Pathology Flashcards
What are the main differences between hyperaemia and congestion
Hyperaemia
- Flushed, hot, red (after running, embarrassed)
- Arteriolar dilatation and increased blood flow
- Active process
Congestion
- Cardiac failure, DVT
- Cyanotic (blue-red) (oxygen depletion)
- Obstructed venous outflow +/- lymphatic -
drainage
- Passive process
what is the difference between transudate and exudate oedema
Exudate = fluid + proteins +/- debris
usually inflammatory
Transudate = mostly just fluid, usually non-inflammatory
What are the two causes of transudative oedema
- Increased capillary hydrostatic pressure
- decreased plasma osmotic pressure
What is the defition of haemorrhage?
loss of blood from vasculature
What are some different types of haemorrhages?
haemotoma, petechiae and pupura, ecchymoses
Describe the features of a heamotoma
○ Collected blood in tissues or a body cavity
§ Haemothorax = lung area
§ Hemarthrosis = joint
§ Hemoperitoneum = body cavity
○ Small or large
○ Large can be life-threatening due to exsanguination (draining, severe blood draining/loss) and hypovolaemia (loses fluid)
Normal part of healing especially in bone fracture
Describe the features of petechiae and pupura
○ Small bleeds into skin or mucous membranes
§ 1-2mm = petechiae
§ 3-5mm = purpura
○ Causes:
§ Defective and low platelets (thrombocytopaenia)
§ Vitamin C deficiency
§ Infection
Vasculitis
Describe the features of petechiae and pupura
○ Small bleeds into skin or mucous membranes
§ 1-2mm = petechiae
§ 3-5mm = purpura
○ Causes:
§ Defective and low platelets (thrombocytopaenia)
§ Vitamin C deficiency
§ Infection
- Vasculitis
Describe the features of Ecchymoses
○ Bruises or contusions
○ 2-5cm
○ Bleeding into subcutaneous tissues
○ Changes of colour due to breakdown of
haemoglobin to bilirubin and haemosiderin
What are the three features of Virchows triad?
○ Endothelial injury (vessel wall problem - intrinsic pathway)
○ Abnormal blood flow
○ Hypercoagulability (blood problem - congenital or acquire condition = increased coagulation)
Define thrombosis and what vessels does it affect?
The formation of clots within the cardiovascular system
Arterial/cardiac: sites of vessel injury or turbulence
Venous: sites of stasis (pooling of blood in limbs)
Describe the endothelial injury point of virchows triad
Endothelial exposure encourages platelet adhesion and promotes inappropriate coagulation and clot formation
○ Hypertension
○ Vasculitis
○ Toxins (cigarette)
○ Hypercholesterolaemia
○ Radiation injury
Describe the flow problem point of virchows triad
Abnormal cardiac function reduced laminar flow of blood: areas of turbulence and stasis create opportunities for platelet aggregation and clot formation
○ Atrial fibrillation
○ Acute myocardial infarction
○ Valvular dysfunction
Describe the blood problem point of virchows triad
Dysfunctions of coagulation cascade factors promote inappropriate clot formation
○ Inherited conditions (primary)
§ Factor V Leiden mutation
○ Induced (secondary)
§ Pregnancy
§ Oral contraceptive pill
§ Procoagulant tumours
§ Smoking
§ Obesity
What are some examples of thrombosis
DVT, AMI
Define embolism
A bolus of substance transported in the blood
Can be fatal when blocking blood flow to brain, heart or lungs
What are some causes of embolism
- Thrombus (thromboembolism, clot caused from blockage breaking off)
- Fat (fractures bone/surgery, bone marrow forced into blood vessel)
- Air (IV admin)
- Amniotic fluid
What is a systemic thromboembolism?
Arise within the heart
○ Can end up anywhere in the vasculature
○ Brain, lower limbs common
○ Pathology depends on size of thrombus and area affected by ischemia/infarction
What is a venous thromboembolism?
Usually arise in superficial or deep veins (DVT) of lower limbs
○ Risk factors: hypercoagulability, immobility, especially post-op
○ Can be asymptomatic
Pathology depends on size of thrombus and area affected by ischemia/infarction
What is a pulmonary embolism?
An embolus that blocks the pulmonary vasculature (in the lung)
○ Most are sub-clinical
○ Large are often fatal
○ Ischaemic pain (sharp)
○ Reduced lung function
-> respiratory distress
Define Ischaemia
- Reduced blood flow to tissues
- Results in pain and dysfunction
- Change of skin colour, temperature, pulses
Will eventually lead to infarction and tissue death (necrosis) if not fixed
Define infarction
- Blocked blood flow to tissues
- Results in downstream tissue death and necrosis
- Death of a certain part of tissue
What is the difference between pale infart and red infarct
Anaemic infarct - “Pale infarct
- Macroscopic definition, usually wedge-shaped and pale
- EG: heart, brain, spleen, kidney
- Usually one blood supply
Haemorrhagic infarct - “Red infarct”
- Macroscopic description
- Non-viable/dead tissue have weak intracellular integrity, which is easily bled into by any communicating source of blood
- Usually consequence of:
○ Tissues with dual/collateral blood supply (e.g. lung, liver)
○ Venous insufficiency
Reperfusion into dead (infarcted)/dying (ischaemic) tissue
What are the common causes of a red infarct/hemorrhagic infarct
○ Tissues with dual/collateral blood supply (e.g. lung, liver)
○ Venous insufficiency
○ Reperfusion into dead (infarcted)/dying (ischaemic) tissue
