Excretory System

Question 1

why is excretion important ?

Answer 1

allows waste products to be removed, also helps to maintain a constant internal environment

Question 2

what does the excretory system consist of ?

Answer 2

kidneys, bladder, ureters, urethra

Question 3

purpose of the excretory system

Answer 3

filter the blood to remove waste products which would be toxic if they built up

Question 4

excretory system of a mammal

Answer 4

• ureters are 2 tubes which carry urine from kidneys to the bladder
• the bladder stores the urine before it is removed from the body
• the urethra allows the passing of urine from the bladder and out of the body

Question 5

excretory system of a bird

Answer 5

• the ureters are 2 tubes which carry urine from kidneys to the cloaca
• the cloaca allows urine and other waste products to be cleared from the body

Question 6

nitrogenous waste removal

Answer 6

the excretory system removes nitrogenous waste products such as ammonia, salt and water that come from the breakdown of proteins

Question 7

how do mammals remove nitrogenous waste products

Answer 7

remove ammonia in the form of urea that requires water to allow it to be excreted from the body as urine

Question 8

how do birds remove nitrogenous waste products

Answer 8

remove ammonia in the form of uric acid this does not require water and is an insoluble substance

Question 9

describe the kidney and what takes place there.

Answer 9

are the core organ involved in waste removal, contain millions of nephrons where ultrafiltration of the blood takes place producing urine.

Question 10

what is the glomerulus

Answer 10

a knot of capillaries

Question 11

what’s the renal bowman capsule

Answer 11

collects the filtrate from the glomerulus

Question 12

what’s the tubules

Answer 12

allow transportation of filtrate to and from the loop of henle

Question 13

what’s the collecting duct

Answer 13

collects urine and passes to the ureter

Question 14

what’s the countercurrent multiplier mechanism (CCMM)

Answer 14

allows concentrated urine to be produced

longer henle = can produce more concentrated urine

Question 15

what 3 processes are in the kidneys

Answer 15

1. ultrafiltration - removing substances from the blood
2. selective reabsorption - reabsorbing the substances the body needs
3. urine formation - substances which are not reabsorbed travel as urine along the nephron to the collecting duct where waste travels to bladder

Question 16

what’s the body water content controlled by

Answer 16

kindeyse via osmoregulation

Question 17

ultrafiltration

Answer 17

occurs in the renal capsule. blood enters via renal artery and flows through the capillaries under high pressure. small molecules and ions are squeezed out of the blood by pressure into the nephron, larger molecules stay in the blood

Question 18

selective reabsorption

Answer 18

Mostly occurs in the proximal convoluted tubule where simple ions amino acids and glucose diffuse into the blood via channel proteins. some larger molecules may be reabsorbed by endocytosis. loop of henle reabsorbs water and salts

anti-diuretic hormone increases amount of water reabsorbed into the kidneys, released from the pituitary gland to maintain homeostasis

Question 19

CCMM in the loop of henle

Answer 19

1. descending limb - permeable to water, water leaves nephron by osmosis and is reabsorbed, as much as body needs is absorbed
2. ascending limb - permeable to ions because tissue has high conc of water, sodium and chloride ions diffuse out the nephron. conc of salt in A limb decreases further up the limb where at the top some sodium chloride ions are actively pumped out
3. where final reabsorption of ions and water occurs to adjust the water balance. ADH has an effect on the amount of water reabsorbed here

Question 20

what’s osmoregulation

Answer 20

maintaining balance of salt and water concentration in the body to keep a constant osmotic pressure

Question 21

high water content

Answer 21

causes body to be hydrated, detected by the osmoreceptors in the hypothalamus which send a response to the pituitary gland to secrete less ADH. less water is reabsorbed into kidneys resulting in more urine being produced so more water is lost

Question 22

what detects changes in water content

Answer 22

hypothalamus via osmoreceptors and controls regulation of water levels in the body

Question 23

what process is osmoregulation

Answer 23

physiological process

Question 24

low water content

Answer 24

causes the body to become dehydrated, detected by osmoreceptors in the hypothalamus which sends a response to the pituitary gland secrete ADH which increases permeability of the walls of the collecting duct which causes more water to be reabsorbed into kidneys via osmosis resulting in less urine being produced so less water is lost

Question 25

how does osmoregulation keep cells working

Answer 25

if conc to solutions surrounding cells are too high (hypertonic) the cells shrivel

if they become too low (hypotonic) the cell will take too much water in and burst

Question 26

ornithine cycle

Answer 26

takes place in the liver converting ammonia to urea. urea is much less toxic and doesn’t need so much water during excretion

Question 27

uric acid

Answer 27

converts nitrogenous waste to insoluble uric acid which is nearly non toxic. uses more energy to make than urea it requires less water to produce meaning birds require less water in their body and are lighter for flight

Question 28

amino acids and deamination

Answer 28

some animals diets contain a lot of protein that can be used for repair, growth and energy production. however, they are made of amino acids and when being broken down the amino group (NH2) is removed (deamination) and converted to ammonia (highly toxic and needs a lot of water to dilute)

Question 29

liver damage (cirrhosis)

Answer 29

where scar tissue affects normal liver function, cannot be reversed and stops liver function. affects ornithine cycle leaving toxic chemicals to build up

causes - damage to liver from disease, meds or toxins, infection of hepatitis C, excess fat build up in liver

treatments/cure - no cure, preventions are exercise and healthy diet and treatment of underlying conditions

symptoms - loss of appetite, weight loss, vomiting of diarrhoea, lack of energy and increased urination

Question 30

whats nephritis

Answer 30

inflammation of the kidneys which leads to problems with filtering blood effectively

caused by disease, meds, disorders

symptoms - weight loss, protein in urine, increased thirst, increased urination and vomiting