Excretory systems

Question 1

Fish in freshwater (control of water)

Answer 1

In freshwater, the internal salt concentration will be higher. The means water want to flow into the the fish. The fish avoids drinking water and reabsorbs NaCl in the kidneys. Large urine volume and small concentration.

Question 2

Fish in saltwater (control of water)

Answer 2

In saltwater, the salt concentration will be higher outside the fish. This fish drinks a lot of water and has active secretion of Mg2 ions in the kidney. Water wants to flow from their body. The gills excrete salt. Urine is very concentrated.

Question 3

NaCl and H2O reabsorption in proximal tubule

Answer 3

The proximal tubule is a segment in the nephron. Sodium reabsorption via Na+/K+ pump. Water reabsorption via osmosis.

Question 4

NaCl and H2O reabsorption in loop of Henle

Answer 4

Creating a concentrated urine. Descending limb: water-uptake. Ascending limb: sodium-uptake. The active transport of NaCl helps establish osmolarity which creates a concentration gradient that enables water to be reabsorbed from the decending limb.

Question 5

H2O reabsorption in collecting duct (ADH)

Answer 5

When the body is dehydrated, the hypothalamus detects it and releases ADH. ADH binds to receptors in the collecting duct, causing the permeability of the collecting duct to water increase (water reabsoprtion).

Question 6

Osmoreceptors vs baroreceptors

Answer 6

Osmoreceptors detect changes in plasma osmolarity. When osmolarity increases, the receptors stimulates the release of ADH.
Baroreceptors monitor blood pressure. A decrease in blood pressure trigger ADH secretion.

Question 7

RAAS-system components

Answer 7

Renin: produced by the juxtaglomerular
Angiotensin: effect the vascoconstriction
Aldosterone: a steriod hormone that promotes sodium and water reabsorption in the kidneys.

Question 8

Water balance

Answer 8

Water gain: food, drink and metabolism
Water loss: urine, feces, panting and sweat.

Question 9

Osmosis

Answer 9

Water moves from high concentration of water to low concentration of water. The area of lower salt concentration has more water.

Question 10

Ureters

Answer 10

Tubes that transport urine from the kidney to the urinary bladder

Question 11

Urinary bladder

Answer 11

Hollow muscular sac that temporarily stores urine.

Question 12

Ureathea

Answer 12

Tube that carries urine from the urine bladder to the outside of the body.

Question 13

Glomerulus (nephron anatomy)

Answer 13

Blood enters under high pressure, forcing small substances into the nephron.

Question 14

Proximal convulated tube (nephron anatomy)

Answer 14

Reabsorbs ions, water and nutrients and remove toxins.

Question 15

Descending loop of Henle (nephron anatomy)

Answer 15

Allows water to pass from the filtrate into the interstitial fluid

Question 16

Ascending loop of Henle (nephron anatomy)

Answer 16

Reabsorbs NaCl from the filtrate into the interstitial fluid.

Question 17

Distal tube (nephron anatomy)

Answer 17

Secretes and absorbs different ions to maintain blood pH.

Question 18

Collecting duct (nephron anatomy)

Answer 18

Reabsorbs solutes and water from the filtrate.

Question 19

Nitrous waste

Answer 19

1. Urea: soluble in water and toxic
2. Uric acid: not soluble in water and somewhat toxic.
3. Ammonia: soluble in water and toxic