Excretion

Question 1

What are the excretory products of the organs of excretion?

Answer 1

kidneys: urine (urea, ions, water)
lungs: blood (CO2 and water)
skin: sweat )(water and salt)

Question 2

What are the organs of excretion?

Answer 2

kidney, lungs, skin

Question 3

What is excretion?

Answer 3

The removal of metabolic waste from an organism (metabolic waste is the waste from chemical reactions - what’s not used)

Question 4

What is urea?

Answer 4

A protein which contains nitrogen created in the liver during deamination. (turning excess amino acids into fats/carbs for storage) Excess urea must be excreted. As if too much builds up it can become toxic due to non-functioning of the kidneys.

Question 5

What are the role of the kidneys?

Answer 5

1. remove waste products
2. regulate levels (ion + water)
3. filter blood

Question 6

Where do we get ions and water?

Answer 6

ions from our diet

water from from food/drink

Question 7

What happens in we have too much or too little ions or water?

Answer 7

ions - can cause problems, we lose some ions from sweating but mainly from urine

water - cells lose/gain water through osmosis. if too much water diffuses into cells they will swell/burst. if too little water diffuses into the cells they shrink. we lose water through sweating and urine.

Question 8

How do the kidneys create urine + get nutrients?

Answer 8

1. blood passes through capillaries - surrounded by tubule (proximal + distal) they absorb all small molecules through diffusion - filtration.
2. as they pass through useful molecules are absorbed back into the tubule (selective reabsorption)
3. all excess waste products (urea, ions, water) become urine and go through collecting duct, then down the ureter and stored in the bladder to be urinated through the urethra.

Question 9

What is osmoregulation?

Answer 9

osmoregulation = water regulation

1. hypothalamus (in brain) detects concentration of water in the blood stream.
2. if water levels too low (dehydrated) hypothalamus sends signal to pituitary gland to release more ADH (reabsorb more water) increasing water concentration in the blood stream + create less urine (but higher concentration of urine - more urea + ions and darker).
3. if water levels too high hypothalamus sends signal to pituitary gland to release less ADH (reabsorb less water) decreasing water concentration in the blood stream + create more urine (but lower concentration of urine - lighter).

Question 10

What is ADH?

Answer 10

Anti diuretic hormone

a hormone which signals your tubules/kidneys to reabsorb more water instead of passing it down to excrete as urine.

Question 11

What is negative feedback?

Answer 11

our body is constantly monitoring water levels and adjusting them to keep balanced. therefore if it goes high, then i goes back down maintaining an almost perfectly balanced concentration of water in the blood stream.

• constantly regulating water levels.

Question 12

How is water gained or lost in cells?

Answer 12

osmosis

diffusion of water through a partially permeable membrane from an area of high concentration to low concentration

Question 13

What are the components of urine?

Answer 13

urea, water, ions

Question 14

During selective reabsorption, what useful molecules are absorbed?

Answer 14

all of the glucose, some of the water, some ions but no urea at all, amino acids

Question 15

Describe the passage of blood through the kidneys?

Answer 15

blood is constantly cycles through the kidneys

goes in through the renal arteries and out through the renal veins - which connect to the inferior vena cava (deoxygenated)

in the nephron blood enters into the glomerulus and comes out through the capillaries

Question 16

describe the passage of blood in the nephrons and how urine comes out

Answer 16

blood enters the glomerulus and filters plasma (water content) to the bowman’s capsule

blood passes through the capillaries while the plasma filters through the tubules

all small molecules filter through the capillaries into tubule, then useful ones are sent back to the blood - so we are left with waste products (selective reabsorption)

the waste products are then sent through to the collecting duct where it goes to the ureter (out of the kidney)

Question 17

What are the small molecules that can be absorbed between the tubules and capillaries?

Answer 17

glucose, amino acids, urea, water, ions

unlike proteins/cells as they are too big

Question 18

Name all the organs in the kidney + excretory system

Answer 18

excretory system:
renal artery, renal vein, kidney, ureter, bladder, urethra

kidney: nephron:
glomerulus, bowman’s capsule, proximal convoluted tubule, distal convoluted tubule, collecting duct

Question 19

Where does the waste products/urine go after it all the useful products are absorbed?

Answer 19

The collecting duct - then down to the ureters - stored in the bladder - urinated through urethra when needed (when bladder is full)

Question 20

What happens to the walls of the collecting duct during osmoregulation?

Answer 20

The walls of the collecting duct become more permeable so that water can be reabsorbed easily.