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Y2 Essential Medical Science > Mechanisms of Disease > Flashcards

Mechanisms of Disease Flashcards

1
Q

What is the meaning of the prefix ana-

A

Absence

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2
Q

What is the meaning of the prefix dys-

A

Disordered

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3
Q

What is the meaning of the prefix hyper-

A

Excess over normal

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4
Q

What is the meaning of the prefix hypo-

A

Deficiency below normal

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5
Q

What is the meaning of the prefix meta-

A

Change from one state to another

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6
Q

What is the meaning of the suffix -itis

A

Inflammatory process

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7
Q

What is the meaning of the suffix -oma

A

tumour

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8
Q

What is the meaning of the suffix -osis

A

State or condition

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9
Q

What is the meaning of the suffix -oid

A

Bearing a resemblance to

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10
Q

What is the meaning of the suffix -penia

A

Lack of

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11
Q

What is the meaning of the suffix -cytosis

A

Increased number of cells

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12
Q

What is the meaning of the suffix -ectasis

A

Dilation

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13
Q

What is the meaning of the suffix -plasia

A

Disorder of growth

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14
Q

What is the meaning of the suffix -opathy

A

Abnormal state lacking specific characteristics

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15
Q

What is hypertrophy

A

An enlargement of an organ or tissue from an increase in the size of its cells

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16
Q

What is hyperplasia

A

The enlargement of an organ or tissue caused by an increase in the reproduction rate of its cells

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17
Q

What is an embolus

A

A blood clot, air bubble, piece of fatty deposit, or other object which has been carried in the bloodstream to lodge in a vessel and cause an embolism

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18
Q

What is a thrombus

A

A blood clot formed in situ within the vascular system of the body and impeding blood flow.

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19
Q

What is a fistula

A

An abnormal or surgically made passage between a hollow or tubular organ and the body surface, or between two hollow or tubular organs.

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20
Q

What is dysplasia

A

The presence of cells of an abnormal type within a tissue

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21
Q

What is neoplasia

A

The presence or formation of new, abnormal growth of tissue

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22
Q

What is differentiation of cells

A

The process by which cells, tissue, and organs acquire specialized features, especially during embryonic development.

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23
Q

What is metastasis

A

The development of secondary malignant growths at a distance from a primary site of cancer

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24
Q

What are the general principles of immune response

A 
Multilayer defence
Network of pathogen recognition
Effective inter-cellular communication
Multiple mechanisms of pathogen clearance
Adaptive responses to changing pathogen
Self-regulation
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25
Q

What is autoimmunity

A

Theoretical concept
The system of immune responses of an organism against its own healthy cells and tissues
Genetically determined

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26
Q

What are autoimmune diseases

A

Distinct clinical entities
Breakdown of self-tolerance
Environmental factors acting on favourable genetic background

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27
Q

What are causative associations with autoimmune diseases

A

Sex: likely due to normal influence, more common in women than in men
Age : autoimmunity is more common in elderly
Environmental triggers: infection, trauma-tissue damage, smoking

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28
Q

What is the pathophysiology of autoimmunity

A

Autoreactive B cells and autoantibodies: directly cytotoxic, activation of complement, interfere with normal physiological function
Autoreactive T cells: directly cytotoxic, inflammatory cytokine production
General inflammation and end organ damage

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29
Q

What are the general clinical features of autoimmune diseases

A 
More than 100 different diseases
Can affect any organ
Onset in middle/old age
More common in elderly and in women
Leads to loss of organ function
Lifelong-chronic condition
Characteristic exacerbation and remission
Traditionally divided into organ specific or systemic
Common for diseases to overlap
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30
Q

What are organ specific vs systemic autoimmune conditions

A

Organ specific:
affect a single organ, autoimmunity restricted to auto antigens of that organ, overlap with other organ specific diseases, autoimmune thyroid disease is typical

Systemic:
affect several organs simultaneously, autoimmunity associated with auto antigens found in most cells of body, overlap with other non-organ specific diseases, connective tissue diseases are typical

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31
Q

What are examples of connective tissue diseases

A

Systemic lupus erythematosus
Scleroderma
Polymyositis
Sjorgrens syndrome

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32
Q

What are types of diagnostic tests for autoimmune conditions

A

Non-specific: inflammatory markers

Disease specific: autoantibody testing, HLA typing

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33
Q

What is HLA

A

proteins/marker on most cells in the body
Stands for human leukocyte antigens
Immune system uses HLA to recognize which cells belong in body and which do not

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34
Q

Why are autoantibodies measured

A 
Diagnostic
Early diagnosis
Pathogenic
Subtyping of patients
Monitoring of exacerbation/remission
Exclusion of diagnosis 
Cost of treatment
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35
Q

What is immunosuppression

A

A natural or artificial process which turns off the immune response, partially or fully, accidentally or on purpose

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36
Q

What is immunodeficiency

A

The lack of an efficient immune system-susceptibility to infections
Usually secondary to the effects of external factors
Some are primary immondeficiencies caused by genetic defects in individual components of the immune system
Type of infection is a guide to the underlying cause
Laboratory tests confirm

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37
Q

What are causes of secondary immunodeficiencies

A 
Stress
Surgery
Burns
Malnutrition
Cancer
Immunosuppressive effect of drugs
Irradiation
AIDS
Infections such as measles or TB
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38
Q

Define allergy and hypersensitivity

A 
A reaction produced by the normal immune system, directed against innocuous antigens, in a pre-sensitised immune host
Undesirable
Damaging
Uncomfortable
Sometimes fatal
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39
Q

What is type I hypersensitivity

A

Primary response:
IgE antibody mediated mast cell and basophil degranulation
Releases:
Histamine, proteases, chemotactic factors
Fast onset (15-30 mins)
Blanched weal appears surrounded by an area of redness (weal and flare)
Late phase response (lipid mediators):
Releases:
Eosinophils
Central role for Th2 T cell
Prostaglandin, leukotrienes

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40
Q

What is anaphylaxis

A

Medical emergency
An acute, potentially life threatening, IgE mediated systemic hypersensitivity reaction
Clinical symptoms:
Severe abdominal pain, vomitting, diarrhoea, hoarseness, cough, shortness of breath, wheezing and cyanosis, respiratory arrest, hypotension, dizziness, loss of consciousness

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41
Q

What is the atopic triad

A

Asthma, rhinitis and eczema

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42
Q

What are type II hypersensitivity reactions and their clinical relevance

A

Cytotoxic

Mechanism:
IgG/IgM Ab response against combined self/foreign antigen at the cell surface
Complement activation/ phagocytosis/ ADCC

Clinical features:
Onset minutes to hours
Cell lysis and necrosis

Common antigens:
Penicillin

Diseases resulting in this:
Good pasture’s nephritis
Blood transfusion reaction

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43
Q

What are type III hypersensitivity reactions and their clinical relevance

A

Immune complex

Mechanism:
IgG/ IgM Ab against soluble antigen immune complex deposition

Clinical features:
Onset 3-8hours
Vasculitis

Traditional cause:
Serum sickness

Associated diseases:
SLE

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44
Q

What are type IV hypersensitivity reactions and their clinical relevance

A

Delayed

Mechanism:
Antigen specific T cell mediated cytotoxicity

Clinical features:
Delayed onset 48-72 hours
Erythema induration

Common antigen:
Metals
Tuberculin test
Posion ivy

Associated diseases:
Contact dermatitis

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45
Q

Why do people get allergies

A

Components of the immune system responding to parasitic infection are also involved in allergic responses
The system has developed to produce a rapid tissue based response to re infection
Lack of infectious drive is a contributory factor
Combination of genetic and environmental factors

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46
Q

How are we sensitised

A

Allergen seen by dendritic cell -> presented to naïve T cell -> T cell differentiates into a Th2 cell -> secretes cytokines IL-4 and IL-13 which act as signals to naïve B cells -> naïve B cells become memory B cells which have specific IgE which will recognise the allergen on further exposure

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47
Q

What does the duel allergen exposure hypothesis suggest

A

Early cutaneous exposure to food protein through a disrupted skin barrier leads to allergic sensitisation, but early oral exposure to food allergen induces tolerance

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48
Q

What are the two types of cell adaptations

A

Hypertrophy: increase in muscle mass
Atrophy: decrease in muscle mass

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49
Q

What is necrosis

A

Severe cell swelling and rupture
Death of tissue following bioenergy failure and loss of plasma membrane integrity
Includes inflammation and repair

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50
Q

What is apoptosis

A

Internally controlled cell death
Individual cell deletion in physiological growth control and in disease
Activated or prevented by many stimuli
Increased apoptosis results in excessive cell loss

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51
Q

What is oncosis

A

Pre lethal changes preceding cell death

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52
Q

What are causes of cell injury

A 
Hypoxia
Physical agents: temperature, trauma, radiation
Chemical agents: drugs 
Immunologic reactions
Infectious agents
Genetic derangements
Nutritional imbalances
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53
Q

What is inflammation

A

A protective response to injury
Essential to survival
Aims to rid the body of the initial cause of the injury and consequences of such injury

