Cardiology-Pharmacology

Question 1

How many liters of blood are in the body and where is the majority of it located?

Answer 1

5 liters of blood and the majority is in the venous system

Question 2

What are the properties of cardiac muscle?

Answer 2

Contractility (Inotropic)
Extensibility
Rhythmicity (Chronotropic)
Automaticity
Conductivity (Dromotropic)
Irritiability

Question 3

Define Phase 0

Answer 3

Depolarization occurs because sodium is rushing into the cell and forcing potassium out. This shows up as the P-Wave and QRS Complex on an ECG.

Question 4

Define Phase 1

Answer 4

Repolarization begins as sodium starts exiting the cell and calcium starts entering the cell. On an ECG this shows up as the T-Wave.

Question 5

Define Phase 2

Answer 5

Repolarization is continuing and the voltage plateau’s and maintains itself for a bit. Calcium is entering the cell and helping it to maintain its energy. Sodium is being pushed out and potassium is being pulled in.

Question 6

Define Phase 3

Answer 6

Phase 3 begins when enough Calcium has entered the cell to change the normal balance of electrical charges to a point which deactivates the Calcium channel gates. Ca++ flow into the cell stops. At this point the sodium/potassium pumps and Calcium pumps move enough Na+ and Ca++ out of the cell and begin the cells return to phase 4.

Question 7

Define Phase 4

Answer 7

This is the resting phase of the cell. Sodium is under a great deal of pressure to enter the cell to balance electrostatic and concentration gradients while potassium concentration has balanced itself. Calcium is also waiting/trying to balance it’s concentration. The cell is waiting for something (electricity) to pull the trigger.

Question 8

What does Calcium do to muscles?

Answer 8

Calcium causes all muscles, including cardiac to contract. It also has a positive charge.

Question 9

What is the difference between a fast acting and slow acting miocyte (cell?)?

Answer 9

The difference is how fast the calcium is leaking into the cell. And in turn causes the cell to build up to threshold.

Example: SA/AV Node is fast.
Purkinje fibers and Bundle of His is slow.

Question 10

What is the absolute refractory period?

Answer 10

This is the area above the threshold. In this area the cell cannot accept another charge until the voltage drops below the threshold.

Question 11

What is the relative refractory period?

Answer 11

This is the area below the threshold. In the area the cell can accept a charge, even though it is not completely through the cycle yet.

Question 12

What are the stages of blood vessel contraction?

Answer 12

1) Calcium enters the cell from SR and extracellular region
2) Calcium binds with a protein (Calmodulin)
3) Calmodulin then activates kinase enzyme
4) Kinase enzyme phosphoralates (ATP) to myosin filaments causing contraction

Question 13

What is the formula for Mean Arterial Pressure (MAP)?

Answer 13

Systolic Blood Pressure + 2(Diastolic Blood Pressure)/3=MAP

Question 14

What is the formula for Cardiac Output?

Answer 14

CO= Heart Rate x Stroke Volume

Question 15

What is Stroke Volume?

Answer 15

The amount of blood ejected with one pump

Question 16

Define pre-load.

Answer 16

The amount of tension (stretch) applied to the cardiac muscle prior to contraction. Also known as end diastolic volume.

Question 17

What is Starlings Law?

Answer 17

The force of ventricular contraction is proportional to muscle fiber length (up to a point). As the fiber length increase there is a corresponding increase in contractile force.

• If you want more contractile force then increase the fluid (pre-load)

Question 18

Define afterload

Answer 18

The pressure the heart must overcome to eject blood from the heart. Also called SVR (systemic vascular resistance).

Question 19

What are the key points of Heart Rate?

Answer 19

The sum of the pacemaker rate, Autonomic Nervous system, slow cardiac action potential.
Balanced by the Autonomic nervous system
HR increased by the beta-1 receptor, the SA node
HR decreased by the parasympathetic nervous system through muscarinic receptors in the SA and AV node, via the Vagus nerve

Question 20

How does the body maintain MAP?

Answer 20

Baroreceptors are feedback mechanisms which help maintain MAP in response to quick postural movements of the body. Baroreceptors are located in the Aortic arch and the Carotid sinus. Also the body maintains MAP through ADH release and RAAS (Renin Angiotensin Aldosterone System).

Question 21

How does Anti-Diuretic Hormone (ADH) help maintain MAP?

Answer 21

ADH is released by the posterior pituitary gland when the body is markedly hypotensive. ADH causes some vasoconstriction, but mainly causes fluid retention in the body.

Question 22

What are the key points to remember for RAAS?

Answer 22

Aldosterone causes the kidney to hold onto Na and H2O increasing fluid retention
Renin is a chemical released by the kidney
A negative feedback loop occurs in response to a decreased renal perfusion

Question 23

What causes renin to be released?

Answer 23

Beta-1 stimulation
A decrease in renal perfusion factors
Decreased blood pressure
Decreased volume
Hyponatremia

Question 24

What happens when renin is released?

Answer 24

Renin binds with angiotensinogin (protein) and converts to angiotensin 1

Question 25

What is angiotensin 1?

Answer 25

An inactive biochemical

Question 26

What is angiotensin 2 and what does it do?

Answer 26

It is a highly active biochemical. It causes systemic vasoconstriction, releases aldosterone, and causes fluid retention.

Question 27

How do we get from angiotensin 1 to angiotensin 2?

Answer 27

ACE (Angiotensin Converting Enzyme) converts angiotensin 1 into angiotensin 2.

Question 28

What are the three killer B’s?

Answer 28

Bradycardia
Bronchoconstriction
Bronchoria

Question 29

What are the normal pacemaker sites in the heart? And are they slow or fast acting cells?

Answer 29

SA Node, AV Node and they are slow acting cells.