Chapter 5: Heart & Monitoring Heart Function
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- Created by: Malaika
- Created on: 22-12-20 13:58
Why do multicellular organisms need a mass transport system?
Low surface area:volume ratio
high metabolic rate
metabolic processes cannot be fulfilled by diffusion only
high metabolic rate
metabolic processes cannot be fulfilled by diffusion only
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Why can simple, single-celled organisms rely on simple diffusion only?
Large surface area:volume ratio
low metabolic rate
metabolic processes can be fulfilled by diffusion only
low metabolic rate
metabolic processes can be fulfilled by diffusion only
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Function: Carotid arteries
blood vessels that carry oxygen-rich blood to head, brain and face
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Function: Aorta
Carries oxygenated blood from left ventricle to body
at a high pressure
largest artery
at a high pressure
largest artery
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Function: Pulmonary Artery
Carries deoxygenated blood from right ventricle to lungs
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Function: Pulmonary Vein
Carries oxygenated blood from lungs to left atrium
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Function: Atria
Contract to generate a force to move blood at low pressure
thin walls
Right and left atria contract simultaneously
thin walls
Right and left atria contract simultaneously
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Function: Ventricles
Contract to generate a force to move blood at high pressure
thick walls
right and left ventricles contract simultaneously
thick walls
right and left ventricles contract simultaneously
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Function: Aortic (semilunar) valve
found between left ventricle and aorta
prevents backflow of blood from aorta to left ventricle during ventricular diastole
prevents backflow of blood from aorta to left ventricle during ventricular diastole
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Function: Pulmonary (semilunar) valve
found between right ventricle and pulmonary artery
prevents backflow of blood from pulmonary artery to right ventricle during ventricular diastole
prevents backflow of blood from pulmonary artery to right ventricle during ventricular diastole
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Function: Tricuspid (atrioventricular) valve
located between right atrium and right ventricle
prevents backflow of blood dyring ventricular systole
closes when pressure of RV>RA
prevents backflow of blood dyring ventricular systole
closes when pressure of RV>RA
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Function: Bicuspid (atrioventricular) valve
located between left atrium and left ventricle
prevents backflow of blood during ventricular systole
closes when pressure of LV>LA
prevents backflow of blood during ventricular systole
closes when pressure of LV>LA
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Function: Septum
separates right hand side of heart from left hand side
keeps oxygenated and deoxygenated blood separate
keeps oxygenated and deoxygenated blood separate
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Function: Vena Cava
carries deoxygenated blood from body to right atrium
superior - from head
inferior - from body
largest vein
superior - from head
inferior - from body
largest vein
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Function: Chordae Tendinae
holds valves in place
attaches valves to muscle wall of ventricles
prevents valves inverting during ventricular systole
attaches valves to muscle wall of ventricles
prevents valves inverting during ventricular systole
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Definition: cardiac cycle
events in a single heartbeat (~0.8s)
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What happens during atrial systole (and ventricular diastole)?
ventricles relax
atrial walls contract - blood volume decreases and pressure increases
atria are emptied through atrioventricular valves
ventricles fill with blood - slight increase in ventricular volume and pressure
atrial walls contract - blood volume decreases and pressure increases
atria are emptied through atrioventricular valves
ventricles fill with blood - slight increase in ventricular volume and pressure
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What happens during ventricular systole (and atria diastole)?
atria relax
ventricle walls contract - blood volume decreases
ventricular pressure rises for ~0.1s
ventricles emptied through semilunar valves
blood pressure and volume in ventricles decreases
ventricle walls contract - blood volume decreases
ventricular pressure rises for ~0.1s
ventricles emptied through semilunar valves
blood pressure and volume in ventricles decreases
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What happens during diastole?
all 4 chambers relax
semilunar valves close
atria fill with blood (ventricles continue to relax)
semilunar valves close
atria fill with blood (ventricles continue to relax)
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What are the 'lub-dub' sounds?
Lub = atrioventricular valves closing as ventricles contract
Dub = semilunar valve closing from backflow of blood as ventricles relax.
Dub = semilunar valve closing from backflow of blood as ventricles relax.
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Resting hear rate of adult
~70bpm
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Why is it important that the ventricles contract after the atria?
ventricles would generate a higher pressure than atria
av valves would shut
blood would not flow from atria to ventricles
blood would be forced back into veins
poor transport system and gas exchange
av valves would shut
blood would not flow from atria to ventricles
blood would be forced back into veins
poor transport system and gas exchange
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Why is the SAN called the natural pacemaker?
it initiates and controls rhythm of the heartbeat
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Which two nerves regulate heart rate?
