Urinary 1 Checklist Gross Anatomy of the Urinary System Urinary system Kidneys Parietal peritoneum Retroperitoneal Renal fascia The urinary system consists of two kidneys, two ureters, the urinary bladder, and the urethra. The kidneys are the major excretory organs of the body, removing waste products from the blood. The kidneys also regulate blood volume, blood ion concentrations, and blood ph. In addition, the kidneys can stimulate erythrocyte (red blood cell) formation, and they assist in the synthesis of vitamin D. The parietal peritoneum is the serous membrane lining the abdominal cavity. Some of the abdominal organs, which are located "behind" the parietal peritoneum, are called retroperitoneal organs. The renal fascia is fibrous connective tissue surrounding the kidneys. In the drawing, the renal fascia is represented as a thin, transparent layer of tissue. The renal fascia helps to hold the kidneys, and structures associated with the kidneys, in place. Mostly, the kidneys are held in place by the organs surrounding them. The renal fascia has anterior and posterior parts. The anterior part of the renal fascia not only covers the kidneys, but extends between them. The veins and artery between the kidneys are highlighted to indicate that they are covered by the anterior part of the renal fascia. The posterior renal fascia is attached to the muscles of the posterior abdominal wall. Perirenal fat Kidney The perirenal fat pads the kidneys, protecting them from mechanical damage. The fat also insulates the kidneys and is an energy storage site. One of two "bean-shaped" organs located on the posterior abdominal wall on each side of the vertebral column. They extend between the12th thoracic and 3rd lumbar vertebrae. Each kidney is approximately 11 cm (4.3 in) long, 6 cm (2.4 in) wide, and 3 cm (1.2 in) thick. In adult males, the average kidney weighs 150 g (5.3 oz), and in adult females averages 135 g (4.8 oz). 1
The kidneys are the major excretory organs of the body, removing waste products from the blood. The kidneys also regulate blood volume, blood ion concentrations, and blood ph. In addition, the kidneys can stimulate erythrocyte (red blood cell) formation, and they assist in the synthesis of vitamin D. The perirenal fat is soft, allowing movement of the kidneys. During respiration, movement of the diaphragm cause the kidneys to move up and down. The normal amount of movement is approximately 3 cm (1.2 in). Adrenal (suprarenal) gland One of two glands (orange) located on the superior end of each kidney. Each gland weighs approximately 5 g (0.18 oz) The adrenal gland produces a variety of hormones, including epinephrine, norepinephrine, cortisol, aldosterone, and androgens. Ureter The ureter is a muscular tube that connects the kidney to the urinary bladder. The ureter is approximately 28 cm (11 in) in length. There are two ureters. Contraction of the ureter's muscular wall moves urine from the kidney to the urinary bladder. Urinary bladder The urinary bladder is a retroperitoneal muscular sac. In adults, the empty bladder is located immediately posterior to the pubic symphysis in the pelvic cavity. In infants and children, the urinary bladder is located superior to the pubic symphysis in the abdominal cavity. At 6 years of age it begins to enter the pelvic cavity, but is not completely within the pelvic cavity until 15-16 years of age. In adults, as the bladder fills it extends superiorly into the abdominal cavity. Typically, it extends about 5 cm (2 in) above the pubic symphysis, but when very distended, can reach the level of the umbilicus (belly button). Micturition (urination) typically occurs when the bladder fills to approximately 280 ml. Filling to 500 ml can be tolerated, but beyond that level it becomes painful. The urinary bladder stores urine produced by the kidneys. Contraction of the urinary bladder's muscular walls pushes urine out of the body. 2
Relationships in the male In males, the urinary bladder is posterior to the pubic symphysis and anterior to the rectum (inferior part of the digestive tract). The inferior opening of the digestive tract is called the anus. Loops of the small and large intestine typically fill the space between the urinary bladder and the rectum Prostate gland The prostate gland is located inferior to the urinary bladder. The prostate gland is an accessory reproductive gland that adds secretions to sperm cells to form semen. Urethra The urethra is a tube connecting the urinary bladder (green pin) to the exterior of the body. In males, it is approximately 18 cm (7 in) to 20 cm (8 in) in length. The urethra is a passageway for urine emptied from the urinary bladder. In males, the urethra is also part of the reproductive system. Parts of the urethra The prostatic urethra passes through the prostate gland. The membranous urethra passes through muscles in the pelvic floor. The spongy urethra passes through the erectile tissue of the penis. The urethra opens to the outside on the distal end of the penis. The opening is called the external meatus of the urethra or the external urethral orifice. Relationships in the female In females, the urinary bladder is posterior to the pubic symphysis and anterior to the vagina. The vagina and uterus are between the urinary bladder and the rectum. The uterus is posterior and superior to the urinary bladder. In females, the urethra is approximately 5 cm (1.6 in) in length. The female urethra opens to the outside anterior to the opening for the vagina. The opening is called the external meatus of the urethra or the external urethral orifice. Note that in females the urethra is not part of the reproductive system. 3
Application Questions 3. Why is the right kidney usually located slightly inferior to the left kidney? 4. Although digestive tract bacteria normally do not cause infections in the digestive tract, if they reach other tissues, they can cause infections. In particular, if they reach the urinary tract, they can spread up the urethra, enter the urinary bladder, and cause urinary bladder infections. Are women or men more prone to develop urinary bladder infections? Explain. 4
Application Answers 3. The left kidney is typically slightly inferior to the right kidney because of the position of the liver. 4. Women are more likely to develop urinary bladder infections than men for two reasons. The anus and the external meatus of the urethra are in close proximity to each other. Improper hygiene can result in the spread of digestive tract bacteria to the urethra. When cleaning after a bowel movement, it is recommended that the wipe be made in an anterior to posterior direction to prevent the spread of digestive tract bacteria into the external genitalia. The urethra is relatively shorter in women than in men, resulting in easier bacterial access to the urinary bladder. In males, the anus and opening to the urethra are separated by a greater distance than in females. In addition, the urethra is much longer, making access to the urinary bladder more difficult. 5