normal circulation + redistribution of blood

Rate of circulation determined by what

Metabolic situation

Normal circulation pressures - LV

>120 mmHg

Normal circulation pressures -Arteries

>120-60mmHG

Normal circulation pressures -Arterioles

>60-40mmHg

Normal circulation pressures -Capillaries

>40-20mmHg

Normal circulation pressures -Veins

>20-10mmHg

Normal circulation pressures -RA

>10-0mmHg

Which pressures are the same in arteries + veins

Tissue hydrostatic pressure, plasma colloidal osmotic pressure, tissue colloidal osmotic pressure

Which pressure is different in arteries + veins to cause pressure differences → filtration / absorption

Plasma hydrostatic pressure

Capillary bed purpose

Outflow of fluid (transudation) into extravascular spaces with O2 + nutrients

Classifications of disorders of circulation - redistribution of blood

Local increased vol of blood in tissue - active hyperaemia (arteries), passive hyperaemia (veins)

Reduced blood supply to tissue - ischaemia

Hyperaemia def

Increased vol of blood in tissue

Ischaemia def

Reduced blood supply to tissue

Classifications of disorders of circulation - Haemorrhage def

Loss of circulating blood vol

Classifications of disorders of circulation -Oedema def

Accumulation of extravascular fluid

Classifications of disorders of circulation - Disorders of haemostasis

Bleeding disorders, presence of solid masses/abnormal constituents, disseminated intravascular coagulation

Active hyperaemia - def + BV

Abnormal accumulation of arterial blood in arterioles/ arteriolar capillary bed

passive hyperaemia (congestion) - def + BV

Accumulation of blood in veins + venular capillary bed

Active hyperaemia - causes

Physiological, relaxation of arterial sphincters, dilation of arterioles

passvie hyperaemia - causes

Passive dilation of affected vessels

Passive hyperaemia - local causes

Obstruction of venous return from organ - organ misalignment, venous thrombosis/ embolism, compression (fibrosis, tumours, abscesses)

Passive hyperaemia local causes - how can organ misalignment cause venous obstruction

Thin walls + low pressure so affected by pressure

Passive hyperaemia local causes -Types of organ misalignment

Intussusception/ invagination, volvulus, torsion, twist, herniation with strangulation

Passive hyperaemia local causes -Types of organ misalignment Invagination features + how it causes issue

Soft tissues fold into each other → arteries not blocked → metabolism → no venous drainage → toxic accumulation

Passive hyperaemia local causes -Types of organ misalignment volvulus features + how it causes issue

Twist around mesenteric root → arteries not blocked → metabolism → no venous drainage → toxic accumulation

Passive hyperaemia local causes -Types of organ misalignment gastric dilation + volvulus features + how it causes issue

In deep chested dog breeds

Eating, aerophagia → spleen twisting with stomach

Passive hyperaemia local causes -Types of organ misalignment torsion features + how it causes issue

Rotation around long axis

Passive hyperaemia local causes -Types of organ misalignment twsit features + how it causes issue

Tubular structures twist around each other

Passive hyperaemia local causes -Types of organ misalignment herniation with strangulation features + how it causes issue

Exudation of organ from original position → strangulation

Consequences of organ misalignment

Haemorrhagic infarction → vein occlusion → persist acne of arterial blood supply → increased blood pressure → blood extravasation → necrosis

Active hyperaemia - tissue appearance

Bright red

Passive hyperaemia - tissue appearance

Dark blue/red, swollen

Passive vs active hyperaemia - which is local and acute only (not local + generalised, acute + chronic)

Active hyperaemia

Ischaemia def

Inadequate blood supply to tissue (complete/partial, local/general)

Ischaemia causes

Heart failure → general ischaemia

Artery obstruction → local ischaemia

Vein obstruction → stagnation, hypoxia, ischaemia

Artery Ischaemia tissue appearance

Pale

Causes of generalised passive hyperaemia

Heart failure, impeded venous return, increased pulmonary resistance

Causes of generalised passive hyperaemia- what can cause impeded venous return

Caval thrombosis, hydropericardium, exudative pericarditis

Causes of generalised passive hyperaemia- what can cause increased pulmonary resistance

Thoracic fluids, pulmonary fibrosis, pulmonary emphysema