Cardiovascular System Functions and Blood Flow

Cardiovascular System Functions

• Four major functions of the cardiovascular system: transportation of oxygen, carbon dioxide, heat, hormones, white blood cells, nutrients, and waste products.
• Systemic circuit: supplies oxygenated blood to all body tissues.
• Pulmonary circuit: picks up oxygen and eliminates carbon dioxide as blood passes through.

Blood Flow Through Circuits

• Blood flows from the heart to the lungs (pulmonary circuit) and then back to the heart.
• Blood flows from the heart to the body (systemic circuit) and then back to the heart.

Arteries and Veins Identification

• Arteries carry blood away from the heart.
• Veins carry blood toward the heart.
• Arteries have thicker muscle layers in their walls to withstand higher pressure than veins.
• Veins have valves to prevent backflow.
• Blood pressure decreases as blood moves further from the heart.

Microscopic Arteries and Veins

• Arteries have a smaller lumen compared to veins.
• Veins often appear irregular or collapsed in cross-section.
• Capillaries are extremely thin-walled, allowing for gas and nutrient exchange with interstitial fluid.
• Blood vessels are lined with simple squamous epithelium.

Major Arteries and Veins

• Arteries are named based on location or region supplied.
• Examples: ascending aorta, aortic arch, descending aorta, celiac trunk, external carotid, internal carotid, femoral artery, subclavian, external iliac, internal iliac, brachial, radial, ulnar.
• Veins return blood to the heart and are named similarly.
• Examples: superior vena cava, inferior vena cava, brachiocephalic vein, common iliac vein, renal vein, hepatic portal vein.

Unique Circulations

• Cerebral arterial circle (circle of Willis): provides redundant blood supply to the brain.
• Hepatic portal system: carries blood from the digestive organs to the liver for processing.

Fetal Circulation

• Fetal systems like the lungs and digestive system are non-functional.
• Gas and nutrient exchange occurs via the placenta.
• Umbilical arteries carry deoxygenated blood to the placenta.
• Umbilical vein carries oxygenated blood to the fetus.
• Ductus venosus shunts blood from the umbilical vein to the inferior vena cava, bypassing the liver.
• Foramen ovale allows blood to bypass the lungs by flowing directly from the right atrium to the left atrium.
• Ductus arteriosus shunts blood from the pulmonary trunk to the aorta, bypassing the lungs.
• After birth, these shunts close, with structures transforming into adult versions.

Lymphatic System Functions

• Three main functions: fluid balance, immune defense, and nutrient absorption.

Lymph Formation and Return

• Lymph is formed from excess interstitial fluid.
• Lymph is returned to the blood through lymphatic vessels and ducts.
• One-way valves in lymphatic vessels are essential for unidirectional flow.
• Lymph nodes and vessels filter lymph and trap pathogens and debris.

Lymph Organs and Locations

• Lymph organs and tissues include: thymus, spleen, tonsils (palatine, lingual, pharyngeal), lymphatic nodules, aggregated lymphatic follicles, and bone marrow.
• Thymus: T-cell maturation.
• Spleen: filters blood, stores platelets.
• Tonsils: trap pathogens.
• Lymphatic nodules/MALT: immune surveillance in digestive and respiratory tracts.
• Bone marrow: blood cell production, including lymphocytes.

Lymph Node Structures

• Lymph nodes are located along lymphatic vessels.
• Lymph nodes contain lymphocytes and macrophages that filter lymph.
• Lymph nodes have a cortex and medulla, with specialized areas for B and T cell proliferation.

Edema

• Edema is swelling caused by excess interstitial fluid.

Lymph Movement

• Three mechanisms for lymph movement: muscle pump, respiratory pump, and one-way valves.

Lymph Return to Blood

• Lymph returns to the cardiovascular system through the right lymphatic duct (right side of the body) or the thoracic duct (left side and lower body).
• Lymph enters the bloodstream at the subclavian veins.

Lymphatic Vessel Differences

• Lymphatic vessels have thinner walls compared to blood vessels (veins).
• More valves are present in lymphatic vessels than in veins.

Hemopoiesis

• Hemopoiesis occurs in the yolk sac during fetal development, then the liver/spleen and finally the bone marrow.
• In adults, hemopoiesis primarily occurs in red bone marrow.

Lymph Nodule Abundance

• Extensive lymph nodules in respiratory, digestive, and urinary tracts facilitate immune surveillance at pathogen entry points.

Plasma, Serum, Interstitial Fluid, and Lymph

• Plasma: Blood's liquid portion with clotting factors.
• Serum: Plasma without clotting factors.
• Interstitial fluid: Fluid surrounding cells, similar to plasma but lacking proteins.
• Lymph: Circulates through lymphatic system, removing interstitial fluid and waste.

This quiz covers the essential functions of the cardiovascular system, including the transportation of various substances and the differences between arteries and veins. It also explains the blood flow through the systemic and pulmonary circuits. Test your knowledge on how blood circulates and the structural differences in blood vessels.