chapter 8 - excretion in humans

Question 1

define excretion

Answer 1

excretion is the removal of toxic metabolic wate products from the body

Question 2

what happens if metabolic waste products are not removed?

Answer 2

1. accumulation of CO2. –> reduced blood pH, enzyme reactions affected due to denaturing
2. accumulation of urea and salts –> reduced water potential of blood, high concentrations of urea and salts are toxic to cells

Question 3

what are the organs in the human urinary system?

Answer 3

1. pair of kidneys
2. pair of ureters
3. urinary bladder
4. urethra

Question 4

__________ are the most basic functional units of the kidney

Answer 4

nephrons

Question 5

structure of a nephron (5)

Answer 5

1. Bowman’s capsule
2. proximal convoluted tubule
3. loop of Henle
4. distal convoluted tubule
5. collecting duct

Question 6

blood enters the kidney by the __________ and leaves by the ___________

Answer 6

renal artery, renal vein

Question 7

what does ultrafiltration involve?

Answer 7

1. the afferent arteriole is wider than the efferent arteriole, which creates a high HYDROSTATIC pressure in the glomerulus
2. small molecules in the blood (e.g. water, glucose, amino acids, mineral salts, urea– glomerular filtrate) are forced out of the glomerular blood capillaries into the Bowman’s capsule

Question 8

how is the glomerulus suited for urine formation?

Answer 8

1. glomerulus is a network of blood capillaries, which provide a large surface area for the filtration process
2. the walls of the blood capillaries are one-cell thick. thus, shorter diffusion distance into the Bowman’s capsule
3. blood capillaries have a thin partially permeable membrane. thus, only small molecules in the blood can pass through while large protein molecules, blood cells and platelets cannot pass through as the glomerulus is impermeable to them.

Question 9

what is osmoregulation?

Answer 9

osmoregulation is the control of water potential and solute concentration in the blood to maintain a constant water potential in the body

Question 10

the amount of water is the blood plasma is controlled by _________________. It is produced by a region of the brain called the __________ and is released by the ______________ and increases water reabsorption at the nephrons in the kidney

Answer 10

antidiuretic hormone (ADH), hypothalamus, pituitary gland

Question 11

what are the common causes of kidney failure? (5)

Answer 11

1. high blood pressure
2. diabetes
3. alcohol abuse
4. severe accidents that physically damage the kidney
5. complications from undergoing major surgery