Circulation Flashcards
How does the inside of a normal artery look like?
Endothelial cells on the basal lamina which are smooth muscle cells
Surrounded by interstitial collagen fibres around it.
What is serum?
Blood plasma without clotting factors
Where are clotting factors made?
Mainly produced by the liver
Also produced by endothelial cells
What is an amplification system?
It causes fibrin to increase and TF to reduce
What is an overview of an amplification system?
Prothrombin into thrombin
Which causes fibrinogen into fibrin
What triggers the clotting cascade?
Exposure of interstitial collagen and exposure of TF (tissue factors)
What are the 2 mechanisms of clotting?
Thrombosis
Clotting
What does plasma consist of?
Water and numerous proteins
What is serum?
Plasma without clotting factors
How are clotting factors named?
Roman numerals
I.e clotting factor VIII
What does thrombin do?
Covert soluble firbrinogen into insoluble fibrin
What happens in the clotting cascade?
Damage causes the release of tissue factors from smooth muscle
This promotes change of prothothrombin to thrombin which causes fibrinogen to become fibrin
What triggers the release of tissue factors?
Exposure of interstitial collagen to the serum due to trauma
How does the clotting cascade keep going?
Most clotting factors are serine proteases
An activated serine molecule acts as a precursor for the next clotting factor
Where are platelets made?
Bone marrow from megakaryocytes
Why is division in megakaryocytes?
Nuclear division of the cell therefore its a huge cell with many nuclei
Platelets bud off the cytoplasm
How do platelets cause clotting?
Platelets adhere together to bridge close the gap in vessels by becoming sticky when activated
What are the types of coagulation?
Thrombus formation
Clot formation
What is thrombus formation?
Occurs when blood is flowing
Platelets and fibrin combine to form a platelet thrombus on the blood vessel wall
What is a clot formation?
Network of fibrin and red blood cells formed. By exposure to collagen and stagnant blood
What is haemostasis?
Stopping bleeding
Why does vasoconstriction happen in injury?
It decrease the size of vessels consequently decreases amount of blood loss
Why do clots form?
Prevent excessive bleeding
Allows for formation of a thrombus
What is granulation tissue?
When new vessels grow into the wound/clot to keep it oxygenated
The new vesssel is called granulation tissue
How is a thrombus removed?
Plasminogen in the blood gets converted to plasmin
This cuts fibrin into small fragments
What is thrombolysis?
Removing of a thrombus by removing fibrin
What is the fibrinolytic system?
A system which removes fibrin and stops thrombin from propagating which is in balance with the clotting system
When is thrombosis and clotting normal?
Stop bleeding during metabolism
Wound healing
What are the 3 main causes of thrombosis?
Changes of the internal surface of a vessel
Change in blood flow pattern
Change in blood constituents
What is Virchows triad?
- Changes in the intimal surface of a vessel
- Changes in the pattern of blood flow
- Changes in the blood constituents
What is an amplification system?
Clotting factors activates other clotting factors to enhance the clotting system
When is thrombosis normal?
Cut
When is thrombosis abnormal
No cut or injury
How does smoking affect thrombosis?
It makes platelets more sticky
Hence a thrombosis is likely to occur
What is atheroma?
Disease of coronary artery which results in build up of lipid under intimal surface. (In between outermost layers of artery)
How does atheroma cause problems with thrombosis?
Causes slowed blood flow hence increase chances of clotting
Or the lipid ruptures the artery which exposes the collagen to platelets and fibrin causing thrombosis
This also causes blood to stop flowing and develop a clot
What are the lines of Zahn?
What is ischaemia?
Poor blood flow
How does ischaemia cause hypoxia?
Poor blood flow means less oxygen in tissues
What is an infarct?
Localised area of dead tissue due to hypoxia killing cells
Ischaemic necrosis
What is an embolism?
Mass of material in blood vessels which can block lumens
Typically clots or thrombi
What is a thromboembolism?
Thrombi or clot which embolises
How can a pulmonary embolism arise?
Slow flow in leg vein causes clot to form. Clot travels through the vein through the heart and into the lungs
Why must you check your syringe for air bubbles.
Can cause an air embolism
What is circulatory shock?
Bad circulatory failure as organs can’t get sufficient diffused blood.
What is normal bp?
120/80
Much lower venous pressure
When is it shock?
Low bp
Fast pulse
Explain what happens in shock?
How does septicaemia chase septic shock?
Infection in blood causes vasodilation so blood begins to pool and doesn’t spread around the body
What are the main complications of shock?
Decreased perfusion to organs like kidneys or brain.
What are the 3 main causes of circulatory shock?
Hypovolaemic
Septic
Cardiogenic
What surrounds the basal lamina of vessels?
Elastic tissue
How is blood pressure maintained?
Enough blood in the system
Smooth muscles gave enough tone
Heart pumping blood
What is hypovolaemic shock?
Haemorrhage
Less systemic blood
Hence decrease pressure
Vessels collapse
Blood can’t enter heart
Now blood can’t go around body
Systemic blood pressure drops
What do cartoid sinuses do?
Sense lower systemic pressure
Upregulates sympathetic system
Rapid breathing and fast pulse to try and increase bp
What happens in Cardiogenic shock?
Heart can’t pump blood as heart is failing
Blood pressure drops
Pulse increases
What happens in septic shock?
Too much Vasodilation occurs as there’s an infection in blood
Too much dilation not enough blood in circulation
What happens in severe septic shock?
Muscles in heart lose their tone as they don’t get enough oxygen and nutrients and leads to wastage or acidosis
Heart rate is slowed hence bradycardia
What pressure drops in septic shock?
Arterial as vasodilation causes it
What pressure drops in hypovalemic ?
Venous
What are complications of shock?
Brain injury as decreased perfusion to brain (MOST IMP AND HAPPENS FISRT ISH)
Decreased perfusion of kidney
