Flashcards in Physiology Deck (52)
What are the components of a phospholipid?
Hydrophobic tail + hydrophilic head
Bonds between phospholipids are strong. True/False?
Bonds are weak - explains the fluid nature of the membrane
Cholesterol contributes to which two aspects of the membrane?
Fluidity and stability
What are the 3 main types of proteins found on the membrane?
Transmembrane (channels, transporters)
The glycocalyx layer is formed by...
Short carbohydrate chains bound to proteins and lipids
What are desmosomes?
Adhering junctions that anchor cells together
What are tight junctions?
Join lateral edges of epithelial cells near their apical membranes
What are gap junctions?
Communicating junctions that allow movement of charge between adjacent cells
2 main factors that influence whether a particle can passively permeate the membrane
Lipid solubility (non-polar pass easily)
Diffusion is movement from ___ to ___ concn
High to low
Fick's law of diffusion describes the rate of net diffusion and is made up of...
Magnitude of concn gradient
SA available for diffusion
Lipid solubility and size/weight of substance
Distance over which diffusion must occur
Osmolarity is defined as...
The number of osmotically active particles present in a solution
How is osmolarity calculated?
Using molar concn (mM) and number of osmotically active particles (n)
150mM NaCl has osmolarity = ?
150 x 2 (Na+ and Cl-) = 300mOsm
A hypotonic solution will ____ in cell volume
Increase (needs mOre water)
Facilitated diffusion requires energy. True/False?
Active transport transfers a substance from high to low concn. True/False?
Low to high
_ Na+ out for every _ K+ in with regards to Na-K pump
Secondary active transport occurs by which 2 mechanisms? Define them
Symport (co-transport): solute and ion move in same direction
Antiport: solute and ion move in opposite directions
Membrane potential (Em) arises due to...
Separation of opposite charges across the membrane
At resting potential, the membrane is 100x more permeable to sodium than potassium. True/False?
100x more permeable to K+ than Na+
Em for K+ is approx...
Em for Na+ is approx...
Eion = 61log[ion]o / [ion]i
Membrane potential is much closer to the potential of Na+ ions. True/False?
Much closer to Ek+ due to greater permeablity of K+
Em for a typical nerve cell at rest = ?
GHK equation (used to calculate membrane resting potential)
Em = 61log x PK+[K+]o + PNa+[Na+]o / PK+[K+]i + PNa+[Na+]i
Which receptors control mean arterial BP? Where are the receptors, control centre + effectors located?
Baroreceptors, located in aortic arch + carotid sinus
Control centre: medulla oblongata
Effectors: heart + blood vessels
Normal range for MAP?