Human Reproduction » Reproductive System Structure

What you'll learn this session

Study time: 30 minutes

Structure and function of the male reproductive system
Structure and function of the female reproductive system
How reproductive organs work together
Key hormones involved in reproduction
How to identify reproductive structures on diagrams

Introduction to Human Reproductive Systems

The human reproductive system is designed to produce offspring through sexual reproduction. Males and females have different reproductive organs that work together during reproduction. Understanding these structures is essential for comprehending how humans reproduce and how life begins.

Key Definitions:

Reproduction: The biological process by which new individual organisms are produced.
Gametes: Sex cells (sperm in males, eggs in females) that contain half the normal number of chromosomes.
Gonads: Organs that produce gametes (testes in males, ovaries in females).
Fertilisation: The fusion of male and female gametes to form a zygote.

👨 Male Reproductive System

The male reproductive system is designed to produce, store and deliver sperm to fertilise a female egg.

👩 Female Reproductive System

The female reproductive system is designed to produce eggs, receive sperm, allow fertilisation and support the development of a foetus.

Male Reproductive System

The male reproductive system consists of both external and internal organs that work together to produce sperm and deliver it during sexual intercourse.

External Male Reproductive Organs

The external male reproductive organs include:

💎 Penis

Structure: Cylindrical organ composed of erectile tissue.

Function: Delivers sperm into the female reproductive tract during sexual intercourse. The tip (glans) is covered by the foreskin (prepuce), which can be removed by circumcision.

🍊 Scrotum

Structure: External sac of skin and muscle that hangs below the penis.

Function: Houses the testes and keeps them at a temperature about 2-3°C below body temperature, which is optimal for sperm production.

Internal Male Reproductive Organs

The internal male reproductive organs work together to produce, nourish and transport sperm:

🍇 Testes

Structure: Pair of oval-shaped organs inside the scrotum.

Function: Produce sperm (in seminiferous tubules) and testosterone (by Leydig cells).

📑 Epididymis

Structure: Coiled tube attached to each testis.

Function: Stores immature sperm while they mature and become motile.

🔗 Vas Deferens

Structure: Long, muscular tube extending from the epididymis.

Function: Transports mature sperm from the epididymis to the urethra.

💦 Seminal Vesicles

Structure: Pair of glands behind the bladder.

Function: Produce fluid rich in fructose (energy for sperm) that makes up about 60% of semen volume.

🍒 Prostate Gland

Structure: Walnut-sized gland below the bladder.

Function: Produces alkaline fluid that neutralises the acidic environment of the vagina, protecting sperm.

Did You Know? 💡

A healthy adult male can produce around 1,500 sperm cells per second, which is about 130 million per day! Each sperm is just 0.05 millimetres long, but contains all the genetic information needed from the father to create a new human being.

Female Reproductive System

The female reproductive system is more complex than the male system as it not only produces gametes but also provides a place for fertilisation and foetal development.

External Female Reproductive Organs

The external female reproductive organs are collectively known as the vulva and include:

📸 Labia

Structure: Two pairs of skin folds (labia majora and labia minora) that protect the vaginal opening.

Function: Provide protection for the internal reproductive organs.

🌸 Clitoris

Structure: Small, sensitive organ at the front of the vulva.

Function: Primarily associated with sexual pleasure, contains many nerve endings.

Internal Female Reproductive Organs

The internal female reproductive organs work together to produce eggs, facilitate fertilisation and support pregnancy:

🍑 Ovaries

Structure: Pair of almond-shaped organs in the pelvic cavity.

Function: Produce eggs (ova) and hormones (oestrogen and progesterone).

🔮 Fallopian Tubes

Structure: Pair of tubes extending from the uterus toward the ovaries.

Function: Transport eggs from the ovaries to the uterus; site of fertilisation.

🏠 Uterus

Structure: Pear-shaped, muscular organ in the pelvic cavity.

Function: Houses and nourishes the developing embryo/foetus during pregnancy.

👉 Cervix

Structure: Lower, narrow portion of the uterus that connects to the vagina.

Function: Produces mucus that helps sperm travel into the uterus; dilates during childbirth.

🔍 Vagina

Structure: Muscular canal extending from the vulva to the cervix.

Function: Receives sperm during sexual intercourse; serves as the birth canal during childbirth.

Case Study Focus: Menstrual Cycle

The female reproductive system undergoes a monthly cycle called the menstrual cycle. This cycle prepares the body for potential pregnancy each month. If fertilisation doesn't occur, the lining of the uterus (endometrium) is shed during menstruation. The average cycle lasts 28 days, but can range from 21-35 days. Understanding this cycle is crucial for comprehending female fertility and reproductive health.

Comparing Male and Female Reproductive Systems

While the male and female reproductive systems have different structures, they share some common features and functions:

⚖ Similarities

Both produce gametes (sex cells)
Both have gonads that produce hormones
Both have ducts to transport gametes
Both are controlled by hormones from the pituitary gland

≠ Differences

Males produce millions of small, motile sperm; females produce one large, non-motile egg at a time
Male systems are primarily external; female systems are primarily internal
Female systems have structures to support embryo/foetal development
Female systems undergo cyclical changes (menstrual cycle)

Key Hormones in Reproduction

Hormones play a crucial role in controlling reproductive functions:

👨 Male Hormones

Testosterone: Produced by the testes, responsible for male secondary sexual characteristics and sperm production.
FSH (Follicle Stimulating Hormone): Stimulates sperm production.
LH (Luteinising Hormone): Stimulates testosterone production.

👩 Female Hormones

Oestrogen: Produced by the ovaries, responsible for female secondary sexual characteristics and regulation of the menstrual cycle.
Progesterone: Prepares the uterus for pregnancy and maintains pregnancy.
FSH: Stimulates egg development in the ovaries.
LH: Triggers ovulation (release of an egg).

Exam Tip ✍

When studying diagrams of reproductive systems, focus on both the structure and function of each part. Examiners often ask you to label diagrams or explain how specific structures contribute to reproduction. Remember that understanding the relationship between structure and function is key to scoring high marks!

🧠 Test Your Knowledge!