Science 30 UA

What is the cardiovascular system also called?

The circulatory system.

Four main functions of the circulatory system?

Transport O2/nutrients, transport hormones, distribute heat, defend against disease.

Three main parts of the circulatory system?

Heart (pump), Blood vessels (transport), Blood (connective tissue, 4–6 L in adults).

Arteries carry blood…?

Away from the heart.

Veins carry blood…?

Toward the heart.

Which side of the heart carries deoxygenated blood?

Right side (blue blood).

Which side of the heart carries oxygenated blood?

Left side (red blood).

Function of the atria?

Collect blood entering the heart.

Function of the ventricles?

Pump blood out of the heart.

Where does gas and nutrient exchange occur?

Capillaries.

Where does blood become oxygenated?

In the lungs (pulmonary capillaries).

Systemic circulation = ?

Blood flow from heart to body systems.

Pulmonary circulation = ?

Blood flow from heart to lungs.

Three types of blood vessels?

Arteries, capillaries, veins.

Why do arteries have thick, elastic walls?

To stretch and withstand pressure during heart contractions.

What is the pulse?

Stretching of artery walls as the heart contracts.

What are arterioles?

Small branches of arteries leading to capillaries.

What is vasodilation?

Relaxation of arteriole walls → increased blood flow.

What is vasoconstriction?

Contraction of arteriole walls → reduced blood flow.

Function of capillaries?

Exchange O2, CO2, nutrients, and wastes by diffusion.

Why are capillary walls one cell thick?

Allows easy exchange of gases and nutrients.

Function of veins?

Carry blood back to the heart under low pressure.

Two mechanisms that help veins return blood to the heart?

One-way valves and skeletal muscle contractions.

What are varicose veins?

Enlarged, twisted veins caused by valve failure.

What tissue makes up heart walls?

Cardiac muscle tissue.

What separates the right and left sides of the heart?

The septum.

Two upper chambers of the heart?

Atria.

Two lower chambers of the heart?

Ventricles.

Function of AV (atrioventricular) valves?

Prevent backflow from ventricles to atria.

Function of semilunar valves?

Prevent backflow from arteries into ventricles.

Path of blood: body → heart (right atrium)?

Vena cava → right atrium.

Path of blood: right atrium → right ventricle?

Through right AV valve.

Path of blood: right ventricle → lungs?

Through pulmonary valve → pulmonary artery → lungs.

Path of blood: lungs → left atrium?

Through pulmonary veins.

Path of blood: left atrium → left ventricle?

Through left AV valve.

Path of blood: left ventricle → body?

Through aortic valve → aorta → systemic circulation.

What is stroke volume?

Amount of blood pumped per beat (~70 mL).

Average resting heart rate?

~70–80 beats per minute.

What is a cardiac cycle?

One heartbeat = diastole + systole.

What is diastole?

Relaxation phase → ventricles fill with blood.

What is systole?

Contraction phase → ventricles pump blood, AV valves close (“lubb”).

What causes the “dubb” sound?

Semilunar valves closing as ventricles relax.

What is a heart murmur?

Leaky valve → blood backflow, less efficient pumping.

What is the heart’s pacemaker?

SA node in right atrium.

Function of pacemaker?

Generates electrical signals to coordinate heartbeat.

What is blood pressure?

Force of blood against vessel walls.

How is blood pressure measured?

With sphygmomanometer in mmHg.

What is systolic pressure?

Pressure during ventricular contraction (numerator).

What is diastolic pressure?

Pressure during ventricular relaxation (denominator).

Normal blood pressure range?

90/50 to 135/90 mmHg.

What is hypertension?

Chronic high blood pressure (>140/90).

Why is high blood pressure dangerous?

Can cause vessel damage, clots, strokes, heart attacks.

Why is low blood pressure dangerous?

Not enough blood to organs → dizziness, fainting.

How does body respond to high BP?

Vasodilation (widening of vessels).

How does body respond to low BP?

Vasoconstriction (narrowing of vessels).

One key factor that raises blood pressure?

Cholesterol buildup narrowing arteries.

How does blood pressure change through the system?

Decreases from arteries → arterioles → capillaries → veins.

What are the two main blood circulation pathways?

