Osmoregulation and Excretion

Question 1

What is a nephron?

Answer 1

the functional unit of a kidney that consists of the Bowman’s capsule, and tubule.

Question 2

From where does blood enter the glomerulus?

Answer 2

the afferent arteriole

Question 3

From where does blood exit the glomerulus?

Answer 3

the efferent arteriole

Question 4

What is the function of the glomerulus?

Answer 4

to bring blood containing water and solutes to the Bowman’s capsule to be filtered

Question 5

What is the Bowman’s capsule?

Answer 5

the glomerular surrounding the glomerulus that removes filtrate from the blood

Question 6

Why does the Glomerular Filtration Rate matter?

Answer 6

restricting it preserves blood volume when neccessary

Question 7

How is the Glomerular Filtration Rate regulated?

Answer 7

constriction of the afferent artery reduces the net filtration pressure, decreasing the GFR

Question 8

Which solutes are filtered into nephrons?

Answer 8

essential ions, glucose, amino acids, smaller proteins and waste

Question 9

What is the proximal tubule and its function?

Answer 9

the primary site of water and solute reabsorption where Na+ is removed via active transport and water follows because of the osmotic gradient

Question 10

What is the loop of Henle?

Answer 10

A loop consisting of an ascending and descending limb that facilitates reabsorption

Question 11

What is the function of the descending limb?

Answer 11

to release H2O from the filtrate via an osmotic gradient creating a concentrated filtrate

Question 12

What is the function of the ascending limb?

Answer 12

it is impermeable to H2O and facilitates active an passive transport of NaCl in the interstitial fluid

Question 13

What is the purpose of a hyper osmotic interstitial fluid surrounding the medulla?

Answer 13

to facilitate osmosis in the descending limb

Question 14

What is the purpose of the final segment of the nephrons tubule, the distal tube and collecting duct?

Answer 14

hormonal control of electrolytes and urine volume

Question 15

What is aldosterone?

Answer 15

a hormone secreted by adrenal glands which activate Na+/K+ pumps

Question 16

What is the function of Na+/K+ pumps?

Answer 16

reabsorb Na+ and secrete K+ to regulate the osmotic gradient

Question 17

What is the function Anti-Diuretic Hormone (ADH)?

Answer 17

to activate aquaporin vesicles in the collecting duct to perform water reabsorption

Question 18

What is ADH secretion controlled by?

Answer 18

the hypothalamus

Question 19

Where does aldosterone come from?

Answer 19

the adrenal glands activated by ADH

Question 20

What are excretory adaptations?

Answer 20

adaptation of nephrons for osmoregulation in extreme environments

Question 21

Why is a long loop of Henle adaptive?

Answer 21

it produces more concentrated urine limiting the need for water

Question 22

What is the purpose of osmoregulation?

Answer 22

to maintain a water and solute homeostasis because too much of either one would cause cells to expand or dehydrate

Question 23

What is anhydrobiosis and what is an example?

Answer 23

A state of dormancy preventing desiccation/dehydration
tardigrades

Question 24

How are solutes prepared for excretion?

Answer 24

the body metabolizes nucleic acids and proteins into ammonia groups to convert into nitrogenous waste

Question 25

In what form do fish excrete nitrogenous waste and why?

Answer 25

as ammonia because no conversion is required due to the water surrounding them that dilutes it

Question 26

In what form do mammals excrete nitrogenous waste and why?

Answer 26

Urea; it is less toxic and they have occasional access to water; however, it requires conversion in the liver

Question 27

In what form do birds, reptiles, insects, and land snails excrete nitrogenous waste and why?

Answer 27

Uric acidit is nontoxic and they have minimal access to water; however requires a lot of energy to produce

Question 28

What is the first step of the excretory system?

Answer 28

filtration; when water and solutes enter the system from the bloodstream

Question 29

What is the second step of the excretory system?

Answer 29

reabsorption; valuable substances are reabsorbed into the blood stream

Question 30

What is the third step of the excretory system?

Answer 30

secretion, excess or toxic substances are secretion from the bloodstream into the filtrate

Question 31

What is the fourth step of the excretory system?

Answer 31

excretion; the filtration (urine) is excreted from the body

Question 32

How does the digestive tract of an annelid work?

Answer 32

cilia draw water into collecting tubules of the metanephridra and then, waste it is excreted from external pores

Question 33

How does the digestive tract of an arthropod work?

Answer 33

components connected to the digestive tracts known as malpighian tubules reabsorb most solutes and water so no filtration is required