Biophysics Summarised Notes.docx

Thermodynamics

Concerned with heat, temperature, energy, and work relationships.

Thermodynamic Systems

Isolated (no exchange), Closed (no matter exchange, heat/work exchange), Open (matter and energy exchange).

Thermodynamic State

Described by variable composition.

First Law of Thermodynamics

Energy transformation, dE= Q-W, Q=heat, W=work.

Entropy

Measure of disorder, chaos increase leads to higher entropy.

Free Energy

Convertible energy in a system.

Second Law of Thermodynamics

Isolated system entropy never decreases.

Biothermodynamics

Open systems, non-equilibrium, stationary systems.

Biological Membrane

Dynamic structure of lipids and proteins.

Passive Membrane Transport

Movement from high to low concentration without ATP.

Ionophores

Lipid-soluble peptides aiding ion passage.

Ion Channels

Proteins allowing ion passage across membranes.

Active Membrane Transport

Movement with ATP assistance.

Electric Membrane Potential

Difference in electrical potential across a cell.

Equilibrium Potential

Net ion flow zero due to equal forces.

Resting Potential

Stable membrane polarity equilibrium.

Action Potential

Membrane potential change due to stimuli.

Ion Theory of Excitation

Ion current based on membrane conductance and potential.

Action Potential Propagation

AP spread through local currents.

Electrotonic Potential

Local non-propagated potential.

Cable Model

Used to calculate AP propagation time.

Blockage of AP Spreading

Interruption of AP propagation.

Bioelectric activity

The electrical conductivity and impulses in living organisms based on charged ions such as Na+, K+, Cl-, and Ca2+.

Smooth Muscle

Networks of contractile fibers (actin and myosin) bounded by dense bodies, capable of phasic or tonic contractions.

Skeletal Muscle

Cylinder-shaped cells organized in parallel forming muscle fibers with actin and myosin filaments in sacromeres for contraction.

Contractile Mechanisms

The process of muscle contraction regulated by the CNS through motor neurons and electro-mechanical coupling involving ACh, Ca2+, and ATP.

Cardiac Muscles

Myogenic cells capable of contracting without nervous stimulation, with the sarcomere as the contractile unit and the sinus node as the source of initial action potential.

Intercellular Communications

Involving electrical and chemical information systems, including neuronal transmission and chemical signaling through neurotransmitters and hormones.

Receptors

Complex proteins integrated into the membrane that identify, bind ligands, and transmit signals, categorized into channel-linked, enzyme-linked, G-protein coupled, and intracellular receptors.

Electrokinetic Phenomena

Effects in fluids or porous bodies related to zeta potential, indicating the stability of colloidal dispersion based on repulsion between charged particles.