Pulmonary circulation (heart → lungs → heart) and systemic circulation (heart → body → heart).

Function of pulmonary circulation?

Carry deoxygenated blood to lungs, release CO2, pick up O2, return oxygenated blood to left atrium.

Function of systemic circulation?

Carry oxygenated blood to body tissues, return deoxygenated blood to right atrium.

Three special systemic circulations?

Coronary (heart), Renal (kidneys), Portal (digestive organs + liver).

What is plasma?

Liquid portion of blood (92% water) with ions, proteins (antibodies, fibrinogen), nutrients, wastes.

What are erythrocytes (RBCs)?

Biconcave cells without a nucleus, filled with hemoglobin for O2 and CO2 transport.

What protein gives blood its red colour?

Hemoglobin (iron-containing, binds O2 loosely).

What does “oxygenated” mean?

RBCs carry O2, bright red.

What does “deoxygenated” mean?

RBCs release O2, carry some CO2, dark red.

Average lifespan of an RBC?

~120 days; broken down in liver and spleen.

What happens if iron is low?

Iron-deficiency anemia → low hemoglobin, reduced oxygen transport, fatigue.

What is sickle cell anemia?

Abnormal RBC shape blocks flow, causes low O2, organ damage, can be fatal.

What are leukocytes (WBCs)?

Larger, less numerous, nucleated cells for defense against infection.

Two main WBC defense methods?

Phagocytosis of microbes; enzyme production to detoxify harmful substances.

What is pus?

Dead/dying leukocytes, bacteria, and tissue cells at infection site.

What is leukemia?

Cancer of WBCs; uncontrolled production of abnormal cells, prone to infection.

What are platelets (thrombocytes)?

Cell fragments with thromboplastin, clot blood at injury sites.

Steps of blood clotting?

1. Platelets release thromboplastin → 2. Converts fibrinogen to fibrin → 3. Fibrin forms net trapping RBCs → 4. Clot contracts → wound sealed.

Why can clots be dangerous?

Traveling clot may block brain (stroke) or heart (heart attack).

What is cholesterol?

Waxy fat-like substance in membranes, hormones, vitamin D; high levels cause plaque buildup.

What is plaque?

Semi-hardened deposits of cholesterol, fats, and cells inside artery walls.

What are lipoproteins?

Proteins that transport cholesterol and fats in blood.

LDL (“bad cholesterol”)?

Carries cholesterol to body cells; deposits in arteries → plaque.

HDL (“good cholesterol”)?

Carries cholesterol from cells back to liver for excretion.

What is atherosclerosis?

Hardening/narrowing of arteries due to fatty deposits; increases BP, reduces elasticity.

What is angina?

Chest pain from reduced blood flow/oxygen to heart tissue.

What causes a heart attack?

Blockage of coronary artery → death of heart tissue.

What causes a stroke?

Blockage of brain artery → death of brain tissue.

What is an aneurysm?

Weak bulging in artery wall, risk of rupture → internal bleeding, stroke, death.

What is a septal defect?

Hole in heart septum → mixing of oxygenated and deoxygenated blood.

What is valvular heart disease?

Faulty valve doesn’t close properly → backflow, heart works harder.

Pros/cons of artificial valves?

Long-lasting but risk clots.

Pros/cons of tissue valves?

Less clot risk but shorter lifespan.

What is a pathogen?

Disease-causing agent (bacteria, virus, parasite).

How can pathogens enter the body?

Cuts, digestive tract, respiratory tract, reproductive tract, insect vectors (e.g. malaria).

First line of defense (barriers)?

Skin, tears, mucous, cilia, saliva, stomach acid, urine flow.

Second line of defense (non-specific)?

Phagocytic WBCs (neutrophils, monocytes, macrophages), inflammation, fever.

What is phagocytosis?

Process where WBCs engulf and digest microbes.

What causes fever?

Chemicals from WBCs act on hypothalamus; slows microbes, speeds immune response.

Third line of defense (specific)?

Antibody-mediated immunity: antibodies target specific antigens.

What is an antigen?

Foreign molecule on pathogen that triggers immune response.

What is an antibody?

Y-shaped protein made by B cells that binds antigens and neutralizes them.