Success Criteria

1. Describe the components of the human circulatory system and their functions.

2. Explain general functions of the heart and blood vessels.

3. Draw and label parts of the human circulatory system.

4. Explain general blood circulation in the body.

5. Describe functions of components of blood.

6. Describe types of bleeding and their control.

Circulatory System Overview

The human circulatory system is divided into:

• Blood Circulatory System

• Lymph Circulatory System

Functions:

• Supply raw materials (e.g., oxygen, glucose).

• Remove waste products (e.g., carbon dioxide, urea).

• Defend against pathogens.

General Functions of the Circulatory System (Blood)

• Transport oxygen from lungs to tissues.

• Transport nutrients from the small intestine to tissues.

• Transport hormones from endocrine glands to target organs.

• Remove waste products from the body.

• Protect against infections.

• Maintain homeostasis.

• Regulate body temperature.

Blood Circulatory System Components

1. Heart

2. Blood Vessels

3. Blood

The Human Heart

• A muscular organ that pumps blood throughout the body.

• Made of cardiac muscle that contracts continuously from about four weeks after fertilization until death.

Chambers of the Heart

• Right Auricle: Receives deoxygenated blood.

• Left Auricle: Receives oxygenated blood.

• Right Ventricle: Pumps deoxygenated blood to the lungs.

• Left Ventricle: Pumps oxygenated blood to the rest of the body.

Pericardial Cavity: Contains pericardial fluid to reduce friction.

Types of Blood

• Oxygenated Blood: Bright red, carries oxygen (left side of the heart).

• Deoxygenated Blood: Bluish (dark red), carries little or no oxygen (right side of the heart).

Differences Between Auricles and Ventricles

• Function:

  • Auricles receive blood.

  • Ventricles pump blood.

• Wall Thickness:

  • Auricles have thin walls.

  • Ventricles have thick walls.

Differences Between Right and Left Ventricle

• Right Ventricle: Pumps to the lungs (short distance).

• Left Ventricle: Pumps to the rest of the body (long distance), has thicker walls.

Septum Functions

• Separates the right and left sides of the heart.

• Prevents mixing of oxygenated and deoxygenated blood.

Heart Valves

1. Semi-lunar Valves: Located in the aorta and pulmonary artery.

2. Bicuspid Valve: Between the left atrium and left ventricle.

3. Tricuspid Valve: Between the right atrium and right ventricle.

Function of Valves: Prevent backflow of blood.

Blood Vessels

• Structures through which blood flows. Three types:

1. Arteries

2. Veins

3. Capillaries

Arteries

• Transport blood away from the heart.

• Thick walls, small lumen, no valves.

• High-pressure blood flow.

• Carry oxygenated blood (except pulmonary artery).

Veins

• Transport blood to the heart.

• Thin walls, wide lumen, valves present.

• Low-pressure blood flow.

• Carry deoxygenated blood (except pulmonary vein).

Capillaries

• Smallest blood vessels.

• One cell thick walls, no valves.

• Facilitate exchange of substances between blood and tissues.

• Connect arteries to veins.

Structural Differences Among Arteries, Veins, and Capillaries

• Arteries:

  • Thick walls

  • Narrow lumen

  • No valves

  • Carry oxygenated blood (except pulmonary artery)

• Veins:

  • Thin walls

  • Wide lumen

  • Valves present to prevent backflow

  • Carry deoxygenated blood (except pulmonary vein)

• Capillaries:

  • Very thin walls (one cell thick)

  • No valves

  • Link arteries and veins

  • Site of gas and nutrient exchange

Functional Differences Among Arteries, Veins, and Capillaries

• Arteries:

  • Transport oxygenated blood from the heart

  • Blood is under high pressure and flows in spurts

• Veins:

  • Bring deoxygenated blood to the heart

  • Blood is under low pressure and flows smoothly

• Capillaries:

  • Site of gas exchange (oxygen and carbon dioxide) between blood and tissues

Blood Vessels and Organs

• Coronary Arteries: Supply oxygen and glucose to heart muscles; blood leaves via coronary veins.

• Pulmonary Arteries: Supply lungs with nutrients and hormones; wastes leave via pulmonary veins.

• Renal Arteries and Veins: Transport blood to and from the kidneys for filtration.

• Hepatic Blood Vessels: Transport blood to and from the liver.

