excretion

Question 1

def metabolism

Answer 1

the sum of all the chemical reactions within the body of an organism

Question 2

def excretion

Answer 2

process by which metabolic waste products and toxic substances are removed from the body

Question 3

impt of excretion

Answer 3

metabolic waste products are harmful if accumulated

Question 4

what is excreted via skin

Answer 4

urea, excess water, excess salts (sweat)

Question 5

what is excreted via lungs

Answer 5

carbon dioxide, excess water (expired air)

Question 6

what is excreted via the liver

Answer 6

bile pigments (feces through intestines)

Question 7

what is excreted via the kidneys

Answer 7

urea, excess water, excess salts (urine)

Question 8

func of kidneys

Answer 8

excretion, osmoregulation

Question 9

func of ureters

Answer 9

connects kidney to bladder

Question 10

func of bladder

Answer 10

temporary storage of urine

Question 11

func of urethra

Answer 11

passage through which urine is discharged from the bladder

Question 12

filtrate in ultrafiltration

Answer 12

water, glucose, amino acids, mineral salts, urea

Question 13

residue in ultrafiltration

Answer 13

plasma proteins, blood cells, fats, platelets

Question 14

selective reabsorption: absorbed in the pct

Answer 14

all glucose + amino acids, most water + mineral salts

Question 15

selective reabsorption: absorbed in the loop of henle

Answer 15

some water

Question 16

selective reabsorption: absorbed in the dct

Answer 16

some water + mineral salts

Question 17

selective reabsorption: absorbed in the collecting duct

Answer 17

some water

Question 18

structure of nephron: highly-coiled

Answer 18

incr sa:v, incr time taken for glomerular filtrate to pass through nephron to incr rate of selective reabsorption

Question 19

structure of nephron: dense network of capillaries

Answer 19

incr sa contact and maintain steep conc gradient, incr rate of reabsorption

Question 20

structure of nephron: epithelial cells of coiled tubules contain many mitochondria

Answer 20

release more energy for absorption via AT

Question 21

what happens if kidney fails

Answer 21

excretory products accumulate in the blood

Question 22

dialysis procedure:

Answer 22

1. blood is drawn from a vein in the patient’s arm
2. blood is pumped into the dialysis machine through a tubing
3. the tubing is bathed in a dialysis fluid and is semi-permeable
4. small molecules (urea) + metabolic products diffuse out of the tubing
5. larger molecules (platelets + BCs) remain in the tubing
6. the filtered blood is returned to a vein in the patient’s arm

Question 23

feature of dialysis machine: contains same conc of essential substances as normal blood plasma

Answer 23

ensure no net movement of essential substances from blood into dialysis fluid

ensure substances can flow into patient’s blood if they lack them

Question 24

feature of dialysis machine: metabolic waste products are absent from fluid

Answer 24

establish a steep conc grad to allow excretory products to diffuse into dialysis fluid for removal

Question 25

feature of dialysis machine: long, narrow, coiled

Answer 25

incr sa:v, incr rate of exchange of substances btw blood and dialysis fluid

Question 26

feature of dialysis machine: partially permeable

Answer 26

allow small molecules (urea + mineral salts) to diffuse through tubing but BCs and proteins to be retained in blood

Question 27

feature of dialysis machine: fluid flows in opposite direction to flow of blood

Answer 27

maintain steep conc grad for removal of waste products

Question 28

why is a vein used but not an artery?

Answer 28

ensure continuous input of blood because blood travels in spurts in the artery