urinary system

Question 1

what does the urinary system do

Answer 1

“The urinary system helps filter out nitrogenous waste and regulates water, electrolyte, and acid-base balance.”The urinary system filters blood through structures called nephrons, and it secretes and reabsorbs electrolytes under the influence of hormones.”

Question 2

what does the kidneys do

Answer 2

The kidneys are key homeostatic organs that maintain the balance and purity of body fluids. Like unseen sanitation workers, they are often taken for granted until they fail. Each day, they filter gallons of blood, removing wastes, toxins, excess ions, and drugs in the form of urine, while returning essential substances to the blood. Although the lungs and skin also help with excretion, the kidneys are the primary organs responsible for eliminating nitrogenous wastes.
“Disposing of wastes and excess ions is only part of the kidneys’ job. As they carry out these excretory functions, the kidneys also regulate blood volume and help maintain the proper balance between water and salts, as well as between acids and bases.”

Question 3

where the kidney is positioned

Answer 3

Although many people think the kidneys are in the lower back, they are actually located higher—against the dorsal body wall in a retroperitoneal position, meaning behind the parietal peritoneum. These small, dark red, bean-shaped organs lie in the superior lumbar region, extending from about vertebrae T12 to L3. Because of the liver’s position, the right kidney sits slightly lower than the left. The lower part of the rib cage offers them some protection.”

Question 4

more abot the kidney

Answer 4

An adult kidney is about 12 cm (5 inches) long, 6 cm (2.5 inches) wide, and 3 cm (1 inch) thick, or about the size of a large bar of soap. It is convex laterally and has a medial indentation called the renal hilum. Several structures, including the ureters, the renal blood vessels, and nerves, enter or exit the kidney at the hilum (Figure 15.2). Sitting atop each kidney is an adrenal gland, which is part of the endocrine system and is a separate organ.

Question 5

how many layers does the kidney have

Answer 5

The kidney has three protective layers. Deep to superficial, they are as follows:

A transparent fibrous capsule encloses each kidney and gives it a glistening appearance.
A fatty mass, the perirenal fat capsule, surrounds each kidney and cushions it against blows.
The renal fascia, the most superficial layer made of dense fibrous connective tissue, anchors the kidney and adrenal gland to surrounding structures.

Question 6

more about kidney

Answer 6

The fat surrounding the kidneys is important in holding them in their normal body position. If the amount of fatty tissue dwindles (as with rapid weight loss), the kidneys may drop to a lower position, a condition called ptosis (to′sis; “a fall”). Ptosis creates problems if the ureters, which drain urine from the kidneys, become kinked. When this happens, urine that can no longer pass through the ureters backs up and exerts pressure on the kidney tissue. This condition, called hydronephrosis (hi″dro-nĕ-fro′sis), can severely damage the kidney.

Question 7

more

Question 8

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Question 9

blood suply

Answer 9

The kidneys continuously cleanse the blood and adjust its composition, so it is not surprising that they have a rich blood supply (see Figure 15.2b and c). Approximately one-quarter of the total blood supply of the body passes through the kidneys each minute. The artery supplying each kidney is the renal artery. As the renal artery approaches the hilum, it divides into segmental arteries, each of which gives off several branches called interlobar arteries, which travel through the renal columns to reach the cortex. At the cortex-medulla junction, interlobar arteries give off the arcuate (ar′ku-at) arteries, which arch over the medullary pyramids. Small cortical radiate arteries then branch off the arcuate arteries to supply the renal cortex. Venous blood draining from the kidney flows through veins that trace the pathway of the arterial supply but in a reverse direction—cortical radiate veins to arcuate veins to interlobar veins to the renal vein, which emerges from the kidney hilum and empties into the inferior vena cava. (There are no segmental veins.)