Flashcards in Forces Acting Across the Memrane Deck (21)
What can pass through the capillary easily but not the cell membrane?
Why can membranes be described as dynamic?
They are always being formed and maintained
Dismantled and metabolised
Why are membranes described as flexible?
Fatty acids in vivo behave like oil and can stretch
What does the membrane insulating against?
Electrical charges - so prevents the movement of electrical charges
What type of membrane protein are receptors?
What are the functions of peripheral proteins?
Anchor the membrane to the intracellular cytoskeleton
They connect the cell to the extracellular matrix
Performs signalling functions within the cell
What does an increased protein content in a cell usually correlate with?
A greater cell activity
What are extracellular glycoproteins and glycolipids responsible for?
Self vs non-self recognition
What is defined as the electrochemical gradient?
It is the combination of the difference in ion concentration and the difference in charge across a membrane.
It drives passive movement
How do you calculate the magnitude of diffusion (F)?
Kp x A x (C1-C2)
Where Kp is the permeability coefficient (measuring the ease at which a molecule can pass through a given membrane)
What makes a molecule diffuse easily across a membrane?
Small, hydrophobic/lipophilic, uncharged
Why don't CO2 and urea pass easily across the plasma membrane?
They are lipophilic
What does H2O pass through in the cell?
What causes ligand gated channels to open?
Chemicals such as neurotransmitter or hormones
What is meant by the membrane potential?
The difference in charge between the inside and the outside of the cell - it creates a potential gradient down which ions flow
When does a carrier act as an ATP ase?
When the electrochemical gradient opposes the movement of ions or he molecule
The carrier protein hydrolyses the ATP releasing energy
When is ATP hydrolysed in the sodium potassium pump?
When expelling sodium from the cell
An inorganic phosphate remains attached to the protein
What is osmotic effect determined by?
PARTICLES - not molecules as they could dissociate
What is the measurement of osmolarity?
What is the osmolarity of blood?
It is taken as 300 (rounded from 285)