CVS Overview Flashcards
What is the circulatory system?
- Organ system transporting oxygen, carbon dioxide, nutrients etc around the body
What are the different components of the CVS?
- Heart
- Blood vessels (arteries, veins, capillaries)
- Blood
- Lymphatic system
What is the pulmonary circulation?
- Oxygen depleted blood
- Passes from heart to lungs
- Return oxygenated blood to the heart
What is the systemic circulation?
- Oxygen rich blood
- Passes from heart to rest of the body
- Return deoxygenated blood to heart
What is the mediastinum?
Everything in the chest apart from the lungs
What are the 4 parts of the mediastinum?
- Superior
- Middle
- Anterior
- Posterior
What is the tough fibrous tissue that surrounds the heart?
Pericardium
Where is the fluid between the outer layer and inner layer of pericardial tissue found in?
The pericardial cavity
What is the middle layer of tissue around the heart called?
Myocardium (muscle)
What is the inner layer of the tissue around the heart called?
Endocardium
What will drain into the superior vena cava?
Anything above the level of the heart
What will drain into the inferior vena cava?
Anything below the level of the heart
What does the pulmonary trunk do?
Splits into right and left pulmonary artery - takes deoxygenated blood away from heart to lungs
What is the ductus venosus?
- Found in the foetal circulation
- Diverts blood away from the liver
- Takes about 50% of mothers blood away from the liver
What is the foramen ovale?
- Hole in the foetus which bypasses the lungs
- Takes blood straight from the right atrium to the left atrium
Why does the clinical team want to hear a baby cry when it is delivered?
As the ductus venosus immediately closes so air goes into the lungs - large amount of blood goes into left side of the heart and the foramen ovale closes
What blood vessels supply blood to the heart tissue?
Coronary arteries
What are trabeculae carinae inside the heart?
Muscular, columnar protrusions found on the inside surface of the ventricles, the main pumping chambers of the heart. It is thought that they help prevent suction that would occur with a smooth surface. Some trabeculae also act as a type of connective tissue, to help bind the hearts muscle together
What are chordae tendinea?
Heart strings - hold things down in place so valve doesn’t pop up backwards
What are the possible septal defects of the heart?
- Interventricular/ interatrial septum (septum = a wall or partition dividing a body space or cavity)
- ‘hole in the heart’
- Atrial septal defect
- Ventricular septal defect
- Atrioventricular septal defect
What is a ‘hole in the heart’?
A defect of the heart in which there is an abnormal opening in any of the walls dividing the 4 heart chambers
What can cause an atrial septal defect?
- Incomplete closure of the foramen ovale
- So hole in the heart - blood goes from left side into right side and puts right side of the heart into increased pressure so doesn’t pump as effectively as it should
- Larger defects result in hypertrophy of the RA and RV
What is hypertrophy?
Enlargement of a tissue or organ entirely by enlargement of existing cells
What category of the population tend to have more problems with heart defects?
People with down syndrome
What is the name for the right atrioventricular valve?
Tricuspid valve
What is the name for the left atrioventricular valve?
Bicuspid valve
What are the names of the valves that are not the bi or tricuspid valves?
The semilunar valves
What are the 2 sounds of the heart?
- Lub
- Dub
What is the ‘lub’ sound of the heart?
- Loud noise due to the closure of the atrioventricular valves at the time of VENTRICULAR SYSTOLE
What is the ‘dub’ sound of the heart?
- Softer sound due to the closure of the semilunar valves at the time of ATRIAL SYSTOLE
What is the process of blood flow in the heart through the different chambers?
- Blood returning to the heart fills atria, putting pressure against the atrioventricular valves; which forces the valves open
- As ventricles fill, atrioventricular valve flaps hand limply into ventricles
- Atria contract, forcing additional blood into ventricles
- Then the ventricles contract, forcing blood against the atrioventricular valve cusps
- Atrioventricular valves close
- Papillary muscles contract and chordae tendineae tighten, preventing valve flaps from entering into atria
- As ventricles contract and interventricular pressure rises, blood is pushed up against semilunar valves, forcing them open
- As ventricles relax and interventricular pressure falls, blood flows back from arteries, filling the cusps of the semilunar valves and forcing them to close
What is infective endocarditis?
The inner layer of the heart becoming infected/inflamed
What is the most common form of infective endocarditis?
Subacute bacterial endocarditis
Where does subacute bacterial endocarditis occur?
On the rheumatic or congenitally abnormal valves (have to give antibiotics before any dental procedure)
What can subacute bacterial endocarditis affect?
Prosthetic valves
What can cause subacute bacterial endocarditis?
- Many organisms e.g. Streptococcus viridans/ Staphylococcus aureus
- Can be a result of a dental abscess
What can also be present if a patient is suffering from subacute bacterial endocarditis?
A murmur can be present due to valvular vegetations (Vegetation = a blood clot initiated by infection of the structure involved)
What does the L and R coronary artery supply?
Supply blood to the heart
What are the veins that drain the blood from the heart?
- Small cardiac vein
- Middle cardiac vein
- Anterior cardiac vein
- Coronary sinus
Coronary arteries are ‘end arteries’. What does this mean?
Arteries that are the only supply of oxygenated blood to a portion of tissue
What is meant by ‘ischaemia’?
- An inadequate blood supply to an organ or part of the body
What is meant by ‘collateral circulation’?
- An accessory blood pathway developed through enlargement of secondary vessels after the obstruction of a main channel
What does ischemia in the heart result in?
Collateral circulation
What is angina pectoris?
Chest pain related to CAD (coronary artery disease) as it is resulting from decreased blood supply to the heart muscle (ischaemia)
What is infarction?
- Death of tissue (worst case scenario)
- L coronary artery tends to be more affected:
- Anterior IV branch of LCA (40%-50%)
- RCA (30%-40%)
- Circumflex branch of LCA (15%-20%)
What are the different types of coronary artery bypasses?
- Internal mammary artery bypass
- Saphenous vein bypass
What is used in a saphenous vein bypass?
Longest vein in the body which runs from ankle to groin
- Can be used for people that require more than one or two bypasses
What are Purkinje fibres?
Specialised muscle fibres found in the heart. They originate at the atrioventricular bundle and extend into the ventricles. Their function is to relay impulses from the bundle to the ventricles, causing a contraction
What is atrial fibrillation?
- Rapid, irregular contraction of different parts of the atria
What is ventricular fibrillation?
- Rapid, irregular contraction of the ventricles
- Not compatible with systemic and coronary circulation
- Most disorganised form of dysrhythmia, and leads to cardiac arrest
What is a dysrhythmia?
Rhythm isn’t normal - abnormal cardiac rhythm
What does systole mean?
Contraction
What does diastole mean?
Relaxation
What does systole cause?
Expansion of atrial walls
What maintains arterial blood pressure during diastole?
Recoil
What are the 3 layers of blood vessels?
- Tunica intima: Intimately associated with blood and fluid (variable thickness)
- Tunica media: elastic muscle fibres
- Tunica adventitia: Outer layer of blood vessels
What are examples of elastic arteries?
- Aorta
- Common carotid
- Subclavian
- Pulmonary arteries
What are examples of muscular arteries?
- Radial
- Femoral
- Coronary
- Cerebral
What are arterioles?
- Terminal branches supplying capillary bed
What Is the venous system?
- Low pressure collecting system (less elastic and muscle fibres)
- Passive movement down a pressure gradient (has to get shoved along)
- Negative pressure in chest on inspiration
What does skeletal muscle act as in venous system of the lower limbs?
A muscular pump
What is resent in the veins of the lower limbs to prevent backflow of blood?
Valves
