11) Infection And Inflammation Flashcards

Question

What is an example of hypertrophy and hyperplasia occurring together

Answer 1

Uterine enlargement during pregnancy is a consequence of smooth muscle hypertrophy and hyperplasia

Answer 2

Shrinkage in cell size due to loss of cell substance Functionally diminished but alive eg immobilised or aging limb muscle

Answer 3

Reduction in number of functioning cells due to reduction in functional demand (myometrium of uterus postpartum) - usually by programmed cell death (apoptosis)

Answer 4

Change in type of cell - reprogramming of stem cells Survival mechanism in response to injury ef smoking - specialised function is lost. Can predispose to neoplasia

Answer 5

Protective mechanism that functions to: 1) eradicate cause of injury 2) remove damaged cellular material 3) initiates repair process

Answer 6

1) vasodilation - slowing local blood flow to the area - allowing time for plasma containing mediators to leave and for neutrophils to come into contact with the vessel wall - enabling cells to contact the capillary endothelium - generating heat and redness 2) increased vascular permeability - allowing plasma carrying mediators out - causing swelling (oedema / tumour/ turgor) 3) cellular activation and migration - neutrophils are activated to migrate from the vessels. They have great capacity for phagocytosis - short lived so need to be replaced

Answer 7

1) resolution - rare 2) repair (fibrosis / scarring) 3) chronic inflammation - lasts as long as stimulus lasts 4) abscess formation - neutrophils doing a lot of phagocytosis, they die and produce pus so body produces collagen- heals by fibrosis

Answer 8

Restitution of normal tissue structure and function -fluid is reabsorbed. Neutrophils and macrophages clear damaged tissue Growth factors and cytokines are released into damaged area to help regenerate

Answer 9

Cells divide to replace themselves and to expand and differentiate into mature tissue Skin epithelium is generated by the basal layer undergoing cell division to give rise to the laters above. These become progressively more differentiated and eventually die and are shed (this is called turnover)

Answer 10

Labile- replicates throughout life Stable- non dividing in normal circumstances but capable of regeneration Permanent - non dividing cells

Answer 11

*Severity of tissue damage: parenchyma (functional cells) or parenchyma and stroma (support cells / connective tissue) Labile- can resolve Stable- capable of regeneration so can resolve or scar Permanent - non dividing cells; always scarring * type of agent which has caused damage eg TB, virus) * complete resolution is uncommon

Answer 12

1) granulation tissue - macrophages, fibroblasts and new blood vessels 2) fibrosis and scar formation - fibroblasts lay down matrix - scar is formed as amount of collagen laid down is increased to strengthen the tissue 3) remodelling - over time the number of vessels is reduces and a pale scar remains

Answer 13

- granulation tissue - building tissue to fill the wound - fibroblasts secrete: matrix components, growth factors to stimulate angiogenesis - epithelial cells re grow over the wound

Answer 14

- remodelling / organisation of the matrix to develop appropriate tissue architecture for the function of the tissue. Due to the action of fibroblasts laying down collagen and collagenases breaking down collagen to orientate for maximal tensile strength - wound contraction - decreased vascularity

Answer 15

Resolution: - arises from damage to parenchyma in labile / stable tissues - remove damaging stimulus, inflammatory cells, mediators and exudate - replace injured cells by regeneration - restore normal function - Minimal / absent evidence of damage Repair: - arises from damage to parenchyma and stroma - replace damaged tissue with connective tissue - formation of granulation tissue - formation of scar tissue - remodel for strength - lacks functional capabilities of damaged tissue

Answer 16

Growth factors are hormone like molecules that stimulate proliferation, differentiation and maturation of cells. In healing they attract endothelial cells and fibroblasts and therefore have a role in angiogenesis and production of the extracellular matrix

Answer 17

- antibody: blocks binding and entry to cells, activates intra-cellular degradation via TRIM21 - antibody + complement : damage to enveloped viruses, opsonisation for phagocytosis - antibody bound to infected cells: antibody-dependent cellular cytotoxicity

Answer 18

Glycoproteins are synthesised by mRNA and inserted into the the host plasma membrane - matrix proteins synthesised by viral mRNA will form part of the envelope. - modified region of host plasma membrane extends out from cell surface - modified region is pinched off from host cell, enclosing viral matrix protein and RNA within capsid; modified membrane and matrix from viral envelope

Answer 19

1) antibodies to virus surface antigens may block the binding of viruses to cell surface receptors, neutralising the viruses. 2) antibodies can activate complement that may damage the lipid membranes of enveloped viruses 3) antibodies and complement proteins may also act as opsonins to promote phagocytosis of viruses 4) some viruses have evolved evasion mechanisms to protect themselves from the immune system eg influenza mutates the structure of its surface proteins

