Osmoregulation

Question 1

Define osmosis

Answer 1

-passive transport of water across a selectively permeable membrane in response to solute concentration gradients, pressure gradients

Question 2

Define solute concentration

Answer 2

-is measured as osmolarity in millimoles per liter of solution (mOsm/L)

Question 3

Define osmoregulation

Answer 3

-maintaining osmolarity of body fluids

Question 4

Define osmotic pressure

Answer 4

-the minimum pressure which needs to be applied to a solution to prevent the inward flow of water across a semipermeable membrane

Question 5

Define osmoregulators

Answer 5

-keep the osmolarity of body fluids different from that of the environment

Question 6

Define osmoconformers

Answer 6

-Allow the osmolarity of their body fluids to match that of the environment

Question 7

Molecules and ions are… from the body to keep cellular and extracellular fluids isosmotic

Answer 7

Removed

Question 8

In most animals, extracellular fluids are … through… formed from …… and released to the exterior of the animal as …..

Answer 8

-filtered; tubules; transport epithelium(layer of cells with transport proteins in their membrane); urine

Question 9

Define filtration

Answer 9

-small molecules and ions from body fluids or blood non selectively, pass through narrow spaces between cells into the tubule

Question 10

Define reabsorption

Answer 10

-nutrient molecules, some ions and conserved water are returned to the body fluids or blood by transport epithelium

Question 11

Define secretion

Answer 11

-Excess ions and toxic breakdown products are transported selectively from the bodily fluids or blood into the tubule

Question 12

Define release

Answer 12

-urine(nitrogenous wastes, some ions, toxic breakdown products, excreted water) is released into the environment

Question 13

What are things that generally get reabsorbed?

Answer 13

-glucose, amino acids, ions:Na+,K+,Cl-, water, HCO3-

Question 14

What ions generally get secreted and why?

Answer 14

-H+, and K+
-it’s important for maintaining ion and pH balance

Question 15

What gets excreted?

Answer 15

-substances that are unneeded or are in excess
-Wastes such as nitrogen compounds, NH3 (ammonia)

Question 16

Define secretion

Answer 16

-the discharge of wastes from the body fluid into the filtrate
-selective process in which specific small molecules and ions are transported from the blood into the excretory tubules

Question 17

Define excretion

Answer 17

-elimination of substances from the body
-disposal of nitrogen containing waste products of metabolism

Question 18

What are the three main nitrogenous waste products

Answer 18

-ammonia, urea, uric acid

Question 19

In mammals, urine is …. To body fluids

Answer 19

-hyperosmotic(conserves water)

Question 20

Define nephron

Answer 20

-a structure in the kidney; specialized tubule involved in osmoregulation/excretion

Question 21

Describe filtration

Answer 21

At the proximal end, the nephron forms a cuplike structure= Bowman’s capsule which is around a ball of capillaries(glomerus).
Water, amino acids,ions, glucose, and nitrogenous waster molecules are forced from the glomerus into Bowman’s capsule. The fluid in the Bowman’s capsule is called filtrate.
Filtrate travels through the nephron(where reabsorption and secretion occur) and drains into the collecting ducts and renal pelvis–>ureter–>urinary bladder–>urethra

Question 22

afferent arterioles

Answer 22

deliver blood to the glomerulus

Question 23

efferent arterioles

Answer 23

receives blood from the glomerulus; has smaller diameter—> blood “backs up” (dam) in glomerulus, keeping pressure high

Question 24

What is the function of the collecting duct?

Answer 24

To concentrate urine

Question 25

In the distal convoluted tubule, what is reabsorbed and what is secreted

Answer 25

Na+, Cl-, H2O, and HCO3- are reabsorbed K+ and H+ are secreted

Question 26

Describe what occurs in the ascending loop of henle

Answer 26

Na+ and Cl- are reabsorbed(move from tubule to interstitial fluid) As the tubule ascends, Na+ and Cl- are actively transported out of the tubule fluid in tubule has a lower osmolarity as tubule ascends toward cortex Ascending limb is impermeable to water(bc of a lack of aquaporin)

Question 27

Describe the descending loop of henle

Answer 27

Tubule passes through increasingly higher regions of solute concentrations of interstitial fluid in the medulla Thus water moves out from tubule This, then concentrates the filtrate in the tubule

Question 28

Describe the overall functions of Loop of Henle

Answer 28

Sets up a gradient of solutes in interstitial fluid Very high solute concentration towards pelvis of kidney Descending segment is for water reabsoprtion by osmosis Ascending segment is for Na+ and Cl-reabsoprtion

Question 29

Describe the main functions of the proximal tubule

Answer 29

Main function: reabsorption of water, ions, and nutrients back into the interstitial fluid

Question 30

What does the proximal tubule secrete? and what does it reabsorb?

Answer 30

Secretes H= into the filtrate Reabsorbs Na+, Cl-, and K+ along with water, HCO3- and nutrients

Question 31

To conserve nutrients and water, to balance salts, concentrate wastes for excretion, kidney function controls...

Answer 31

Control osmolarity: mainly by adjusting water loss Control total fluid volume: mainly be adjusting Na+ loss Control pH: Mainly by adjusting bicarbonate loss or gain involved with blood pressure and blood volume control Make renin

Question 32

Water reabsorption in the kidney can be regulated by

Answer 32

ADH

Question 33

ADH is released from

Answer 33

pituitary when osmoreceptors(in the hypothalamus) detect an increase in osmolarity of body fluids

Question 34

Angiotensin also stimulates secretion of...

Answer 34

ADH

Question 35

Function of ADH

Answer 35

increases water reabsorption and stimulates thirst

Question 36

Summarize what happens when there is thirst

Answer 36

Too little water in the blood, detected by the hypothalamus More ADH is produced by the pituitary gland More water reabsorbed by the kidneys caused by ADH Blood becomes less concentrated Negative feedback: The hypothalamus detects changes in blood concentration. The pituitary produces less ADH. Blood returns to correct osmotic concentration

Question 37

ANP function

Answer 37

A protein hormone that inhibits the effects of renin (and leads to blood pressure decrease) ANP promotes natriuresis (loss of sodium

Question 38

Give an overview ANP functions

Answer 38

ANP promotes natriuresis Atrial myocytes synthesize, store, and release ANP in response to stretch (indicated by high blood volume)