Excretion - The Kidneys

Question 1

Organs of Excretion

Answer 1

Lungs
Kidneys
Skin

Question 2

Excretory product of lungs

Answer 2

CO2

Question 3

Excretory product of Kidneys

Answer 3

Urea

Question 4

Excretory products of skin

Answer 4

Water, salt, urea

Question 5

What does urine contain

Answer 5

Water
Ions
Urea

Question 6

Excretion

Answer 6

Removal of metabolic waste from the body

Question 7

Examples of Metabolic waste produced by humans

Answer 7

CO2 + water from aerobic respiration

Urea produced by the breakdown of excess proteins in liver

Other substances in excess e.g. medical drugs (e.g. antibiotics) and dietary minerals (e.g. sodium)

Question 8

Dangers of metabolic waste

Answer 8

Toxicity - e.g. CO2 dissolves in water and makes cells acidic -> reduces enzyme activity, lowering rate of metabolic reactions

Osmotic effect - body fluids can become more concentrated due to higher amounts of waste products -> causes water to move out of cells, preventing them from carrying out essential reactions

Uses up necessary storage - needed for useful molecules

Question 9

Main functions of the urinary system

Answer 9

Osmoregulation
Excretion

Question 10

What does the urinary system do?

Answer 10

Removes excess water and urea from the blood.
Creates, stores, and releases urine from the body

Question 11

What is the urinary system made up of?

Answer 11

2 kidneys
2 ureters
urinary bladder
urethra

Question 12

Parts of kidney

Answer 12

Cortex
Nephrons
Medulla
Renal Artery
Renal Vein
Renal Pelvis
Ureter
Bladder
Urethra

Question 13

Parts of kidney: Cortex

Answer 13

The outer layer of the kidney
Has filters called nephrons which filter the blood

Question 14

Parts of kidney: Medulla

Answer 14

The middle layer of the kidney
Has tubes carrying filtered waste to the centre of the kidney

Question 15

Parts of kidney: Renal Pelvis

Answer 15

Area of the kidney where connecting tubes join and connect to the ureter

Question 16

Parts of kidney: Ureter

Answer 16

tube which transports urine to the bladder

Question 17

Parts of kidney: Urethra

Answer 17

Transports urine out of the body

Question 18

Parts of a nephron

Answer 18

Renal Artery
Bowmans capsule
Glomerules
Proximal convoluted tube
Loop of Henle
Distal convoluted tube
Collecting ducts

Question 19

Ultrafiltration

Answer 19

1. Arterioles branching off the renal artery lead to each nephron
2. These flow to the glomerules (bundle of capillaries inside the Bowmans capsule)
3. The capillaries get narrower, increasing the pressure of the blood.
4. This causes small molecules (water, urea, ions, glucose) to be pushed out of the blood into the bowman’s capsule producing a glomerular filtrate
5. Large molecules (e.g. protein and blood cells) remain in the blood due to membranes between blood vessels acting as filters
6. Some of the substances pushed out are useful so are reabsorbed later on in the kidney = selective reabsorption

Question 20

What is reabsorbed during selective reabsorption?

Answer 20

Glucose
Ions/salt
Water

Question 21

What is reabsorbed during selective reabsorption?

Answer 21

Glucose
Ions/salt
Water

Question 22

Where is glucose reabsorbed?

Answer 22

Proximal convoluted tubule

Question 23

By what process is glucose reabsorbed?

Answer 23

Active Transport

Question 24

Adaptations of proximal convoluted tubule for reabsorption of glucose

Answer 24

Many mitochondria to produce energy (for active transport of glucose)

Question 25

Why can reabsorption of glucose only occur in the proximal convoluted tubule

Answer 25

The gate for active transport of glucose are found here

Question 26

People with diabetes and reabsorption of glucose

Answer 26

People without diabetes reabsorb all glucose People with diabetes have high glucose levels so cannot reabsorb all glucose -> it remains in the urine. This is why doctors check during glucose levels to check if someone has diabetes

Question 27

Where are ions/salts reabsorbed

Answer 27

Loop of Henle

Question 28

By what process are ions/salts reabsorbed?

Answer 28

Diffusion

Question 29

Where is water reabsorbed

Answer 29

Loop of Henle and collecting duct

Question 30

By what process is water reabsorbed

Answer 30

Osmosis

Question 31

How is water reabsorbed in collecting duct

Answer 31

In different amounts, depending on how much water the body needs

Question 32

Osmoregulation

Answer 32

the process of maintaining **water** and **salt** concentrations (osmotic balance) across membranes within the body.

Question 33

What is osmoregulation an example of?

Answer 33

Homeostasis

Question 34

What is homeostasis?

Answer 34

Maintenance of a constant internal environment despite changes in the external environment. In order to maintain optimal conditions for enzyme activity/cell functions

Question 35

Importance of osmoregulation

Answer 35

Cytoplasm contains a lot of water Maintaining water levels in the body is important to prevent changes to the body cells due to osmosis

Question 36

What happens if a cell if there is excess water in the blood

Answer 36

Causes cells to swell and burst

Question 37

What happens if a cell has too little water in the blood/ too high of an ion concentration

Answer 37

Causes cells to lose water and destroys cells

Question 38

Where is ADH produced?

Answer 38

Pituitary Gland

Question 39

How does ADH aid osmoregulation?

Answer 39

Controls water reabsorption by the nephrons -> example of negative feedback

Question 40

What happens when blood water levels increase?

Answer 40

1. Detected by hypothalamus 2. Less ADH produced by pituitary gland 3. Collecting duct wall becomes less permeable to water so less water reabsorbed into blood 4. Urine is more diluted

Question 41

What happens when blood water levels decrease?

Answer 41

1. Detected by hypothalamus 2. More ADH produced by pituitary gland 3. Collecting duct wall becomes more permeable to water so more water reabsorbed into blood 4. Urine is concentrated