Unit 13

What are the two main excretory products of humans?

Carbon dioxide and Urea

Why is the excretion of urea and carbon dioxide needed?

They are toxic

Which organ excretes carbon dioxide?

Lungs

Where is urea formed?

In the liver from excess amino acids

What is the definition of Deamination?

the removal of the nitrogen-containing part of amino acids to form urea

What is the role of the liver in the assimilation of amino acids?

the liver converts excess amino acids to proteins including plasma proteins such as fibrinogen

State 3 things that the kidneys excrete?

Urea, Excess water, Excess salts

What three factors alter the volume of urine produced?

Water intake, Temperature, Exercise

What are the organs and vessels of the human excretory system?

kidney, renal vein, renal artery, ureter, urethra, bladder, aorta, vena cava

What are the three main structural regions of a kidney?

Cortex, Medulla, Ureter

What are the main parts of a kidney tubule (nephron)?

glomerulus (a knot of capillaries), capsule, tubule

What is the role of the glomerulus in the kidney?

Filters water, glucose, urea and salts (small molecules) from the blood

What is the role of the tubule in the kidney?

Reabsorption of all the glucose, most of the water and some salts back into the blood leading to the concentration of urea and loss of excess water and salts in the urine

Describe how blood is filtered in the kidney tubule (ultrafiltration)?

ultrafiltration takes place where high blood pressure due to the narrowing of capillaries forces filtrate to pass through the glomerulus into the capsule. Small molecules like glucose, water, urea and salts move through while proteins and blood cells are too big to move out

What are three functions of kidney dialysis?

1. Removes urea from the blood. 2. Balances salt. 3. Maintains glucose concentration

Describe what happens during dialysis in a kidney machine?

The dialysis membrane is partially permeable allowing salt and urea to diffuse across while water moves by osmosis. Proteins and blood cells are too large to move across, and glucose is not removed because the dialysate has the same concentration as blood

What are the advantages of a kidney transplant compared with dialysis?

patient does not need to return to clinic for dialysis, can eat normally, better quality of life, reduced pain

What are the disadvantages of a kidney transplant compared with dialysis?

need immunosuppressant drugs, risk of rejection of kidney, risk of death during operation