Excretory System

Question 1

function of kidneys

Answer 1

responsible for water-solute balance

Question 2

deamination in excretion

Answer 2

amino group + other molecules -> ammonia -> urea
deamination occurs at liver, produces ammonia, ammonia changes to urea and travels to kidneys via blood

Question 3

nucleotide breakdown in excretion

Answer 3

nucleotides (dna/rna) breakdown into uric acid

Question 4

creatine phosphate

Answer 4

creatine phosphate (molecule found in liver, used to store energy by turning ADP to ATP as a last resort) becomes creatinine and is excreted in urine

Question 5

Pressure Filtration

Answer 5

due to glomerular blood pressure of 60 mmHg, blood is filtered at the glomerulus - bowman’s capsule interface

Question 6

tubular excretion

Answer 6

• unwanted substances enter dct from peritubular capillaries (histamines, penicillin, ammonium ion, H+ (regulate pH), creatinine)
• uses active transport

Question 7

threshold levels

Answer 7

the amount of any substance that is reabsorbed by peritubular capillaries is limited to a threshold level (tubular max/T-max)

Question 8

T-max

Answer 8

maximum amount of any substance in the blood after which no more of it will be reabsorbed because carriers are saturated

Question 9

threshold level of urea vs glucose

Answer 9

low t-max for urea, high t-max for glucose (little urea is reabsorbed, lots of glucose reabsorbed)

Question 10

diabetes

Answer 10

• lack of insulin
• increased glucose concentration in blood
• glucose concentration exceeds threshold
• not all glucose will be reabsorbed
• sugary urine

Question 11

ADH function

Answer 11

hormone that increases the permeability of the collecting duct (opens channels) to increase H2O reabsorption to increase blood pressure & decrease solute concentration

Question 12

Aldosterone

Answer 12

hormone that increases Na+ retention and therefore H2O reabsorption to increase blood pressure

Question 13

structure that senses low BP and produces renin

Answer 13

juxtaglomerular apparatus (next to glomerulus, near afferent arteriole)

Question 14

renin

Answer 14

an enzyme that turns angiotensinogen (plasma protein) into angiotensin I during aldosterone production (for BP regulation)

Question 15

angiotensin converting enzyme

Answer 15

an enzyme in the lungs that converts angiotensin I into angiotensin II

Question 16

angiotensin II functions

Answer 16

• vasoconstriction (increase BP)
• causes release of aldosterone by the adrenal cortex

Question 17

Atrial Natriuretic Peptide/Hormone (ADP/ADH)

Answer 17

peptide/hormone produced by cardiac cells in atria (when blood volume increases stretch), inhibits the production of renin and therefore aldosterone, increasing how much Na+ and therefore H2O are excreted, causing decrease in blood volume

Question 18

permeability of loop of henle to water

Answer 18

ascending limb is impermeable to H2O (can not be reabsorb into blood), descending limb is permeable

Question 19

countercurrent exchange

Answer 19

• ascending loop of henle (impermeable to H2O) contains Na+ pumps for active transport
• Na+ is extruded into interstitial space of renal medulla
• increase in salt and urea concentration in medulla - hypertonic
• H2O diffuses out of descending loop of henle due to the concentration gradient generated

Question 20

non-filterable

Answer 20

formed elements (blood cells etc), plasma proteins

Question 21

when is active transport used

Answer 21

• active reabsorption phase during selective reabsorption from pct cells to capillaries (nutrients and salts)
• tubular excretion from capillaries to dct (unwanted substances like histamines, penicillin, ammonium ion, H+, creatinine)
• countercurrent exchange uses active transport (pumps)

Question 22

what situation exceeds threshold levels

Answer 22

threshold level for glucose exceeded with diabetes

Question 23

production & secretion of ADH

Answer 23

produced in hypothalamus, released by posterior pituitary

Question 24

which hormone is released due to sweating

Answer 24

aldosterone

Question 25

how does ADH work

Answer 25

• increased permeability of collecting duct to H2O (opens channels in duct)
• increased H2O reabsorption into blood (dilutes solute and increased blood pressure)
• decreases amount of urine

Question 26

why does alcohol increase excretion

Answer 26

inhibits adh, adh decreases urine by increasing reabsorption of water

Question 27

where is aldosterone released

Answer 27

adrenal cortex

Question 28

aldosterone function

Answer 28

pumps Na+ out of DCT (and loop of henle) into blood, H2O follows due to osmotic pressure

Question 29

aldosterone production

Answer 29

low blood volume & Na+ sensed by juxtaglomerulus apparatus releases renin -> renin breaks down angiotensinogen to angiotensin 1-> ACE in lung breaks down angiotensin 1 into angiotensin 2 -> angiotensin 2 causes release of aldosterone

Question 30

ANP production

Answer 30

stretch of cells in atria sense high blood volume, release anp/anh

Question 31

ANP function

Answer 31

inhibit renin production, decrease in aldosterone, - decrease Na+ retention from dct and loop of henle
- increased Na+ excretion, therefore H2O excretion (H2O follows by osmosis)
- decrease of H2O concentration in blood, less volume