2. Explain the Four Ways the Kidney Maintains Homeostasis

EXCRETION

Goal:Excretion is the process of getting rid of waste products from cellular metabolism. These unwanted chemical wastesaccumulate in the blood and are removed by body organs, such as the liver, skin, kidney and lungs. The kidney is the main organ of excretion and how it removes wastes and returns water back to the body is vitally important.Read Chapter 16, pgs. 303-317 in “Inquiry into Life”, Mader 11th edition, and using the following questions as a guide make notes on the following topics. You may be required to access the internet or other resources to supplement your textbook.
Urinary System
1. Define excretion and provide an example of products that are excreted.

2. Explain the four ways the kidney maintains homeostasis

Organs of the Urinary System

1. You are expected to be able to identify and provide the function of the following structures:
a. renal veinb. renal arteryc. urinary bladder
d. uretere. urethraf. kidney
2. What is urination and how is it controlled?

Anatomy of the Kidney and Excretion
1. Identify, on a diagram, and describe the function of the following kidney structures:
a. glomerulusb. Bowman’s capsulec. proximal convoluted tubule
d. loop of Henlee. distal convoluted tubulef. collecting duct
g. efferent arterioleh. afferent arteriolei. capillary network
j. renal cortexk. renal medullal. renal pelvis
2. Explain how the following events would change (i) the composition of urine, and (ii)

the urine volume
a. drinking 20 glasses of waterb. dehydration
c. drinking coffee or alcohol (both are diuretics)d. excessive sweating
e. eating salty food
3. Outline the steps involved in urine formation at the nephron. Be sure to include where

each step takes place and how each step affects the composition of the filtrate
Regular Functions of the Kidney

Aldosterone
1. What gland secretes aldosterone?
2. Specifically, how does aldosterone affect the nephron?
3. Explain how aldosterone regulates urine composition?

Antidiuretic Hormone(ADH)
1. Explain how the hypothalamus, posterior pituitary and distal tubule work

together to regulate water and solute levels of the body fluids.

2. How do the following events affect the output of ADH and blood volume?
a. drinking excess waterb. dehydration
3. Explain how ADH operates as a feedback loop for the homeostatic control of

blood concentration.

Atrial Natriuretic Hormone(ANH)
1. Where is ANH produced and explain how it regulates blood volume

Reabsorption of Water

1.Explain how the establishment of a solute concentration in the loop of nephron causes the reabsorption of water in the peritubular capillary network.

2.How do diuretics affect urine and blood volume?

Maintaining Blood pH
1. Explain how the kidney is involved in the maintenance of blood pH.
Problems with Kidney Function
1. Explain how a dialysis machine works and compare its efficiency to the

human kidney.
2. Compare the advantages and disadvantages of haemodialysis and kidney

transplant.