Menstrual Cycle Phases and Infectious Diseases

Menstrual Cycle Phases

• Proliferative phase: The mucous membrane of the uterus, called the endometrium, builds up. This phase is initiated by estrogens (produced by the ovaries). It lasts approximately 11 days.
• Luteal phase: The endometrium reaches its maximum thickness and prepares to receive and nourish an embryo. This phase is initiated by progesterone (released by the corpus luteum of the ovaries). It lasts approximately 12 days, until the hormone ceases production. If an embryo is present (if an egg has been fertilized), the corpus luteum continues to secrete progesterone.
• Menstruation: This phase only occurs when there is no embryo. The ovaries secrete significantly lower levels of hormones. Consequently, the endometrium, now quite thick and highly vascularized, detaches and is expelled from the body (via the vagina) along with some blood.

Microorganisms Causing Infectious Diseases

• Pathogenic bacteria: These single-celled prokaryotes can cause diseases directly or through toxins they produce.
• Pathogenic Fungi: These are heterotrophic eukaryotes. Some are single-celled, while others are multicellular. They thrive in damp areas and cause fungal infections.
• Pathogenic Protozoa: These are single-celled eukaryotes. Some are parasitic, while others live freely in water.
• Pathogenic Viruses: Viruses are non-cellular. They are not truly living organisms. To reproduce, they must enter the cell of a living thing, where they act as parasites.

Types of Diseases

By Origin

• Infectious: Caused by pathogenic microorganisms (e.g., rabies, measles).
• Non-infectious: Not caused by pathogenic microorganisms (e.g., gout, depression).

By Appearance and Duration

• Acute: Manifests quickly and lasts a short time (e.g., flu).
• Chronic: Manifests slowly and lasts a long time (e.g., arthritis).

By Incidence in the Population

• Sporadic: Very few cases occur in the population (e.g., strokes).
• Endemic: Common and exclusive to a specific region (e.g., malaria).
• Epidemic: Affects many people in a short period (e.g., the flu at certain times of the year).
• Pandemic: An epidemic that spreads to many countries worldwide (e.g., AIDS).