The heart 8.5 Flashcards
On which side of the heart would you find oxygenated and deoxygenated blood
- Deoxygenated blood from the body flows into the right side of the heart
- Oxygenated blood from the lungs returns to the left side of the heart from then lungs
what is the destination of the blood after it leaves either side of the heart
the blood from the right side of the heart is pumped to the lungs to become oxygenated
the blood from the left side of the heart is pumped to the rest of the body to provide it with oxygen for respiration
What type of muscle is the heart composed of and what featues does it have
- cardiac muscle
- myogenic (self exciting)
- does not get fatigued
What artery supplies the cardiac muscle with blood
The coronary arteries supply the cardiac muscle with all the oxygenated blood it needs to keep contracting and relaxing all the time
- What surrounds the heart
- what is its function
- inelastic pericardial membranes
- help to prevent heart from over-distending with blood
Name all the parts of the heart
detailed
Explain how the blood makes its way to the lungs through the heart
- blood flows into right atrium via vena cava, blood fills this under low pressure
- pressure builds until blood gos through tricuspid
- right atrium then contracts and right ventricle fills with blood
- right ventricle contracts, tricuspid valve closes (preventing blood flow, tendinous cords prevent inversion)
- blood passes semilunar valve into pulmonary artery where blood is sent to the lungs
Does the artia have thin or thick muscle walls
thin musclar walls
Explain how the blood makes its way from the lungs to the rest of the body through the heart
- oxygenated blood enters left atrium via pulmonary vein
- as pressure builds bicuspid
- when both left atrium and ventricle full atrium contracts forcing blood into left ventricle
- left ventricle then contracts forcing blood through semilunar valve into aorta and around the body
- as ventricle contracts bicuspid valve closes
Which side of the heart has thicker walls and why is it such
- left side of heart has thicker musclar walls as force needed to pump blood around body is greater than just to the lungs
what is the wall that seperates the 2 side of the heart called and what is its function
The septum is the inner dividing wall of the heart which prevents the mixing of deoxygenated and oxygenated blood.
which side of the heart fills up first
The right side and left side of the heart fill and empty together
What does the cardiac cycle describe
The cardiac cycle describes the events in a single heartbeat
What is diastole
the phase of the heartbeat when the heart muscle relaxes and allows the chambers to fill with blood.
what is systole
the phase of the heartbeat when the heart muscle contracts
what occurs during diastole and what are the features of this time
- atrials and ventricles fill with blood
- volume and pressure of blood in the heart build
- pressure in the arteries is at a minimum
what occurs during systole
- blood pressure in arteries is at maximum
- end of systole pressure and volume
- atrials contract, followed by ventricular contraction
what does each line represent on this graph and what does each labelled point represent
What causes the sound of the heartbeat
They are made by blood pressure closing the heart valve
what are the sounds of the heartbeat called
Lub Dub
why is it important that the cardiac muscle is myogenic
it prevents the body wasting resources maintaining the basic heart rate
what things maintains the basic rhythm of the heart
Sino-atrial node
atrio-ventricular node
bundle of His
Purkinje fibres
Explain the process of how the heartbeat is carried out
what is in place to control the process
- sino-atrial node generates wave of electrical excitation, causing atria to contract
- layer of non-conducting tissue stops wave passing to ventricles
- wave is picked up by atria-ventricluar node (AVN)
- AVN causes slight delay before stimulating bundle of His (bundle of purkinje fibres) found in septum
- ^splits into 2 and conductis excitation to the apex of heart
- purkinje fibres found in walls of both ventricles
- causes contraction, which starts at apex so ventricle totally empties
apex = bottom of heart
what would you do to measure the spread of electrical excitation through the heart
ECG (electrocardiogram)
Even though it doesn’t directly measure the electrical activity of your heart, it measures tiny electrical difference in your skin, which results from the electrical activity of the heart
What does this ECG represent
Normal ECG - beats evenly spaced, 60-100/min
What does this ECG represent
bradycardia - slow heart rate - beats evenly spaced, < 60/mim
what does this ECG represent
Tachycardia - fast heart rate - beats evenly spaced, Rate >100/min
what does this ECG represent and what do the labelled parts represent
Ectopic heart beat - altered rhythm, extra beat followed by longer than normal gap before the next beat
what does this ECG represent
Atrial fibrillation - abnormal irregular rhythm from atria, ventricle lose regular rhythm
what is Tachycardia and what can it be caused by
- when heartbeat is very rapid, over 100 bpm
- often normal, for instance when you exercise
- if abnormal can be caused by problems in electrical control of the heart
^treated by medication or by surgery
What is bradycardia and what can it be caused by
When the heart rate slows down to below 60 bpm.
Many people have bradycardia because they are fit - training makes the heart beat more slowly and efficiently. Severe bradycardia can be serious and may need an artificial pacemaker to keep the heart beating steadily
What is an ectopic heartbeat
- Extra heartbeats that are out of the normal rhythm.
- ^normal to have 1 a day
- can be linked to serious conditions if continuous
What is atrial fibrillation
It is an example of an arrhythmia, which means an abnormal rhythm of the heart.
Rapid electrical impulses are generated in the atria. They contract very fast (fibrillate) up to 400 times a minute.
However they don’t contract properly and only some of the impulses are passed onto the ventricles, which contract much less often.
As a result the heart does not pump blood very efficiently
