HYPERAEMIA – When vessels of the microcirculation contain more blood than normal

• Active hyperaemia – Blood flow is increased (this is an active process, where arteriolar dilation leads to increased blood flow)
• Passive hyperaemia  =  Congestion (See below)

CONGESTION – This is synonymous with PASSIVE HYPERAEMIA. Congestion is a passive process in which there is reduced outflow of blood from a tissue.

OEDEMA - An excessive extravascular accumulation of fluid, within the interstitial tissues.

Oedema fluid may be transudative or exudative. Refer to the mindmap for more explanation.

Note: Fluid accumulations within body cavities are named according to the site, eg. Hydrothorax or pleural effusion (within pleural cavity).

HAEMORRHAGE – The extravasation of blood into the extravascular space.

Haemorrhage can be traumatic or spontaneous, the latter usually due to vessel or coagulation abnormalities.

SHOCK – A state of inadequate perfusion of cells and tissues, leading to reversible hypoxic injury and, if severe or prolonged enough, to irreversible cell and organ injury and death

There are several types of shock:

• Hypovolemic shock – Due to markedly reduced volume eg. haemorrhage, severe burns, vomiting & diarrhea.
• Cardiogenic shock – Due to pump failure.
• Distributive shock – Due to generalised vasodilatation eg. septic shock, anaphylactic shock, neurogenic shock.