Chapter 26 Reading Questions

Chapter 26 Reading Questions
The Urinary System

Let's experience A Trip to Cairo as a Chapter Overview

I hate flying! First of all you have no control (you are incontinent) over speed or airlift, and secondly you are wedged into this little 60 square foot compartment (1,000,000 nephrons are wedged into the two kidneys) four miles above those nice solid clouds. If you want to travel 5,000 miles to experience Egypt, there is no other choice of transportation. (If you want to rid the body of toxic wastes, urine is involuntarily formed.)

Egypt, of course, is one of the pro-American Middle East countries that is part of the "developing" complexes. (There are 16,000,000 people living in Cairo and no public toilets.) My first impression of the country after leaving the flying cubicle was that of entering a blast furnace. The warm dry air blowing off the Sahara desert felt as though I were standing in front of a giant hair dryer. (The body is going to dehydrate fast, urine output will be way down.) As we drove into Cairo at midnight, the second impression was that these people do not know how to operate a car. No one uses headlights, it might wear down the battery; the hand must always be pressed against the horn because there is no speed limit, and no one uses the brakes. (Fortunately your urinary system does have a brake, it is called the external sphincter muscle.)

Cairo is a wonderful city, with artifacts and a culture totally unique to the western world. Life is very simple, your food for the day costs no more than fifty cents. A bottle of Pepsi is ten cents. No television, no movies, NO AIR CONDITIONERS! The Egyptians are family oriented. Fathers show care and pride in their children as they carry them through the city. Your kidney tubule cells carry all the solutes dissoved in plasma. Five times a day, the Sunni Moslems stopped to chant the Koran offering prayers to Allah. The call to prayer was sung from loud speakers that echoed throughout this cement megatropolis. With improper kidney function, the build up of toxic wastes echoes throughout the body. In the mosques, I was given a robe to cover both head and clothes. Women definitely do not have the freedom or status enjoyed in the western cultures. Most were dressed in long black gallibayas; some wore veils. Out of deference to the culture, no western woman should bare her knees or shoulders in Egypt.

Enough! Why have I chosen this country to represent the urinary system? First of all Cairo is so hot that perspiration does not cool the body. It is amazing the way the kidneys adjust urine output to maintain fluid balance when visiting Cairo. One must produce 450 mls of urine a day to dissolve for elimination the solutes such as urea, creatine, uric acid, and H+. The intake of water must be 2500 mls for that small output. The hormone, ADH, from the hypothalamus controls the concentration of the urine. Second is the pyramids. There are 80 of these throughout Egypt, the largest are at Giza, twenty minutes from Cairo. (Ten cents by bus.) The pyramids are giants rising out of the flat desert. Some of the foundation stones are taller than six feet and together will cover thirteen acres. What incredible monuments to the past! Even today no one knows how they were built. Your kidneys each have 8 to 18 pyramids lying deep within the medulla. These contain the collecting tubules for urine flow and blood vessels. Finally, life in Egypt exists only on the banks of the Nile. The entire population is precariously dependent on the narrow strip of vegetation fed by the Nile River. This river flows from south to north through the middle of Egypt and is the only source of water. (Egypt's annual rainfall is only six inches.) This beautiful river reminds me of the importance of the blood flow through the kidney as well as how we take water for granted. If the Nile does not run, Egypt could not survive. If there is insufficient blood flow through the kidney, you are on hemodialysis.

Part 1: Examination of the Kidneys
    A. Functions of the urinary system
    B. Organs of the urinary system
    C. Gross kidney anatomy
    D. The nephron
    E. Blood flow through the kidney

1. You are about to study two amazing organs, the kidneys. They are shaped
like a swimming pool and regulate the composition and volume of your blood.

Describe the kidney's role in regulating homeostasis.
1. __________________________________________________
2. __________________________________________________
3. __________________________________________________
4. __________________________________________________

List the other systems of the body that play a role in removing wastes.
1._____________________________________
2._____________________________________
3._____________________________________

2. Draw and label below the organs of the female urinary system.

kidneys
ureters
urinary bladder
urethra

3. One part of this system that you must learn inside and out in this course is the anatomy of the kidney. As with any organ, you begin by describing the gross anatomy of the kidney.

