excretion

Question 1

excretion

Answer 1

the removal of metabolic wastes from the body

Question 2

metabolism

Answer 2

the sum total of chemical reactions that occur in a cell

Question 3

what waste products are formed during metabolism ?

Answer 3

• excess water
• CO2
• nitrogenous wastes (urea ,uric acid)

Question 4

origin of CO2

Answer 4

it is formed as a by-product of cellular respiration

Question 5

origin of excess water

Answer 5

formed as a by-product of cellular respiration and from the intake of fluid and food

Question 6

origin of urea

Answer 6

formed in the liver from the deamination of excess amino acids

Question 7

origin of bile pigments

Answer 7

formed in the liver during the breakdown of haemoglobin

Question 8

origin of uric acid

Answer 8

the end product of metabolism of nucleic acids

Question 9

blood vessels connected to the kidney

Answer 9

aorta-carries oxygenated blood ,food and waste products from the heart
renal artery - carries blood from the aorta to supply the kidneys with oxygen and food and it brings the waste products to the kidney to be excreted
inferior vena cava-carries deoxygenated blood and other substances from the kidneys back to the heart
renal vein -carries deoxygenated blood ,purified of metabolic waste from the kidneys into the inferior vena cava

Question 10

bladder

Answer 10

stores the urine

Question 11

kidney

Answer 11

a excretory organ that filters nitrogenous waste out of the blood and produces urine

Question 12

ureter

Answer 12

carries urine to the bladder

Question 13

urethra

Answer 13

carries urine out of the body

Question 14

what occurs in the hilum

Answer 14

the renal artery that enters the kidney ,the renal vein and ureter that exits the kidney

Question 15

connective tissue membrane that surrounds the kidney

Answer 15

renal capsule

Question 16

reddish brown region directly under the renal capsule

Answer 16

cortex

Question 17

that inner region of the kidney, which is lighter in color and contains tubes which are arranged in groups

Answer 17

medulla

Question 18

nephron

Answer 18

structural and functional units of the kidney , which is made up of 2 parts: malpighian body and renal tubule

Question 19

malpighian body

Answer 19

found on the end of the nephron in the cortex ,

Question 20

what is found in the malpighian body

Answer 20

a double-walled ,cup shaped structure called the bowmans capsule and inside the bowmans capsule is a capillary network of blood vessels called the glomerulus .

Question 21

blood vessels that transport blood TO THE GLOMERULUS

Answer 21

Afferent arteriole

Question 22

blood vessel that transports blood AWAY FROM the glomerulus

Answer 22

Efferent arteriole

Question 23

cells with projections between in which small openings , filtration slits occur

Answer 23

podocytes

Question 24

the cavity between the inner and outer wall of the bowmans capsule

Answer 24

cavity of the bowmans capsule

Question 25

what is in the renal tubule

Answer 25

- the proximal convoluted tubule (found in the cortex ) - the loop of henle( found in the medulla ) - the distil convoluted tubule (found in the cortex)

Question 26

why does the glomerular filtration occur in the malpighian bodies

Answer 26

the diameter of the afferent arteriole is larger than that of the efferent arteriole ,therefore the blood in the glomerulus is under high pressure and this allows for ultrafiltration

Question 27

how is the ultrafine filter formed and what is filtered through it ?

Answer 27

the thin endotheluim with pores lining the blood capillaries of the glomerulus together with the podocyte layer with filtration slits of the bowmans capsule form the ultrafine filter and filtrable parts of the blood are filtered through .

Question 28

what promotes the filtration process

Answer 28

- high blood pressure in the glomerulus - large filtration surface - parmeability of the glomerular membrane

Question 29

explain glomerular filtration

Answer 29

glomerular filtration occurs in the malpighian bodies because the diameter of the afferent arteriole is larger than that of the efferent arteriole ,so the blood in the glomerulus is under high pressure this allows for ultrafiltration. the thin endothelium layer with pores lining the the blood capillaries of the glomerulus and the podocyte layer with filtration slits of the bowmans capsule form the ultrafine filter which filters the filtrable parts of the blood , the blood cells and the plasma proteins are too large to be filtered so they remain in the blood capillaries .The the part of the blood that moves into the bowmans capsule is known as the glomerular filtrate which carries the useful substances and the waste products

Question 30

what is the part of the blood that moves into the bowmans capsule and contains useful substances and waste products

Answer 30

glomerular filtrate

Question 31

tubular reabsorption

Answer 31

the useful substances, which passed the glomerular membrane , need to be reabsorbed and returned back to the bloodstream, this is so that the useful substances dont form part of the urine and be excreted . the filtrate leaves the bowmans capsule and enter the proximal convoluted tubule

Question 32

how is the malpighian body adapted for filtration ?

Answer 32

- the afferent arteriole is wider than the efferent arteriole , which causes a high blood pressure in the glomerulus that promotes filtration - the bowmans capsule is cup-shaped which provides a large surface for filtration - the capillary network of the glomerulus has a large surface area, which increases the efficiency of filtration - podocytes have filtration slits that only allow smaller parts of the blood to filter through

Question 33

adaptions of the proximal convoluted tubule for reabsorption

Answer 33

- the tube is long and convoluted which enlarges the surface for maximal absorption - the peritubular capillary network surrounds the renal tubule so that the reabsorbed substances can easily move into the bloodstream - the cuboidal epithelial cells which line the tubule have many mitochondria to provide energy for active transport - the cuboidal epithelial cells have finger-like projections that increase the absorption surface.

Question 34

excretion of urine

Answer 34

the liquid entering the collecting duct is now called urine.( the urine of a healthy person has only water ,salts and wastes) urine from 2 million nephrons pass through the collecting duct into the renal pelvis the urine moves down the ureter into the bladder where it is stored and is then released through the urethra

Question 35

tubular excretion

Answer 35

waste products, uric acid ,creatinine as well as hydrogen and ammonium ions that are in the blood that could not filter through the bowmans capsule are excreted by active transport into the distal tubule

Question 36

adrenal gland

Answer 36

secretes the hormone aldosterone which travels to the kidneys and helps to control the balance of salts in the blood ,thus controlling blood pressure

Question 37

aldosterone

Answer 37

hormone secreted by the adrenal gland

Question 38

use of aldosterone

Answer 38

helps control the balance of the salts of the blood thus controlling the blood pressure

Question 39

secretion

Answer 39

the release of useful substances that are produces by cells for important functions

Question 40

blood supply to the kidneys

Answer 40

- the renal artery is a branch of the the aorta that the supplies the kidneys with oxygenated blood rich in metabolic waste products - the renal artery enters the kidney through the hilum , the artery branches into smaller arteries .these arteries extend between the pyramids in the direction of the cortex . - they branch further until they form smaller branches called afferent arterioles - one afferent arteriole extends to each bowmans capsule - the afferent arteriole divides to form a capillary network called the glomerulus ,in the bowmans capsule - the the blood capillaries then merge to form a effernt arteriole that transports blood away from the bowmans capsule . - the efferent arteriole then branches again to form a peritubular capillary network ,which surrounds the renal tubule - the peritubular capillaries combine to form venules then larger veins and eventually form the renal vein . - The renal vein takes deoxygenated blood without waste products from the kidney to the heart via the inferior vena cava