🫀 | Chapter 13: Blood, Heart, and Circulation

What are the three major functions of the circulatory system?

Transportation (gases, nutrients, wastes), regulation (temperature & hormones), and protection (clotting & immunity)

What are the three main components of the circulatory system?

Heart, blood vessels, and blood

What is hematocrit?

The percentage of blood volume made up of formed elements (~45%)

What are the two main components of blood?

Plasma (55%) and formed elements (45%)

What is plasma?

The liquid portion of blood that transports solutes, proteins, and cells

Which plasma protein is most important for maintaining blood volume and pressure?

Albumin

How is plasma volume regulated when fluid is lost?

Osmoreceptors trigger ADH release to increase water reabsorption

What is the main function of red blood cells?

Transport oxygen

What molecule allows RBCs to carry oxygen?

Hemoglobin

Why do RBCs lack mitochondria?

So they do not use the oxygen they transport

Define anemia

A condition where oxygen delivery is reduced due to low RBC count or hemoglobin

Why does anemia cause fatigue?

Tissues receive less oxygen for ATP production

What determines ABO blood type?

Antigens present on the surface of red blood cells

What antibodies are present in type A blood?

Anti-B antibodies

Why is type O the universal donor?

It has no A or B antigens

Why is type AB the universal recipient?

It has no anti-A or anti-B antibodies

What causes a transfusion reaction?

Antibody-antigen binding leading to agglutination

Why don't Rh-negative individuals naturally have anti-Rh antibodies?

Antibodies form only after exposure to Rh-positive blood

Which blood vessels carry blood away from the heart?

Arteries

Which blood vessels regulate resistance and blood flow?

Arterioles

Where does gas and nutrient exchange occur?

Capillaries

What is the function of veins?

Return blood to the heart and act as blood reservoirs

What is pulmonary circulation?

Blood flow between the heart and lungs

What is systemic circulation?

Blood flow between the heart and body tissues

Which heart chamber pumps blood to the lungs?

Right ventricle

Which heart chamber pumps blood to the body?

Left ventricle

What is the function of the septum?

Prevents mixing of oxygenated and deoxygenated blood

What do atrioventricular (AV) valves prevent?

Backflow of blood from ventricles into atria

What causes the "lub" heart sound?

Closing of AV valves

What causes the "dub" heart sound?

Closing of semilunar valves

Define systole

Contraction of the heart

Define diastole

Relaxation of the heart

What is end-diastolic volume (EDV)?

Blood in the ventricles at the end of filling

What is end-systolic volume (ESV)?

Blood remaining in ventricles after contraction

What is stroke volume?

EDV minus ESV

What happens during isovolumetric contraction?

Ventricular pressure increases with no change in volume

What structure is the heart's pacemaker?

Sinoatrial (SA) node

Why is the AV node delay important?

Allows time for ventricular filling

What is the correct cardiac conduction pathway?

SA node → AV node → bundle of His → bundle branches → Purkinje fibers

What does the P wave represent on an ECG?

Atrial depolarization

What does the QRS complex represent?

Ventricular depolarization

What does the T wave represent?

Ventricular repolarization

What does an ECG measure?

Electrical activity of the heart, not contraction