Cardiovascular disease Flashcards
What is most cardiovascular diseases related to
Blood vessels, not heart
What is major cause of death in US
Heart disease - 26.6%
Stroke = 5.9% = 3rd
What are the cardiovascular diseases?
- Pericarditis
- Valve defects
- Defects in the specialised excitatory and conductive system
- Hypertension - high b.p
- Assorted congenital heart defects
What is Pericarditis
Inflammation of pericardium
Acquired disease
Won’t kill you but lead to conditions that might kill you
Fluid pericardium produces too much pressure on heart or too little - heart beating in envionment with not enough lubrication = heart function less efficiently
What are the two types of valve defects
Stenosis
Regurgitation
= valves not opening enough - too narrow = blood flows back down heart
What involves heart not functioning properly
- Wont beat properly
- Won’t push out as much blood
- Disrupt normal rhythm
What are the 3 defects in the specialised excitatory and conductive system
- Tachycardia and Bradycardia - heart beat too slow/fast
- Ventricular fibrillation - heart high frequency contractions
- Ectopic pacemaker - another part of system takes over
- Heart block - break in B.Of.His
What does specialised excitatory and conductive system allow
Heart maintain regular contraction without input from nervous system
What is the assorted congential ( born with ) heart defects?
- Septal defects
- Development of single ventricle
- Contraction of aorta (narrowing)- if blood vessels too big, it will press on blood vessels underneath- causing narrowing
What is Septal defect
(Hole in heart)- oxygenated and deoxygenated blood mix between 2 ventricles - sometimes hole doesnt completely close between left and right ventricle
What is contraction of aorta as defect
If blood vessels too big, it will press on blood vessels underneath- causing narrowing
What is the structure of blood vessels - 3 broad categories
Veins
Arteries
Capillaries
What do veins and arteries act as
Pipes - take blood from A - B, no gas exchange
Veins- bring blood to the heart
Arteries- take blood from the heart
Role of capillaries
Gas and nutrient exchange
What are the 3 layers of the arteries
Tunica Interna
Tunica Media
Tunica Externa
What is the role of tunica interna
It provides a frictionless surface for the movement of blood - so you dont get blood clotting
What are the endothelial cells?
- are continuous with heart
- have smooth frictionless lining for both blood vessels and heart
Location of the endothelial cells?
sits on the basement membrane
What is the role of internal elastic lamina?
separates the tunica interna from the tunica media
What is the inner layer of a blood vessel?
Tunica interna
simple single squamous epithelium, sitting on a basement membrane, surrounded by internal elastic lamina
What is the bulk of the artery - middle layer ?
Tunica Media
How many layers are arteries made up of
3
What are arteries mostly made of
Mostly muscular
up to 40 layers of smooth muscle
some elastic and collagenous connective tissue.
Which arteries are close to heart
Big arteries - aorta
Elastic/conducting arteries with elastic properties
Which arteries are further down from heart
Smaller arteries and capillaries
What can the tunica media be innervated by
The sympathetic branch of the ANS
What supplies the tunica media and externa of larger vessels
Vaso Vasorum
Blood vessels in blood vessels -have vessels in their walls called Vasa Vasorum
How do different arteries vary
In the thickness and composition of various layers
What is it internal elastic lumina
Elastic layer of connective tissue
How often does tunica interna turn over
At a rate of 5% of endothelial cells a day
Two properties of the endothelial cells
- Sits on basement membrane
- Continuous with heart, smooth frictionless lining of blood vessels and heart
What don’t elastic arteries have so much of
Have little smooth muscle
Why are arteries elasticated
Allows them to smooth out the blood flow near the heart
What happens to arteries when heart contracts
Blood pushed into these arteries and gets bigger - dilate
What happens to arteries when heart relaxes
Due to their elastic properties, they collapse down which evens out pressure
What do muscular arteries have a tunica media composed of and what is role
Primarily smooth muscle
Distribute blood and change diameter
What do elastic ( conducting ) arteries have a tunica media composed of
Elastic tissue laminae
What is tunica media mostly made of
Concentric layers of smooth muscle
What don’t you want muscles in blood vessels to do
To contract and squeeze or move blood along
What do you want muscles in blood vessels to do
To make blood vessels wide and narrow to regulate b.p = redirect blood
Close blood vessels down if it gets injured
Close down circulation in bits of body when its cold = close down blood supply to finger and toes = gets cold outside to keep up core temp
What else does the tunica media have?
