Urinary System

Question 1

urinary system: functions (2)

Answer 1

• excretion

- osmoregulation

Question 2

excretion

Answer 2

• kidneys excrete nitrogenous waste, amino acids, and salts

Question 3

osmoregulation (2)

Answer 3

• kidneys help maintain water balance by keeping water levels and ions within the body at a nearly constant level (often in cooperation with other structures - gills, skin, salt glands)
• specific functions depend on osmoregulatory challenges of the environment

Question 4

vertebrate kidney structure

Answer 4

• contain many nephrons, which are responsible for urine formation

Question 5

nephron filtration

Answer 5

• glomerulus: cluster of very permeable (“leaky”) capillaries where plasma and dissolved substances from blood leak out into the Bowman’s capsule

Question 6

what happens after fluids leak into the Bowman’s capsule (2)

Answer 6

• fluid passes from Bowman’s capsule into the nephric tubule

- substances needed by body (glucose, salts, proteins, water) are reabsorbed into the blood

Question 7

nephron reabsorption (2)

Answer 7

• proximal tube reabsorbs water, nutrients, salts, and transports substances back into blood
• nephric tubule is surrounded by extensive network of capillaries which take up reabsorbed substances (large SA and mitochondria to facilitate transport)

Question 8

nephron active excretion/reabsorption of salts

Answer 8

• in the distal tube, certain salts are actively excreted into the nephric tubule, while others are actively reabsorbed into the blood

Question 9

what is the final product of the nephron system (2)

Answer 9

• urine

- it is drained from the kidney by a duct

Question 10

osmoconformers (2)

Answer 10

• animals that do not osmoregulate

- their bodily fluid is isosmotic to their environment

Question 11

hyperosmotic

Answer 11

• describes the bodily fluids of osmoregulators living in freshwater
• bodily fluids have a higher [ ] of solute molecules than the surrounding water, such that water moves by osmosis into the body

Question 12

hyposmotic

Answer 12

• describes the bodily fluids of osmoregulators living in marine water
• bodily fluids have a lower [ ] of solute molecules than the surrounding water, such that water moves by osmosis out of the body, cause dehydration

Question 13

how do animals osmoregulate

Answer 13

• either actively excrete/uptake ions or water depending on their environment, to maintain their water balance

Question 14

how do freshwater fish osmoregulate (3)

Answer 14

• gills actively take up water and ions
• eat food, don’t drink water
• produce dilute urine

Question 15

how do saltwater fish osmoregulate (3)

Answer 15

• eat food and drink seawater
• gills actively excrete ions
• produce concentrated urine

Question 16

kidney function: freshwater fish/amphibia

Answer 16

• produce dilute urine: glomeruli are enlarged, increasing filtration, and less water is reabsorbed by the nephric tubules

Question 17

kidney function: marine fish

Answer 17

• excrete concentrated urine: kidneys have no glomeruli so there is no filtration and urine is produced by active secretions of substances into the nephric tubules

Question 18

how do chondrichthyes use urea for osmoregulation (2)

Answer 18

• high levels of blood urea increase [ ] of solutes in bodily fluids to make them isosmotic/hyperosmotic to sea water and preventing dehydration
• they must still actively excrete ions

Question 19

osmoregulation in terrestrial tetrapods (2)

Answer 19

• those living in dry environments lose water to the air through evaporation, causing dehydration or desiccation
• kidneys produce highly concentrated urine to conserve water (kidneys still have glomeruli)

Question 20

loop of Henle (3)

Answer 20

• mammals have elongated region of nephric tubule
• helps to produce concentration gradient of salt surrounding the collecting tubules, so water is reabsorbed from collecting tubule and urine is concentrated
• longer loops produce greater ability to concentrate urine and conserve water

Question 21

rectal gland

Answer 21

• chondrichthyes actively remove NaCl from blood and excrete it through a duct into the rectum

Question 22

salt glands (2)

Answer 22

• many sauropsids (marine and dry environments) use specialized salt glands to excrete excess salts
• can be located in the nasal cavity, buccal cavity, or in eye orbit