Repair and Regeneration Flashcards Preview

Mechanism of Disease > Repair and Regeneration > Flashcards

Flashcards in Repair and Regeneration Deck (38)
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1
Q

What are the two types of healing and define them

A
  • Regeneration: Damaged cells replaced, tissue returns to normal
  • repair: damaged cells cannot be replaced, loss of specialised function by fibrosis & scarring
2
Q

Name the 3 types of cell populations

A
  • Labile
  • Stable (quiescent)
  • Permanent
3
Q

Describe labile cell populations

A
  • High turnover
  • Active stem cell population
  • Excellent regenerative capacity
  • Epithelia
4
Q

Describe the stable cell population

A
  • Low physiological turnover
  • Turnover can massively increase if needed
  • Good regenerative capacity
  • Renal tubules
5
Q

Describe permanent cell populations

A
  • No physiological turnover
  • Long life cells
  • No regenerative capacity
  • Neurons, muscle cells
6
Q

Why are stem cells important?

A
  • Crucial to regeneration

- Destruction can be through radiation & full thickness burns

7
Q

How is regeneration controlled?

A
  • Proliferation of stem cells
  • Covering of defect
  • Contact inhibition
  • Complex contol by frowth factors (cell-cell & cell-matrix interactions)
8
Q

What is organisation?

A
  • Basic pathological process

- Repair of specialised tissue by formation of fibrous scar & granulation tissue

9
Q

What is granulation tissue?

A
  • New capillary loops
  • Phagocytic cells- neutrophils & macrophages
  • (Myo)fibroblasts
10
Q

How are new blood vessels formed?

A
  • Endothelial cell proliferation
  • Buds
  • Canalisation
  • New vessels
11
Q

How are new muscle fibres formed and how does wound contraction occur?

A
  • Proliferation & migration of myofibroblasts
  • Synthesise collagen & ECM
  • Acquire myofibrils & contractile ability
  • Wound contraction
12
Q

What local factors can inhibit healing?

A
  • Infection
  • Haematoma
  • Blood supply
  • Foreign bodies
  • Mechanical stress
13
Q

What systemic factors can inhibit healing?

A
  • Age
  • Drugs (steroids)
  • Anaemia
  • Diabetes
  • Malnutrition
  • Catabolic states
  • Vit C deficiency
  • Trace metal deficiency
14
Q

What is healing by first intention?

A
  • clean, uninfected surgical wound
  • Good haemostasis
  • Edges apposed with sutures/staples
15
Q

What is healing by second intention? When is this type of healing used? What does this lead to?

A

-Wound edges not apposed- healing naturally
-Extensive loss of tissue
-Large haematoma
-Infection
-Foreign body
Leads to: More extensive scarring, more florid granulation tissue reaction

16
Q

Describe fracture healing

A
  • Haematoma is organised
  • Removal of necrotic fragments
  • Osteoblasts lay down woven bone
  • Remodelling according to mechanical stress
  • Replacement by lamellar bone
17
Q

How can non-union of fractures occur?

A
  • Movement
  • Misalignment
  • Infection
  • Interposed soft tissue
  • Pre-existing bone pathology
18
Q

How does healing in the brain occur?

A

-Neurons are terminally differentiated
-Supporting tissue is glial cells rather than collagen
-Hence damaged tissue is removed leaving a cyst
-Gliosis rather than scarring
-

19
Q

What are Koch’s postulates?

A
  • Causative organism must be isolated from every individual suffering from the disease
  • Causative organism must be cultivated artificially in pure culture
  • Causative organism is inoculated from pure culture, the typical symptoms of the infection must result
  • Causative organism must be recoverable from individuals who are infected experimentally
20
Q

What is Koch’s postulates for genes?

A
  • Genes encode virulence factors
  • Gene encoding the trait should be present & transcribed in a virulent strain
  • Gene encoding the trait should not be present or should be silent in a strain that does not cause disease
  • Disruption of the gene in a virulent strain should result in the formation of a strain that is incapable of causing disease
  • Intro of the gene that did not previously cause the disease shuld transform the strain into one that does cause disease
  • The gene must be expressed during infection
  • Antibodies raised against the gene product or appropriate cell-mediated immunity should protect experimental subjects against disease
21
Q

What are problems with Koch’s postulates?

A
  • Difficulty of isolation the causative agent
  • Impossible to grow some pathogens in artificial culture (leprosy)
  • Ethical objections
  • Animal models not sufficient
22
Q

Describe the structure of viruses

A
  • Nucleic acid core wrapped in a protein coat made up of capsomeres
  • DNA or RNA
  • Some have an envelope
23
Q

Give examples of disease causing viruses

A
  • Herpes simplex virus
  • Respiratory syncytial virus (infects only cells of the resp tract)
  • Adenovirus
24
Q

What are bacteriophage

A

-Class of viruses that attack bacteria

25
Q

What shapes can viruses take?

A
  • rod-shaped
  • round
  • brick-shaped
  • bullet-shaped
  • icosahedral
26
Q

Describe microfungi

A
  • Fungi are eukaryotic
  • Most possess a cell wall of chitin
  • Moulds = fungi that grow in mats of tiny filaments= hyphae
  • Form mats= Mycelia
  • May or may not subdivide into separate compartments=Septa
27
Q

Describe Protists

A
  • Unicellular eukaryocytes

- 4 classes= Apicomplxa, Flagellate Protista, Ciliate Protista, Amoebae

28
Q

What infections are caused by protists

A
  • Malaria
  • Amoebic meningitits
  • Amoebic dysentry
  • Diarrhoea
29
Q

What can Trichomonas Vaginalis cause?

A
  • Vaginal infections
  • Causes foul-smelling vaginal discharge
  • Men asymptomatic carriers protists can cause balantitis in men
30
Q

What are the most common shaped bacteria?

A
  • Cocci= round

- Bacilli= rod-shaped

31
Q

Describe the outer membrane of Gram negative bacteria

A
  • outer leaflet containing lipopolysaccharide
  • Sugars form surface antigen
  • Lipid A acts as endotoxin responsible for symptoms
32
Q

What can help a bacteria stick to surfaces?

A

Produce slime (strep mutans) such as surface of teeth forming plaque and leading to dental caries or strains of staphylococci living on skin help them to stick to plastics- infections associated with implanted medical devices

33
Q

What highly resistant structures can be produced by some bacteria?

A
  • Endospores
  • Resist a range of hazardous environments
  • Protect against hear, radiation, desiccation
34
Q

Which infections can be spread through drinking water?

A
Water contaminated with human faeces
-Typhoid
Cholera
-Hep A
-Dysentry
-Poliomyelitits
35
Q

What are fomites?

A

Inanimate objects which act as vectors of infection

36
Q

What are intoxication illnesses? (NOT DRINKING)

A
  • Tetanus & botulism/ergotism
  • Victim only needs to be exposed to toxin not live microorganism
  • Tetanus= lock jaw as muscles go into rigid spasm (risus sardonicus)
37
Q

What are virulence factors?

A

Traits used to complete the cycle of infection

38
Q

What are the mechanisms by which bacteria cause disease?

A

-Production of toxins (endo/exotoxins)
-Exploiting production of structures that enable microorganisms to attach to surfaces
-Production of aggressins
Initiating undesirable consequences of host defences