Download - AP Biology Unit Four Maintaining Homeostasis
![Page 1: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/1.jpg)
AP Biology Unit Four
Maintaining Homeostasis
![Page 2: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/2.jpg)
• BIG IDEA 2: Biological systems utilize energy and molecular building blocks to grow, to reproduce, and to maintain homeostasis.
• BIG IDEA 3: Living systems store, retrieve, transmit, and respond to information essential to life processes.
• BIG IDEA 4: Biological systems interact, and these interactions possess complex properties.
![Page 3: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/3.jpg)
We will cover…..• Feedback control AGAIN!
• Evolutionary development of animal organ systems to control homeostasis with the environment
• Cellular signaling
• Specific systems: endocrine, nervous, immune
• Developmental stages and timing
• Plants – homeostatic mechanisms and how they respond
![Page 4: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/4.jpg)
Organism Organization
• Cells• Tissues• Organs• Organ Systems (not technically in plants)• Organism
The structure of a component of an organism underlies its function.
![Page 5: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/5.jpg)
Homeostasis
• occurs in ALL organisms
• Involves all levels (except unicellular organisms): cells, organs, organisms
• Reflects continuity and change
• Shaped by evolution
• Affected by disruptions
• Defenses evolved to maintain
![Page 6: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/6.jpg)
Remember….
• Body systems coordinate their activities to maintain homeostasis.
![Page 7: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/7.jpg)
• Boseman videos are helpful!
• bit.ly/homeoprezi
http://www.youtube.com/watch?v=TeSKSPPZ6Ik
![Page 8: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/8.jpg)
HOMEOSTASIS
![Page 9: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/9.jpg)
HOMEOSTASIS
abiotic
response
physiological
behavior
biotic
Feedbackloops
environment
disruption
developmentdefenses
Shaped byevolution
Timing andcontrolcontrol
![Page 10: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/10.jpg)
Regulator or conformer?
• Regulators – control internal fluctuations (us)
• Conformers – allow internal conditions to vary with environmental changes (temp in ectotherms)
![Page 11: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/11.jpg)
acclimatization
• An animal’s normal range of homeostasis may change as the animal adjusts to external environmental changes
![Page 12: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/12.jpg)
![Page 13: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/13.jpg)
Video on Feedback Loops
• As you watch, take notes on the basic diagram of a negative feedback loop
• What are the component parts
• Use two biological examples
http://www.youtube.com/watch?v=q_e6tNCW-uk
![Page 14: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/14.jpg)
Negative Feedback Loops
RECEPTOR
STIMULUS
EFFECTOR
RESPONSE
Most feed back loops are
![Page 15: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/15.jpg)
![Page 16: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/16.jpg)
![Page 17: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/17.jpg)
• In mammals, a group of neurons in the hypothalamus functions as a thermostat
• Fever as a response to infection can reset the hypothalamus set point.
![Page 18: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/18.jpg)
Other circulatory adjustments:Countercurrent exchange in temp regulation
• Common in marine mammals and birds
• the heat in the arterial blood leaving the body core is transferred to the venous blood
![Page 19: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/19.jpg)
![Page 20: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/20.jpg)
Other thermoregulatory mechanisms
• Insulation
• Evaporative heat loss
• Behavioral responses
• Regulation of metabolic heat
- endotherms use metabolic heat to
maintain their body temp
- ectotherm gain heat mostly from
environment
![Page 21: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/21.jpg)
Raising temp metabolically
• Mammals and birds regulate rate of metabolic heat production through activity and shivering.
• Some mammals generate heat through nonshivering thermogenesis, rise in metabolic rate produces heat instead of ATP.
• Some mammals have brown fat for rapid heat production.
![Page 22: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/22.jpg)
Negative feedback: control of sugar in the blood
![Page 23: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/23.jpg)
Islets of Langerhans
![Page 24: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/24.jpg)
Positive feedback:oxytocin to induce childbirth
![Page 25: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/25.jpg)
Ethylene in fruit ripening
Has anyone told you to put a banana in the bag with your apples or pears to help them ripen?
![Page 26: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/26.jpg)
Biological Examples of Negative Feedback Loops
• Thermoregulation • Blood Sugar Levels • Osmoregulation • Respiratory Rate• Blood Pressure
![Page 27: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/27.jpg)
Homeostatic mechanisms and organ systems are shaped by evolution.
• Excretory systems deal with osmoregulation (water balance) and excretion of nitrogenous wastes
![Page 28: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/28.jpg)
osmoregulation
Prokaryotes respond via altered gene expression to changes in the osmotic environment
Protists: Many have contractile vacuoles
![Page 29: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/29.jpg)
In Fish
• Freshwater Fish: Water will diffuse into the fish, so it excretes a very hypotonic (dilute) urine to expel all the excess water. Gills uptake lost salt.
