The heart Flashcards
Main points
Actual pumping is by activity of cardiac muscle which only constitutes …..% the weight of the heart ……..g (300g total weight of heart).
Heart lies in the middle of the ……. between the …….. rib & ……… inter-costal space (12-14 cm height); because of the larger mass of the left ventricle two-thirds of the mass is on left hand side.
The region where the ……. blood vessels leave the heart is termed the …….., whereas the tip of the ventricles is known as the ……..
The Apex of the heart touches the rib cage between ….. & ….. ribs just below left nipple and this known as the point of maximal intensity.
Actual pumping is by activity of cardiac muscle which only constitutes 50% the weight of the heart 150g (300g total weight of heart).
Heart lies in the middle of the thorax between the 2nd rib & 5th inter-costal space (12-14 cm height); because of the larger mass of the left ventricle two-thirds of the mass is on left hand side.
The region where the large blood vessels leave the heart is termed the BASE, whereas the tip of the ventricles is known as the APEX.
The Apex of the heart touches the rib cage between 5th & 6th ribs just below left nipple and this known as the point of maximal intensity.
Pericardium
The heart lies in a conical double-walled fibro-serous sac, the pericardium.
This tough, dense connective tissue layer protects the heart and …….. it to surrounding structures, such as the diaphragm, …….., and the great vessels that issue from the heart.
It consists of an inner …….. membrane and an outer ……. layer.
The inner serous pericardium is composed of two smooth layers, the …….l and …….. layers, one attached to the heart and the other to the fibrous sac.
The heart lies in a conical double-walled fibro-serous sac, the pericardium.
This tough, dense connective tissue layer protects the heart and anchors it to surrounding structures, such as the diaphragm, sternum, and the great vessels that issue from the heart.
It consists of an inner serous membrane and an outer fibrous layer.
The inner serous pericardium is composed of two smooth layers, the visceral and parietal layers, one attached to the heart and the other to the fibrous sac.
Functions of the Pericardium
The two smooth layers allow the heart to beat in the thorax with the minimum of ……..
The ……….. sets the limit to the ………… size of the ……….. of the heart and prevents excessive stretching of the cardiac muscle fibres due to ………… with blood.
- The pericardium is attached to the diaphragm, and when the heart beats, it behaves as if the ……. were relatively fixed. Thus when the ventricles contract, instead of the apex moving upwards towards the base, the base, and particularly the arterio-ventricular ………, ………. towards the apex. This has the effect of increasing the ……. of the atria at the same time as blood is ejected from the ventricles. This decreases ……….. of blood flow into the …… and helps to pull the blood from the two circulations into their respective atria.
The two smooth layers allow the heart to beat in the thorax with the minimum of friction.
The pericardium sets the limit to the maximum size of the chambers of the heart and prevents excessive stretching of the cardiac muscle fibres due to overfilling with blood.
- The pericardium is attached to the diaphragm, and when the heart beats, it behaves as if the apex were relatively fixed. Thus when the ventricles contract, instead of the apex moving upwards towards the base, the base, and particularly the arterio-ventricular ring, descends towards the apex. This has the effect of increasing the size of the atria at the same time as blood is ejected from the ventricles. This decreases resistance of blood flow into the atria and helps to pull the blood from the two circulations into their respective atria.
Pericarditis (causes include infection, diseases of connective tissue or damage due to ……… ………..)
It involves in……….. of the serous pericardium
Also known as ‘pericardial frictional rub’ can be heard through a ste………., similar to the sound of dry dead leaves being crushed in hand, causes enormous pain.
Cardiac tamponade (causes include trauma injuries) A potentially fatal condition in which a large ........ of fluid or blood accumulates in the ............ cavity and com............ the heart from the out...... The heart cannot fill properly and as a consequence, cannot ......... effectively
Pericarditis (causes include infection, diseases of connective tissue or damage due to radiation treatment)
It involves inflammation of the serous pericardium
Also known as ‘pericardial frictional rub’ can be heard through a stethoscope, similar to the sound of dry dead leaves being crushed in hand, causes enormous pain.
Cardiac tamponade (causes include trauma injuries) A potentially fatal condition in which a large volume of fluid or blood accumulates in the pericardial cavity and compresses the heart from the outside The heart cannot fill properly and as a consequence, cannot pump effectively
Heart valves
The valves are placed between at…….. and vent….. andin the bases of the pulmonary artery and the aorta and control the dire….. of blood flow through the heart. The heart valves all lie in the same plane.
There are four:
the tri…….. between right atrium and ventricle,
(b) the pulmonary (semilunar) between ……. ventricle and ………… artery,
(c) the aortic (semilunar) between left ……… and ……….,
(d) mitral (bicuspid) between left …….. and left ………..
The valves are placed between atria and ventricles and in the bases of the pulmonary artery and the aorta and control the direction of blood flow through the heart. The heart valves all lie in the same plane.
