Excretion

Question 1

Define excretion

Answer 1

removal of metabolic waste

Question 2

What is metabolic waste?

Answer 2

products of reactions that have no use in the human body

Question 3

Why is excretion important?

Answer 3

some products of reactions can be toxic

Question 4

Give examples of toxic products of reactions

Answer 4

urea
carbon dioxide

Question 5

How is co2 produced?

Answer 5

respiration

Question 6

How is urea produced?

Answer 6

deamination

Question 7

Where is co2 produced?

Answer 7

respiring cells

Question 8

Where is urea produced?

Answer 8

liver cells

Question 9

Where is co2 removed?

Answer 9

lungs via blood plasma

Question 10

Where is urea removed?

Answer 10

kidneys and skin

Question 11

Describe the structure of the kidney

Answer 11

cortex
medulla
pelvis
1000s of nephrons

Question 12

What is deamination?

Answer 12

break down of amino acids that produces carbohydrates

Question 13

What are the carbohydrates produced in deamination?

Answer 13

glucose - respiration
ammonia - toxic - urea

Question 14

Describe the process of deamination

Answer 14

1. amino acids filtered into liver by hepatic artery
2. amino acids broken down
3. carbohydrates produced (glucose, ammonia)
4. ammonia converted into urea (less toxic)
5. amino acids and urea back into blood stream by hepatic vein

Question 15

Why is ammonia converted into urea?

Answer 15

less toxic

Question 16

Why are the amino acids broken down into carbohydrates in deamination?

Answer 16

body cannot store excess amino acids

Question 17

What is the kidney?

Answer 17

organ that filters blood

Question 18

What processes happen in the nephron?

Answer 18

ultrafiltration
selective reabsorption
water reabsorption

Question 19

What does the nephron contain?

Answer 19

glomerulus
bowman’s capsule
pct
loop of henle
dct
collecting duct

Question 20

What is ultrafiltration?

Answer 20

process that filters blood into the glomerulus at high pressures to form glomerular filtrate

Question 21

What is the glomerular filtrate made of?

Answer 21

water, urea, amino acids and glucose

Question 22

How is a high pressure created in the glomerulus?

Answer 22

afferent arteriole has larger diameter at entrance of glomerulus compared to efferent arteriole at exit

Question 23

What is the Bowman’s capsule?

Answer 23

collection of capillaries

Question 24

What is the glomerulus?

Answer 24

where glomerular filtrate is created

Question 25

What does the high pressure in the glomerulus mean for the glomerular filtrate?

Answer 25

only small molecules can move from the capillaries in the glomerulus into the Bowman's capsule large molecules cannot cross the basement membrane

Question 26

Which large molecules cannot enter the glomerular filtrate?

Answer 26

red blood cells white blood cells proteins

Question 27

What is selective reabsorption?

Answer 27

selective uptake of useful substances like glucose, water and amino acids

Question 28

Where does selective reabsorption happen?

Answer 28

proximal convoluted tubule

Question 29

How is the pct adapted for selective reabsoption?

Answer 29

mitochondria microvilli

Question 30

Why does the pct have lots of mitochondria?

Answer 30

respiration makes ATP for active transport glucose and amino acids move against conc gradient - want to absorb all

Question 31

Why does the pct have lots of microvilli?

Answer 31

increases surface area increases rate of diffusion and active transport

Question 32

Which processes transport glucose, amino acids and salts out of the pct?

Answer 32

active transport diffusion

Question 33

Why does water move out of the pct during selective reabsorption?

Answer 33

glucose and amino acids are removed so water potential is increasing in pct water moves by osmosis down conc gradient water follows glucose and amino acids

Question 34

What happens in the loop of Henle?

Answer 34

concentration of urine

Question 35

What happens in the collecting duct?

Answer 35

water reabsorption

Question 36

Describe how the loop of henle concentrates urine

Answer 36

salts and ions selectively reabsorbed water potential increases water moves by osmosis down conc gradient water follows

Question 37

What is the role of ADH?

Answer 37

makes collecting duct more permeable by making small holes in it

Question 38

How does ADH respond to the body being dehydrated?

Answer 38

more holes reabsorb as much water as possible = osmoregulation

Question 39

What is in urine?

Answer 39

urea water some salts

Question 40

What is in blood plasma?

Answer 40

glucose urea water some salts red blood cells white blood cells protein

Question 41

What is osmoregulation?

Answer 41

collecting duct responding to ADH absorbing as much water as possible because of dehydration

Question 42

ureter

Answer 42

tubes that carry urine from the kidneys to the bladder

Question 43

urethra

Answer 43

tube that carries urine from the bladder out of the body

Question 44

Give two advantages of having a kidney transplant rather than treatment by dialysis

Answer 44

dialysis - regular hospital treatements transplant - continuous, no build-up

Question 45

Give two possible disadvantages of having a kidney transplant.

Answer 45

rejected by other tissues - foreign object infection