Chapter 5 Heart and monitoring heart function Flashcards

Question

Explain how high levels of saturated fats lead to coronary heart disease

Answer 1

raises LDL and LDL:HDL ratio LDLs deposit cholesterol in wall of coronary artery causing an atheromatous plaque reduces lumen size which reduces oxygen supply to cardiac muscle --> coronary thrombosis --> myocardial infarction

Answer 2

o Specialised muscle as doesn’t rhythm require nerve stimulation to contract i.e. myogenic o Muscle contracts in regular rhythm o Does not fatigue or require rest (unlike skeleatl muscle) o Specialised striated muscle (fainter striations compared to skeletal muscle) o Fibres are branched and uninucleated o Cardiac muscle cells interconnect resulting in simultaneously contraction o Contraction speed = intermediate [compared to skeletal (rapid) and smooth (slow)] o Length of contraction = intermediate [compared to skeletal (short) and smooth (long)] o Cardiomyocytes (cardiac muscle cells) supplied with oxygen & glucose by coronary artery if it becomes blocked -> heart attack

Answer 3

 Carries oxygenated blood from LV to the body  At high pressure (as it has to force the blood over a large distance hence overall there is a higher resitance within the blood vessels)  Largest artery

Answer 4

 Contract to generate a force to move blood at low pressure into the ventricles  Pressure is low as walls of atria are thin (less cardiac muscle)  LA: forces oxygenated blood into LV (short distance so low pressure)  RA forces deoxygenated blood into RV (short distance so low pressure)  Both atria always contract simultaneously

Answer 5

 Contract to generate a force to move blood at high pressure out of the heart  LV: forces oxygenated blood into aorta at high pressure  Pressure is high as LV wall is the thickest (of all 4 chambers) i.e. most cardiac muscle  RV: forces deoxygenated blood into pulmonary artery at lower pressure than LV (if it was the same the pressure would be too high when it reaches the avleoli and would rupture the alveoli)  Both ventricles always contract simultaneously

Answer 6

= semi-lunar valve * found between the LV and the aorta * prevents backflow of blood from aorta to LV during ventricular diastole

Answer 7

= semi-lunar valve * found between the RV and the pulmonary artery * prevents backflow of blood from pulmonary to RV during ventricular diastole

Answer 8

Bucuspid Tricuspid ## Footnote REMEMBER: LAB RAT (LA = bicuspid, RA = tricupsid)

Answer 9

* Located between RA and RV * Prevents backflow of blood from RV to RA during ventricular systole * Close when pressure of RV > pressure of RA * Ensures deoxygenated blood flows into pulmonary artery

Answer 10

* Located between LA and LV * Prevents backflow of blood from LV to LA during ventricular systole * Close when pressure of LV > pressure of LA * Ensures oxygenated blood flows into aorta

Answer 11

 Separates RHS from LHS of heart  Keeps oxygenated blood separated from deoxygeanted blood

Answer 12

 Carries deoxygenated blood from the body to the RA  Superior vena cava delivers deoxygenated blood from head  Inferior vena cava delivers deoxygenated blood from rest of body  Largest vein

Answer 13

 Only open one way  Prevent the back flow of blood  Will open when the pressure behind of it is greater than the pressure in front of it  Will close when the pressure in front of it is greater than the pressure of blood behind it  Blood flows down pressure gradient (from high pressure to low pressure)

Answer 14

* Ventricles relax (ventricular diastole) * Atrial walls contract -> decreases volume of blood & increases pressure in atria * Atria are emptied -> blood forced into ventricles * Through atrioventricular valves (remember LAB RAT) * Slight increase in ventricular volume & pressure as ventricles fill with blood

Answer 15

* Atria relax (pressure falls) * Ventricle walls contract -> decreases volume of blood * Pressure in ventricles rises for ~0.1s * Pressure in ventricles -> pressure in atria atrioventricular valves are forced shut * High pressure in V opens semi-lunar valves (aortic or pulmonary) * Blood is forced into aorta (from LV) or pulmonary artery (from RV) * Pressure & volume of blood in V decreases

