Heart Valves and Blood Flow

• Atrioventricular (AV) valves are located between the atria and ventricles.

Tricuspid Valve

• Located on the right side of the heart.
• Allows blood flow from the right atrium to the right ventricle.
• Prevents backflow when the ventricle contracts.

Mitral Valve

• Also known as the bicuspid valve, located on the left side of the heart.
• Allows blood flow from the left atrium to the left ventricle.
• Prevents backflow when the ventricle contracts.

Pulmonary Semilunar Valve

• Located between the right ventricle and the pulmonary artery.
• Opens to allow blood to flow from the right ventricle into the lungs.
• Closes to prevent blood from flowing back into the heart.

Aortic Semilunar Valve

• Located between the left ventricle and the aorta.
• Opens to let blood flow from the left ventricle into the aorta, which sends blood to the rest of the body.
• Closes to stop blood from flowing back into the heart.

Right Side of Heart

• Receives deoxygenated blood from the body.
• Sends blood to the lungs to get oxygen and remove carbon dioxide.

Left Side of Heart

• Receives oxygen-rich blood from the lungs.
• Pumps oxygenated blood to the body.

Pulmonary Circulation

• Carries blood from the heart to the lungs and back.
• Blood picks up oxygen and drops off carbon dioxide in the lungs.

Systemic Circulation

• Carries oxygen-rich blood from the heart to the body and back.
• Delivers oxygen to the body and brings back carbon dioxide.

Vascular System

• Arteries carry blood away from the heart.
• Veins carry blood back to the heart.
• Capillaries are tiny vessels where oxygen and nutrients move into the body’s tissues.

Blood Components

• Red blood cells carry oxygen.
• White blood cells fight infections.
• Platelets help stop bleeding (clotting).
• Plasma is the liquid that carries everything.

Supplying the Heart with Blood

• Right and left coronary arteries supply oxygen-rich blood to the heart muscle (myocardium).
• Arteries branch into arterioles, then capillaries.
• There are 3000 to 4000 capillaries in 1 square millimeter of heart muscle.

Capillary Function

• Oxygen and nutrients move into the heart muscle.
• Carbon dioxide and waste move out of the heart muscle.
• Blood collects into coronary venules, then coronary veins, then the coronary sinus.
• The coronary sinus empties into the right atrium of the heart.

Myocardium

• The muscle part of the heart that pumps.
• Muscle cells are connected and share electrical signals, contracting together.

Heart Contraction Electrical Signals

• Special cells send and receive electric signals.
• Signals start at the SA node (Sinoatrial Node), the pacemaker.

SA Node and Heart Rate

• The SA node tells the heart to beat 70–80 times per minute.
• If the SA node is broken, the AV node takes over.
• The autonomic nervous system can speed up or slow down heart rate.

Heart Contraction Pathway

• The autonomic nervous system sends a signal to the SA node.
• The SA node sends an electrical signal through the atria, causing them to contract from top to bottom, pushing blood into the ventricles.
• The signal reaches the AV node, which passes it down the Bundle of HIS, which is insulated.
• The signal travels to the bottom of the heart into the Purkinje fibers, which are not insulated.
• The Purkinje fibers make the ventricles contract from bottom to top, pushing blood out of the heart.

Blood Composition

• 55% Plasma (liquid part)
• 45% Blood Cells (red, white, and platelets)

Plasma Composition

• 90% water
• 7% proteins (like albumin)
• 3% other stuff (acids, salts, nutrients, and waste)

Types of Blood Cells

• Red Blood Cells (RBCs) make up 99% of all blood cells and contain hemoglobin.
• Hemoglobin carries oxygen to your body and carbon dioxide to your lungs.
• White Blood Cells (WBCs) make up less than 1% of blood cells and fight infections and diseases.
• Platelets are also less than 1% and help blood clot.

The Quantity of Blood

• Blood is about 8% of body weight.
• A 70 kg person has about 5.6 Liters of blood.

Blood Types

• Blood type is based on antigens on the surface of red blood cells.

Main Blood Groups

• Group A has A antigens.
• Group B has B antigens.
• Group AB has both A and B antigens.
• Group O has no A or B antigens.

Rh Factor

• If you have Rh, your blood is Rh+ (positive).
• If you don’t have Rh, your blood is Rh− (negative).
• For example, blood type A with Rh is A+, without Rh is A−.

Blood Transfusions

• O can only get from O.
• A can get from A and O.
• B can get from B and O.
• AB can get from A, B, AB, O (universal receiver).

Blood Donation

• O can donate to everyone (universal donor).
• A can donate to A and AB.
• B can donate to B and AB.
• AB can only donate to AB.

Cardiac Cycle

• Systole is when the heart contracts and pushes blood out.
• Diastole is when the heart relaxes and fills with blood.

Blood Pressure

• Systolic Pressure is the pressure when the heart contracts (top number).
• Diastolic Pressure is the pressure when the heart relaxes (bottom number).
• Example: 120/80 mmHg means 120 pressure when the heart squeezes, 80 pressure when the heart relaxes.

Cardiac Output

• Cardiac Output = Stroke Volume × Heart Rate.
• Stroke Volume is how much blood is pumped with one beat.
• Heart Rate is how many times your heart beats in one minute.
• Example: Stroke Volume = 70 mL, Heart Rate = 75 beats/minute → Cardiac Output = 70 × 75 = 5250 mL/min or 5.25 L/min.

Physiological Adaptation

• A short-term change the body makes when facing something new or challenging.
• The body adapts to stress to become stronger and more efficient.

Cardiovascular Adaptations to Exercise

• Increase in Red Blood Cells (Erythrocytes).
• More red blood cells mean more oxygen can be delivered to your muscles for more energy and less fatigue.
• Enhanced waste removal means less lactic acid buildup.

Increased Capillaries

• More capillaries mean better oxygen delivery and waste removal.
• Muscles get fresher blood faster and recover quicker.

Greater Venous Return

• More blood is sent back to the heart after going through the body.
• Helps the heart send more oxygen to the muscles and take waste out faster.

Stronger Heart Contractions

• The heart pumps harder and pushes more blood out with each beat.
• This increases stroke volume and cardiac output
• Heart rate gets lower.

More Platelets

• The body is better at repairing injuries from training.
• It helps you recover faster and train again sooner.

Overall Effects of Training

• More energy.
• Less soreness.
• Faster recovery.
• Lower heart rate.
• More endurance.