Accelerator nerve (sympathetic nervous system)
Vagus nerve (parasympathetic nervous system)
Vagus nerve (parasympathetic nervous system)
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What does the accelerator nerve do?
Increases heart rate
uses noradrenaline as neurotransmitter
uses noradrenaline as neurotransmitter
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What does the vagus nerve?
decreases heart rate
uses acetylcholine as neurotransmitter
uses acetylcholine as neurotransmitter
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Definition: stroke volume
volume of blood pumped out of left ventricle during each cardiac cycle (~60-80cm3)
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Definition: cardiac output
volume of blood pumped out of left ventricle each minute (cm3min-1)
stroke volume x heart rate
stroke volume x heart rate
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Definition: heart rate
number of beats per minute (~72bpm)
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Method: measuring pulse rate at rest
1) ensure patient is resting (sitting) for at least 10 mins
2) place firmly index and middle finger on one of the relevant arteries
3) Once pulse is found, count beats for 30s and multiply by 2
4) repeat 3 times to take average (increases reliability)
2) place firmly index and middle finger on one of the relevant arteries
3) Once pulse is found, count beats for 30s and multiply by 2
4) repeat 3 times to take average (increases reliability)
30 of 70
4 places to measure pulse rate
Radial artery (wrist)
Femoral artery (groin)
Carotid artery (neck)
Temporal artery (temples)
Femoral artery (groin)
Carotid artery (neck)
Temporal artery (temples)
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3 natural factors affecting heart rate
Age
Genetics
Diseases
Genetics
Diseases
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Does heart rate increase or decrease with age?
Decrease
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3 lifestyle factors affecting heart rate
Physical Activity Level
Smoking
Diet
Smoking
Diet
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How does training affect resting heart rate?
It decrease heart rate due to increase stroke volume and so cardiac output is achieved at lower heart rate
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How does smoking affect heart rate?
nicotine increases heart rate as it stimulates the release of noradrenaline which increases electrical activity of SAN
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How does a diet rich in fruits, veg and carbohydrates affect heart rate?
Decreases heart rate
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What does ECG stand for?
Electrocardiogram
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What does an ECG measure?
the spread of electrical excitation through heart
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Risks of ECGs
generally no risks
because procedure monitors electrical impulses but doesn't emit electricity so no risk of shock
because procedure monitors electrical impulses but doesn't emit electricity so no risk of shock
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What is the p-wave on an ECG?
wave of excitation passing over atria walls
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What is the QRS on an ECG?
wave of excitation passing over ventricle walls
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What is the T-wave on an ECG?
repolarisation (recovery) of ventricles
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What does the height of a wave on an ECG indicate?
how much electrical charge is passing through the heart
bigger wave = more electrical charge = stronger contraction
bigger wave = more electrical charge = stronger contraction
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ECG features of atrial fibrillation?
no regular pattern
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Causes of ventricular fibrillation?
muscle in ventricle walls flutter due to myocardial infarction
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Effect of ventricular fibrillation?
patient has no blood circulation
usually unconscious
causes cardiac arrest
patient suddenly collapses due to brain and muscles not receiving blood from heart
usually unconscious
causes cardiac arrest
patient suddenly collapses due to brain and muscles not receiving blood from heart
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Treatment of ventricular fibrillation?
immediate use of defibrillator
may need coronary bypass surgery
may need coronary bypass surgery
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Complications of ventricular fibrillation?
most common - sudden death
coma
reduced mental activity
neurological problems
coma
reduced mental activity
neurological problems
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ECG features of atrial fibrillation?
no distinct p waves
P-R interval is not easily identifiable
muscle walls of atria contract arrhythmically
P-R interval is not easily identifiable
muscle walls of atria contract arrhythmically
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Causes of atrial fibrillation?
abnormalities/damage to heart's structure
high blood pressure
heart attacks
coronary artery disease
abnormal heart valves
congenital heart defects
hyperthyroidism
high blood pressure
heart attacks
coronary artery disease
abnormal heart valves
congenital heart defects
hyperthyroidism
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Effect of atrial fibrillation?
increased risk of stroke
increased risk of heart failure
chronic fatigue
additional heart rhythm problems
inconsistent blood supply
increased risk of heart failure
chronic fatigue
additional heart rhythm problems
inconsistent blood supply
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Treatment of atrial fibrillation?
