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Flashcards in Unit 3 Deck (44)
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1
Q

What are 2 techniques that measure thermal properties of polymers?

A
  1. Differential Scanning Calorimetry (DSC) 2. thermal gravimetric analysis (TGA)
2
Q

Describe one technique that measures thermal properties of polymers.

A

DSC: differential scanning calorimetry. 2 Compartments are used, one has a sample, one is a reference. Compartments are heated and sample undergoes transition, enthalpy changes. Varying electrical energy must flow into sample pan in order to keep the 2 pans at the same temperature. On the heat flow v. temperature plot, a peak denotes more heat required in the reference pan and sample undergoes endothermic phase transition (sample absorbing heat). Tc (crystallization temperature) is found by measuring area within inflexion peak. On the plot, a dip denotes less heat requred in reference pan and sample undergoes exothermic transition(releasing heat). The area found under the point is the Tm (melting temperature)

3
Q

State 3 advantages of SIMS over XPS

A

SIMS: secondary ion mass spectroscopyXPS: x-ray photoelectron spectroscopy. SIMS has higher sensitivity than XPS, more sensitive to top surface of material than XPS, applicable to any solid.

4
Q

What principle is thermogravimetry analysis based on?

A

examines process of weight changes as function of time, temperature, and other environment conditions. can obtain material composition and stability information.

5
Q

What is gel permeation chromatography?

A

a technique for structural and organic analysis. It determines molecular weight distrubution of a polymer by comparing speeds of small and large polymer molecules. There is a compartment with columns filled with gel beads and spaces between columns. The polymer sample is diluted then placed in compartment. larger molecules elute more quickly because they travel through spaces while small polymers molecules travel through all gel pores.

6
Q

What is contact angle measurement?

A

The angle between the surface and a line that is tangent to a drop of liquid on the surface. 90= hydrophobic, >90=hydropgobic, <90 = hydrophilic

7
Q

What is atomic force microscopy?

A

an image analysis technique. a member of scanning probe microscopy “family.”

8
Q

How does atomic force microscopy work?

A

shows intermolecular interaction between small atomic probe and molecules on surface. uses probe across surface, deviations characterize material surface. a 3D model can be produces.

9
Q

What are the modes of probe contact for scanning probe microscopy?

A

Contact: characterizes by dragging probe continuously across surface

Non-contact: characterizes by forces such as van der walls and runs just above the surface.

Tapping: minimizes contact and damage, intermittant contact,

10
Q

When the contact angle is below 90 degrees, what is hydrophobicity?

A

Hydrophilic

11
Q

What are advantages and disadvantages to an in vivo experiment?

A

Advantages: Better approximation to human body environment

Disadvantages: demanding protocols by Animal Welfare act, must have an animal that has a c​omparative model to human body environment

12
Q

Name 2 techniques for surface analysis.

A

Contact Angle measurement, X-ray photoelectron spectroscopy

13
Q

Describe information obtained by contact angle measurement

A

Qualifies hydrophobicity of surface

14
Q

Describe information obtained by XPS

A

X-ray Photoelectron Spectroscopy

Provides information about elemental composition. A series of element specific peaks are created which correspond to binding energies of photoelectrons. Elemental composition of surface can be quantified by measuring area under the peaks.

The X-ray excited the surface electrons, if their binding energy < x-ray energy, the electrons will be emitted from the parent atom as a photoelectron.

This qualifies as only surface analysis bc the x-ray can only excite photoelectrons on the outer surface of the material , these ezcaped electrons can be measured

15
Q

State 2 techniques for image analysis and describe information obtained by each of these techniques.

A
  1. Atomic Force Microscopy: a scanning electron probe test that characterizes surface by use of probe straveling across and can create 3D models based on info obtained.
  2. Scanning Electron Microscopy: provide image of sample with high resolution and high depth of field. Image is created by scanning a sample with high energy beam of electrons. The electrons and their interaction with the surface produce the image
16
Q

What is GPC and what information does this technique provide?

A

Gel Permeation Chromatography

Determines molecular weight distribution of a polymer. (structural and organic analysis)

Quantifies larger v. smaller polymer molecules in a polymer.

A sample is diluted and passed through a compartment with colums containing gel beads. Small molecules pass through pores of columns while large molecules pass through space between columns. Larger chains elute the sample more quickly and these results are quantified by UV or light detectors.

Plot is concentration agaist elution volume.

17
Q

What is XRD and what information does this technique provide? How is data interpreted?

A

X-Ray Diffraction

  1. Uses x-rays to determine crystal structure.
  2. Planar spacing value of unit cell in crystalline structure is obtained by shooting an x-ray beam into a sample at an angle
  3. then measuring the intensity of reflected (outgoing) rays and diffraction angle of outgoing rays.
  4. The distance between planes can be computed with this info
  5. Distances could also be obtained by calculating area under peaks of the intensity v. diffraction angle graph.

**Crystalline structure spacing values can be matched to atoms since the have already been characterized. **

18
Q

What is the function to mitochondria?

A

Production of ATP

19
Q

What is the ECM? What are it’s components?

A

Extracellular matrix.

