b3

Question 1

the function of the urinary system

Answer 1

urinary system consists of kidney ureter bladder and urethra. the urinaty bladder is a hollow muscular organ which collects urine from the kidneys before disposal by urination. the urine enters the bladder via ureter and leaves bladder via urethra. 2 types of blood vessels attached to kidneys. the renal arteries an deliver oxygen rich bloody supply to the cells in each kidney. once blood has been processed it leaves kidneys via renal vein and transports in the inferior VC back to heart. the kidneys are the main organs in the excretory system = 2 main functions> excretion=removal of potentionally toxic waste products made in cells during metabolism and osmoregulation=homeostatic control of body water by adjusting the solute conc in the cells + body fluid. this ensures the cells dont shrink or burst which would affect cell reactions/metabolism. mammals usually have 2 kidneys at the back of the abdominal cavity at either side of the spine.

Question 2

whats excretion

Answer 2

the removal from the body of potentionally toxic waste products made in the cells during metabolism

Question 3

whats osmoregulation

Answer 3

the homeostatic control of body water by adjusting the solute conc of the cells and body fluids. this ensures cells dont burst or shrink which would affect cell reactions/metabolism

Question 4

what does the urinary system consist of

Answer 4

kidney
ureter
bladder
urethra

Question 5

describe how water is reabsorbed from the collecting duct

Answer 5

it is reabsorbed down a concentration gradient by diffusion through aquaporins under the influence of ADH

Question 6

give one reason why there is no protein in the urine

Answer 6

molecules are too large to pass through

Question 7

which process do white blood cells in the lungs use to ingest bacteria

Answer 7

endocytosis

Question 8

phagocytic cells contain many mitchondria explain why

Answer 8

they contain mitochondria because they are needed for ATP production which allows an increase in aerobic respiration therefore allowing more diffusion and more energy which is needed to make enzymes for digesting

Question 9

explain how the destruction of alveoli walls affects gaseous exchange

Answer 9

they reduce the surface area which means there is less diffusion

Question 10

describe how peak expiratory flow rate can be used to assess respiratory conditions such as COPD in a person

Answer 10

• measures how fast yiu can blow air out of lungs
• takes best of 3 readings
• to find max speed of expiration
• can help diagnose asthma
• can indicate emphysema
• can monitor if condition is improving/getting worse
• can inform when to use inhaler
• can keep a diary and be reviewed with GP/nurse

Question 11

describe the kidneys

Answer 11

• recieves blood supple from branch called aorta in renal artery
• blood comes in under high pressure to make filtration effcient - fiktered blood leaves kidneys along renal vein
• filtered waste product excreted by kidney as urine - urine passes down muscular tube(ureter) ureter connecting each kidney to bladder - bladder is muscular sac which stores urine

Question 12

describe the structure of the kidney

Answer 12

two distinct regions an outer cortex and an inner medulla
blood is brought to kidneys by renal artery and taken away by renal vein
inside kidney arteries divide into smaller blood vessels called arterioles
inside kidneys lie functioning unit called nephrons

Question 13

describe the nephron

Answer 13

• nephron begins with a group of convulated blood capillaries called glomerulus
• G is surrounded by a cup shaped structed called bowmans capsule
• BC leads to longest part of the nephron the PCT
• PCT then lesds into the hairpin shaped structure called the LOH
• LOH leads into the DCT
DCT leads finally into the collecting duct

Question 14

what two processes do kidneys produce urine in

Answer 14

• first small molecules and ions are filtered out of the blood in the G and into the BC = ultrafiltration
• any of the ions and molecules required by body are taken back from the nephron and moved back into the blood a process called selective reabsorption e.g., glucose

Question 15

describe the formation of the glomerular filtrate

Answer 15

this is done by ultrafiltration so is sinilar process used to force tissue fluid out of capillaries
• blood enters kidney through RA which branches into around 1 mill tiny arterioles each of which enters BC
• the afferent arteriole that enters the capsule is wider in diamter than efferent that exits. = causes high hydrostatic pressure in capillaries within capsule - capillaries known as glomerulus
• the higher than normal hydrostatic pressure in the G leads to water, glucose, urea and mineral ions being forced out of the fenestrations in the capillaries to form the glomerular filtrate
• blood cells and large plasma proteins cannot pass through the small holes and so remain in the capillaries
• ultrafiltration not specific only fikters by size a lot of useful molecules are also filtered out that we do not want to waste e.g., glucose

