S1L2 - CVS Anatomy And Imaging/ Haemodynamics Flashcards
Where does deoxygenated blood from the upper body go?
Drains into the superior vena cava
Where does the deoxygenated blood from the lower body go?
Drains into the inferior vena cava
What tool can be used in imaging to gain a clearer image of arteries?
Contrast agents
What is the diacritic notch?
A dip in the aortic pressure just after systole due to the aortic valve closing.
What are the first branches from the ascending aorta?
Right and left coronary arteries
What are the three major branches produced at the arch of the aorta?
Firstly brachiocephalic artery, then the left common carotid artery, then the left subclavian artery.
What does the brachiocephalic artery bifurcate into?
The right common carotid artery and the right subclavian artery.
What is the typical cardiac output of a 70kg man?
5L
How do you work out cardiac output?
Heart rate x stroke volume
What is the range for a healthy resting heart rate?
60 to 90 bpm
What are the 3 layers of the heart wall?
Epicardium - serous membrane, smooth outer surface of the heart
Myocardium - cardiac muscle cells
Endocardium - smooth inner surface of heart chambers
What are the pectinate muscles?
Muscular ridges in right atrial walls.
What are the trabeculae carnae?
Muscular ridges and columns on inside of ventricles.
What is a transoesophageal echocardiography?
An ultrasound of the heart. Uses sound waves.
How are coronary arteries usually imaged?
By CT angiography
What are the main 2 components of blood?
Plasma (fluid containing proteins and electrolytes)
Cells
What affect do cells and proteins have on the viscosity of blood?
The greater the protein and cell content of blood, the greater the viscosity
What is laminar flow?
Blood flow that is smooth and not interrupted, adjacent layers of fluid slide over each other. Usually quiet
What is turbulent flow?
Disorganised flow. Produces a noise or bruit.
Where should blood pressure readings be taken?
At the level of the heart.
What is the mediastinum?
The intervening region in the thoracic cavity between the right and left pleural cavities which are occupied by the lungs. The heart sits in the middle of the mediastinum.
What sits in the middle mediastinum?
Pericardial sac containing the heart and its blood vessels, and the roots of the aorta, superior and inferior vena cava and the pulmonary vessels.
What do the phrenic nerves supply?
Diaphragm and pericardium .
What nerve roots are in the phrenic nerve?
C3 C4 C5 keeps the diaphragm alive
Where does the apex of the of the heart normally sit?
sits in the 5th intercostal space at the mid clavicular line on the left
What forms the majority of the anterior surface of the heart in situ?
The right ventricle
What is the difference between serum and plasma?
Serum is plasma without clotting factors.
Serum is collected from clotted blood.
What does the measurement of CRP (c reactive protein) indicate?
Used as an indicator of inflammation
What impacts the movement of blood throughout the body?
The metabolic demands.
How does blood move fastest in arteries?
Moves fastest in lamina flow as energy is conserved. Highest velocity is the blood in the centre of the vessel during laminar flow.
Where does turbulent flow in arteries occur?
Stenosis arteries, changing direction of vessels.
What is flow?
The volume transferred per unit time (L/min)
What is pressure?
Force per unit area (mmHg)
How does blood pressure vary in a healthy individual?
Both blood pressure and flow pulsate. The blood pressure is highest in arteries and decreases substantially in veins
How can flow be seen as a factor of pressure?
Flow is the ease with which blood can flow under a certain pressure. Flow = K ( change in P) Or Flow = change in P / R K is conductance
What is conductance?
A measure of ease of flow
What is resistance?
Resistance is a measure of the difficulty of flow.
What has to happen to change blood supply to an organ?
Change in resistance
Or
Change in pressure
What changeable factor impacts the resistance of a vessel?
Vessel diameter
What vessels contribute greatest component of total peripheral resistance?
Smallest arteries and arterioles due to big decrease in diameter.
What is velocity?
The distance fluid moves in a given time
How is flow related to velocity?
F =V x A
A is the cross sectional area of a vessel.
Where is velocity of blood slowest in the CVS?
