDP have on the L-Type VDCC?

Answer 17

Regulates Alpha1 subunit (pore) voltage sensitivity

–(i.e. Beta subunit activity allows smaller depolarization’s and channel opening)–

Question 18

What provides the initial stimulus causing the L-Type VDCC to respond?

Answer 18

Action Potential of SA Node, AV Node, or Purkinje Fibers

Question 19

How does the L-Type VDCC respond to the action potential from either the SA Node, AV Node, or Purkinje Fibers?

Answer 19

Opens by depolarization of the cell membrane

Question 20

What affect does Epinephrine (Adrenaline) and Dopamine have on the heart?

Answer 20

Increase Heart Rate
and/or
Increase Stroke Volume