Homeostasis
The relatively constant condition of the body's internal environment.
Homeostasis.
Everything outside the body is called the...
External environment
Body system that exchanges oxygen and carbon dioxide with the blood.
Respiratory system
Organ that stores excess glucose as glycogen.
liver
Fluid that surrounds body cells.
Interstitial fluid.
Homeostasis keeps internal conditions within a _________.
Narrow (acceptable) range
Blood and interstitial fluid together make up the body's....
Body system that adds nutrients to the blood.
Digestive system
Organs that regulate blood volume, salt balance, and pH.
Kidneys
Blood transports oxygen and nutrients to this fluid before they reach cells.
Interstitial fluid
Normal blood pH is approximately...
7.4
The volume and composition of interstitial fluid stay constant only if this remains normal.
Blood composition
Body system that removes metabolic wastes from the blood.
Urinary system
Nitrogenous waste produced by the liver during protein metabolism.
Urea.
Blood vessels where exchanges between blood and tissues occur.
Capillaries.
Normal human body temperature is approximately...
37oC (98.6oF)
Give three examples of values maintained by homeostasis.
Body temperature, blood pH, and blood glucose concentration
Compare the digestive, respiratory, and urinary systems in maintaining homeostasis.
Digestive adds nutrients, respiratory exchanges O₂ and CO₂, urinary removes wastes and regulates water, salts, and pH.
Explain how the liver helps regulate blood glucose.
It removes excess glucose after meals and stores it as glycogen. Later, glycogen is broken down to release glucose into the blood.
Explain why blood composition affects interstitial fluid.
Nutrients, gases, and wastes move between blood and interstitial fluid, so if blood changes significantly, the interstitial fluid changes as well.
Explain why homeostasis is described as "relative constancy" rather than "absolute constancy."
Internal conditions are not perfectly constant—they fluctuate within a normal, acceptable range while remaining stable enough for cells to function properly.
Compare the internal and external environments
The external environment is everything outside the body. The internal environment includes blood, interstitial fluid, cells, tissues, and organs, where conditions are maintained within narrow limits.
Explain how the cardiovascular, digestive, respiratory, urinary, nervous, and endocrine systems work together to maintain homeostasis.
The cardiovascular system transports materials; digestive adds nutrients; respiratory exchanges gases; urinary removes wastes and regulates water, salts, and pH; nervous system provides rapid regulation through nerve impulses; endocrine system provides slower, long-lasting regulation through hormones.
Compare the functions of the liver and kidneys in homeostasis.
The liver regulates blood glucose and produces urea. The kidneys remove metabolic wastes and regulate blood volume, salt balance, and pH.
Describe the pathway of oxygen from the lungs to a body cell.
Oxygen enters the lungs → diffuses into the blood → is transported by red blood cells → moves into capillaries → diffuses into the interstitial fluid → enters the body cell.