Cardiovascular system and diseases Flashcards
Components of the circulatory system
- A central pump - the heart
- A distributary system (away) - aorta, arteries, arterioles
- An oxygenation system - pulmonary vessels/lungs
- A system for exchange - the capillaries
- A collecting system (toward) - veins, vena cava
what are the four heart valves and where are they located?
tricuspid - between right atrium and right ventricle
pulmonary - between right ventricle and pulmonary artery
mitral - between left atrium and left ventricle
aortic - between left ventricle and aorta
Myocardium
The cardiac muscle composed primarily of a collection of specialized muscle cells - contract at their own pace
how are ventricular myocytes arranged?
circumferentially in a spiral orientation
coronary arteries
provide a constant supply of oxygenated blood to the heart
what are the Three major epicardial coronary arteries? what do they support?
Left anterior descending (LAD) artery - left ventricle, Left circumflex (LCX) artery - surroundings, Right Coronary artery - right ventricle
where do myocardial infarctions tend to happen? why?
at the LAD artery - causes pump failure meaning oxygenated blood cannot be taken to the rest of the body
when does Most coronary arterial blood flow to the myocardium occur?
during ventricular diastole, - when the microcirculation is not compressed by cardiac contraction
what does the Cardiac conduction system regulate?
heart rate and rhythm
what are the components of cardiac conduction and where are they 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
• The atrioventricular (AV) node, located in the right atrium along the atrial septum;
• The bundle of His, 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
arrhythmias
Conduction defects due to uncoordinated generation of impulses lead to non uniform and inefficient contraction
Ventricular fibrillation
ventricles are not contracted in a coordinated way
The Frank-Starling mechanism
Increased filling volumes dilate the heart and increase functional cross-bridge formation within the sarcomere to increase contractility
Activation of neurohumoral systems for Myocardial adaptation
Noradrenaline release, which increases heart rate and contractility. RAAS activation and atrial natriuretic peptide release to adjust filling volumes and pressures
Common cardiovascular
diseases
- Atherosclerosis
- Hypertension
- Stroke
- Heart Failure
- Arrhythmia
- Heart valve problems
Structure and function of the venous system
smaller diameter blood vessels, lower pressure, less smooth muscles, less contraction
Structure and function of arterial system
larger diameter blood vessels, higher pressure, more smooth muscles, more contraction
what is the ECM composed of?
elastin, collagen, and glycosoaminoglycans
what factors affect blood pressure?
cardiac
output (heart) and peripheral vascular resistance (vessels)
hypotension
(low pressures) results in inadequate organ perfusion and can lead
to dysfunction or tissue death
90/60
Hypertension
(high pressures) can cause vessel and end-organ damage
140/90
normal blood pressure
120/80
how are high BP and atherosclerosis linked?
high BP causes vessel damage, hardening of walls and plaque formation
risk factors of hypertension
age, genetics, BMI, diet (incl, Na intake), stress
Hypertension classification
Essential (idiopathic) hypertension - primary, multifactorial, genetics important
Secondary hypertension - results from other diseases
regulating blood pressure through cardiac output
blood volume (sodium retention, mineralcorticoids, atriopeptin)
cardiac factors (heart rate and contractility)
regulating blood pressure through peripheral resistance
humoral factors (constrictors and dilators such as hormones and mediators), neural factors (constrictors and dilators), local factors (pH, hypoxia)
give n example of secondary hypertension for
- renal
- endocrine
- cardiovascular
- neurological
Renal - angiotensin II
Endocrine - Cushing’s Syndrome
Cardiovascular - narrow arteries
Neurological - vasopressin
Symptoms of hypertension
Persistent headache, Blurred or double vision, Nosebleeds, Shortness of
breath
complications of hypertension
stroke, retinopathy, vascular disease, renal failure, coronary heart disease
treating hypertension
- ACE inhibitors or angiotensin receptor antagonists - reduce angiotensin II effect
- Beta-blockers - decrease contractility
- Calcium channel blockers - relaxes smooth muscle arteries
- Diuretics - removes water and sodium to reduce body volume
Systemic hypertension
causes left heart hypertrophy (most common)
Pulmonary hypertension
causes right heart hypertrophy
Morphology of hypertensive left ventricular hypertrophy
Left ventricular wall thickening, Increased heart weight, Ventricular wall stiffness impairs diastolic filling causing left atrial enlargement
how to clinically diagnose hypertensive heart diseases
by electrocardiogram or echocardiography
Atherosclerosis
(“hardening of the arteries”) is a generic term for thickening and loss of elasticity of arterial walls
intimal lesions
atheromatous or fibrofatty
plaques which protrude into and obstruct vascular lumens
cholesterol link to atherosclerosis
Associated with increased LDL-cholesterol and reduced HDL-cholesterol
risk factors of atherosclerosis
Non-modifiable: Age, Gender (M>F), Positive family history, Genetic abnormality (eg, ACE gene)
modifiable: Hyperlipidemia, Hypertension, Smoking, Diabetes, Obesity, Physical inactivity
Atherosclerotic plaques features
protrude into vessel lumens, raised lesion with a yellow necrotic core (lipid, debris, foam cells, fibrin) covered by a white fibrous cap (dense collagen). Crystalline cholesterol clefts, a shoulder containing macrophages, and neovascularisation
what are the three principal components of plaques
- Cells: SMCs, macrophages, and other leukocytes (shoulder)
- Extracellular matrices: collagen, elastin, proteoglycans (cap)
- Intracellular and extracellular lipid (core)
early plaque morphology
fatty streaks - lipid filled foam macrophages
foam cells
macrophages that are unable to digest lipids - causes deposition
advanced complications of atherosclerosis
ruptured lesion that thrombose and eventually become a clot
Consequences of
atherosclerotic plaques
rupture or ulceration leads to thrombosis. haemorrhage. atheroembolism. aneurysm
Ischemic heart disease
reduced blood flow due to obstructive atherosclerotic lesions in the coronary arteries
Clinical manifestations of ischemic heart disease
- Angina pectoris
- Myocardial infarction, most important
- Heart failure
- Sudden cardiac death
Angina pectoris
chest pain
Patterns of angina pectoris
1) Stable or typical angina
2) Variant (Prinzmetal, vasospastic) angina
3) Unstable (crescendo) angina
Myocardial Infarction
heart attack - death of cardiac muscle due to
prolonged severe ischemia
Causes of coronary
arterial occlusion
coronary atherosclerosis, vasospasm, emboli from left atrium
symptoms of myocardial infarction
severe chest pain, sweating, nausea and vomiting
aneurysm
dilation of vessel wall
usual duration of angina pectoris
15sec to 15min - +30min is more likely heart attack
main ECG change in myocardial infarction
elevated ST segment
heart failure
impaired ability to function as a pump to support a physiological circulation
when does congestive heart failure occur
when heart is unable to pump blood at a rate sufficient to meet the metabolic demands or only at an elevated filling pressure
Different forms of heart failure
acute, chronic, left, right
causes of left heart failure
1) congestion of the pulmonary circulation - cant be taken back to heart
2) stasis of blood in the left-sided chambers - contraction not forceful enough
3) hypoperfusion of tissues leading to organ dysfunction
morphological and clinical effects of left heart failure
left ventricle hypertrophy and dilation, left atrium dilation. pulmonary congestion and odema
right heart failure
secondary consequence of LHF due to increase in pressure in the pulmonary circulation
example of a hallmark of right heart failure
pretibial and pedal oedema
