Ch. 17 urinary system check your recall questions

22. List the normal constituents of urine.

95% water, urea, uric acid, may have a trace of amino acids, variety of electrolytes.

5. Trace the blood supply to the nephron.

A renal artery enters a kidney through the hilum and gives off several branches, called interlobar arteries, which in turn give rise to interlobular arteries. The final branches of the interlobular artieroes, called affaremt arterioles, lead to the nephrons.

7. Describe the system of blood vessels associated with a nephron.

Blood enters an efferent arteriole whose diameter is smaller than that of the afferent vessel. The efferent arteriole resists blood flow to some extent, which backs up blood into the glomerulus, increasing pressure in the glomerular capillary. The efferent arteriole branches into a complex, freely interconnecting network of capillaries, called the peritubular capillary system, that surrounds the renal tubule. Blood in the peritubular capillaries system is under low pressure. After flowing through the capillary network, the blood rejoins blood from other branches of the peritubular capillaries system and enters the venous system of the kidney.

17. Define tubular secretion.

Certain substances move from the plasma of blood in the peritubular capillaries into the fluid of the renal tubule.

19. How does sodium reabsorption affect potassium secretion?

During this process, active reabsorption of sodium ions from the tubular fluid result in a negative electrical charge within the tubule. Because positively charged potassium ions and hydrogen ions are attracted to negatively charged regions, these ions move passively for the tubular epithelium and enter the tubular fluid

8. What structures form the juxtaglomerular apparatus?

Enlarged smooth muscle cells juxtaglomerular cells and cells of macula densa.

15. Which mechanisms reabsorb solutes from the glomerular filtrate?

active transport systems through protein carriers that because they are active have a limited transport capacity

11. Which factors influence the rate of glomerular filtration?

Any change in diameters of the afferent and efferent arterioles changes glomerular hydrostatic pressure, also altering the glomerular filtration rate.

10. Which forces affect net filtration pressure?

As another capillaries, the hydrostatic pressure of blood forces substances through the glomerular capillary wall. The osmotic pressure of plasma in the glomerulus and hydrostatic pressure inside the glomerular capsule also influence this movement.

23. What factors affect urine volume?

Fluid intake, environmental temperature and relative humidity of the surrounding air, as well as the person's emotional condition, Respiratory rate, and body temperature.

9. Which processes form urine?

Glomerular filtration, tubular reabsorption and tubular secretion.

14. Which chemicals are normally present in the glomerular filtrate but not in urine?

Glucose is present in glomerular filtrate but absent in urine. In contrast urea and uric acid are much more concentrated in urine then in glomerular filtrate.

4. List the general functions of the kidney.

Help maintain homeostasis by regulating composition, volume, and the pH of the extracellular fluid. They remove metabolic wastes from the blood and dilute them with water and electrolytes to form urine which they excrete; secrete hormones to help control red blood cell production; activation of vitamin D; secrete renin which helps maintain blood volume and blood pressure.

13. How does renin help regulate filtration rate?

Helps maintain blood pressure and blood volume

2. Describe kidney structure

Lateral surface of kidney is convex, but it's medial side is deeply concave. Medial depression leads into a hollow chamber called renal sinus. The entrance to this sinus is the hilum and through it passes blood Vessels, nerves, lymphatic vessels, and the ureter.

3. Name the kidneys functional unit.

Nephron

20. How does the hypothalamus regulate urine concentration and volume?

Neurons in the hypothalamus produce ADH, which the posterior pituitary releases in response to a decreasing water concentration in blood or a decrease in blood volume. When ADH reaches the kidney, it increases the water permeability of the epithelial lining of the distal convoluted tubule and collecting duct, and water moves rapidly out of the segments by osmosis-that is, water is reabsorbed. Urine volume falls, and soluble wastes and other substances become more concentrated, which minimizes loss of body fluids when dehydration is likely.

18. Which substances are actively secreted?

Penicillin creatinine and histamine, hydrogen ions, potassium ions.

6. Name the parts of a nephron.

Renal corpuscle, renal tubule, glomerulus, glomerular capsule, proximal convoluted tubule, descending limb of the nephron loop, ascending limb of the nephron loop, distal convoluted tubule, collecting duct.

12. What is the function of the macula densa?

Sense decreased quantities in chloride, potassium, and sodium ions reaching the distal tubule.

1. Where are the kidneys located?

The kidneys lie on either side of the vertebral column in a depression high on the posterior wall of the abdominal cavity. The upper and lower borders of the kidneys are generally at the levels of the twelfth thoracic and third lumbar vertebrae, respectively. The kidneys are positioned retroperitoneally, which means they are behind the parietal peritoneum and against the deep muscles of the back.

24. Describe the structure of a ureter.

The ureter wall has three layers. The inner layer, or mucus coat, is continuous with the linings of the renal tubule's in the urinary bladder. The middle layer, or muscular code, consist largely of smooth muscle fibers. The outer layer, or fibrous coat, is connective tissue.

21. Explain how urea and uric acid are excreted.

Urea enters the renal tubule by filtration. About 80% of it is reabsorbed, and the remainder is excreted in the urine. For uric acid, active transport reabsorbs all the uric acid normally present in glomeruler filtrate, but a small amount is secreted into the renal tubule and is excreted in urine.

16. Describe the role of passive transport in urine formation.

Water is absorbed passively by osmosis in various segments of the renal tubule.