• A marine fish has an internal osmotic concentration lower than that of the surrounding seawater, so it tends to lose water and gain salt. It actively excretes salt out from the gills.
![Page 30: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/30.jpg)
![Page 31: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/31.jpg)
dealing with nitrogenous wastes
The excretory system in vertebrates:
- maintains water, salt, and pH balance
- removes nitrogenous wastes (from breakdown of protein and nucleic acids) by filtering the blood
- nitrogenous waste type depends on environment
![Page 32: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/32.jpg)
![Page 33: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/33.jpg)
Excretory system in flatworms
![Page 34: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/34.jpg)
Excretory system in earthworms
![Page 35: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/35.jpg)
In humans
![Page 36: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/36.jpg)
• The kidney works closely with the circulatory system in that the salt content, pH, and water balance of the blood is controlled by the kidneys.
![Page 37: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/37.jpg)
Within the kidney, fluid and dissolved substances are filtered from the blood and pass through nephrons where some of the water and dissolved substances (nutrients) are reabsorbed. The remaining liquid (including toxins) and wastes form urine.
Increasing saltconcentrationdraws water out oftubule.
![Page 38: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/38.jpg)
What homeostatic mechanisms work here?
Concentrated blood (too much salt, too little water) signal receptors in the hypothalamus to stimulate release of ADH (AntiDiuretic Hormone) by the pituitary gland which influences kidney to reabsorbs water, making blood more dilute.
![Page 39: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/39.jpg)
• Alcohol inhibits the release of ADH, causing the kidneys to produce dilute urine.
![Page 40: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/40.jpg)
• If, on the other hand, a person drinks an excess of water, the sodium in the blood becomes more dilute and the release of ADH is inhibited.
• The lack of ADH causes the nephrons to become practically impermeable to water, and little or no water is reabsorbed from them back into the blood.
• Consequently, the kidneys excrete more watery urine until the water concentration of the body fluids returns to normal.
![Page 41: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/41.jpg)
It’s really a salt thing!
![Page 42: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/42.jpg)
Osmoregulation
RECEPTOR
STIMULUS
EFFECTOR
RESPONSE
![Page 43: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/43.jpg)
Development of respiratory systems
![Page 44: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/44.jpg)
The Respiratory System
• The respiratory system:
• - delivers oxygen to and removes CO2 from the circulatory system and eventually the tissues
• - in humans, this occurs in the alveoli of the lungs which are covered in capillaries
• The respiratory system works closely with the circulatory system.
![Page 45: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/45.jpg)
Aquatic organisms such as fish: respiratory system
Less Oxygen in water….
Design of gills important….
![Page 46: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/46.jpg)
Countercurrent exchange
![Page 47: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/47.jpg)
How are lungs perfected for terrestrial living?
![Page 48: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/48.jpg)
lungfish
Transition…..both.
![Page 49: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/49.jpg)
How does structure correlate with the function of the parts?
![Page 50: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/50.jpg)
What homeostatic mechanisms are at work here?
• Breathing is controlled by the medulla of the brainstem. It repeatedly triggers contraction of the diaphragm initiating inspiration.
• The rate of breathing changes with activity level in response to carbon dioxide levels, and to a lesser extent, oxygen levels, in the blood. Carbon dioxide lowers the pH of the blood (water and CO2 make carbonic acid H2CO3).
• Hemoglobin carries oxygen and also can carry bicarbonate ions (form of CO2)..
![Page 51: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/51.jpg)
• There are chemosensors in the carotid artery and the arch of the aorta . The sensors of the aortal are sensitive to the level of oxygen in the blood. Sensors near the medulla are sensitive to the level of carbon dioxide in the blood.
• If oxygen level falls or carbon dioxide levels vary too greatly from the set point, a negative feedback mechanism increases respiratory rate.
![Page 52: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/52.jpg)
![Page 53: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/53.jpg)
Mammals are most sensitive to carbon dioxide levels because the amount of CO2 varies most in respiration in response to different metabolic and environmental conditions.
![Page 54: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/54.jpg)
Circulatory System
• Function – moving substances around: nutrients (from digestion), wastes (from excretion), O2 and CO2 (from respiration), hormones (endocrine), immune substances, and lymph fluid.
• Closely tied to the digestive, excretory, respiratory, endocrine, immune, and lymphatic system.
