Notes from NEET topper

sperm

Sperm are the male reproductive cells (gametes) responsible for fertilizing the female egg (ovum) in human reproduction. Here are some key details about sperm:

  1. Production: Sperm are produced in the testes, specifically within the seminiferous tubules. This process is called spermatogenesis and begins at puberty. Spermatogenesis is a continuous process that produces millions of sperm each day throughout a man’s life.

  2. Structure: A mature sperm cell consists of three main parts:

Head: The head contains the nucleus, which carries the genetic material (DNA) of the father. It is covered by a cap-like structure called the acrosome, which contains enzymes to help the sperm penetrate the egg during fertilization.

Midpiece: The midpiece contains mitochondria, which provide the energy (in the form of ATP) needed for the sperm to swim.

Tail (Flagellum): The long tail is responsible for propelling the sperm forward through the female reproductive tract. Its whip-like motion enables the sperm to swim toward the egg.

  1. Function: Sperm are designed for the sole purpose of fertilization. Their primary function is to swim through the female reproductive tract, locate the egg, and penetrate its protective layers for fertilization to occur.

  2. Motility: Sperm are highly specialized for motility. They use their tail to move in a corkscrew-like motion, which allows them to navigate the female reproductive tract efficiently. Only a small fraction of ejaculated sperm reach the vicinity of the egg.

  3. Lifespan: Once released into the female reproductive tract through ejaculation, sperm can remain viable for several days. However, their ability to fertilize an egg decreases over time.

  4. Fertilization: Fertilization occurs when a sperm successfully penetrates the egg. This process typically takes place in the fallopian tube. Once fertilization occurs, the genetic material from the sperm combines with that of the egg, forming a zygote with a complete set of chromosomes.

  5. Chromosomes: Sperm carry 23 chromosomes, including one sex chromosome (X or Y). The sex of the resulting embryo is determined by whether the sperm carries an X (female) or Y (male) chromosome.

  6. Ejaculation: Sperm are released from the male body during ejaculation. They travel through the vas deferens, mix with seminal fluid from the seminal vesicles and prostate gland, and exit through the urethra.

  7. Sperm Count and Quality: Sperm count and quality can vary among individuals. Factors such as age, overall health, lifestyle, and environmental factors can affect sperm production and function. In cases of infertility, a semen analysis can be performed to assess sperm count, motility, and morphology.

  8. Contraception: Understanding sperm and their function is crucial in the development of contraceptive methods. Condoms, for example, act as a barrier to prevent sperm from reaching the egg. Other methods, such as hormonal contraception, aim to inhibit ovulation or alter cervical mucus to prevent sperm from reaching the egg.