Excretory System

Question 1

Organs in Excretory System

Answer 1

• lungs - CO2
• large intestines - feces, salts (usually with iron/calcium)
• liver - bile pigment (biliruben from Hb breakdown)
• skin - perspiration (salt, water, heat, urea)
• kidneys (main organ of excretion)

Question 2

function of kidneys

Answer 2

responsible for water-solute balance

Question 3

deamination in excretion

Answer 3

deamination occurs ay liver, produces ammonia, ammonia changes to urea and travels to kidneys via blood

Question 4

nucleotide breakdown in excretion

Answer 4

nucleotides (dna/rna) breakdown into uric acid

Question 5

creatine phosphate

Answer 5

creatinine 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 6

nephron

Answer 6

• microscopic structures that make up kidneys
• filters the blood

Question 7

Pressure Filtration

Answer 7

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

Question 8

Selective Reabsorption

Answer 8

• reabsorption of blood components that are needed by the body (pct to peritubular capillaries)
  Involves 2 processes:
  Passive Reabsorption
• occurs when blood components from pct enter pct cells
• no energy (passive diffusion), particles move along concentration gradient
• nutrients, salts, H2O reabsorbed by simple diffusion
• H2O reabsorption is aided by osmotic pressure due to proteins and salts in blood
  Active Reabsorption
• blood components in pct cells leave and enter the capillaries
• nutrients and salts are actively reabsorbed (with ATP)
• H2O follows due to the osmotic pressure generated

Question 9

tubular excretion

Answer 9

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

Question 10

threshold levels

Answer 10

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

Question 11

T-max

Answer 11

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

Question 12

threshold level of urea vs glucose

Answer 12

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

Question 13

diabetes

Answer 13

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

Question 14

ADH

Answer 14

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

Question 15

Aldosterone

Answer 15

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

Question 16

structure that senses low BP and produces renin

Answer 16

juxtaglomerular apparatus (next to glomerulus, near afferent arteriole)

Question 17

renin

Answer 17

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

Question 18

angiotensin converting enzyme

Answer 18

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

Question 19

angiotensin II functions

Answer 19

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

Question 20

Atrial Natriuretic Peptide/Hormone (ADP/ADH)

Answer 20

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 21

permeability of loop of henle to water

Answer 21

ascending limb is impermeable to H2O, descending limb is permeable

Question 22

countercurrent exchange

Answer 22

• 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