the heart and monitoring functions. Flashcards
Need for mass transport systems in multicellular organisms (4)
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.
What kind of muscle is the heart made up of? (1)
- Cardiac muscle.
What is special about the cardiac muscle? (7)
- Myogenic -> Does not require nerve stimulation to contract.
- Contracts in regular rhythm.
- Does not fatigue or require rest.
- Specialised striated muscle.
- Fibres are branched and uni-nucleated.
- Cardiac muscles interconnect resulting in simultaneous contractions.
- Cardiomyocytes (cardiac muscle cells) are supplied with O2 and glucose by coronary artery.
What happens if the coronary artery becomes blocked? (1)
- Myocardial infarction.
Where are the carotid arteries found? (1)
- Neck.
What is the function of the carotid arteries?
- To carry oxygen-rich blood to the head, brain, and face.
What is the function of the aorta? (3)
- Carry oxygenated blood to the LV of the body.
- At high pressure -> Blood needs to be forced over a large distance -> Hence higher resistnance within the blood vessels.
- Largest artery in the human body.
What is the function of the pulmonary artery? (1)
- Carry deoxygenated blood from left ventricle (LV) to the lungs.
What is the function of the pulmonary vein? (1)
- Carry oxygenated vlood from the lungs to the left artrium (LA).
What is the function of the atria? (4)
- 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).
- Left atrium -> forces oxygenated blood into left ventricle (short distance so low pressure).
- Right atrium -> forces deoxygenated blood into right ventricle (short distance so low pressure).
- Both atria always contract simultaneously.
What is the function of the ventricle? (4).
- Contract to generate a force to move blood at high pressure out of the heart.
- Left ventricle -> forces oxygenated blood into aorta at high pressure -> Left ventricle wall is the thickest -> Can handle high pressure -> contains most cardiac muscle.
- Right ventricle -> forces deoxygenated blood into pulmonary artery at lower pressure than left ventricle.
- Both ventricles always contract simultaneously.
Why doesn’t the right ventricle force deoxygenated blood into the pulmonary artery as the same pressure as the left ventricle? (1)
- Pressure of blood would be too high when it reaches the alveoli and would rupture the alveoli.
Where are semi-lunar valves located? (1)
- Within the main blood vessels, within the heart.
Name the two types of semi-lunar valves? (2)
- Aortic valve.
- Pulmonary valve.
Where is the aortic valve found? (1)
- Between the left ventricle and the aorta.
What is the function of the aortic valve? (1)
- Prevent the backflow of blood from aorta to the left ventricle during ventricular systole.
Where is the pulmonary valve found? (1)
- Between the right ventricle and the pulmonary artery.
What is the function of the pulmonary valve?
- Prevent backflow of blood from pulmonary artery to the right ventricle during ventricular diastole.
Where are the ventricular valves found? (1)
- Between the chambers of the heart -> between the atria and the ventricles.
Name the two different types of atrioventricular valves. (2)
- Tricuspid - RAT - Right atrioventricular valve.
- Bisucpid - LAB - Left Atrioventricular valve.
Where is the tricuspid (RAT) found? (1)
- Between right atrium and the right ventricle.
Where is the bicuspid (BAT) found? (1)
- Left atrium and the left ventricle.
What is the function of the tricuspid valve? (3)
- Prevent backflow of blood from right ventricle to the right atrium during ventricular systole.
- Close when pressure of right ventricle is greater than pressure of right atrium.
- Ensures that deoxygenated blood flows into pulmonary artery.
What is the function of the Biscuspid valve? (3)
- Prevent backflow of blood from left ventricle to the left atrium during ventricular systole.
- Closes when pressure of left ventricle is greater than the pressure of left atrium.
- Ensures that oxygenated blood flows into aorta.
What is the function of the septum? (2)
- Separates the RHS of the heart from the LHS.
- Keeps oxygenated blood separated from deoxygenated blood.
What is the function of the vena cava? (4)
- Carry deoxygenated blood from the body to the right atrium.
- Superior vena cava delivers deoxygenated blood from the head.
- Inferior vena cava delivers deoxygenated blood from the rest of the body.
- Largest vein in the human body.
