Calyx Capsule Column Cortex Hilus Papilla Pelvis Pyramid Renal artery Renal vein Ureter
Fluid collected in Bowman's capsule passes sequentially through the proximal convoluted tubule, the descending limb of Henle's loop, the ascending limb of Henle's loop, and into the distal convoluted tubule. The convoluted tubules and loop of Henle are surrounded by many peritubular capillaries. The distal convoluted tubule curls back to touch the afferent arteriole. Specialized cells of the tubule and of the arteriole at the point of contact make up the juxtaglomerular apparatus.
Urine leaving the nephron empties into a collecting tubule. Several nephrons may empty into one collecting tubule.
Figure 33.3 Nephron
Afferent arteriole Ascending limb of loop of Henle Bowman's capsule Collecting tubule
Descending limb of loop of Henle Distal convoluted tubule Efferent arteriole Glomerulus Juxtaglomerular apparatus Peritubular capillaries Proximal convoluted tubule Renal corpuscle
Urine flows down the collecting ducts in the renal pyramids to the papillae, calyces, and into the renal pelvis. The renal pelvis drains into the ureter which exits at the hilus. The ureters, one from each kidney, empty into the urinary bladder. The urinary bladder empties through the single urethra. Control of urine flow from the bladder is provided by two sphincter muscles at the superior end of the urethra.
The extendable and elastic wall of the bladder is made of four layers. The internal layer is the mucosa, composed of transitional epithelium (see chapter 5) which is able to stretch. Rugae (folds) are also typically present in the relaxed urinary bladder. Deep to the mucosa are the submucosa, muscularis, and the peritoneum. The peritoneum is found only in the superior part of the urinary bladder.
The triangular area formed by the openings of the ureters and urethra in the bladder is the trigone. This area is usually smoother because the mucosa is firmly bound to the muscularis at this point.
Label Figures 33 1, 332, and 33-3-
Identify the following on the models of the kidney and its parts:
Whole kidney: afferent arteriole, calyx, collecting tubule, cortex; efferent arteriole, hilus, loop ofHenle, medulla, nephron, renal artery, renal column, renal corpuscle, renal vein, renal papilla, renal pelvis, and ureter.
Nephron: afferent arteriole, ascending limb ofHenle, collecting tubule, descending limb ofHenle, distal convoluted tubule, efferent arteriole, loop ofHenle, peritubular capillaries, proximal convoluted tubule, and renal corpuscle.
Renal corpuscle: afferent arteriole, Bowman's capsule, distal convoluted tubule, efferent arteriole, glomerulus, juxtaglomerular apparatus, and proximal convoluted tubule.
Examine the sheep kidney. Identify: calyces, cortex, hilus, medulla, renal columns, renal pelvis, renal pyramids, and ureter.
The close association of the reproductive and urinary systems means that these two systems are best studied at the same time in the cat: We will look at the urinary system during our examination of the reproductive system in chapter 36.
Examine a section of the kidney with a microscope. Note the large number of tubules with walls of simple cuboidal epithelium. Be able to identify a glomerulus and Bowman's capsule.
Examine a section through the urinary bladder. Identify the mucosa, muscularis, submucosa, and transitional epithelium.
1. _ What two structures make up the renal corpuscle?
3. _ True/false. The renal columns are extensions of the cortex into the medulla.
4. _ Each renal pyramid empties urine into a (4).
5. _ The juxtaglomerular apparatus is composed of cells of the 131 and the J^l-
7. _ True/false. A collecting tubule can collect urine from more than one nephron.
8. _ The functional unit of the kidney is the (8) .
9. _ The central solid part of the kidney is the (9) .
10. _ True/false. The afferent arteriole is a blood vessel which carries blood to the kidney.
11. _ How many layers are in the wall of the urinary blad der?
12. _ The inner wall of the bladder is (12) epithelial tissue.
13. _ The (13) is a triangular region on the inner wall of the urinary bladder.
15. _ Blood is returned to circulation by the (15) vein.
16. Describe the flow of fluid from the renal corpuscle to the urinary bladder.
17. Why is the mucosa of the bladder composed of transitional epithelial tissue?
18. How is urine elimination controlled?
19. What is the purpose of the muscularis in the urinary bladder?
20. What is the function of rugae in the urinary bladder?
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This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.