Physiology, Health

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Physiology, Health Exercise

• Lesson 5
• Cardiovascular Disease

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What happens when the CVS goes wrong?

• Cardiovascular disease CVD
• E.g
• Atherosclerosis
• Thrombosis
• Angina pectoris
• Myocardial infarction (MI)
• Hypertension
• Stroke

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Atherosclerosis

• Disease process leads to CHD (coronary heart
  disease) strokes
• Fatty deposits either block the artery directly
  or increase the chance of the artery being
  blocked by a blood clot (thrombosis)
• Blood supply can be blocked completely

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Atherosclerosis

• If occurs
• for long the affected cells are permanently
  damaged as starved of oxygen
• in coronary artery? myocardial infarction (MI)
• Cardiac cells start to die within 3-4 minutes
• in artery feeding brain ? stroke
• Brain cells start to die within 8-10 minutes
• If causes narrowing of arteries of legs? tissue
  death/gangrene
• One of major causes of death in Westernised
  societies

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Atherosclerosis-stages

• Endothelial cells lining lumen of artery become
  damaged.
• May be due e.g. to high blood pressure toxins
  from cigarette smoke in blood viral stress
• Inflammatory response.
• Large white blood cells (w.b.c) leave vessels and
  move to artery wall. W.b.c deposits chemicals
  from the blood particularly cholesterol.
• Deposit builds up? atheroma (Greek words- atheros
  gruel oma tumour)

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Atherosclerosis-stages

• Calcium salts and fibrous tissue build up at the
  site to form a hard swelling called a plaque on
  the inner artery wall.
• Artery wall loses some of its elasticity- i.e.
  hardens.
• (Greek word for hardening is sclerosis- hence
  atherosclerosis)
• Artery lumen becomes narrower.
• More difficult for heart to pump blood- so rise
  in blood pressure

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Atherosclerosis

• Dangerous positive feedback loop as plaque raises
  blood pressure
• raised blood pressure increases chance of more
  plaques forming.

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Atherosclerosis

• Plaques tend to occur at sites where changes in
  the blood flow occur, e.g. where blood vessels
  branch
• At this stage there my not be any symptoms
• However if artery becomes very narrow/blocked
  then becomes very difficult to deliver enough
  blood to supply O2 and nutrients ? now symptoms
• Significance is particularly severe if coronary
  artery affected

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Contributory/acceleratory factors to development
of atherosclerosis

• High blood pressure
• Carbon monoxide in cigarette smoke
• Having diabetes mellitus
• High blood cholesterol levels

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Atherosclerosis

• Atherosclerosis can develop progressively from
  teenage to middle age.
• Symptoms do not tend to arise until person over
  50 i.e. until coronary artery blocked or a
  thrombus blocks an artery.
• Aneurysm- when weakened artery walls bulge and
  eventually burst- fatal

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Thrombus

• The plaque has a rough surface so platelets
  attach
• Platelets then change shape from flattened discs
  to spheres with long thin projections ?blood clot
  or thrombus at site which can block the artery
• (Remember platelets create a network which
  becomes a blood clot)

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Thrombus

• If the thrombus breaks loose, embolus, which can
  then travel around the circulatory system until
  it reaches an artery that is too narrow to travel
  down.
• If embolus reaches the coronary artery? embolism
• Part of heart muscle dies? MI
• Severity depends on the area of heart muscle
  affected, size location
• If embolus reaches a brain artery ? stroke

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Thrombus
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CHD

• Includes
• angina pectoris
• MI

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Angina pectoris

• Narrowing of coronary artery which limits O2 rich
  blood that reaches the heart muscle
• Causes chest pain- angina pectoris
• Usually experienced during exertion
• If coronary arteries are narrowed by more than
  50-70, then the arteries cannot supply the needs
  of the heart muscle when it is exercising.

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Angina pectoris

• Heart muscle lacks O2 so respires anaerobically
  so produces lactic acid
• Accumulated lactic acid causes pain in chest/left
  arm/shoulder
• Shortness of breath angina are first signs of
  CHD
• Other symptoms are very similar to indigestion
  e.g. heaviness, tightness, burning pain
  pressure behind breastbone
• Rest removes the pain

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Angina pectoris

• Angina symptoms appear when atherosclerosis is
  quite advanced- i.e. diameter of coronary artery
  reduced by about 70
• There is no permanent muscle damage with angina
• If angina occurs at rest then the coronary artery
  has narrowed to a critical degree

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Myocardial Infarction (MI)

• In UK over 270, 000 people suffer a heart attack
  each year.
• Fatty plaque in coronary artery ruptures so the
  cholesterol released causes rapid blood clot
  formation
• Blood supply to heart completely blocked
• I.e. ischaemic- meaning without blood

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Myocardial Infarction (MI)
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Myocardial Infarction (MI)

• When a heart attack is diagnosed quickly (within
  1-2hours) and the patient reaches hospital in
  time, he or she may be given special clot-busting
  drugs that cause the clot to break up and allows
  the supply of blood to be restored
• If muscle starved of O2 for long (3-4 minutes)
  causes the death of the cells i.e. heart attack
  or MI

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Myocardial Infarction (MI)

• If the zone of the dead cells is only over a
  small area- silent infarction- less likely to
  be fatal
• If it causes the heart to beat irregularly?
  arrhythmia can cause heart failure- so vitally
  important in diagnosis of heart disease
• Approx 50 of patients who develop heart attacks
  have warning symptoms of angina prior to their
  heart attacks

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Hypertension

• Persistently high resting blood pressure
• i.e. systolic blood pressure gt 140 mm Hg
• diastolic blood pressure gt 90 mm Hg
• gt140/90

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Hypertension
diastolic blood pressure Type of hypertension
85-90 Mild
90-104 Moderate
105-114 Moderately high
gt115 Severe
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Hypertension

• Hypertension is the major risk factor for many
  diseases, including CHD
• Contributory factors
• Diet (high salt, high fat)
• Obesity
• Smoking
• Genetic predisposition
• Stress

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Hypertension

• Mostly controlled by
• Alteration to diet
• Exercise
• Medication
• 20 of adult UK population suffer from
  hypertension and are unaware that they have it!

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Stroke

• Thrombus in cerebral artery
• Embolus in cerebral artery
• Haemorrhagic stroke- blood vessel supplying blood
  to brain bursts
• All cause damage or death to brain cells