anatomy heart unit

Unique characteristics of cardiac muscle

Involuntary, striated, branched cells with one nucleus; intercalated discs allow electrical connection; contracts rhythmically without fatigue

Systemic circulation

Delivers oxygenated blood to body cells and carries away waste

Pulmonary circulation

Carries blood to lungs to remove carbon dioxide and pick up oxygen

Heart chambers

2 atria receive blood; 2 ventricles pump blood out

Septum

Wall separating right and left sides of the heart

Heart valves

Ensure one-way flow of blood

Tricuspid valve

Right atrioventricular valve between right atrium and right ventricle

Mitral (bicuspid) valve

Left atrioventricular valve between left atrium and left ventricle

Pulmonary semilunar valve

Between right ventricle and pulmonary artery

Aortic semilunar valve

Between left ventricle and aorta

Erythrocytes

Red blood cells that transport oxygen

Leukocytes

White blood cells that fight infection

Thrombocytes

Platelets that help blood clot

Hematocrit

Percentage of red blood cells in blood volume (36–53%)

Purpose of hematocrit

Measures RBC levels to help diagnose anemia, dehydration, and other conditions

Neutrophils

Fight bacterial infections and inflammation

Eosinophils

Fight parasitic infections and trigger allergic responses

Basophils

Release histamine during allergic reactions

Monocytes

Clean up dead cells; become macrophages or dendritic cells

Lymphocytes

Defend against infections; B cells make antibodies, T cells destroy infected cells

Leukocyte percentages

Used by doctors to identify infections, allergies, and immune disorders

Plasma

Liquid portion of blood (92% water) that transports nutrients, gases, and maintains balance

Plasma proteins

Albumin (blood pressure), globulins (antibodies), fibrinogen (clotting)

Pathway of oxygenated blood

Lungs → pulmonary veins → left atrium → left ventricle → aorta → body

Pathway of deoxygenated blood

Body → vena cava → right atrium → right ventricle → pulmonary arteries → lungs

Blood types

A, B, AB, O with positive or negative Rh factor

Rh factor

Presence (+) or absence (-) of Rh antigen

Genotypes of blood types

A = AA or AO; B = BB or BO; AB = AB; O = OO

Type A blood

A antigens and anti-B antibodies

Type B blood

B antigens and anti-A antibodies

Type AB blood

A and B antigens and no antibodies

Type O blood

No antigens and both anti-A and anti-B antibodies

Punnett squares

Used to predict offspring blood types from parent genotypes

Cooley’s anemia

Genetic disorder (thalassemia) causing reduced hemoglobin production

Sickle cell anemia

Genetic disorder where red blood cells become sickle-shaped and block blood flow

Pericardium

Protective sac around the heart with fluid to reduce friction

Layers of heart wall

Epicardium (outer), myocardium (muscle), endocardium (inner lining)

Coronary arteries

Supply blood to the heart muscle

Splenomegaly

Enlarged spleen that filters blood and recycles iron