Chapter 25, Urinary System
1. Know functions of urinary system.
The Primary Functions of the Urinary System include:
1. Excretion – removal of organic wastes from body fluids 2. Elimination – discharge of waste products
3. Homeostatic regulation – of blood plasma volume and solute concentration
• Kidneys are major excretory organs
o Like a city’s water treatment plant!
• Urinary bladder is the temporary storage reservoir for urine • Ureters transport urine from the kidneys to the bladder • Urethra transports urine out of the body
• How does the urinary system control pH?
o Regulation of plasma hydrogen ion concentration (pH). The kidneys partner up with the lungs and they together control the pH. The kidneys have a major role because they control the amount of bicarbonate excreted or held onto. The kidneys help maintain the blood Ph mainly by excreting hydrogen ions and reabsorbing bicarbonate ions as needed.
• Blood pressure?
o The urinary system plays a role in maintaining normal blood pressure by secreting the enzyme renin. One of the important functions of the kidneys is to regulate blood pressure. Healthy kidneys make hormones such as renin and angiotensin. These hormones regulate how much sodium (salt) and fluid the body keeps, and how well the blood vessels can expand and contract. This, in turn, helps control blood pressure. They do this by regulating:
• The amount of water in the body. If there is too much water in the body (fluid overload) blood pressure will go up. If there is too little water in the body (dehydration) the blood pressure will drop. • The width of the arteries. The arteries constantly change in width as blood flows through them. The narrower the arteries, the higher the blood pressure. Renin helps control narrowing of the arteries. Failing kidneys often make too much renin. This raises blood pressure. If your blood pressure is high, your heart is working harder than normal to pump blood through your body. High blood pressure (also called hypertension) caused by a breakdown in these functions is common in people with kidney failure. It is also a complication, a secondary condition caused by kidney failure. • RBC production?
o The urinary system controls red blood cell production by secreting the hormone erythropoietin.
2. What structures enter or exit at the hilum of the kidney? • Ureters, renal blood vessels, lymphatics, and nerves enter and exit at the hilum
3.Know the anatomy of the kidney so that you could recognize the following parts from a description or on a diagram: capsule, hilum, renal artery, renal vein, ureter, cortex, medulla, papillae, renal columns, minor and major calyces, renal pelvis. • EXTERNAL KIDNEY ANATOMY
A. The Kidney is bean-shaped and located in the lumbar region of the body. The kidney
is described as being Retroperitoneal-that is, it is located between the dorsal body wall
and the parietal peritoneum.
1. An average human kidney weighs about 5 ounces.
2. Sitting on top of each kidney is a single adrenal gland that essentially has no
influence on the kidney.
B. The Renal Hilum-vertical cleft on the medial surface of the kidney, that leads into an
internal space within the kidney known as the Renal Sinus.
1. The ureter, the renal blood vessels, lymphatics and nerves all join each other at
the hilum and occupy the renal sinus.
C. There are Three Layers of Support Tissue Surrounding each kidney. The layers are:
1. The Fibrous Capsule-a capsule-like layer that prevents infections in
surrounding regions from spreading to the kidney.
2. The Perirenal Fat Capsule-a thick layer of adipose tissue that attaches the
kidney to the posterior body wall and...