Blood Composition

• Blood Cells:

  • Red Blood Cells (RBCs): Contain hemoglobin, lack a nucleus, biconcave shape for oxygen transport.

  • White Blood Cells (WBCs): Defend against infection, contain a nucleus. Includes phagocytes (e.g., neutrophils, monocytes) and lymphocytes (T-cells, B-cells).

  • Platelets: Small fragments that aid in blood clotting.

• Blood Plasma: Clear yellow liquid, 97% water, contains nutrients, hormones, and waste products.

Functions of Blood Components

• Red Blood Cells: Transport oxygen to body cells.

• White Blood Cells: Protect the body against infection.

• Platelets: Help in clotting at wound sites.

• Blood Plasma: Transports blood cells, nutrients, and waste; distributes heat.

Functions of Lymphatic System

• Transport tissue fluid back to blood vessels.

• Transport fats from the intestines.

• Defend the body by destroying pathogens with lymphocytes.

Body Defense Mechanism of Plasma Cells

Plasma cells play a crucial role in the immune response by releasing antibodies that defend against infections. These antibodies function in several ways:

• Neutralization of Toxins: Some antibodies, known as antitoxins, bind to toxins produced by pathogens, neutralizing their harmful effects.

• Destruction of Germs: Antibodies called lysins can dissolve and kill germs directly.

• Prevention of Pathogen Penetration: Agglutinins clean germs by clumping them together, preventing them from entering host cells or reproducing.

Vaccination is the safest method to stimulate white blood cells to produce these antibodies, providing immunity against diseases.

Blood Circulation in the Heart

1. Heart Contraction and Relaxation:

   • Systole: Heart muscles contract, pumping blood.

   • Diastole: Heart muscles relax, allowing blood to fill.

2. Blood Flow:

   • During systole, the right ventricle pumps deoxygenated blood to the lungs via the pulmonary artery, while the left ventricle pumps oxygenated blood to the body through the aorta.

   • During diastole, deoxygenated blood enters the right atrium via the superior and inferior vena cavae, and oxygenated blood returns to the left atrium via the pulmonary veins.

3. Valves:

   • The tricuspid valve opens to let blood from the right atrium into the right ventricle.

   • The bicuspid valve allows blood from the left atrium into the left ventricle.

   • Semi-lunar valves in the pulmonary artery and aorta prevent backflow of blood.

4. Gas Exchange:

   • In the lungs, oxygen diffuses into the blood, while carbon dioxide diffuses out.

Blood Circulation in the Blood Vessels

• Pulse Rate: Systolic and diastolic pressure creates a pulse, primarily detectable in arteries.

• Pressure Differences: Blood pressure is higher in arteries than in veins; arteries have thick, elastic walls to withstand this pressure.

• Veins: Blood in veins is at lower pressure and has valves to prevent backflow.

Double Circulatory System

1. Two Circuits:

   • Pulmonary Circuit: Blood flows from the heart to the lungs and back.

   • Systemic Circuit: Blood flows from the heart to the rest of the body and back.

2. Mass Flow System: Blood flows in one direction through a closed system of vessels, maximizing efficiency.

Problems Associated with the Circulatory System

A. Malnutrition Diseases

• Causes:

  • Iron Deficiency: Leads to reduced hemoglobin and anemia.

  • Protein Deficiency: Impairs red blood cell formation.

  • Vitamin C Deficiency: Causes gum bleeding due to weakened blood vessel walls.

• Infectious Diseases:

  • Bilharzia: Damages blood vessel walls, causing bleeding.

  • Malaria: Destroys red blood cells.

  • Amoebic Dysentery: Causes bleeding in the intestines.

  • Hookworms: Suck blood, leading to intestinal bleeding.

B. Anemia

• Causes:

  • Iron and protein deficiencies.

  • Blood loss from injuries.

Types of Bleeding

1. Arterial Bleeding: Rapid and severe, due to high-pressure blood flow.

2. Venous Bleeding: Slower and less severe.

3. Capillary Bleeding: Minor bleeding, often self-limiting.

Prevention and Treatment of Anemia

• Diet: Consume iron and protein-rich foods.

• Medication: Supplements and treatments.

• Infection Control: Timely treatment of infections like malaria.

• Blood Transfusion: Replenish lost blood volume.

• Vitamin C Intake: Supports blood vessel health.