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54
Q

What is acute inflammation

A

The initial tissue reaction to injury
Lasts minute, hours or days
Characteristic cell is the neutrophil polymorph
Blood vessel dilatation and increased permeability

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55
Q

What are the physical characteristics of acute inflammation

A 
Redness (rubor)
Heat (calor)
Swelling (tumor)
Pain (dolor)
Loss of function (function laesa)
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56
Q

What are causes of acute inflammation

A 
Physical agents
Infections
Hypersensitivity reaction
Chemicals 
Tissue necrosis
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57
Q

What are the major components of acute inflammation

A

Changes in vessel calibre
Increased vascular permeability and fluid exudate (rich in protein) formation
Cellular exudate formation

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58
Q

What is exudate

A

Extravasuclar fluid with high protein conc, containing cellular debris, implies inflammation

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59
Q

What is transudate

A

Low protein, little to no cellular components

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60
Q

What is oedema

A

Excess fluid in interstitial tissue/serous cavities

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61
Q

What is Pus

A

Inflammatory exudate rich in neutrophils, dead cell debris and microbes

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62
Q

How does the fluid exudate form

A

Increased permeability of microvasculature results in escape of protein rich fluid into tissue
Causes:
Chemical mediators (histamine, NO, leukotriene)
Direct vascular injury (trauma)
Endothelial injury (bacteria and toxins)

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63
Q

What are the effects of fluid exudate

A 
Dilution of toxins
Entry of antibodies 
Transport of drugs
Fibrin formation
Delivery of nutrients and oxygen
Stimulation of the immune response
High turnover
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64
Q

How does cellular exudate form

A

Loss of fluid into tissues and increased calibre of vessels-slower blood flow and increase viscosity of blood-stasis
Neutrophils line up along vascular endothelium, stick to endothelium and migrate through wall into tissues

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65
Q

What are neutrophils

A 
Produced in bone marrow
Commonest white cell in blood
Increase in acute inflammation 
Motile, amoeboid, can move into tissues
Directional chemotaxis
Short life span (hours in tissues)
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66
Q

What are chemical mediators of acute inflammation

A

Vasodilation
Migration of neutrophils
Chemotaxis
Increased vascular permeability

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67
Q

What are the cell derived mediators of acute inflammation

A 
Histamine
Prostaglandins
Lysosomal components
Leukotrines
Cytokines
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68
Q

What are the plasma derived mediators of acute inflammation

A

Complement system
Kinin system
Coagulation system
Fibrinolytic system

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69
Q

What are the results of acute inflammation

A

Usual result: resolution

Excessive exudate: suppuration -> discharge of pus or repair and organisation -> fibrosis

Excessive necrosis: repair and organisation -> fibrosis

Persistant causal agent: chronic inflammation -> fibrosis

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70
Q

What are the types of cell injury

A

Reversible: cell swelling, pallor, hydronic change, vacuolar degeneration

Irreversible: mitochondrial swelling, lysosomes swell, damage to membrane, leakage of enzymes

Ischaemic/reperfusion: new damage on repercussion mediated by free oxygen radicals

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71
Q

What are the types of necrosis and an example of each

A 
Coagulative: Myocardial infarction
Liquefactive: bacterial or fungal infection, CNS hypoxia
Gangrenous: limb ischaemia
Caseous: tuberculosis
Fat necrosis
Fibrinoid necrosis
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72
Q

What is coagulative necrosis

A

Commonest form
Occurs in most organs
Cells retain their outlines
Protein coagulate and metabolic activity ceases

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73
Q

What is liquefactive necrosis

A

Seen in brain
Due to lack of substantial supporting storm
Neural tissue may totally liquify

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74
Q

What is gangrenous necrosis

A

Putrefaction of the tissue
Cause is mostly infectious/ bacteria
Appear black
Types:
Wet- gangrene with superimposed infection
Dry- ischaemic coagulative necrosis only
Gas- Superimposed infection with gas producing organism

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75
Q

What is caseous necrosis

A

Tuberculosis is main cause
Structureless dead tissue
Amorphous pink material in centre with necrotic debris

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76
Q

What are the causes of fat necrosis

A

Enzymes

Trauma

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77
Q

When is fibrinoid necrosis present

A

In two conditions:
Malignant hypertension
Autoimmune diseases

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78
Q

What are the most important factors in determining the outcome of injury

A

The ability of the cells to replicate

The ability of the cells to rebuild complex architectural structures

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79
Q

What are the characteristics of Labile cell populations

A

High normal turnover
Active stem cell population
Excellent regenerative capacity
Eg Epithelia

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80
Q

What are the characteristics of Stable (quiescent) cell populations

A

Low physiological turnover
Turnover can massively increase if needed
Good regenerative capacity
Eg Liver, renal tubules

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81
Q

What are the characteristics of permanent cell populations

A

No physiological turnover
Long life cells
No regenerative capacity
Eg neurons, striated muscles

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82
Q

What are the characteristics of stem cell populations

A 
Prolonged self renewal
Asymmetric replication
Reservoirs present in many adult tissues
Located in specific areas 
Survival of stem cells is crucial to regeneration
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83
Q

What is the difference between healing by regeneration and by repair

A

Regeneration:
tissue returns to normal
Restitution of specialised function

Repair:
Fibrosis and scarring
Loss of specialised function

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84
Q

How do organisations 1 and 2 repair damaged cells

A

1:
The repair of specialised tissue by formation of a fibrous scar
Basic stereotyped pathological process
Production of granulation tissue and removal of dead tissue by phagocytosis

2:
Granulation tissue contracts and accumulates collagen, forming a scar
Organisation is a common consequence of pneumonia and infarction
Organised area - firm and puckered

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85
Q

What is granulation tissue made up of

A

New capillary loops
Phagocytic cells: neutrophils and macrophages
Myofibroblasts

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86
Q

What is healing by first intention from a surgical wound

A

Clean uninfected wound
Good haemostats
Edges opposed with sutures or staples

Edges joined by a thin layer of fibrin, eventually replaced by a collagen covered surface epidermis. Coagulated blood forms the scab. Fibrin join should not be disrupted. Epidermis grows over defect or if the wound is gaping then can grow down into defect but then usually stop growing and become reabsorbed but can remain and grow to form a keratin filed cyst

Only residual defect is the inability to reconstruct the elastic network within the dermis.

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87
Q

What is healing by second intention from a surgical wound

A 
Wound edges not apposed
Extensive loss of tissue
Apposition not physically possible
Large haematoma 
Infection 
Foreign body
Not a fundamentally different process from first intention
More Florid granulation tissues reaction
More extensive scarring

Healing by secondary intention tissue defect is larger. Becomes replaced by granulation tissue which eventually contracts leaving a scar

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88
Q

What are the factors that inhibit healing

A 
Local:
Infection
Haematoma
Blood supply
Foreign bodies
Mechanical stress
Systemic:
Age
Drugs
Anaemia
Diabetes
Malnutrition 
Catabolic states
Vit C deficiency
Trace metal deficiency
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89
Q

What is fracture healing

A

Haemorrhage around and within the bone
Haematoma is organised
Removal of necrotic fragments
Osteoblasts lay down disorganised woven bone (callus)
Romodelling according to mechanical stress
Replacement by more orderly lamellar bone

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90
Q

How does the brain heal

A

Neurones are terminally differentiated and supporting tissue is glial cells rather than collagen and fibroblasts etc and so these can proliferate. Hence damaged tissue is removed, often leaving cyst
Results in gliosis rather than scarring

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91
Q

What are the characteristics of chronic inflammation

A 
Innate and adaptive immunity
Lasts weeks, months, years
Angiogenesis, fibrosis
Macrophages, lymphocytes, plasma cells
Results in amyloidosis (protein misfold), cachexia, anaemia
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92
Q

What is chronic inflammation

A

Inflammation of prolonged duration
tissue destruction and repair happening at the same time
Mononuclear inflammatory cells
Fibrosis

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93
Q

What are the causes of chronic inflammation

A

Progression from acute inflammation
Recurrent episodes of acute inflammation
Persistent infection by certain microorganisms
Prolonged exposure to potentially toxic agents
Autoimmunity
Other unknown causes

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94
Q

What is a granuloma

A

Collection of activated epithelioid macrophages (pink cytoplasm, indistinct cell membranes, oval nucleus)

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95
Q

What is granulomatous inflammation

A

Granuloma
Surrounded by mononuclear leucocytes
Caseating or non-caseating
May also contain multinucleate giant cells

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96
Q

What is an atheroma

A

Intimal lesion that protrudes into a vessel wall.
Consists of a raised lesion with a soft core of lipid (mainly cholesterol and cholesterol esters) and is covered by a fibrous cap

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97
Q

What vessels are affected by atheroma

A 
Bifurcations
Abdominal aorta
Coronary arteries
Popliteal arteries
Carotid vessels
Circle of willis
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98
Q

What are the risk factors of atheroma

A 
Non-modifiable:
Increasing age
Male gender
Family history
Genetic abnormalities
Modifiable:
Hyperlipidemia (LDL:HDL)
Hypertension
Cigarette smoking
Diabetes
C-reactive proteins
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99
Q

