the heart and monitoring functions.

Question 1

Need for mass transport systems in multicellular organisms (4)

Answer 1

Multicellular organisms:
1. Have higher demand for nutrients and greater production of waste.
2. Have higher metabolic rate.
3. More active organisms -> larger no. of cells respiring very quickly -> greater glucose + O2 demand and CO2 production.
4. SA:VOL too low for diffusion to deliver nutrients at appropriate rate nor remove waste at a suitable rate.

Question 2

What kind of muscle is the heart made up of? (1)

Answer 2

1. Cardiac muscle.

Question 3

What is special about the cardiac muscle? (7)

Answer 3

1. Myogenic -> Does not require nerve stimulation to contract.
2. Contracts in regular rhythm.
3. Does not fatigue or require rest.
4. Specialised striated muscle.
5. Fibres are branched and uni-nucleated.
6. Cardiac muscles interconnect resulting in simultaneous contractions.
7. Cardiomyocytes (cardiac muscle cells) are supplied with O2 and glucose by coronary artery.

Question 4

What happens if the coronary artery becomes blocked? (1)

Answer 4

1. Myocardial infarction.

Question 5

Where are the carotid arteries found? (1)

Answer 5

1. Neck.

Question 6

What is the function of the carotid arteries?

Answer 6

1. To carry oxygen-rich blood to the head, brain, and face.

Question 7

What is the function of the aorta? (3)

Answer 7

1. Carry oxygenated blood to the LV of the body.
2. At high pressure -> Blood needs to be forced over a large distance -> Hence higher resistnance within the blood vessels.
3. Largest artery in the human body.

Question 8

What is the function of the pulmonary artery? (1)

Answer 8

1. Carry deoxygenated blood from left ventricle (LV) to the lungs.

Question 9

What is the function of the pulmonary vein? (1)

Answer 9

1. Carry oxygenated vlood from the lungs to the left artrium (LA).

Question 10

What is the function of the atria? (4)

Answer 10

1. Contract to generate a force to move blood at low pressure into the ventricles -> Low pressure as walls of atria are thin (less cardiac muscle).
2. Left atrium -> forces oxygenated blood into left ventricle (short distance so low pressure).
3. Right atrium -> forces deoxygenated blood into right ventricle (short distance so low pressure).
4. Both atria always contract simultaneously.

Question 11

What is the function of the ventricle? (4).

Answer 11

1. Contract to generate a force to move blood at high pressure out of the heart.
2. Left ventricle -> forces oxygenated blood into aorta at high pressure -> Left ventricle wall is the thickest -> Can handle high pressure -> contains most cardiac muscle.
3. Right ventricle -> forces deoxygenated blood into pulmonary artery at lower pressure than left ventricle.
4. Both ventricles always contract simultaneously.

Question 12

Why doesn’t the right ventricle force deoxygenated blood into the pulmonary artery as the same pressure as the left ventricle? (1)

Answer 12

1. Pressure of blood would be too high when it reaches the alveoli and would rupture the alveoli.

Question 13

Where are semi-lunar valves located? (1)

Answer 13

1. Within the main blood vessels, within the heart.

Question 14

Name the two types of semi-lunar valves? (2)

Answer 14

1. Aortic valve.
2. Pulmonary valve.

Question 15

Where is the aortic valve found? (1)

Answer 15

1. Between the left ventricle and the aorta.

Question 16

What is the function of the aortic valve? (1)

Answer 16

1. Prevent the backflow of blood from aorta to the left ventricle during ventricular systole.

Question 17

Where is the pulmonary valve found? (1)

Answer 17

1. Between the right ventricle and the pulmonary artery.

Question 18

What is the function of the pulmonary valve?