What is the function of the chordae tendae?
- Hold valves in place.
- Attaches valves to muslce walls of the ventricle.
- Prevents valves inverting when under pressure -> ventricular systole.
What is the function of valves in general?
- They only open one way -> prevents backflow of blood.
- Open -> Pressure behind the valve is greater than the pressure in front of it.
- Close -> PRessure in front is greater than the pressure behind it.
- Blood flows down pressure gradient -> From higher pressure to lower pressure.
Name the 4 different types of tissue found in the heart? (4)
- SAN (Sino-Atrial Node).
- AVN (Atrio-Ventricular Node).
- Bundle of His.
- Purkinje/ Purkyne Tissue.
What does cardiac cycle mean? (1)
- Events in a single heartbeat - 0.8 seconds in human adult.
SAN - Sino-atrial node? (5)
- Found in the right atrium.
- Known as pacemaker.
- Controls contraction of heart muscle.
- Initiates impulses across atria.
- Causes atrial systole.
AVN - Atrio-ventricular node? (6)
- Found in septum.
- Between two atria.
- Receives impulses from the SAN.
- Delays impulse.
- Allows time for atria to empty.
- passes impulse to ventricles.
Bundle of His? (4)
- Found in septum.
- Between ventricles.
- Conductile fibre.
- Pass impulse down the septum to apex.
Purkinje Tissue?
- Found in ventricles.
- Carries impulse from apex through ventricular walls.
- Causes ventricular systole.
Differences between diastole and systole? (5) (5)
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.
Events in one cardiac cycle. (atrial systole, ventricular systole, and ventricular + atrial diastole)
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.
LUB sound? (1)
- Atrioventricular valves closing as ventricles contract.
DUB sound? (1)
Semi-lunar valves closing from backflow of blood from aorta and pulmonary artery as ventricles relax.
Controlling heart rate?
- Cardiac muscle -> myogenic therefore no nerve simulation required.
- Cardiac muscle contracts spontaneously.
- Intrinsic heart rate - 60bpm.
- Resting heart rate - 70bpm.
Initation of intrinsic heart rate.
- Wave of electrical excitation starts in sino-atrial node (SAN).
- Impulses passs from SAN to atrial muscle.
- Causes atria to contract together -> Initiates heartbeat.
- Layer of non-conducting collagen (fibrous) tissue between atria and ventricles prevents wave of excitation passing directly to ventricles.
- Electrical activity of SAN is picked up by atrio-ventricular node (AVN) in the septum between the atria.
- AVN delays electrical activity for 0.1 seconds.
- Electrical activity is sent from AVN to Bundle of His.
- Electrical activity spreads from the Bundle of His down 2 branches of the Purkinje fibres in the septum.
- Electrical activity arrives at apex of the heart.
- At apex, Purkinje fibres spread out through ventricular walls.
- 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.
What would happen if the atria and ventricles contracted at the same time?
- Ventricles would generate a higher pressure than the atria.
- Forcing atrioventricular valves shut.
- Blood in the atria would consequently not enter the ventricles.
- Blood forced back into veins.
- Placing strain on the heart.
- Decreasing the volume of blood moved through the heart.
- Less blood would be oxygenated.
- Poorer transport system + gas exchange.
Nerves regulating the heart rate. (4)
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.
Name three neurotransmitters regulating heart rate. (3)
- Acetylcholine.
- Noradrenaline.
- Adrenaline.
Stroke volume?
- Volume of blood pumped out of the left ventricle during each cardiac cycle (60-80cm^3)
Cardiac output?
- Volume of blood pumped out of the left ventricle each minute.
Equation for Cardiac output? (2)
SV x HR
units: cm^3 min^-1
What is pulse?
Distention of artery wall as blood surges through artery with ventricular systole, followed by elastic recoil of artery wall during ventricular diastole.
Measuring pulse rate? (7)
- Count no. of beats in an artery in 30 seconds -> double -> less prone to counting errors -> more accurate.
Different places to measure: - Radial artery (wrist).
- Femoral artery (groin).
- Temporal artery (temples).
- Carotid artery (neck).
