Lab 4

Question 1

What is the use of the urinary system?

Answer 1

keeps chemicals and water in balance by removing a type of waste (urea) from the blood

urea is produced when foods containing protein like meat, poultry, fish and some vegetables are broken down in the body
it is carried in the bloodstream to the kidneys

Question 2

How many kidneys does a mammal have?

Answer 2

2!

Question 3

What is the main function of the kidney?

Answer 3

• remove liquid waste form blood in the form urine
• keep a stable balance of salts and other substances in the blood
• produce erythropoietin, a hormone that aids the formation of RBCs
• remove urea from the blood

Question 4

How does the kidneys remove urea from the blood?

Answer 4

by filtering units called nephrons

nephrons consists of small blood capillaries called a glomerulus and a tbue called a renal tubule

Question 5

What is urine made of?

Answer 5

urea + water + other waste substance

Question 6

How many ureters do we have?

Answer 6

2
they are narrow tubes that carry urine from kidneys to the bladder
muscles in the ureter walls continually tighten and relax to force urine downward away from kidneys
every 10-15 seconds, small amounts of urne is emptied into the bladder

Question 7

How can you develop a kidney infection?

Answer 7

if the urine backs up from ureters to kidneys or if it is allowed to stand still

Question 8

Describe the bladder.

Answer 8

a triangle shape, hollow organ located in the lower abdomen
held in place by ligaments attached to other organs and pelvic bones
the bladder’s walls relax and expand to store urine and contact and flatten to empty urine through the urethra
it can store up to 2 cups of urine for 2-5 hours

Question 9

What is the purpose of two sphincter muscles?

Answer 9

circular muscles that help keep urine from leaking by closing tightly like a rubber band around the opening of the bladder

Question 10

What do the nerves in the bladder do?

Answer 10

alert a person when it is time to urinate or empty the bladder

Question 11

What is the purpose of the urethra?

Answer 11

tube that allows urine to pass outside the body
brain signals the bladder muscles to tighten squeezing the urine out of the bladder
at the same time, the brain signals the sphincter muscles to relax to let urine exit the bladder through the urethra
if all the signals occur in the right order, the normal urination occurs

Question 12

How is the volume and composition of urine adjusted?

Answer 12

by neural and hormonal mechanisms to maintain constancy of volume and electrolyte concentrations in the body fluids
variations in the intake of type of liquid and their loss by routes other than in urine (breathing, sweat, feces) is balanced by alterations in volume and composition of urine produced

Question 13

What happens when sodium is reabsorbed by renal tubules?

Answer 13

it is accompanied by chloride to maintain electrostatic neutrality
thus amount of sodium excreted can be approximated by estimation of chloride concentration

Question 14

How can we determine the specific gravity or density?

Answer 14

by urinometer

Question 15

What is the specific gravity?

Answer 15

ratio between the weight of a given volume of a solution and the weight of the same volume of water
so higher the specific gravity of urine, the more dissolved solids (urea, sodium, chloride) it contains

Question 16

How can you calculate urine flow rate?

Answer 16

urine flow rate = volume collected for each 60 min time period (ml) divided by 60 min.
for total flow rate = sum of volume in ml of all urine samples except the first divided by 120 min

Question 17

How can you calculate the total chloride concentration?

Answer 17

total chloride content of all urine samples except the first (g) * 1000 / total volume (ml)