Penis

The Penis

The penis has an internal root and a visible shaft and glansThe exposed, sensitive tip of the clitoris..  The prepuceThe fold of skin covering the clitoris. is the loose skinThe body’s largest organ, providing protection and regulation. on the shaft that allows for expansion during erection. It is very densely innervated with tactile corpuscles(Meissner’s)
Receptors in the dermis that detect light touch and vibration. that sense light touch. The frenulum is an internal connective tissue anchors that secures the prepuce to the glans Circumcision remove the prepuce.

Erectile Tissue

In cross-sectional images of the penis, you can see distinct cylindrical structures. There are two corpora cavernosa and one corpus spongiosum. These structures fill with blood during an erection. The urethraThe tube that carries urine from the bladder to the outside of the body. runs through the corpus spongiosum. It serves as the final passageway for both urineThe liquid waste excreted by the kidneys. and semen. It ends with the external urethral orifice at the tip of the glans.  All have their own wrapping called the tunica albugineaA fibrous layer surrounding the ovary..  The corpora cavernosa are separated by some connective tissue.  At the center of the corpora cavernosa is an artery. The cavernous spaces in the erectile tissue are formed of trabeculae. These trabeculae are like arches of smooth muscle. They create open spaces that blood will fill during an erection.  Each of the corpora cavernosa have a deepAway from the surface of the body. artery, supplying the blood during erection.  On the dorsalRelating to the back side of the body. surface of the penis are also arteriesBlood vessels that carry oxygenated blood away from the heart (except pulmonary arteries, which carr serving the skin and connective tissue of the penis.  And, I guess we should talk about which side of the penis is the dorsal side.  In the anatomical positionA standard reference position where the body stands upright, facing forward, with arms at the sides, the penis is held erect.  Therefore, when erect, these arteries are along the side facing the body.

Erection & Ejaculation

The dorsal artery splits to serve the corpus spongiosum which the deep artery serves the corpora cavernosa.  Parasympathetic fibers release norepinephrineA neurotransmitter involved in attention, arousal, and the fight-or-flight response. which cause these arteries to vasodilate. The trabecular smooth muscle of the erectile tissues relax and blood engorges them.  The bulbourethral glands start to secrete preejaculate and heart rate, respiratory rate, and blood pressureThe force exerted by gases in the respiratory system, affecting airflow and gas exchange. all increase. 

Ejaculation is a sympathetically controlled event.  Initially, peristalsis Rhythmic contractions of smooth muscle that move food through the digestive tract. in the vas deferens occurs. This action allows the prostate and seminal vesicle to add their secretions to the passing spermatozoa.  Upon expulsion, the internal urethral sphincter constricts to prevent urine from entering the urethra.