Biology 8: Circulatory System

Biology 8

• The theme for the course is the 5Cs: Competence, Character, Commitment, Collaboration, and Creativity, achieved through academic rigor, growth mindset, and grit.

Unit 2: Life Processes of Living Things - Circulatory System

• The circulatory system transports materials throughout the entire body.
• It carries nutrients, water, oxygen to cells, and removes wastes like carbon dioxide.
• The circulatory system is like a highway that connects all body cells.

Circulatory System Components

• Heart: A muscle responsible for pumping blood.
• Blood: A fluid that transports materials throughout the body.
• Vessels: Conduits that carry blood (arteries, arterioles, veins, venules, capillaries).
  • Arteries carry oxygenated blood away from the heart.
  • Veins carry deoxygenated blood back to the heart.
  • Capillaries connect arteries and veins; allow exchange of substances.

Facts About the Human Heart

• It's a muscle; Size of a fist; weight less than a pound.
• Location: In the thorax, flanked by lungs, rests on the diaphragm.
• Top: base, bottom: apex.
• The heart pumps approximately 2,000 gallons of blood every day.
• Heart rate: typically beats between 60 to 100 times per minute.

Gases Transported by Blood

• Oxygen is vital for respiration and is transported to body cells.
• Carbon dioxide is a waste product, transported away from body cells.

Oxygen-Rich and Oxygen-Poor Blood

• The circulatory system has two types of blood, which do not mix.
• Oxygen-rich blood carries oxygen to body cells.
• Oxygen-poor blood carries carbon dioxide away from body cells.

Heart: The Pump Organ

• The heart is the central organ in the circulatory system.
• It pumps blood throughout the body.

Heart Sides

• The heart has two sides separated by a septum (wall).
• This prevents mixing of oxygen-rich and oxygen-poor blood.

The Heart

• The heart's structure and function are crucial for the circulatory system.
• It's an organ located in the chest.
• It pumps blood throughout the body.

Heart Covering: Pericardium

• The pericardium covers the heart and large blood vessels attached to it.
• It's a protective sac made of connective tissue.
• The pericardium is filled with fluid.

Heart Covering: Visceral and Parietal Pericardium

• Visceral pericardium is the innermost layer, directly on the heart.
• Parietal pericardium is the outer layer, on top of the visceral pericardium.

Heart Walls

• The heart has three layers to protect tissues and assist with function.

Heart Chambers: Atrium and Ventricle

• The heart has four chambers: two atria (upper) and two ventricles (lower).
• The atria receive blood, the ventricles pump blood out of the heart.
• The right and left sides of the heart are separated by the septum (wall).

Heart Chambers: Functions

• The right atrium receives deoxygenated blood from the body and pumps it to the right ventricle.
• The right ventricle pumps deoxygenated blood to the lungs.
• The left atrium receives oxygenated blood from the lungs and pumps it to the left ventricle.
• The left ventricle pumps oxygenated blood to the rest of the body.

Heart Valves

• Atrioventricular (AV) valves: Bicuspid (mitral) valve on left, and tricuspid on right, regulate blood flow between atria and ventricles.
• Semilunar valves (pulmonary and aortic) regulate blood flow out of the ventricles into arteries.

Heart Vessels

• Vena Cava: Large veins that collect deoxygenated blood from the body and deliver it to the right atrium. (Superior and Inferior)
• Pulmonary Artery: Carries deoxygenated blood from the right ventricle to the lungs.
• Pulmonary Vein: Carries oxygenated blood from the lungs to the left atrium.
• Aorta: The largest artery, carrying oxygenated blood from the left ventricle to the body.

Blood Vessels

• Arteries: Carry blood away from the heart; Thick walls to withstand high pressure.
• Capillaries: Tiny vessels connecting arteries to veins; site of gas and nutrient exchange.
• Veins: Carry blood toward the heart; Have valves to prevent backflow.

Blood: The Nutrient Carrier

• Blood is a fluid tissue made of plasma and blood cells.

Blood Components

• Plasma: Straw-colored, mostly water. It carries nutrients, hormones, wastes, and salts.
• Red Blood Cells (Erythrocytes): Most numerous; transport oxygen using hemoglobin.
• White Blood Cells (Leukocytes): Larger; part of the body's immune system, fighting infection.
• Platelets (Thrombocytes): Involved in blood clotting to stop bleeding.

Next Topic

• The next topic is the Respiratory System.

Explore the fascinating components and functions of the circulatory system in our Biology 8 quiz. Learn about the heart, blood, and blood vessels, and how they work together to transport essential materials throughout the body. Engage with key concepts such as oxygenated and deoxygenated blood in this exciting unit.