excretion ap biology unit 6 osmolarity osmolarity = total solute concentration of a solution which...
TRANSCRIPT
ExcretionExcretion
AP BiologyUnit 6
Osmolarity
• Osmolarity = total solute concentration of a solution
• Which way will the water move?
Slide 2 of 26
Question…
• What would happen if your body did not maintain proper osmolarity?
• You would either have an excess of water (bloated) or too little water (dehydrated)
• Cells wouldn’t have the correct balance of solutes and H2O won’t function properly
Slide 3 of 26
Osmoregulators versus Osmoconformers
Osmoconformers
• Animals whose internal osmolarity changes in relation to their external environment– There are limits to this– too high or too low
will cause death
• Marine invertebrates, sharks, rays
• Ex. Brine Shrimp (Artemia)
Slide 4 of 26
Osmoregulators
• Animals who can maintain their internal osmolarity at a particular level regardless of the external environment
• Ex. Fish, humans, lots of other animals
Slide 5 of 26
Question…
• How does the environment one lives in affect how osmoregulation takes place?– Depending on the environment one lives in,
osmoregulation can be very different
Slide 6 of 26
Saltwater Fish• Challenge: Prevent too much water from
leaving the body (to go into the outside environment)– Higher osmolarity outside compared to inside
of body
• Solution…
Slide 7 of 26
Freshwater Fish
• Challenge: Prevent too much water from coming into the body from the outside– Higher osmolarity inside body compared to
outside
• Solution…
Slide 8 of 26
• Land animals– face the risk of dehydration,– lose water by evaporation and waste disposal, – gain water by drinking and eating, and– conserve water by
• reproductive adaptations, • behavior adaptations,• waterproof skin, and• efficient kidneys.
What about land animals?
© 2012 Pearson Education, Inc.
What is Nitrogenous Waste?• Metabolic waste produced by
cells from the breakdown of Proteins and Nucleic Acids into NH2 groups
• This waste must be excreted
Slide 10 of 26
Figure 25.5
Proteins
Ammonia
Nitrogenous bases
NH2
(amino groups)
Nucleic acids
Urea
Uric acid
Mammals, mostamphibians, sharks,some bony fishes
Birds and many otherreptiles, insects, landsnails
Most aquatic animals,including most bonyfishes
Amino acids
What are the three major kinds of nitrogenous wastes?
• Ammonia: Most toxic. Only produced by aquatic animals
• Urea: Formed by combining Ammonia with CO2; Not as toxic; Released with less water
• Uric Acid: Least soluble; Excreted with the least amount of water
Slide 11 of 26
Excretion in Aquatic Animals
• For most aquatic animals, excreting ammonia is not an issue - why? – Ammonia is highly soluble in H2O, diffuses
away rapidly (won’t stay concentrated around them)
– Aquatic animals continuously lose ammonia from their bodies through diffusion across their gill membranes
Slide 12 of 26
Question…
• Why don’t terrestrial animals and some aquatic animals just excrete dilute ammonia in liquid? – Since ammonia is toxic even at fairly low
levels, it would have to use a lot of water to dilute it
– Too much water loss = dehydration
Slide 14 of 26
Why do some land animals excrete uric acid instead of urea?
• Helps conserve H2O because it isn’t very soluble in water semi solid
• Ex. Birds, reptiles, insects, some amphibians
Slide 16 of 26
Figure 25.7
Reabsorption Secretion Excretion
Urine
To renal vein
Filtration
Nephron tubule
Capillary
Interstitial fluid
H2O, other small molecules
Bowman’s capsule
Fromrenalartery
Stages of Excretion
Excretory Process• Filtration: Initial movement of fluid and solutes
from the body
• Selective Reabsorption: Water and
desirable solutes are reabsorbed into the
body
• Secretion: Excess waste solute is added
to the filtrate
• Excretion: Modified filtrate is expelled
from the body
Slide 17 of 26
Invertebrate: Flatworm Excretory System
• Protonephridia are tiny tubules that interstitial fluid moves through
• Filtrate is produced through the action of ciliated “flame bulb cells”
• Filtrate modified as it flows and exits through openings in the body wall
Slide 21 of 26
Invertebrate: Earthworms
• Due to pressure from blood water and solutes are pushed from the blood into the metanephridia
• Reabsorption and Secretion takes place between metanephridium and capillaries
• Stored urine excreted through external openings
Slide 23 of 26
Vertebrates: What are the major organs of the urinary system?
• Kidneys – produce urine
• Ureters – carries urine from
the kidneys to bladder
• Bladder – stores urine
• Urethra – releases the urine
• Nephrons
– are the functional units of the kidneys,
– extract a fluid filtrate from the blood, and
– refine the filtrate to produce urine.
25.6 The urinary system plays several major roles in homeostasis
© 2012 Pearson Education, Inc.
NephronBlood Processing:1)Filtration: Arteries transport blood to the
kidney (nephron)Urea, water, Glucose, and
salts (minerals) are filtered out by diffusion/active transport
No!! Way too Big!!!
Will blood cells and proteins be filtered into the nephron?
NephronBlood Processing:2) Reabsorption: Substances still needed by the
body are removed from the filtrate and reenter the blood via diffusion/active transport
Ex: glucose, water, minerals (NOT urea)
Nephron
Blood Processing:
3)Secretion:Kidneys remove certain
substances from the blood and add them to the filtrate.
Ex: Salts, Water
Nephron
Blood Processing:
4)Excretion:Urine has been formed! Will
be moved to the bladder to be excreted from the body
© 2012 Pearson Education, Inc.
