Unit 2: The Excretory System

Question 0

What are the jobs of the excretory system?

Answer 0

1. Nitrogen waster

2. Maintenance of water levels, pH, salts and hormones in the blood

Question 1

What is excretion?

Answer 1

Separating waster products from the body fluids and removing from the body

Question 2

What is the nitrogen waste?

Answer 2

(Ammonia, urea, uric acid) from deaminating the amine group from amino acids must be removed

Question 3

How does the excretory system maintain homeostasis?

Answer 3

Putting any unwanted substances into the urine

Question 4

What are the parts of the excretory system?

Answer 4

Ureter
Bladder
Urethra
Kidneys

Question 5

What is the ureter?

Answer 5

Uses peristalsis to push urine down the bladder

Question 6

What is the bladder?

Answer 6

Stores it one with the help of sphincters that keep urine in until voluntary release

Question 7

Approximately how much urine can an adult bladder hold?

Answer 7

600 mL makes the body lose bladder sphincter control

Question 8

What is incontinence?

Answer 8

The constant loss of bladder control

Question 9

What is the urethra?

Answer 9

Carries urine out of the body (in males, it also carries sperm)

Question 10

What are the kidneys?

Answer 10

Receives blood from the renal arteries, filters it to remove unwanted substances and sends it back out the body through the renal vein (the unwanted substances then for urine) … Contains over 1 million filters called nephrons

Question 11

What hormones does the kidney make?

Answer 11

Epo
Renin
Calcitrol

Question 12

What is the first segment of a nephron?

Answer 12

Bowmans capsule: filtration
- a ball of capillaries (the glomerulus) allows most blood substances (some good and some bad) (water, glucose, ammonia, urea, vitamins) to leave the blood and enter the nephron due to high blood pressure in the capillaries pushing them … This filtrate then moves on through the nephron

Question 13

What cannot be filtrated through the Bowmans capsule?

Answer 13

Protein, red blood cells and platelets stay in the blood as they are too large

Question 14

What are the second and third segment of the nephron?

Answer 14

2. Proximal tubule
3. Loop of Henie
   Reabsorption
   - some of the filtrate is returned back to the blood
   - glucose and vitamins are returned by active transport and then water follows by osmosis

Question 15

What is the fourth segment of the nephron?

Answer 15

Distal tube: secretion

• controlled by hormones
• the blood secretes hydrogen and potassium ions and any antibiotics, electrolytes, and drugs present in order to maintain the pH of the blood

Question 16

What is the fifth segment of the nephron?

Answer 16

Collecting duct: water Reabsorption

• controlled by hormones
• blood reabsorbs most remaining water, leaving very concentrated urine (containing some water, salt, urea, ammonia, creatinine) in the collecting duct, which will then empty into a ureter

Question 17

What steps control water levels?

Answer 17

2, 3 and 5

Question 18

Why steps of the nephron are controlled by hormones?

Answer 18

4 and 5

Question 19

Explain the diagram of the excretory system…

Answer 19

Kidneys at the top … Ureter from kidneys to bladder … Bladder - roundish structure … Urethra from bladder to outside

Question 20

How do the kidneys help control water balance of the body?

Answer 20

Antidiuretic hormone (ADH)

• made by the pituitary gland when blood is hypertonic or when blood volume is too low (called hypovolemia)
• promotes water reabsorption into the blood by making the walls of the collecting duct very permeable to water
• inhibited by alcohol and caffeine
• a 10% loss of water in body tissues = death

Question 21

Describe the negative feedback loop for maintenance of water balance?

Answer 21

Sensor: hypothalamus
- senses blood is hypertonic

Control center: brain

Effector: pituitary gland
- releases ADH to cause water to leave the collecting duct and re enter the blood

Turns off

Question 22

How do the kidneys help control salt balance?

Answer 22

• aldosterone is made the adrenal cortex when blood levels of sodium are too low (called hyponatremia)
• promotes sodium (Na+) Reabsorption into the blood by simulating the active transport pumps in the distal tubule

Question 23

Describe the negative feedback loop for salt balance maintenance…

Answer 23

Sensor: hypothalamus senses blood salt level is too low (detects hyponatremia) and sends a signal to the control center: the brain, through a hormone signal … Renin

Question 24

How does the body maintain blood pressure?

Answer 24

ANH is made by the heart atrium when blood pressure is high or blood volume is too high (called hypervolemia)
Promotes sodium to be added to the ironed and stops the release of aldosterone

Question 25

Describe the negative feedback loop for maintaining blood pressure…

Answer 25

Sensor: kidney - detects high blood pressure or blood volume

Control center: brain

Effector: heart atria - releases ANH which removes sodium from blood and causes water to follow by osmosis …blood pressure lowered

Turns off

Question 26

PH balance of the body…

Answer 26

• sources of excess hydrogen ions are food, liquid and cellular respiration
• when the blood has too much hydrogen (too acidic) the kidneys add it to the urine in the form of NH4 (ammonia)

Question 27

Oxygen concentration maintenance of the body…

Answer 27

• epo is made by the kidney when blood oxygen is too low

- increases the number of red blood cells in the blood

Question 28

Calcium concentration of the body…

Answer 28

• calcitrol is made by the kidneys when blood calcium is too low
• allows calcium to be better absorbed through the digestive tract (stomach)