Histopathology Flashcards
What are the most commonly run chemical pathology tests?
- Electrolytes (esp. Na + K)
- Urea & Creatinine
- Calcium & Phosphate
- Liver Function (LFTs = liver enzyme measurements)
- Hormone Assays
- Glucose
Anticoagulants are added to samples - what is the purpose of the following:
(a) EDTA
(b) Fluoride Oxalate
(a) EDTA = potassium = maintains cells
(b) Fluoride Oxalate = poison
What 5 qualities should all diagnostic tests have?
- Specificity
- Sensitivity
- Rapid
- Non-invasive
- Cost effective
What can virological tests detect?
- Inefctious virus
- Viral protein componenets (i.e. antigens)
- Viral genetic components
- Host response
List some of the potential sample sites for virological sampling
- Throat swap, NPA, broncheolar lavage etc. = resp. viruses
- Stool = GI viruses
- Urine = UT viruses
- CSF = viruses capable of crossing BBB (eg: herpes)
- Blood = serology (i.e. antibody detection)
- Saliva = serology
Briefly outline what the following techniques are used for (in reference to diagnostic virology)
- EM
- Immunofluorescence
- Serology
- Quantification Assays
- EM
- Visualisation of viral structures
- Immunofluorescence
- Detection of viral antigens
- Serology
- Detection of antibodies
- Quantification Assays
- Measuring viral load
With regards to diagnostic microbiology, what is the optimal time for the collection of specimen?
In the acute phase of illness
Before antimicrobials have been started
Give an example of a sterile and non-sterile culture site for diagnostic microbiology
Sterile = blood or CSF
Non-sterile = skin or throat swab
Briefly outline what the following techniques are used for (in reference to diagnostic microbiology)
- Microscopy
- Serology
- PCR
- Microscopy
- Gram-staining, identification of bacteria
- Serology
- Monitor Ab response, identification of bacteria
- PCR
- Used to detect MRSA
Define the role of a cytopathologist
Cytopathologists make diagnoses on cells
Define the role of a histopathologist
Histopathologists make diagnoses based on tissue
List some of the uses of clinical immunology
- Immunodeficiency
- Malignancy
- Auto-immunity
- Inflammation
- Tissue typing
- Histopathology
- Diagnostics
Define inflammation
Inflammation is a provoke response to tissue injury
- It is a complex reaction of vascularised connective tissue to injury
- It is non-specific
- Aim = destory, dilute or “ward off” injurous angents
Briefly outline the main difference between acute and chronic inflammation
Acute = short duration, rapid response, usually physiological
Chromic = long duration, slow response (often follwos acute inflammation), usually pathological
What are the 5 clinical signs of acute inflammation?
- Rubour - redness
- Tumour - swelling
- Calor - heat
- Dolor - pain
- Functio laesa - loss of function
What are some potential causes of acute inflammation?
- Physical agents (eg: trauma)
- Chemical agents (eg: poisons)
- Bacterial agents
- Immunological reactions
- Hypoxia
What are the effects of acute inflammation?
- Fever
- Increased pulse + BP
- Increased temperature + chills
- Anorexia
- Leukocytosis
- Protein production (liver)
What are the outcomes of acute inflammation?
- Complete resolution
- Healing with scar formation
- Chronic inflammation
- Abcess formation
What three processes are invovled in acute inflammation?
- Vascular Changes
- Cellular Changes
- Chemical Mediators
Outline the three major vascular changes that occur with acute inflammation
- Changes in vascular calibre
- Brief vasoconstriction (minimise spread)
- Prolonged vasodilation (increase blood flow to combat invaders)
- Physical = rubor + calor
- Changes in vascular permeability
- Increased permeability (plasma proteins + WBCs)
- Changes in blood flow
- Increased blood flow (accomodates emigraton of WBCs)
What is the difference between (a) exudate and (b) transudate?
Exudate
- Inflammatory extra-vascular fluid
- Protein rich
- Result of inflammation
Transudate
- Ultra-filtrate of blood
- Low [protein]
- Result of hydrostatic or osmotic imbalance
Extravasation of luekocytes (i.e. cellular events) is a co-ordinated event in acute inflammation - what steps are involved?
-
Margination
- WBCs come out of central axial column to the periphery
- WBCs align along the endothelial surface
-
Adhesion
- Activation of endothelial cells upreguates adhesion proteins
- Adhesion proteins enable WBCs to leave the vessel lumen
- Rolling
-
Diapediesis
- Leukocytes pierce the basement membrane and degrade it
-
Chemotaxis
- Locomotion oriented along a chemical gradient
- Assisted by chemo-attractants
-
Phagocytosis
- Recongition + Attachment
- Engulfment
- Killing + Degradation
What 4 families of adhesion proteins are involved in acute inflammation?
- Selectins
- Immunoglobulins
- Integrins
- Mucin-like glycoproteins
Outline the role of cytokines during the acute inflammatory process
Adhesin proteins are partially under the control of cytokines - they help to increase their affinity for endothelial binding sites, enabling stable binding between the endothelium and the WBCs (via the adhesin proteins)
What is the difference between a plasma-derived and cell-derived chemical mediator of acute inflammation?
Plasma-derived = synthesised in pre-cursor form, must be activate, short-lived
Cell-derived = synthesised de novo in active form, short-lived
Name and describe the two major vasoactive amines
Histamine
- Cell-derived
- Widely distributed
- Released in response to trauma and immune reactions
- Causes dilation of aterioles
Serotonin
- Cell-derived
- Present in platelets
- Simiar action to histamine
How is acute inflammation terminated?
Eradication of offending agent leads to the discontinuation of the inflammatory response
The process is aided by the short-lived nature of cells and chemicals invovled in inflammation
Define Chronic Inflammation
Chronic inflammation = prolonged inflammation in which active inflammation, tissue destruction + attempts at repair are occuring simultaneous
Describe the two scenarios which can potentially result in chronic inflammation
- Following acute inflammation
- Low-grade, long-standing inflammatory resposne
List some of the potential causes of chronic inflammation
- Persistent infection (eg: TB)
- Prolonged exposure to toxins
- Autoimmunity
Name three histological features of chronic inflammation
- Infiltration by mononuclear cells (i.e. macrophages, lymphocytes, plasma cells)
- Tissue destruction
- Attempts at healing (i.e. connective tissue laying and fibrosis)
Name the 4 cell types invovled in chronic inflammation
- Macrophages
- Lymphocytes
- Eosinophils
- Mast Cells