Capitolo 1 Flashcards
(62 cards)
What is the primary function of red blood cells in the body?
Red blood cells transport oxygen from the lungs to the tissues.
Why do different types of cells exist in the human body?
Different types of cells exist because each type is specially adapted to perform specific functions.
How do cells generate energy for their functions?
Cells generate energy by using oxygen to react with carbohydrates, fats, and proteins.
What happens when cells of a particular type are destroyed?
The remaining cells of the same type reproduce to replenish the supply.
Where can microorganisms be found in the human body?
Microorganisms inhabit the skin, mouth, gut, and nose.
Why are gut microbiota important for the body?
Gut microbiota are essential for digestion, nutrition, immunity, and other vital functions.
What is the difference between intracellular and extracellular fluid?
Intracellular fluid is the fluid inside the cells, while extracellular fluid is the fluid outside the cells. Extracellular fluid contains large amounts of sodium, chloride, and bicarbonate ions, while intracellular fluid contains more potassium, magnesium, and phosphate ions.
Why is the extracellular fluid called the ‘internal environment’ of the body?
The extracellular fluid is called the internal environment because it provides the essential ions and nutrients that all cells need to maintain life, regardless of their location in the body.
What substances are found in the extracellular fluid that help maintain cell life?
The extracellular fluid contains oxygen, glucose, fatty acids, amino acids, sodium, chloride, and bicarbonate ions, all of which are necessary for cells to function properly.
How is carbon dioxide transported from the cells to the lungs?
Carbon dioxide is transported through the extracellular fluid, which carries the waste products from the cells to the lungs for excretion.
What mechanisms help maintain the differences in ion concentration between extracellular and intracellular fluids?
Special transport mechanisms across the cell membranes help maintain the differences in ion concentrations between extracellular fluid (rich in sodium and chloride) and intracellular fluid (rich in potassium and phosphate).
The differences in ion concentration between extracellular and intracellular fluids are primarily maintained by:
1. Sodium-Potassium Pump (Na⁺/K⁺ ATPase): This active transport mechanism uses ATP to pump 3 Na⁺ ions out of the cell and 2 K⁺ ions into the cell against their concentration gradients. This process maintains high Na⁺ concentration outside the cell and high K⁺ concentration inside the cell, contributing to the cell’s resting membrane potential. 2. Selective Permeability of the Cell Membrane: The cell membrane is selectively permeable to ions, with channels that allow specific ions to pass through. For example, leak channels are more permeable to K⁺ than to Na⁺, allowing K⁺ to exit the cell more readily and further maintaining the concentration gradient. 3. Ion Channels and Transporters: Ion channels, including voltage-gated and ligand-gated channels, allow specific ions to move down their concentration gradients when open. Other transporters, such as calcium pumps and chloride channels, also play a role in maintaining ionic differences. 4. Electrochemical Gradient: The difference in charge across the membrane, or membrane potential, influences the movement of ions. The negatively charged interior of the cell attracts positively charged ions, while repelling negatively charged ions, helping to maintain ionic distribution.
What is the concept of homeostasis, and who coined the term?
Homeostasis refers to the maintenance of nearly constant internal conditions in the body, allowing cells and organs to function properly. The term was coined by the American physiologist Walter Cannon in 1929.
How do the lungs, kidneys, and gastrointestinal system contribute to homeostasis?
The lungs provide oxygen to the extracellular fluid to support cellular functions, the kidneys regulate ion concentrations, and the gastrointestinal system supplies nutrients and removes waste products.
What are some examples of tightly regulated substances in the body, and why is this important?
Hydrogen ions and sodium concentrations are examples of tightly regulated substances. Hydrogen ion concentrations vary by less than 5 nanomoles per liter, while sodium levels vary by a few millimoles per liter. This regulation is critical for maintaining proper cellular functions.
How do diseases disrupt homeostasis, and what are compensatory mechanisms?
Diseases often disrupt homeostasis, but compensatory mechanisms, such as changes in blood pressure in response to kidney dysfunction, help maintain vital functions. However, these compensations can sometimes lead to further health complications over time.
What role does pathophysiology play in understanding homeostasis?
Pathophysiology studies how normal physiological processes are altered by disease or injury, helping to explain how compensatory mechanisms in response to illness can affect the body’s homeostasis.
How is extracellular fluid transported throughout the body?
Extracellular fluid is transported in two stages: first, through the movement of blood in the blood vessels, and second, through the exchange of fluid between the blood capillaries and the intercellular spaces between tissue cells.
What happens during the exchange of fluid between blood capillaries and tissue spaces?
As blood passes through capillaries, fluid and dissolved molecules, except for plasma proteins, diffuse back and forth between the blood and the interstitial fluid, allowing for constant exchange and mixing of extracellular fluid.
Man mano che il sangue passa attraverso i capillari, il fluido e le molecole disciolte, ad eccezione delle proteine plasmatiche, diffondono avanti e indietro tra il sangue e il liquido interstiziale, permettendo uno scambio e un mescolamento costante del fluido extracellulare.
Why can plasma proteins not pass through the capillary walls easily?
Plasma proteins are too large to pass readily through the capillary walls, unlike other smaller molecules, which can easily diffuse between the blood and interstitial fluid.
What role does diffusion play in the movement of extracellular fluid?
Diffusion is driven by the kinetic motion of molecules, which move freely in all directions, ensuring that fluid and substances are evenly distributed and can reach cells quickly, typically within a few seconds.
How does the circulatory system maintain the homogeneity of extracellular fluid?
The continuous mixing of extracellular fluid, both in the plasma and interstitial fluid, helps maintain a uniform distribution of nutrients and other substances throughout the body, ensuring that cells receive what they need.
How does the respiratory system contribute to the origin of nutrients in the extracellular fluid?
The respiratory system allows blood to pick up oxygen from the alveoli in the lungs. This oxygen diffuses rapidly through the thin alveolar membrane into the blood, where it becomes available to cells as a necessary nutrient for cellular processes.
What role does the gastrointestinal tract play in supplying nutrients to the extracellular fluid?
The gastrointestinal tract absorbs nutrients such as carbohydrates, fatty acids, and amino acids from ingested food. These nutrients enter the bloodstream, contributing to the extracellular fluid and nourishing the cells throughout the body.
How does the liver modify substances absorbed from the gastrointestinal tract?
The liver changes the chemical composition of many substances absorbed from the gastrointestinal tract, making them more usable for the cells. Additionally, it eliminates waste products and detoxifies harmful substances ingested by the body.