Answer 20

Antigenic drift is gradual changes in the virus due to accumulation of point mutations. Antigenic shift is the dramatic changes due to recombination between different strains of the virus

Answer 21

1) early innate response by interferons and natural killer cells limits the growth and spread of infection 2) adaptive response by Tc cells takes longer to activate but has higher efficiency 3) infected cells produce and secrete type 1 interferons. These bind to receptors on neighbouring cells and trigger an anti-viral state in which these cells are resistant to virus replication 4) type 1 interferons enhance expression of HLA class I making cells better targets for Tc cells and activate natural killer cells 5) NK cells sense changes in the infected cells’ surface constituents that are indicative of the cells being abnormal

Answer 22

- small (20-50nm) - too small to see down light microscope (can be seen down electron microscope) - filterable agents

Answer 23

Simple | Contain nucleic acids surrounded by proteins and there is an outer membrane of lipid

Answer 24

Metabolically inert - rely on host cell - obligate intracellular parasites

Answer 25

Independent synthesis of component parts - may be in separate parts of the cell under separate control - subsequent assembly into new particles

Answer 26

DNA: - double stranded or single stranded - circular (covalently closed) or linear - 3kb-200kb (kilo bases)- 1 protein is about 1000 ``` RNA: - ds or ss - ss may be +ve or -ve polarity - linear or segmented (influenza- 8 strands of -ve mRNA) 5kb-10kb ```

Answer 27

Capsid formation : - symmetry -icosahedral (sphere) or helical Attachment: - specific interaction between viral ligand and cellular receptor - determines viral tropism Enzymes: - mostly concerned with macromolecular synthesis Interference with cell function - to stop apoptosis, to avoid immune recognition

Answer 28

Derived from host cell membranes Must contain external attachment proteins Stripping of envelope leads to loss of infect II the (lots of things strip lipid: alcohol, aldehyde) - enveloped viruses generally more fragile (easy to strip lipid and disinfect)

Answer 29

1) attachment : viral ligand / cellular receptor 2) entry : - endocytosis - fusion : viruses that have a lipid envelope - fuses with cell surface lipid 3) uncoating : 4) macromolecular synthesis : - multiple copies of viral genome - multiple copies of viral proteins (requires production of +ve ss RNA ie mRNA 5) assembly 6) release : - budding (yields enveloped virus) - cell lysis.

Answer 30

Because it can then be integrated into the host cells chromosomes using DNA integrase

Answer 31

Total genetic material of an organism, comprising the genes contained in its chromosomes

Answer 32

Hyperplasia that occurs in a non-uniform pattern in an organ or tissue includes hyperplasia of the prostate gland and breast

Answer 33

Reduction in the volume of a tissue (reduction in volume or cell number) - cell loss is commonly replaced by adipose tissue or fibrous tissue

