cell mb

• What is physiology?

  The study of function in living systems
• How is the organization of the body structured?

  It is structured precisely from atom to organism
• What is the hierarchy of organization in the body?

  • Atom
  • Molecule
  • Macromolecule
  • Organelle
  • Cell
  • Tissue
  • Organ
  • Organ system
  • Organism
• What percentage of body weight is total body water?

  60%

  
• How is total body water divided?

  • 1/3: Extracellular fluid (ECF) = 20% body weight
  • 2/3: Intracellular fluid (ICF) = 40% body weight

  
• What is the percentage of plasma in the extracellular fluid?

  25%
• What is interstitial fluid and its percentage of body weight?

  Fluid distributed between cells, accounting for 75% of ECF or 15% of body weight

  
• What are the minor compartments of extracellular fluid?

  • Transcellular fluid (CSF, ocular fluid, joint fluid)
  • Lymph (fluid returned from interstitial fluid to plasma)

  
• What is the percentage of intracellular fluid in body weight?

  40%

  
• What is the total body water in liters?

  42L
• What are the main processes of water movement in the body?

  1. Osmosis
  2. Tonicity
• What is osmosis?

  Water flows through the cell membrane due to concentration differences
• What are aquaporins?

  Highly selective protein channels that allow water to cross the membrane
• What determines the direction of water diffusion during osmosis?

  The concentration of solutes in the solution
• What is osmotic pressure?

  The pressure needed to stop the flow of water through a semipermeable membrane

  
• What does tonicity refer to?

  The effect of a solution on cell volume due to water movement
• What is an isotonic solution?

  A solution with the same solute concentration inside and outside the cell
• What happens in a hypotonic solution?

  Water enters the cell, causing it to swell
• What happens in a hypertonic solution?

  Water moves out of the cell, causing it to shrink
• What is the osmolarity of ICF and ECF?

  Approximately 290 mOsm/L
• What is the role of Na+ in extracellular osmolarity?

  Na+ is the main solute responsible for ECF osmolarity
• What is the role of K+ in intracellular osmolarity?

  K+ is the main solute responsible for ICF osmolarity
• What happens when ECF becomes hypertonic?

  • Water moves from inside to outside the cell
  • The cell shrinks
• What happens when ECF becomes hypotonic?

  • Water enters the cell
  • The cell swells
• What happens when isotonic solutions are administered intravenously?

  • ECF remains isotonic
  • No net movement of water into or out of cells
  • ECF volume increases
• What are the important differences between ECF and ICF?

  • Composition differs significantly
  • No compartment is completely homogeneous
  • Various cell types vary within compartments

  
• What is the composition of the plasmic membrane?

  It consists of lipids, proteins, and carbohydrates
• What is selective permeability in the cell membrane?

  The ability to allow certain molecules to enter or exit while restricting others

  
• What factors affect membrane permeability?

  Solubility in lipids, size, and charge of molecules

  
• What are the types of membrane proteins?

  Peripheral and integral proteins
• What is the fluid mosaic model of the cell membrane?

  • Membrane structure is fluid and asymmetrical
  • Comprised of different molecules (mosaic)
  • Consists of phospholipid bilayer, proteins, and carbohydrates
• What are the types of lipids in the cell membrane?

  Phospholipids, sphingolipids, and sterols (cholesterol)

  
• What is the role of carbohydrates in the cell membrane?

  They are involved in cell-cell recognition and form the glycocalyx
• What is the significance of the lipid bilayer's permeability?

  • Selectively allows entry of some molecules
  • Restricts entry of others
  • Depends on membrane proteins and physical-chemical factors
• What is passive transport?

  Movement of molecules from high to low concentration without energy
• What is facilitated diffusion?

  Diffusion through protein channels from high to low concentration without energy
• What is active transport?

  Movement of molecules against the concentration gradient requiring energy
• What is primary active transport?

  Transport that uses energy from ATP to move substances against a gradient
• What is secondary active transport?

  Transport that uses energy stored from primary active transport to move substances
• What is the Na+/K+ pump's function?

  It maintains osmotic balance by moving Na+ out and K+ into the cell