Biology

Male Reproductive System: External and Internal Male Genitals

len Alfred Ajibola - Tue, 06th August, 2019 @ 15:30: PM

Topics in Biology

Male Reproductive System: External and Internal Male Genitals Male accessory sex organs Food Chain, Food Web and Food Pyramid Skeleton, Type of Skeletal Materials and Differences between Cartilages and Bones Bones - Types of Bone Bones and Type of Bone part 2 Red Blood Cells and Hemoglobin Tropical Rainforest and Savanna with their characteristics Desert and Swamp Forest - Types of Desert, Characteristics of Deserts and Swamps Plant Nutrition and Photosynthesis - Autotrophic mode of Nutrition Amazing facts in Biology Protists - Examples and Characteristics of Protists Reptiles - Characteristics of Reptiles Homeostasis and Negative Feedback Mechanism Arteries, Layers of an Artery and Characteristics of Arterial Disorders Introduction to Biology - Basic Characteristics of Life


Academic Questions in Biology

Please check out our Test Your Knowledge page to see all Questions and Answers

Which of the following is a category of long bones?

  • A. Stunted long bones
  • B. Reduced long bones
  • C. Giant long bones
  • D. Bended long bones
  • E. Curved long bones
  • F. Elongated long bones

The end product of photosynthesis is _____.

  • A. O2
  • B. C​​​​​​2​​​​C5OH
  • C. H2​​​​​O
  • D. CO2
  • E. C6H12O6
  • F. C2H5COOH

The above diagram illustrates a _____.

  • A. Food Chain
  • B. Food Web
  • C. Food Pyramid
  • D. Food Link
  • E. Food Hub
  • F. Food zone

The living cells that makes up cartilages are called _____.

  • A. osteocytes
  • B. osteoblasts
  • C. osteoclasts
  • D. chondroblasts
  • E. chrondocytes
  • F. Osteoprogenitor cells

Which of the following statement is incorrect with regards to chitin?

  • A. Ecdysis is a term associated with chitin
  • B. It is a skeletal material
  • C. It is a type of skeleton
  • D. It is present outside the organism
  • E. It does not grow when the organism grows
  • It is present in ants

Which of the following is NOT a function of the human skeleton?

  • A. Gives Shape
  • B. Provides Protection
  • C. Aids in Locomotion
  • D. Supports Movement
  • E. Assists in Inhalation and Exahalation
  • F. None of the above
  • G. All of the above

Organisms that manufacture their own food through the help of sunlight or chemicals are best referred to as _____.

  • A. autotrophs
  • B. chemosynthetic
  • C. photosynthentic
  • D. chemoautotrophs
  • E. photoautotrophs
  • F. chemoautotrophs

Organisms that begins a food chain and also manufacture their food through photosynthesis are best referred to as _____.

  • A. heterotrophs
  • B. autotrophs
  • C. homotrophs
  • D. producers
  • E. photosynthetic
  • F. chemosynthetic

Male Reproductive System:

Reproduction is one of the basic characteristics of life. All living organisms have the ability to give birth to offspring (young of the same kind).

Reproduction can be defined as the process through which organisms give birth to their young (offspring) of the same kind.

Please read on the Basic Characteristics of Life here.

Reproduction can be put into two types. These are:

  1. Sexual Reproduction
  2. Asexual Reproduction

In this article, we will focus our attention on the male reproductive system which is a requirement for sexual reproduction.

The male reproductive system consists of organs (called genitals) that are present both externally and internally.

Reproductive organs present on the outside of the body are generally referred to as external genitalia while those present inside the body are termed internal genitalia.

The Male External Genitalia include the followings:

  • Penis
  • Scrotum
  • Urethra

The Male Internal Genitalia include the followings:

  • Testis
  • Vas Deferens
  • Ejaculatory Duct
  • Seminal Vesicles
  • Prostate Gland
  • Bulbourethral Glands or Cowper’s Gland

Note: The seminal vesicles, prostate gland, bulbourethral glands (Cowper’s glands) are often referred to as accessory organs of reproduction in males.

Please read on the Male Accessory Sex Organs here. (It will give you a better understanding on the explanations below, especially with those relating to Semen).

 

  • Penis

The penis is the copulatory and intromittent organ required for the male sexual act. It is the ideal organ for introducing sperm into the female’s vagina through a process called ejaculation.

Note: For ejaculation to occur, orgasm has to take place.

Orgasm is a series of contraction of the muscles present within the penis which ultimately lead to the release of semen.

This process of ejaculation is the climax of the male sexual act.

Below is a diagram of the Penis and its divisions:

Penis - Len Academy
Image Credit: Teach Me Anatomy

Anatomically or structurally, the penis can be divided into three parts. These are:

1. Root of the Penis: This is the fixed part of the penis and it’s located within a male's body.

Note: The penis actually begins from inside the body, directly below the bulbourethral organs at the pelvic floor.

The root of the penis is made up of two kinds of muscle. These are:

  • Ischiocavernosus Muscle: It helps to produce and maintain erection.
  • Bulbospongiosus Muscle: It assists in the forceful expulsion of semen from the urethra.

2. Body of the Penis: The penile body marks the beginning of the visible part of the penis as it extends from the root to the glans penis.

It is made up of three cylinders of erectile tissues which are two corpora cavernosa and one corpus spongiosum.