Nerve supply to artery- sympatheic NS innervates smooth muscle of most arteries
What does the tunica media mostly have
Smooth muscle and collagenous elastic connective tissue
What can’t you do if you have a big artery
Supply tunica media from blood in lumen of vessel so big vessels have vessels in their walls = vasa vasorum - vessels of vessels
What is the role of external elastic lumina
Separate tunica media from tunica externa
What is the outer layer of artery called and what is it made of
Tunica externa AKA Adventitia - several layers of longitudinal colagenous connective tissue = tough outerprotective coat
What does recoil of arteries help to do
Push blood along
What does contracting and relaxing of smooth muscle of tunica media do
Distribute blood to different organs and regions of body
Where are muscular arteries found
Further down system
What is different about these elastic arteries?
- They dont have that much smooth muscle in the tunica media
- Mainly have elastic tissue
What are the arteries closest to the heart known as?
Elastic/conducting arteries (with the same 3 layers)
What is diameter of arterioles
Small diameter = less than 0.5mm
What is role of arterioles
Regulate bp
What do arterioles consist of
Endothelium with a bit of rings of smooth muscle cells around them
What dont arterioles have
3 coats or layers
What is diameter, length and total surface area of capillaries
Small diameter = 7-9 um
length= 0.25-1mm
Total length in body = 96,000km with surface area 6000m2
How are arterioles linked to venules
By extensive capillary beds
What are two things that capillaries have
Endothelium
Basement membrane
What does distrubution of capillaries depend on and example
Tissue
e.g. skeletal muscle have lots of capillaries as it uses lots of O2, cornea have no capillaries and tendons little capillaries
Role of capillaries
Exchange of nutrients and respiratory gases
How many miles of capillaries in body
60,000
What are the two main types of capillaries
Continuous
Fenestrated
Continuous capillaries
Adjacent endothelial cells (which sit on the basement membrane) are joined by tight junctions.
The exchange of nutrients go through the cells called Pinocytic vesicles
Fenestrated capillaries
60-100nm
Lots of pores covered by a thin membrane over it.
It is for the rapid exchange of nutrients
e.g eye= behind retina, within the ciliary body you have a lot of fenestrated capillaries
how do you control capillary blood flow?
Rings of smooth muscle= Pre- capillary sphincter
- When they contract, they stop blood from going to capillary bed
- the blood will go straight from the arteriole to the venule
- Deoxygenated blood ends up in the venule
What is different about these elastic arteries?
- They dont have that much smooth muscle in the tunica media
- Mainly have elastic tissue
What are the arteries closest to the heart known as?
Elastic/conducting arteries (with the same 3 layers)
What is diameter of arterioles
Small diameter = less than 0.5mm
What is role of arterioles
Regulate bp
What do arterioles consist of
Endothelium with a bit of rings of smooth muscle cells around them
What dont arterioles have
3 coats or layers
What is diameter, length and total surface area of capillaries
Small diameter = 7-9 um
length= 0.25-1mm
Total length in body = 96,000km with surface area 6000m2
How are arterioles linked to venules
By extensive capillary beds
What are two things that capillaries have
Endothelium
Basement membrane
What does distrubution of capillaries depend on and example
Tissue
e.g. skeletal muscle have lots of capillaries as it uses lots of O2, cornea have no capillaries and tendons little capillaries
Role of capillaries
Exchange of nutrients and respiratory gases
How many miles of capillaries in body
60,000
What are the two main types of capillaries
Continuous
Fenestrated
Continuous capillaries
Adjacent endothelial cells (which sit on the basement membrane) joined by tight junctions.
The exchange of nutrients go through the cells called Pinocytic vesicles = how nutrients get in and out of capillary
Fenestrated capillaries
60-100nm
Lots of pores covered by a thin membrane over it.
It is for the rapid exchange of nutrients
e.g eye= behind retina, within the ciliary body you have a lot of fenestrated capillaries for exchange of nutrients
how do you control capillary blood flow?
- Rings of smooth muscle= Pre- capillary sphincter - when they contract, they stop blood from going to capillary bed. The blood will go straight from the arteriole to the venule
- Deoxygenated blood ends up in the venule
- Shut down capillary beds by contraction of pre - capillary sphincter
What is the structure of the vein/venule?
- Diameter= 0.2-1mm
- Thin walls - vein- see blood through them
- Consist of endothelium and tunica externa
- Larger lumen than arterioles but thinner walls = appear darker, see blood through them
- Tunica media and interna is reduced/thinner= much less smooth muscle
- Tunica externa= thicker
- Same 3 tunics as arteries
How do the blood vessels appear in the fundus of the retina?
- Veins = darker- due to their thinner walls
- Artery- lighter - big thick walls
- Also arteries cross over veins = arteries lie near vitreous, sometimes squashing them
- Usually arteries on top of veins
How does blood pressure vary between the veins and arteries?
Veins have low B.P as they are further from heart so less variation = veins have valves to help fight gravity.
Arteries have a higher pressure than in veins.
In the vena cava there’s no pressure at all because its further from heart - all vessels elastic and less variation
What are the properties of the veins in the leg?
