Cardiovascular Pathophysiology Flashcards
Define pathophysiology
Deranged function in an individual or organ that is due to disease.
What is a pathophysiological alteration?
A change in function as distinguished from a structural defect.
What is aetiology?
The study of causes. Deals with the origin of disease, the factors which produce or predispose towards a certain disease or disorder.
What is epidemiology?
The study of population in order to determine the frequency and distribution of disease and measure of risks.
What is histopathology?
The study of microscopic anatomical changes found in diseased tissue.
What is cytopathology?
The study of disease changes within individual cells or cell types.
What is the no.1 disease of death globally?
Cardiovascular diseases
What factors is cardiovascular function based on?
- Cardiac pumping ability
- Integrity of vasculature
- Blood volume/ composition
What factors of cardiac pumping ability affect cardiovascular function?
- Pace making electrical signal.
- Force of contraction.
- Muscle strength.
What factors of integrity of vasculature affect cardiovascular function?
- Presence of blockage.
- Muscle tone/ structural integrity.
- Pressure drop needed to move blood to and through capillary beds.
What factors of blood volume/composition affect cardiovascular function?
- Water and electrolyte balances.
- Lipid composition
What are the 3 layers of the blood vessels?
Tunica intima, tunica media, tunica externa/adventitia.
What is the tunica intima in terms of blood vessels?
Endothelium, basement membrane and internal elastic lamina.
Innermost layer - lines lumen and is the only layer in contact with the blood.
What is the tunica media in terms of blood vessels?
Middle layer. Elastic fibres and smooth muscle is orientated around the lumen. This layer can stretch and in some circumstance it contract.
What is the tunica external/ adventitia in terms of blood vessels?
The outermost layer is composed of elastic tissue and collagen.
Describe the blood vessel structure of the aorta? What are the benefits of this?
The aorta has a lot of elastic tissue in the Tunica Media. This allows stretch of the wall to allow the pulse to pass by.
Describe the blood vessel structure in veins. and why this is beneficial.
Thin Tunica Media with a lot of collagen and elastic fibres. The Tunica Adventitia is wide with longitudinal smooth muscle to aid retuning blood to the heart.
Wide lumen carries blood at a low pressure
Describe the blood vessel structure in arteries and why this is beneficial.
They have a narrow lumen and strong walls to carry blood away from. the heart at high pressure.
Describe the blood vessel structure of capillaries.
Only 1 layer of cells in the endothelium and basement membrane.
Huge surface area for fast exchange.
What parts of the body promote venous return ?
Legs and diaphragm
What is hypertension?
High blood pressure
What is meant by a ‘primary’ pre-disposing factor to hypertension?
No clear known cause
What is meant by a ‘secondary’ pre-disposing factor to hypertension?
Hypertension as a result of another condition.
What blood pressure classes as hypertension?
A blood pressure greater than 140 over 90 mmHg.
What factors control blood pressure?
- Blood volume
- Effectiveness of heart as a pump for cardiac output
- Resistance of vasculature to blood flow
- Distribution of blood between arteries and veins
How is blood volume controlled?
Via fluid loss and fluid intake - regulated in the kidneys.
What controls the resistance of vasculature to blood flow?
Controlled via contraction and relaxation of smooth muscle in arteriole walls.
What controls the distribution of blood between arteries and veins?
Controlled via relaxation of smooth muscle in vein walls
What non-modifiable factors risk factors that affect high blood pressure?
Age
Gender
Genetics
What are the modifiable risk factors of high blood pressure?
High sodium intake
Excessive alcohol
Obesity
Stress
What is Atherosclerosis?
Patchy deposits of fatty material (atheroma’s) develop in the wall of medium and large arteries.
How quickly does atherosclerosis develop?
Slowly progressive and cumulative - over years and decades.
What is the net result of atherosclerosis?
Loss of elasticity, hardening and thickening of vessel walls and narrowing of the vessels lumen.
What are the non-modifiable risk factors of atherosclerosis?
Age
Gender
Genetics
What are the modifiable risk factors of atherosclerosis?
Hyperlipidaemia Hypertension Smoking Diabetes Some infections such as herpes.
What is hyperlipidaemia?
Excessive levels of lipids in the blood.