Answer 18

1. Prevent backflow of blood from pulmonary artery to the right ventricle during ventricular diastole.

Question 19

Where are the ventricular valves found? (1)

Answer 19

1. Between the chambers of the heart -> between the atria and the ventricles.

Question 20

Name the two different types of atrioventricular valves. (2)

Answer 20

1. Tricuspid - RAT - Right atrioventricular valve.
2. Bisucpid - LAB - Left Atrioventricular valve.

Question 21

Where is the tricuspid (RAT) found? (1)

Answer 21

1. Between right atrium and the right ventricle.

Question 22

Where is the bicuspid (BAT) found? (1)

Answer 22

1. Left atrium and the left ventricle.

Question 23

What is the function of the tricuspid valve? (3)

Answer 23

1. Prevent backflow of blood from right ventricle to the right atrium during ventricular systole.
2. Close when pressure of right ventricle is greater than pressure of right atrium.
3. Ensures that deoxygenated blood flows into pulmonary artery.

Question 24

What is the function of the Biscuspid valve? (3)

Answer 24

1. Prevent backflow of blood from left ventricle to the left atrium during ventricular systole.
2. Closes when pressure of left ventricle is greater than the pressure of left atrium.
3. Ensures that oxygenated blood flows into aorta.

Question 25

What is the function of the septum? (2)

Answer 25

1. Separates the RHS of the heart from the LHS. 2. Keeps oxygenated blood separated from deoxygenated blood.

Question 26

What is the function of the vena cava? (4)

Answer 26

1. Carry deoxygenated blood from the body to the right atrium. 2. Superior vena cava delivers deoxygenated blood from the head. 3. Inferior vena cava delivers deoxygenated blood from the rest of the body. 4. Largest vein in the human body.

Question 27

What is the function of the chordae tendae?

Answer 27

1. Hold valves in place. 2. Attaches valves to muslce walls of the ventricle. 3. Prevents valves inverting when under pressure -> ventricular systole.

Question 28

What is the function of valves in general?

Answer 28

1. They only open one way -> prevents backflow of blood. 2. Open -> Pressure behind the valve is greater than the pressure in front of it. 3. Close -> PRessure in front is greater than the pressure behind it. 4. Blood flows down pressure gradient -> From higher pressure to lower pressure.

Question 29

Name the 4 different types of tissue found in the heart? (4)

Answer 29

1. SAN (Sino-Atrial Node). 2. AVN (Atrio-Ventricular Node). 3. Bundle of His. 4. Purkinje/ Purkyne Tissue.

Question 30

What does cardiac cycle mean? (1)

Answer 30

1. Events in a single heartbeat - 0.8 seconds in human adult.

Question 31

SAN - Sino-atrial node? (5)

Answer 31

1. Found in the right atrium. 2. Known as pacemaker. 3. Controls contraction of heart muscle. 4. Initiates impulses across atria. 5. Causes atrial systole.

Question 32

AVN - Atrio-ventricular node? (6)

Answer 32

1. Found in septum. 2. Between two atria. 3. Receives impulses from the SAN. 4. Delays impulse. 5. Allows time for atria to empty. 6. passes impulse to ventricles.

Question 33

Bundle of His? (4)

Answer 33

1. Found in septum. 2. Between ventricles. 3. Conductile fibre. 4. Pass impulse down the septum to apex.

Question 34

Purkinje Tissue?

Answer 34

1. Found in ventricles. 2. Carries impulse from apex through ventricular walls. 3. Causes ventricular systole.

Question 35

Differences between diastole and systole? (5) (5)

Answer 35

Diastole: 1. Heart relaxes. 2. Atria + ventricles fill with blood. 3. Volume of blood increases. 4. Pressure of blood increases. 5. Pressure of blood at a minimum in the arteries. Systole: 1. Heart contracts - atria first then ventricles. 2. Atria + ventricles empty of blood. 3. Volume of blood decreases at the end of systole. 4. Pressure of blood increases dramatically for 0.1 seconds then decreases at the end of systole. 5. Pressure of blood at its maximum at the end of systole in the arteries.