What causes atherosclerosis

A 
Starts with damage or injury to the inner layer of an artery
Damage is caused by:
High blood pressure
High cholesterol
An irritant, such as nicotine
Certain diseases, such as diabetes
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100
Q

What is a fatty streak

A

The earliest lesion in atherosclerosis
Composed of lipid filled foamy macrophages
Begins as multiple minute flat yellow spots that eventually coalesce into streaks >= 1cm
These lesions are not significantly raised and do not cause disturbance
Not all fatty streaks are destined to progress to atheromatous plaque
Coronary fatty streaks begin to form in adolescence at the same anatomical sites that later tend to develop plaques

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101
Q

What is an atherosclerotic plaque

A

Consists of intimal thickening and lipid accumulation
Appears white yellow and superimposed thrombus on the plaque appears red
Plaque impinges on the vessel lumen

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102
Q

What is the sequelae of atherosclerosis

A

Rupture, ulceration or erosion of the intimal surface exposes the blood to highly thrombogenic substances and induces thrombosis then lumen occlusion then ischemia
Haemorrage into plaque
Atheroembolism
Aneurysm formation

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103
Q

What is a thrombus

A

A solid mass of blood constituents formed within the vascular system in vivo
Arterial thrombosis most commonly superimposed on atheroma
Venous thrombosis is most commonly due to stasis

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104
Q

What are the differences between a clot and a thrombus

A 
Clot:
Platelets not involved
Occurs outside vessel or inside
Red
Gelatinous 
Not attached to the vessel wall
Thrombus:
Platelets involved 
Occurs only inside vessel
Red (venous) or pale (arterial)
Firm
Attached to vessel wall
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105
Q

What is the sequelae of thrombosis

A 
Occlusion of vessel
Dissolution
Incorporation into vessel wall 
Recanalisation
Embolisation
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106
Q

What is an embolus

A

A mass of material in the vascular system able to become lodged in vessel and block its lumen
Most emboli are derived from thrombi
Most common - pulmonary embolus derived from deep vein thrombosis

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107
Q

What are the types of emboli

A 
Thrombus derived
Atheromatous plaque material
Vegetation on heart valves (infection carditis)
Fragments of tumour (causing metastasis)
Amniotic fluid
Gas
Fat
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108
Q

What is a systemic emboli

A

Generally originate from the heart or atheromatous plaque
Sequelae od myocardial infarction
Atrial fibrillation
Infective endocarditis - heart valve vegetations
Can cause - CVA, TIA, gangrene, bowel necrosis

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109
Q

What is hypoxia

A

A state of reduced oxygen availability in tissue which causes cell injury by reducing aerobic oxidative respiration
The effects can be reversible or can result in adaptation
If prolonged then tissue hypoxia causes necrosis
Causes:
Inadequate blood oxygenation
Decreased blood oxygen-carrying capacity
Ischaemia

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110
Q

What is ischaemia

A

Localised tissue hypoxia resulting from a reduction in blood flow to an organ or tissues
Most commonly caused by obstruction to arterial supply by mechanisms such as severe atherosclerosis, thrombosis, embolism

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111
Q

What is the difference between generalised hypoxia and ischaemia

A

Generalised hypoxia:
Impaired oxygen supply
Other metabolites still supplied

Ischaemia:
Decreased supply of metabolites including glucose
Glycolytic anaerobic respiration fails due to lack of glucose
Build up of metabolites impairs anaerobic respiration further
Ischaemia injures tissues faster/ more severely than generalised hypoxia

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112
Q

What is infarction

A

Tissue necrosis as a consequence of ischaemia

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113
Q

What is ischaemia repercussion injury

A

Generation of reactive oxygen species by sudden repercussion of ischaemic dysfunctional tissues

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114
Q

What are the main causes of infarction

A

Thrombosis/ embolism
Rupture/ thrombosis of atherosclerotic plaque

Most commonly in arterial vessels

Other rare causes:
Vasospam
Atheroma expansion
Extrinsic compression (tumour)
Twisting of vessel roots (volvulus)
Rupture of vascular supply (AAA)
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115
Q

How are infarctions classified

A 
Morphologically by colour
Red: haemorrhagic
Dual blood supply
Venous infarction
White: anaemic
Single blood supply hence totally cut off
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116
Q

What is a low-flow infarction

A

Infarction in areas of diminished blood flow in vulnerable anatomical regions

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117
Q

What is portal vasculature

A

Blood supplied via other parenchymal capillary beds

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118
Q

What are watershed regions

A

Point of anatomises between 2 vascular supplies

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119
Q

What is a pathophysiological state of shock

A

Reduced systemic tissue perfusion resulting in decreased oxygen delivery to the tissues
Causes a critical imbalance between oxygen delivery and oxygen requirements of the tissues
Impaired tissue perfusion and prolonged oxygen deprivation leads to cellular hypoxia and derangement of cellular biochemistry and eventually organ dysfunction

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120
Q

What is the result of shock

A

Cell death due to hypoxia
End organ damage
Multi organ damage
Death

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121
Q

What are the classifications of shock

A

Hypvolaemic:

Cardiogenic

Distributive: 
Anaphylactic
Septic
Toxic shock syndrome
Neurogenic
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122
Q

What is hypovolaemic shock

A

Intra-vascular fluid loss
decrease venous return to heart
decrease stroke volume
decrease cardiac output

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123
Q

What are the causes of hypovolaemic shock

A

Haemorrhage

Non-haemorrhagic fluid loss such as diarrhoea, vomiting and third spacing

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124
Q

What is third spacing

A

Acute loss of fluid into internal body cavities

This space losses are common postoperatively and in intestinal obstruction, pancreatitis or cirrhosis

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125
Q

What is cariogenic shock

A

Cardiac pump failure resulting in decrease in carbonmonoxide

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126
Q

What are the four categories of cariogenic shock

A

Myopathic
Arrythmia-related
Mechanical
Extra-cardiac

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127
Q

What does the effect of vascular occlusion depend on

A

Nature of blood supply
The rate of occlusion
The tissue vulnerability to hypoxia
The blood oxygen content

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128
Q

What are the characteristics of bacteria

A

Simple single cell organisms
Lack a membrane bound nucleus
Prokaryotes

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129
Q

What are the types of flagella

A 
They enable organisms to find sources of nutrition and penetrate host mucus
Monotrichous: one tail
Lophotrichous: many tails on one slide
Amphitrichous: One tail each side
Peritrichous: Tails all around
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130
Q

What are the fimbriae of a gram negative cell

A

Specialised structures that aid adhesion to host cells and colonisation

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131
Q

What is the function of the capsule or slime layer of bacteria

A

Polysaccharide material protecting bacteria from phagocytosis, desiccation, immune attack, antibiotics
Allows microorganism to pass through musus
Prevents complement-mediated killing

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132
Q

What are endospores

A

Metabolically inert form which are triggered by environmental factors and adapted for long term survival

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133
Q

How are bacteria classified

A 
Gram stain (ability to retain a crystal violet-iodine dye complex when cells are treated with acetone or alcohol)
Cell shape
Endospore
Atmospheric preference
Fastidiousness
Key enzymes
DNA (16S sequence)
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134
Q

How do bacteria replicate

A

Binary fission: cells divide into two identical daughter cells. asexual, creates new bacteria, no exchange of genetic material

Conjugation: transfer of transposable elements. sharing of transposable elements, creates no new bacteria, some genetic diversity

Transformation: picking up plasmids from the environment. creates no new bacteria, introduces some genetic diversity to the population.

Transduction: transfer of genetic information via a viral vector. introduces some genetic diversity into a population.

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135
Q

What are the characteristics of fungi

A

Eukaryotic
Most possess a cell wall made of chitin
Disease-causing fungi can be yeast like or moulds

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136
Q

What do moulds cause

A

Common, superficial infections such as ringworm and athletes foot
Uncommon, severe infections such as aspergillosis and mucormycosis

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137
Q

What is the structure of aspergillus

A

Grow in mats of tiny filaments known as hyphae that form mats called mycelia
Hyphae may or may not be subdivided into separate compartments by cross walls known as septa

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138
Q

How do fungi replicate

A

Sexual or Asexual

Via spores

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139
Q

What are the types of parasites

A

Protozoa: Unicellular eukaryotes-

  • Intestinal: Entamoeba, Glardia, Cryptosporidium
  • Non-intestinal: Plasmodium, Leishmania, trypanosoma

Helminths (worms):Multicellular eukaryotes-

  • Intestinal: Enterobius (pinworm), Taenia (tapeworm), Asceris (Roundworms)
  • Non intestinal: schistosoma
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140
Q

How are protozoa classified

A 
Generally classified according to morphology and means of locomotion
Flagellates: giardia
Amoebae: entamoeba
Cilliates: balantidium
Apicomplexa or sporozoa: plasmodium
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141
Q

How do protozoa replicate

A

Reproduce asexually by fission
May require a second or third host to complete lifecycle
May form hardy cysts

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142
Q

What are the characteristics of viruses

A

Obligate intracellular parasites
Every class of organism suffers from virus infection
Comprise a nucleic acid core wrapped in a protein coat called a capsid
Some viruses have an envelope made of lipid but some are naked
Rely entirely on other cells for their replication

