Download Kidney Function - Holy Trinity Academy

DATE:
NAME:
CHAPTER 9
HANDOUT
CLASS:
Kidney Anatomy, Function,
& Regulation.
BLM 9.1.2
Anatomy:
1. Urinary System
Study the diagram above. Name the structures and indicate their functions by completing the following table:
Structure
1.
Function
2.
3.
4.
5.
6.
7.
8.
Copyright © 2007, McGraw-Hill Ryerson Limited, a subsidiary of the McGraw-Hill Companies. All rights reserved.
This page may be reproduced for classroom use by the purchaser of this book without the written permission of the publisher.
1
DATE:
NAME:
CHAPTER 9
HANDOUT
Kidney Anatomy, Function,
& Regulation.
CLASS:
BLM 9.1.2
2. Kidney Structure & Nephron Function:
Study the diagrams above and answer the questions below.
1. The volume of blood entering the kidney through the renal artery in one day is more than the volume
leaving through the renal vein. What does this tell you about where urine comes from?
2. Study the arrangement of the collecting ducts in relation to the renal pelvis. What does this indicate about
the function of the renal pelvis?
Copyright © 2007, McGraw-Hill Ryerson Limited, a subsidiary of the McGraw-Hill Companies. All rights reserved.
This page may be reproduced for classroom use by the purchaser of this book without the written permission of the publisher.
2
DATE:
NAME:
CHAPTER 9
HANDOUT
Kidney Anatomy, Function,
& Regulation.
CLASS:
BLM 9.1.2
How the nephron cleanses the blood
The cleansing of blood in nephrons involves mostly forced filtration. Useful molecules as well as wastes and
excess substances are filtered out of the blood. Then useful molecules are reclaimed and selectively
reabsorbed back into the blood, leaving wastes (urine) to be excreted. A review of blood composition will help
you to understand how it is cleansed.
Study the diagram of a nephron with its surrounding blood vessels that follows. Remember that blood passes
through two capillary beds as it flows around the nephron, and that exchange of components between blood
and surrounding tissues can only occur through thin capillary walls.
1. List all the components of whole blood, beginning with the largest particles. Note that some components
are waste molecules and some are useful. Some useful components occur in excess amounts.
2. Identify where useful molecules and wastes are filtered out of the blood and into the nephron.
3. Where are useful molecules reabsorbed from the nephron back into the blood?
4. Which structure transports the waste molecules (urine) left behind after reabsorption?
5. Which parts of the nephron are in the cortex of the kidney? Which parts penetrate deep into the medulla?
6. A common misconception is that “kidneys filter wastes out of the blood.” Use the words “filtration” and
“reabsorption” to explain why this statement is false.
Copyright © 2007, McGraw-Hill Ryerson Limited, a subsidiary of the McGraw-Hill Companies. All rights reserved.
This page may be reproduced for classroom use by the purchaser of this book without the written permission of the publisher.
3
DATE:
NAME:
CHAPTER 9
HANDOUT
Kidney Anatomy, Function,
& Regulation.
CLASS:
BLM 9.1.2
Urine Formation:
1. Forced Filtration
Urine formation occurs as blood pressure forces filtrate from the glomerulus into the capsule. This bulk flow of
fluids into the capsules of the nephrons in both kidneys creates about 180 L of filtrate per day. All but about 1
L will be actively reabsorbed back into the blood, with great expenditure of ATP.
1. How does bulk flow of filtrate into the capsule differ from diffusion?
2. In what ways is nephric filtration similar to formation of interstitial fluid (lymph) in other tissues in the
body?
3. One of the effects of a drug overdose is a serious decrease in blood pressure. How might this affect
kidney function?
4. Explain why blood cells and proteins are not usually found in the filtrate.
5. Why are useful molecules like glucose and other nutrients found in the filtrate along with urea and other
wastes?
6. Sometimes bacterial infection causes nephritis—an inflammation of membranes in the glomerulus and
capsule. Large pores are created through which blood cells enter the nephron. What symptom would
