Block 9 - Disease Processes (1) Flashcards
What is disease a consequence of?
Failed homeostasis
What are the two types of morphological changes?
Microscopic changes which eventually turn macroscopic
Which is the acidic and basic dye in the haematocyclin-eosin stain?
Haematocyclin = basic (purple) Eosin = acidic (pink)
4 main disease targets in a cell?
Cytoskeleton, Ionic channels, Membrane, Mitochondria
Define autophagy
The cell ‘eats’ itself
Triggered by calcium influx
Define karyorrhexis
Large fragments
Define atrophy
Decrease in cell size and number
What are the three stages of necrosis?
Coagulative –> Colliquative/Liquefaction –> Caesating
Define coagulative necrosis
Cell death but structure retained
Pale cytoplasm, decreased nuclei
Define colliquative/liquefaction necrosis
Hydrolytic enzymes from dying cells degrade tissue
Fluid-filled cavity of necrotic cells
Define caesating necrosis
Accumulation of inflamamtory cells
Structure lost but not fluid
3 structural chromosome abnormalities
Break, reattach, inverted incorrectly
Define PLOIDY
Additional chromosome
Definer restituation
When the opposite DNA strand is used as a template
Define dysplasia
Abnormal cell apperance
Define metaplasia
The cell differentiates into a different type of cell
Define immunopathology
The damage from the immune system becomes more clinically significant than the thing it was defending
Type 2 hypersensitivity:
What antibodies are involved?
Two types of tissue cytotoxicity?
6 examples
IgG or IgM
Antibody or complement dependent cytotoxicity
Goodpasture, Myasthenia gravis, Grave’s disease, Rhesus disease, Drug allergies, Drug induced haemolytic anaemia
Type 3 hypersensitivity:
What antibody is involved
3 examples
IgG
Arthur’s reaction (vaccination)
Serum sickness
Lupus
Type 4 hypersensitivity:
Explain the primary and secondary response
What is a Hapten?
What class of diseases also come under this?
4 examples
Primary: Sensitisation and memory cell production when APC presents Haptens (sensitising agents that bind to self-proteins in the epidermis –> neoantigens)
Secondary: APC with hapten presents to CD4+ cells –> T cell and macrophage activation
Autoimmune diseases
Contact sensitisation, Rheumatoid arthritis, MS, Allergen skin tests
What layer of skin is found in thick skin but not in thin skin?
2 characteristics
Stratum lucidium
Thin, transparent layer between the granulosum and corneum
What is different about the stratum corneum and hypodermis in thick skin?
Corneum is thicker
Hypodermis has more angualtion
What epithelium is the skin?
Stratified squamous
What are the 4 layers of the epidermis?
Stratum corneum –> Stratum granulosum –> Stratum spinosum –> Stratum basale
What happens at the stratum corneum?
How are the cells arranged?
What is the main property of the cells?
Apoptosis
Tight junctions form a barrier
Lipids and insoluble proteins = hydrophobic
What two things are found in the stratum granulosum?
Lamellar bodies: Lipids for hydrophobic barrier
Reratohyalingranules: Proteins which bind to keratin
How many layers are in the stratum spinosum?
What pigment is present?
What protein structures are present?
Many layers
Keratin
Tonofibrils: Cytoplasmic protein structures that meet at desmosomes
What 2 cells are found in the stratum basale?
Single layer of cuboidal cells
Stem cells which proliferate in a 40 day cycle
What are the four cells found in the skin?
Which is the most abundant?
What are their roles?
Keratinocytes - most abundant, more in high layers
Langerhans - Dendritic APC
Merkel - Fine touch
Melanocytes - more in low layers
What causes scaling
Imbalance between loss and renewal
Shedding of the cornified layer
What causes blisters
Breakage of the cell-cell junctions
3 roles of the dermis?
Protection
Thermoregulation
Touch
Papillary dermis:
Thickness
Type of connective tissue
3 properties
Thinnest
Loose connective tissue
Fine collagen and elastin
Squiggles to provide blood
Reticular dermis:
Thickness
Type of connective tissue
2 properties
Thickest
Dense and irregular connective tissue
Thick collagen fibre
Immune cells and cell appendages
How are nails produced?
What is their structure?
Nail root cells in the basal layer proliferate to form the nail matrix
Similar to the straum corneum and contains keratin
Where is hair produced?
Hair follicle from the acini in the basal layer
What is the structure of hair?
Medulla - Cortex - Cuticle
What are the three phases of hair growth?
Anagen - Growth phase
Catagen - Transition phase
Telogen - Resting phase
What type of glands are sebaceous glands?
What do they secrete?
How do they secrete?
Branched acinar
Secretes sebum: A lipid which keeps hair soft and waterproof
Holocrine secretion: Increased lipid concentration causes rupture of cell membrane
What type of glands are eccrine and apocrine glands?
Where are they?
How do they secrete?
Coiled tubular
Reticular dermis
Merocrine secretion: Secrete directly onto skin
Which glands become active in puberty?
Apocrine
What are the 5 stages of healing of deeper wounds?
