Blood Pressure And Volume Flashcards
What is the equation for arterial pressure?
= CO X TPR
What is the equation for cardiac output?
Stroke volume X Heart rate
What two things can you change to alter blood flow?
Vascular resistance
Perfusion pressure
What is perfusion pressure?
The pressure needed for blood to move through a vessel
What is autoregulation of blood pressure?
Blood flow matches metabolic demand
If outside a normal range of blood pressure, what mechanisms take over?
Extrinsic mechanisms
What are examples of intrinsic controls?
Metabolic auto regulation
Paracrine control
What are paracrine controls?
Locally acting cells produce chemicals which alter blood flow rate
What is hyperaemia? What are the two types?
Increased blood flow to tissues
Active hyperaemia and reactive hyperaemia
What chemicals can act as vasodilators during active hyperaemia?
CO2
Lactic Acid
Potassium ions
What chemicals act as vasoconstrictors during active hyperaemia?
Oxygen
What is ischaemia?
The restriction of blood supply to a tissue
What is infraction?
Tissue death due to inadequate blood supply
What is necrosis?
Death of cells due to disease,injury or failed blood supply
When does coronary blood flow mainly occur?
During diastole
What is afterload?
The pressure the heart is pumping against
What are examples of paracrine controls?
Nitric oxide - vasodilation
Local irritation e.g. histamine - vasodilation
Endothelial damage - vasoconstriction (prevent blood loss)
What are examples of extrinsic controls?
Baroreceptors in the aorta
RAAS -renin angio tensin aldosterone system
Hypothalamus gland
Pituitary gland
Where is the cardiovascular centre?
Medulla oblongata
How do baroreceptors monitor and control blood pressure?
Detect stretching in tissue
Rise in atrial pressure
Release action potentials to increase heart rate
How does the renin-angio tensin aldosterone system work to raise blood pressure?
Renin causes the liver to release angiotensin
Angiotensin released to lung
This and aldosterone from adrenal gland cause vasoconstriction
Anti diuretic hormone causes sodium and water retention in the kidney
What is the role of the kidneys in blood pressure?
Regulation - sets ‘normal’ value which can be reset
Relies on normal renal function
What is Starling’s Law?
Hydrostatic and oncotic pressures balance to determine the movement of fluid