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143
Q

How do viruses replicate

A
  1. Attachment/penetration: attachment proteins on virus bind receptors on cells, determines host-range, penetration by endocytosis or direct membrane fusion
  2. Uncoating: Genome is released from capsid during or after penetration, genetic material targeted to nucleus

3-5. Early viral proteins produced: using cellular machinery for transcription, encode viral enzymes, crucial for carrying out next stages in life cycle

3b: Genome replication: viral genetic replication occurs in host nucleus, many hundreds of thousands of new viral genomes can be produced

3-5. Late viral proteins produced: structural proteins of virus, capsid/surface proteins

  1. Viron assembly: genetic information assembles inside protein coat (nucleocapsid), for enveloped viruses, viral proteins concentrated at membrane with nucleocapsid and virus buds through membrane
    Viron release: lytic- bursts cell releasing visions and buds through plasma membrane, lysogenic- integrate into host cell DNA and replicate along with host cells, passed onto daughter cells, can transform to lytic cycle
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144
Q

How are viruses classified

A 
Essentially based on characteristics:
nature of nucleic acid (rna/ dna)
symmetry of the capsid
Presence or absence of an envelope 
Dimensions of the virion and capsid
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145
Q

What are prions

A

Misfolded protein
Unlike viruses they have no genetic material
Can be inherited and spread via contaminated material or occur spontaneously
Aggregate and cause misfoldng of native proteins (chain reaction)

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146
Q

What is pathogenicity and what are the requirements

A 
the capacity of a microorganism to cause an infection
Requirements:
transmissibility 
establishment in or on a host
harmful effect
persistence
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147
Q

What is virulence

A

Used interchangeably to describe pathogenicity
The degree to which a microorganism is able to cause disease
Allows a relative description of pathogenic potential

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148
Q

What is infectivity

A

the ability of a microorganism to. become established on/in a host
Mediated by microbial ligand and host cell surface receptor

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149
Q

What are virulence factors

A

Components of microorganisms which aid its ability to cause infection

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150
Q

What are the virulence factors

A

Facilitation of adhesion
Toxic effects
Tissue damage
Interference with host defence mechanisms
Facilitation of invasion
Modulation of the host cytokine responses

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151
Q

What are the routes of transmission

A

Faecal-oral
Blood borne
Respiratory
Direct contact

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152
Q

What is the incubation period

A

Period between infection with the organism and manifestation of clinical features

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153
Q

What is the period of infectivity

A

Period during which a transmissible organism may be transmitted to another person

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154
Q

What is the impact of infection on the host

A 
Inflammation
Abscess formation
Excessive host response to endotoxin
Toxic effects pf endotoxin
Granuloma formation
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155
Q

What is the meaning of colonisation

A

Establishment at a site in the body

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156
Q

What is microbiota

A

All the organisms in a given community

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157
Q

What is the microbiome

A

All the genes present within the microbiota

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158
Q

What does symbiosis mean

A

Two or more organisms co-exist in close physical association

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159
Q

What does normal flora/ microbiota mean

A

organisms found in a given location in a state of health

160
Q

What are the types of symbiosis

A

Mutualism: Both organism benefit from symbiosis

Neutralism: Neither organism derives benefit or harm

Commensalism: One organism benefits, the other derives neither benefit nor harm

Parasitism: One organism (parasite) benefits at the expense of the other (host)

161
Q

What are non-sterile and sterile sites

A

Non-sterile: have normal flora

Sterile sites: No normal flora

162
Q

What factors influence what organisms colonise what areas

A 
Moisture 
Temperature
pH
O2 availability
Nature of surface
163
Q

What are the characteristics of skin

A 
Variable temperature
Dry
Subject to abrasion
Aerobic environment
Nutrient-poor
Skin surface components
Skin flora:
Coagulase-negative staphylococci
Staphylococcus aureus
Propionibacterium species
164
Q

What are the characteristics of the gingival crevice (between teeth and gums)

A 
Constant temperature
Moist 
Few physical challenges
Anaerobic environment
Bathed in nutrients
Mucosal surface components
165
Q

What is the mouth flora

A

Viridans/oral streptococci
Anaerobes
Many others

166
Q

What are the nasopharyngeal flora

A 
Nostrils: skin flora, S. aureus
Pharynx: Respiratory and other pathogens:
Streptococcus pyogenes
Haemophilus influenzae
Streptococcus pneumoniae
Neisseria meningitides 
S. aureus
167
Q

What is the vagina flora

A

Pre-puberty:
Skin flora
Lower GI flora (E.coli)

Post-puberty:
Lactobacillus spp. Lactobacillus acidophilus
- Ferment glycogen
-Maintain pH=3, preventing overgrowth of other species
Skin flora
A few C. albicans

168
Q

What is the GI tract flora

A

Stomach and small intestine: low gastric pH inhibits bacterial growth
Predominantly aerobic bacteria:
acid-tolerant lactobacilli
Helicobacter pylori

Large intestine:
95-99% anaerobes: bactericides spp. clostridium spp. bifidobacteria spp
Aerobic bacteria: enteric gram-negative bacilli: escherichia coli, klebsiella spp. enterobacter spp. proteus spp. citrobacter spp.

169
Q

What are the benefits of normal flora

A

Metabolism: synthesis secondary metabolites/ vitamins
Colonisation resistance
Induction of cross-reactive antibodies

170
Q

what are the characteristics of C diff

A 
Hospital acquired infection
Main risk factor is antibiotic treatment
Perturbation of normal colonic microflora allows C diff overgrowth
Leads to toxin production 
Diarrhoea. Pseudomembranous colitis
171
Q

What are the pathologies of normal flora

A

Overgrowth
Translocation
Cross infection

172
Q

What are the clinical effects of acute hyperammonaemia toxicity

A 
Lethargy 
Poor feeding
Vomiting
Tachypnoea
Convulsions
Coma
Death
It is a medical emergency and must be acted upon immediately
173
Q

What are some signs of acute porphyria

A 
Severe abdominal pain
Pain in chest, legs or back
Constipation or diarrhoea
Vomiting
Insomnia
Palpitations
High Blood pressure
Anxiety
Seizures
Mental changes
Breathing problems
Muscle pain/ tingling/ weakness/ paralysis
Red or brown urine
174
Q

What are possible signs of photosensitive porphyria

A 
Sensitivity to the sun/ artificial light
Sudden painful erythema and oedema
Blisters that take weeks to heal 
Itching 
Fragile skin
Increased hair growth
Red or brown urine
175
Q

What are the mechanisms of disease of inborn errors of metabolism

A

Accumulation of toxin
Energy deficiency
Deficient production of essential metabolite/ structural component

176
Q

What is the result of energy deficiency

A

Causes crisis presentations in defects of fatty acid oxidation

177
Q

What is the result of defective receptors

A

Leads to androgen insensitivity syndrome

178
Q

How are Inborn errors of metabolism diagnosed

A

Pre-symptomatic screening

Investigation of symptomatic individuals

179
Q

How are investigations of suspected inborn errors of metabolism in patients carried out

A

Metabolite testing
More complicated metabolite testing
Enzyme analysis/functional studies
Mutation/gene analysis

180
Q

What is investigated in basic urine metabolic screening

A 
Spot tests
Organic acids
Amino acids
Sugar Chromatography
Oligosaccharides/sialic acids
Mucopolysaccharides
181
Q

What are the benefits of diagnosing inborn errors of metabolism

A

Treatment, improve prognosis
Identify cause of clinical problem
Genetic counselling
IEM act as models for other disorders

182
Q

What is screened for Pre-natally

A

Neural tube defects:
Maternal serum and amniotic fluid
Ultrasound scan at 16 weeks

Down syndrome:
1st trimester: PAPA, HCG and nuchal translucency
2nd trimester: maternal serum AFP, HCG, inhibit and estriol
Test on the ascent

183
Q

How is normal pH range maintained

A

Heavily dependent on buffers and excretion of CO2 and nitrogenous waste

184
Q

How is H+ produced

A

Glucose incomplet metabolism (anaerobic) (glucose -> 2 lactate and 2 H+)
Triglycerides incomplete metabolism - ketogenesis (triglycerides -> free fatty acids + H+, free fatty acids -> ketones + H+)
Amino acid metabolism ureagenesis (metabolism of neutral amino acids results in the generation of H+)

185
Q

What is a buffer

A

A solution which resists change in pH when an acid or base is added
Buffering ensures H+ ions are transported and excreted without causing damage to physiological processes

186
Q

What are the functions of acids and bases

A

Acids are H+ donors (HCL-> H+ + CL-

Bases are H+ acceptors (OH- + H+ -> H2O)

187
Q

What is pH

A

Negative logarithm of the hydrogen ion conc (mol/L)

pH= -log10[H+]

188
Q

What is acidaemia

A

Low blood pH

189
Q

What is acidosis

A

Abnormal process or condition that lowers arterial pH

190
Q

What is Ka

A

Acid dissociation constant

Ka = ([A-][H+]) / [HA]

