Chapter 5 Heart & monitoring heart function Flashcards
What is the need for a mass transport system in multicellular organisms?
Due to higher demand for nutrients and greater production of waste from a higher metabolic rate and activity level.
What is the general structure of the heart?
The heart acts as 2 pumps separated by a septum.
What is the function of the left side of the heart?
Pumps oxygenated blood to the rest of the body.
What is the function of the right side of the heart?
Pumps deoxygenated blood to the lungs.
What type of muscle is cardiac muscle?
Specialised striated muscle that does not require nerve stimulation to contract (myogenic).
What is the contraction speed of cardiac muscle compared to skeletal and smooth muscle?
Intermediate.
What do the carotid arteries do?
Carry oxygen-rich blood to the head, brain, and face.
What is the role of the aorta?
Carries oxygenated blood from the left ventricle to the body at high pressure.
What does the pulmonary artery do?
Carries deoxygenated blood from the right ventricle to the lungs.
What is the function of the pulmonary vein?
Carries oxygenated blood from the lungs to the left atrium.
What is the role of the atria in the heart?
Contract to generate a force to move blood at low pressure into the ventricles.
What differentiates the left ventricle from the right ventricle?
The left ventricle has the thickest wall and pumps oxygenated blood into the aorta at high pressure.
What prevents backflow of blood from the aorta to the left ventricle?
Aortic valve.
What prevents backflow of blood from the pulmonary artery to the right ventricle?
Pulmonary valve.
What separates the right and left sides of the heart?
Septum.
What is the function of the vena cava?
Carries deoxygenated blood from the body to the right atrium.
What do chordae tendinae do?
Hold valves in place and prevent them from inverting during pressure changes.
What is the cardiac cycle?
The events in a single heartbeat, approximately 0.8 seconds long in humans.
What happens during diastole?
The heart relaxes and fills with blood.
What occurs during ventricular systole?
Ventricles contract and eject blood into the pulmonary artery and aorta.
What are the heart sounds ‘lub’ and ‘dub’ associated with?
‘Lub’ = atrioventricular valves closing; ‘Dub’ = semilunar valves closing.
What initiates the wave of electrical excitation in the heart?
Sino-atrial node (SAN).
What is the role of the atrio-ventricular node (AVN)?
Delays electrical activity to ensure atria have stopped contracting before ventricles contract.
What is stroke volume?
Volume of blood pumped out of the left ventricle during each cardiac cycle (approximately 60-80 cm³).
What is the formula for cardiac output?
CO = SV x HR.
What factors affect heart rate?
- Age
- Genetics
- Diseases
- Physical activity level
- Smoking
- Diet
What is the significance of the SAN being myogenic?
It does not require input from the brain to initiate the heartbeat.
What happens if both ventricles contract simultaneously?
It would cause backflow of blood into the atria, decreasing the volume of blood moved through the heart.
What is the purpose of measuring pulse rate?
To assess heart rate and cardiovascular health.
How can standard deviation (SD) be used in data processing?
To assess the reliability of the data.
What does a smaller standard deviation indicate?
More reliable data set.
What does it mean to reject the null hypothesis in a t-test?
There is a significant difference between the mean values of two groups.
What is the formula to determine degrees of freedom for a paired t-test?
Paired t-test DoF = number of pairs of data - 1
What is the formula to determine degrees of freedom for an unpaired t-test?
Unpaired t-test DoF = (n1 + n2) - 2
At the 95% confidence level, what decision is made if tcalculated > tcritical?
Reject the null hypothesis
At the 95% confidence level, what decision is made if tcalculated < tcritical?
Accept the null hypothesis
What do ECGs measure?
Spread of electrical excitation through the heart
What is the process called that measures electrical activity of the heart?
Electrocardiography
Does an ECG directly measure electrical activity of the heart?
No, it measures small electrical differences in skin due to heart activity
What can changes in peaks of an ECG be used to detect?
Heart conditions
Are there any risks associated with ECG procedures?
Generally, there are no risks
What might some patients experience during an exercise electrocardiogram?
Arrhythmias or heart distress
What is ventricular fibrillation (VF)?
No regular pattern to ECG; muscle in ventricle walls flutter
What is the most common cause of ventricular fibrillation?
Myocardial infarction
What is the effect of ventricular fibrillation on a victim?
No blood circulation; usually unconscious; almost certainly fatal
What is the immediate treatment for ventricular fibrillation?
Use of a defibrillator
What characterizes atrial fibrillation (AF) on an ECG?
Muscle walls of atria contract arrhythmically, no distinct P waves
What is the most common cause of atrial fibrillation?
Abnormalities or damage to the heart’s structure
What are some effects of atrial fibrillation?
- Increased risk of stroke
- Increased risk of heart failure
- Chronic fatigue
What defines bradycardia in terms of resting heart rate?
Resting HR between 40-60 bpm
What are the ECG features of bradycardia?
Longer gaps between QRS complexes; ECG looks normal except delay
What is the treatment for severe bradycardia?
Artificial pacemaker
What defines tachycardia in terms of resting heart rate?
Resting HR above 100 bpm
What are the ECG features of tachycardia?
Shorter gaps between QRS complexes
What is the most common cause of myocardial infarction?
Occlusion of coronary artery following rupture of atherosclerotic plaque
What are some symptoms of a heart attack?
- Chest pain
- Pain in other parts of the body
- Shortness of breath
What should you do first if you suspect someone is having a heart attack?
Call 999
What is the CPR compression rate for adults?
100-120 compressions a minute
What is the purpose of an automated external defibrillator (AED)?
Helps to establish a regular heartbeat during a cardiac arrest
What do you do if an AED indicates the heart is fibrillating?
AED applies electrical discharge to stop fibrillation
