The Human Circulatory System Components and Functions Components

The Human Circulatory System Components and Functions

Components of Blood • • Plasma Red blood cells White blood cells Platelets

Plasma • Makes up 55% of the blood • Contains dissolved ions including; Ca, Mg, Na, HCO 3 • Wastes and nutrients • Proteins (antibodies, enzymes, hormones, clot factors) • Water (91% H 2 O)

Red Blood Cells • Most numerous cells • Shaped like bi-concave discs • Produced in the bone marrow • Mature RBC’s do NOT contain a nucleus • Hemoglobin is an ironcontaining protein in RBC’s that binds to O 2 and assist in its transport

RBCs, WBCs & Platelets

White Blood Cells • Larger than RBC’s • Produced in the bone marrow and lymph nodes • Single or multinucleated • Necessary to fight pathogens (ie. bacteria, viruses)

Types of White Blood Cells • Phagocytes (engulf foreign pathogens via phagocytosis) -Macrophage -neutrophils -monocytes • Lymphocytes -B cells (produce antibodies) -T cells -T 4 helper -Killer T cells

Blood Cell Origin and Differentiation

Platelets • Assist in the clotting process • Fragments, contain no nucleus • Made in bone marrow

Blood Clotting • Clotting involves a series of enzyme controlled reactions • Injury to blood vessel- causes platelets to rupture- initiating clotting reactions. • Prothrombin- Thrombin- • Fibrinogen-- Fibrin, which forms a fibrous mesh at the site of the injury. • The mesh traps blood cells, forming a clot

Coagulation Pathway

Transport Vessels • Blood circulates through the human body within closed blood vessels

Arteries • Carry oxygen-rich blood away from the heart to the body • Thick, muscular walls to withstand blood pressure • Rhythmic expansion and contraction of the arteries produced by the heart is called the pulse.

Capillaries • Smallest branches of arteries • One cell layer thick • They are the site of exchange of materials between the blood and tissues http: //www. youtube. com/watch? v=h. Dbfkfgc 1 xk&feature=related

Veins • Blood flows from the capillaries into veins • Veins are thin walled and carry oxygen poor blood back to the heart • Contain valves that prevent backflow of blood due to the low pressure in the veins *Blood flow in the veins is assisted by the contraction of your muscles.

Intercellular Fluid and Lymph • Some of the plasma leaves the capillaries and bathes the cells. This is called Intercellular Fluid (ICF). • Excess ICF is drained into tiny vessels called lymphatic vessels. It is then called lymphatic fluid. • Lymph fluid empties into the large veins that return blood to the heart.