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Questions and Answers
How do freshwater animals primarily manage their water balance?
How do freshwater animals primarily manage their water balance?
What is the term used for the dormant state some aquatic invertebrates enter when losing almost all their body water?
What is the term used for the dormant state some aquatic invertebrates enter when losing almost all their body water?
Which of the following strategies do desert animals primarily use to save water?
Which of the following strategies do desert animals primarily use to save water?
In the water balance comparison, how much water does a kangaroo rat lose through urine daily?
In the water balance comparison, how much water does a kangaroo rat lose through urine daily?
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Which anatomical feature helps seabirds eliminate excess salt from their bodies?
Which anatomical feature helps seabirds eliminate excess salt from their bodies?
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Which component is crucial for animals to regulate their osmotic balance?
Which component is crucial for animals to regulate their osmotic balance?
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Which of the following waste products primarily affects an animal's water balance related to its habitat?
Which of the following waste products primarily affects an animal's water balance related to its habitat?
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What is a key difference between water balance strategies in kangaroo rats and humans?
What is a key difference between water balance strategies in kangaroo rats and humans?
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What is the primary role of filtration in excretory systems?
What is the primary role of filtration in excretory systems?
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Which structure is found in protonephridia and plays a role in excretion?
Which structure is found in protonephridia and plays a role in excretion?
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How do metanephridia function in earthworms?
How do metanephridia function in earthworms?
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What is a notable feature of Malpighian tubules in insects?
What is a notable feature of Malpighian tubules in insects?
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What role do kidneys play in vertebrates beyond excretion?
What role do kidneys play in vertebrates beyond excretion?
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What is the main function of the glomerulus within a nephron?
What is the main function of the glomerulus within a nephron?
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Which statement best describes the selective nature of filtration in the nephron?
Which statement best describes the selective nature of filtration in the nephron?
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Which component of the urinary system transports urine from the kidneys to the bladder?
Which component of the urinary system transports urine from the kidneys to the bladder?
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Which nitrogenous waste product is mainly excreted by mammals and most amphibians?
Which nitrogenous waste product is mainly excreted by mammals and most amphibians?
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Which group of animals predominantly excretes uric acid?
Which group of animals predominantly excretes uric acid?
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What is one reason why uric acid excretion is advantageous for certain organisms?
What is one reason why uric acid excretion is advantageous for certain organisms?
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How does the conversion of ammonia to urea compare in terms of energy expenditure?
How does the conversion of ammonia to urea compare in terms of energy expenditure?
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In excretory systems, what does the term 'refining a filtrate' refer to?
In excretory systems, what does the term 'refining a filtrate' refer to?
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Which nitrogenous waste is considered the most toxic?
Which nitrogenous waste is considered the most toxic?
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Which of the following excretory products indicates a high level of conservation of water in excretion?
Which of the following excretory products indicates a high level of conservation of water in excretion?
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What is a common trait of excretory systems across different species?
What is a common trait of excretory systems across different species?
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What is the primary role of osmoregulation in animals?
What is the primary role of osmoregulation in animals?
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How do freshwater animals adapt to their environment regarding osmoregulation?
How do freshwater animals adapt to their environment regarding osmoregulation?
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What is the difference between isoosmotic and hypoosmotic solutions?
What is the difference between isoosmotic and hypoosmotic solutions?
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What challenge do marine bony fishes face related to osmoregulation?
What challenge do marine bony fishes face related to osmoregulation?
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Which group of animals primarily acts as osmoconformers?
Which group of animals primarily acts as osmoconformers?
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What defines euryhaline organisms in relation to osmotic challenges?
What defines euryhaline organisms in relation to osmotic challenges?
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Why do osmoregulators expend energy?
Why do osmoregulators expend energy?
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What results from the movement of water between hypoosmotic and hyperosmotic solutions?
What results from the movement of water between hypoosmotic and hyperosmotic solutions?
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What substances are primarily reabsorbed during the process in the proximal tubule?
What substances are primarily reabsorbed during the process in the proximal tubule?
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How does the ascending limb of the loop of Henle affect the filtrate?
How does the ascending limb of the loop of Henle affect the filtrate?
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What role do vasa recta play in the kidney's function?
What role do vasa recta play in the kidney's function?
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What is the primary function of the distal tubule in the nephron?
What is the primary function of the distal tubule in the nephron?
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What adaptation do juxtamedullary nephrons provide for terrestrial animals?
What adaptation do juxtamedullary nephrons provide for terrestrial animals?
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What effect does the collecting duct have on the filtrate?
