LECTURE QUESTIONS 1-15 Flashcards
Intermolecular forces and bonds in liquids.
intermolercular forces: Van der waals type (1/r^7) between electric dipoles, they are weak forces between electric dipoles. Dipole-Dipole interactions and london dispersion force
hydrogen bonds are stronger and they form when a hydrogen atom is covalently bonded to a highly electronegative atom
Bonds: Simple (only van der waals links) and complex (hydrogen bonds)
Phenomena at the level of interfaces
interfacial phenomenas are behaviors that occur at these interfaces.
An interface is a boundary or a surface between different materials or phases that are occupied by different matter, or by matter in different physical states.
The store of energy is directly proportional to its area.
The role of superficial phenomena at the level of the pulmonary alveoli. Pulmonary surfactant
Pulmonary surfactant: is a complex mixture of lipids and proteins that is produced by specialized cells in the lungs (type ll alveolar cells) and this surfactant plays a crucial role in maintaining the function of the respiratory system, partially in the alveoli
the walls of alveolis are lined with a thin layer of surfactant and the surface tension of this fluid would cause them to collapse, making it difficult for them to inflate during breathing
alveoli can be compared to gas in water, as the alveoli are wet and surround a central air space. The surface tension acts at the air-water interface and tends to make the bubble smaller (by decreasing the surface are of the interface) The gas pressure (P)n needs to keep equilibrium between the collapsing force of surface tension (y) and the expanding force of gas in an alveoulus of radius (r ) is expressed by the law of laplace: ⃤⃤⃤ p(difference of pressure)=2/r
The molecular structure of solid water and liquid water. Hydrogen bonding
Liquid water:
in the liquid state, water molecules are in constant motion
the hydrogen bonds are continually breaking and reforming as water molecules move
the lattice (structure) is partially destroyed
even in liquid state, water molecules maintain a degree of organization due to the hydrogen bondings
Solid water
in a solid state, water molecules form a hexagonal lattice structure
each oxygen atom is bonded to four hydrogen atoms and two of these hydrogen bonds are covalently bonded into the central oxygen atom
the hydrogen bonding is relatively stable and creates an open framework, resulting in lower density compared to liquid water. Thats why ice floats on water
Hydrogen bonding is a type of interaction between molecules where a hydrogen atom in one molecule is attracted to a highly electronegative atom like (nitrogen or oxygen) in another molecule and it creates a dipole-dipole attraction between two molecules
The physical properties of water. Structure models of water in liquid state.
Water has a high specific heat and because of this it can absorb large amounts of heat energy before it begins to get hot.
High heat of vaporization, which means that it requires a substantial amount of energy to transition from a liquid to gas
high surface tension, which allows small objects to “flow” on water
Structure models of water in liquid state
H2O molecules attract each other through the special type of dipole-dipole interaction known as hydrogen bonding and in liquid state each water molecule links to four others creating a tetrahedral arrangement and they are able to move freely and slide past each other
Molecular structure of aqueous solutions
An aqueous solution is a solution in which the solvent is the water itself. it is mostly shown in chemical equations by appending (aq) to the relevant chemical formula. for example, a solution of table salt or sodium chloride (NACl), in water would be presented as NACI(aq)
The word “aquous” which comes from aqua means pertaining to, related to, similar to or dissolved in water. as water is great solvent and is also naturally abundant
Physical techniques for the study of water in biological systems
destructive techniques: (methods that damage the sample during the process)
freezing techniques: used for determining the freezing point
dehydration techniques: water compartmentalization
Non-destructive techniques: (methods that dont cause any permanent damage)
IR spectrophotomery: studies the vibrational modes
Calorimentric: measures the amount of thermal energy being transferred
Dielectric relaxation:
MRI
Deuterization
Definition and classification of dispersed systems. Molecular solutions. Suspensions. Emulsions
A disperse system is a two-part system made up of microscopic particles and the medium in which they are suspended. usually a mixture of two or more substances.
dispersnat
dispersed
An example of a disperse system is a foam such as shaving cream. gels, emulsions and solid foams
Dissolution of gases in blood and tissues. Henry’s Law
Henry’s law states that the amount of gas that dissolves in a liquid is directly proportional to the partial pressure of the gas above the liquid. This law explains why gasses with high solubility will have a higher concentration in the blood than the less soluble gases.
