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Biology 8 - Science and Health

• The theme for this class is the 5C's (Competence, Character, Commitment to Achieve, Collaboration, Creativity) through academic rigor, growth mindset, and grit.

Unit 2: Life Processes of Living Things - Circulatory System

• The circulatory system moves materials throughout the body.
• It carries nutrients and water to cells, and removes wastes like carbon dioxide.
• The system acts like a highway, connecting all body cells.

Introduction of Circulatory System

• The circulatory system ensures efficient transport of essential elements.
• This system has no mixing of oxygen-rich and oxygen-poor blood.

Components of Circulatory System

• Heart
• Blood
• Blood vessels (arteries, arterioles, veins, venules, capillaries)

Heart Facts

• The heart is a muscle.
• It pumps approximately 2,000 gallons of blood daily.
• It beats between 60 to 100 times per minute.
• The heart has a pericardium, a protective sac of connective tissue, filled with fluid.

Gases Transported in the Circulatory System

• The blood transports oxygen for cellular respiration.
• It carries away carbon dioxide produced by cells

Types of Blood

• Oxygen-rich blood: Travels to body cells, high oxygen, low carbon dioxide.
• Oxygen-poor blood: Travels away from body cells, low oxygen, high carbon dioxide.

Heart Sections

• The heart is divided into two sections to keep oxygen-rich and oxygen-poor blood separate.
• Each section contains an atrium (receives blood) and a ventricle (pumps blood).

Heart Covering

• The pericardium covers the heart and large blood vessels attached to it.
• It's a protective sac of connective tissue surrounding the heart.
• Filled with a fluid.
• The innermost layer is called the visceral pericardium and is directly on the heart.
• The outer layer is called the parietal pericardium.

Heart Walls

• Epicardium: Outermost layer, fat cushions the heart.
• Myocardium: Middle layer, mainly cardiac muscle for contractions. Electrical conductivity similar to nerves. Blood supply from coronary arteries.
• Endocardium: Innermost layer, thin and smooth, stretches during heart pumping.

Heart Chambers

• Atria: Upper chambers that receive blood into the heart.
• Ventricles: Lower chambers that pump blood out of the heart.
• Septum: Wall between the right and left sides, preventing mixing of oxygenated and deoxygenated blood.

Right Atrium

• Receives deoxygenated blood from the superior vena cava.
• Pumps blood into the right ventricle.

Right Ventricle

• Receives deoxygenated blood from the right atrium.
• Pumps blood into the pulmonary artery.

Left Atrium

• Receives oxygenated blood from pulmonary veins.
• Pumps blood into the left ventricle.

Left Ventricle

• Receives oxygenated blood from the left atrium.
• Pumps blood into the aorta.

Heart Valves

• Atrioventricular (AV) valves: Bicuspid (mitral) valve (left side) and Tricuspid valve (right side), control blood flow between atria and ventricles, preventing backflow.
• Semilunar valves: Pulmonary valve (right side) and Aortic valve (left side), control blood flow from ventricles to arteries, preventing backflow.

Heart Vessels

• Vena Cava (Superior and Inferior): Large veins that carry deoxygenated blood to the right atrium.
• 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: Largest artery, carries oxygenated blood from the left ventricle to the body.

Blood Vessels (Arteries, Veins, Capillaries)

• Arteries: Carry blood away from the heart, with thick walls to withstand high pressure.
• Capillaries: Tiny vessels connecting arterioles to venules, thin walls for efficient gas and nutrient exchange with tissues.
• Veins: Carry blood towards the heart. Walls are thinner than arteries, contain one-way valves.

Blood

• Plasma: Liquid component of blood, 90% water, containing dissolved gases, salts, nutrients, enzymes, hormones, wastes, and proteins.
• Blood cells: Red blood cells (transport oxygen), white blood cells (fight infection), and platelets (blood clotting).

Red Blood Cells

• Called erythrocytes, most numerous.
• Transport oxygen throughout the tissues.
• Contain haemoglobin, which bonds with oxygen to form oxyhaemoglobin.
• Disc-shaped, made in red bone marrow; circulate for 120 days.

White Blood Cells

• Called leukocytes, larger than red blood cells.
• Part of the body's defense system.
• Defend against infection, fight parasites, attack bacteria.
• Some white blood cells surround and consume harmful microbes.
• Some produce antibodies that fight infection.

Platelets

• Formed in red bone marrow, involved in blood clotting.
• Help repair tissues and close wounds.
• Form a plug over wounds when needed.

Blood Circulation

• Coronary Circulation (Blood supply to heart muscle).
• Pulmonary Circulation (Blood flow to lungs for oxygenation).
• Systemic Circulation (Blood flow to body tissues).

Blood Pressure

• Blood pressure is the force of blood against the artery walls.
• Systolic pressure: Pressure when ventricles contract.
• Diastolic pressure: Pressure when ventricles relax.
• Blood pressure is measured in millimeters of mercury (mmHg).

Diseases in the Circulatory System

• Atherosclerosis: Narrowing of arteries due to plaque build-up.
• Coronary Artery Disease: Atherosclerosis affects arteries supplying heart muscle.
• Varicose Veins: Swollen and twisted veins, commonly in legs.
• Rheumatic Heart Disease: Inflammatory disease damaging heart valves.
• Congenital Heart Disease: Defect present at birth.
• Anemia: Body lacks enough red blood cells.
• Leukemia: Body produces too many white blood cells.
• Hemophilia: Inherited disease preventing proper blood clotting.