In capillaries. This allows plenty of time for diffusion of substances from blood to cells.
How is lower velocity achieved in capillaries?
Much larger total cross sectional area.
What is pulse pressure?
Pulse pressure = systolic blood pressure - diastolic blood pressure
How is mean arterial pressure calculated?
MAP = DBP + (SBP-DBP/3)
What is the pulse?
A shock wave that drives slightly before the blood itself.
How can be increase pulse pressure
Bradycardia - heart block, allows for a larger SV
Vasodilation - decreases the peripheral resistance
Elite athletes - systolic increased, diastolic decrease.
What is the name of the sounds heard when measuring blood pressure?
Korotkoff sounds.
What does auscultation mean?
The action of listening with a stethoscope
Why is blood pressure below the level of the heart greater?
Gravity
What is postural hypotension?
Dizziness upon standing. Occurs because of decreased stroke volume an transient arterial hypotension.
What can be heard and felt over a stenosed artery?
Turbulence
Can feel a thrill
Can hear bruit
How is blood flow increased to tissues?
By vasodilation, increasing the cross sectional area of vessels.
What are the changes in flow and velocity through a stenosed vessel?
Flow is decreased after the stenosis, velocity is increased.
What has the greatest impact on the resistance within a vessel?
Vasodilation
What does the visceral pericardium adhere to?
Ther Inner serous layer of the pericardium adheres to the external wall of the heart
What are the first arteries to arise from the aorta?
Left and right coronary arteries
When does blood enter the coronary arteries?
During diastole, when the backflow of blood from the aorta fills the aortic sinuses behind the left and right flaps of the aortic valve.
What are Kortokoff sounds?
Sounds heard when taking a blood pressure reading when the artery is partially occluded.
What layers form if unclotted whole blood is centrifuged?
Plasma
Buffs coat - white cells
Red blood cells.
What layers form if clotted blood is centrifuged?
Serum
Clot
When might we see changes in whole blood viscosity?
Polycythaemia
Thrombocythaemia
Leukaemia
What can cause plasma viscosity changes?
Inflammation
Acute illnesses
What causes turbulent flow?
Stenosis of a vessel
This could be caused by compression of the vessel or atheroma / atherosclerotic build up.
Describe the relationship between flow and perfusion pressure ina vessel with laminar flow
Both flow and perfusion pressure are directly proportional. Laminar flow is a linear line, demonstrating an increase in flow with an increase in perfusion pressure.
Why is turbulent flow not linear on a graph of flow/perfusion pressure?
Due to disruption of the blood slowing the flow past the stenosis. The flow becomes disrupted after the critical reynold number is exceeded
What are the units of blood pressure?
MmHg
What is Darcys law?
Flow = change in pressure / resistance
What is the biggest determinant of resistance?
Diameter of a vessel.
Where is the biggest change in pressure across a vessel class?
Arterioles - reduce the systemic blood pressure due the increase in total peripheral resistance.
What anatomical feature of the heart demonstrates the greater increase in systemic circulation than pulmonary circulation?
The thickness of the left ventricle is much thicker than the right ventricle to increase the reassure at which the blood is pumped into the systemic circulation.
How is flow related to the velocity of blood?
Flow = velocity x cross sectional area
What is occurring at end diastolic pressure?
When the ventricles are filling with blood.
What is the cardiac output?
The total flow of blood in one given systole.
How do we calculate the mean arterial pressure?
Mean arterial pressure = cardiac output x total peripheral resistance
What can cause changes in pulse pressure?
Haemorrhage - drop in diastolic pressure
Age - reduced compliance due to atherosclerosis -> increased systolic pressure
What causes a bounding pulse?
An increase in the pulse pressure (DBP -SBP)
This could be caused by : bradycardia, vasodilation, elite athletes
What is bruit?
The sound heard from turbulent flow
What is thrill?
The sensation felt by turbulent flow.
What is postural hypertension?
Dizziness upon standing. Caused by pooling of blood in the venous system below the level of the heart due to the effect of gravity. This reduced stroke volume and there is transient arterial hypotension.