indicate this problem?
Copyright © 2007, McGraw-Hill Ryerson Limited, a subsidiary of the McGraw-Hill Companies. All rights reserved.
This page may be reproduced for classroom use by the purchaser of this book without the written permission of the publisher.
4
DATE:
NAME:
CHAPTER 9
HANDOUT
CLASS:
BLM 9.1.2
Kidney Anatomy, Function,
& Regulation.
2. Selective Reabsorption
+
–
1. In terms of energy costs to the cells in the proximal tubule, the reabsorption of salt (Na and Cl ) and
water has been called a deal where we get “3 for the price of 1.” Explain.
+
–
2. What other useful substances, in addition to Na , Cl , and water, are reabsorbed in the proximal tubule?
3. Tubular Secretion:
Use the following diagram, which shows a nephron lying within the cortex and the medulla, and your textbook
or other resource to answer the questions below.
1.
2.
3.
4.
5.
Why are the two parts of the nephron loop called “descending” and “ascending”?
Explain the process of reabsorption from the descending loop.
+
Where is the highest concentration of Na found?
Explain the process of reabsorption from the ascending loop.
Explain how reabsorption of ions and water occurs from the distal tubule.
Copyright © 2007, McGraw-Hill Ryerson Limited, a subsidiary of the McGraw-Hill Companies. All rights reserved.
This page may be reproduced for classroom use by the purchaser of this book without the written permission of the publisher.
5
DATE:
NAME:
CHAPTER 9
HANDOUT
Kidney Anatomy, Function,
& Regulation.
CLASS:
BLM 9.1.2
Use this additional information to answer the next question.
Excess ions and other substances are added to the filtrate from the surrounding capillaries in a process
called tubular secretion. This has been called “reabsorption in reverse.”
6. List three examples of substances that are actively secreted into the filtrate. How is blood pH maintained
by tubular secretion?
Composition of Urine:
The following table compares the composition of blood plasma, nephric filtrate, and urine. Study it carefully
and answer the questions that follow.
Comparison of concentrations of substances in Plasma, Filtrate and Urine (mg/100mL)
Substance
Plasma
Filtrate
Urine
Concentration
Change
Inorganic ions (all) 0.9
0.9
<0.9 – 3.6
<1 – 4×
+
K
0.02
0.02
0.15
7.5×
Amino acids
0.05
0.05
none
–
Proteins
8.0
none
none
–
Glucose
0.01
0.01
none
–
Urea
0.03
0.03
1.8
60×
Note: The pH of blood plasma and filtrate is 7.4. The pH of urine is 4.8–7.5.
1. Study the concentrations of the ions, the amino acids, glucose and urea. Why are their concentrations in
the filtrate identical to those in the plasma?
2. Neither glucose nor proteins are present in urine, but for different reasons. Explain.
3. Although urea (a waste molecule) undergoes less reabsorption than glucose, its concentration in the urine
has increased about 60-fold. Account for the increase.
+
4. Give two reasons to explain why K is more concentrated in the urine than in the filtrate.
5. Which ion accounts for the low pH of the urine? How and where is this ion transported into the urine? Why
is the elimination of this ion important to survival?
Copyright © 2007, McGraw-Hill Ryerson Limited, a subsidiary of the McGraw-Hill Companies. All rights reserved.
This page may be reproduced for classroom use by the purchaser of this book without the written permission of the publisher.
6
DATE:
NAME:
CHAPTER 9
CLASS:
Kidney Anatomy, Function,
& Regulation.
HANDOUT
BLM 9.1.2
Hormonal Control:
1. Regulation of Osmotic Pressure
After eating a salty meal or neglecting to drink water regularly, the osmotic pressure (“saltiness”) of body fluids
increases. This is the stimulus that initiates a series of events in which urine becomes scant and concentrated
because more water is reabsorbed from the urine as it passes through the salty medullary tissues. A hormone
called ADH increases the permeability of the distal tubules and collecting ducts, allowing osmosis to occur.
This response tends to return osmotic pressure of body fluids to normal, especially when an accompanying
thirst causes increased water intake.
How ADH lowers osmotic pressure
STIMULUS
 in osmotic
pressure of
body fluids

