This occurs when the metabolic needs of cells are not being met because of inadequate blood flow. In effect,there is a reduction in circulatory blood volume in blood pressure and in cardiac output. This causes tissue hypoxia,an inadequate supply of nutrients and the accumulation of waste products.
TYPES OF SHOCK.
1.HYPOVOLAEMIC SHOCK.
This occurs when the blood volume is reduced. Cardiac output may fall because of low blood volume and hence low venous return,as a result of different situations:
A)severe haemorrage- whole blood is lost.
B)extensive burns- serum is lost
C)severe vomiting and dirrhoea- water and electrolyte are lost
2)CARDIOGENIC SHOCK.
This occurs in acute heart disease when the damaged heart muscle cannot maintain an adequate cardiac output eg in myocardial infarction.
3)SEPTIC SHOCK
This is caused by severe infections in which bacterial toxins are released into the circulation. They trigger a massive inflammatory and immune response and many powerful mediators are released.It can cause multiple organ damage including hypotension because of widespread vasodilation,depression of myocardial contractility,poor tissue perfusion and necrosis
4)NEUROGENIC SHOCK
This causes sudden acute pain,severe emotional experience,spinal anaesthesia and spinal cord damage. They interfere with normal nervous control of blood vessel diameter,leading to hypotension.
5)ANAPHYLACTIC SHOCK
This is a severe allergic response that may be triggered in sensitive individuals by substances like peanuts,penicillin or latex rubber. Vasodilation,provoked by systemic release of mediators eg histamine and bradykinin, causes venous pooling and hypotension. Severe bronchoconstriction leads to respiratory difficulty and hypoxia.