- Veins have valves in them = prevent backflow
- pushes blood up the veins when heart contracts
- when heart relaxes, blood flows down veins and valves shut
- Skeletal muscle of the leg (muscle around blood vessel)- contract and help squeeze blood up the veins
What are varicose veins?
When valves break down ( malfunction ) in veins = pooling of blood
Valves seize to function properly and blood accumulate
What causes varicose veins
- Any condition that puts excessive pressure on the legs or abdomen = downward pressure on veins and vessels
Who is most vulnerable to varicose veins
pregnancy, obesity, standing up for long periods
What is an example of a pathology of veins
Varicose veins
What is a main disease of blood vessel?
Artherosclerosis (atheroma)
What is artherosclerosis?
- deposition of fibrous growths (plaques) within the tunica interna of arteries
- causes heart attack,stroke
- Loss of elasticity of blood vessels
- depositing on blood vessels (mainly arteries) of dense fibrous PLAQUES - nearly completely closed down artery
What is artherosclerosis responsible for
50% of all mortality in the USA, Europe and Japan
What is senile artherosclerosis
- Loss of elasticity of blood vessels in older people - atheroma is a form of this
What is artherosclerosis plaque
Deposition of dense fibrous plaques in the blood vessels walls
How does atheroma form?
- Inside of blood vessel gets damaged i.e. injury to blood vessel wall- endothelium damaged due to high B.P, hypertension, smoking, virus
- Damaged endothelial cells release chemotactic factors (|chemical signals) that signal to repair it
- Lead to the accumulation of LDL from the plasma which oxidise LDL and cholestrol
- LDL deliver cholesterol to tissues
- Macrophages ( WBC ) engulf oxidised lipotproteins and cholesterol and form cells called FOAM CELLS which are yellow. They cause the formation of a fatty ‘yellow streak’ in the vessels tunica interna which is a combination of cholestrol, LDL and proteins being oxidised
- Smooth muscle migrates from tunica media to tunica interna to prevent more damage. Migrated smooth muscle cells replicate and produce collagenous connective tissue
- Calcium deposits from blood plasma are formed and infiltration of WBC
- Lump in tunica interna and tunica media starved of oxygen and scar tissue forms
- Blood vessel lumen decreased
What contributes to atheroma
male and over 40 overweight no excerise diet stress alcohol smoking diabetes oral contraceptives genetics
What is biggest contributor to heart disease
Smoking
What is meant by artiology
Factors associated with….
i.e what contributes to it
What are the consequences of atheroma
- smaller blood vessels may become blocked
- plaques may become the site of thrombosis
- a piece of plaque become detached and form an embolism
- a plaque can be the site of aneurysm
What % of American 10-14 year olds already had a fatty streak of atheroma
40
Consequence of atheroma -smaller blood vessels may become blocked
Arteries become narrowed and blood flow decreases in atherosclerosis - not that possible in larger arteries
Tissue may not get enough O2
what is thrombosis ?
When a blood clot forms on atheroma plaque = blood clot in unbroken vessel = more likely
why is it unusual to get blood clot in vessels?
.Smooth endothelium giving you smooth frictionless flow of blood
.Blood clot will only occur if flow of blood is turbulent = thrombosis = may block vessel
What is deep vein thrombosis caused by
. endothelial damage
. hypercoagulability - blood vessel chemistry can change = more likely for blood clot to form
. venous stasis - slow blood flow in vein usually of legs
what are the symptoms of Deep vein thrombosis
. pain
. swelling
. redness
. warmness
what is venous thromboembolism ?
it is a consequence of thrombosis where part of blood clot becomes detached and travels to the lungs
- Bit of clot breaks off and starts circulating in blood until it gets to lungs - that bit thrombosis will block vascular system of lungs
what is embolism?
obstruction of an artery, typically by a clot of blood or an air bubble or plaque
Anything that circulates in vascular system which causes blockage of vessel
Why MIGHT atheroma block vessel but probably not
Probably cause blood clot and/or embolism form - come from blood clot or piece of fat/tumour/plaque which circulates in system until it impacts on vessel blocking it
What is an aneurysm
Weaken blood vessels wall = blood vessel wall bulges out
What is saccular aneurysm
An aneurysm that resembles a small sack - on 1 point
What is fusifrom aneurysm
Involves the entire circumference of the vessel
What happens when aneurysms burst
Leads to haemorrhages in brain
What is site of thrombosis
Aneurysms
How can you fix aneurysms
They can be clipped or bound
Summary of cardiovascular disease
atheroma is growth of plaques in the walls of artery this leads to
. aneurysm
. thrombosis - blood clot
. embolism
leading to blockage
leading to ischaemia - not enough oxygen in tissue
leading to infraction - tissue death due to lack of blood supply following blood vessel blockage
- end results = BLOOD VESSEL BLOCKED
what does the size of infracts depend on ?
