Mechanisms of Disease Flashcards
Define apoptosis
Programmed cell death by intracellular programmes (degradation of DNA/proteins)
Apart from TB name three other granulomatous infections.
-Leprosy -Cat-scratch disease -Syphilis -Chronic fungal infections -Xanthogranulomatous pyelonephritis
Define aplasia
Complete failure of a specific tissue or organ to develop
Define arteriosclerosis
The thickening of the walls of arteries and arterioles, usually as a result of hypertension or diabetes mellitus
Define atheroma
The accumulation of intracellular and extracellular lipid in the intima and media of large and medium sized arteries
Define atherosclerosis
The thickening and hardening of arterial walls as a consequence of atheroma
Define disease.
The consequence of failed homeostasis with consequent morphological and function disturbances
Define chronic inflammation.
Chronic response to injury with associated fibrosis
Define atrophy
Shrinkage of a tissue or organ due to an acquired decrease in size and/or number of cells
Define dysplasia
Abnormal maturation of cells within a tissue
Define hyperplasia
Increase in tissue or organ size due to increased cell numbers.
Define hypertrophy
Increase in tissue or organ size due to increased cell size.
Define hypoplasia
Incomplete development of a tissue or organ
Define metaplasia
Reversible change of one DIFFERENTIATED cell type to another.
Define necrosis
Changes after cell death in living tissue
Describe the appearance of caseous necrosis
It looks like cheese - contains an amorphous (structureless) debris
Define regeneration.
The replacement of dead or damaged cells by functional, differentiated cells
Describe the appearance of an arterial thrombi?
Pale, granular, low cell count and lines of Zahn
Describe the appearance of a venous thrombi?
Deep red, soft, gelatinous and a high cell count
Describe the basic structure of the collagen molecule
-Glycine every third position -3 alpha chains -Left handed triple helix -Mostly hydroxyproline and proline residues in other positions
Describe the differences in the appearance of benign and malignant tumour to the naked eye.
-Benign - grow in a confined local area and so have a pushing outer margin -Malignant - irregular outer margin and shape and may show areas of necrosis and ulceration
Describe the features of coagulative necrosis
-Histologically the structure is preserved creating “ghost outlines” -After this the tissue goes through acute inflammation and there is a mass immigration of phagocytes and neutrophil polymorphs -Increased eosinophilia of cytoplasm
Describe the features of liquefactive necrosis
-Liquefaction of tissues -Massive neutrophil immigration
Describe the four steps of infiltration of neutrophils.
- Margination - neutrophils line up at the edge of blood vessels along the endothelium 2. Rolling - neutrophils roll and begin to stick 3. Adhesion - fully stick 4. Emigration
Describe the mechanism of fibrous repair.
1) Inflammatory cells infiltrate the blood clot (neutrophils digest, macrophages + lymphocytes are recruited)
2) Angiogenesis occurs where capillaries/lymphatics sprout and myo/fibroblasts migrate and differentiate laying down ECM and collagen
3) Cell population falls, collagen increases and the myofibroblasts pull it together - left with a fibrous scar.
Describe the healing of a bone fracture.
1) Haematoma - forms from ruptured vessels within marrow cavity and periosteum. Haematoma allows for an invasion of macrophages, endothelial cells fibroblasts and osteoblasts allowing necrotic tissue to be removed and for capillaries develop.
2) Soft callus - bone is laid down in an irregular woven pattern, sometimes with islands of cartilage
3) Hard callus - Woven bone replaced with more organised lamellar
4) Remodelling - the bone is shaped by stresses of different movements N.B. a callus is described as a specialised mixture of cells
Describe the macroscopic appearance of atheroma
-Fatty streak (yellow bumpy lipid deposits at the intima) -Simple plaque (irregular outline, raised white/yellow colour) -Complicated plaque (thrombosis, haemorrhage, calcification or aneurysm)
Describe the microscopic appearance of atheroma
-Early changes - proliferation of smooth muscle cells, lots of foam cells and extracellular lipids -Later changes - fibrosis, necrosis, inflammatory cells and cholesterol clefts
Describe the normal structure of an artery from inside to outside.
-Endothelium -Sub-endothelial connective tissue -Internal elastic lamina -Muscular media -External elastic lamina -Adventitia
Describe the process of degradation and phagocytosis in apoptosis
-Cell breaks into membrane-bound fragments that are taken up by neighbouring cells or phagocytes. -Membrane bound “apoptotic bodies” express proteins on their surface that are essential for phagocytosis by neighbouring cells.
Describe the process of angiogenesis in wound healing.
1) Endothelial proteolysis of basement membrane 2) Migration of endothelial cell via chemotaxis 3) VEGF causes endothelial proliferation 4) Endothelial maturation and tubular remodelling 5) Recruitment of periendothelial cells - become the pericytes and smooth muscle tissue of the blood vessel, they are important in maintaining the stability of the blood vessels.
