Removal of Urine

Urine is drained from the renal pelvis and carried by the ureter to the urinary bladder (Fig. 13-4). Urine is stored in the bladder until fullness stimulates a reflex contraction of the bladder muscle and expulsion of urine through the urethra. The female urethra is short (4 cm; 1.5 in) and carries only urine. The male urethra is longer (20 cm; 8 in) and carries both urine and semen.

The voiding (release) of urine, technically called micturition or urination, is regulated by two sphincters (circular muscles) that surround the urethra. The upper sphincter, just below the bladder, functions involuntarily; the lower sphincter is under conscious control.

Interior The Urinary Bladder

FIGURE 13-4. Interior of the urinary bladder, shown in a male subject. The trigone is a triangle in the floor of the bladder marked by the openings of the ureters and the urethra. (Reprinted with permission from Cohen BJ, Wood DL. Memmler's The Human Body in Health and Disease. 9th Ed. Philadelphia: Lippincott Williams & Wilkins, 2000.)

Y hern i


Antidiuretic A hormone released from the pituitary gland that causes reab-

hormone (ADH) sorption of water in the kidneys, thus concentrating the urine an-ti-di -u-RET-ik


A substance that increases blood pressure; activated in the blood


by renin, an enzyme produced by the kidneys


A cuplike cavity in the pelvis of the kidney; also calix (plural,


calyces) (root cali, calic)

erythropoietin (EPO)

A hormone produced by the kidneys that stimulates red blood


cell production in the bone marrow

glomerular capsule

The cup-shaped structure at the beginning of the nephron that

glo-MER-u-lar KAP-sul

surrounds the glomerulus and receives material filtered out of

the blood

glomerular filtrate

The fluid and dissolved materials that filter out of the blood and

glo-MER-u-lar FIL-trat

enter the nephron at the Bowman capsule


The cluster of capillaries within the glomerular capsule (plural,


glomeruli) (root glomerul/o)


An organ of excretion (root ren/o, nephr/o); the two kidneys filter


the blood and form urine, which contains the waste products of

metabolism and other substances as needed to regulate the water

and electrolyte balance and the pH of body fluids


The voiding of urine; urination



A microscopic functional unit of the kidney; working with blood


vessels, the nephron filters the blood and balances the composi-

tion of urine

reonal cortex

The outer portion of the kidney

RE-nal KOR-tex

renal medulla

The inner portion of the kidney; contains portions of the


nephrons and tubules that transport urine toward the renal


renal pelvis

The expanded upper end of the ureter that receives urine from


the kidney (root pyel/o, from the Greek word for pelvis, mean

ing "basin")

renal pyramid

A triangular structure in the medulla of the kidney composed of


the loops and collecting tubules of the nephrons


An enzyme produced by the kidneys that activates angiotensin in


the blood

Normal Structure and Function, continued

tubular reabsorption

The return of substances from the glomerular filtrate to the blood

TUB-u-lar re-ab-SORP-shun

through the peritubular capillaries


The main nitrogenous (nitrogen-containing) waste product in the




The tube that carries urine from the kidney to the bladder (root




The tube that carries urine from the bladder to the outside of the


body (root urethr/o)

urinary bladder

The organ that stores and eliminates urine excreted by the

U-ri-nar-e: BLAD-der

kidneys (root cyst/o, vesic/o)


The voiding of urine; micturition



The fluid excreted by the kidneys. It consists of water, elec-


trolytes, urea, other metabolic wastes, and pigment. A variety

of other substances may appear in urine in cases of disease

(root ur/o).

Box 13-1 Words That Serve Double Duty

Some words appear in more than one body system to represent different structures. The medulla of the kidney is the inner portion of the organ. Other organs, such as the adrenal gland, ovary, and lymph nodes, may also be divided into a central medulla and outer cortex. But medulla means "marrow," and this term is also applied to the bone marrow, to the spinal cord, and to the part of the brain that connects with the spinal cord, the medulla oblongata.

A ventricle is a chamber. There are ventricles in the brain and in the heart. The word fundus means the back part or base of an organ. The uterus has a fundus, the upper rounded portion farthest from the cervix, and so does the stomach. The fundus of the eye, examined for signs of diabetes and glaucoma, is the innermost layer where the retina is located. A macula is a spot. There is a macula in the eye, which is the point of sharpest vision. There is also a macula in the ear, which contains receptors for equilibrium.

In interpreting medical terminology, it is often important to know the context in which a word is used.

Was this article helpful?

0 0
Mole Removal

Mole Removal

Moles, warts, and other unsightly irregularities of the skin can be bothersome and even embarrassing. They can be removed naturally... Removing Warts and Moles Naturally! If you have moles, warts, and other skin irregularities that you cannot cover up affecting the way you look, you can have them removed. Doctors can be extremely expensive. Learn the natural ways you can remove these irregularities in the comfort of your own home.

Get My Free Ebook


  • sabrina
    What is the function of the urethra?
    8 years ago
  • wesley
    What is the two structures that surround the urinary bladder?
    8 years ago
  • neftalem
    What is the base of the bladder?
    4 years ago
  • landolfo
    What is the medical term for the ‘inner portion of the kidney’?
    3 years ago
    What is the medical process of removing products from urine?
    1 year ago

Post a comment