Kaplan: Cardiovascular System

What type of tissue is blood, and what is its pH and viscosity?

Blood is a fluid connective tissue with a pH of about 7.4 that is more viscous than water.

What are the main components of blood?

• Formed elements (red blood cells, white blood cells, and platelets)

• an extracellular matrix called plasma, molecules, cell fragments, and debris.

Red Blood Cells (Erythrocytes)

0.008 mm; participate in gas exchange (primarily oxygen and carbon dioxide).

White Blood Cells (Leukocytes)

0.02 mm; protect the body from foreign substances by eliciting an immune response.

Platelets (Thrombocytes)

0.003 mm; aid in blood clotting and wound healing.

What is plasma and what is it primarily composed of?

The fluid extracellular matrix of blood in which formed elements remain suspended; it consists of about 92% water.

What is the average blood volume and percentage of body weight for a 70-kilogram human?

5 liters, accounting for roughly 8% of a person's body weight.

What layers form when a blood sample is spun in a centrifuge, and what are their percentages of whole blood?

• Top layer: Plasma (55% of whole blood).

• Middle thin white layer: Buffy coat, containing leukocytes and platelets (<1% of whole blood).

• Bottom reddish mass: Erythrocytes (45% of whole blood).

How does blood viscosity affect blood flow?

Blood viscosity is indirectly (inversely) proportional to blood flow:

• when viscosity is high, blood flow decreases;

• when viscosity is low (thin blood), blood flow increases.

What are the three primary functions of blood?

• Transportation

• Regulation

• Protection

What four categories of substances does blood transport throughout the body?

• Gases: Oxygen from lungs to cells; carbon dioxide from cells to lungs for elimination.

• Nutrients: From the digestive tract and storage sites to various body locations.

• Wastes: To the liver (excreted as bile) and kidneys (excreted as urine).

• Hormones: From producing glands to target organs.

What is albumin and what are its functions?

• The main protein in blood (accounting for roughly 60% of plasma proteins);

• it maintains water balance and acts as a carrier protein to shuttle molecules throughout the body.

What regulatory functions does blood perform, and how does it regulate body temperature?

• Blood regulates body temperature, chemical balance, and water balance.

• Plasma absorbs/releases heat: blood vessels expand (vasodilate) in high heat to slow blood flow and increase heat loss, or contract (vasoconstrict) in low temperatures to release less heat.

How does blood protect the body?

It carries white blood cells and antibodies to destroy pathogens/foreign invaders, and uses platelets and plasma proteins to prevent extensive blood loss from damaged vessels.

What is hemostasis?

The physiological process activated when blood vessels are damaged that maintains blood in its fluid state and stops blood from leaking out through clot formation.

What are the three sequential steps of hemostasis?

• Vascular spasm (vasoconstriction): Blood vessels constrict to reduce blood loss (works best in small vessels).

• Platelet plug formation: Platelets adhere to the damaged epithelial wall and aggregate (stick together) to form a temporary seal.

• Blood coagulation (blood clotting): Fibrin threads form a protein mesh ("molecular glue") around the platelet plug, trapping red blood cells and platelets to form a stable clot for wound healing.

How are blood groups classified, and what are antigens vs. antibodies?

• Classified by inherited differences in red blood cell surface antigens.

• Antibodies are plasma proteins that identify specific blood groups and recognize foreign substances to alert the immune system.

Describe the antigens on RBCs and antibodies in plasma for the four major ABO blood groups.

• Blood group A: Type A antigens on RBCs; anti-B antibodies in plasma.

• Blood group B: Type B antigens on RBCs; anti-A antibodies in plasma.

• Blood group O: Neither A nor B antigens on RBCs; both anti-A and anti-B antibodies in plasma.

• Blood group AB: Both A and B antigens on RBCs; neither A nor B antibodies in plasma.

What is the Rh factor and how does it expand the major blood groups?

A protein that may be present (+) or absent (–) on a red blood cell's surface, expanding the four ABO groups into eight major blood types: A+, A–, B+, B–, O+, O–, AB+, and AB–.

Which blood types are the universal donor and universal acceptor, and what can each blood group accept/donate?

• Type O (Universal donor): Can donate to AB, A, B, O; can accept only from O.

• Type AB (Universal acceptor): Can accept from AB, A, B, O; can donate only to AB.

• Type A: Can accept from A, O; can donate to A, AB.

• Type B: Can accept from B, O; can donate to B, AB.

What is agglutination and what does it indicate during blood typing?

• Clumping that occurs when a blood sample is mixed with an antiserum;

• it indicates that antibodies have bound to matching antigens present on the surface of the red blood cells.

What organs form the cardiovascular system and why is it called a closed-loop system?

• Composed of the blood, heart, and blood vessels;

• it is a closed-loop system because blood is contained within the heart or blood vessels at all times.

Arteries:

Carry blood away from the heart toward organs/tissues; branch into smaller arterioles.

Capillaries:

Tiny, thin-walled vessels with a large surface area that slow blood flow to facilitate gas, nutrient, and waste exchange around tissues.

Veins:

Carry blood toward the heart from organs/tissues; formed from smaller venules that collect blood from capillaries.

Where is the heart located and what are its four chambers and dividing wall?

• Located between the lungs in the middle of the chest, behind and slightly to the left of the sternum.

• It has two upper chambers (atria) and two lower chambers (ventricles), separated by a muscular wall called the septum.

What are the three layers of the heart wall from outermost to innermost?

• Pericardium: Outer layer

• Myocardium: Middle layer (contains most of the cardiac muscle tissue)

• Endocardium: Innermost layer

What are the four valves of the heart and what blood flow does each regulate?

• Tricuspid valve: Between the right atrium and right ventricle.

• Pulmonary valve: From the right ventricle into the pulmonary artery.

• Mitral valve: Between the left atrium and left ventricle.

• Aortic valve: From the left ventricle into the aorta (the largest artery in the body).

Trace the pathway of Systemic Circulation (oxygenated blood).

1. Pulmonary veins push oxygenated blood into the left atrium.

2. Left atrium relaxes and blood drains through the mitral valve into the left ventricle.

3. Left ventricle pumps oxygenated blood through the aortic valve into the aorta.

4. Blood travels through arteries and arterioles to tissue capillaries for exchange (then returns via venules and veins).

Trace the pathway of Pulmonary Circulation (deoxygenated blood).

1. Superior and Inferior Vena Cava bring deoxygenated blood from the upper and lower body into the right atrium.

2. Blood moves from the right atrium through the tricuspid valve into the right ventricle.

3. Right ventricle contracts, pushing blood through the pulmonary valve into the pulmonary artery.

4. Blood becomes oxygenated in the lungs and returns to the left atrium via pulmonary veins.

What is the cardiac cycle, and what is the difference between systole and diastole?

The complete cycle beginning with atrial contraction and ending with ventricular contraction.

• Systole: Period of heart contraction when blood is pumped into circulation.

• Diastole: Period of relaxation when the heart chambers fill with blood.

How does blood volume relate to blood pressure?

They are directly proportional: if blood volume increases, blood pressure increases (and vice versa).

What is an electrocardiogram (EKG), and what does each wave/segment represent?

A graph recording the heart's electrical activity, rate, and rhythm over time:

• P wave: Atrial contraction (atrial systole).

• QRS complex (Q, R, and S waves): Ventricular contraction (ventricular systole).

• T wave: Ventricular relaxation (ventricular diastole).

• ST segment: Flat line between the S wave and T wave.