Question 36

Events in one cardiac cycle. (atrial systole, ventricular systole, and ventricular + atrial diastole)

Answer 36

Atrial systole: 1. Ventricles are relaxed. 2. Atrial walls contract -> decreases volume of blood + increases pressure in the atria. 3. Atria are emptied -> Blood forced into ventricles through atrioventricular valves. 4. Slight increase in ventricular volume + pressure as ventricles fill with blood. Ventricular systole: 1. Atria relax -> Pressure decreases. 2. Ventricle walls contract -> Decreases volume of blood + pressure in ventricles rises for 0.1seconds. 3. Pressure in ventricles > pressure in atria - atrioventricular valves closed shut. 4. Semi-lunar valves open -> Higher pressure in the ventricles. 5. Blood is forced into aorta (left ventricle) or pulmonery artery (right ventricle). 6. Pressure + volume of blood in ventricles decreases. Ventricular and atrial diastole. 1. Both atria's and ventricular's muscular walls relax. 2. Higher pressure in pulmonary artery + aorta -> closes semi-lunar valves -> Prevent backflow of blood into ventricles. 3. Atria fill with blood -> Increases their pressure -> Due to higher pressure in the vena cava and pulmonary vein. 4. Ventricles continue to relax -> Ventricular pressure < pressure in atria -> Atrioventricular valves open and blood flows into ventricles passively -> No contraction of atrium required.

Question 37

LUB sound? (1)

Answer 37

1. Atrioventricular valves closing as ventricles contract.

Question 38

DUB sound? (1)

Answer 38

Semi-lunar valves closing from backflow of blood from aorta and pulmonary artery as ventricles relax.

Question 39

Controlling heart rate?

Answer 39

1. Cardiac muscle -> myogenic therefore no nerve simulation required. 2. Cardiac muscle contracts spontaneously. 3. Intrinsic heart rate - 60bpm. 4. Resting heart rate - 70bpm.

Question 40

Initation of intrinsic heart rate.

Answer 40

1. Wave of electrical excitation starts in sino-atrial node (SAN). 2. Impulses passs from SAN to atrial muscle. 3. Causes atria to contract together -> 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 for 0.1 seconds. 7. Electrical activity is sent from AVN to Bundle of His. 8. Electrical activity spreads from the Bundle of His down 2 branches of the Purkinje fibres in the septum. 9. Electrical activity arrives at apex of the heart. 10. At apex, Purkinje fibres spread out through ventricular walls. 11. Wave of excitation triggers simultaneous contraction of ventricles starting at the apex -> Allows more efficient emptying of ventricles -> Ventricular systole occurs from the bottom of the heart upwards.

Question 41

What would happen if the atria and ventricles contracted at the same time?

Answer 41

1. Ventricles would generate a higher pressure than the atria. 2. Forcing atrioventricular valves shut. 3. Blood in the atria would consequently not enter the ventricles. 4. Blood forced back into veins. 5. Placing strain on the heart. 6. Decreasing the volume of blood moved through the heart. 7. Less blood would be oxygenated. 8. Poorer transport system + gas exchange.

Question 42

Nerves regulating the heart rate. (4)

Answer 42

Accelerator nerve (sympathetic nervous system). 1. Noradrenaline as the neurotransmitter to increase the HR. Vagus nerve (sympathetic nervous system). 2. Acetylcholine as the neurotransmitter to decrease the HR.

Question 43

Name three neurotransmitters regulating heart rate. (3)

Answer 43

1. Acetylcholine. 2. Noradrenaline. 3. Adrenaline.

Question 44

Stroke volume?

Answer 44

1. Volume of blood pumped out of the left ventricle during each cardiac cycle (60-80cm^3)

Question 45

Cardiac output?

Answer 45

1. Volume of blood pumped out of the left ventricle each minute.

Question 46

Equation for Cardiac output? (2)

Answer 46

SV x HR units: cm^3 min^-1

Question 47

What is pulse?

Answer 47

Distention of artery wall as blood surges through artery with ventricular systole, followed by elastic recoil of artery wall during ventricular diastole.