Muscles of the Penis - Len Academy
Image Credit: Arizona Center for Advanced Medicine

Note: Erection of the penis is a vascular process; that is, it results from the flow of blood into the corpora cavernosa and corpus spongiosum muscles respectively.

Lack of adequate blood flow to the penis will result to little or no erection. This condition is medically termed Erectile Dysfunction (ED) or Impotence.

The erectile tissues are highly vascular; that is, they can receive a good amount of blood supply. As a result, they play a significant part in the erection of the penis.

Please read on Arteries and Arterial Disorders here.

3. Glans of the Penis: Fondly called the glans penis, it is the expanded and rounded head of the penis.

The Glans penis contains an opening (called urethra) around its center.

At birth, the glans is covered by a fold of foreskin called the prepuce. This foreskin is connected by a soft tissue (called the frenulum) to the neck of the glans.

Often times, the foreskin is removed at birth through a process called circumcision. Parents who do not circumcise their children should clean their glans penis daily so as to prevent bacteria growth around that region.

The glans contains numerous touch receptors and as a result; it can be very sensitive to touch.

Note: Urine and Semen are released from the external urethral orifice; that is; the opening present at the tip of the glans.

 

  • Scrotum

The scrotum or scrotal sacs are visible on every male as it hangs from the body (pelvic region) just between both thighs.

Please read on the Pelvic Bone and Other Bones of the Human Body here.

Inside the scrotal sacs are two oval shaped testicles or testes (singular is testis) which are responsible for the formation and storage of sperm.

The process of sperm formation is referred to as spermatogenesis.

Note: The scrotum is divided in the midline by the perineal raphe.

The perineal raphe is present both in males and females. It is a visible midline on some parts of the human body.

The image below shows the Scrotum, Perineal Raphe and the internal contents of the Scrotum:

Scrotum - Len Academy
Image Credit: Teach Me Anatomy

The scrotum is ideally located outside the body because the formation of sperm requires a temperature slightly lower than that of the body. (About 1o – 7oC lower than the body’s 36.5oC).

Sperm is produced by the testes residing within the scrotum; and the surrounding temperature is extremely important for it's formation. To this end, the scrotal muscles have got a great ability to contract and relax which aids the testes to either move closer to the body or away from it; depending on the surrounding temperature.

As a male, one may have observed that on cold days, the scrotum hangs towards the body. Conversely, it tends to move downwards (away from the body) on warmer days.

Please read on Homeostasis here.

Apart from the testicles, also found in the scrotum are:

1. Epididymis: This is a highly convoluted or coiled tubule of about 6 to 7 meters in length. It serves the following functions:

(A) The epididymis stores sperm for about 80 days, bringing them to maturity.

(B) It also improves sperm motility by absorbing some of the fluids produced by the testicles during sperm formation.

(C) The epididymis also protects the sperm cells.

The epididymis leads into another tubule called the vas deferens. (Please see the diagrams above and below).


2. Spermatic Cord: This is a cord-like structure formed by the vas deferens. It plays an important role in the supply of blood to the testes and vas deferens. It also aids the movement of sperm out of the epididymis into the ejaculatory ducts.

Below is an image showing the contents of the Spermatic Cord:

Testis - Len Academy
Image Credit: Vasectomy Information

Note:The spermatic cord contains a large amount of blood vessels and nerves.

The blood vessels supply blood to the testes, epididymis and cremaster muscles.

Its nerves assist in transferring information back and forth from the scrotum, testicles and the cremaster muscles.


3. Cremaster Muscles: They help in the movement of the testicles towards and away from the body in order to achieve the ideal temperature for sperm formation.

Note Sperm and Semen is not the same thing.

Sperm is the male sex cell (and it happens to be the smallest cell in the human body). It is exactly what meets and fertilizes the female sex cell (ova or egg which is the biggest cell in the human body).

Please read on Amazing Facts in Biology here.

Millions of sperm cells are always introduced into the female’s vagina during ejaculation; and they swim upwards (towards the oviduct or fallopian tube in the female) with the aid of their tail-like structure called flagella.

Semen on the other hand refers to the thick whitish (or slightly yellowish) and viscous fluid released from the penis during orgasm.

The sperm cells are actually present within the semen.

In summary, we can say that the semen contains the following:

  • The sperm cells
  • Amino Acids
  • Enzymes
  • Vitamin C
  • Zinc prostate specific antigen
  • Mucus
  • Prostagladins
  • Phosphatases
  • Silic Acid
  • Flavins

Note: Apart from the sperm cells, many of these components (of the semen) are secretions from the male accessory reproductive glands.


4. Vas Deferens: The vas deferens is found both within and above the scrotum. It is a long muscular tube that begins at the tail of the epididymis and runs through into the ejaculatory ducts. (Please see the diagram above).

Note: The contraction of the smooth muscles of the vas deferens helps in propelling the sperm during ejaculation.

As sperm move from the vas deferens into the urethra, secretions are added to it from the male accessory sex glands.

The vas deferens is also called the ductus deferens.


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len

Alfred Ajibola is a Medical Biochemist, a passionate Academician with over 7 years of experience, a Versatile Writer, a Web Developer, a Cisco Certified Network Associate and a Cisco CyberOps Associate.


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