homeostasis

• Homeostasis is the stability in the chemical and physical conditions within an organism's cells, tissues, and organs.
• A sensor is a structure that senses some aspect of the external or internal environment.
• An integrator evaluates the incoming sensory information by comparing it to the set point and determines whether a response is necessary to achieve homeostasis.
• An effector is any structure that helps restore the internal condition being monitored by the system.
• Thermoregulation prevents an organism from overheating or experiencing hypothermia due to exchanging heat with their environment.
• Endotherms produces their own body heat, while ectotherms absorb heat from the environment.
• Endoderms maintain a high body temperature at all times due to their high metabolism, which allows them to be active during both winter and night. They can also do high levels of aerobic activities.
• A con of endoderms is that they must eat lots of energy-rich food to support their high metabolism and have to use energy to produce heat instead of other processes.
• Ectotherms can survive off low amounts of food and can use the energy from the food towards growth and reproduction instead of producing heat.
• An ectotherms' metabolism is temperature dependent, slowing down when the temperature drops. So they are less active than endotherms in cold environments or during nights.
• Countercurrent exchange maintains a temperature gradient which allows for a more efficient heat exchange between fluids.
• A cell experiences osmotic stress when the concentration of dissolved substances in a cell or tissue is abnormal.
• In seawater, fish maintain their osmotic balance by drinking large amounts of sea water and actively pumping electrolytes out of their bodies, and producing extremely concentrated urine.
• Freshwater fish have to produce lots of diluted urine and eat or actively transport lots of electrolytes to maintain osmotic balance.
• On land, animals have to constantly eat food to get electrolytes and water to maintain homeostasis.
• To maintain water balance, cells pump ions to set up an osmotic gradient and through osmosis, water follows it across the membrane through aquaporins.
• What is actively pumped in and out of the proximal and distal tubules?

  A) Nacl

  B) H

  C) Nutrients

  D) Nacl

  E) K

  F) H

  G) HCO

  
• What is passively transported out of the descending loop of Henle?

  A) H2O

  
• What is passively transported in and out of the proximal and distal convoluted tubules.

  A) HCO3

  B) H+

  C) H2O

  D) NH3

  E) K+

  F) H2O
• Filtrate includes: HCO3-, urea, salts, water, H+, glucose, amino acids, and certain drugs.
• Water passively flows out of the descending limb of Henle following the osmotic gradient.
• In the thin ascending loop of Henle, Na+ and Cl- passively diffuses out of the nephron and into the interstitial fluid.
• In the thick ascending loop of Henle, Na+ and Cl- are actively pumped out of the nephron and into the interstitial fluid.
• Both the distal tubule and collecting duct are highly regulated and altered in response to osmotic stress.
• Aldosterone affects the distal tubule and collecting duct to increase reabsoprtion of sodium to increase water reabsorption.
• ADH affects the distal tubule and collecting duct to increase water reabsorption to produce less urine.
• The vasa recta and the loop of Henle participate in countercurrent exchange to maintain the osmotic gradient, allowing for water to be reabsorbed back into the body.