Haemostasis: Fibrin clot Inflammation Fibroplasia: Fibroblasts --> collagen Epithelialisation: Keratinocytes create new layers Remodelling
2 examples of liquid-filled lesions
Where are they found?
Blister, pustule
Epidermis
3 examples of solid lesions
3 causes
Plaque, nodule, wheal
Increased epidermal thickness, tumour, oedema
2 examples of lesions in skin colour
2 causes
Patch, erythema
Changes in blood flow, melanocytes
What causes a callus?
Hyperplasia of the epidermis following pressure/friction
What causes an ulcer?
Loss of epidermis and papillary dermis
3 requirements of fluid homeostasis
Intact vessels, osmolarity and constant pressure
How much blood do you need to lose to go into hypovolemic shock?
20%
What are the three stages of haemostasis?
Haemorrhage: Bleeding
Thrombosis: Clotting
Fibrinolysis: Clot dissolution
2 causes of a decrease in plasma proteins
Liver cirrhosis
Malnutrition
4 causes of lymphatic obstruction
Parasitic worm
Malignancy
Surgery
Radiation therapy
What causes the formation of a thrombus?
Inappropriate haemostasis caused by endothelial injury, abnormal blood flow and hypercoagulability
Main component of an arterial and venous thombus
Arterial: Platelets
Venous: Fibrin and electrolytes
2 reasons why there is an increase in blood flow to a tissue
Hyperaemia
Congestion
When does hyperaemia occur?
What are the two types?
A change in environment
Reactive: Vasodilation due to decreased oxygen or increased waste
Active: Vasodilation due to exercise
What is congestion?
What are the two types?
Decreased blood removal due to impaired venous return
Local: Vessel compression
Systemic: Heart failure, oedema
How does shock cause cell injury and damage?
Decreased blood flow (systemic hypoperfusion) due to decreased cardiac output causes decreased nutrients to cells
Define cardiogenic shock
3 examples
Failure of the heart to pump sufficient blood to damage
e.g. MI, Arrhythmia, Pulmonary oedema
Define neurogenic shock
CNS damage –> loss of systemic stimulation of blood vessels –> blood pooling
Define sepsis
Uncontrolled systemic reaction to the infection causes organ dysfunction
Define septic shock
Profound circulatory, cellular and metabolic abnormalities which increase mortality
Pathophysiology of sepsis
> Bacteria activate neutrophils and macrophages
Systemic release of cytokines causes systemic vasodilation, hypotension and vascular leakage
Oedema decreases blood pressure more and decreases blood flow to organs, decreasing nutrient exchange
Complement activated
Dysregulation of immune and haemostatic systems causes respiratory distress and multiple organ failure
Are parasites eukaryotes or prokaryotes?
Eukaryotes
What are the two classes of prokaryotes?
Archaea: Virus and prion
Bacteria
3 ways to classify bacteria?
Cell wall
Morphology
Nutritional and biochemical properties
What is found on the peptidoglycan layer?
Tecchoic acid
What do you use to stain Gram+ and Gram- bacteria?
Crystal violet
Retained in Gram+, lost in Gram -
Stain with counterstain
Not seen in Gram+ but seen in Gram-
Which class of bacteria can make spores?
Gram positive
Define microaerophilic
Requires some oxygen but not a lot
How do you identify bacteria?
PCR and genome sequencing
What are the 4 methods of horizontal gene transfer?
Transformation: DNA released into environment and taken up
Transduction: Phage transfers non phage DNA
Conjugation: Bacteria have sex
Transposons: Genetic units which jump
What are the 4 phases of bacterial replication?
- Lag phase: Bacteria make the right conditions
- Growth phase: Optimum multiplication
- Stationary phase: Nutrients decrease (can remain here for a while)
- Death: Non nutrients
What bacteria causes Lyme disease?
Borrella burgdorferi
What is in tears which provides a barrier to infection?
Lysozyme
Microbe free areas? (7)
Blood, Urine, CSF
Muscles, glands, inner ear, brain
What are the three types of pathogen?
Overt/Strict: Disease causing
Opportunistic: Causes disease when they end up where they’re not supposed to be
Faculative: Survives in host normally
What is the role of virulence factors?
Facilitate colonisation, growth, spread and immune evasion
Give 5 examples of virulence factors and their roles
Adhesions: Fimbriae, pili, membrane proteins Flagella: Mobility and penetrate mucin Capsule: Prevents phagocytosis Type 3 secreted molecules Toxins
What 3 diseases does streptococcus pneumoniae cause?
Pneumonia, Sepsis, Meningitis
Give 5 virulence factors of streptococcus pneumoniae
Capsule Surface adhesions Secretory IgA protease (cleaves IgA) Neuraminase Spore formation
Endotoxin: Which bacteria release it? How does it react to heat? What does it cause? (2) Toxicity?
Gram negative
Heat stable
Fever, D+V
Weak toxicity
Exotoxin: Which bacteria release it? How does it react to heat? What does it target? Toxicity? Intracellular or extracellular?
Gram positive and negative Heat fluctuation Specific targets High toxicity Extracellular
Define toxoid
Inactivated toxin used as a vaccine
Give 2 examples of enterotoxins
What do they cause
Cholera and E.coli
Permeability change and D+V