Answer 34

``` Denervation Immobilisation Reduced endocrine stimulation Ischaemia Ageing ```

Answer 35

Most instances of involution are the result of withdrawal of an endocrine stimulus Eg - breast after cessation of lactation - uterus after parturition - thymus after puberty

Answer 36

Hypoplasia: incomplete growth of an organ Agenesis: complete failure of development of an organ in embryogenesis

Answer 37

Oesophagus in response to reflux - squamous epithelium to columnar Lungs in response to smoking - columnar epithelium to squamous Bladder in response to stones - transitional epithelium to squamous

Answer 38

Cells exposed to pathological stimuli may become damaged - molecular responses aim to repair damage and may manifest in structural changed - these changes are called cellular degenerations - these degenerations are potentially recoverable

Answer 39

In a damaged cell, mechanisms which maintain ion pumps fail. Water is retained by the cell Membrane systems become dilated with fluid (forms sac like structures- vacuoles) Cell becomes vacuolated and (histologically) pale stained

Answer 40

A large space within a cell filled with a substance eg mucin or glycogen - a cell is said to show vacuolation when it has developed vacuoles.

Answer 41

A cell which is severely vacuolated as a result of pathological fluid accumulation is said to have undergone hydropic degeneration

Answer 42

- if a damaging stimulus abates, a cell may recover - damaged organelles are removed by autophagy - damaged proteins are removed by ubiquitin-mediated proteolysis - residual materials may remain as inclusion bodies - stigmata of damage

Answer 43

If cellular damage is severe or maintained it may lead to cell death - may occur in the form of tissue necrosis - may also occur as apoptosis in which it is programmed and managed

Answer 44

Some stimuli to cells cause instant protein coagulation - cells die immediately - stimuli: extreme heat, extreme pH change, sudden anoxia

Answer 45

If cell damage is above a level that is capable of recovery the cell dies - cell death is followed by a series of structural changes called necrosis - liquefactive necrosis is the most common form of necrosis - cell death is accompanied by spillage of cellular contents into the environment

Answer 46

Necrosis liberates cell proteins into tissue fluids This stimulates a tissue response to injury The tissue response to injury recruits neutrophils and other cells in a process called inflammation

Answer 47

Pathogens that only cause serious disease when host defences are impaired

Answer 48

Capable of causing disease in absence of immune or physiological defect

Answer 49

Contribute to the ability of both groups of bacteria to cause disease. Rarely is possession of a single virulence determinant sufficient to make a bacterium pathogenic

Answer 50

1) colonisation- establishing the disease in the tissues (adhesion and nutrient acquisition) 2) invasion of tissues - move from initial site of infection deeper into tissues or from site to site 3) avoidance of host defences 4) tissue damage 5) transmission- from one host to another

Answer 51

Establishment of a stable population of bacteria in the host Source of bacteria is in the environment, infected individuals or our own normal flora Frequently the first interaction occurs on a mucosal surface eg respiratory tract, GI tract or urogenital tract

Answer 52

Mucus forms a protective barrier and these sites are also subject to normal physiological flushing mechanisms eg saliva in the mouth and peristalsis in the gut. To overcome these flushing mechanisms and persist, bacteria must adhere to mucosal surfaces

Answer 53

1st stage- association- involves non specific forces eg charge and hydrophobicity - weak and reversible 2nd stage- adhesion- involves specific binding between bacterial adhesins and host receptors (strong interactions and non-reversible) Subsequent stages may result in aggregation to produce a biofilm on a surface

Answer 54

Fimbriae/ pili- rod like protein adhesins eg E. coli Polysaccharide adhesins eg oral streptococci

Answer 55

Iron is essential for bacterial growth In tissues, free iron levels are below that required to support bacterial growth To acquire enough iron to grow, bacteria express high affinity iron uptake systems 2 main systems: 1) siderophores 2) direct binding of iron transport proteins

Answer 56

Complement alone kills many gram-negative bacteria Complement and antibodies oposonize bacteria, promoting phagocytosis and killing by polymorphonuclear leukocytes and macrophages Cytokines modulate both antibody and phagocytic responses

Answer 57

Gram negative bacteria causing sepsis are complement resistant so can survive and grow in bloodstream. Their resistance is due to lipopolysaccharide on bacterial surface. Polysaccharide side chains of LPS sterically hinder access of activated complement components to the bacterial membrane Capsules may also interfere with complement binding Surface proteins inhibit binding of complement to the bacterial surface Staphyloccous aureus produces factors that interfere with complement activation

Answer 58

Some bacteria produce toxins which kill phagocytes or inhibit their migration to sites of infection Inherent physical properties of some bacterial capsules inhibit phagocytosis Some bacteria inhibit the pathways involved in intracellular killing within phagocytes

Answer 59

- acts centrally to elicit pyrogenic response. Evidence for specific cytokines receptors in hypothalamus - elevates corticosteroids as part of ‘stress response’ which promotes inflammatory in the short term Increases hepatic protein (heat shock or acute phase proteins eg lipopolysaccharide binding protein) This stimulates bone marrow to release leukocytes

Answer 60

Granulation of the tissue - dense population of macrophages, fibroblasts and neovascularisation in a loose matrix of collagen - fibroblast produce collagen for structural purposes - proliferation of blood vessels ensures supply of nutrients and oxygen - various metalloproteinases stimulate cell movement in wound area

Answer 61

Granulomatous condition eg rheumatoid arthritis or scleroderma

Answer 62

The formation of new blood vessels which occurs during wound healing and is promoted by growth factors This process is also seen in many malignant tumours and has become a target for anti-cancer therapy

Answer 63

Both don’t produce much oestrogen and testosterone and DHEA levels decline with age

Answer 64

High oestrogen = faster wound healing | High testosterone = slower wound healing

Answer 65

Cessation of proliferative phase leads to maturation phase and remodelling of the tissue. 1) reduced vascularisation : lessens demand for nutrients as metabolic activity of tissue declines 2) remodelling of collagen and reinnervation of nerves - increases strength of tissues and the return of ‘sensation’ but lack of elastin causes scar tissue

Answer 66

Long term treatment inhibits inflammation at several steps in the process by reducing, among others: 1) prostanoid and leukotriene production and therefore inflammatory synergy between humoral and cellular factors 2) expression of cell adhesion molecules 3) chemotaxis of neutrophils 4) cytokines production 5) potentiates vasoconstrictors

11) Infection And Inflammation Flashcards

(90 cards)