Cardiovascular system and diseases I Flashcards
What does the heart have 4 valves
- To maintain unidirectional blood flow through the heart
What are the components of the circulatory system
- A pump - the heart
- A distributary system, - aorta, arteries, arterioles
- An oxygenation system - pulmonary vessels/lungs
- A system for exchange - the capillaries
- A collecting system - veins, vena cava
What are the 4 valves in the heart
- Pulmonary valve
- Aortic valve
- Mitral valve
- Tricuspid valve
Why is Myocardium?
- The cardiac muscle composed primarily of a collection of specialised muscle cells called cardiac myocytes
How is Ventricular myocytes arranged
- Ventricular myocytes are arranged circumferentially in a spiral orientation and contract during systole and relax during diastole
How does the heart meet its energy needs?
- To meet energy need, cardiac muscles rely almost exclusively on constant supply of oxygenated blood via the coronary arteries
What are the 3 major epicardial coronary arteries
- Left anterior descending (LAD) artery
- Left circumflex (LCX) artery
- Right Coronary artery
When does most coronary arterial blood flow to the myocardium occur?
- Most coronary arterial blood flow to the myocardium occurs during ventricular diastole, when the microcirculation is not compressed by cardiac contraction
The heart is an excitable tissue, what does this mean?
- Relies on electrical activities
What is the cardiac conduction system
- Regulates the heart rate and rhythm
What is the Sinoatrial (SA) node and where is it located?
- The sinoatrial (SA) pacemaker of the heart, the SA node, located near the junction of the right atrial appendage and the superior vena cava
Where is the AV node located
- located in the right atrium along the atrial septum
Where is the bundle of his located
- which courses from the right atrium to the summit of the ventricular septum; and its major divisions
- The right and left bundle branches, which further arborize in the respective ventricles through the anterior - superior and posterior-inferior divisions of the left bundle and the Purkinje network
What is the P wave in electrocardiogram tracing?
- P wave: Atrial depolarization
What is the PR segment in electrocardiogram tracing?
- PR segment: Time taken from atria to ventricle
What is the QRS complex in electrocardiogram tracing?
- QRS complex: Ventricular depolarisation
What is ST segment in electrocardiogram tracing?
- ST segment: Period between ventricular depolarisation to myocardial contraction
What is T wave in electrocardiogram tracing?
- T wave: Ventricular repolarisation
How does disorders of cardiac conduction occur?
- Conduction defects (arrhythmias) due to uncoordinated generation of impulses lead to non uniform and inefficient contraction of the heart.
What is the Frank-Starling mechanism?
- Increased filling volumes dilate the heart and thereby increase functional cross-bridge formation within the sarcomeres -> increase contractility
What are the 3 compensatory mechanisms
- The Frank-Starling Mechanism
- Myocardial adaptations, including hypertrophy with or without cardiac chamber dilation
- Activation of neurohumoral systems
What happens in the activation of neurohumoral systems
1) Release of noradrenaline by adrenergic cardiac nerves of the autonomic nervous system (increase heart rate, myocardial contractility, vascular resistance)
2) Activation of the renin-angiotensin-aldosterone system
3) Release of atrial natriuretic peptide
Common cardiovascular diseases
- Atherosclerosis
- Hypertension
- Stroke
- Heart failure
- Arrhythmia
- Heart valve problems
What is Blood Pressure?
- a functions of cardiac output and peripheral vascular resistance
If blood pressure is not maintained what will happen?
- Systemic and local tissue blood pressures must be maintained within a narrow range
- If its too low or high it will lead to Hypotension or Hypertension
What is Hypotension?
-low pressure
- results in inadequate organ perfusion and can lead to dysfunction or tissue death
What is Hypertension?
- high pressure
- can cause vessel and end-organ damage
Name the parameters for Hypertension
- A sustained diastolic pressure greater than 89 mm Hg
- or a sustained systolic pressure in excess of 139 mm Hg
- associated with a measurably increased risk of atherosclerosis
What risk factors are there that determine blood pressure variation within and between population
- Age
- Genetics: African or Caribbean origin
- Body mass index
- Diet, sodium intake
- Stress
What are the different hypertension classification
- ESSENTIAL (idiopathic) hypertension: ~90-95% cases, a complex multi-factorial disorder. Genetic factors play an important role
- SECONDARY hypertension: results from another disease
What Blood pressure effected by?
- Cardiac output
- Peripheral resistance
What is the equation for Blood pressure, Cardiac output and Peripheral resistance
BP = Cardiac output X Peripheral resistance
What effects the Cardiac output?
- Cardiac factors: heart rate, contractility
- Blood volume: Na, Mineralocorticoids, Atriopeptin
What effects Peripheral resistance?
- Humoral factors: Constrictors (Angiotensin II, Catecholamines, Endothelin), Dilators (Prostaglandins, Kinins, NO)
- Neural factors: Constrictors (alpha - adrenergic), Dilators (Beta-adrenergic)
- Local factors (pH, hypoxia)
What are the pathogenesis of secondary hypertension
- Renal
- Endocrine
- Cardiovascular
- Neurological
Symptoms of hypertension
- Persistent headache
- Blurred or double vision
- Nosebleeds
- Shortness of breath
What are the treatments for hypertension
- Antihypertensive drugs
What does Antihypertensive drugs consists off
- ACE inhibitors or angiotensin receptor antagonists
- Beta-blockers
- Calcium channel blockers
- Diuretics
Persistent hypertension without treatment can cause what?
- Pressure overload and ventricular hypertrophy
- Morphology of hypertensive left ventricular hypertrophy
Explain systemic and pulmonary hypertension
- Systemic hypertension causes left heart hypertrophy (most common)
- Pulmonary hypertension causes right heart hypertrophy
Explain the morphology of hypertensive left ventricular hypertrophy
- Left ventricular wall thickening
- Increased heart weight
- Ventricular wall stiffness impairs diastolic filling causing left atrial enlargement
What can Hypertensive heart disease progress too
- Heart failure or ischemic heart disease
What happens in compensated stage of hypertensive heart diseases
- Compensated stage may be asymptomatic and can be diagnosed by electrocardiogram or echocardiography
