Circulatory System Overview

Circulatory System

• The circulatory system is responsible for transporting blood throughout the body.
• Consists of a pump (heart), tubes (blood vessels), and a liquid (blood).
• Valves in the heart and blood vessels ensure blood flows in the correct direction.

The Heart

• The heart’s function is to pump blood around the body.
• The heart is composed of cardiac muscle, allowing it to contract and relax continuously throughout life.
• The heart has four chambers: right atrium, left atrium, right ventricle, and left ventricle.

Heart Valves

• Four valves regulate blood flow within the heart:
  • Aortic (semilunar) valve
  • Pulmonary valve
  • Tricuspid valve
  • Bicuspid/mitral valve

Circulatory Systems

• Double circulatory system: Blood passes through the heart twice during a complete body circuit. Found in mammals, birds, and reptiles.
• Single circulatory system: Blood passes through the heart once during a complete body circuit. Found in fish.

Systemic and Pulmonary Systems

• Systemic system: Blood vessels transporting blood to the rest of the body and back.
• Pulmonary system: Blood vessels transporting blood to the lungs and back.

Blood Flow Through the Heart

• Deoxygenated blood: Enters the right atrium through the vena cava, travels to the right ventricle, and is pumped to the lungs via the pulmonary artery.
• Oxygenated blood: Returns from the lungs to the left atrium via the pulmonary veins, then to the left ventricle, and is pumped throughout the body via the aorta.

Coronary Arteries

• Coronary arteries supply nutrients and oxygen to the heart muscle.
• The heart muscle requires a continuous supply of nutrients and oxygen to maintain contraction and relaxation.

Heart Chambers

• Ventricles: Pump blood out of the heart (thicker walls than atria).
• Atria: Receive blood flowing into the heart.
• Right ventricle: Pumps deoxygenated blood to the lungs.
• Left ventricle: Pumps oxygenated blood to the rest of the body.

Coronary Heart Disease (CHD)

• CHD is a blockage of the coronary arteries.
• A blocked coronary artery can lead to a heart attack (cardiac arrest).
• Factors increasing CHD risk include smoking, diet, obesity, stress, and genetics.

Preventing and Treating CHD

• Prevention: Exercise, stop smoking, avoid diets high in animal fats.
• Treatment: Medications (statins, propanolol, warfarin), surgery (coronary bypass, angioplasty), heart transplant.

Heart Beat and ECG

• Heart beat: Caused by the expansion and relaxation of arteries due to blood pressure.
• Normal heart rate: 60-75 beats per minute.
• ECG (electrocardiography): Records the electrical activity of the heart.
• SA node (sinoatrial node): Responsible for generating electrical impulses that control the heart's rhythm.

Blood Vessels

• Arteries: Thick, elastic walls to withstand high blood pressure.
• Veins: Thinner, less elastic walls, have valves to prevent backflow.
• Capillaries: Thin, narrow vessels for exchange of nutrients, oxygen, and waste products between blood and tissues.

Blood Components

• Plasma: Liquid component of blood, contains proteins, nutrients, hormones, and waste products.
• Red blood cells (RBCs): Contain hemoglobin for carrying oxygen.
• White blood cells (WBCs): Fight infections and remove dead cells.
• Platelets: Involved in blood clotting.

Red Blood Cells

• Produced in bone marrow.
• Have a short lifespan (around 4 months).
• Contain hemoglobin, a protein carrying oxygen.
• Biconcave disc shape maximizes surface area for oxygen absorption and release.
• Lack a nucleus.

White Blood Cells

• Have a nucleus for cellular functions.
• Larger than red blood cells, often have a lobed nucleus.
• Involved in fighting infections and removing dead cells.
• Can squeeze out of capillaries to reach infection sites.
• Produce antibodies.

Platelets

• Small, non-nucleated fragments of cells.
• Produced in red bone marrow.
• Crucial for blood clotting to prevent excessive blood loss and stop pathogens from entering the body through wounds.

Blood Clotting

• Involves a complex cascade of events:
  • Platelets stick to the damaged blood vessel wall.
  • A mesh of protein fibers forms, trapping blood cells to create a clot.
  • The clot stops further bleeding.

Explore the essential components and functions of the circulatory system, including the heart, blood vessels, and the vital role of valves. This quiz delves into the complexities of both double and single circulatory systems in various organisms. Test your knowledge on how blood circulates through the body and the anatomy of the heart.