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Chapter 25 Control of Body Temperature and Water Balance - Coggle Diagram
Chapter 25 Control of Body Temperature and Water Balance
Osmoregulation and Excretion
To survive, all animals need to maintain the concentrations of water and solutes in their bodies.
Animals can maintain water balance in 2 ways
osmoconformer: to have body fluids with a solute concentration equal to that of the surroundings
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.
The process by which animals dispose of these metabolic wastes is termed excretion.
Most aquatic animals dispose of their nitrogenous wastes as ammonia (NH3).
Mammals, most adult amphibians, sharks, and some bony fishes excrete urea as the major waste product.
Insects, land snails, and many reptiles, including birds, convert ammonia to uric acid and avoid water loss almost completely.
In humans, the main processing centers of the urinary system are the two kidneys.
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 majority of water in the filtrate is reabsorbed in the proximal tubule. Further water conservation occurs because of a solute concentration gradient in the
When the solute concentration gets too high, receptors in the brain signal the pituitary gland to secrete a hormone called antidiuretic hormone (ADH) into your blood.
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.
In a medical treatment for kidney disease called dialysis, blood is filtered by a machine that mimics the action of a nephron
Like the nephrons of the kidney, the dialysis machine sorts small molecules of the blood, keeping some and discarding others.
Thermoregulation
25.1
Thermoregulation is the homeostatic mechanism by which animals maintain an internal temperature within an optimal range.
Humans, birds and other mammals are endothermic.
Reptiles and fishes and most invertebrates are ectothermic
Ectothermic, meaning that they gain most of their heat from external source.
Endothermic means that they are warmed mostly by heat generated by metabolism.
Metabolic Heat Production
In cellular respiration, the chemical energy of food is converted to ATP, the main source of energy for cells. Energy is also released as heat.
Circulatory Adaptations
Circulatory systems provide a route for heat flow between the body core and body surface. Adaptations that alter blood flow to the surface or trap heat within the core play a major role in thermoregulation.
Insulation
A major thermoregulatory adaptation in mammals and birds is insulation—hair (or fur), feathers, and
fat—which reduces the radiation of heat from an animal to its environment.
Counter heat exchange, warm and cod blood flow in opposite directions in two adjacent blood vessels.
Warm blood (red) from the body core cools as it flows down the legs. But the arteries carrying the warm blood are in close contact with veins conveying cool blood (blue) back toward the body core.
Evaporative cooling occurs when water absorbs heat from the body surface; as the water evaporates, it takes away large amount of body heat.
Behavioral response animals control body temperature by adjusting their behavior in response to the environment.
Coordinated waves of movement in huddles help penguins thermoregulate.