What effect does the collecting duct have on the filtrate?
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Which statement accurately describes the overall kidney function?
Which statement accurately describes the overall kidney function?
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What causes water reabsorption in the descending limb of the loop of Henle?
What causes water reabsorption in the descending limb of the loop of Henle?
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Study Notes
Module BL1004: Animal Physiology
- Module is about animal physiology
- Professor is Rob McAllen
- Email: [email protected]
- Office hours are by appointment
Osmoregulation and Excretion
- Animal excretory systems are discussed
- Chapter 44, page 1029 of Campbell is cited
Overview: A Balancing Act
- Animal physiological systems operate in a fluid environment
- Water and solute concentrations must be maintained within narrow limits
- Osmoregulation maintains solute concentrations and balances water gain and loss
Overview: A Balancing Act (cont.)
- Freshwater animals reduce water intake and conserve solutes due to adaptations
- Desert and marine animals face desiccating environments that can deplete body water quickly.
- Excretion gets rid of nitrogenous metabolites and other waste products
Osmoregulation Balances the Uptake and Loss of Water and Solutes
- Osmoregulation is based on controlling the movement of solutes between internal fluids and the external environment
- Cells require a balance between osmotic gain and loss of water
- Osmosis is the movement of water across a selective permeable membrane
- Osmolarity is the solute concentration of a solution, which determines water movement across a selective permeable membrane
- Isoosmotic solutions have equal water movement in both directions
- A net flow of water moves from the hypoosmotic solution to the hyperosmotic solution
Osmotic Challenges
- Osmoconformers, some marine animals, are isoosmotic with their surroundings and do not regulate osmolarity
- Most marine invertebrates are osmoconformers
- Stenohaline versus Euryhaline tolerances in Osmoconformers & regulators
- Relationship between body fluid osmolality and medium concentration in Tigriopus brevicornis and Artemia nauplii
Osmotic Challenges (cont.)
- Osmoregulators expend energy to control water uptake in a hypoosmotic environment and loss in a hyperosmotic environment
- Marine bony fish are hypoosmotic to seawater
- They lose water via osmosis and gain salts by diffusion and from food
- They balance water loss by drinking seawater and excreting salts
Osmotic Challenges (cont.)
- Freshwater animals constantly take in water by osmosis from their hypoosmotic environment
- They lose salts by diffusion, maintaining water balance by excreting large amounts of dilute urine
- Salts lost by diffusion are replaced in food and by uptake across the gills
Animals That Live in Temporary Waters
- Some aquatic invertebrates in temporary ponds lose almost all their body water and survive in a dormant state
- This adaptation is called anhydrobiosis
Osmotic Challenges (Land Animals)
- Land animals manage water budgets by drinking and eating moist foods, using metabolic water
- Desert animals conserve water via nocturnal lifestyles, underground existence, etc.
Water balance in two terrestrial mammals
- Water balance in a kangaroo rat versus in a human
- Ingested in food and liquid, derived from metabolism, water loss in feces and urine, balance of evaporation
- Data is provided in the form of diagrams
Conservation of water
- Kidneys in animals such as the kangaroo rat are adapted to minimize water loss by concentrating urine
- Dry feces from the kangaroo rats are compared to lab rats' feces
- Uric acid requires less water than urea to rid the same amount of waste
Storage of Water
- Animals store water in fatty deposits in their tails and other tissues.
- Most water is obtained from food
Energetics of Osmoregulation
- Osmoregulators expend energy to maintain osmotic gradients
- Animals regulate the composition of body fluid that bathes their cells
- Transport epithelia regulate solute movement
- These are vital to osmotic regulation and metabolic waste disposal
- They are arranged in complex tubular networks
How do seabirds eliminate excess salt from their bodies?
- Seabirds use salt glands to remove excess sodium chloride from their blood
- Nasal salt glands in seabirds are illustrated
An animal's nitrogenous wastes reflect its phylogeny and habitat
- The type and quantity of an animal's waste products greatly affect its water balance
- Nitrogenous breakdown products of proteins and nucleic acids are important waste products
Nitrogenous wastes
- Ammonia is toxic and requires large amounts of water. Common in aquatic species
- Urea is less toxic and requires less water for excretion. It is produced in the liver of mammals and amphibians
- Uric acid is insoluble in water and can be secreted as a paste with little water loss. This is found in insects, land snails and reptiles (including birds). It is more energetically expensive than urea.