Medication to prevent a stroke
Medication to control heart rate/rhythm
Cardioversion - heart given controlled electric shock to restore normal rhythm
Medication to control heart rate/rhythm
Cardioversion - heart given controlled electric shock to restore normal rhythm
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ECG trace of bradycardia?
very slow resting heart rate (40-60bpm)
delay between waves of more than one second
long gap between T wave and next P wave
delay between waves of more than one second
long gap between T wave and next P wave
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Causes of bradycardia?
sign of active/healthy person
inactive SAN
inactive SAN
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Effects of bradycardia?
usually no effect
if severe, may cause tiredness due to insufficient blood flow to organs
if severe, may cause tiredness due to insufficient blood flow to organs
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Treatment of bradycardia?
artificial pacemaker to replace SAN
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ECG features of tachycardia?
very high resting heart rate (>100bpm)
small gaps between T wave and next P wave
small gaps between T wave and next P wave
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Causes of tachycardia?
reaction to certain medications
congenital electrical pathway abnormalities in heart
consuming excess alcohol
smoking
atherosclerosis, hypertension, hyperthyroidism
certain lung diseases
congenital electrical pathway abnormalities in heart
consuming excess alcohol
smoking
atherosclerosis, hypertension, hyperthyroidism
certain lung diseases
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Effects of tachycardia?
rapid heart rate
so less blood is pumped to body per heartbeat
blood pressure decreases
myocardial oxygen demand increases
so less blood is pumped to body per heartbeat
blood pressure decreases
myocardial oxygen demand increases
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Treatment of bradycardia?
address cause of tachycardia
varies for each patient
try to slow heart rate
varies for each patient
try to slow heart rate
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ECG features of myocardial infarction?
peaks and troughs are less distinct and not as regular
ST elevation
ST elevation
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Causes of myocardial infarction?
occlusion of coronary artery due to rupture of atherosclerotic plaque
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Effect of myocardial infarction?
causes coronary thrombosis (blood clot)
cardiac muscle deprived of oxygen so stops contracting
cardiac muscle deprived of oxygen so stops contracting
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Treatment of myocardial infarction?
aspirin - to prevent blood clotting
nitro-glycerine -dilates blood vessels
pain relief
thrombolytics - break up clots
anticoagulants - reduce likelihood of blood clotting
nitro-glycerine -dilates blood vessels
pain relief
thrombolytics - break up clots
anticoagulants - reduce likelihood of blood clotting
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Signs and symptoms of heart attack
chest pain
radiating pain (usually to left arm)
feeling lightheaded or dizzy
shortness of breath
profuse sweating
blue lips
pale skin
rapid, weak pulse
nausea
unexpected collapse
radiating pain (usually to left arm)
feeling lightheaded or dizzy
shortness of breath
profuse sweating
blue lips
pale skin
rapid, weak pulse
nausea
unexpected collapse
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Heart attack first aid (conscious patient)
Call 999
Sit person in comfortable (W) position
If angina is taken, encourage it
Monitor breathing and pulse until assistance arrives
Sit person in comfortable (W) position
If angina is taken, encourage it
Monitor breathing and pulse until assistance arrives
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Signs of cardiac arrest
Unconsciousness
Patient not breathing
Patient not moving
Patient not responding to stimulation
Patient not breathing
Patient not moving
Patient not responding to stimulation
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Treatment of cardiac arrest
Call 999
Call for help
Perform CPR
Ask someone to get a defib
Use defib by following instructions
Call for help
Perform CPR
Ask someone to get a defib
Use defib by following instructions
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What happens during a cardiac arrest
supply of of blood to cardiac muscle is disrupted
cardiac muscle doesn't receive sufficient blood
cardiac muscle in atria and ventricles contracts irregularly and rapidly
ventricles don't fill fully
blood isn't pumped out of ventricles
patient stops breat
cardiac muscle doesn't receive sufficient blood
cardiac muscle in atria and ventricles contracts irregularly and rapidly
ventricles don't fill fully
blood isn't pumped out of ventricles
patient stops breat
70 of 70
Other cards in this set
Card 2
Front
Why can simple, single-celled organisms rely on simple diffusion only?
Back
Large surface area:volume ratio
low metabolic rate
metabolic processes can be fulfilled by diffusion only
low metabolic rate
metabolic processes can be fulfilled by diffusion only
Card 3
Front
Function: Carotid arteries
Back
Card 4
Front
Function: Aorta
Back
Card 5
Front
Function: Pulmonary Artery
Back
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