![Page 55: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/55.jpg)
Types:
• Open – blood mixes with internal organs directly (insects, arthropods, mollusks)
• Closed – blood stays in vessels (earthworms, some mollusks such as octopi, vertebrates
![Page 56: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/56.jpg)
![Page 57: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/57.jpg)
Structures vary for types of animals:
• Fish – one ventricle, one atrium, gill capillaries, single loop
• Amphibian – one v, 2 a, lung and skin capillaries, double circulation (one to body, one to lungs)
• Reptiles – partially divided v, 2 a, other same as amphibs
• Mammal, Birds – 2 v, 2 a, lung capillaries, double circulation
![Page 58: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/58.jpg)
![Page 59: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/59.jpg)
![Page 60: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/60.jpg)
Flow of blood in Mammalian Heart:
right, right, lungs, left, left, body (right side unoxygenated traveling to lungs
the pulmonary artery (arteries – away, veins – toward heart).
R R lungs L L body
![Page 61: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/61.jpg)
![Page 62: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/62.jpg)
![Page 63: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/63.jpg)
Beating of the heart controlled when cardiac muscles transfers an electrical signal via the SA (sinoatrial) node or “pacemaker” (in top right atrium) to the AV (atrioventricular) node between the right a and v.
![Page 64: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/64.jpg)
Blood Pressure Force of blood against an artery.
Measured as Systolic (Super Top Most….when ventricles are contracting) over Diastolic (down, minimum, when ventricles fill with blood); normal 120/80
![Page 65: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/65.jpg)
![Page 66: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/66.jpg)
How does negative feedback loops work here?
For regulating heart beat
• Receptor
• Stimulus
• Effector
• response
![Page 67: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/67.jpg)
Development of Digestive Systems
• Intracellular Digestion – ex amoeba
• Extracellular Digestion – bacteria, us
![Page 68: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/68.jpg)
Digestive Systems in Animals
• One opening – sac (cnidarians, flatworms)
• Tube – roundworms and on
Why more advantageous?
![Page 69: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/69.jpg)
The Digestive System in Humans
• Ingestion, mechanical and chemical breakdown of food, absorption of nutrients, elimination of wastes
![Page 70: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/70.jpg)
![Page 71: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/71.jpg)
Pathway
• Oral Cavity – only carbs broken down here! Mechanical digestion - teeth
• Esophagus – just a muscular tube, peristalsis pushed food down
• Stomach – only protein broken down here! (low pH due to secretion of gastric juice), lots of churning in another muscular organ
![Page 72: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/72.jpg)
The Big Boys…..small intestines and accessory glands
• Carbs, proteins, and lipids broken down here.
• Most digestion and absorption here!
• Pancreatic enzymes and bile (for fat) from the liver via the gallbladder released in this area.
• Microvilli extend the surface area.
![Page 73: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/73.jpg)
Microvilli in the small intestine
![Page 74: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/74.jpg)
Finishing up…
• Large intestine (colon)- no digestion, just reabsorbs water and creates feces
![Page 75: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/75.jpg)
Can you live without your…How?
• Stomach?
• Small Intestine?
• Large intestine?
![Page 76: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/76.jpg)
• How does the homeostatic evolution of these systems reflect:
• Continuity
• Divergence
![Page 77: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/77.jpg)
What about dehydration?And other issues affecting
homeostasis?
http://www.youtube.com/watch?v=zrme9a_GMD8&list=PLFCE4D99C4124A27A&index=27Boseman
![Page 78: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/78.jpg)
Case Study
• The story of Darlene Etienne and her miraculous homeostatic mechanisms!
http://www.reuters.com/article/video/idUSTRE60O29A20100128?videoId=34511738
![Page 79: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/79.jpg)
• "We cannot really explain this because that's just (against) biological facts," Lambert told a news conference. "We are very surprised by the fact that she's alive. ... She's saying that she has been under the ground since the very beginning on the 12th of January so it may have really happened — but we cannot explain that."
• Authorities say it is rare for anyone to survive more than 72 hours without water, let alone 15 days. But Etienne may have had some access to water from a bathroom of the wrecked house, and rescuers said she mumbled something about having a little Coca-Cola with her in the rubble.
• Fuilla said Etienne did not suffer a broken leg, as first reported, but that both legs were trapped under debris. "Both legs are very sore," he said.
![Page 80: AP Biology Unit Four Maintaining Homeostasis](https://reader035.vdocuments.site/reader035/viewer/2022062315/568151ff550346895dc03d3d/html5/thumbnails/80.jpg)
Rescuers said the 16-year-old, who was severely dehydrated and covered in dust, possibly survived by drinking bathwater but could not have lasted much longer.
Earthquake survival stories
http://news.bbc.co.uk/2/hi/americas/8459090.stm