191
Q

What is pKa

A

Negative logarithm of Ka
pKa = -log10Ka
The lower the pKa, the stronger the acid

192
Q

What is the Henderson- Hasselbalch equation

A

Explains how acids and bases contribute to pH and therefore [H+]
pH = pKa + log10 ([base]/[acid])
Therefore pH is proportional to [HCO3-]/ pCO2

193
Q

What is the equation that is central to acid-base balance

A

H+ + HCO2- H2CO3 CO2 + H2O

194
Q

What are the details of bicarbonate

A

Acts as a buffer, mopping up H+ ions
However it cannot buffer CO2
Equilibrium of CO2 requires non-bicarbonate buffers

195
Q

What are the details of phosphate

A

Monohydrogen phosphate and dihydrogen phosphate form a buffer pair

196
Q

What are the details of ammonia

A

Ammonia and ammonium ions form a buffer pair

197
Q

How can proteins act as buffers

A

They contain weakly acidic and basic groups due to their amino acids composition and so can accept and donate H+ ions to some extent

198
Q

What are the sites of acid base metabolism and how

A

Liver: Dominant site of lactate metabolism (Cori cycle), only site of urea synthesis (waste product of ammonia metabolism

Lungs: secretion of CO2, rate of elimination is equal to the rate of production so that blood pCO2 remains

GI tract: H+ secreted into stomach as HCL, Bicarbonate secreted by pancreas into duodenum -> needed to neutralise acid from stomach

Kidneys: Excretion of H+ in distal tubule, Reabsorption of bicarbonate in proximal tubule, Regeneration of bicarbonate in distal tubule

199
Q

What is the oxyhemoglobin dissociation curve

A

The amount of o2 bound to Hb is determined by the pO2
Relationship is described but the curve
Curve shifts to the right where Hb has reduced affinity for O2 when:
Body temp increases
Patient is hypoxic or anaemic (increase 2,3 DPG)
[H+] increases

200
Q

What is lactic acidosis

A

Can result from increase production (e.g. anaerobic gylcolysis) or decreased consumption (e.g. liver disease)
A form of metabolic acidosis

201
Q

What is hyperammonaemia In liver failure

A

Liver is unable to perform urea cycle which normally converts toxic ammonia to urea for excretion in urine

Ammonia stimulates the respiratory centre causing the patient to hyperventilate and blow off CO2 -> leads increase in blood pH -> known as respiratory alkalosis

202
Q

What is androgenesis

A

development of an embryo containing only paternal chromosomes due to failure of the egg to participate in fertilization.
Develops in an abnormal way to form hydatidiform moles.
Proliferation of abnormal trophoblast tissue and can develop into malignant trophoblastic tumour and results in no remaining embryo

203
Q

What is parthenogenesis

A

Reproduction from an ovum without fertillization, especially as a normal process in some invertebrates and lower plants
Results in ovarian teratoma

204
Q

What are pharmacokinetics

A

What the body does to the drug

205
Q

What are Pharmacodynamics

A

What the drug does to the body

206
Q

What is stratified medicine

A

Selecting therapies for groups of patients with shared biological characteristics

207
Q

What is personalised medicine

A

Therapies tailored to the individual

208
Q

What are pharmacogenetics

A

The study of inherited genetic differences in drug metabolic pathways which can affect an individuals response to drugs

209
Q

How do genetic variations effect drugs

A 
Absorption
Activation
Altered target
Catabolism
Excretion
210
Q

What are the consequences of getting the pharmacogenetics wrong

A

Inactive drug - poor/ no response
Overactive drug - Excess toxicities (adverse reaction)
Financial costs to health services

211
Q

How can genetics help in prescribing the correct medications

A

Identify genetic variations that lead to altered outcomes

Change dose of drug where appropriate

Use a different drug that works better

Guide new targeted drug development

Reintroduce effective drugs which have ADR in few patients

Stratified/ personalised medicine

Reduce financial costs of inappropriate treatment

212
Q

How is the acid-base status of a patient determined

A

Blood gas machine measures:

Gases; pCO2, pO2
Metabolites: Glucose, lactate
Electrolytes: Sodium, Potassium, Chloride, Calcium
Co-oximetry: Total Hb, O2 saturation, OxyHb, COHb, MetHb
pH
Derived parameters: base excess, standard bicarbonate, total CO2, anion gap

213
Q

What are the HCO3- levels and pCO2 levels for primary metabolic and respiratory acidosis and alkalosis

A

Metabolic acidosis: decreased HCO3-
Metabolic alkalosis: increased HCO3-
Respiratory Acidosis: Increased pCO2
Respiratory Alkalosis: decreased pCO2

214
Q

What are the levels of pH for academia and alkalaemia

A

pH < 7.35 = academia

pH > 7.45 = alkalaemia

215
Q

What are respiratory and metabolic compensation

A

Respiratory compensation are changes in CO2 for metabolic disturbances

Metabolic compensation are changes in HCO3- for respiratory disturbances

Compensatory mechanisms aim to restore a neutral pH

216
Q

What are the causes of metabolic acidosis

A

Increased acid formation: ketoacidosis, lactic acidosis, poisoning, inherited organic acidosis
Decreased acid excretion: Uraemia, RTA type 1
Loss of bicarbonate: GI (Diarrhoea, fistula), Renal (RTA type 2, carbonic anhydrase inhibitors)
Acid ingestion

217
Q

What is the physiological response to metabolic acidosis

A

Buffering:
Acute increased [H+] resisted by bicarbonate buffering, causing decreased HCO3-

Compensation:
Respiratory: Respiratory centre stimulated -> hyperventilation to blow off CO2, self-limiting as generates additional CO2
Renal: Urine H+ excretion maximised, increased rate of regeneration of bicarbonate

218
Q

How is metabolic acidosis managed

A

Identify and treat cause
Sodium bicarbonate by IV if pH < 7.00 or orally in CKD, RTA types 1 and 2

Rapid correction impairs O2 delivery, rebound alkalosis is possible

219
Q

What are the causes of metabolic alkalosis

A

Administration of bicarbonate
Potassium depletion
Loss of H+ through vomiting

220
Q

What is the physiological response to metabolic alkalosis

A

Buffering:
release of H+ from buffers
Compensation:
Respiratory: Reduced rest rate in order to retain CO2, Self-limiting as an increase in pCO2 stimulates the resp centre
Renal: Difficult, decreased GFR leads to high bicarbonate reabsorption, potassium deficiency contributes to persistence of alkalosis

221
Q

How is metabolic alkalosis managed

A

Treat underlying cause

Treat factors that sustain alkalosis such as replace the potassium

222
Q

What are the causes of respiratory acidosis

A

Defective control of respiration:
CNS depression
CNS disease
Neurological disease

Defective respiratory function:
Mechanical
Pulmonary disease

223
Q

What is the physiological response to respiratory acidosis

A

Buffering: limited buffering by haemoglobin
Compensation:
Respiratory: increased pCO2 stimulates respiratory centre but disease prevents adequate response
Renal: maximal bicarbonate reabsorption, almost all phosphate excreted as H2PO4-, Marked increase in urinary NH4+

224
Q

How is respiratory acidosis managed

A

Treat underlying cause
Maintain adequate arterial pO2 but avoid loss of hypoxic stimulus to respiration
Avoid rapid correction of pCO2 as risk of alkalosis due to persistence of compensation

225
Q

What are the causes of respiratory alkalosis

A

Central: Head injury, stroke, hyperventilation, drugs, sepsis, chronic liver disease

Pulmonary: pulmonary embolism, pneumonia, asthma, pulmonary oedema

Iatrogenic: excessive mechanical ventilation

226
Q

What is the physiological response to respiratory alkalosis

A

Buffering: release of H+ from non-bicarbonate buffers

Compensation:
Respiratory: Inhibitory effect of decreasing pCO2 overwhelmed by primary cause
Renal: Decreased renal regeneration of bicarbonate (CO2 is substrate, therefore CO2 is preserved)

227
Q

How is respiratory alkalosis managed

A

Treat underlying cause
Rapid symptomatic relief by re-breathing
Sedation or prevention of hyperventilation by mechanical ventilation

228
Q

What do U and Es measure and estimate

A

Measure: Sodium, potassium, chloride, bicarbonate, urea, creatinine
Estimate: Water

229
Q

What does epidemiology examine

A

Who gets the disease

230
Q

What does aetiology examine

A

What causes the disease and what can stop it

231
Q

What is a dendritic cell

A

Circulating the body, sampling environment and showing it to immune system

232
Q

What is an antibody

A

Circulate, specific to certain proteins

233
Q

What is a macrophage

A

Phagocytic cell

234
Q

What are the results of histamine

A 
Blood clots
Gastric acid secretion
blood vessels dilate
Bronchoconstriction
Increases the permeability of the capillaries
Adrenaline is released
Swelling and inflammation
Frequent heartbeat
235
Q

How are people sensitised to antigens

A

Dendritic cell presents antigen, naive T cell differentiates into a Th2 cell, secretes cytokines IL-4 and IL-13 which act as signals to Naive B cells which become memory B cells which have specific IgE that will recognise the allergen on further exposure

236
Q

What is the atopic march

A

The typical progression of allergic diseases that begin in early life, includes eczema, food allergy, asthma, hay fever.