There are four:
the tricuspid between right atrium and ventricle,
(b) the pulmonary (semilunar) between right ventricle and pulmonary artery,
(c) the aortic (semilunar) between left ventricle and aorta,
(d) mitral (bicuspid) between left atrium and left ventricle.
Heart valves
Around the entry of superior and inferior vena cavae and the pulmonary veins are rings of cardiac muscle which close off the veins with a sph……..-like action so that blood is not regurgitated back into the ……. when the …….. contract.
The chambers of the heart can work under iso………. conditions if the valves close properly and hence can exert a p……… on the blood.
It is these pressures that determine the opening & closing of the values.
Around the entry of superior and inferior vena cavae and the pulmonary veins are rings of cardiac muscle which close off the veins with a sphincter-like action so that blood is not regurgitated back into the veins when the atria contract.
The chambers of the heart can work under isometric conditions if the valves close properly and hence can exert a pressure on the blood.
It is these pressures that determine the opening & closing of the values.
Heart valve disorders
Most acquired disorders of the heart valves are dege…………
Abnormal heart sounds, or mur…….., may be indicative.
Most important heart valves are the ao…… and mit…/bi……. valves (left ventricle)
These are the most likely to become affected because of the ……. blood pressures in these chambers.
Most acquired disorders of the heart valves are degenerative.
Abnormal heart sounds, or murmurs, may be indicative.
Most important heart valves are the aortic and mitral/bicusbid valves (left ventricle)
These are the most likely to become affected because of the high blood pressures in these chambers.
Categories of heart valve disease
There are two main categories of disease:
INSUFFICIENCY – produced by r………… (backflow of blood through an incompletely closed valve)
STENOSIS (an inc…………. opened valve)
N.B. Either type of malfunction can lead to congestive heart failure.
Categories of heart valve disease
There are two main categories of disease:
INSUFFICIENCY – produced by regurgitation (backflow of blood through an incompletely closed valve)
STENOSIS (an incompletely opened valve)
N.B. Either type of malfunction can lead to congestive heart failure.
Left side of the heart
Mitral insufficiency (blood from the left ventricle flows back into the left ……….. during systole).
Mitral stenosis (…………. of the valve reduces flow from the left atrium to the left ventricle) - is only seen after an attack of rheu……. fever.
Heart can cope with m…………… valve disease relatively ……… and surgical treatment can be put off until the symptoms cannot be controlled by drug treatment.
Mitral valve disease is often accompanied by arrh……. - atrial fib……. - that is usually the result of distension of the left atr…… The accompanying palpitation makes one feel very uncomfortable and while the arrhythmia can be controlled by dig……. treatment, the heart rarely returns to a regular rhythm.
In all cases this leads to increased load on the left ………. and the heart muscle responds by beating more v………. and by over-development (hypertrophy).
Mitral insufficiency (blood from the left ventricle flows back into the left atrium during systole).
Mitral stenosis (narrowing of the valve reduces flow from the left
atrium to the left ventricle) - is only seen after an attack of
rheumatic fever.
Heart can cope with mitral valve disease relatively well and surgical treatment can be put off until the symptoms cannot be controlled by drug treatment.
Mitral valve disease is often accompanied by arrhythmia - atrial fibrillation - that is usually the result of distension of the left atrium. The accompanying palpitation makes one feel very uncomfortable and while the arrhythmia can be controlled by digitoxin treatment, the heart rarely returns to a regular rhythm.
In all cases this leads to increased load on the left ventricle and the heart muscle responds by beating more vigorously and by over-development (hypertrophy).
left side of heart part 2
3 Aortic insufficiency (blood flows back into the left ........ during dia........). 4 Aortic stenosis (pressure in the left ventricle increases in response to a .......... valve opening, and isch........ results because of an insufficient oxy.... supply). This is a common disorder of older men in which the w..... cusps of the valve become thick...... and ri..... with increa..... age. In younger people either cong.....l malformation or rheumatic fever is the cause.
- Eventually however, the heart muscle cannot cope and angina, shortness of breath on exertion, and a tendency to faintness develop.
- At this stage valve replacement is essential for survival because the average time between the onset of ill health caused by aortic ste…. and death is …. years.
- Diuretic drugs, can ease some of the problems but cannot prevent the inevitable decline. Death when it comes is usually s…….. and, as is so often the case in heart disease, at a time when the victim seems to be in good health.
3 Aortic insufficiency (blood flows back into the left ventricle during
diastole).
4
Aortic stenosis (pressure in the left ventricle increases in
response to a narrowed valve opening, and ischaemia results
because of an insufficient oxygen supply). This is a common
disorder of older men in which the worn cusps of the valve become
thickened and rigid with increasing age. In younger people either
congenital malformation or rheumatic fever is the cause.
- Eventually however, the heart muscle cannot cope and angina, shortness of breath on exertion, and a tendency to faintness develop.
