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What are the two important nitrogen compounds found in urine?
What are the two important nitrogen compounds found in urine?
What role do the kidneys play in the excretory system?
What role do the kidneys play in the excretory system?
Which structure is responsible for transporting urine from the kidneys to the urinary bladder?
Which structure is responsible for transporting urine from the kidneys to the urinary bladder?
In which part of the nephron does the majority of reabsorption of water and salts take place?
In which part of the nephron does the majority of reabsorption of water and salts take place?
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Which organism excretes waste products as uric acid using transport epithelium?
Which organism excretes waste products as uric acid using transport epithelium?
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How does water enter the tubule in the excretory system of insects?
How does water enter the tubule in the excretory system of insects?
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What is the primary function of the urinary bladder?
What is the primary function of the urinary bladder?
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Which structure of the kidney contains specialized capillary networks assisting in excretion?
Which structure of the kidney contains specialized capillary networks assisting in excretion?
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What is the primary nitrogenous waste molecule excreted by many birds, including the Roadrunner?
What is the primary nitrogenous waste molecule excreted by many birds, including the Roadrunner?
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How do the loops of Henle in desert mammals, like the Bannertail Kangaroo rat, adapt to their environment?
How do the loops of Henle in desert mammals, like the Bannertail Kangaroo rat, adapt to their environment?
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Which structure in the nephron is responsible for filtering blood and forming a filtrate?
Which structure in the nephron is responsible for filtering blood and forming a filtrate?
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What is a characteristic of the nephrons found in aquatic mammals like Beavers?
What is a characteristic of the nephrons found in aquatic mammals like Beavers?
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What structural feature of the juxtamedullary nephron contributes to its ability to concentrate urine?
What structural feature of the juxtamedullary nephron contributes to its ability to concentrate urine?
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In terms of homeostasis, what is a major adaptation of the kidneys in most birds?
In terms of homeostasis, what is a major adaptation of the kidneys in most birds?
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What role does the collecting duct play in the nephron?
What role does the collecting duct play in the nephron?
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Which type of nephron is primarily associated with long-term water conservation in mammals?
Which type of nephron is primarily associated with long-term water conservation in mammals?
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What form of nitrogenous waste is excreted by the Desert Iguana?
What form of nitrogenous waste is excreted by the Desert Iguana?
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How do freshwater animals like catfish primarily manage their osmotic balance?
How do freshwater animals like catfish primarily manage their osmotic balance?
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What is a notable feature of the nephrons in the Atlantic bluefin tuna?
What is a notable feature of the nephrons in the Atlantic bluefin tuna?
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What is the primary function of active transport in freshwater animals regarding salt balance?
What is the primary function of active transport in freshwater animals regarding salt balance?
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How do desert animals typically conserve water?
How do desert animals typically conserve water?
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Which type of nephron is primarily associated with desert iguanas, impacting their urine's osmotic properties?
Which type of nephron is primarily associated with desert iguanas, impacting their urine's osmotic properties?
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What is a characteristic adaptation of hyperosmotic freshwater fish such as catfish to their environment?
What is a characteristic adaptation of hyperosmotic freshwater fish such as catfish to their environment?
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What does the urine excretion process in desert animals typically aim to achieve?
What does the urine excretion process in desert animals typically aim to achieve?
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Study Notes
Homeostasis
- Homeostasis is maintaining a constant internal environment despite external changes
- Reactions and enzymes work best in specific conditions
Homeostatic Control System
- Receptor: senses changes in the environment
- Control Center: decides how to respond to the change
- Effector: receives a signal, and adjusts accordingly
Regulatory Mechanisms
- Negative feedback: shut off the original stimulus; reduce the intensity
- Positive feedback: increase the original stimulus; make variable farther from the original value
- Homeostatic mechanisms are used to maintain stable internal conditions
Examples of Homeostatic Regulation
- Thermoregulation: maintaining a constant body temperature
- Glucose Regulation: maintaining a constant blood glucose level
- Osmoregulation: maintaining a constant optimal osmotic pressure