237
Q

How are allergies tested

A

Skin prick test
Intra dermal test
Oral challenge test
History taking

238
Q

How is a skin prick test conducted

A

Positive control of histamine
Negative control of saline
Samples pricks of various antigens

239
Q

What is the blood transfusion reaction

A

If incorrectly matched blood
Dendritic cells detect foreign antigen
Presents to B cells which make antibodies
Activates complement and have cytotoxic action
MAC attack complex (classical pathway)
Takes hours to a day

240
Q

What is an autopsy

A

An examination of a body after death to determine the cause of death

241
Q

Why are postmortems important

A

To document accurate data about the health of the population
Notification of communicable diseases
For education
To help catch the bad guy
To explain what happened to their loved one and aid the grieving process
Genetic testing
Provides evidence for legal proceedings

242
Q

What are the types of postmortems

A

Coroners postmortems (don’t need consent)
Hospital/ consent postmortems (needs consent)
CT postmortems

243
Q

How do you perform postmortems

A

External exam
Evisceration
Dissection of organs
Reconstruction

244
Q

What can be found in external examination

A 
Rigor mortis
Decomposition
Hypostasis (blood moves to areas due to gravity)
Ligature mark 
Old surgical scars
Stab wounds
245
Q

What happens in the evisceration stage

A 
Removal of organs
Cut in most efficient ways
Clip off the anterior rib cage
Removal of the small and large intestines
Then remove all the organs
246
Q

The presence of which lines in solidified blood is diagnostic of pre-mortem thrombus

A

Lines of Zahn

247
Q

How is the body reconstructed after a post mortem

A

All the organs go in a biodegradable bag in the body cavity and brain cavity is stuffed with cotton wool

248
Q

What is the difference between stage and grade of a tumour

A

Stage: how far it has spread
Grade: How differentiated the cells are

249
Q

What are the types of pathology

A 
Histopathology
Haematology
Immunology
Cytopathology
Microbiology
Chemical pathology
Genetics
Toxicology
Forensics
250
Q

What are the general principles of immune response

A 
Protects us from threats in the environment
Multilayer defines
Network of pathogen recognition
Effective inter-cellular communication
Multiple mechanisms of pathogen clearance
Adaptive responses to changing pathogen
Self-regulation
Limitation of host damage
251
Q

What are the proteins of the innate system

A

Cytokines: chemical signals which modulate cell activity or attract cells
Acute phase proteins: opsonise or present pathogens to the immune system
Complement proteins

252
Q

What causes autoimmune disease

A

Immune regulation
Genetic make up Environment (infection, trauma-tissue, smoking)
Sex (hormonal influence)
Age (autoimmunity more common in elderly)

253
Q

How does the coroner assess death

A

Who
When
Where
How

254
Q

Why should you report a death to the corner

A 
Unnatural
cause of death is not known
Not seen by a Dr within 14 days (or after death)
trauma, violence or suspicions
accident                
workplace incident or industrial disease
suicide or self harm
poisoning or drugs overdose (prescribed or illicit)
neglect involved (or self neglect)
Prison or police custody
Mental Health Act section
surgical procedure or anaesthetic implicated
medical mismanagement or medical device
anything odd
255
Q

What is a malignant epithelial tumour

A

Carcinoma

256
Q

What is the most common type of autopsy

A

Coroners

257
Q

What is histopathology

A

It involves the investigation and diagnosis of disease from the examination of tissues

258
Q

What is degranulation

A

The release of pre-formed mediators from mast cells

259
Q

What is cytopenia

A

The reduction in the number of blood cells

260
Q

What is the prognosis

A

The term used to describe the anticipated course of a disease in terms of cure, remission or fate of the patient

261
Q

What is pathogenesis

A

The mechanisms through which the aetiology of a disease produces its clinicopathological effects

262
Q

What is bronchiectasis

A

Widening of the bronchi or their branches

263
Q

What is anaplasia

A

The lack of a normal differentiated state, usually in a tumour

264
Q

What is a granuloma

A

An infectious or foreign material that can’t be degraded or removed and becomes engulfed in inflammatory tissue

265
Q

What is DiGeorge syndrome

A

Thymic aplasia leading to lack of T cells

266
Q

What does SCID mean

A

The immundeficiency seen in infants in which there is a failure of both T and B lymphocyte function

267
Q

What does regeneration depend on

A

Tissue cell kinetics
Architecture
Stem cell survival

268
Q

How can fracture healing go wrong

A 
Misalignment 
Movement
Infection (more common in compound fractures)
Interposed soft tissue
Pre-existing bone bathology
269
Q

What is an ulcer

A

A local defect or excavation of the surface of an organ or tissue that is produced by sloughing of inflammatory necrotic tissue

270
Q

What is a skin ulcer

A

Loss of area of epidermis and dermis to produce a defect even down to fat, muscle, tendons and bone

271
Q

What are the causes of leg ulcers

A 
Vascular 90%
-Venous 70%
-Arterial 10%
-Mixed 10%
Others 10%
272
Q

What are the rarer causes of leg ulcers

A

Inflammatory (pyoderma gangrenous, panniculitis)
Neuropathic (peripheral neuropathy)
Malignant (SCC, BCC, lymphoma)
Vascular (vasculitis and CTD
Iatrogenic (pressure sores, drugs)
Infection (bacterial, fungal)
Metabolic (diabetes mellitus, calcinosis cutis)
Traumatic (accidental/ self induced)
Burns (chemical, electrical, thermal, radiation)

273
Q

What are the risk factors of venous leg ulcers

A

Valvular incompetence (primary or secondary)
Previous damage to venous system (DVT, hypertension, peripheral oedema)
Obesity, immobility (poor muscle contraction -> venous pooling and hypertension

274
Q

What are we looking for in a history about venous leg ulcers

A

Varices veins
Leg swelling
Blood clots in deep veins
Sitting or standing for long periods of time
End of day throbbing and aching in the calf muscles
High blood pressure
Multiple pregnancies (increased circulating volume)
Previous surgery
Obesity
Increasing age and immobility

275
Q

What are we looking for upon examination about venous leg ulcers

A

Medial gaiter area most common
Less painful than arterial ulcer
Superficial, sloughy with ill defines borders
Associated signs of chronic venous hypertension

276
Q

What causes arterial ulcers

A

Associated with peripheral vascular disease
Plaque build up in arteries that carry blood to lower limbs which hardens and narrows the arteries
Limits flow of oxygen rick blood to legs and other parts of body
Plaques made up of fat, cholesterol, calcium, fibrous tissue, and other substances in the blood

277
Q

What are risk factors for arterial ulcers

A 
Diabetes 
Smoking
High blood lipids
High blood pressure
History of ischaemic heart disease, cerebrovascular disease or peripheral vascular disease
Renal failure
Obesity
Rheumatoid arthritis
Clotting and circulation disorders
278
Q

What are we looking for in a history about arterial leg ulcers

A

Intermittent claudication
Rest pain or paraesthesia
Pain at ulcer site
Other symptoms of vascular disease eg angina

279
Q

What are we looking for upon examination of arterial leg ulcers

A 
Punched out painful ulcer
Lower leg/foot
Loss of hair appendages
Dry skin
Cool peripheries
Pale or cyanotic or pre-gangrenous toes
Position dependent ischaemia
Reduction in proximal and or peripheral pulses
280
Q

What are the features of neuropathic ulcers

A

Due to distal polyneuropathy (motor/ sensory/ autonomic)
Under metatarsal heads/ heel
Painless but warm with pulses

281
Q

What are the causes of neuropathic ulcers

A 
Diabetes
Other causes of polyneuropathy 
-Alcohol
-B1/B12 deficiency
- Charcot Marie Tooth
282
Q

Why would a biopsy of an ulcer be performed

A

Clinically atypical ulcer

To exclude or diagnose malignancy

283
Q

How are leg ulcers managed

A

Treat the underlying cause of the ulcer
Treat the ulcer
Treat any associated infection
Debride necrotic material (remove slough/dead tissue)

284
Q

What are the outcomes of acute inflammation

A

Resolution:

  • phagocytosis of insulting agent
  • fibrinolysis
  • phagocytosis of debris

Repair:

  • organisation (replacement by granulation tissue)
  • fibrous scar

Chronic inflammation:

  • organisation
  • macrophages/ lymphocytes/ plasma cells
285
Q

What causes a granulomatous inflammation

A

Bacterial (TB, leprosy)
Parasitic (schistosomiasis)
Fungal (histoplasma, cryptococcus)
Inorganic metals or dust (silicosis, berylliosis)
Foreign body (suture, vascular graft)
Unknown (sarcoidosis, ulcerative colitis)

286
Q

What are examples of granulomatous diseases

A

Tuberculosis

Sarcoidosis

287
Q

What is an abscess

A

A localised collection of pus surrounded and walled off by a collection of capillaries, neutrophils and fibroblasts

288
Q

What is an example of a stable cell

A

Hepatocyte

289
Q

What’s the most common type of leg ulcers

A

Venous

290
Q

What is an exudate

A

Term used to describe protein-rich fluid associated with vascular leakage during acute inflammation

