Penis

The penis is the male external genitalia or male copulatory organ. The penis is the external component of the male reproductive system or also known as external genitalia. Some special erectile tissues make up the penis which helps in the erection of the penis. The enlarged end of penis is called the glans penis. At the tip of the glans penis is the slit-like opening called external urethral orifice. It is covered by a loose fold of skin called foreskin or prepuce. The penis contains three cylindrical masses of erectile tissue, two dorsal corpora cavernosa and one ventral corpus spongiosum which helps in the erection of the penis during copulation i.e., coitus. The penis is small but is erected on sexual arousal. There are many sinuses present in the erectile tissue which helps in the blood flow during sexual desire and three bundles of tissue in penis become swollen with blood and hence resulting in erection. The penis becomes rigid when these spaces are filled with blood. The tissues help in the erection of the penis and facilitate insemination. 

Glans penis:    The glans penis is the sensitive bulbous structure at the distal end of the human penis. The glans is anatomically homologous to the clitoral glans of the human female. 

External urethral orifice: at the tip of the glans penis is the slit like opening called external urethral orifice. 

Function: To deliver semen into vagina during sexual intercourse. The penis also allows for the excretion of urine through the urethra to the exterior of the body.