Lets Go Pt 2 Flashcards
(28 cards)
Alkanes
Alkenes
Alkynes
Alkaloids
Alkanes: all single bonds
Alkenes: one double bond
Alkynes: one triple bond
Alkaloid: nitrogen containing bases - caffeine, nicotine
Conjugated systems
Aromatic systems
Conjugated systems: more than one double bond separated by single bonds, gives extra stability and can absorb UV-VIS light eg butadiene
Aromatic systems: rings of carbon systems that follow Huckels rule (pi electrons must be even but not a multiple of 4)
Non-covelant interactions
Ionic
- strong bond between ions, governed by electrostatics
Hydrogen
- interaction between partially positive hydrogen atom and partially negative oxygen, nitrogen, sulphur or fluorine atom
- gives water its high boiling point and high cohesive energy
Van der Waals forces
- sum of attractive and repulsive forces between molecules excluding covalent, ionic and non-covalent bonds
Dipole interactions
- attractive or repulsive electrostatic interactions between permanent charges
Induction
- attractive interactions between a permanent multipole and an induced multipole
Dispersion: interactions of instantaneous multipoles
Pi-pi stacking
- attractive interactions between aromatic rings
Hydrophobic and amphiphilic/amphipathic
How glass ionomer cement works
- acrylate in a solution with glass particles
- when solution is mixed that acrylate lowers the pH and glass particles start dissolving
- ions can then bond ironically to eachother and dentine, setting the mixture and binding it to teeth
Four circulatory subsystems and functions
Arterial: carry blood away form heart
Venous: carry blood to heart
Capillary: connect arterial and venous circulatory systems
Pulmonary: movement of blood between heart and lungs
Conditions required for Poiseuille equation
- steady state flow
- fully developed flow
- tube uniformity
Fahraeus - Lindquist effect
For blood vessels with r<1 mm:
- viscosity decreases rapidly at lower radii
- cells cannot get closer to wall than cells radius so concentration differs close to boundary
- more plasma closer to wall
- there can be issues packing cells into vessel
- issues can be reduced through arterial cushioning
Poiseuilles equation (relationships)
- resistance to flow is proportional to 1/r^4
- changes in large artery resistance will have little effect on system but changes in small artery resistance will have large impact on resistance in system
Effects of high shear stress in blood vessels
- damage to RBCs
- damage to endothelium
- platelets activated leading to clot formation
Stenosis: definition and treatment
Stenosis is the narrowing of an artery that results in a significant decreases in blood flow
- angioplasty: balloons made of polymer sheet wrapped around tube is inserted and expanded. This compresses and redistributes the plaque
- stent can prevent reoccurrence; composite structure of balloon and metal wire. Stent is impregnated with drugs to suppress re-formation of deposits
Structure of arterial wall
Tunica intima: fibrous wall, single layer of cells interfaces with blood
Tunica media: elastin aligned around circumference of artery to counteract high hoop stress, collagen randomly oriented to give J shaped curve. Able to resist transmural pressures greater than 10Mpa.
Arteries are pre-stressed.
Tunica adventitia: loose connective tissue and merges with surrounding tissues
Arterial replacement requirements
Mechanical:
- strength to resist hoop stresses, radial elasticity to accommodate pulses, longitudinal flexibility, fatigue resistance
Biological requirements:
- biocompatibility and non-toxicity - innermost layer must not induce clotting or massive cell proliferation
- replacement should be easily visible with X-rays for fitting, and also be accessible and retrievable
Impedance matching:
- if elastic properties differ from surrounding artery, blood can be reflected at boundary introducing resistance - matching elastic modulus can be difficult so thickness of replacement/graft can be altered (as velocity of pulse depends on Eh)
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Development of arterial grafts
Early attempts: solid wall - induced clotting
Porous fabrics: allowed tissue to grow into material, newer variants are crimped to prevent kinking and allow longitudinal expansion
Natural grafts: natural vessels taken from patient and implanted, muscle cells migrate from intima and extend over graft to provide appropriate interface with blood
Cell definition
Conditions cell membranes must meet
A living cell is a self reproducing system of molecules in a container
The membrane must:
- prevent contents escaping but let out waste products
- let in nutrients
- act as a sensor system
- change shape
Lipid bilayer - structure and function
Molecule with hydrophilic tail and hydrophilic head with phosphate group
- will self assemble into bilayers and micelles where the hydrophobic ends point towards each other
- allow through water and non-polar molecules
- form spheres and mend tears
- supported by network of proteins
Hypertonic
Isotonic
Hypotonic
Hypertonic - higher conc. of solute outside of cell > water leaves cell
Isotonic - equilibrium
Hypotonic - higher conc. of solute inside cell > water enters, cell swells and bursts
How plant and animal cell membranes support cell pressures
- plant cells have rigid walls, turgor pressure maintains the shape of plants
- animal cells have protein mesh - insufficient support
- active control of osmotic pressure through ion pumps
How molecules are transported across membranes
- small water soluble molecules are transported by carrier proteins or channel proteins
- macromolecules are transported using vesicles (small sacs of plasma membrane)
The cytoskeleton
Protein filaments that extend through cell interior
- maintain cells shape, helps move cell, acts as pathway for transport of material within cell
- consists of intermediate filaments, Spectrin and actin filaments, and microtubules
- Intermediate filaments: ropes of keratin that distribute effect of local forces
- Spectrin and Actin form mesh that support plasma membrane
Microtubules structure and function
- Pairs of a and B tubulin form 8nm unit
- these assemble into microtubule consisting of 13 protofilaments
- these rapidly assemble and disassemble to provide tracks for vesicles, organelles etc to be moved around cell using motor proteins
- more efficient transport than diffusion
Effect of scale on swimming
Motors on large vs small scales
The Brownian ratchet
- traditional motors rely on temperature gradient (heat engines)
- can’t operate at cell level due to Brownian motion preventing temperature gradient (isothermal)
The Brownian ratchet - random motion that acts on asymmetric series of potential wells
- results in directed motion
How to achieve directed motion in the body
- allosteric proteins can have more than one shape under certain conditions - shapes change by binding to effector molecule at binding site of protein
- therefore protein with number of shapes will move around a rod through Brownian motion - random
- directed motion has lower entropy than random motion
- therefore energy must be put into system to maintain directed motion
- in biological systems this is done through ATP/ADP reaction
The Myosin motor
- F actin forms microfilaments to provide internal scaffolding for mechanical support and cell motion
Movement:
1) Myosin is a molecule with of two identical motor heads. ATP is bound to catalytic core so binds weakly to actin
2) If calcium concentration is high enough the ATP is hydrolysed to ADP and phosphate and one head binds to actin
3) The actin docking causes phosphate release from active site, lever arm swings to ADP bound state so actin filament is moved
4) ADP dissociates and ATP binds to active site - reverts catalytic core to weak binding actin state
Muscle movement - sarcomeres of muscle fibre contract using this mechanism when activated by calcium ions
- heads are arranged in sets that move in opposite directions, causing a contraction
- when calcium concentration falls heads lose contact with filament and muscle relaxed