291
Q

What is fibrosis

A

Common feature of chronic inflammation involving thickening and scarring of connective tissue

292
Q

What term is used to describe bacteria that are able to cause the formation of pus

A

Pyogenic

293
Q

What condition involves a chronic abscess in the bone marrow cavity

A

Osteomyelitis

294
Q

What cell type secretes antibodies

A

Plasma cell

295
Q

What is the type of necrosis associated with TB granulomas

A

Caseous

296
Q

What is the transudate

A

Fluid that is low in protein with little or no cellular component

297
Q

What is cholecystitis

A

Chronic inflammation of the gallbladder

298
Q

What is pavementing

A

Term used to describe the adhesion of neutrophils to the vascular endothelium at sites of acute inflammation

299
Q

What is cirrhosis

A

Clinical end-point of chronic inflammation of the liver

300
Q

What cells are macrophages derived from

A

Monocytes

301
Q

What colour do gram positive bacteria cells show as

A

Purple

302
Q

What colour do gram negative bacteria cells show as

A

Red

303
Q

What is the cycle of infection

A

Encounter -> entry -> spread -> evade defences -> multiply and damage -> disperse

304
Q

What are endogenous sources of infection

A

Microorganisms from the host getting into the wrong place

305
Q

What are exogenous sources of infection

A

Organisms originating from the external environment/ infected individuals

306
Q

What is bacterial pneumonia

A 
Infection of lower respiratory tract
Causes fluid to collect in the alveoli of the lungs
Can be caused by:
Streptococcus pneumonias
Staphylococcus aureus
Haemophilus influenzae
307
Q

What is Gonorrhoea

A 
STI
Caused by neisseria gonorrhoea
Symptoms:
-Discharge of pus from urethra
-burning sensation
-sterility
Sex bias to symptoms
308
Q

How is Bacterial pneumonia encountered

A

Inhalation of air-borne droplets containing pathogen
Contact with mouth of infected individual
Contaminated blood

309
Q

How is gonorrhoea encountered

A

Sexual contact with infected individual
Contact with urethral exudate
Vertical transmission (mother to child during birth)

310
Q

What is the role of secretory immunoglobulin A (IgA) and where is it found

A

Found in mucosal secretions of respiratory tract and urogenital tract
Bind to pathogens and prevent them from adhering to host tissues

311
Q

What is IgA protease

A

AN endopeptidase
Produced by S. pneumonia and N. gonorrhoeae
Degrades IgA
Targets amino acid sequence Pro-Pro-Y-Pro (Y= threonine, serine or alanine)
Breakdown products of IgA to stick to the outside of the pathogen

312
Q

What is the incubation period

A

Period of time between infection with the organism and manifestation of clinical features

313
Q

What is the period of infectivity

A

Period during which a transmissible organism may be transmitted to another person

314
Q

How do pathogens multiply and cause damage

A

Need to acquire nutrients from the host to multiply

Can cause direct damage or indirect damage

315
Q

What are hyaluronidase and neuraminidase

A

Enzymes capable of degrading hyaluronic acid and sialic/neuraminic acid

316
Q

What are hyaluronic acid and neuraminic acid

A

Both are targets as are components of interstitial cement in connective tissues (Hyaluronic) or epithelial cells (neuraminic)
Breakdown of these can provide nutrients, more space for organism to grow and activates immune system

317
Q

What is endotoxin

A

Component of the outer membrane in N. gonorrhoeae
Isn’t actively secreted
Released on cell death/lysis
Can cause uncontrolled activation of immune response: inflammation, severe tissue damage, multiple organ failure (sepsis)

318
Q

What is the host response to endotoxin

A 
Severe sepsis and or septic shock
T-lymphocyte response:
-cytokine release
-fever, riggers, hypotension, tachycardia, collapse
-cardiac and/or renal failure
Activation of the clotting cascade:
-disseminated intravascular coagulation
-depletion of clotting factors
Activation of complement
319
Q

What is inflammation due to infection

A

Response to invasion/ tissue damage
Activation of complement and clotting systems, fibrinolysis and kinin system
Leukocyte adhesion and production of inflammatory mediators:
-local vasodilation
-reduction in endothelial barrier function
-increased vascular permeability
Phagocytosis of foreign material

320
Q

What is erythema due to inflammation

A

Vasodilation causes increased blood flow

321
Q

What is swelling due to inflammation

A

Increased vascular permeability allows extravasation of serum proteins and leukocytes,
swelling arises from consequent physical and osmotic effects

322
Q

What is the cause of pain in inflammation

A

A number of different physical and biochemical changes in inflamed tissues

323
Q

What is the cause of heat in inflammation

A

Increased blood flow

324
Q

Why is there loss of function in inflammation

A

Secondary effect of swelling and pain

325
Q

What is an exotoxin

A 
Protein produced (and usually secreted) by living bacteria
Typically have quite specific effects on host
326
Q

What is tetanus

A 
Clostridium tetani
Infection of dirty wounds
Toxin production:
tetanospasmin
-produced on germination of spores
binds to nerve synapses
-inhibits release of inhibitory neurotransmitters
Death caused by respiratory paralysis
327
Q

What are the types of TB

A

Primary TB: Ranke/Ghon complex: solitary granuloma with hilarious granulomatous

Post primary/ reactivation: Widespread granulomatous inflammation +/- cavitation, often apical

Miliary TB: Multiple disseminated 1-3mm pulmonary granulomas

Extrapulmonary TB: Diverse manifestations in bone, liver, kidneys, CNS etc

328
Q

How does the host induce dispersal in certain examples

A

Inflammation of lung tissue:

  • Production of fluid containing pathogen
  • Induction of coughing
  • Dispersal of pathogen via respiratory droplets

Damage to tissues of the genital tract and induction of immune response:

  • Production of urethral discharge
  • Dispersal via sexual contact
329
Q

What is biochemical genetics

A

The study/ investigation of genetic disorders that affect the metabolic pathways of cells

330
Q

What are the clinical effects of acute hyperammonaemia

A

Ammonia accumulates in patients with urea cycle defects

Lethargy
Poor feeding
Vomiting
Tachypnoea
Convulsions
Coma
Death

Medical emergency

331
Q

What happens in porphyrias

A

Porphyrins accumulate

332
Q

What are the signs of photosensitive porphyria?

A 
Accumulation of Uroporphrin, coproporphrin, protoporphrin
Sensitivity to the sun/artificial light
Sudden painful erythema and oedema
Blisters that take weeks to heal
Itching
Fragile skin
Increased hair growth
Red or brown urine
333
Q

What are the signs of acute porphyria?

A 
Accumulation of ALA and PBG
Severe abdominal pain
Pain in chest, legs or back
Constipation or diarrhoea
Vomiting
Insomnia
Palpatation
Hypotension
Anxiety
Seizures
Mental changes
Breathing problems
Muscle pain, tingling, weakness, paralysis
Red or brown urine
334
Q

What is the pathway of fatty acid oxidation

A

Triglycerides -> fatty acids -> fatty acid oxidation -> Acetyl CoA -> ketones/ TCA cycle -> energy

335
Q

How are inborn errors of metabolism diagnosed

A

Pre-symptomatic screening:

  • whole population
  • selected groups

Investigation of symptomatic individuals:

  • test body fluids for abnormal metabolites
  • measure enzyme activities
  • histochemical/immunochemical staining
  • DNA analysis
336
Q

What is the route for investigating those with potential inborn errors of metabolism

A

Metabolite testing -> more complicated metabolite testing -> enzyme analysis/functional studies -> mutation/gene analysis

337
Q

What is screening

A

The process of identifying apparently healthy people who may be at increased risk of a disease or condition.

338
Q

What are the Wilson and Hunger criteria of screening programmes

A 
Disease must be sufficiently common
Natural history must be known
Early therapeutic intervention beneficial 
Acceptable and affordable screening test
Diagnostic confirmatory test
339
Q

What happens in newborn screening in the UK

A

All babies tested at day 5-8
Most samples taken in community by midwives
Regional laboratories perform tests and report results
Standards set by the UK Newborn Screening Program Centre
Nature of the programme defines by the national screening committee

340
Q

What is on a newborn screening card

A

NHS number, name, address, DOB, GP, mother’s details, DOS, gestation, weight, transfusion status, hospital status, repeat status

341
Q

Why are samples in newborn screening poor quality

A 
Spots of blood not soaked through
Too small a spot
Spotted from both sides or compressed
Multiple spotting
Contaminated
Expired card
Missing details
Too young for screening
342
Q

What are the newborn screening standards

A

Timely collection of samples
Timely processing of samples and reporting data
Timely collection of repeats
All positive cases to be on treatment with referral within 3 days and by a set time frame (condition dependent)
All babies to be tested, including those identified as missed or incomers, up to one year of age

343
Q

What is phenylketonuria

A

Severe intellectual disability if untreated
Excellent prognosis if treated from birth
Screening test is a bloodspot phenylalanine
Confirm diagnosis with plasma phenylalanine measurements

