Cellular Biology and Human Health: Diseases and Prevention

Cellular Components and Their Functions

Lysosome

Features: Lysosomes are vesicles containing substances that digest nutrients.

Function: They break down more complex substances into simpler ones.

Centrosomes

Features: Centrosomes are located near the nucleus and consist of two perpendicular cylinders formed by proteins.

Function: They are involved in cell division and the formation of cilia and flagella.

Understanding Health and Disease

Disease

Definition: A disease occurs when a part of the body is altered and can no longer perform its function properly, leading to dysfunction.

Health

Definition: The World Health Organization (WHO) defines health as a state of complete physical, mental, and social well-being, not merely the absence of disease.

Symptoms

When a person falls ill, they perceive characteristic symptoms of the condition, such as pain, fatigue, or fever.

Factors Influencing Health

Factors that help maintain health and prevent disease include:

• A healthy environment
• Healthy habits and lifestyles
• Heredity
• An effective health system

Types of Diseases

Infectious vs. Non-Infectious Diseases

• Infectious Diseases: Caused by pathogens that enter the body.
• Non-Infectious Diseases: Not caused by microorganisms.

Acute vs. Chronic Diseases

• Acute Diseases: Manifest rapidly and are short-lived, such as the flu.
• Chronic Diseases: Develop slowly and last a long time, such as arthritis.

Endemic, Epidemic, and Pandemic Diseases

• Endemic Diseases: Common and unique to a particular region, such as malaria in tropical areas.
• Epidemic Diseases: Affect a large number of people in a short period, like the flu at certain times of the year.
• Pandemic Diseases: Epidemics that affect many countries or even the entire planet.

Pathogens and Infectious Diseases

Microorganisms that cause infectious diseases include bacteria, fungi, protozoa, and viruses.

Malaria: A Case Study

Malaria is a major infectious disease, posing a significant risk for people traveling to warm climates. It is transmitted by the female Anopheles mosquito. The protozoa responsible for malaria, called Trypanosoma, invade and destroy red blood cells.

Transmission of Infectious Diseases

Infectious diseases can be transmitted through:

• Direct contact
• Inanimate objects
• Contaminated water
• Contaminated food
• Air
• Animal vectors

Human Body Defenses

External Barriers

• Structural: The surface of human skin.
• Biochemical: Tears are a biochemical defense.
• Mechanical: Cilia in the epithelium lining the inside of the human respiratory tract.
• Eco: Escherichia coli is a beneficial bacteria commonly found in the human intestine.

Immune Barriers

The immune system relies on white blood cells:

• Phagocytes: Leukocytes that engulf and kill pathogens through a process called phagocytosis.
• Lymphocytes: Leukocytes that produce specific antibodies for each type of invading organism, which destroy or inactivate the pathogens.