Question

describe how the muscles of the anus and urethra are similar. What is the benefit of the organisms arrangement?

Answer 1

A*us is an opening that is connected to lower gastrointestinal tract.It is composed of cells called squamous cells.It has two muscles, internal sphincter and external sphincter.Internal anal sphincter is a muscle ring that is surrounding the anal canal.It is an involuntary muscle and is about 5mm thick.It is always in a state of contraction and this contractions are stimulated by sypathetic fibers.These contractions are inhibited by parasympathetic fibers. The external sphincter is an elliptical shaped muscle attatched to skin surrounding the margin of an*s.It is a voluntary muscle and is about 8 to 10cms in length and consists of two stratas called superficial and deep.Superficial strata is the main portion of this muscle and it is formed from a narrow band called anococcygeal raphe.The deep strata is formed by fibers surrounding anal canal.

Urethra is a tube which is connecting urinary bladder to the urinary meatus.The urethral muscles are also two muscles called external and internal sphincters that helps to control the exit of urin in males and females.The internal sphincter of urethra is located at the inferior end of the bladder and proximal end of urethra.It is a smooth muscle which continues from the detrusor muscle.It is also an involuntary muscle.The external sphicter is located at the distal inferior end of bladder in females and inferior end of prostate in males.This is a voluntary muscle that controls the flow of urine which in turn is controlled by somatic nervous system.

These muscle arrangements in a*us interior sphincter is in a state of maximum contractions that helps in the expulsion of feces.This muscle is important for bowel movements.When rectum is filled ,the rectal walls are swollen by the rectoanal inhibitory reflex and the muscle relaxes, triggering defecation.The external sphincter is in a tonal contraction state that helps to keep anal canal shut.It voluntarily relaxes during defecation.In urethral muscles also the control of urine is provided by the arrangement of these muscles.Its involuntary and voluntary actions provides control of urination in both male and female.