By jhoony sins 
Great — here’s an overview of sex from a biological perspective, covering anatomy, reproduction, and related systems:
1. Biological Purpose of Sex
In biology, sex refers to the process by which organisms reproduce and pass on their genetic material. Sexual reproduction involves the combination of genetic material from two parents, resulting in offspring that are genetically unique. This promotes genetic diversity, which is crucial for the survival and evolution of species.
2. Sexual Reproduction
Sexual reproduction generally involves:
- Gametes: Specialized reproductive cells — sperm (male) and egg/ovum (female).
- Fertilization: The union of a sperm and egg to form a zygote, which develops into a new organism.
In humans:
- Sperm is produced in the testes.
- Eggs are produced in the ovaries.
- Fertilization typically occurs in the fallopian tube.
3. Human Sexual Anatomy
Male Reproductive System
- Penis: External organ for delivering sperm.
- Testes: Produce sperm and testosterone.
- Scrotum: Sac that holds the testes and regulates temperature.
- Epididymis: Stores mature sperm.
- Vas deferens: Transports sperm from the epididymis to the urethra.
- Seminal vesicles, prostate, bulbourethral glands: Produce fluids that nourish and transport sperm (semen).
Female Reproductive System
- Vagina: Canal leading to the uterus, receives sperm.
- Cervix: Lower part of the uterus that opens into the vagina.
- Uterus: Where a fertilized egg implants and grows during pregnancy.
- Fallopian tubes: Where fertilization usually occurs.
- Ovaries: Produce eggs and hormones like estrogen and progesterone.
4. Hormonal Regulation
Sexual development and reproduction are controlled by hormones:
- Testosterone (primarily in males): Drives development of male traits and sperm production.
- Estrogen and progesterone (primarily in females): Regulate the menstrual cycle and pregnancy.
- LH (luteinizing hormone) and FSH (follicle-stimulating hormone) control gamete production in both sexes.
5. The Menstrual Cycle
In females, the body prepares for potential pregnancy every month:
- Ovulation: Release of an egg from the ovary.
- Menstruation: Shedding of the uterine lining if fertilization does not occur.
6. Fertilization and Development
- After fertilization, the zygote undergoes rapid cell division (cleavage) and becomes a blastocyst.
- The blastocyst implants in the uterine wall and develops into an embryo, then a fetus.
- Pregnancy lasts ~9 months, culminating in childbirth.
7. Sexual Dimorphism
In many species (including humans), males and females have distinct physical characteristics beyond reproductive organs, influenced by sex hormones — such as body size, voice pitch, and body hair.