Biology 🍃 | Excretion | 13

Question 1

From where is carbon dioxide excreted?

Answer 1

Through the lungs.

Question 2

What do the kidneys excrete?

Answer 2

Urea, and excess water & ions.

Question 3

Define excretion.

Answer 3

The process by which waste products from metabolism and other non-useful substances are removed from an organism.

Question 4

Define transport.

Answer 4

Movement of substances from one part of the body to another.

Question 5

Define egestion.

Answer 5

The removal of undigested waste material from the intestine. Only for products not produced by the body and that were never digested, such as fiber.

Question 6

Where are kidneys located?

Answer 6

At the back of the abdomen, on either side.

Question 7

What is a kidney’s function?

Answer 7

• To regulate the water content of blood, something important to maintain blood pressure.
• To excrete toxic waste products of metabolism.

Question 8

What do the ureters do?

Answer 8

They carry urine from the pelvis to the bladder.

Question 9

What does the bladder do?

Answer 9

It stores urine and contracts to empty urine through the urethra.

Question 10

What is the function of the sphincter muscles?

Answer 10

It opens so that urine flows along the urethra out of the body.

Question 11

What is the renal medulla and renal cortex?

Answer 11

The renal cortex is the outer layer of the kidney, and the renal medulla is the inner layer.

Question 12

What is a nephron?

Answer 12

One of the thousands of tiny tubules in a kidney in which urine is produced.

Question 13

Where does a tubule begin and end?

Answer 13

It begins in the cortex, loop down to the medulla, back to the cortex, down again to the medulla, and then to the pelvis.

Question 14

What are the three phases of urine formation?

Answer 14

Filtration, Reabsorption, Formation

Question 15

What is the glomerulus in a kidney?

Answer 15

A specialized bundle of capillaries situated between two resistance vessels of the nephron.

Question 16

What is the function of the glomerulus?

Answer 16

Blood brought through a branch of the renal artery has its molecules, water, and substances squeezed into the renal capsule by the glomerulus.

Question 17

How does filtration occur in urine formation?

Answer 17

Blood is brought to the renal capsule in a branch of the renal artery - molecules, water, and substances, are squeezed out into the renal capsule through the glomerulus walls.

Question 18

How does reabsorption happen in urine formation?

Answer 18

Blood capillaries wrap around each tubule so that the useful substances can be reabsorbed, passing back into the blood. By the time it reaches the collecting duct, it is mostly water, urea, and some salts.

Question 19

Why is reabsorption needed in urine formation?

Answer 19

Some of the fluid in the renal capsule (glucose, some water, some salts) need to be reabsorbed into blood.

Question 20

How does formation happen in urine formation?

Answer 20

Urine from all tubules flows into the ureters, taking it to the bladder.

Question 21

What is the liver’s role?

Answer 21

The assimilation of amino acids. Urea is formed in the liver by excess ammonia.

Question 22

Define deamination.

Answer 22

The removal of the nitrogen-containing part of amino acids for urea formation.

Question 23

Why does the liver split up amino acids?

Answer 23

We cannot store amino acids: yet it would be wasteful to excrete. There is still carbohydrates that can be stored.

Question 24

What are the products of deamination?

Answer 24

Ammonium and carbohydrates (glycogen)

Question 25

Why do we convert ammonia to urea?

Answer 25

Ammonia is toxic.

Question 26

How do amino acids reach the liver?

Answer 26

• They are broken down during digestion into amino acids
• They are absorbed by blood, taken to the liver by the hepatic poral vein

Question 27

What does the liver do to excess amino acids?

Answer 27

Deaminates it to ammonia and carbohydrates.

Question 28

What form are carbohydrates stored in the liver?

Answer 28

Glycogen.