Chapter 40 Flashcards
Osmoregulation
Control of water and solutes within cells (homeostasis)
The process by which an organism regulates the water balance in its body and maintains the homeostasis of the body
What animals do not osmoregulate?
Marine invertabrates
Osmoconformers
Match the environment in terms of concentration of solutes equal and outside the cell
Ex. marine invertabrates
Diffusion
movement of substances from regions of higher concentration to regions of lower concentration, along concentration gradients
Osmosis
Diffusion of water
Osmoconformers
Marine invertebrates would not osmoregulate because seawater is s fairly constant
osmotically & matches solute concentrations within these animals
Osmoregulators
Actively regulate osmolarity inside bodies to achieve homeostasis
Most marine vertebrates are osmoregulators because their tissues are hypotonic to salt water
They must drink large amount of water to replace loss of water which also brings more solutes
Hyperosmotic
Solution inside cells contains
fewer solutes than seawater- lose water by
osmosis & gain solutes by diffusion
Seawater is hyperosmotic
Osmotic stress of freshwater fish
Tissues of freshwater fish are hypertonic to water
– Solution in cells contains more solutes than outside
– Cells gain water through osmosis & lose solutes by diffusion
How do land animals lose water and replace it
- Evaporation
- Produce urine and sweat
Replace it by drinking, ingestion in food, metabolic pathways
Where does osmoregulation occur in land-dwelling vertebrates
Through the kidney (responsible for water and solute balance & excretion of nitrogenous waste)
Pathway of urine
- Formed in kidney
- Transported through ureter to bladder
- Urine transported out of body from bladder through urethra
Nephrons
basic unit of kidney function responsible for water & solute balance
located in outer region of kidney
(cortex); inner region is the medulla
Structure of the nephron
- Renal corpuscle
- Proximal tubule
- Loop of Henle
- Distal tubule
- Collecting duct
Renal corpuscle
filters blood, forming a “pre-urine”
consisting of ions, nutrients, wastes & water
Proximal tubule
epithelial cells reabsorb nutrients,
vitamins, valuable ions & water
Loop of Henle-
establishes strong osmotic gradient
in tissues outside the loop & osmolarity increases as loop descends
Distal tubule
ions & water are reabsorbed
(under control of hormones)
Collecting duct-
tube through which the final filtrate
(urine) leaves the nephron (altered by hormones)
Renal Corpuscle anatomy
Glomerulus: : cluster of capillaries that bring blood to nephron from renal artery
Bowman’s capsule: region of nephron that
surrounds glomerulus
Function of renal corpsucle
filtration device water & solutes forced
out of blood through pores
in glomerulus resulting in
formation of filtrate
What occurs in proximal tubule
Active transport occurs of selected molecules out of filtrate valuable solutes & water are reabsorbed & returned to body.
Three regions of Loop of Henle
- Descending limb
- Thin ascending limb
- Thick ascending limb
Descending limb
highly permeable to water
(aquaporins) but impermeable to solutes
Water leaves descending limb to maintain osmotic pressure
Ascending limb
- Highly permeable to NA+ and Cl-
- moderately permeable to urea
- impermeable to water
Salt leaves ascending limb to maintain osmotic pressure
Distal tube process
The filtrate contains mainly urea and other waste products when it gets to distal tube and it empties filtrate into collecting dust that leads to ureter
Antidiuretic hormone
When dehydrated the brain released ADH
Triggers insertion of aquaporins in collecting duct more permeable to water & large amounts of water reabsorbed
Types of nitrogenous wastes each terrestrial insects, freshwater fishes, and reptiles excrete
Terrestrial insects − uric acid
Freshwater fishes − ammonia
Reptiles − uric acid
Marine fishes - urea
Why must marine bony fishes drink large amounts of seawater?
Marine bony fishes are osmoregulators living in a hyperosmotic environment.
They must compensate from excessive water loss due to hyperosmotic environment
Characteristics of osmoregulating fish
- Osmoregulating marine fish need to expend energy to excrete NaCl due to drinking large amounts of seawater
- Osmoregulating marine fish need to drink large amounts of seawater.
- Osmoregulating marine fish do not need to make special proteins to protect their cells from high urea concentrations in their tissues.
Characteristics of osmoconformers
- Do not lose water to their environment
- Do not absorb as much NaCl from drinking
- Must expend energy to make proteins that protect their cells from the toxic effects of maintaining high urea concentration in their tissues
A mutation that results in the inability of a terrestrial insect to close the spiracles would likely be most disadvantageous in what environment?
Desert because insects would need to temporarily close spiracles to reduce water loss
What is the function of the Loop of Henle in mammalian kidneys?
To create the kidney’s osmotic gradient that permits the reabsorption of water and various solutes
What is the function of antidiuretic hormone, or ADH?
To signal the insertion of aquaporins in the collecting duct, promoting the reabsorption of water, resulting in concentrated urine
Which type of nitrogenous waste would you expect to be produced by embryos inside eggs laid on land?
Uric acid
Biologists have been able to produce mice that lack functioning genes for aquaporins. How would the urine of these mice compare with that of mice with normal aquaporins?
Without aquaporins in the collecting duct, water cannot be reabsorbed, which would result in increased urine volume and decreased urine osmolarity.
In which environment are you most likely to find animals that employ uric acid as their primary form of nitrogenous waste?
Desert
Why is uric acid advantageous for nitrogenous waste excretion in insects?
Due to its water insolubility, where its elimination does not involve much water loss
The movement of substances from the blood into the proximal tubule is known as
Secretion
How is glucose removed from filtrate in the Loop of Henle
Active transport
What is the inner and outer part of the kidney
The inner part is the medulla, and the outer part is the cortex
What is the driving force for the filtration of blood by the renal corpuscle?
Higher pressure in glomerular capillaries than in the surrounding Bowman’s capsule.
Which regions of the nephron function independently of hormonal control for the most part?
Renal corpuscle, proximal tubule, and loop of Henle.
Which waste is excreted by bony fishes, by mammals, and by insects?
Bony fishes - ammonia
Mammals - urea
Insects - uric acid
Are bony fishes osmoregulators or osmoconformers
Osmoregulatory since they are marine invertebrates
Biologists have been able to produce mice that lack functioning genes for aquaporins. How would the urine of these mice compare to that of mice with normal aquaporins?
Higher volume and lower osmolarity because the aquaporins would not absorb the water in the urine, leaving it highly diluted in large quantities, resulting in low osmolarity
What protein is responsible for forming gradients that favor the reabsorption of ions, water, and nutrients in the proximal tubule?
Na+/K+-ATPase