Question 16

describe the proximal convukated tubule and selective reabsorption

Answer 16

fluid which enters BC is known as glomerular filtrate.
filtrate then passes into proximal convulated tubule. studies have shown that all the glucose amino acids and most of the water and salt are reabsorbed in the proximal convulated tubule
glucose is an important energy source that the body cannot afford to lose

Question 17

describe the loop of henle

Answer 17

• LOH make it more possible to excrete urine that is more concebtrated than the blood
• role = to create a very high conc of salts in the tissue fluids of the medulla through which the collecting ducts passes
• has two regions > an ascending limb and descending limb both run parallel to eachother and surrounded by blood capillaries. top part is thicker than bottom part
• descending limb is permeable to water but not Na+ and Cl- ions
• ascending limb is permeable to Na+ and Cl- ions but not to water

Question 18

explain how th LOH created a high conc of solutes in tissue fluids

Answer 18

• top part of AL sodium and chloride ions are actively pumped out into surrounding tissue fluids of medulla
• created a high solute conc in TF > very salty
• DL and AL are running parallel and very close to eachother
• as filtrate moves down DL water is drawn out of filtrate by osmosis
• as fiktrate descends LOH it becomes more + more concentrated because all water is leaving the filtrate
• water is removed quickly by capillaries
• Na and Cl leave filtrate by diffusion therefore further increasing the conc of salt ions in the tissue fluid of the medulla

Question 19

Describe what happens to the concentration of the filtrate as it passed down the descending limb
of the loop of Henle

Answer 19

it increases

Question 20

Describe what happens to the concentration of the filtrate as it passes up the ascending limb of the loop of Henle

Answer 20

it decreases

Question 21

summarise the LOH

Answer 21

in summary the loop of Henle has not significantly made the filtrate any more concentrated but it has created an area of high solute concentration in the medulla region of the kidney.
The longer the loop of Henle, the greater the solute concentration set up in the medulla so the more water is reabsorbed and the more concentrated the urine becomes. Mammals that inhabit arid areas such as deserts, have particularly long loops of Henle, since they need to conserve as much water as possible.
The thicker the medulla the longer the loop of Henle that passes through it. So, the thicker the medulla, the more concentrated the urine is.

Question 22

The kangaroo rat is well adapted to desert conditions and is able to survive on little or no water intake. How?

Answer 22

• Most of its water gain comes from its food. The food may be completely dry but ‘metabolic water’ is produced from it during respiration in the cells. So, all the water needs of the kangaroo rat are satisfied directly or indirectly from its food.
• Kangaroo rats remain underground during the day. The air in their burrows is cooler and more humid, so less water is lost from the body by evaporation.
•The kangaroo rat is able to conserve body water by producing a highly concentrated urine. It is also able to produce very dry faeces.
•Its nasal passages are adapted to cool the air before it is breathed out. So respiratory moisture condenses in the nasal passages before it can be exhaled.

Question 23

describe the role of the collecting duct and ADH

Answer 23

CD runs parallel to LOH. CD has an important role in osmoregulation. If the water content of blood is too low the pituatary gland releases the hormone ADH. this hormone makes the cells of the CD develop membrane channels called aquaporins making CD permeable to water. As filtrate passes down CD due to ^ conc of solutes in medulla most of water is reabsorbed back into blood by osmosis.

Question 24

if the water content of the blood suddenly becomes too high what will happen

Answer 24

water will enter the cells by osmosis and cause them to burst leading to tissue damage

Question 25

explain how urea is concentrated in filtrate

Answer 25

it is concentrated in filtrate due to the reabsorption if water by osmosis.

