Human Reproductive Health: Systems, Contraception, and STIs
Human Reproductive Systems
The human reproductive system is a complex biological system responsible for sexual reproduction. Understanding its components and processes is fundamental to comprehending human biology and health.
Fundamentals of Human Reproduction
Gametes and Chromosomes
- Gametes: These are reproductive cells (eggs and sperm) that contain half of the genetic material necessary to form a new organism, enabling sexual reproduction.
- Number of Chromosomes: Humans have 46 chromosomes (23 pairs). Gametes contain 23 chromosomes, one from each pair.
Sexual Reproduction and Species Types
- Sexual Reproduction: Involves the union of gametes from two individuals, promoting genetic variability and evolution.
- Unisexual Species: Have only one sex, either male or female, and reproduce through asexual methods or by reproduction with individuals of the opposite sex.
- Species with Sexual Dimorphism: Exhibit noticeable physical differences between males and females, such as size or secondary sexual characteristics like pubic or facial hair.
Reproductive Cycles
The human reproductive process involves complex cycles in both males and females, typically discussed over a 28-day cycle for females.
Ovarian Cycle (Days 1-28)
- Follicle Maturation (Days 1-14): The developing follicle prepares to ovulate, with an increase in estrogen levels.
- Ovulation (Around Day 14): Release of the mature egg from the follicle.
- Formation of the Corpus Luteum (Days 14-28): The emptied follicle transforms into the corpus luteum, which produces progesterone to prepare the uterus.
Uterine Cycle (Days 1-28)
- Menstruation (Days 1-5): Shedding of the endometrium if there is no pregnancy.
- Proliferative Phase (Days 6-14): The endometrium reappears and thickens under the stimulation of estrogen.
- Secretory Phase (Days 15-28): The endometrium prepares for implantation, stimulated by progesterone.
Female Reproductive System
Functions and Parts
- Vulva: External organs, including the labia majora and minora.
- Hymen: Thin membrane that partially covers the vagina.
- Vagina: Canal connecting the uterus to the outside.
- Uterus: Organ where pregnancy develops.
- Cervix: Lower part of the uterus connecting to the vagina.
- Endometrium: Inner mucosa that renews during the cycle.
- Fallopian Tubes: Conduct the egg from the ovaries to the uterus.
- Ovaries: Produce eggs and hormones.
- Clitoris: Erectile organ with a function associated with the nervous system and pleasure circuits, making copulation feel pleasurable from an evolutionary perspective and helping to perpetuate the species.
- Mons Pubis: Fatty area above the pubis where pubic hair grows, serving as a protective barrier for female sexual organs.
- Bartholin’s Glands: Secrete lubrication into the vagina.
Male Reproductive System
Functions and Parts
- Testicles: Produce sperm and testosterone.
- Epididymis: Stores and matures sperm.
- Scrotum: Sac that surrounds and protects the testicles.
- Vas Deferens: Transports sperm.
- Prostate: Secretes fluid that is part of semen.
- Cowper’s Glands: Secrete pre-seminal fluid.
- Urethra: Tube passing through the penis, transports semen and urine (not at the same time).
- Penis: Copulatory and urinary organ.
- Corpora Cavernosa: Erectile tissues of the penis that cause erection when blood enters and stay erect for a period. After ejaculation, the penis becomes flaccid again, returning to normal state.
Contraceptive Methods
Contraceptive methods are designed to prevent pregnancy. Their effectiveness varies significantly, and not all methods protect against sexually transmitted infections (STIs).
Natural Methods
Based on controlling biological processes, these methods offer an extremely low pregnancy prevention rate, often less than 25-30% effective.
- Ogino Method (Rhythm Method): Abstinence during fertile days, based on calendar tracking. Protects only against pregnancy.
- Coitus Interruptus (Withdrawal Method): Removing the penis before ejaculation. Only prevents pregnancy, not STIs.
- Basal Body Temperature Method: Monitoring changes in body temperature to identify fertile days. Only contraceptive, no STI protection.
