Blood Components and Functions Quiz

General Overview

• Blood is a complex fluid performing crucial roles in transport and defense.

Components of Blood and Functions

• Erythrocytes (red blood cells): Carry oxygen from lungs to cells and carbon dioxide from cells to lungs.
• Plasma: Transports nutrients, hormones, urea, proteins, antibodies, gases, and waste products.
• Thrombocytes (platelets): Involved in blood clotting.
• Leukocytes (white blood cells): Key components of the immune system. Lymphocytes produce antibodies, while other leukocytes (phagocytes) engulf pathogens.

Capillary Adaptations for Material Exchange

• Capillaries are the smallest blood vessels (about 10µm diameter).
• Extensive branching creates a large surface area for efficient material exchange.
• Thin walls facilitate easy diffusion between blood and tissue cells.
• Pores in the capillary walls allow blood plasma to leak out, forming tissue fluid. This fluid bathes tissues, enabling exchange of materials. Tissue fluid differs from blood plasma, lacking large proteins.

Arteries and Veins: Structure and Function

• Arteries have thick, elastic walls to withstand high pressure blood flow from heart.
• Veins have thinner walls, wider lumens, and valves to prevent backflow.

Adaptations of Arteries for Blood Transport

• Tunica Externa: Tough outer layer of connective tissue providing structural support and flexibility.
• Tunica Media: Thick layer of smooth muscle and elastic fibers maintaining high blood pressure.
• Tunica Intima: Smooth endothelium that minimizes friction aiding blood flow. Elastic fibers allow for recoil maintaining blood pressure.

Adaptations of Veins for Blood Return

• Thin walls: Veins have thinner walls enabling compression from surrounding muscles aiding in blood flow.
• Valves: Act to prevent blood backflow, ensuring unidirectional flow to the heart.
• Wider lumens: Allows blood to flow through veins under lower pressure.

Measurement of Pulse Rates

• Pulse rates are measured by feeling pressure waves in arteries. Usually measured at wrists (radial artery) and neck (carotid artery).
• Traditional methods involve counting beats per minute manually.
• Digital methods use devices (e.g., pulse oximeters).

Causes and Consequences of Coronary Artery Occlusion

• Coronary heart disease (CHD) refers to conditions where coronary arteries are narrowed or blocked by fatty deposits, decreasing blood supply to heart tissue.
• Factors contributing to CHD include raised blood pressure, smoking, high salt intake, diet high in saturated fat and cholesterol etc.
• Consequences include angina, heart attack, and heart failure, potentially leading to tissue death (myocardial infarction).

Release and Reuptake of Tissue Fluid

• Tissue fluid is formed when blood plasma leaks out of capillaries into surrounding tissues.
• This fluid contains less protein and large molecules than blood.
• Some fluid is reabsorbed into capillaries, while the rest is collected by the lymphatic system.

Exchange of Substances Between Tissue Fluid and Cells

• Cells obtain oxygen, glucose, and nutrients from tissue fluid via diffusion or active transport, in response to concentration gradients.
• Waste products (CO2, metabolic wastes) diffuse into the tissue fluid, eventually transported out of the body.

Drainage of Excess Tissue Fluid into Lymph Ducts

• Tissue fluid collects in blind-ended lymphatic vessels.
• Lymph vessels have valves (one way) preventing backflow and move lymph into wider lymphatic vessels.
• These vessels eventually drain into lymphatic ducts linking to the circulatory system.

Single vs. Double Circulation

• Fish have single circulation, blood passes through the heart once per complete circuit.
• Mammals have double circulation, blood passes through the heart twice per complete circuit.

Adaptations of the Mammalian Heart

• The heart's four chambers (two atria, two ventricles) ensure unidirectional blood flow, with separate circuits for pulmonary and systemic circulation.
• Atrioventricular and semilunar valves prevent backflow.
• Cardiac muscle enables coordinated contractions.
• Coronary vessels provide blood to the heart muscle.

Stages in the Cardiac Cycle

• The cardiac cycle shows the coordinated sequence of events enabling effective functioning of the heart.
• The atria and ventricles contract and relax rhythmically, ensuring blood is pumped under pressure throughout the body.
• Sinoatrial node initiates the cycle via electrical signals.