Chapter 25

Chapter 25 - Slide 1 Chapter 25: Control of Body...

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Unformatted text preview: Slide 1 Chapter 25: Control of Body Temperature and Water Balance Homeostasis • Maintenance of the internal environment • Three key parts: 1. Thermoregulation: maintaining internal temperatures within narrow limits 2. Osmoregulation: controling the gain and loss of water and solutes 3. Excretion: disposing of nitrogenous wastes Slide 2 Slide 3 Thermoregulation Radiation Convection Evaporation Conduction Thermoregulatory Adaptations 1. Metabolic heat production 2. Insulation 3. Circulatory adaptations 4. Evaporative cooling 5. Behavioral responses Slide 4 1. Metabolic Heat Production Slide 5 2. Insulation Slide 6 3. Circulatory Adaptations • Blood vessel constriction • Blood vessel dilation • Countercurrent heat exchange Slide 7 Slide 8 Blood from body core in artery 35° Blood returning to body core in vein Blood from body core in artery 33°C 30° 27° 20° 18° 10° 9° Blood returning to body core in vein 4. Evaporative cooling Slide 9 5. Behavioral Responses Slide 10 Energy Saving Adaptations • Slide 11 Torpor – state of reduced activity occurring when metabolic rate and/or body temperature decrease • Hibernation: is a state of inactivity and metabolic depression in animals, characterized by lower body temperature, slower breathing, and lower metabolic rate. Hibernating animals conserve food, especially during winter when food supplies are limited, tapping energy reserves, body fat, at a slow rate. It is the animal's slowed metabolic rate which leads to a reduction in body temperature and not the other way around. • Estivation (Aestivation): is a state of animal dormancy, characterized by inactivity and a lowered metabolic rate, that is entered in response to high temperatures and arid conditions. It takes place during times of heat and dryness, the hot dry season, which is often but not necessarily the summer months. • Daily torpor (Temporal heterothermy): In many bat species, body temperature and metabolic rate are elevated only during activity. When at rest, these animals reduce their metabolisms drastically, which results in their body temperature dropping to that of the surrounding environment. This makes them homeothermic when active, and poikilothermic when at rest. Osmoregulation Slide 12 • Usually occurs by moving solutes (because water will move by osmosis) • Two categories of osmoregulation 1. Osmoconformers: same solute concentration in body fluids as surroundings 2. Osmoregulators: body fluid solute concentration is different than surroundings Freshwater Animals Osmotic water gain through gills and other parts of body surface Uptake of some ions in food Uptake of salt by gills Excretion of large amounts of water in dilute urine from kidneys Slide 13 Saltwater Animals Gain of water and salt from food and by drinking seawater Osmotic water loss through gills and other parts of body surface Excretion of salt from gills Excretion of excess ions and small amounts of water in scanty urine from kidneys Slide 14 Land Animals Slide 15 Slide 16 Proteins Nucleic acids Amino acids Nitrogenous bases ΝΗ2 Amino groups Excretion Most aquatic animals, including most fishes Ammonia Mammals, amphibians, sharks, some bony fishes Urea Birds and many other reptiles, insects, land snails Uric acid Liver Functions Slide 17 • Break down amino acids (for energy and recycling) • Prepare nitrogenous wastes for disposal • Make toxins non­toxic (converts toxins to non­toxins that are easy to dispose of) A lot of toxins in the body are not water soluble. • Synthesize bile (bile breaks down the fats to make them water soluble) • Produce proteins for blood clotting Produce proteins responsible for osmotic balance of the blood (regulation) • It helps regulate blood glucos levels Slide 18 Liver Kidneys Liver Intestines Hepatic portal vein Slide 19 Excretory System Aorta Inferior vena cava Renal artery and vein Ureter Urinary bladder Urethra Kidney The Kidney Ureter Slide 20 The Nephron Bowman’s capsule Nephron tubule Renal artery Renal vein Collecting duct To ureter Slide 21 Slide 22 The Nephron (cont) Filtration Nephron tubule H2O, other small molecules Capillary Reabsorption Secretion Excretion Urine Interstitial fluid ...
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