U2T3 - Keywords Flashcards
Double Circulation
Type of blood circulation in which blood flows through heart twice for each body circuit. Pulmonary circulation separate from systemic circulation. Common in mammals.
Pulmonary Circulation
To + From the Lungs. Small circuit, blood at lower pressure than systemic, this low pressure + low speed allows extra time for gas exchange. Pumped by right side of heart.
Systemic Circulation
To + From the Body. Higher BP to cover greater distance + get to all organs + remove waste at required rate. Pumped by left side of heart. Left muscle therefore thicker.
Arteries
Blood vessels that carry blood away from thloe heart. Divide into arterioles which branch to form capillaries.
Veins
Blood vessels which carry blood to heart. Capillaries come together to form venules which join into veins.
Cardiovascular Disease
CVD is term for conditions affecting heart/blood vessels. I.e. CHD, stroke, peripheral artery disease.
Atherosclerosis
Disease caused by plaques + atheromas building up on artery walls, thickening walls + narrowing lumen. BP increases.
Atheroma
Fatty deposits in artery walls, common cause of angina + flow of O2 blood restricted. Build-up may lead to artery blockage increasing risk of CHD + heart attack. Can occur in any artery so increasing risk of stroke + peripheral artery disease.
Thrombosis
Formation of blood clots within blood vessels.
Coronary Thrombosis
Blood clot in coronary arteries. Can block blood flow so O2 + glucose supply to heart. Heart muscle cells can’t respire so die. Further upstream (nearer artery origin), worse effect + higher likelihood of myocardial infarction.
Myocardial Infarction
Heart Attack
Angiograph
Special x-ray to see inside blood vessels. Die inserted via catheter into blood vessel, passed in through groin or forearm + fed along until reaching interest. Means dye doesn’t go into whole circulatory system. Show narrowed, damaged or blocked vessels.
Aneurysm
Artery wall weakens + creates bulge due to atherosclerosis/other damage. If ruptures, haemorrhage occurs. Early detection stops rupture + internal bleeding.
Septum
Internal wall through heart which separates two atria and ventricles.
Atrioventricular Valves
Between atria + ventricles, tricuspid (right) + bicuspid (left), prevent blood flowing back into atria, when open, pointed cusp ends project into ventricules.
Chordae Tendinae
Tendon like chords (heart strings) which connect pointed ends of cusps and under surfaces to papillary muscles. Stop AV valves being blown inside out from high BP.
Papillary Muscles
Muscles on inner surface on ventricles, connected to AV valves by chordae tendinae.
Semi-lunar Valves
At base of pulmonary artery + aorta. Close to prevent backflow of blood into ventricles when they relax.
Pericardium
Tightly fitting membrane around heart. Anchors heart within thorax + prevents it overfilling with blood. Reduces friction with beating heart muscle + surrounding tissues.
Myogenic
Heart can rhythmically contract + relax of its own accord throughout life. Impulse to contract generated within heart (Myogenic origin) Heart muscle fibres contract rhythmically from the origin until they die. “Contraction is initiated within the heart muscle.”
Myogenic Origin
Impulse to contract is generated within the muscle itself.
Neurogenic Origin
Impulse to contract is generated by nervous stimulation.
Cardiac Cycle
Sequence of events of a heartbeat which causes blood to be pumped all over body. Lasts about 0.8 seconds.
Atrial Systole
Blood returns to heart at low pressure, as both atria fill with blood, pressure increases + they contract, pushing blood past AV valves which are opened by pressure pushing against them into ventricles. Most flows passively so atria don’t have to contract much. Shortest Stage. AV septum stops wave of excitation from SAN node which is what triggers AS. This ensures ventricular systole follows atrial systole.
Ventricular Systole
Atria relax, pressure increases from base of ventricles which then contract forcing blood out of heart into pulmonary artery + aorta, pressure of blood against AV valves causing them to shut creating ‘lub’ sound, stops backflow of blood into atria. These are stopped from being blown inside out by the chordae tendinae. Pressure of blood against SL valves causes them to open.
Diastole
Ventricles relax, pressure in ventricles drops to below that of arteries, higher BP in arteries than ventricles causes SL valves to shut as pockets fill with blood creating ‘dub’ sound + stopping blood moving into ventricles. All heart muscle relaxes + returns to OG size thanks to elastic recoil, blood from vena cava + pulmonary vein enter atria, as this occurs, pressure increases + AV valves pushed open, blood moves from atria to ventricles + cycle begins again. Coronary arteries fill + supply heart with O2 + glucose.
SAN
Sino-atrial node, where heart beat originates. In wall of right atrium. AKA pacemaker.
Wave of Excitation
Electrical impulses which are created by sino-atrial node.
Atrioventricular Septum
Layer of non-conducting material at base of atria. Slows wave of excitation.
AVN
Atrio-ventricular node. Node at base of right atrium.
Purkinje Fibres
Special muscle fibres which pass wave of excitation through to ventricular walls.
Bundle of His
Purkinje Fibres together in interventricular septum (left + right ventricle walls).
Refractory Period
When cardiac muscle has period of insensitivity and doesn’t contract.