Question 26

Explain how ADH causes movement of water from the lumen to the collecting duct

Answer 26

ADH causes vesicles containing aquaporins to be inserted into membrane
the water then enters the cell through aquaporins by osmosis down a water potential gradient from the cell to the capillary via tissue fluid

Question 27

describe the role of the renin-angiotensin-aldesterone mechanism in BP regulation

Answer 27

• BP drops = some cells in K produce renin
• renin converts angiotensin to angiotensin I
• angiotensin I is converted to angiotensin II by the enzyme angiotensin converting enzyme (ACE)
• hormone aldosterone is then released
• more sodium ions are reabsorbed into the blood
• water enters the blood
• BP increases

Question 28

explain what can be done if kidney faikure was to occur

Answer 28

variety of causes e.g., cancer, physical trauma, disease etc.
1. kidney dialysis = during this a pateints blood is pumped into a device that contains a large SA of a membrane. on one side is patients blood and other side is a solution that is similar to patients blood but does not have urea in it in start of dialysis. urea is small enough to diffuse through so slowly some of urea leaves the blood and enters the solution. balance of water and some ions can also be regulated by adjusting which fluid on either side of dialysis has a greater conc of each substance. KD takes several hours each session and must be repeated every 1-3 days

Question 29

explain one other treatment of kidney failure

Answer 29

kidney transplant = important that patients and donors tissue match in order to minimise rejection of organ by patients immune system. people can live normally with 1 kidney so its possible for a healthy close family member to donate a kidney if the blood and tissue type match. if family cannot donate patient will go on a waiting list for a kidney from a deceased donor. sometimes waiting list can be long. after recieving transplanted K patient will need to recieve immunosuppressant drugs for rest of their life as well matched kidneys are a perfect tissue match.

Question 30

blood cells, glucose proteins and drugs detected in urinary tests

Answer 30

glucose - healthy = no glucose in urine. glucose that is filtered is normally completely reabsorbed in locations such as PCT
BC - glomerular filtrate = no BC in it because BC are too large to fit through fenestrations of glormerulus, BC in urine = kidney malfunction or infection and bleeding somewhere in the renal tubes
proteins - also too large to get through fenestrations and so shouldnt be found in urine
drugs - into blood stream and filtered by kidneys > common for some employers to test individuals regularly for unauthorised chemicals

Question 31

what happens to glucose levels when someone suffers from diabetes

Answer 31

glucose level rises. known as hyperglycaemia. solute conc of blood rises + indivdual will become very thirsty > glucose also appear in urine as blood sugar levels are so high that kidney cannot reabsorb it. known as glycosuria. common test for diabetes is to measure the level of glucose in the urine

Question 32

explain importance of excretion

Answer 32

removal of waste products that is toxic waste would alter pH
metabollic waste cannot be broken down

Question 33

explain the importance of osmoregulation

Answer 33

it is the regukation of salt and water content which would cause water to enter or leave cells causing cells to shrink/burst which alters BP

Question 34

there is no urea in the dialysis fluid before dialysis begins
give one reason why it is important

Answer 34

so urea can diffuse into dialysis fluid

Question 35

describe how aldoesterone increases BP

Answer 35

sodium ions are reabsorbed into the blood aldosterone acts on DCT
water reabsorbed by osmosis due to decrease in water potential thus increasing BP

Question 36

discuss the + and - of treating kidney failure with kidney transplantation

Answer 36

+
• no need for regular hospital attendance
• increase normal lifestyle
• normal healthy diet
• cost effective

• • shortage of donors
  • not immediate form of treatment
  • risk of surgery
  • transplant may fail

Question 37

explain the effect of ADH on the rate of urine production

Answer 37

ADH leads to reduction of urine because there are more aquaporins so more water is absorbed rather than excreted

Question 38

the blood in renal vein contains less oxygen than the blood in the renal artery
state two other ways that the blood in the renal vein is different from the blood in the renal artery

Answer 38

1 - blood in renal vein is more viscous > less water/glucose in renal vein than renal artery
2 - more urea in renal artery than renal verin > pressure in renal vein less than renal artery

Question 39

explain why it is important that the kidneys regulate the pH of the blood and tissue fluid

Answer 39

• enzyme prevents denaturing so active site still fits substrate
• maintain an approximate pH which prevents pH from becoming too acidic or alkaline
• so metabolism reactions can occur
• affects blood clotting
• organ failure can occur which leads to death