Question 48

Measuring pulse rate? (7)

Answer 48

1. Count no. of beats in an artery in 30 seconds -> double -> less prone to counting errors -> more accurate. Different places to measure: 2. Radial artery (wrist). 3. Femoral artery (groin). 4. Temporal artery (temples). 5. Carotid artery (neck). 6 Need to use place where artery is close to the surface of the skin and passes over bone. 7. Quick, easy, little equipment and skill needed procedure.

Question 49

HR during strenuous exercise? (6)

Answer 49

1. Skeletal muscles contract at higher rate. 2. Hence higher demand for oxygen and glucose. 3. Hence volume of blood being circulated needs to increase dramatically. 4. Hence HR and stroke volume both increase (HR from 72 to 140bpm + SV from 70-150cm^3 per beat). 5. Hence muscles also contract more strongly -> greater contraction -> greater force of ejection. 6. Skeletal muscles also contract more frequently -> veins compressed more by skeletal muscles -> greater venous return -> to remove lactic acid, CO2, heat from contracting muscles.

Question 50

Natural factors affecting HR? (3)

Answer 50

1. Age - children have higher HR than adults as HR decreases with age. 2. Genetics - tendency for lower or higher HR. 3. Diseases - some affect HR - Cystic Fibrosis increases HR and pulmonary blood pressure.

Question 51

Life-style factors affecting HR? (3)

Answer 51

1. Physical activity level (PAL) - Increased PAL -> Increased HR for duration of exercise and straight after -> But overtime leads to decreased HR. Training decreases resting HR -> Due to increased SV and so same cardiac output is achieved at a lower HR. 2. Smoking -> nicotine -> Increased HR -> Stimulates release of neurotransmitter noradrenaline -> Increases electrical activity of SAN. 3. Diet -> Diet rich in fruit + vegs + CBH -> Decreases HR -> But diet rich in saturated lipids -> Increased HR.

Question 52

P-wave? (1)

Answer 52

1. Wave of excitation passing over atria wall - depolarisation of atria resulting in atria contraction due to SAN triggering.

Question 53

QRS complex? (1)

Answer 53

1. Wave of excitation passing over ventricle walls - depolarisation of ventricles - triggering main pumping contractions.

Question 54

T-wave? (1)

Answer 54

1. Repolarisation of ventricles (recovery) - recovery of atria is masked by QRS.

Question 55

ST segment? (1)

Answer 55

1. Beginning of ventricle repolarisation - should be flat.

Question 56

PR interval? (1)

Answer 56

1. Delay of AVN to allow filling of ventricles.

Question 57

Q -> T? (1)

Answer 57

1. Contraction time.

Question 58

T -> Q? (1)

Answer 58

1. Filling time (ventricles are relaxed).

Question 59

Ventricular Fibrillation (VF)? (5)

Answer 59

1. ECG feature - no regular pattern. 2. Caused by muscle in ventricle walls flutter + possibly due to myocardial infarction. 3. Effect: Victim has no blood circulation, usually unconscious, certainly fatal -> causes cardiac arrest, person having VF suddenly collapses or falls unconscious -> brain + muscles have stopped receiving blood from the heart. 4. Treatment: Immediate use of defibrillator, may need coronary bypass surgery. 5. Complications: Coma, reduced mental acuity, and neurological problems similar to those seen after a stroke.

Question 60

Atrial Fibrillation (AF)? (4)

Answer 60

1. ECG: Muscle walls of atria contract arrhythmically (abnormal + irregular rhythm), preventing efficient ventricular filling, NO DISTINCT P WAVE, PR INTERVAL NOT EASILY IDENTIFIABLE. 2. Cause: abnormalities or damage to the heart's structure -> High BP, myocardial infarction, coronary heart disease, abnormal heart valves, congenital heart defects you're born with, hyperthyroidism. 3. Effect: Increased risk of strokes, heart failure, chronic fatigue, additional heart rhythm problems, inconsistent blood supply. 4. Treatment: Uncomfortable - but not life threatening. Medication to prevent strokes + control the heart rate or rhythm. Cardioversion -> Giving the heart a controlled electric shock to restore normal rhythm.