Answer 16

* Both atria and ventricles relax (muscular walls of both A and V relax) * Higher pressure in pulmonary artery & aorta  closes semi-lunar valves (preventing backflow of blood into V) * Atria fill with blood (increasing their pressure) due to higher pressure in the vena cava and pulmonary vein * Ventricles continue to relax  ventricular pressure

Answer 17

Lub = atrioventricular valves closing as V contract Dub = semi-lunar valves closing from backflow of blood (from aorta and pulmonary artery) as V relax

Answer 18

no nerve stimulation required to make the cardiac muscles contract ## Footnote remember: only cardiac muscle is myogenic

Answer 19

1. Wave of electrical excitation starts in sino-atrial node (specialised patch of muscle found in the wall of the right atrium); SAN = pacemaker 2. Impulse passes from SAN to atrial muscle 3. Causes atria to contract together i.e. initiates heartbeat 4. Layer of non-conducting collagen (fibrous) tissue between atria and ventricles prevents wave of excitation passing directly to ventricles 5. Electrical activity of SAN is picked up by atrio-ventricular node (AVN) in the septum between the atria 6. AVN delays electrical activity by 0.1s 7. Electrical activity is sent from AVN to Bundle of His (specialised conducting muscle fibres made up of Purkyne fibres) 8. Electrical activity spreads from the Bundle of His down 2 branches of the Purkyne fibres in the septum 9. Electrical activity arrives at apex of the heart 10. At apex Purkyne fibres spread out through both ventricle walls 11. Wave of excitation triggers simultaneous contraction of ventricles starting at the apex (to allow more efficient emptying of ventricles) i.e. ventricular systole occurs from the bottom of the heart upwards

Answer 20

If both ventricles contracted at the same time: o The V would generate a higher pressure than the A o This would force the A-V valves to shut o Blood in the A would consequently NOT enter the V o Blood would be forced back into the veins o This would place strain on the heart o And decrease the volume of blood moved through the heart o Hence less blood would be oxygenated o Poorer transport system and gas exchange

Answer 21

1) accelerator nerve (sympathetic nervous system) 2) vagus nerve (parasympathetic nervous system)

Answer 22

(vagus nerve) * is part of the parasympathetic nervous system * this nerve uses acetylcholine as the neurotransmitter * it decreases the HR

Answer 23

accelerator nerve * is part of the sympathetic nervous system * this nerve uses noradrenaline as neurotransmitter * it increases the HR

Answer 24

Adrenaline

Answer 25

CO = SV x HR units = cm3 min-1 ## Footnote remember the '3' and '-1' are superscript - It won;t let me do that here :(

Answer 26

Less likely to get a counting error in shorter time period Less likely to be affected by fluctations due to envoironmental disturbances Hence value is more accurate

Answer 27

1. If the resting heart rate is to be determined, you must have been resting for at least 10 minutes. The exercise heart rate is obtained while you are exercising 2. The patient must be in the sitting position 3. To measure the pulse at the wrist, place the index and middle finger over the underside of the opposite wrist, below the base of the thumb 4. Press firmly with flat fingers until you feel the pulse. To measure the pulse on the temple, place the index and middle finger just to the side of the head, in the soft, hollow area of the temple (where the temporal artery is positioned). Press firmly until the pulse is located 5. Once you find the pulse, count the beats for 10 seconds, or for 30 seconds and multiply by 6 or 2 accordingly (to calculate beats per minute) 6. Repeat 3 times and take a MEAN (increases reliability) ## Footnote REMEMBER: use the term mean (not average)

Answer 28

* Skeletal muscles contract at high**er** rate * Hence high**er** demand for oxygen & glucose * Hence volume of blood being circulated needs to **increase **dramatically * Hence HR and SV both increase (HR from 72 to 140bpm & SV from 70 to 150cm3 per beat) * Heart muscle also contracts **more** strongly -> great**er** contraction -> great**er** force of ejection * Skeletal muscles also contract **more** frequently -> veins compressed **more** by skeletal muscles -> greater venous return (to remove lactic acid, carbon dioxide, heat from contracting muscles) ## Footnote Remember: your answer must be comparative. This means you must say highER, greatER, MORE throughout your answer