- Excretion: removal of nitrogenous waste products
Thermoregulation
- Skin hairs: trap a layer of air above the skin, insulating against heat loss
- Hypothalamus: monitors body temperature and receives information from temperature-sensitive receptors
- Skin hairs lie flat when warm, rise when cold
Control of Blood Glucose
- Two hormones control blood glucose levels: insulin and glucagon
- Both hormones are secreted by the pancreas and transported to the liver in blood
- Insulin lowers blood glucose
- Glucagon raises blood glucose
Osmoregulation
- Process of maintaining salt and water balance
- Osmosis: diffusion of water across a membrane in response to osmotic pressure caused by an imbalance of molecules on either side of the membrane
- Osmotic pressure: tendency of water to move into another solution by osmosis
- Osmolarity: solute concentration of a solution, determines the movement of water across a selectively permeable membrane
- Isosmotic: movement of water is equal in both directions
- Hyposmotic: net flow of water is from hyposmotic to hyperosmotic solutions
Osmoconformers vs Osmoregulators
- Osmoconformers: internal osmolarity is the same as their surroundings; do not actively adjust internal osmolarity
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Osmoregulators: internal fluids are not isotonic to their surroundings
- discharge excess water in hypotonic environments
- continuously take in water in hypertonic environments
Stenohaline vs Euryhaline
- Stenohaline: cannot tolerate substantial changes in external osmolarity; live in either freshwater or saltwater, but not both
- Euryhaline: survive radical fluctuations in osmolarity in their surroundings; either conform to change or regulate internal osmolarity
Osmoregulation in Marine Animals
- Marine bony fish are hypoosmotic to sea water
- Tend to lose water by osmosis and gain salt by diffusion and from food
- Balance water loss by drinking seawater and actively excretes salts
Osmoregulation in Freshwater Animals
- Freshwater animals are hyperosmotic to fresh water
- Tend to absorb water by osmosis, and lose salts by diffusion
- Maintain water balance by excreting large amounts of dilute urine
- Do not drink much water; replaced by food and active uptake across gills
Excretion
- Process of expelling waste products from the body
- Type and quantity of waste products significantly impacts water balance
- Most significant wastes are nitrogenous breakdown products of protein and nucleic acids
Forms of Nitrogenous Wastes
- Ammonia: most aquatic animals use ammonia as a waste product; very toxic and needs lots of water for dilution
- Urea: produced by mammals and amphibians; less toxic than ammonia, needs less water for excretion
- Uric acid: produced by birds, reptiles, insects, and snails; least toxic, can be excreted as a paste; requires less water
Excretory Processes
- Filtration: pressure-filtering body fluids, producing a filtrate
- Reabsorption: reclaiming valuable solutes from the filtrate
- Secretion: adding toxins and other solutes
- Excretion: filtrate leaves the system
Protonephridia (Flame Bulb System)
- System in flatworms
- Dead end tubules connected to external openings
- Cilia in flame bulbs beats, making interstitial fluid filter through openings in the flame cells
- Solutes will be reabsorbed as fluids pass through tubules
- Excess water and wastes are excreted
Metanephridia of Earthworms
- Each segment of earthworms has a pair of open-ended metanephridia
- Coelomic fluid is filtered into nephrostoma
- Useful solutes are reabsorbed into capillaries
- Dilute urine is excreted
Malpighian Tubules
- System for insects and other arthropods
- Salts and uric acids are transported to the tubule from hemolymph
- Water enters lumen by osmosis
- Reabsorption of water, ions, and organic molecules from hindgut into hemolymph
- Wastes are excreted with feces
Vertebrate Kidneys
- Excretory organs of vertebrates; function in excretion and osmoregulation
- Principle site of salt regulation and water balance
- Consists of specialized structures and capillary networks for excretory process
Human Urinary System
- Blood: enters kidney through renal arteries and leaves through renal veins
- Kidneys: produce urine. Urine is a watery solution of waste products, salts, organic compounds, uric acid, and urea
- Ureters: carry urine to the urinary bladder
- Urinary bladder: temporarily stores urine
- Urethra: transports urine to the exterior
Nephron Structure
- Functional unit of the vertebrate kidney
- Long tubule and ball of capillaries (glomerulus)
Pathway of a Filtrate
- Pathway through nephron tubules
Adaptations of Vertebrate Kidneys
- Mammals: juxtamedullary nephron allows high urine concentration
- Desert Mammals: have loops of Henle that extend into medulla to develop steep osmotic gradients; resulting in concentrated urine
- Aquatic Mammals: have nephrons with relatively short loops, thus lower ability to concentrate urine
- Birds: have juxtamedullary nephrons to conserve water, but loops of Henle extend less far into medulla than mammals
- Reptiles: have cortical nephrons to produce urine that is hypoosmotic to body fluids; use uric acid as nitrogenous waste
- Amphibians: excrete dilute urine in freshwater; conserve body fluid by reabsorbing water on land
- Freshwater fish: must constantly excrete excess water; produce large volumes of dilute urine
- Marine bony fish: have fewer nephrons and lack of distal tubule; filtration rates are low and very little urine is excreted
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Description
Explore the concept of homeostasis, which refers to the maintenance of a stable internal environment within the body despite external changes. This quiz covers key elements such as homeostatic control systems, regulatory mechanisms like negative and positive feedback, and examples including thermoregulation and glucose regulation.
