Cardiovascular System: Blood, Heart, and Blood Vessels – Study Guide

Ch. 17 – Blood

Functions of Blood

Blood is a vital connective tissue with multiple essential functions in the human body:

• Distribution: Transports oxygen, nutrients, hormones, and waste products throughout the body.

• Regulation: Maintains body temperature, pH balance, and fluid volume.

• Protection: Prevents blood loss (clotting) and fights infection (immune response).

Components of Blood

• Plasma: The liquid matrix (about 55% of blood) containing water, proteins, electrolytes, nutrients, and waste products.

• Platelets (Thrombocytes): Cell fragments involved in blood clotting.

• Leukocytes (White Blood Cells): Cells of the immune system that defend against pathogens.

• Erythrocytes (Red Blood Cells): Specialized for oxygen transport.

Properties of Red Blood Cells (Erythrocytes)

• Biconcave disc shape: Increases surface area for gas exchange.

• Anucleate: Mature RBCs lack a nucleus, allowing more room for hemoglobin.

• Hemoglobin: The protein that binds and transports oxygen.

White Blood Cells (Leukocytes): Types and Functions

• Neutrophils: Most numerous; phagocytize bacteria.

• Lymphocytes: B and T cells; involved in adaptive immunity.

• Monocytes: Become macrophages; phagocytize pathogens and debris.

• Eosinophils: Combat parasites; involved in allergic responses.

• Basophils: Release histamine; involved in inflammation.

By number: Neutrophils > Lymphocytes > Monocytes > Eosinophils > Basophils ("Never Let Monkeys Eat Bananas").

Blood Types and Rh Factors

• Blood types: A, B, AB, O – determined by presence of A and/or B antigens on RBCs.

• Rh factor: Presence (+) or absence (–) of Rh antigen (D antigen).

Antigens and Antibodies

• Antigens: Surface proteins on RBCs; determine blood type.

• Antibodies: Proteins in plasma that recognize and attack foreign antigens.

• Transfusion reactions: Recipient's antibodies attack donor's antigens if incompatible.

Blood Type Compatibility Table

Blood Type	Antigens	Antibodies	Can Donate To	Can Receive From
A	A	Anti-B	A, AB	A, O
B	B	Anti-A	B, AB	B, O
AB	A, B	None	AB	A, B, AB, O
O	None	Anti-A, Anti-B	A, B, AB, O	O

Agglutination

• Agglutination: Clumping of RBCs due to antibody-antigen reaction; can block blood vessels and is dangerous in transfusion reactions.

Hematopoiesis and Related Processes

• Hematopoiesis: Formation of all blood cells in red bone marrow.

• Erythropoiesis: Production of red blood cells.

• Leukopoiesis: Production of white blood cells.

• Thrombopoiesis: Production of platelets.

• Key cells: Hematopoietic stem cells give rise to all blood cell types; megakaryocytes produce platelets.

Causes of Hypoxia

• Low oxygen availability (high altitude, lung disease)

• Decreased RBC count (anemia, blood loss)

• Defective hemoglobin

Causes of Anemia

• Blood loss (hemorrhagic anemia)

• Decreased RBC production (iron deficiency, vitamin B12 deficiency)

• Increased RBC destruction (hemolytic anemia)

Megakaryocytes

• Large bone marrow cells that fragment to form platelets, essential for blood clotting.

Ch. 18 – The Heart

Heart Structure

• Chambers: Right atrium, right ventricle, left atrium, left ventricle.

• Major vessels: Superior/inferior vena cava, pulmonary arteries/veins, aorta.

• Valves: Atrioventricular (AV) valves (tricuspid, bicuspid/mitral), semilunar (SL) valves (pulmonary, aortic).

• Chordae tendineae: Tendinous cords anchoring AV valves to papillary muscles, preventing valve prolapse.

Pathway of Blood Through the Heart

1. Deoxygenated blood enters right atrium via vena cavae.

2. Passes through tricuspid valve to right ventricle.

3. Pumped through pulmonary valve to pulmonary arteries, to lungs.

4. Oxygenated blood returns via pulmonary veins to left atrium.

5. Passes through mitral valve to left ventricle.

6. Pumped through aortic valve to aorta and systemic circulation.

Oxygen-Rich vs. Oxygen-Poor Blood

• Oxygen-poor: Right side of heart, pulmonary arteries.

• Oxygen-rich: Left side of heart, pulmonary veins, aorta.

Cardiac Muscle Tissue

• Striated: Like skeletal muscle, but with unique features.

• Intercalated discs: Specialized junctions for synchronized contraction.

Ch. 19 – Blood Vessels

Types of Blood Vessels

• Arteries: Carry blood away from the heart; thick, elastic walls.

• Arterioles: Small branches of arteries; regulate blood flow into capillaries.

• Capillaries: Microscopic vessels for exchange of gases, nutrients, and wastes.

• Venules: Collect blood from capillaries; merge to form veins.

• Veins: Return blood to the heart; thinner walls, valves prevent backflow.

Microstructure of Veins and Arteries

• Tunica intima: Innermost layer; endothelium.

• Tunica media: Middle layer; smooth muscle and elastic fibers (thicker in arteries).

• Tunica externa (adventitia): Outermost layer; connective tissue.

Types of Arteries

• Elastic arteries: Largest; stretch and recoil (e.g., aorta).

• Muscular arteries: Distribute blood to organs; more smooth muscle.

• Arterioles: Smallest arteries; control flow into capillary beds.

Blood Pressure in Veins vs. Arteries

• Arteries: High pressure, pulsatile.

• Veins: Low pressure, steady flow; valves prevent backflow.

Arterial Blood Pressure Components

• Systolic pressure: Peak pressure during ventricular contraction.

• Diastolic pressure: Lowest pressure during ventricular relaxation.

• Pulse pressure: Difference between systolic and diastolic pressures.

Mean Arterial Pressure (MAP)

• Formula:

$MAP = \text{Diastolic Pressure} + \frac{1}{3} (\text{Systolic Pressure} - \text{Diastolic Pressure})$

Factors Influencing Blood Pressure

• Cardiac Output (CO): Volume of blood pumped by the heart per minute.

• Peripheral Resistance (PR): Resistance to blood flow in vessels.

• Blood Volume: Total amount of blood in the circulatory system.

Increases in any of these factors raise blood pressure; decreases lower it.

Hormonal Control of Blood Pressure

• Vasoconstriction (increase BP): Norepinephrine, epinephrine, angiotensin II, antidiuretic hormone (ADH).

• Vasodilation (decrease BP): Atrial natriuretic peptide (ANP).

Blood Pressure Disorders

• Hypertension: High blood pressure; risk factor for heart disease and stroke.

• Hypotension: Low blood pressure; can cause dizziness and fainting.

Vascular Diseases

• Atherosclerosis: Plaque buildup in arteries, leading to reduced blood flow.

• Diabetes: Can damage blood vessels, increasing risk of atherosclerosis and hypertension.

• Hypertension: Chronic high blood pressure; damages vessels and organs.

Example: A patient with type O negative blood can donate to any other blood type (universal donor) but can only receive from O negative donors.

Additional info: For more detailed diagrams and histology slides, refer to your course PowerPoints and textbook figures as indicated in your syllabus.