Animation: Nephron IntroductionRight click on animation / Click play
Figure 25.6
Aorta
Kidney
The urinary system
Inferiorvena cava
Renal artery (red)and vein (blue)
Ureter
Urethra
Urinary bladder
Renal cortex
Renal medulla
Renal pelvis
Ureter
The kidney
Proximal tubule
Bowman’s capsule
Tubule
Collectingduct
To renalpelvis
Branch ofrenal artery
Branch ofrenal vein
Renal cortex
Renal medulla
CapillariesGlomerulus
Distaltubule
Fromanothernephron
Bowman’s capsuleArteriole
from renalartery
Arteriolefrom glomerulus
Branch ofrenal vein
Loop of Henlewith capillarynetwork
Detailed structure of a nephron
1
3
2
Orientation of a nephron within the kidney
Collectingduct
Figure 25.6_1
Aorta
Kidney
The urinary system
Inferiorvena cava
Renal artery (red)and vein (blue)
Ureter
Urethra
Urinary bladder
Figure 25.6_2
Renal cortex
Renal medulla
Ureter
Renal pelvis
The kidney
Figure 25.6_3
Bowman’s capsule
Tubule
Collectingduct
To renalpelvis
Branch ofrenal artery
Branch ofrenal vein
Renal cortex
Orientation of a nephron within the kidney
Renal medulla
Figure 25.6_4
Proximal tubuleGlomerulus
DistaltubuleCollectingDuct
Fromanothernephron
Bowman’s capsule
Arteriolefrom renalartery
Arteriolefrom glomerulus
Branch ofrenal vein
Loop of Henlewith capillarynetwork
Detailed structure of a nephron
Capillaries
1
3
2
25.7 Overview: The key processes of the urinary system are filtration, reabsorption, secretion,
and excretion
• Filtration– Blood pressure forces water and many small
molecules through a capillary wall into the start of the kidney tubule.
• Reabsorption– refines the filtrate,– reclaims valuable solutes (such as glucose,
salt, and amino acids) from the filtrate, and– returns these to the blood.
© 2012 Pearson Education, Inc.
Figure 25.7_1
Filtration
Nephron tubule
Capillary
Interstitial fluid
H2O, other small molecules
Bowman’s capsule
Fromrenalartery
Figure 25.7_2
Reabsorption Secretion Excretion
Urine
To renal veinCapillary
Nephron tubule
• Substances in the blood are transported into the filtrate by the process of secretion.
• By excretion the final product, urine, is excreted via the ureters, urinary bladder, and urethra.
25.7 Overview: The key processes of the urinary system are filtration, reabsorption, secretion,
and excretion
© 2012 Pearson Education, Inc.
Figure 25.7
Reabsorption Secretion Excretion
Urine
To renal vein
Filtration
Nephron tubule
Capillary
Interstitial fluid
H2O, other small molecules
Bowman’s capsule
Fromrenalartery
• Reabsorption in the proximal and distal tubules removes– nutrients,– salt, and– water.
• pH is regulated by– reabsorption of HCO3
– and
– secretion of H+.
25.8 Blood filtrate is refined to urine through reabsorption and secretion
© 2012 Pearson Education, Inc.
• High NaCl concentration in the medulla promotes reabsorption of water.
25.8 Blood filtrate is refined to urine through reabsorption and secretion
© 2012 Pearson Education, Inc.
© 2012 Pearson Education, Inc.
Animation: Bowman’s Capsule and Proximal TubuleRight click on animation / Click play
© 2012 Pearson Education, Inc.
Animation: Collecting DuctRight click on animation / Click play
© 2012 Pearson Education, Inc.
Animation: Effect of ADHRight click on animation / Click play
© 2012 Pearson Education, Inc.
Animation: Loop of Henle and Distal TubuleRight click on animation / Click play
Figure 25.8 Bowman’scapsule
Blood
Nutrients H2ONaCl
Proximal tubule
Somedrugsand poisonsCortex
Medulla
Interstitialfluid Loop of
Henle
H2O
Filtrate composition
Reabsorption
Filtrate movement
Secretion
Distal tubule1
2 NaCl
NaCl
NaCl
UreaH2O
3K
H
Collectingduct
Urine (torenal pelvis)
H2ONaCl HCO3
H2O
Salts (NaCl and others) HCO3
H
Urea Glucose Amino acids Some drugs
HCO3
H
Figure 25.8_1
Blood
Filtrate composition
Reabsorption
Filtrate movement
Secretion
Bowman’scapsule
Nutrients H2ONaCl HCO3
Proximal tubule
Somedrugsand poisonsCortex
Medulla
H
H2O
Salts (NaCl and others) HCO3
H
Urea Glucose Amino acids Some drugs
Figure 25.8_2
Reabsorption
Filtrate movement
Secretion
NutrientsNaCl HCO3
Somedrugsand poisonsCortex
Medulla
Proximal tubule
Interstitialfluid Loop of
Henle
H2O
NaCl
NaCl
NaCl
UreaH2O
Collectingduct
Urine (torenal pelvis)
Distal tubuleH2O
NaCl HCO3
1
3
2
H2O
H HK
• Antidiuretic hormone (ADH) regulates the amount of water excreted by the kidneys by– signaling nephrons to reabsorb water from the
filtrate, returning it to the blood, and– decreasing the amount of water excreted.
• Diuretics– inhibit the release of ADH and– include alcohol and caffeine.
25.9 Hormones regulate the urinary system
© 2012 Pearson Education, Inc.