A dense region in which cells are suspended. Connects cells in tissues.

20
Q

Describe 2 types of cell contacts.

A
  1. Cell-cell contact: cells communicate directly
  • Tight junction
  • gap junction
  • desmosome
  1. Cell-ECM contact: Cells communicate indirectly
  • hemi-desmosome
  • focal adhesions
21
Q

What are the cell adaptive responses?

A
  1. Hypertrophy: growth in cell size without number increase
  2. Hyperplasia: increase in cell number
  3. Atrophy: decrease in cell size without number increase
  4. Metaplasia: cell transformation from one mature cell to another
22
Q

What are 2 cell receptors

A
  • Selectins: recognition receptors of specific carbohydrate groups present on target cell membrane.
    • heterophilic binding (reacts with a different kind of adhesion molecule)
  • Mucins: protein based molecules that contain covalent bonded carbohydrates. They present ligands for binding to selectins
    • heterophilic binding
23
Q

Name 5 components of ECM

A
  1. Collagen
  2. elastin
  3. proteoglycan
  4. glycoprotein
  5. other ECM components
24
Q

Explain the difference between tight junctions, gap junctions and desmosomes

A

Tight Junction: adjacent cell membranes adhere to each other and prevent even small molecules from passing between cells.

Gap Junction: small hydrophilic channels created by a plaque like structure that connects 2 different cell membranes.

Desmosome: mechanical attachment of 2 cells; belt or spot

25
Q

What are the 2 types of cell death?

A

Apopotosis: Cell suicide mechanism. Triggered by metazoans which control cell number and eliminate threatening cells

Necrosis: Localized death of living cells bc of infection or interruption of blood supply

26
Q

State 4 soluble factor cell signaling methods

A
  1. Contact dependent
  2. paracrine/autocrine

C. synaptic

D. endocrine

27
Q

Name 3 structures inside the cell

A

Mitochondria, golgi apparatus, nucleus, ribosome

28
Q

What are gap junctions?

A

A type of cell-cell connection that connects membranes by creating hydrophilic channels through intermittent plaque structures

29
Q

State and describe the steps involved in tissue processing. (5)

A
  1. Obtain tissue specimen through biopsy, excision, or resection
  2. Fix speciment to prevent from decay (foramalin, glutaraldehyde, or none because it is frozen).
  3. embed spcimen in usable form such as ice epoxy resin or paraffin
  4. Section specimen for easy identification and decrease chance of loss/contamination
  5. stain specimen for contract in order to increase visibility with light or electron microscopy
30
Q

State and describe 2 factors that affect protein adsorption

A

Structural rearangements in protein.

Dehydration of sorbent surface and part of protein surface

31
Q

What is the sequence of host reaction following implantation of medical devices?

A
  1. injury
  2. blood-material interaction
  3. provisional matrix formation
  4. acute inflammation
  5. chronic inflammation
  6. granulation tissue formation
  7. foreign body reaction
  8. fibrous capsule development

“the ILL Bear Presents with Acute on** Chronic** Grizzly Foot Fungus”

32
Q

What is resolution?

A

A steady state condition at site of implant since presence of implant prevents attainment of original condition.

33
Q

What is the objective of blood clotting?

A

Serves as a provisional matrix for further healing and stops excessive bleeding

34
Q

What is the difference between immunity and allergy?

A

Immunity: property of being secure or nonsusceptible to the adverse effects of foreign agents

Allergy: property of being especially sensitive or hypersensitive to foreign agents.

35
Q

Name 3 cells that actively take part in the sequence of locat events following implantation

A

Monocytes, granulocytes, Fibroblasts

36
Q

What are granulocytes?

A

Granulocytes are any blood cell containing specific granules

37
Q

Give 2 characteristics of platelets

A
  • Platelets release growth factors (like FBF, fibroblast growth) in order to promote tissue healing.
  • Platelets are flat disks
38
Q

What is a leukocyte?

A

White blood cell capable of ameboid movement

39
Q

What does the fibrinolytic system do?

A

Removes unwanted fibrin deposits to improve blood flow and facilitate healing process.

40
Q

What is the body’s response to damaged blood vessels?

A

Cells migrate to wound and form a fibrin clots which serves as a provisional matrix. leking vessels are constricted and platelets are trapped in matrix to build a clot to heal damage. Platelets release growth hormone for tissue growth to promote healing.

41
Q

What is tumorigenesis?

A

New Growth: process of excessive and uncontrolled cell proliferation

42
Q

Differentiate between cell mediated and hymoral immune response mechanisms

A

A. Humoral: in the humor fluid. Production of freely circulating antibodies formed by B-lymphocytes

B. Cell Mediated: T-cells recognize and kill intracellular infection, cancer of FB

43
Q

State 2 drawbacks of antibiotic impregnated implants

A
  1. Chronic use of antibiotics leads to resistant virulent strains.
  2. Appropriate antibiotic may not be used.
44
Q

Differentiate between benign and malignant tumors.

A

Benign: Do not invade adjacent tissue or metastasize.

Malignant: invade adjacent tissue and metastasize via blood and lymph