6 Need to use place where artery is close to the surface of the skin and passes over bone. - Quick, easy, little equipment and skill needed procedure.
HR during strenuous exercise? (6)
- Skeletal muscles contract at higher rate.
- Hence higher demand for oxygen and glucose.
- Hence volume of blood being circulated needs to increase dramatically.
- Hence HR and stroke volume both increase (HR from 72 to 140bpm + SV from 70-150cm^3 per beat).
- Hence muscles also contract more strongly -> greater contraction -> greater force of ejection.
- Skeletal muscles also contract more frequently -> veins compressed more by skeletal muscles -> greater venous return -> to remove lactic acid, CO2, heat from contracting muscles.
Natural factors affecting HR? (3)
- Age - children have higher HR than adults as HR decreases with age.
- Genetics - tendency for lower or higher HR.
- Diseases - some affect HR - Cystic Fibrosis increases HR and pulmonary blood pressure.
Life-style factors affecting HR? (3)
- 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.
- Smoking -> nicotine -> Increased HR -> Stimulates release of neurotransmitter noradrenaline -> Increases electrical activity of SAN.
- Diet -> Diet rich in fruit + vegs + CBH -> Decreases HR -> But diet rich in saturated lipids -> Increased HR.
P-wave? (1)
- Wave of excitation passing over atria wall - depolarisation of atria resulting in atria contraction due to SAN triggering.
QRS complex? (1)
- Wave of excitation passing over ventricle walls - depolarisation of ventricles - triggering main pumping contractions.
T-wave? (1)
- Repolarisation of ventricles (recovery) - recovery of atria is masked by QRS.
ST segment? (1)
- Beginning of ventricle repolarisation - should be flat.
PR interval? (1)
- Delay of AVN to allow filling of ventricles.
Q -> T? (1)
- Contraction time.
T -> Q? (1)
- Filling time (ventricles are relaxed).
Ventricular Fibrillation (VF)? (5)
- ECG feature - no regular pattern.
- Caused by muscle in ventricle walls flutter + possibly due to myocardial infarction.
- 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.
- Treatment: Immediate use of defibrillator, may need coronary bypass surgery.
- Complications: Coma, reduced mental acuity, and neurological problems similar to those seen after a stroke.
Atrial Fibrillation (AF)? (4)
- ECG: Muscle walls of atria contract arrhythmically (abnormal + irregular rhythm), preventing efficient ventricular filling, NO DISTINCT P WAVE, PR INTERVAL NOT EASILY IDENTIFIABLE.
- 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.
- Effect: Increased risk of strokes, heart failure, chronic fatigue, additional heart rhythm problems, inconsistent blood supply.
- 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.
Bradycardia - B for below normal HR. (4)
- 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.
- Cause: Sign of an active + healthy person, or an inactive SAN.
- Effect: Usually no effect, may cause severe tiredness -> insufficient blood flow to organs.
- Treatment: Artifical pacemaker to replace SAN.
Tachycardia - T for normal HR is Too low. (4)
- 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.
- 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.
- 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.
- 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.
Myocardial Infarction? (4)
- ECG: PEAKS AND TROUGHS ARE LESS DISTINCT AND IRREGULAR, S-T ELEVATION.
- Cause: Occlusion of coronary artery following the rupture of an atherosclerotic plaque.
- 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.
- 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.
Recognising a heart attack. (12)
- Chest pain - sensation of heavy crushing pressure, tightness or squeezing in the centre of the chest.
- 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.
- Feeling lightheaded and dizzy.
- Profuse sweating.
- Shortness of breath.
- Cold ashen-looking skin + blue lips.
- Rapid, weak pulse -> irregular.
- Feeling nauseous or being sick (vomiting).
- Overwhelming sense of anxiety (similar to a panic attack).
- Coughing or wheezing.
- Unexpected collapse.
- Impending sense of doom.
Events during a cardiac arrest? (6)
- 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 (no ventricular diastole to allow filling).
- Blood isn’t pumped out of the ventricles.
- Patient stops breathing due to lack of oxygen supply.
Recognising cardiac arrest?
- Person appears to not be breathing.
- Person not moving.
- Person not responding to any stimulation -> such as being touched or spoken to.
