Cardiovascular system and diseases I Flashcards
what is the purpose of the valves in the heart
maintain uniddirectional blood flow through the heart
what is the cardiac muscle mainly composed of
cardiac myocytes
ventricular myocytes are arranged how
this is to enable what
CIRCUMFERENTIALLY in a SPIRAL ORIENTATION
enables contraction and relaxation
what are the 3 major epicardial coronary arteries
1) left anterior descending (LAD) artery
2) left circumflex (LCX) artey
3) right coronary artery
when does most coronary arterial blood flow occur
during VENTRICULAR DIASTOLE when the microcirculation is not COMPRESSED by cardiac contraction
the SA node does what
pacemaker of the heart
where is the SA node located
near the junction of the right atrial appendage and the superior vena cava
the AV node location
right atrium along atrial septum
bundle of His location
from right atrium to summit of ventricular septum
in the PQRST wave what does each wave/segment mean
inc PR segment
P: atrial depolarisation
PR segment: time taken from atria to ventricle
QRS: ventricular depolarisation
ST segment: period between ventricular depolarisation to myocardial contraction
T wave: ventricular repolarisation
conduction defects (eg arrhythmias) are caused by what
uncoordinated impulse generation
what is the Frank-Starling mechanism
a compensatory mechanism: inc FILLING VOLS DILATE the heart and O INC FUNCTIONAL CROSS-BRIDGE formation within sarcomeres O INC CONTRACTILITY
give 3 compensatory mechanisms for the heart
1) Frank-Starling mechanism
2) Activation of neurohormonal systems
3) myocardial mechanisms
give examples of ways NEUROHORMONAL SYSTEMS can act as compensatory mechanisms
1) release NORADRENALINE by adrenergic cardiac nerves of the autonomic NS (inc HR, myocardial contractility, vascular resistance)
2) renin-angiotensisn-aldosterone system ACTIVATION
3) release of atrial natriuretic peptide
common cardiovascular diseases
- atherosclerosis
- hypertension
- stroke
- heart failure
- arrhythmia
- heart valve problems
hypotension results in what
inadequate organ perfusion and can lead to dysfunction or tissue death
hypertension results in what
vessel and end-organ damage
hypertension is responsible for what % of deaths due to heart disease
45%
hypertension is responsible for what % of deaths due to stroke
51%
what is classed as clinically significant hypertension
sustained systolic >139 mm Hg
sustained diastolic > 89mm Hg
what are the risk factors for hypertension
- age
- genetics: African and Caribbean origin
- BMI
- diet (Na+ intake)
- stress
what are the 2 types of hypertension
1) ESSENTIAL (idiopathic)
- 90-95% of cases
- complex, multifactorial (inc genetics)
2) SECONDARY
how is blood pressue calculated
cardiac output x peripheral resistance
what can affect cardiac output
1) BLOOD VOLUME
(Na, mineralocorticoids, atriopeptin)
2) CARDIAC FACTORS
(heart rate, contractility)
what can affect peripheral resistance
1) HUMORAL FACTORS
- constrictors: Angiotensin II, Catecholamines, Endothelin
- dilators: Prostaglandins, Kinins, NO
2) LOCAL FACTORS:
pH, hypoxia
3) NEURAL FACTORS:
- constrictors: α-adrenergic
- dilators: β-adrenergic
what are the symptoms of hypertension
- persistent headache
- blurred/double vision
- nosebleeds
- shortness of breath
what is a possible effect of hypertension on the brain
- TIA (transient ischaemic attack)
- stroke
what is a possible effect of hypertension on the EYE
retinopathy
what is a possible effect of hypertension on the legs
peripheral vascular disease
what is a possible effect of hypertension on the kidneys
renal failure
what is a possible effect of hypertension on the heart
LVH- left ventricular hypertrophy
CHD- coronary heart disease
HF- heart failure
what are the 4 types of antihypertensive drugs
1) ACE inhibitors/ angiotensin receptor antagonists
2) Beta-blockers
3) Ca channel blockers
4) Diuretics
what heart diseases can hypertension cause
- systemic hypertension causes LEFT HEART HYPERTROPHY
- pulmonary hypertension causes RIGHT HEART HYPERTROPHY
what is the morphology of hypertensive left ventricular hypertrophy
- left ventricle wall thickens
- inc HEART WEIGHT
- ventricular wall STIFFENS which impairs DIASTOLIC filling causing LEFT ATRIAL enlargement
if hypertensive heart disease is in the early stages, what is experienced by patient
how is it diagnosed
if it progresses what can it cause
usually ASYMPTOMATIC
- diagnosed using ELECTROCARDIOGRAM or ECHOCARDIOGRAPHY
- if progression: can cuase HF or ISCHAEMIC HEART DISEASE
