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Chapter 25 Control of Body Temperature and Water Balance - Coggle Diagram
Chapter 25 Control of Body Temperature and Water Balance
Thermoregulation
Chapter 25.1 An animal's regulation of body temperature helps maintain homeostasis
Thermoregulation
, the homeostatic mechanism by which anomals maintain an internal temperature within an optimal range despite variations in external temperature, is critical to survival.
Endothermic
are the animal that can generate body heat through internal metabolism.
Ectothermic
like reptiles, fishes and most invertebrates get their body heat from external environment.
Endotherms derive body heat mainly from their metabolism; ectotherms absorb heat from their surroundings. Heat exchange with the environment occurs by conduction, convection, radiation, and evaporation.
Chapter 25.2 Thermoregulation involves adaptations that balance heat gain and loss
Adaptations for thermoregulation include the ability to adjust metabolic heat production, insulation, circulatory adaptations, evaporative cooling, and behavioral responses.
Counter-current heat exchange
, warm and cold blood flow in opposite directions in two adjacent blood vessels.
Chapter 25.3 Cooridnated waves of movement in huddles help penguins thermoregulate
penguins continuously left the huddle at the front edge, more joined at the back edge.
Smaller huddles united with other huddles to produce larger huddles. Additionally, all penguins in a huddle took small steps forward in a coordinated fashion, in much the same way that the “wave” moves through a crowd of fans at a football stadium. The forward steps packed the penguins closer together, thereby conducting heat more and more efficiently.
Osmoregulation and Excretion
Chapter 25.4 Animals balance their levels of water and solutes through osmoregulation
Ways animal can maintain water balance:
One way is to be an
osmoconformer
: to have body fluids with a solute concentration equal to that of the surroundings.
The second way to maintain water balance is to be an
osmoregulator
: to have internal solute concentrations that are independent from those of the external environment.
Through the process of osmoregulation, animals control the concentrations of solutes in their cells and bodies and prevent the excessive uptake or loss of water.
Chapter 25.5 Several ways to dispose of nitrogenous wastes have evolved in animals
Ammonia
Most aquatic animals dispose of their nitrogenous wastes as ammonia (NH3).
Because it is so toxic, ammonia can be tolerated only at very low concentrations and must be transported in very dilute solutions.
Urea
mammals, most adult amphibians, sharks, and some bony fishes excrete urea as the major waste product.
Urea, a soluble form of nitrogenous waste, is produced in the vertebrate liver by a metabolic cycle that combines ammonia with carbon dioxide. The main advantage of excreting nitrogenous waste as urea is its very low toxicity.
Uric Acid
Insects, land snails, and many reptiles, including birds, convert ammonia to uric acid and avoid water loss almost completely.
uric acid is a water-insoluble precipitate, and thus water is not used to dilute it.
Uric acid is a relatively nontoxic nitrogenous waste; it can be safely transported and stored in the body and released periodically by the urinary system.
Chapter 25.6 The urinary system plays several major roles in homeostasis
The urinary system excretes wastes and regulates water and solute balance.
Nephrons extract a filtrate from the blood and refine it into urine.
In filtration, blood pressure forces water and many small solutes into the nephron.
In reabsorption, water and valuable solutes are reclaimed from the filtrate.
In secretion, excess H+ and toxins are added to the filtrate.
In excretion, urine leaves the kidneys via the ureters, is stored in the urinary bladder, and is expelled through the urethra.
The filtrate forced into Bowman's capsule flows into the nephron tubule, where it will be processed. Processing occurs in the tree major sections of the nephron:
➊ the proximal tubule
➋ the loop of Henle, a hairpin loop with a capillary network,
➌ the distal tubul
Chapter 25.7 The kidney is a water-conserving organ
How the human kidney concentrates urine
➊ Most of the reabsorption of glucose, amino acids, NaCl, and other valuable solutes occurs in the proximal tubules.
➋ The long loop of Henle carries the filtrate deep into the medulla and then back to the cortex. Water exits the filtrate as it flows down the loop of Henle because the solute concentration of the filtrate is lower than that of the interstitial fluid in the medulla.
➌ Water reabsorption stops just after the filtrate rounds the hairpin turn in the loop of Henle; this is because cells in this section lack aquaporins.
➍ In the distal tubule, water again exits the filtrate by osmosis. NaCl and other molecules are also reabsorbed from the filtrate.
➎ Final processing of the filtrate occurs as the collecting duct carries the filtrate through the medulla. In the medulla, some urea leaks out into the interstitial fluid, adding to the high solute concentration in the interstitial fluid and maintaining the solute gradient. As the filtrate moves through the collecting duct, more water is reabsorbed before the final product, urine, passes into the renal pelvis
Chapter 25.8 Hormones regulate the urinary system
Antidiuretic hormone (ADH)
is one hormone that regulates the amount of water excreted by the kidneys.
ADH binds to receptor molecules on epithelial cells in the collecting ducts of the kidney, leading to a temporary increase in the number of aquaporin proteins in the plasma membrane.
. Because aquaporin proteins form water channels, the net effect is an increased reabsorption of water by the collecting ducts.
Chapter 25.9 Kidney dialysis can save lives
In a medical treatment for kidney disease called
dialysis
, blood is filtered by a machine that mimics the action of a nephron .
A dialysis machine removes wastes from blood and maintains solute concentration.
Dialysis treatment is life sustaining for people with kidney failure. However, the treatment is also costly, time- consuming (4–6 hours three times a week), and must be continued for life—or until the patient undergoes kidney transplantation.