Hyperbarism: Under high pressure, gases dissolve more in the blood and tissues. there are fast and slow tissues
Disparism: pressure differences between different tissues, leading to conditions like gas embolism
Hyperoxia (p>1.7atm): is a state of excess supply of oxygen in blood and tissues and too much oxygen can lead to CNS toxicity. similar symptoms to the beginning stages of general anaesthesia.
Colligative properties of solutions.
lower saturated vapor pressure -pressure which is exerted by a vapor(steam) when liquid water is heated and it turns into water vapor, which is the gaseous form of water
lower freeze point - temperature at which a liquid became a solid
increase of boiling point
osmotic pressure - pressure which is exerted by a solvent to move molecules of a solute from an lower solute concentration to higher solute concentration and the movement of the solvent creates a pressure and this pressure is the osmotic pressure.
Electrical properties of solutions
degree of dissociation - is a fraction of original solute molecules that have dissociated =nN
conductivity of an electrolyte solution is a measure of its ability to conduct electricity. X=1
activity coefficient is a factor used in thermodynamics to take into account f
deviations from ideal behaviour in a mixture of chemicals
Activity a=fc
ionic strength is a measure of the concentration of ions in a solution
Ionic potentials. Nernst’s law.
Ionic potential: Is the ratio of electric charge to the radius of an ion
Nernst law, also known as nernst equation, is a formula that relates the voltage of an electrochemical cell to the concentrations of its reactans and products.
E=E∘−RTnFIn(Q)
Classification of transmembrane potentials. Local potentials. All or nothing potential.
The transmembrane potential refers to the voltage differences across the cell’s plasma membrane. There are different classifications of transmembrane potentials, including local potentials and all or nothin potentials
Local potentials: are changes in transmembrane potential that occur in a specific region of the cell membrane and these changes can be depolarizing (making them less negative) and hyperpolarizing (making them more positive). they are usually caused by the opening of the ion channels in response by a stimulus
All or nothing potentials or action potential: Are rapid, brief changes in the transmembrane potential that propagate along the entire length of the cell membrane. Unlike local potentials, action potentials are all in or nothin potentials, which means that they occur completely or not at all.
They are triggered when a local potential reaches a certain threshold. once the threshold is reached, voltage-gated ion channels open, allowing a rapid influx of sodium ions causing depolarization and this is followed by the opening of potassium ions which then leads to repolarization and the inside of the cell becomes positive
Neural synapses. Prime membrane transport inhibitors.
Neural synapses: are specialized junctions between neurons that allow for the transmission of the signals, known as neurotransmission and they realize the contact between two neurons or between a neuron and a muscle or glandular cell
Synapses can be Chemical or Electrical
Chemical synapses: they are directly connected by gap junctions and then ions pass directly from one neuron to another. They are very fast transmission and are found for example in certain parts of the brain and the heart because they require the possibly fastest response ; Quick and direct communication
Electrical synapses: they are neurons that are not directly connected and there is a small gap in between them (synaptic cleft) and the chemical messengers (neutrotransmitters) carry signals across the gap, it’s a slightly slower transmission due to the extra step. They are most common in the nervous system ; Allows for more complex communication and modulation
Transport inhibitors are substances that interfere with the movements of ions, molecules or neurotransmitters. They can block specific channels or proteins and prevent the chemical message from being passed along. For example some drugs that block nerve signals, like GABA drugs which are calming and many medicines used in the treatment of epilepsy have an impact on nerve signals and have many more side effects
Calculation of the resting potential. Goldman-Hodgkin-Katz equation.
The resting potential is electrical charge difference across the membrane of a non-active (resting) cell, simply it’s like the baseline electrical state of a cell when it’s not sending any signals or actively doing something.
and its calculated by the Goldman-hodgkin-katz shortly GHK equation and its calculated by this formula:
