How do Organisms Reproduce? · Lesson 11 of 14
Male Reproductive System
“Sperm production needs a cool workplace and a carefully connected route.”
• Identify the main male reproductive organs. • Explain why testes lie in the scrotum. • Describe sperm production and testosterone function. • Trace sperm through the reproductive tract. • Explain the roles of seminal vesicles and prostate. • Relate sperm structure to movement.
The male reproductive system must produce germ cells, support them in a fluid and deliver them toward the site of fertilisation. Different organs specialise in these connected tasks.
Testes And Scrotum
Sperms form in the testes. The testes lie in the scrotum outside the abdominal cavity because sperm production requires a temperature slightly below core body temperature. Testes also produce testosterone, which supports sperm formation and pubertal changes.
Testosterone is a reproductive hormone produced mainly by the testes that helps regulate sperm formation and male pubertal changes.
Transport And Supporting Secretions
Sperm travel from each testis through the vas deferens. Secretions from seminal vesicles and the prostate join them, forming a fluid that supports movement and provides nutrients. The vas deferens joins the urethra, which carries semen through the penis. Urine and semen share this passage but normally do not pass through it simultaneously.
| Part | Function |
|---|---|
| Testes | Produce sperm and testosterone |
| Scrotum | Maintains a cooler environment for sperm formation |
| Vas deferens | Carries sperm |
| Seminal vesicles | Add nutrient-rich fluid |
| Prostate gland | Adds fluid supporting sperm transport |
| Urethra | Common exit passage at different times |
| Penis | Transfers semen into the female reproductive tract |
Structure Of Sperm
A sperm is a microscopic motile cell. Its head contains hereditary material, a middle region supplies energy for movement, and its tail propels it through fluid toward the egg. Sperm contribute hereditary information; they do not carry a large food store for the embryo.
Problem
Trace sperm from production to exit.
- 1.Sperm form in the testes.
- 2.They pass into ducts and through the vas deferens.
- 3.Seminal-vesicle and prostate secretions are added.
- 4.Semen enters the urethra and leaves through the penis.
Problem
Why can prolonged excessive heat around testes reduce sperm production?
- 1.Sperm formation works best below core body temperature.
- 2.The scrotum normally supports this cooler condition.
- 3.Excess heat can disturb temperature-sensitive development.
- 4.Sperm number or quality may temporarily decline.
Problem
A blockage prevents seminal-vesicle secretion but sperm cells are present. Predict an effect.
- 1.Sperm still contain hereditary material.
- 2.However, the normal supporting fluid is reduced.
- 3.Nutrient supply and transport conditions become less favourable.
- 4.Sperm movement and survival may be impaired, reducing fertility.
The urethra is a shared passage, not evidence that urine and semen mix normally. Body controls coordinate their passage at different times.
Quiz
Where are sperm produced?
Why are testes in the scrotum?
What carries sperm from the testes?
What do seminal vesicles and prostate add?
What helps a sperm move?
Practice Problems
- Label the pathway of sperm using a written sequence.
- Explain the temperature role of the scrotum.
- Describe two functions of testosterone.
- Relate sperm head, middle region and tail to function.
- Predict how blocking the vas deferens differs from blocking the urethra.
Key Takeaways
• Testes produce sperm and testosterone. • The scrotum maintains a cooler environment. • The vas deferens transports sperm. • Seminal vesicles and prostate add supporting secretions. • Semen contains sperm in a nourishing transport fluid. • The urethra serves urinary and reproductive passage at different times. • The sperm head carries hereditary material. • The sperm tail provides motility.