Question 61

Bradycardia - B for below normal HR. (4)

Answer 61

1. ECG - Resting HR very slow, LONGER GAPS BETWEEN QRS COMPLEXES, BUT P-WAVE AND HEIGHT OF QRS IS SIMILAR TO THAT OF A NORMAL TRACE, LONGER GAP BETWEEN T WAVE AND THE NEXT P WAVE. Resting heart rate defined as 40-60bpm. 2. Cause: Sign of an active + healthy person, or an inactive SAN. 3. Effect: Usually no effect, may cause severe tiredness -> insufficient blood flow to organs. 4. Treatment: Artifical pacemaker to replace SAN.

Question 62

Tachycardia - T for normal HR is Too low. (4)

Answer 62

1. ECG: Resting HR is very high, SHORTER GAPS BETWEEN QRS COMPLEXES, resting heart defined as above 100bpm, VERY SMALL GAP BETWEEN T-WAVE AND THE NEXT P-WAVE. 2. Cause: Reaction to certain medications, congenital electrical pathway abnormality in the heart, congenital abnormalities of the heart, consuming excess alcohol, coronary heart disease, heart valve disease, heart failure, heart muscle disease (cardiomyopathy), tumours, or infections, hypertension, hyperthyroidism, smoking, certain lung diseases. 3. Effect: Rapid HR -> less time for atria and ventricles to fill -> less blood pumped to the body with each heartbeat -> overtime BP decreases -> workload of heart increases -> increasing myocardial O2 demand. 4. Treatment: Varies on cause, patient's age and general health, aim is to address cause of T, may try slowing the HR -> prevent subsequent episodes of T to reduce risk of complications.

Question 63

Myocardial Infarction? (4)

Answer 63

1. ECG: PEAKS AND TROUGHS ARE LESS DISTINCT AND IRREGULAR, S-T ELEVATION. 2. Cause: Occlusion of coronary artery following the rupture of an atherosclerotic plaque. 3. Effect: Formation of blood clot (coronary thrombosis), blood supply to that part of the heart is partially or fully blocked, cardiac muscle cells deprived of O2, cardiac cells stop contracting. 4. Treatment: Aspirin -> stops blood clotting. Thrombolytics -> break up clots. Anticoagulants -> Make blood less likely to form clots (heparin). Pain relief -> Relieve pain (given intravenously), Nitro-glycerine -> Dilate blood vessels.

Question 64

Recognising a heart attack. (12)

Answer 64

1. Chest pain - sensation of heavy crushing pressure, tightness or squeezing in the centre of the chest. 2. Pain in other parts of the body - feels as if pain is travelling from the chest to the arms (usually left arm), jaw, neck, back, and abdomen. 3. Feeling lightheaded and dizzy. 4. Profuse sweating. 5. Shortness of breath. 6. Cold ashen-looking skin + blue lips. 7. Rapid, weak pulse -> irregular. 8. Feeling nauseous or being sick (vomiting). 9. Overwhelming sense of anxiety (similar to a panic attack). 10. Coughing or wheezing. 11. Unexpected collapse. 12. Impending sense of doom.

Question 65

Events during a cardiac arrest? (6)

Answer 65

1. Supply of blood to region of cardiac muscle is disrupted. 2. Area of cardiac muscle does not receive sufficient oxygen. 3. Cardiac muscle in atrial or ventricular walls contract rapidly + irregularly. 4. Ventricles do not fill fully (no ventricular diastole to allow filling). 5. Blood isn't pumped out of the ventricles. 6. Patient stops breathing due to lack of oxygen supply.

Question 66

Recognising cardiac arrest?

Answer 66

1. Person appears to not be breathing. 2. Person not moving. 3. Person not responding to any stimulation -> such as being touched or spoken to.