Cell membrane, cell excitation and synaptic transmission Flashcards
What are the major fluid compartments in the human body?
The major fluid compartments are
- blood plasma (extracellular fluids)
- interstitial fluid (extracellular fluids)
- intracellular fluid
The blood plasma is contained within the blood vessels with a two compartment capillary wall containing it, the interstitial fluid is then found and separated from the intracellular fluid through the cell membrane.
What is the estimated volume of the extracellular fluid?
The extra cellular fluid makes up 20% of the bodily fluid with blood plasma having a 5% volume and interstitial fluid making up 15%.
What is the estimated volume of intracellular fluid?
the intracellular fluid has a volume of 40%.
What is the osmotic equilibrium?
This is the process of water moving freely through each of the compartments until it is equal across the body forming an equilibrium.
- water is gained through consumption
- water is lost through excretion and the lungs
What is the main composition of the cell membrane?
- The cell membrane is made up of a phospholipid bilayer (7.5 nm) composing of a hydrophilic head and a hydrophilic tail (two fatty acid chains).
- The fluid mosaic model describes it will each component had together by van Der Waals forces allowing lateral movement (fluid) in a mosaic arrangement.
- main components are proteins (intrinsic and extrinsic), phospholipids, glycoproteins and cholesterol.
What is the main functions of the cell membrane?
- Act as protection for the cell
- partially permeable to allows for movement of specific material.
- communication with other cells
What is the concentration of ions in the intracellular fluids?
The intracellular fluid contains low amounts of sodium ion and chlorine ion, and a high amount go potassium ions and proteins.
Na+ = 14 mM
Cl- = 9 mM
K+ = 157mM
Proteins = high (needed to catalyse cell reaction)
What is the concentration of ions in the extracellular fluid?
- The blood plasma it contains high amount of Na+ (152 mM) and Cl- (113 mM) and low amounts of potassium ions (5 mM) and proteins.
- the interstitial fluid it contains high amount of Na+ (143 mM) and Cl- (117 mM) and low amounts of potassium ions (4 mM) and proteins (even less then blood plasma).
Why is there a difference in ions concentrations between the body fluid compartments?
This chemical disequilibrium is due to the cell membranes permeability to molecules which varies dramatically.
- highly permeable to water (osmotic equilibrium) and small hydrophobic non polar molecules
- larger polar molecules are transported via transport proteins and channels.
What is the process of diffusion?
Dissuasion os the net movement of molecules down a concretion gradient across a partial permeable or open system.
(H20 molecules move at 2,500 km/h only 0.3 nm apart the constant collision causes movement from high to low concentrations)
What is the process of filtration?
Filtration is the process of small particles moving through pores in the cell membrane due to differences in pressure.
e.g. in the kidneys were high pressure causes phosphate ions to move into low pressure environments and are excreted in urine whilst larger proteins remain.
What is the process of carrier mediated transport?
This has the process of carrier and channel proteins facilitation the flow of substances that cannot permeate a lipid bilayer (large polar molecules) down a concentration gradient.
- carrier proteins allows the molecule to combine with the carrier molecule (specific bonding sites) and go through compositional changes to allow it through the membrane.
- Channel proteins open at one side allowing molecule to enter and then they are released into the cell.
What is the process of exocytosis?
The process of proteins and very large molecules entering the cell, they invaginate into the cell membrane (trapped) the membrane then pinches it off and creates a vesicle which is released into the cell.
- pinocytosis (fat uptake)
- phagocytosis (engulf of pathogens)
What is the process of endocytosis?
Vesicles containing the large molecule of proteins fuse to the cell zebrine inside the cell, then releases the contents outside.
e.g. releases of hormones/neurotransmitters
What is the process of osmosis?
The net movement of water across a partial permeable membrane down the concentration gradient ( high to low water conc) in response to a solute concentration gradient (water moves from low to high solute gradient)
