Into to CVS and Haemodynamics Flashcards
What are the three layers of blood vessels and what are the differences in the layers in veins compared to arteries?
The three layers are the:
Tunica adventia- this is a layer of connective tissue, a few cells, macrophages, mast cells, fibroblasts and the nerves/vessels that supply the vascular wall.
Tunica media- layers of smooth muscle
Tunica adventia- made up of endothelium and elastic Lamina
The veins three layers are thinner and less elastic than arterial walls, the veins are not exposed to the same amount of pressure, they only have one layer of smooth muscle cells. The walls of veins have valves attached. Also a skeletal muscle pump function in the venous system helps propel blood back to the heart by creating a vacuum due to pressure differences between muscle contractions.
What is the exception artery which has valves?
The pulmonary artery which carries deoxygenated blood from the heart to the lungs.
What is responsible for the rise in aortic pressure from diastolic to systolic?
Determined by the compliance of the aorta (The ability to expand) and the ventricular stroke volume (Amount of blood pumped out of the ventricle).
What is the difference in systolic and diastolic blood pressures?
Systolic blood pressure is the blood pressure when the heart is contacting, it is specifically the maximum arterial pressure during contraction of the left ventricle of the heart, the time at which ventricular contraction is called systole.
Diastolic blood pressure is the phase of blood circulation in which the hearts pumping chambers are being filled with blood, during this phase the ventricles are at their most relaxed and the pressure against the walls of the arteries is at its lowest.
What are the layers of the heart?
Epicardium- Serous membrane; smooth outer surface of heart
Myocardium- Made up of simple squamous epithelium, loose CT and adipose tissue
Endocardium- Smooth inner surface of heart chambers
Pectinate muscles- muscular ridges in right atrial wall
Trabeculae carnae- muscular ridges and columns on inside wall of ventricles
What is haemodynamics?
The study of the movement of blood and the forces concerned there.
What is plasma and what is serum?
Plasma is the fluid from the blood in which elements (Red blood cells) are suspended
Serum is the fluid collected from clotted blood, it is the plasma- clotting factors (in particular fibrinogen).
What happens with a marked increase in plasma viscosity?
An increase in plasma viscosity can lead to increased whole blood viscosity and slugging of blood in peripheries. The commonest cause is multiple myeloma (tumour of plasma cells normally found in the bone marrow). Increase in RBC, platelets, WBC can lead to an increased whole blood viscosity and sludging of blood in the peripheries.
What are the reasons for plasma viscosity changes?
Can result from raised levels of acute plasma proteins eg: fibrinogen/complement factors/C-reactive protein. Acute phase proteins increase in response to inflammation. Therefore minor changes in plasma viscosity can be used to measure the inflammatory response.
Although plasma viscosity (resistance to flow) can be a measure of acute inflammation, what is more commonly used to measure acute inflammation?
Measuring the C-reactive protein is more commonly used!
What is a characteristic of blood flow?
Blood flow is called LAMINAR flow, it is when blood flows in streamlines with each layer of blood remaining the same distance from the wall, when laminar flow occurs the velocity of blood in the centre of the vessel is greater than that toward outer edge- parabolic profile.
What is the difference between laminar and turbulent blood flow?
Laminar flow when the blood is flowing streamline with each layer of blood remaining the same distance from the wall.Turbulent flow is when the blood is flowing in all directions in the vessel and continually mixing within the vessel.
What are the causes of turbulent flow?
Turbulent flow is caused by the rate of blood flow becoming too great, when it passes by an obstruction in the vessel, when it makes a sharp turn, when it passes over a rough surface, increased resistance to blood flow ie: a stenosis/peripheral resistance.
What is meant by arterial/pulse pressure?
Pulse pressure is basically the difference between the diastolic and systolic pressures. (Peak systolic pressure- end diastolic pressure), which because we measure BP with a SPHYGMOMANOMETER means it is 120-80mmHg= 40mmHg
Arterial pressure can be calculated by diastolic pressure + 1/3 pulse pressure.
What does it mean if the arterial pressure is below 70mmHg?
It means that arterial perfusion is impaired!