Describe the systemic effects of alcohol abuse.
- Liver - alcoholic cirrhosis and acute hepatitis
- Nervous system - thiamine deficiency produces degeneration of nerve cells
- CV system - cardiac muscle degeneration causing cardiomyopathy, hypertension and arrythmias
- GI system - gastritis/pancreatitis
- Skeletal muscle - Rhabdomyolysis and chronic myopathy
Describe the three main stages of the change of blood flow during acute inflammation.
- Transient vasoconstriction 2. Vasodilatation of arteries/capillaries (increased bloodflow/redness) 3. Increased permeability (exudation of protein rich fluid into tissues)
For benign neoplasms which effects of the growth are the most relevant?
-Local effects -Hormonal effects
Give a physiological and pathological example of hyperplasia
-Physiological causes - proliferative endometrium, bone marrow at altitude -Pathological Causes - thyroid goitre
Give a physiological and pathological example of hypertrophy
-Physiological causes - skeletal muscle and pregnant uterus (hypertrophy + hyperplasia) -Pathological causes - ventricular cardiac muscle hypertrophy, bladder smooth muscle hypertrophy
Give an example of one physiological and one pathological role of apoptosis.
-Physiological - Web space loss in embryogenesis -Pathological - Graft versus host disease
Give five functions of the extracellular matrix.
-Supports and anchors cells -Separates tissue compartments e.g. basement membrane -Sequesters growth factors -Allows communication between cells -Facilitates cell migration
Give the anagram commonly used for collagen synthesis and briefly outline what each letter stand for.
CHASPOGRL: -Cleavage of signal peptide -Hydroxylation of proline/lysine residues -Addition of N-linked oligosaccharides -Sulphide bond (di) formation -Procollagen - formation of triple helix -O-linked glycosylation -Golgi then exocytosis -Removal of terminal peptides (procollagen peptidase) -Lateral aggregations to form fibrils
Give two ways in which the immune system can damage cells?
-Hypersensitivity -Autoimmune
How are inflammatory cells recruited in fibrous repair?
Chemotaxis
How are malignant cells transported to distant sites?
1) Blood vessels (via capillaries and venules) 2) lymphatic vessels 3) Fluid in body cavities (pleura, peritoneal, pericardial and brain ventricles)
How can an aspirin overdose cause problems?
Stimulates respiratory centre resulting in a respiratory alkalosis. Compensatory mechanisms result in a metabolic acidosis – fall in pH indicates serious poisoning
How can atheroma be prevented?
-Stop smoking -Modify diet -Treat hypertension -Treat diabetes -Lipid lowering drugs
How can endothelial injury occur?
-Raised LDL -‘Toxins’ e.g. cigarette smoke -Hypertension -Haemodynamic stress
How can you diagnose alcoholic hepatitis?
-Elevated serum bilirubin -Elevated aminotransferases -Elevated alkaline phosphatase -Elevated prothrombin time
How can you diagnose someone with excessive alcohol intake?
-Elevated MCV - macrocytic (due to damaged bone marrow/folate deficiency) -Raised AST and ALT -Raised Gamma-GT
How do growth factors promote proliferation in the stem cell population?
Extracellular signals transduced into the cell. There promote expression of genes controlling cell cycle.
How do malignant cells take advantage of nearby non-neoplastic cells?
Form “cancer niches” where the normal cells provide some growth factors and proteases
How do neutrophils move? What chemical mediators are required?
Chemotaxis by: -C5a -LTB4 -Bacterial peptides
How does angiogenesis occur in fibrous repair?
Platelets, ECM and others produce angiogenic cytokines in response to hypoxia e.g. VEGF, bFGF
How does contact between the basement membranes & adjacent cells control the rate of cell division?
Contact inhibition - signalling through adhesion molecules inhibits proliferation in intact tissue. If this contact is lost proliferation occurs.
How does pain and loss of function combat injury?
Enforces rest (stops further injury)
How does smooth muscle proliferation occur during atheroma?
Endothelial damage leads to increased platelets and PDGF which then leads to smooth muscle proliferation
How does the exudation of fluid combat injury?
-Delivers plasma proteins (immunoglobins, fibrinogen, inflammatory mediators) -Dilutes toxins -Increases lymphatic drainage (so it delivers micro-organisms to phagocytes and antigens to immune system)
How does the body go about resolving acute inflammation using chemical mediators?
-All chemical mediators of acute inflammation have short half-lives, some can be degraded (heparinase) or inhibitors may bind (anti-proteases) -Chemical mediators may be diluted in the exudate -Lipoxins, endothelin
How does the fibroblast and ECM proliferation occur in fibrous repair?
Macrophages produce various pro-fibrotic cytokines, e.g. IL1, TNF alpha, TGF beta
How does the increased smooth muscle cause increased foam cells?