Answer 29

1. Age = children have higher HR than adults (HR decreases with age) 2. Genetics = tendency for lower/higher HR inherited 3. Diseases = some affect HR e.g. CF increases HR (and pulmonary blood pressure)

Answer 30

1. Physical activity level = increased PAL -> inc HR for duration of exercise & straight after (but over time leads to decreased HR). Training decreases resting HR (due to increased SV and so same CO is achieved at lower HR) 2. Smoking = nicotine -> inc HR (as stimulates release of neurotransmitter noradrenaline -> increases electrical activity of SAN) 3. Diet = diet rich in fruit & veg & CBH -> dec HR; diets rich in saturated lipids -> inc HR

Answer 31

* ECGs measure spread of electrical excitation through heart * Process = electrocardiography * ECGs don't directly measure electrical activity of the heart but measures small electrical differences in skin which occur as a result of the electrical activity of the heart * Results can be monitored on computer screen or printed out * Changes in peaks can be used to detect and diagnose heart conditions

Answer 32

Level of risk = very low/none * Because this procedure merely monitors the electrical impulses and does not emit electricity * Hence no risk of shock * During an exercise electrocardiogram, some patients experience arrhythmias or heart distress

Answer 33

## Footnote Make sure you have both a label AND an annotation for each area of the ECG

Answer 34

wave of excitation passing over atria walls (i.e. depolarisation of atria resulting in atria contraction)

Answer 35

repolarisation (recovery) of ventricles (recovery of the atria is masked by QRS)

Answer 36

wave of excitation passing over ventricles walls (i.e. depolarisation of ventricles)

Answer 37

T to Q reason: ventricles are relaxed

Answer 38

The height of any wave indicates how much electrical charge is passing through the heart: bigger wave = more electrical charge = stronger contraction

Answer 39

Ventricular fibrillation reason: there is no regular pattern to ECG

Answer 40

Atrial fibrillation Reasons: There is no distinct P waves *The P-R interval is not easily identifiable

Answer 41

* Victim has no blood circulation * Usually unconscious * Almost certainly fatal: causes cardiac arrest * The person having VF suddenly collapses or falls unconscious, because the brain and muscles have stopped receiving blood from the heart

Answer 42

* Immediate use of defibrillator * May need coronary bypass surgery * Most common complication of VF is sudden death * For survivors of VF, complications include coma, reduced mental acuity, and neurological problems similar to those seen after a stroke

Answer 43

* Muscle in ventricle walls flutter * Possibly due to myocardial infarction

Answer 44

* Most common cause = abnormalities or damage to the heart's structure * High blood pressure * Heart attacks * Coronary artery disease * Abnormal heart valves * Congenital heart defects you're born with * Hyperthyroidism

Answer 45

* Medication to prevent a stroke * Medication to control the heart rate or rhythm * Cardioversion – where the heart is given a controlled electric shock to restore normal rhythm ## Footnote NB: AF is not usually life-threatening

Answer 46

* Increased risk of stroke * Increased risk of heart failure * Chronic fatigue * Additional heart rhythm problems * Inconsistent blood supply

Answer 47

Bradycardia * Resting HR is very slow * Longer gaps between QRS complexes * P waves and height of QRS peaks are both similar to a normal trace * Defined as resting HR between 40-60 bpm * ECG looks normal except delay between waves of more than one second * Long gap between T wave and next P wave

Answer 48

* Usually no effect * If severe may cause tiredness * Due to insufficient blood flow to organs

Answer 49

* Could be the sign of an active/healthy person * Could be an inactive SAN

Answer 50

* Artificial pacemaker to replace SAN

Answer 51

Tachycardia * Resting HR is very high * Shorter gaps between QRS complexes * Defined as resting HR above 100bpm * ECG shows very small gap between T wave and P wave of next cardiac cycle