. extent of collateral circulation - how many alternative blood supplies are there to that structure
. duration of ischaemia - how long did O2 stay cut off
. susceptibility of tissue to ischaemia
where do infracts occur ?
infracts can occur everywhere in the body
. spleen
. kidney
. liver
what does the seriousness of an infract depend on?
The tissue
What is ischaemia
Lack of oxygen
what is the most susceptible tissue to infarcts ?
. CNS tissue - neurons in CNS
. CNS tissue need continuous supply of oxygen = lack of O2 is severe = sensitive to lack of O2
. CNS tissue does not regenerate = once neurons die, they stay dead = CNS irreversible
What is stroke
Death of neurons in CNS due to lack of oxygen
Cardiovascular accident
what are the two types of CNS strokes ?
. haemorrhagic - aneurysm bleed in brain = aneurysm = 20%
. ischaemic/occlusive - blood vessel gets blocked
what is an example of organ that can have multiple infracts ?
kidneys
have a large functional reserve and extensive and multiple infracts are needed to impair function noticeably
You can almost wipe out 80% of kidney with infarcts before noticing
What organs are sensitive to ischaemia
Heart
CNS
Why is myocardial infarction serious
- the heart needs to keep beating uninterrupted
2. cardiac muscle is amitotic ( stays dead once killed )
what is the function of the right and left coronary arteries ?
they supply the heart muscle itself with blood
they are susceptible to plaque formation
what is coronary arterial disease / ischaemic heart disease ?
. the narrowing of the coronary arteries by atheroma results in the heart muscle receiving insufficient oxygen leading to impaired contraction due to atheromal plaque formation in one of coronary arteries = insufficient blood supply to heart muscle itself
- Atheroma in coronary arteries
what is the consequence of atheroma in coronary arteries ?
. angina pectoris
. myocardial infraction ( heart attack )
what is angina pectoris ?
caused by short term inadequacy of the blood supply to the heart during times of increased demand = indicates you have impaired coronary circulation
e.g. stress
During an attack there is no tissue death = no infarct
Atheroma plaque in coronary arteries = in times of increased demand not enough blood can get through coronary arteries = sharp attack of pain in chest through to arms
what is myocardial infraction ( heart attack )
blood supply is disrupted for longer
e.g if thrombosis forms on an atheromatous plaque in the coronary arteries , heart muscle may die = heart receives lack of O2
What is the lease severe consequence of atheroma in coronary arteries
Angina Pectoris
what does the severity of infarcted myocardial tissue depend on ?
Area of blockage and which part of heart dies
Size and location
what are causes of death following myocardial infarction ?
- insufficient cardiac output - not enough blood pushed if in left ventricles = bits of body starved of O2 = death
- rupture of infracted area some time after attack
- ventricular fibrillation - heart quivers instead of pumping due to disorganized electrical activity in the ventricles.
- pulmonary oedema- fluid accumulates in the air sacs of the lungs - If left ventricle not pushing out enough blood - all blood fill pulmonary vein in lungs to attempt to lower b.p,fluid in lungs
how to prevent myocardial infraction ?
- clot bursting drugs
- drugs to prevent clots forming ( aspirin, heparin )
- coronary by-pass surgery
- angioplasty/stent
- injection of stem cells into infracted area to produce new cardiac muscle
How do clot bursting drugs prevent myocardial infarction
Dissolve blood clots once its formed - have to recognize it quickly
How does coronary by-pass surgery prevent myocardial infarction
By - pass blockage = blood vessels from patients own body - sew one end into aorta - major arteries and other end = bung blockage = bypass it and get blood into coronary circlulation
How does angioplasty/stent prevent myocardial infarction
Insert catheter into blood vessels ( tube ) - goes up to where atheromatous plaque is and blow air into tube and inflate a baloon = squash plaque. Deflate baloon and pull out catheter = widens blood vessel or spring coiled around baloon so when you deflate it and pull it out, spring stays in place = stent
How does injection of stem cells into infracted area prevent myocardial infarction
Pluripotent stem cells = develop into any tissue in body
stem cells from bone marrow - inject them into where infarct is = regenerate cardiac muscle
what are examples of drugs to lower blood pressure and lessen risk of CVA ?
- aspirin - inhibits production of thromboxane - makes blood clots less likely to form - interferes with blood platelets
- ACE inhibitor - prevents vasoconstriction - wider vessels via renin pathway = stops conversion of Angiotensin I to Angiotensin II
- statins - lower cholesterol, plant derived drug
- arterial calcium channel blocker - prevents vasoconstriction - stops smooth muscle in vessel contracting - blood vessels dilate
