8558608
Description
Flashcards by Alice Storr, updated more than 1 year ago
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Created by Alice Storr
over 7 years ago
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| Question | Answer |
| Heart rate | Number of times the heart beats per minute |
| Cardiovascular control centre | controls heart rate, located in medulla oblongata, recieves impulses about CO2 levels in blood, sends impulses via accelerator nerve (sympathetic NS) or vagus nerve (parasympathetic NS) to SAN to increase or decrease heart rate. |
| stroke volume | volume of blood pumped out of the left ventricle every time the ventricle contracts (ventricular systole). cardiac output x heart rate = stroke volume |
| cardiac output | stroke volume x heart rate = cardiac output. stroke volume per minute. |
| SAN | Sinoatrial node - group of specialisd muscle fibres in the heart wall which initiate the heart beat (aka pacemaker) |
| Bundle of His | specialised fibres in the heart carry impulses from AVN to ventricle tips, ensure ventricle contracts in a way that squeezes blood upwards through arteries |
| AVN | Atrioventricular node - area of specialised tissue in the wall of the heart between the atria and ventricles. coordinates the heart beat. impulse from SAN is delayed briefly here (0.13 seconds) |
| cardiac cycle | one complete cycle of the heart - systole and diastole |
| electrocardiogram | graphic record of electrical activity of the heart |
| Purkyne fibres | specialised muscle fibres running between right and left ventricles, conducting impulses making the ventricles contract |
| myogenic | muscle which can contract without being stimulated to do so by a nerve (heart is initiated by SAN instead and these are muscle fibres rather than nerves) |
| QRS complex | wave of depolarisation resulting in conraction of ventricles |
| R wave | represents depolarisation of left ventricle (just before the right ventricle) |
| P wave | depolarisation of the atria (from right to left) |
| Q wave | depolarisation of the bundle of His |
| T wave | ventricular relaxation/repolarisation ( |
| S wave | end of depolarisation/contraction of right ventricle |
| QT interval | length of time between beginning of Q wave (depolarisation of bundle of His) and the end of the T wave (repolarisation of ventricles) |
| order of depolarisation and repolarisation (3 stages) | atrial depolarisation (right to left) ventricular depolarisation (left to right) ventricular repolarisation |
| U wave | occurs in 50-75% population |
| Adrenaline role on heart rate | produced by adrenal glands when we are stressed or frightened, increases stroke volume and heart rate which increases cardiac output, dilates blood vessels supplying muscles, stimulating conversion of glycogen to glucose. |
| Angina | pain in chest when heart muscle doesn't revieve enough oxygen-rich blood. If coronary heart muscles can't supply enough oxygen then the heart muscle respires anaerobically, producing lactic acid |
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