TOPIC II: CELL PHYSIOLOGY I Flashcards
What is the basic unit of structure and function in the human body?
The cell
The cell is the fundamental building block of all living organisms.
What is homeostasis?
The ability to maintain stable internal conditions in the body
Homeostasis is crucial for the proper functioning of tissues, organs, and systems.
What is the role of the cell membrane?
Structural boundary and active participant in cell interactions
It plays a central role in cellular communication and whole-body homeostasis.
What is the phospholipid bilayer?
Continuous layer around the cell that acts as a barrier to water-soluble substances
It is permeable to lipid-soluble molecules and small molecules like O2 and CO2.
What are transport proteins?
Proteins that facilitate the movement of ions/molecules across the membrane
Includes channel proteins and carrier proteins.
What are gated channels?
Channels that can open or close when signaled
They selectively permit channel-mediated facilitated diffusion.
What are non-gated (leakage) channels?
Channels that are always open
They allow for the continuous movement of ions/molecules.
What is the function of receptor proteins?
Bind specific extracellular molecules (ligands) like hormones
Example: Insulin binds to receptors on skeletal muscle or adipose tissue.
What is the function of enzymes in the cell membrane?
Control chemical reactions on the membrane surface
Examples include acetylcholinesterase and Na+/K+-ATPase.
What are joining proteins?
Anchor the cell membrane to the cytoskeleton or adjacent cells
They form desmosomes, tight junctions, and gap junctions.
What do identifying proteins do?
Identify the cell as ‘self’ or part of the body
Example: Major Histocompatibility Complex (MHC) proteins.
What are membrane carbohydrates?
Glycoproteins and glycolipids that differ for each cell type
They allow cells to recognize each other, such as sperm recognizing egg.
What is passive transport?
Movement of substances across the membrane without energy
It occurs from high to low concentration.
What is osmosis?
Movement of water across a semipermeable membrane
Water moves down its concentration gradient.
What is osmotic pressure?
Pressure required to prevent water movement across a membrane
It is determined by the concentration of solutes in a solution.
What is a hypotonic solution?
ECF has lower osmotic pressure than ICF
Causes cells to swell and potentially burst (lysis).
What happens in a hypertonic solution?
ECF has higher osmotic pressure than ICF
Causes cells to shrink and lose water.
What is an isotonic solution?
ECF and ICF have equal osmotic pressures
Cells neither swell nor shrink.
What is bulk flow?
Movement of fluid and solutes due to a pressure gradient
Examples include filtration and absorption in capillaries.
What is active transport?
Movement of substances against their concentration gradient using energy (ATP)
Always involves protein carrier-mediated processes.
What is primary active transport?
Direct use of ATP in the transport process
Example: Na+/K+-ATPase pump.
What is secondary active transport?
Indirect use of ATP where one substance moves down its gradient driving another against it
Example: Glucose absorption in the small intestine.
What is vesicular transport?
Movement of substances in vesicles surrounded by membrane
Types include endocytosis and exocytosis.
What is phagocytosis?
Endocytosis of large items into the cell
Often referred to as ‘cell eating.’