Diverse excretory systems are variations on a tubular theme
- Excretory systems regulate solute movement between internal and external environments
- Most excretory systems refine a filtrate derived from body fluids to produce urine
- Key functions include filtration, reabsorption, secretion, and excretion
Excretory Systems
- Systems that perform basic excretory functions vary among animal groups. Typically involve complex networks of tubules
- Includes Protonephridia (flame cells/planaria), Metanephridia (earthworm/similar to nephrons), Malpighian Tubules (insects), and Nephrons (function unit of the human kidneys)
Protonephridia
- A network of dead-end tubules connected to external openings
- Smallest branches are capped by flame bulbs
- These tubules excrete dilute fluid and function in osmoregulation
Metanephridia
- Each segment of an earthworm has a pair of open-ended metanephridia
- Both excretory and osmoregulatory functions
- Metanephridia consist of tubules that collect coelomic fluid, produce dilute urine
Malpighian Tubules
- In insects and other terrestrial arthropods, Malpighian tubules remove nitrogenous wastes from hemolymph and function in osmoregulation
- Open into the digestive tract, producing relatively dry waste matter for terrestrial life
- Highly efficient in water conservation
Kidneys
- Kidneys, excretory organs of vertebrates, function in both excretion and osmoregulation
- Mammalian excretory systems center on paired kidneys which are primary site for water and salt regulation
- Each kidney is supplied by renal artery and drained by renal vein
- Urine leaves through ureters
- Ureters drain into urinary bladder, and urine is expelled via the urethra
Kidneys: Nephrons
- The nephron is the functional unit of the vertebrate kidney
- Consists of a single long tubule and a ball of capillaries (glomerulus)
- Bowman’s capsule surrounds the glomerulus, receiving filtrate from the glomerulus capillaries
Filtration : Glomerulus --> Bowman's Capsule
- Filtration occurs as blood pressure forces fluid from the blood in the glomerulus to the Bowman’s capsule
- Filtration of small molecules is non-selective
- The filtrate contains salts, glucose, amino acids, vitamins, nitrogenous wastes, and other small molecules
Pathway of the Filtrate
- From Bowman's capsule, the filtrate passes through three regions of the nephron: proximal tubule --> loop of Henle --> distal tubule
- Fluid from several nephrons flows into a collecting duct, then the renal pelvis, and finally the ureter
Pathway of the Filtrate (cont.)
- Vasa Recta are capillaries that serve the loop of Henle.
- The vasa recta and loop of Henle function as a countercurrent system.
- The mammalian kidney conserves water by producing urine more concentrated than body fluids
The nephron is organized...
- Reabsorption of ions, water, and nutrients takes place in the proximal tubule
- Molecules are actively or passively transported from the filtrate into interstitial fluid, then capillaries
- Toxic materials are secreted into the filtrate
- Filtrate volume decreases
The nephron is organized... (cont.)
- Reabsorption of water continues through channels formed by aquaporin proteins driven by high interstitial osmolarity compared to filtrate
- Filtrate becomes increasingly concentrated in the descending limb of the loop of Henle
- In the ascending limb, salt, but not water, diffuses from the tubule into the interstitial fluid
- Filtrate becomes increasingly dilute in the ascending limb
The nephron is organized... (cont.)
- The distal tubule regulates K+ and NaCl concentrations of body fluids
- Collecting duct carries filtrate through the medulla to the renal pelvis
- Water, salt, urea are lost
- Urine is hyperosmotic to body fluids
The nephron is organized... (cont.)
- Human kidneys process approximately 180 liters of filtrate per day
- 99% of water and nearly all sugars, amino acids, vitamins are reabsorbed
Adaptations of the Vertebrate Kidney to Diverse Environments
- The form and function of nephrons vary based on requirements for osmoregulation in an animal's habitat
- The juxtamedullary nephron contributes to water conservation in terrestrial animals
- Mammals in dry environments have long loops of Henle; freshwater mammals have shorter loops
Adaptations of the Vertebrate Kidney to Diverse Environments (cont.)
- Birds and other reptiles have shorter loops of Henle but conserve water by excreting uric acid instead of urea
- Other reptiles have only cortical nephrons but still excrete nitrogenous waste as uric acid
Acknowledgements
- Majority of text and PowerPoint slides from Campbell's Biology
- Dr Ramiro Crego, School of BEES
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Description
Explore the fascinating world of how different animals manage their water balance through various adaptations and anatomical features. This quiz covers topics from freshwater and desert animals to the roles of kidneys and other excretory structures. Test your knowledge on the strategies animals utilize to survive in diverse habitats!