SENSOR
osmoreceptors
in the
hypothalamus
stimulate

CONTROL
CENTRE
pituitary
gland
ADH

EFFECTOR
distal tubules
and collecting
ducts in
nephrons

RESPONSE
 water
reabsorption into
the blood because
tubule walls are
permeable to
water (urine is
concentrated and
scant)
NEGATIVE
FEEDBACK
 in osmotic
pressure of
body fluids
1. Redraw the chart to show the response to drinking several glasses of water, which decreases the osmotic
pressure of body fluids. Choose an appropriate title for your chart.
2. How do diuretics such as alcohol and caffeine affect this homeostatic mechanism?
2. Regulation of Body Fluids
When someone suffers a serious extensive blood loss, body fluid volume decreases. The decrease in fluid
volume tends to decrease blood pressure, but the homeostatic mechanism presented below helps to maintain
blood pressure until blood loss becomes critical and death is imminent.
How aldosterone raises blood pressure
STIMULUS
 in blood
pressure

SENSOR
kidneys
secrete
a signal

CONTROL
CENTRE
adrenal
cortex
gland

EFFECTOR
nephrons

RESPONSE
+
 Na and H2O
reabsorption
increases body
fluid
volume
I
aldosterone
NEGATIVE
FEEDBACK
 in blood
pressure
1. Aldosterone stimulates the reabsorption of sodium ions in the nephrons. How does this lead to an
increase in water reabsorption?
2. Drinking salty water tends to increase body fluid volume. What effect might this increased volume have on
secretion of aldosterone? How might the nephrons respond?
Copyright © 2007, McGraw-Hill Ryerson Limited, a subsidiary of the McGraw-Hill Companies. All rights reserved.
This page may be reproduced for classroom use by the purchaser of this book without the written permission of the publisher.
7
DATE:
NAME:
CHAPTER 9
HANDOUT
Kidney Anatomy, Function,
& Regulation.
CLASS:
BLM 9.1.2
Technology:
Kidney Dialysis
When kidney failure occurs, blood plasma is said to become uremic, because urea molecules accumulate to
dangerous levels. Imbalances in other substances also occur.
Dialysis is a medical procedure in which the composition of the plasma can be corrected through simple
diffusion. Dialysing fluid (dialysate) is separated from the patient’s blood (uremic plasma) by thin
semipermeable membranes. Molecules and ions diffuse into or out of the patient’s plasma, depending upon
the composition of the dialysate. Thus, careful formulation of dialysate is the key to correcting the composition
of uremic plasma.
In hemodialysis, diffusion occurs across artificial membranes. In peritoneal dialysis, it occurs across the
intestinal lining (peritoneum). These procedures are illustrated below.
Copyright © 2007, McGraw-Hill Ryerson Limited, a subsidiary of the McGraw-Hill Companies. All rights reserved.
This page may be reproduced for classroom use by the purchaser of this book without the written permission of the publisher.
8
DATE:
NAME:
CHAPTER 9
HANDOUT
Kidney Anatomy, Function,
& Regulation.
CLASS:
BLM 9.1.2
Use the table below, which shows the composition of the dialysate compared to normal plasma and uremic
plasma, to answer the questions that follow.
Composition of Plasma and Dialysing Fluid (various units)
Component
Normal Plasma
Uremic Plasma
+
Potassium (K )
5
8
‾
Bicarbonate (HCO3 )
27
14
Glucose
100
100
Urea
26
200
Dialysate
5
27
125
0
1. Explain why the dialysate is produced with a concentration of 5 units of potassium ions.
2. What is the function of bicarbonate ions in the blood? Suggest an explanation for the decreased
concentration of bicarbonate ions in uremic plasma.
3. What evidence is given in the table that kidney failure has little effect upon glucose metabolism? Given
the glucose concentration of normal plasma, why might dialysate be made to contain 125 units of
glucose?
4. What is the concentration of urea in normal plasma? Suggest an explanation for the lack of urea in the
dialysate.
Copyright © 2007, McGraw-Hill Ryerson Limited, a subsidiary of the McGraw-Hill Companies. All rights reserved.
This page may be reproduced for classroom use by the purchaser of this book without the written permission of the publisher.
9