- At this stage valve replacement is essential for survival because the average time between the onset of ill health caused by aortic stenosis and death is two years.
- Diuretic drugs, can ease some of the problems but cannot prevent the inevitable decline. Death when it comes is usually sudden and, as is so often the case in heart disease, at a time when the victim seems to be in good health.
Heart valve replacement 1
Mortality rates of aortic valve replacement are around 1% and for mitral valve replacement around 3%, and so surgery is safe and successful
Unfortunately replacement valves are not perfect. The mechanical ones take the form of a sil……. ball (or a tilting disc) in a metal cage and can cause c…… formation so antic……… drugs are essential
Safer drugs such as as….., which merely affect the pl……., are not enough. Warfarin is the most widely used but to ensure the dose is correct a blood test is needed every …. weeks or less. Despite this there is always a risk of bleeding. The risk of serious bleeding has been estimated at 4% per year
Mortality rates of aortic valve replacement are around 1% and for mitral valve replacement around 3%, and so surgery is safe and successful
Unfortunately replacement valves are not perfect. The mechanical ones take the form of a silastic ball (or a tilting disc) in a metal cage and can cause clot formation so anticoagulant drugs are essential
Safer drugs such as aspirin, which merely affect the platelets, are not enough. Warfarin is the most widely used but to ensure the dose is correct a blood test is needed every 6 weeks or less. Despite this there is always a risk of bleeding. The risk of serious bleeding has been estimated at 4% per year
Heart Valve Replacement 2
The alternative substitute is a biological or natural valve, which is usually taken from a …… or sometimes, human donors. After careful preparation these valves can give good service for many years and anticoagulants are …… needed, but do not last forever. A lifespan of ….-…… years seems likely and rather less in young people.
The alternative substitute is a biological or natural valve, which is usually taken from a pig or sometimes, human donors. After careful preparation these valves can give good service for many years and anticoagulants are not needed, but do not last forever. A lifespan of 7-10 years seems likely and rather less in young people.
Other heart valve disorders
Pulmonary insufficiency (blood flows back from the pulmonary …….. into the right ……….. during …….),
(6) Pulmonary stenosis (blood is ……….. from leaving the ……. ventricle, causing ventricular hyper…….. and eventual failure),
(7) Tricuspid insufficiency (blood flows back into the right ……. during ……),
(8) Tricuspid stenosis (blood is …….. from flowing from the ……. atrium to the right ……….).
Pulmonary insufficiency (blood flows back from the pulmonary artery into the right ventricle during diastole),
(6) Pulmonary stenosis (blood is prevented from leaving the right ventricle, causing ventricular hypertrophy and eventual failure),
(7) Tricuspid insufficiency (blood flows back into the right atrium during systole),
(8) Tricuspid stenosis (blood is obstructed from flowing from the right atrium to the right ventricle).
Nodal Tissue 1
The heart is capable of beating independently of any outside influence and possesses auto……………., due to the presence of specialised tissue known as …… tissue
Nodal tissue is derived from cardiac muscle but has lost its ability to ……… and has developed powers of spontaneous dep………… and cond……….
Nodal tissue exists as a series of discrete masses, bundles or …….. within the ………
The sinoatrial (SA) node acts as the pacemaker for the heartbeat, because it spontaneously …………… most rapidly of all parts of the nodal tissue. Basic rhythm is about ….. depolarisations per minute, but the rate can be altered by ner….. or che…… factors
The heart is capable of beating independently of any outside influence and possesses autorhythmicity, due to the presence of specialised tissue known as nodal tissue
Nodal tissue is derived from cardiac muscle but has lost its ability to contract and has developed powers of spontaneous depolarisation and conductivity
Nodal tissue exists as a series of discrete masses, bundles or fibres within the heart
The sinoatrial (SA) node acts as the pacemaker for the heartbeat, because it spontaneously depolarises most rapidly of all parts of the nodal tissue. Basic rhythm is about 80 depolarisations per minute, but the rate can be altered by nervous or chemical factors
Nodal Tissue 2
Spontaneous depolarisation due to s……… ion leakage through the membranes of nodal tissue. The permeability to p…….. ions is l….. than found in n….cells but the permeability to sodium is gr……. than in ……….. cells.
NB. This leakage can occur in any part of the nodal tissue but is most rapid in the ..... node.
Action potentials produced by the SA node are transmitted to muscle cells of the atria and pass through these cells de………….. them and causing their contra……. Speed through atrial muscle is approximately 0. ….. m/sec.
Spontaneous depolarisation due to sodium ion leakage through the membranes of nodal tissue. The permeability to potassium ions is less than found in nerve cells but the permeability to sodium is greater than in nerve cells.
NB. This leakage can occur in any part of the nodal tissue but is most rapid in the SA node.
Action potentials produced by the SA node are transmitted to muscle cells of the atria and pass through these cells depolarising them and causing their contraction. Speed through atrial muscle is approximately 0.3 m/sec.