Answer 52

* A reaction to certain medications * Congenital (present at birth) electrical pathway abnormalities in the heart * Congenital abnormalities of the heart * Consuming excess alcohol * coronary artery disease (atherosclerosis), heart valve disease, heart failure, heart muscle disease (cardiomyopathy), tumours, or infections * Hypertension * Hyperthyroidism (overactive thyroid gland) * Smoking * Certain lung diseases

Answer 53

* Rapid HR = less time for the atria and ventricles to fill * Hence less blood is pumped to the body with each heartbeat * Overtime  drop in blood pressure * Also increases the workload of the heart  increasing myocardial (heart muscle) O2 demand

Answer 54

* Varies depending on what caused the condition, the patient's age and general health, and other factors * Aim = address the cause of the tachycardia * May try to slow the rate i.e. prevent subsequent episodes of tachycardia to reduce risk complications

Answer 55

* Myocardial infarction * Peaks and troughs of ECG are less distinct and not as regular * S-T portion is higher than normal (ST elevation)

Answer 56

* Leads to the formation of a blood clot (coronary thrombosis) * Blood supply to part of heart muscle is partly or full blocked * Cardiac muscle cells deprived of oxygen * Cardiac cells stop contracting

Answer 57

* Aspirin * Thrombolytics * Anticoagulants

Answer 58

* Aspirin: stops blood from clotting * Nitro-glycerine: dilates blood vessels * Pain relieve: relieve pain and is often given intravenously

Answer 59

* Thrombolytics: break up clots. Most effective when taken within 2 hours of the heart attack and are not given after 12 hours have elapsed. These drugs may be given with other anticoagulants (blood thinners)

Answer 60

* Anticoagulants: make blood less likely to form clots e.g. heparin

Answer 61

An occlusion of coronary artery following the rupture of an atherosclerotic plaque

Answer 62

 Apply two electrode pads to chest  Pads placed in diagonal line across chest with heart position in the middle  Reading on machine shows if heart is fibrillating  If it is then AED applies electrical discharge (“electrical shock”)  This stops the chaotic electrical activity of fibrillation & allows heart to restore regular rhythm determined by SAN

Answer 63

 Use an automated external defibrillator (AED)  AED = safe, portable electrical device  AED helps to establish a regular heartbeat during a cardiac arrest by monitoring the person's heartbeat and giving them an electric shock if necessary

Answer 64

 Supply of blood to region of cardiac muscle is disrupted  Area of cardiac muscle does not receive sufficient oxygen  Cardiac muscle in atrial or ventricular walls contract rapidly & irregularly  Ventricles do not fill fully (as no ventricular diastole to allow filling)  Blood isn’t pumped out of ventricles  Patient stops breathing due to lack of oxygen supply

Answer 65

* Check airway and for breathing by tilting head back * Carry out chest compressions (on adult) * Place the heel of your hand on the sternum at the centre of the person's chest * Place your other hand on top of your other hand and interlock your fingers * Using your body weight, keep your elbows locked straight & press straight down vertically (using your body weight) * Press down firmly & quickly by 4-5cm then relax * After each compression release all pressure on the person’s chest without losing contact between the hands and sternum * Aim to do the chest compressions at a rate of 100-120 compressions a minute * Repeat x30 then give mouth-to-mouth resuscitation (expired air resuscitation) twice * Repeat this on 30:2 ratio until an ambulance arrives

Answer 66

o they appear not to be breathing o they're not moving o they don't respond to any stimulation; such as being touched or spoken to

Answer 67

 chest pain – a sensation of heavy crushing pressure, tightness or squeezing in the centre of the chest  pain in other parts of the body – it can feel as if the pain is travelling from the chest to the arms (usually the left arm is affected, but it can affect both arms), jaw, neck, back and abdomen  feeling lightheaded or dizzy  profuse sweating  shortness of breath  cold ashen-looking skin and blue lips  rapid, weak pulse which may be irregular  feeling sick (nausea) or being sick (vomiting)  an overwhelming sense of anxiety (similar to having a panic attack)  coughing or wheezing  unexpected collapse