Functions and Composition of Blood

Blood

A liquid connective tissue made of cells suspended in plasma that performs transportation, regulation, and protection functions.

Transportation

Moves oxygen, nutrients, hormones, and waste throughout the body.

Regulation

Maintains body temperature, pH balance, and fluid volume.

Protection

Prevents blood loss via clotting and combats infection with white blood cells and antibodies.

Plasma

The straw-colored liquid part of blood (about 55%) composed mostly of water, proteins, and other solutes.

Formed Elements

The cellular portion of blood (about 45%), including red blood cells, white blood cells, and platelets.

Albumin

A plasma protein that maintains blood's osmotic pressure.

Globulins

Plasma proteins involved in immune response (antibodies) and transport of substances.

Fibrinogen

A plasma protein involved in blood clotting by converting into fibrin.

Electrolytes

Ions like sodium, potassium, calcium, and bicarbonate that help with nerve function and fluid balance.

Gases

Oxygen and carbon dioxide dissolved in plasma.

Nutrients

Glucose, amino acids, and lipids absorbed from digestion and transported in blood.

Waste Products

Substances like urea and creatinine removed from the body.

Hormones

Chemical messengers transported in the bloodstream to target organs.

Erythrocytes (Red Blood Cells or RBCs)

Transport oxygen (via hemoglobin) and some carbon dioxide.

Structure of Erythrocytes

Biconcave, no nucleus, filled with hemoglobin.

Hemoglobin

An iron-containing protein that binds oxygen.

Leukocytes (White Blood Cells or WBCs)

Defend the body against infection and disease.

Granulocytes

A type of leukocyte that includes neutrophils, eosinophils, and basophils.

Neutrophils

Phagocytize bacteria; first responders.

Eosinophils

Combat parasites; involved in allergies.

Basophils

Release histamine in allergic reactions.

Agranulocytes

A type of leukocyte that includes lymphocytes and monocytes.

Lymphocytes

Include B cells (produce antibodies) and T cells (attack infected cells).

Monocytes

Become macrophages that engulf pathogens.

Platelets (Thrombocytes)

Aid in blood clotting by forming plugs in vessel injuries.

Hematopoiesis

The process of forming blood cells in red bone marrow.

Hemocytoblasts

Stem cells in bone marrow that differentiate into all types of blood cells.

Hemostasis

The process of stopping bleeding.

Vascular Spasm

Blood vessels constrict to reduce blood flow.

Platelet Plug Formation

Platelets stick to damaged vessel and each other.

Coagulation

Fibrinogen converts into fibrin, forming a clot.

Antigen

A molecule on the surface of red blood cells that can trigger an immune response.

Antibody

A protein that reacts against specific antigens.

ABO System

Type A: Has A antigens and anti-B antibodies.

Type A

Has A antigens and anti-B antibodies.

Type B

Has B antigens and anti-A antibodies.

Type AB

Has both A and B antigens, no antibodies (universal recipient).

Type O

No antigens, has anti-A and anti-B antibodies (universal donor).

Rh+

Has Rh antigen.

Rh−

Lacks Rh antigen; can develop anti-Rh antibodies if exposed.

Cardiovascular System

The heart and blood vessels responsible for circulating blood.

Functions of Cardiovascular System

Transportation, regulation, protection.

Pericardium

A protective double-layered sac surrounding the heart.

Myocardium

The muscular middle layer of the heart wall that contracts to pump blood.

Endocardium

The smooth inner lining of the heart chambers and valves.

Atria

Upper chambers that receive blood.

Ventricles

Lower chambers that pump blood out.

Tricuspid Valve

Between right atrium and right ventricle.

Bicuspid/Mitral Valve

Between left atrium and left ventricle.

Pulmonary Valve

Between right ventricle and pulmonary artery.

Aortic Valve

Between left ventricle and aorta.

Pulmonary Circulation

Carries deoxygenated blood from right heart to lungs and returns oxygenated blood to the left heart.

Systemic Circulation

Carries oxygenated blood from the left heart to the body and returns deoxygenated blood to the right heart.

Sinoatrial (SA) Node

The heart's natural pacemaker; initiates the heartbeat.

Atrioventricular (AV) Node

Delays impulse before passing it to ventricles.

Bundle of His

Conducts impulse from AV node through the interventricular septum.

Bundle Branches

Carry impulse through the septum to the apex.

Purkinje Fibers

Spread impulse through ventricles for contraction.

Cardiac Cycle

One complete heartbeat (contraction and relaxation).

Systole

Contraction phase when chambers pump blood.

Diastole

Relaxation phase when chambers fill with blood.

"Lub" (S1)

Sound from AV valves closing.

"Dub" (S2)

Sound from semilunar valves closing.

Arteries

Vessels that carry blood away from the heart (usually oxygenated).

Veins

Vessels that carry blood toward the heart (usually deoxygenated).

Capillaries

Tiny vessels where exchange of gases, nutrients, and waste occurs between blood and tissues.

Aorta

The largest artery, carrying blood from the left ventricle to the body.

Pulmonary Arteries

Carry deoxygenated blood from the right ventricle to the lungs.

Pulmonary Veins

Bring oxygenated blood from the lungs to the left atrium.

Superior Vena Cava

Returns deoxygenated blood from the upper body to the right atrium.

Inferior Vena Cava

Returns deoxygenated blood from the lower body to the right atrium.