1. Anatomy and Haemodynamics Flashcards
Capillaries are composed of…..
A single layer of endothelial cells surrounded by basal lamina
What do tissues that are more metabolically active have?
Higher capillary density
What is perfusion rate?
Rate of blood flow
Anatomically where does the apex of the heart lie?
At the left fifth intercostal space
What are the two layers of the pericardial sac?
Parietal and visceral layers
What condition does excessive fluid build-up in the pericardium lead to?
Cardiac tamponade
What is pericardiocentesis?
Removal of fluid from the pericardium
What two structures is the transverse pericardial sinus behind?
The pulmonary trunk of the pulmonary arteries and the ascending aorta
What is the oblique sinus?
The point posterior to the heart where the parietal and visceral layers of the pericardial sac are continuous with one another
What coronary artery often gets blocked in an MI
Anterior interventricular artery
What is the coronary sinus? Where does it drain into?
Main venous drainage of the heart, into the right atrium
What is blood serum?
Plasma minus clotting factors (fibrinogen)
What is the commonest cause of increased plasma viscosity and therefore slugging of blood in peripheries?
Multiple myeloma (cancer of plasma cells)
What can lead to increased whole blood viscosity?
Polycythaemia (inc RBC), thrombocythaemia (inc platelets), leukaemia (inc WBC), inc plasma viscosity
What is CRP?
C-reactive protein. Is an acute phase plasma protein, which increases in response to inflammation, so is used as a measure of inflammation. Can lead to minor changes in plasma viscosity.
What is laminar blood flow?
Blood flowing in streamlines, with each layer remaining the same distance from the wall. The velocity of blood in the centre is greatest.
What is turbulent flow?
Blood flowing in all directions and continually mixing
What causes turbulent flow?
Rate of blood flow becomes too great, passes by an obstruction in the vessel, makes a sharp turn, passes over a rough surface, increased resistance to blood flow
What is a thrill?
Vibration accompanying a cardiac or vascular murmur that can be palpated
What is a bruit?
An abnormal sound generated by turbulent flow of blood in an artery due to a stenosis
What causes the diacritic notch in a descending aorta pressure tracing?
Closure of the aortic valve
How do you calculate pulse pressure?
Systolic pressure-diastolic pressure
How do you calculate mean arterial pressure?
Diastolic pressure+1/3 pulse pressure
What does mean arterial pressure have to fall below for organ perfusion to be impaired?
70 mm Hg