Physical Barrier Methods
These methods present a physical barrier that prevents sperm from reaching the egg, thereby preventing fertilization and pregnancy.
- Male and Female Condoms: Physical barriers, usually made of latex, protecting against both pregnancy and STIs.
- IUD (Intrauterine Device): Prevents pregnancy, but does not protect against STIs.
- Diaphragm: A physical barrier preventing pregnancy, with no STI protection.
Chemical and Hormonal Methods
These methods simulate ovarian or uterine hormonal cycles by releasing sex hormones, providing false signals to the ovary or uterus, preventing egg proliferation, release, or implantation.
- Contraceptive Pill, Ring, and Hormonal Patch: Prevent pregnancy, but do not protect against STIs.
Surgical Methods
Based on operations on the reproductive organs, these methods prevent gamete release and are generally permanent.
- Tubal Ligation (Female Sterilization): Involves operations on the Fallopian Tubes. Prevents pregnancy, no STI protection.
- Vasectomy (Male Sterilization): Involves operations on the Vas Deferens (seminal tube). Prevents pregnancy, no STI protection.
Sexually Transmitted Infections (STIs)
STIs are transmitted through direct contact with secretions contaminated with bodily fluids or sexual contact with contaminated sexual fluids (semen, vaginal secretions, urine, blood, or saliva). These infections are caused by various pathogens, including viruses, bacteria, fungi, or arthropods.
Common STI Pathogens and Conditions
- HIV (Human Immunodeficiency Virus): Causes AIDS.
- Syphilis: Caused by the bacterium Treponema pallidum.
- Gonorrhea: Caused by the bacterium Neisseria gonorrhoeae.
- Herpes: Caused by the Herpes Simplex Virus.
- HPV (Human Papillomavirus): A common viral infection.
- Hepatitis: Viruses affecting the liver (e.g., Hepatitis B, which can be sexually transmitted).
- Candidiasis: A fungal infection caused by Candida albicans.
- Pubic Lice: Parasites living in the pubic area.
Preventing STIs and Contagious Diseases
Adopting healthy habits is crucial for preventing the spread of STIs and other contagious diseases.
- Use contraceptive methods like condoms to avoid risky relationships.
- Maintain proper personal hygiene.
- Limit the number of sexual partners.
- Undergo regular medical testing.
- Get vaccinated against Hepatitis B and HPV.
- Avoid sharing personal objects.
- Engage in consensual and safe sexual activities.
Skin Conditions and Diseases
Skin disorders are numerous and can range from common infections to serious conditions like cancer.
Common Skin Disorders
Skin Cancer
Characterized by malignant spots that grow and may form tumors and other complications. These are often accelerated by prolonged exposure to sunlight without proper sun protection. It is advisable to avoid excessive sun exposure and protect the skin during peak sunlight hours.
Fungal and Bacterial Infections
Can cause various skin problems, changing skin color and producing foul odors. These are mainly spread through contact with infected persons or contaminated environments like swimming pools, communal showers, gyms, and humid, warm places. Proper hygiene is essential to prevent contagion, such as avoiding walking barefoot on wet surfaces near pools to prevent conditions like athlete’s foot.
Sensory Receptors and Taste
Our senses allow us to interact with the world, and taste is a crucial one, primarily detected by chemoreceptors.
Taste Perception
Responsible for detecting flavors through the chemoreceptors on the tongue’s papillae. It recognizes five basic tastes: sweet, salty, sour, bitter, and umami. Spiciness is not a taste but an aroma; the burning sensation from spicy foods results from activation of thermoreceptors that sense high temperatures, causing a burning sensation in the throat.
Taste Impairments and Alterations
Main taste impairments involve partial or total loss of chemoreceptors (e.g., loss of sensitivity due to COVID-19) or the appearance of bumps in the mouth caused by viruses, bacteria, fungi, or other microorganisms. These microorganisms can lead to bumps, wounds, inflammation, and other issues.