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.
Coronary Circulation
Flow of blood through coronary arteries + veins branching from aorta.
ECG
Electrocardiogram. Record of electrical events associated with beating heart. Electrodes attached to chest skin + connected to monitor producing ECG trace. Possible because of wave of electricity passing over heart surface when it beats.
Blood
Specialised tissue containing number of different living cell types floating in plasma.
Plasma
Non-living pale yellow watery liquid. 55% of blood. 90% water and 10% dissolved substances. These include salts, glucose, amino acids, vitamins, urea, proteins + fats. Transports cells + other substances present in blood.
Erythrocytes
45% of blood. Non-nucleated (more room for haemo) biconcave (increases SA:V ratio) disc with no mitochondria (allows lots of haem + efficient diffusion) that carry oxygen around body. Haemoglobin present. New RBCs produced in red bone marrow of ribs, sternum, vertebrae, skull + long bones. Transports respiratory gases, O2 bound to haemoglobin. Small so haem close to surface for O2 transport, easy to move through capillaries.
Haemoglobin
Present in RBCs. Combines with O2 in lungs to form oxyhaemoglobin. Consists of 4 polypeptide chains (quaternary structure) with haem prosthetic group at centre of each chain (tertiary structure), each containing 1 iron atom with 1 O2 bonded to each iron. Each molecule therefore binds to 4 O2 atoms. Conjugated protein. Respiratory pigment. Globular.
Leucocytes
White blood cells, involved in immune system.
Polymorphs
70% of WBCs. Multi-lobed nucleus + granular cytoplasm, some are microcytes, others are involved in inflammation/allergies. They can move from capillaries to infection sites.
Microcytes
Small WBCs which engulf bacteria.
Monocytes
5% WBCs. Large kidney/bean shaped nucleus. Longer lived than polymorphs. Macrophages. Can carry out phagocytosis.
Macrophages
WBCs which engulf bacteria.
Lymphocytes
20-25% WBCs. Large, round nucleus, small amount of cytoplasm. T cell + B cell.
T Cells
Act on tumours + virus infected cells.
B Cells
Produce plasma cells which produce antibodies + memory cells.
Platelets
Instrumental in blood clotting + minor blood vessel repair. Very small, cell fragments.
Ultrafiltration
At arterial end of capillary bed, blood at high hydrostatic pressure due to narrow vessels so plasma containing small molecules (O2, C6H12O6), squeezed through permeable capillary walls.Cells + proteins too big to leave capillary so stay in blood.
Lymph
Not all tissue fluid returns to capillary at venous end. Instead 1/10 enters lymph capillaries, part of lymph system. Now becomes lymph. Returns to blood through thoracic duct.
Lymph Vessels
Similar to veins. Thin walled with valves.
Haemophilia
Prevents blood clotting due to missing link in chain i.e. clotting factors.
Partial Pressure
Measure of amount of gas present in a mixture of gases. Frequently used when describing O2 transport by haemoglobin. Measure amount of pressure exerted by gas.
pO2
Partial pressure of oxygen. Measure of O2 conc. Greater conc of dissolved O2 = higher partial pressure. Measure in kPa (kilopascals)
Oxygen Dissociation Curve
Relationship between haemoglobin + oxygen as conc of O2 around haemoglobin molecule changes. First molecule hardest to bind so others easier and levels off at fourth.
Conformational Change
Distortion/shape change in haemoglobin molecule.
Cooperative Loading
In alveoli, pO2 is high + haem saturated with O2. (1st O2 molecules attaches with difficulty but produces conformational change) Second easier + so on until all 4 attach + saturated with O2.
Sigmoidal Curve
Characteristic S-shape of a curve. (Oxygen Dissociation Curve)
Bohr Effect
Increased CO2 conc shifts oxygen dissociation curve to right (where CO2 conc high in actively respiring cells), O2 released from oxyhaemoglobin even quicker. This means oxyhaemoglobin releases O2 where most needed.
Myoglobin
Respiratory, oxygen-binding pigment found in red muscle (gives it’s colour), single polypeptide unit, higher O2 affinity than haemoglobin, oxymyoglobin more stable than oxyhaemoglobin. Normally saturated with O2 so acts as O2 store.
Dalton’s Law
Each gas in a mixture of gases exerts its own pressure as if all other gases weren’t present.
Atmospheric Pressure
pO2 + pCO2 + pN2 + pH2O = 760 mm Hg.
Fibrillation
Heart contractions irregular so less blood leaving heart + heart becomes deprived of O2.
Vasoconstriction
Constriction of blood vessels, increases blood pressure.
Vasodilation
Dilatation of blood vessels, decreases blood pressure.
Oxygenated
Supplied with oxygen.
Deoxygenated
Oxygen removed.
Systole
Contraction of the heart.
Cardiac Output
Amount of blood heart pumps through circulatory system in 1 min. (Stroke volume + heart rate = cardiac output)
Stroke Volume
Amount of blood put out by left ventricle of heart in 1 contraction.
PCG
Phonocardiogram. A graphic record of heart sounds + murmurs produced by a phonocardiograph.
Thromboplastins
Complex enzyme found platelets which helps convert prothrombin to thrombin in blood clotting.
Lub Sound
First heart sound (S1) caused by closure of atrioventricular valves at start of systole.
Dub Sound
Second heart sound (S2) caused by closure of semilunar valves at end of systole.
Affinity
The degree to which a substance tends to combine with another.
Loading Tension
Partial pressure at which haemoglobin is 95% saturated with O2.
Unloading Tension
Partial pressure at which haemoglobin is 50% saturated with O2.
Genetic Predisposition
Possessing genes which increase individual’s susceptibility to a certain disease.
Myocardial
Occurring in the heart muscle.
Infarction
Death of tissue resulting from O2 deprivation.
Diagnosis
Identification of a medical condition by symptom examination.
Coagulation Cascade
The way blood clots.
Phagocytosis
Engulfing of bacteria + digestion.