Outline the steps of atherosclerosis
- Endothelial lesion initiates the process.
- Endothelial dysfunction. Leukocytes and changes to vessel permeability.
- Smooth muscle cells migrate in
- Accumulation of lipid in fatty streak
How does Atherosclerosis affect blood vessel function?
- Atheroma’s build up on the vessel walls and cause them to weaken. This can trigger aneurysms.
- Plaque ruptures and promotes clotting - thrombosis or embolism.
- Plaque grows and blocks the artery - stenosis.
What is stenosis?
When a plaque grows and blocks the arteries.
How is the severity of atherosclerosis defined?
From no obstruction to total obstruction where no blood can move through the vessel at all.
What are the 2 main treatments of atherosclerosis ?
Angioplasty
Stenting
What is an angioplasty?
Insertion of a small balloon into the affected blood vessel to inflate it and squeeze out the plaque to re-open the lumen.
What is stenting?
A mechanism used to hold blood vessels open.
What is an aneurysm?
A blood filled dilation of a blood vessel.
What blood vessels are aneurysms most common in?
The aorta and the circle of willis
What is the purpose of the circle of willis?
Used to maintain a constant blood supply to areas of the brain.
Why do aneurysms happen in the aorta?
Blood vessels where the pressure is highest. Most force acting outwards on the vessel wall
Why do aneurysms happen in the circle of willis?
It is a complex structure with a lot of junctions. These junction points are weak in vessel walls and are susceptible to aneurysms.
What part of an aneurysm causes damage?
Bursting of the aneurysm
How does bursting of the aneurysm cause damage?
It causes a drop in blood pressure and reduced tissue perfusion. If severe, it may cause death.
Why does hypertension promote aneurysms?
Hypertension promotes aneurysms because the high blood pressure and atherosclerosis weakens the vessel walls and makes them more susceptible to aneurysms.
What is blood stasis?
The blood is not flowing or circulating as optimally as it could to all parts of the body.
What factors accelerate aneurysms forming?
Local haemodynamic factors, intrinsic factors, systemic hypertension accelerate development.
What is LaPlace’s Law? And how does this explain aneurysms?
Arterial wall tension proportional to pressure times radius of arterial conduit. Therefore a positive feedback loop - as diameter increases, wall tension increases, which promotes further diameter increase. This continues until an aneurysm ruptures.
What is a vaso vasorum?
Aneurysm causes ischaemia of vessel wall which leads to further expansion and therefore further damage.
What is ischaemia?
Blood flow is restricted to a part of the body.
What does Virchow’s Triad explain?
The way in which blood clots may form in the blood.
What is Virchow’s triangle and what does it include?
It describes the way that blood clots form in the blood
- Vessel wall injury/ changes.
- Changes in blood flow
- Change in blood constituents
What are embolisms?
Moving blockages of the vasculature
Name some different types of embolisms?
Thromboembolisms. Fat embolisms. Air embolisms. Gas embolisms. Septic embolisms. Tissue embolisms.
Name some possible consequences of thrombus/embolus formation.
Stroke Myocardial infarction Pulmonary embolism Deep vein thrombosis Ischaemic limb
If a thrombus forms in the veins, where is it likely to cause an embolism?
The thrombus is likely to move through the right side of the heart an cause pulmonary embolism.
What will happen if a thrombus forms in the veins and a patient also has septal defects ?
The thrombosis formed in the veins may travel to the left side of the heart and therefore travel anywhere in the body. This is called a paradoxical embolism.
What is a paradoxical embolism?
If a person forms an embolism in their veins and this therefore travels through the right side of the heart. However, the person has a septal defect and the thrombosis can move to the left side of the heart and therefore travel anywhere in the body.
If a thrombus forms in the left atrium, where can this travel?
Anywhere in the body.
What is myocardial infarction?
A heart attack
What causes a myocardial infarction?
When blood supply to the heart is blocked.
What are the risk factors of myocardial infarction?
Atherosclerotic coronary artery disease, angina, previous MI, stroke, smoking, alcohol, diabetes, high BP, high LDLs.
Where is referred pain I?
Chest pain radiating to the left arm caused by a heart attack.
What type of accident is a stroke?
Cerebrovascular