Physiology 1 - Intro to Physiology Flashcards
What is Homeostasis?
The ability of the body to maintain a stable internal (cellular) environment
What are the Components of Plasma Membrane?
- Lipid bilayer (phospholipid bilayer)
- Proteins
- integral proteins
- peripheral proteins
Plasma membrane is selectively permeable based on:
- size
- electrical charge
- molecular size
- lipid solubility
What is Osmosis?
the diffusion of water across the cell membrane
What is Diffusion?
the movement of particles across a lipid soluble barrier from an area of higher solute concentration to an area of lower solute concentration
What is the Diffusion Equation?
What is Osmolarity?
the concentration of an osmotic solution
What is Tonicity?
the osmotic pressure of a solution
What is an Isotonic solution?
a solution that does not cause osmotic flow of water in or out of a cell
What is a Hypotonic solution?
has less solutes and loses water through osmosis
A cell in hypotonic solution:
- gains water
- ruptures (lyses)
What is a Hypertonic solution?
has more solutes and gains water by osmosis
A cell in hypertonic solution:
- loses water
- shrinks (crenation)
What are Carrier-Mediated Transport Characteristics (3)?
- Specificity (one transport protein, onse st of substrates)
- Saturation Limits (rate depends on transport proteins, not substrate
- Competition
What is Facilitated Diffusion and how does it work?
- passive
- carrier proteins transport molecules too large to fit through channel proteins (glucose, amino acids)
- molecule binds to receptor site on carrier protein
- protein changes shape, molecules pass through
- receptor site is specific to certain molecules
What is Active Transport? What does it require?
- active transport proteins move substrates against concentration gradient
- requires ATP
What is Cotransport?
two substances move in the same direction at the same time
What is Countertransport?
one substance moves in while the other moves out
What is the Sodium-potassium exchange pump?
- active transport, carrier mediated
- Sodium ions out, potassium ions in
- 1 ATP moves 3 Na out and 2 K in
What are some Examples of Secondary Active Transport?
- Na+-glucose cotransport (symport)
- Na+-Ca2+ countertransport (antiport)
What are the two main types of bulk transport?
- endocytosis
- exocytosis
How does Receptor-mediated endocytosis work?
- Receptors bind target molecules (ligands)
- Coated vesicle (endosome) carries ligands and receptors into the cell
What is Pinocytosis?
endosomes “drink” extracellular fluid
What is Phagocytosis?
engulf large objects in phagosomes
What is Exocytosis?
granules or droplets are released from the cell
What is Transmembrane Potential?
unequal charge across a plasma membrane created by separation of charges
What is the value of Resting potential for most cells?
Ranges from -10 mV to -100 mV
What is the Nernst Equation?
- E = -2.3 RT/zF log10 [Ci]/[Ce]
- Determines electrochemical equilibrium
What are some causes of Isotonic Loss?
decreased intake, vomiting, diarrhea
What are some causes of Isotonic Gain?
retention from kidney disease, overload with IV fluids
What are some causes of Hypotonic Loss?
deficient water, diabetes insipidus, inadequate ADH production, excessive sweating
What are some causes of Hypotonic Gain?
excessive water, SIADH (excess ADH)
What are some causes of Hypertonic Loss?
excess loop/thiazide diuretics, adrenocortical insufficiency
What are some causes of Hypertonic Gain?
salt tabs, excessive salt intake, overload with hypertonic IV fluids (treatment for cerebral edema)