A. What is the meaning of the term retroperitoneal?
____________________________________________________
B. Where are the kidneys located in relation to the vertebral column? ____________________________________________________
C. Identify the location and function of the hilus. ____________________________________________________
D. List the three outer layers of tissue surrounding the kidney and their functions.

Layer Function

E. List the internal layers of the kidneys and the structures contained in each.

layer	contents
	1. 2.
	1. 2. 3.
	1. 2.

In the cortex and renal columns the functional unit of the kidney is called the _______________.

4. Draw and label a longitudinal section of the kidney using the ten parts listed in section G above.

5. To summarize the blood flow through the kidney, answer the following questions

A. How much of the cardiac output passes into the kidney each minute?
     ________________________mls.
B. Name the blood vessel that supplies blood to the glomerulus.
     ___________________________________________________
C. The glomerular capillaries reunite and form the
     ___________________________________________________
D. List the system of capillaries that surrounds the proximal
     and distal convoluted tubules to reabsorb the filtrate.
     ___________________________________________________
E. Describe why this system is unique.
    ___________________________________________________
    ___________________________________________________
F. The capillary network that surrounds the juxtamedullary
     nephrons in the medulla is called the _______________________

6. Describe the blood supply through the kidney. At any given time, 20% of the blood is in the kidney. This abundant blood supply enables the nephron to do its work removing wastes and balancing the body's pH and electrolytes. To understand blood flow, draw a flow chart of the renal blood supply in the left hand margin and label the blood vessels of the kidney on the drawing.

renal artery
|
segmental artery
|
______________
|
______________
|
______________
|
______________
|
______________
|
______________
|
______________
|
______________
|
______________
|
______________
|
segmental vein
|
renal vein

7. The microscopic unit of the kidney is called the _________. About 1 X 10⁶ of these filter blood and then pass blood plasma through a system of tubules. As you study the structure of the nephron,
the first part you deals with is the filtering unit, the
Renal Corpuscle.

A. Describe the anatomy of the glomerulus.
____________________________________________________
____________________________________________________
The parietal layer contains ________________________________
The visceral layer contains____________________________
(These starfish-shaped cells regulate the passage of solutes
from blood plasma into Bowman's capsule.)
A. Describe the anatomical features of Bowman's capsule.
____________________________________________________
____________________________________________________
(These contain pores 50-100 nm in diameter that allows for
passage of small solutes out of the glomeruli.

8. Draw and label a renal corpuscle.
Bowman's capsule
glomerulus
afferent arteriole
efferent arteriole
juxtaglomerular cells

9. Explain the function of the renal corpuscle.
___________________________________________________
___________________________________________________
___________________________________________________

10. The second portion of the nephron consists of a series of twisting tubes called the
Renal Tubules.

A. Bowman's capsule drains filtrate into a tightly coiled structure called the ___________________________________________________
B. Identify the location of a cortical nephron.
___________________________________________________
C. Identify the location of a juxtamedullary nephron. ___________________________________________________
___________________________________________________
D. The juxtamedullary nephron has a system of straight tubules that enter
the medulla. List the parts of the tubules in the order in which filtrate flows
into the medulla.

1._______________________________________________
2._______________________________________________
3._______________________________________________

E. Describe the kidney layerwhere the juxtamedullary nephrons become the distal convoluted tubules. ______________________________________________________
F. Contrast the position of the cortical and juxtamedullary nephrons. ______________________________________________________
______________________________________________________
G. Both types of nephrons empty into a common duct called the
______________________________________________________

11. Draw and label a juxtamedullary nephron.

Bowman's capsule
PCT
descending limb
Henles loop
ascending limb
DCT
collecting tubule

Focus Question
It is now time for you to write your own essay question
using the information in this section on kidney structure.
________________________________________________________
________________________________________________________
________________________________________________________