MCAT Cardiovascular Sys.

Question 1

Describe the 2-pump system of the heart.

Answer 1

The right side of the heart received deoxygenated blood from the body and sends it to the lungs to get oxygenated via the pulmonary valve.

The left side of the heart accepts oxygenated blood from the lungs and sends it throughout the body via aortic valve.

Question 2

Describe the function of the right atria and ventricles and the left atria and ventricles.

Answer 2

Right atria accept deoxygenated blood from the inferior vena cava and superior vena cava and pumps blood to right ventricle which than sends it to lungs.

Left atria accepts oxygenated blood via the pulmonary veins and sends it out to the body via the aortic valve.

Question 3

Atrioventricular valves v. Semilunar valves

Answer 3

Atrioventricular valves separate the atria from the ventricles.

Semilunar valves separate the ventricles from the vasculature.

Question 4

Tricuspid valve v. Bicuspid valve (mitral valve)

Answer 4

Tricuspid valve separates the right atrium and right ventricle.

Bicuspid valve separates the left atrium from the left ventricle.

Question 5

Pulmonary valve v. Aortic valve

Answer 5

Pulmonary valve - where right ventricle sends deoxygenated blood to the lungs.

Aortic valve- where left ventricle sends oxygenated blood to the lungs.

Question 6

Which side of the heart is more muscular?

Answer 6

The left side of the heart because it needs to maintain blood pressure as the blood moves throughout the body.

Ventricles are more muscular than atrium.

Question 7

How is rhythmic contraction of the heart controlled?

Answer 7

Through 4 excitable structures.

SV node to AV node to bundle of His (AV bundle) to Purkinje fibers.

The signal starts at the SV node which is located in the right atrium. Firing rate of the SV node sets the firing rate at 60-100 BPM.

Question 8

Atrial kick

Answer 8

The additional contraction force of the atrium that allows movement of more blood into the ventricles.

Question 9

How does cardiac cells maintain simultaneous rhythmic contraction?

Answer 9

Through intercalated disks which are connected to each other through gap junctions.

Question 10

Vagus nerve

Answer 10

The nerve by which the parasympathetic NS controls the contraction of the heart.

Question 11

Systole v. Diastole

Answer 11

Systole is ventricular contraction (atrium contracts) and diastole is ventricular relaxation (atrium contracts filling blood into ventricles)

Question 12

How to calculate cardiac output?

Answer 12

By multiplying the heart rate and the stroke volume (volume of blood pushed out with every beat).

Question 13

What are the three major types of vasculatures?

Answer 13

Veins, arteries, and capillaries

Question 14

Arteries

Answer 14

Moves oxygenated blood throughout the body.

Exceptions are pulmonary arteries and umbilical arteries (carries deoxygenated blood).

Question 15

Describe the flow of blood throughout the body?

Answer 15

Arteries carry oxygenated blood. Once it reaches tissues it branches off into arterioles and then into capillaries.

Venules then lead into veins which empties deoxygenated blood into IVC and SVC.

Question 16

Does arteries or veins have more smooth muscle?

Answer 16

Arteries has smoother muscle. Due to the need to push blood throughout the body.

Question 17

Describe the structure of capillaries?

Answer 17

Single endothelial layer to allow easy diffusion of gases, nutrients, and wastes.

Where gas exchange occurs.

Question 18

Describe the structure of veins?

Answer 18

Carries deoxygenated blood back to the heart.

Except the pulmonary veins and umbilical veins which carry oxygenated blood

Question 19

Portal systems

Answer 19

Systems in which blood must past through two capillary beds.

• Hepatic portal system - passed through capillary beds of gut and liver.
• Renal portal system - passed through glomerulus and nephrons.
• Hypophyseal portal system - passed through hypothalamus and anterior pituitary.

Question 20

What are the components of blood?

Answer 20

Plasma - liquid portion

Cellular portion - contains erythrocytes, leukocytes, and platelets.

Serum - plasma with clotting factors removed.

Question 21

Describe the shape and function and erythrocytes (red blood cells)

Answer 21

Contains hemoglobin which has 4 subunits each with a heme prosthetic group that can each hold one O2 molecular (therefore a total of 4 O2 molecules).

Has a biconcave shape which increases their surface area for O2 attachment and easier movement into the capillaries.

Question 22

RBCs doesn’t have organelles. Why?

Answer 22

So, they can have more room for oxygen therefore they rely of glycolysis for ATP production.

Question 23

What are the two antigen types of the surface of the RBCs?

Answer 23

ABO and Rh factor

A and B alleles are dominant to O allele and codominant to each other. O is the recessive genotype.

Question 24

What will occur to someone who receives the wrong blood type?

Answer 24

Hemolysis

Question 25

Describe the unique characteristics of ABO blood types

Answer 25

People with O blood type are universal donors but can only receive other O blood type.

People with AB blood type are universal recipients including O type.

Question 26

Rh factor

Answer 26

Surface protein named D.

Can be Rh+ or Rh-

Rh+ is autosomal dominant. Only needs one allele present.

Can be expressed with ABO antigens as a + or -.

Question 27

Hypertension

Answer 27

High blood pressure

Can damage blood vessels.

Sphygmomanometer is an instrument that measures blood pressure.

Question 28

How is blood pressure represented?

Answer 28

As a ratio:
Systolic/ Diastolic

Question 29

How to calculate the peripheral resistance?

Answer 29

Multiplying the cardiac output x total peripheral resistance.

Larger the cross-sectional area of the blood vessel, less the pressure.

Question 30

Role of baroreceptors

Answer 30

Receptors located in the walls of the blood vessels and measures blood pressure.

When a drop in B.P. happens ADH or aldosterone is released.

Question 31

How does nutrient, waste, and gas exchange happen between cardiovascular system and tissues?

Answer 31

Simple diffusion

Question 32

How does the conformation of the heme prosthetic group changes when O2 binds?

Answer 32

Changes conformation that increases the affinity for the next oxygen.

Question 33

Role of carbonic anhydrase

Answer 33

An enzyme that serves the role of converting CO2 into bicarbonate ion so it can soluble in blood. Once it’s in the lungs the reaction is reversed and we breath out CO2.

Question 34

Describe the Bohr effect

Answer 34

Describes increased oxygen delivery to the tissues during exercises.

As we exercise CO2 builds up in our tissues shifting bicarbonate buffer system to the right. H+ decreases hemoglobin’s affinity for oxygen allowing more oxygen delivery to the tissues and a shift to the right on the oxyhemoglobin curve.

Question 35

Hydrostatic pressure

Answer 35

The pressure exerted by blood against blood vessel walls. Pushes fluid out into the interstitium.

Question 36

Oncotic pressure

Answer 36

The sucking pressure of water caused by increased presence of solutes in blood.

Question 37

What allows the flow of blood between blood vessels and tissues?

Answer 37

Pressure differentials.

Question 38

Describe the process of clots are formed?

Answer 38

1. Platelets sense collagen and tissue factor.
2. Platelets sense exposed collagen and begins to aggregate.
3. Liver detects tissue factor and secretes coagulation factors which starts an activation cascade.
   
   • Thromboplastin converts prothrombin to thrombin.
     - Thrombin converts fibrinogen to fibrin.
     - fibrin creates a cross- link meshwork creating a clot.
4. Clot is broken down by plasmin which is synthesized by plasminogen.