ICA Flashcards
Another name for acute inflammation
Neutrophil mediated inflammation
Another name for chronic inflammation
Macrophage/lymphocyte mediated inflammation
What are neutrophil polymorphs
White blood cells made in the bone marrow
They are called polymorphs because they have a polylobed nucleus
what is the lifespan of neutrophil polymorphs
very short lifespan, 2 or 3 days
What is the function of neutrophil polymorphs?
They phagocytose debris and bacteria and contain bags of enzymes (lysosomes) which can be used to kill and digest phagocytosed bacteria
Neutrophils are the first cells to arrive at the site of acute inflammation. They often die at the site of inflammation and are themselves phagocytosed by macrophages
What are macrophages?
Are also white blood cells
What is the lifespan of macrophages?
much longer lifespan than neutrophils, months to years.
Function of macrophages
also phagocytose debris and bacteria.
They also transport material to lymph nodes and may present the material to lymphocytes so a secondary immune reaction is induced.
What are lymphocytes?
What are the functions of lymphocytes?
Are long-lived cells (years) which produce chemicals involved in controlling inflammation and antibodies (from B lymphocyte plasma cells)
Lymphocytes are the immunological memory of the body ready to scale up defence against micro-organisms that have infected the body before
What are fibroblasts? And function?
Produce collagenous connective tissue in scarring following some types of inflammation
Sequence of acute inflammation
• injury or infection
• neutrophils arrive and phagocytose and release enzymes
• macrophages arrive and phagocytose
• either resolution with clearance of inflammation or por- gression to chronic inflammation
• examples of acute (neutrophil-mediated) inflammation
acute appendicitis, frostbite, Streptococcal sore throat
Sequence of chronic inflammation
either progression from acute inflammation or starts as ‘chronic’ inflammation such as infectious mononucleosis (thus better term is macrophage/lymphocyte-mediated inflammation)
• no or very few neutrophils
• macrophages and lymphocytes, then usually fibroblasts
• can resolve if no tissue damage (e.g. viral infection like glandular fever) but often ends up with repair and for- mation of scar tissue
What type of inflammation are granulomas involved in?
particular type of chronic inflammation with collections of macrophages/histiocytes surrounded by lymphocytes
When are granulomas significant?
due to myobacterial inefction such as TB or leprosy
• also seen in Crohn’s disease and sarcoidosis
• may be seen around foreign material in tissue
What prevents blood clots forming all the time?
- Laminar flow - cells travel in the centre of arterial vessels and don’t touch the sides
- Endothelial cells which line vessels are not ‘sticky’ when healthy.
What is thrombosis?
is the formation of a solid mass from blood constituents in an intact vessel in a living person
What are the stages of thrombosis?
The first stage of thrombosis is platelet aggregation. Platelets release chemicals when they aggregate which cause other platelets to stick to them and also which start off the cascade of clotting proteins in the blood
Why is it difficult to stop clotting once started?
Both these reactions on prev flashcard involve positive feedback loops so that once they have started they are difficult to stop.
Once the clotting cascade has started there is formation of the large protein molecule fibrin which makes a mesh in which red blood cells can become entrapped.
What 3 factors cause thrombosis?
Change in vessel wall
Change in blood flow
Change in blood consistents
What is embolism?
Is the process of a solid mass (thrombus) in the blood being carried through the circulation to a place where it gets stuck and blocks the vessel
Name some less common causes of embolus
Air
Cholestral crystals
Tumour
Amniotic fluid
Fat
What would happen if an embolus enters the venous system?
If an embolus enters the venous system it will travel to the vena cava, through the right side of the heart and will lodge somewhere in the pulmonary arteries (depending on its size)
Why can’t an embolus, that has entered venous circulation, then get through arterial circulation?
because the blood vessels in the lung split down to capillary size (through which only single red blood cells can squeeze) so the lungs act as a filter for any venous emboli.
What happens if an embolus enters the arterial system?
it can travel anywhere downstream of its entry point lead to gangrene, MI, stroke
What ischemia?
reduction blood flow to a tissue without any other implications
What is infarction?
Reduced blood flow to a tissue leading to subsequent cell death
What usually causes infarction?
Thrombosis
Why are organs with end arterial supply more susceptible to infarction?
As these organs have a single artery supplying them so they are very suscep- tible to infarction of this supply is interrupted
Name organs with dual arterial supply
Lung- pulmonary vein and bronchial artery
Liver- hepatic portal vein and hepatic artery
Some parts of the Brian under the circle of Willis
Define resolution
Initiating factor is removed
Tissue is undamaged/ able to regenerate
Examples of resolution
In the liver- if the damage isn’t chronic
Superficial cut of skin
Define repair
Initiating factor is still present
Tissue is damaged and unable to regenerate
What is involved in repair
Replacement of damaged tissue by fibrous tissue
Collagen produced by fibroblasts
Examples of repair
Heart after myocardial infarction
Brian after cerebral infarction
Spinal cord after trauma
Deeper cut of skin or scar
Name cells that regenerate
Hepatocytes
Osteocytes
Pneumocyte’s
Blood cells
Gut and skin epithelium
Name cells that do not regenerate
Myocardial cells
Neurones
What is atherosclerosis?
Inflammatory process characterised by hardened plaque formation in the intima of the vessel
How does atherosclerosis cause illness?
by reducing the blood flow in im- portant areas e.g. myocardial infarction in the heart
Time course of atherosclerosis
• birth - no atherosclerosis
• late teenage/early 20s - fatty streaks in aorta, may not progress to established atherosclerosis
• 30s/40s/50s - development of established atherosclerotic plaques
• 40s-80s - complications of atherosclerotic plaques e.g. thrombosis, intraplaque haemorrhage
Risk factors for atherosclerosis
Cigarette smoking
Hypertension
Hyoerlipidemia
Uncontrolled diabetes mellitus
Low socioeconomic background
What causes atherosclerosis?
Damage of endothelial cells
What is a complication of atherosclerosis?
If an atherosclerotic plaque completely blocks an artery then no blood will flow to the organ supplied by that artery and (unless there is a second arterial supply which is unusual in the body) the organ will die (infarct)
What is the effect of pieces of an atherosclerotic plaque breaking off and travelling downstream to block smaller vessels (embolism)?
This may cause small infarcts distal to the main atherosclerotic plaque and over time these cumulative effect of these small infarcts can be significant
What is apoptosis?
Is programmed cell death that takes place in single cells
This prevents cells with accumulated genetic damage from dividing and producing cells which may eventually develop into cancer cells