Proliferation and migration of smooth muscle takes the lipid with it. Macrophages arrive and phagocytose the fat, becoming foam cells
How does the infiltration of cells combat injury?
Removes pathogenic organisms/necrotic debris
How does vasodilatation combat injury?
-Increases delivery -Increases temperature
How is the vascular wall made more permeable during acute inflammation?
Chemical mediators: -Histamine, leukotrienes cause endothelial contraction which creates gaps -Cytokines IL-1 and TNF cause cytoskeletal reorganisation which creates gaps -VEGF which creates channels across endothelial cytoplasm
How is apoptosis initiated and executed?
-Intrinsic - Everything required is in the cell - usually due to the response to DNA damage by p53. Causes mitochondria to be more permeable, release cytochrome c, mixes with caspase 9 and APAF1 to form an apoptosome activates caspases -Extrinsic - an external ligand (TRAIL or Fas) bind to a death receptor resulting in caspase activation
How long can a cell survive hypoxia?
Trick question…mwhahaha Some neurones can only stand a few minutes, however, some fibroblasts in the dermis can stand hours.
How might fat necrosis be diagnosed? Why can you use this method?
X-rays - free fatty acids released and they react with calcium to form chalky deposits in fatty tissue
In general what is a neoplasm?
An abnormal growth of cells that persists after the initial stimulus is removed
In what cell populations can hyperplasia occur?
Labile/stable cell populations
In what type of cell population do germ cell neoplasms arise?
Pluripotent
In which three ways can chronic inflammation arise?
-Take over from acute inflammation (if damage is to severe to be resolved) -Arise anew (by some chronic low level irritation i.e. RA) -Alongside acute inflammation (when there is severe/repeated irritation)
Increasing tumour burden and cytokine release due to secondary neoplastic effects canlead to what presentation?
-Reduced appetite and weight loss -Cachexia -Malaise -Immunosuppression (can also be due to direct bone marrow destruction) -Thrombosis.
List five causes of acute inflammation.
-Microbial -Tissue necrosis -Hypersensitivity -Physical agents -Chemical agents
List four of the main thrombin inhibitors
Anti-thrombin III, Alpha 1 anti-trypsin, Alpha 2 macroglobulin and Protein C/S
List some irreversible changes of hypoxia
-Huge cystolic Ca2+ increase -Several enzymes activated resulting in cell death
List some reversible changes of hypoxia
-Increased anaerobic respiration producing lactate and therefore lowering pH -Low ATP means Na+ accumulates in cells -Cell swells via osmosis -Detachment of ribosomes which leads to decreased protein synthesis
Name some common causes of cirrhosis? (replacement of liver tissue by fibrosis, scar tissue and regenerative nodules)
-Alcohol -Infection with HBV, HCV -Fatty liver disease -Drugs and toxins
Name three types of giant cell and explain in which condition they are commonly seen in.
-Langhans cells - TB -Foreign Body cells - any foreign body, commonly sutures -Touton cells - fat necrosis
Neoplasms originating in what area most commonly metastasise to the bone?
-Breast -Bronchus -Kidney -Thyroid -Prostate
Other than pancreatitis, what else can cause fat necrosis?
Also can occur after direct trauma to fatty tissue (for example breast tissue)
Other than thrombosis suggest other causes of embolism
-Nitrogen -Air -Amniotic fluid -Medical Equipment -Tumour cells
Suggest some common sites for blood borne metastasis.
-Lung -Bone -Liver -Brain
Suggest some common sites of atheroma
-Abdominal aorta -Coronary arteries -Carotid arteries -Cerebral arteries -Leg arteries
Suggest some miscellaneous systemic effects of neoplasms.
-Neuropathies affecting the brain and peripheral nerves -Skin issues (pruritis and abnormal pigmentation) -Fever -Myositis
What abnormal accumulations are seen under a light microscope during cell injury in alcoholic liver disease?
-Keratin deposition (Mallory’s hyaline) -Fat deposition
What are acute-phase proteins? Give examples of some of these proteins.
Proteins that concentrations increase or decrease in response to inflammation. For example: C-reactive protein, a1 antitrypsin, haptoglobin, fibrinogen etc.
What are blastomas?
Occur mainly in children and are formed from immature precursor cells
What are amyloidosis?
A variety of conditions where normally soluble proteins become insoluble and are deposited in the extracellular space of various organs or tissues, disrupting normal function.
What are cells with no resemblance to any tissue called?
Anaplastic
What are giant cells? When does it usually occur?
Multinucleate cells made by fusion of macrophages, usually occurs during frustrated phagocytosis.
What are initiators of mutation? Give some of the main examples
Mutagenic agents - chemicals, infections, and radiation are the main initiators
What are neutrophils?
Neutrophils are a type of granulocyte and are the primary type of white blood cell involved in inflammation.
What are paraneoplastic syndromes?
Indirect systemic effects of neoplasms. (e.g. includeeffects of increasing tumour burden, secreted hormones etc.)