Osmoregulation and Excretion Flashcards Preview

Bio 121 > Osmoregulation and Excretion > Flashcards

Flashcards in Osmoregulation and Excretion Deck (28):
1

Osmoregulation

Regulation of solute concentrations and balance of gains and losses of water

2

Excretion

Getting rid of nitrogenous metabolites and other waste products

3

Osmolarity

Solute concentration of a solution
Determines movement of water across a selectively permeable membrane

4

Osmoconformers

Some marine animals (mostly invertebrates)
Isoosmotic with surroundings and don't regulate their osmolarity

5

Osmoregulators

Expend energy to control water uptake and loss in a hyperosmotic or hypoosmotic environment

6

Anhydrobiosis

Life without water
Tardigrades: organisms that can live without water for a long time

7

Stenohaline

Animals that cannot tolerate substantial changes in external osmolarity
Humans, insects, most fish, birds, mammals

8

Euryhaline

Animals that can survive having large fluctuations in external osmolarity
Barnacles: euryhaline osmoconformers
Salmon: euryhaline osmoregulators

9

Transport epithelia

Epithelial cells that are specialized for moving solutes in specific directions
Typically arranged in complex tubular networks
Example: nasal glands of marine birds, which remove excess NaCl from blood (salt is secreted through nose and runs down beak)

10

3 main waste products

Ammonia (NH3)
Urea
Uric acid

11

Ammonia as waste

Fish
Excrete small amounts
Need access to large amounts of water
Low metabolic cost to produce
Release this across whole body surface or through gills

12

Urea as waste

Mammals and most adult amphibians
Circulatory system carries this to the kidneys, where it is excreted
More energetically expensive than NH3, but requires less water

13

Uric acid as waste

Insects, land snails, many reptiles, birds
Nontoxic: doesn't harm embryos in eggs
Isn't readily water soluble
Can be excreted as paste with little water loss
More energetically expensive to produce than urea

14

Key functions of most excretory systems

Filtration: filtering of body fluids
Reabsorption: reclaiming valuable solutes
Secretion: adding nonessential solutes and wastes from the body fluids to the filtrate
Excretion: processed filtrate containing nitrogenous wastes is released from body

15

Protonephridia

Excretory system in flatworms
Network of dead-end tubules connected to external openings
Smallest branches of network are capped by cellular units called flame bulbs
Flame bulb contains cillia that direct fluid down tubules

16

Metanephridia

Excretory system in segmented worms
Each segment has pair of these
Consist of tubules that collect coleomic fluid and produce dilute urine for excretion

17

Malpighian tubules

Excretory system in terrestrial arthropods
Remove nitrogenous wastes from hemolymph and function in osmoregulation
Insects produce mainly uric acid: adaptation to terrestrial life

18

Excretory organs of humans

Renal artery and vein connect to kidney
Kidney -> ureter -> urinary bladder -> urethra

19

Flow of fluid through kidneys

Renal cortex (outermost layer) -> renal medulla (chambers between cortex and pelvis) -> renal pelvis (main chamber in middle) -> ureter (tube connecting pelvis with bladder)

20

Nephron types

Cortical nephron: mainly in renal cortex, but a bit in renal medulla
Juxtamedullary nephron: extend from renal cortex into renal medulla

21

Flow of fluid through nephron

Arteriole from renal artery -> Glomerulus -> Bowman's capsule -> proximal tubule -> loop of Henle -> distal tubule -> collecting duct

22

Bowman's capsule

Blood is filtered out of Glomerulus into here
Filtrate produced contains salts, glucose, amino acids, vitamins, nitrogenous wastes, and other small molecules

23

Proximal tubule

Reabsorption of ions, water, and nutrients
As filtrate passes through, materials to be excreted become more concentrated
Molecules are transported actively and passively from filtrate to interstital fluid to capillaries

24

Loop of Henle

Descending: reabsorption of water into interstitial fluid through channels formed by aquaporin proteins; filtrate becomes increasingly concentrated
Ascending: salt diffuses from tubule into interstitial fluid; filtrate becomes increasingly dilute

25

Distal tubule

Regulates K+ and NaCl concentrations of body fluids
Controlled movement of ions contributes to pH regulation

26

Collecting duct

Carries filtrate through medulla to renal pelvis
Reabsorption of solutes and water to interstitial fluid
Some urea is pulled out, but most is excreted
Urine is hyperosmotic to body fluids

27

Antidiuretic hormone (ADH)

Makes collecting duct more permeable to water
Increase in osmolarity triggers release of this, which helps to conserve water
Osmolarity of urine is regulated by hormonal and nervous control
Temporarily increases number of aquaporins in membrane of collecting ducts

28

Diuretic

Inhibits the release of ADH: flush water out rather than reabsorb it