344
Q

What is the natural history of untreated PKU

A 
Severe intellectual disability
Seizures, tremors
Spasticity
Behavioural problems, irritability
Eczema in childhood
345
Q

What is the treatment of PKU

A

Low phenylalanine diet
Bioprotein Supplementation
Large neutral amino acids

346
Q

What is congenital hypothyroidism

A

Severe developmental delay if untreated
Excellent prognosis if treated from birth
Screening test is a bloodspot TSH
Confirm diagnosis with plasma thyroid function tests
Treatment with thyroxine, carefully monitored

347
Q

What are haemoglobinopathies

A

Early detection and treatment of sickle cell disease

Also detect carriers and compound heterozygotes with HbC/Dpunjab, E/Oarab, B-thalassaemia major

348
Q

What is Maple syrup urine disease

A

Defect in branched chain 2 ketoacid dehydrogenase complex
Clinical effects:
Majority have the classical disease, presenting during the neonatal period, encephalopathy and cerebral oedema blush’s poor feeding, ketoacidosis and seizures
Screening target is leucine

349
Q

What is Homocystinuria

A

Defect in B-cystathionine synthase
Clinical effects:
Usually healthy at birth, diagnosis not usually made until 2-3 years
Myopia followed by dislocation of the lens, osteoporosis, thinning and lengthening of the long bones, mental retardation and thromboembolism
Without treatment 25% will die before age of 30 due to thromboembolism
Screening target is methionine
Secondary target is total homocysteine

350
Q

What is a tumour

A

A swelling or mass of any kind

351
Q

What is neoplasia

A

New uncontrolled growth of cells that is not under physiological control
Can be benign or malignant

352
Q

What is a cancer

A

A generic term for a large group of diseases characterised by the growth of abnormal cells beyond their usual boundaries that can then invade adjoining parts of the body and/or spread to other organs

353
Q

What are the hallmarks of cancer

A 
Sustaining proliferating signalling 
Evading growth suppressors
Avoiding immune destruction
Enabling replicative immortality
Activating invasion and metastasis
Inducing angiogenesis
Resisting cell death
Deregulating cellular energetics
354
Q

What is embryological histogenesis

A

The formation of differentiated tissues from undifferentiated endoderm, ectoderm and mesoderm

355
Q

What is tumour histogenesis

A

Tumours are named according to the tissues from which they arise

356
Q

What is tumour differentiation

A

The extent to which a neoplasm resembles its tissue of origin

357
Q

What are the meanings of each level of tumour differentiation

A

Well-differentiated: neoplasm closely resembles tissue of origin
Moderately-differentiated: neoplasm shows some resemblance to tissue of origin
Poorly-differentiated: neoplasm does not resemble tissue of origin

358
Q

What is anaplasia

A

A neoplasm that is poorly differentiated and highly pleomorphic

359
Q

What are the most common cancers in females in the UK

A

Breast 31%
Lung 13%
Bowel 10%

360
Q

What are the most common causes of cancer deaths in females in the UK

A

Lung 21%
Breast 15%
Bowel 10%

361
Q

What are the most common cancers in males in the UK

A

Prostate 26%
Lung 14%
Bowel 13%

362
Q

What are the most common causes of cancer deaths in males in the UK

A

Lung 21%
Prostate 14%
Bowel 10%

363
Q

What are the differences between benign and malignant tumours

A

Benign:

  • Neoplasm does not invade surrounding tissues
  • Does not metastasise
  • slow rate of growth
  • usually well differentiated
  • Rarely fatal

Malignant:

  • neoplasm does invade surrounding tissues
  • may metastasise
  • fast rate of growth (division exceeds cell death)
  • Well -> moderate -> Poorly -> anaplastic
  • Often fatal
364
Q

How can a tumour cause effects

A

Effects of primary tumour
Effects of distant metastases
Paraneoplastic syndromes

365
Q

What are the effects of primary tumour

A

Invasion into and replacement of normal tissues/ organs -> failure of that organ to function

Pressure on normal tissue -> failure of that organ to function

Invasion into blood vessels -> bleeding

Pressure on blood vessels -> ischaemia

Pressure/invasion into nerves -> loss of nerve function/ pain

Growth into lumen -> obstruction

Ulceration

366
Q

What are the effects of distant metastases

A

When a cancer spreads to different parts of the body forming new (secondary) tumours

Invasion into/ pressure on organsnormal tissues
Invasion into/ pressure on vessels
Invasion into/ pressure on nerves
Growth into lumen

367
Q

What are paraneoplastic syndromes

A

Signs and symptoms that are not related to local effects of the primary tumours

Develop as a result of either -proteins/ hormones secreted by tumour cells
-Immune cross reactivity between tumour cells normal tissues

368
Q

What is cancer cachexia

A

Where the tumour uses the energy stored in fat and muscle causing tissues to waste away

369
Q

What is the stroma

A

Cells that support the parenchyma

370
Q

What is the parenchyma and some examples

A

Cells that perform actual function of an organ
Eg:
Cells that do gas exchange (pneumocytes) in the lungs
Cells that contract in the heart (myocytes) causing it to contract

371
Q

What do stroma contain

A

Many cell types

  • blood vessels
  • fibroblasts
  • immune cells
372
Q

What makes up the breast

A 
Chest wall 
Pectoralis major
Lobile
Nipple
Areola
Lactiferous duct
Adipose tissue
Skin
373
Q

How often is a breast lump cancerous

A

~20% of the time

374
Q

What is the triple assessment of breast cancer

A

Clinical: examination
Imaging: Ultrasound or mammogram
Pathology: biopsy and/or cytology

375
Q

What are the features of a lump

A 
Mobile (benign) or fixed (malignant)
Well defined (benign) or not (malignant
Smooth (benign) or irregular (malignant)
Firmness (soft then benign and firm then malignant)
Location
376
Q

What are worrying nipple symptoms of breast cancer

A

Inversion
Rash
Discharge

377
Q

What are the skin changes of breast cancer

A

Tethering or retraction
Oedema
Peau d’orange
Ulceration/fungating lesion

378
Q

What are the clinical P codes of breasts

A 
P1 normal
P2 Benign lesion
P3 Atypical, probably benign lesion
P4 Atypical, probably malignant lesion
P5 Malignant
379
Q

How do things appear in a mammogram

A

Fat: radiolucent so black

Solid masses: radio-opaque so white

380
Q

How do things appear in an ultrasound

A

Fat: hypoechoic so white

Fibroglandular breast tissue echogenic so black

381
Q

What are the imaging R codes

A 
R1  Normal
R2  Benign lesion
R3  Atypical, probably benign lesion
R4  Atypical, probably malignant lesion
R5  Malignant
382
Q

What are the pathology B codes

A 
B1  Normal
B2  Benign lesion
B3  Atypical, probably benign lesion
B4  Atypical, probably malignant lesion
B5  Malignant
383
Q

What are the pathology C codes

A 
C1  Insufficient
C2  Normal or Benign lesion
C3  Atypical, probably benign lesion
C4  Atypical, probably malignant lesion
C5  Malignant
384
Q

What are BRCA gene mutations

A

Genes that encode tumour suppressor proteins are critical for cells to repair damaged DNA
Gene mutation: proteins not made or don’t work properly - DNA damage in cells not repaired properly
~70% change of developing Breast cancer by 80
Peak incidence at lower age

385
Q

What is cell adaptation

A

Cellular changes in response to changes in environment or demand

386
Q

How can a cell adapt

A 
Size 
Number
Phenotype
Metabolic Activity
Function
387
Q

Why do cells adapt

A

Acquire new, steady state of metabolism and structure
Better equipped to survive
Failure may lead to sub-lethal or lethal cell injury

388
Q

Can epithelial cells adapt and why

A

Labile cell population
Active stem cell compartment
Highly adaptive in number and function

389
Q

Can fibroblast cells adapt and why

A

Survive severe metabolic stress without arm

EG lack of oxygen

390
Q

Which cells cannot adapt and why

A

Cerebral neurons
Terminally differentiated and permanent cell population
Highly specialised function and easily damaged

391
Q

What are the two types of cellular adaptation

A

Physiological: responding to normal changes in physiology or demand

Pathological: responding to disease related changes

392
Q

What is atrophy

A

Reduction in size of organ or tissue by decrease in cell size and number

393
Q

What are examples of atrophy

A

Physiological: Embryogenesis, uterus after pregnancy or menopause

Pathological: localised or generalised

394
Q

What are the causes of pathological atrophy

A 
Decreased workload (disuse atrophy)
Loss of innervation (denervation atrophy)
Diminished blood supply
Inadequate nutrition (cachexia)
Loss of endocrine stimulation
Pressure
395
Q

What is metaplasia

A

Transformation of one differentiated cell type into another
Transdifferentiation of stem cells
Better adaptation to new environment
Can affect epithelium and mesenchymal tissues
Physiological or pathological

396
Q

What is dysplasia

A

Earliest morphological manifestation of multistage process of neoplasia
In-situ disease; non invasive
Shows cytological features of malignancy but no invasion

397
Q

What is a carcinoma in situ

A

A group of abnormal cells

Y2 Essential Medical Science (2 decks)

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