Membranes Flashcards
What type of molecules are able to easily pass through the membrane?
Lipid soluble
High levels of what ion are present inside the cell membrnae?
Potassium
Name the fluid that surrounds cells
Interstitial fluid
What is diffusion?
Free and random movement of substances to fill the available space evenly
What is osmosis?
Water moving through a membrane to even up concentrations until equilibrium is reached
What is osmolarity?
The number of particles in a solution
What is the osmotic pressure?
The pressure that must be applied to oppose osmosis
What does tonicity compare?
A solution and a cell
What is the role of channel proteins?
Create a selective tunnel that acts as a passage through the membrane - no saturation limit
What is the role of carrier proteins?
Move specific molecules through the membrane in a series of conformational changes
How is energy used in
- primary active transport
- secondary active transport
- directly
2. indirectly
At what voltage is resting potential?
-60mV
What is an action potential?
Successive opening of voltage gated sodium channels
What is depolarisation?
A positive shift in the cells resting potential
What is hyperpolarisation?
A negative shift in a cells resting potential
What is a patch clamp?
An isolated area where the potential difference of the membrane is measured
Describe the structure of a voltage gated sodium ion channel
- 1x24 TransMembrane (TM) domains
- TM domains grouped into 4 “repeats” (SI to SIV) giving the appearance of 4 subunits.
What is hyperkalemia?
- sodium ion channels open when they shouldn’t
- can’t be treated
- periodic paralysis
What is neuromyotonia?
- disease of voltage gated potassium channels
- muscles stay contracted as the channels arent switched off
Give 3 examples of when exocytosis occurs
- hormone release
- digestive enzymes
- ## neurotransmitter release
Give examples of endocytosis
- Phagocytosis: Macrophages engulf invading microbes and aged blood cells
- Pinocytosis: “Cell drinking” droplets of ECF are taken up into cells
What is transcyosis?
- Moving substances through cells
Used for moving substances (e.g. large proteins) from blood across capillary endothelium into interstitial fluid
Which proteins in the liver allow facilitated transport of glucose into the cell?
GLUT2 proteins
What happens in hepatocytes following a meal?
- Binds to its specific receptor and up-regulates production of hexokinase
- Increased rate of conversion of glucose to glucose – 6 – phosphate
- Glucose is metabolised lowering its concentration in the cytosol of the hepatocyte
What is hyperglycemia?
Increased glucose concentration in the blood
