Cardiology System Intro Flashcards
What is function of CVS?
- Deliver nutrients and oxygen to cells
- Remove waste products from cells
- Maintain constant internal environment (homeostasis)
What does aorta branch into?
Aorta –> smaller arteries –> smaller arterioles –> capillary beds
What happens at capillary beds?
Gas exchange occurs
How do capillary beds turn into veins?
Capillary bed –> venules –> veins –> superior/inferior vena cava
What are the 2 circulations of the CVS?
- System (to and from body)
- Pulmonary (to and from lungs)
What are the 2 functional parts of CVS?
- Conducting
- Exchange
What forms the conducting part of the CVS?
Vasculature (tubes) –> arteries + veins, away and towards heart
What forms the exchange part of the CVS?
Capillary beds (where diffusion occurs). Link smallest arterioles to smallest venules which forms continuous exchange system
What is the valve between the right atrium and right ventricle called?
Right atrioventricular valve –> tricuspid valve
Where does right ventricle eject blood into?
Pulmonary trunk
What does right pulmonary trunk divide into?
Right and left pulmonary artery going towards lungs for reoxygenation
What are the pectinate muscles?
Elevations in the atria walls that are important for contraction of atria. Prevents atria from over distending.
What can the heartbeat be divided into?
- Diastole
- Systole
What is the diastole part of the heartbeat?
Atria and ventricles relax and fill with blood
What is the systole part of the heartbeat?
Atria contract (atrial systole) and push blood into ventricles. As atria start to relax, ventricles contract (ventricular systole) and pump blood out of heart.
How many layers of tissue does the heart consist of? What are they?
3
- Epicardium
- Myocardium
- Endocardium
What is job of epicardium?
Protective layer mostly made of connective tissue
What is job of myocardium?
Muscles of the heart
What is job of endocardium?
Lines the inside of the heart and protects the valves and chambers
How is blood taken back to heart from lungs after reoxygenation?
Via pulmonary veins (to left atrium)
What is the oracle on top of atria?
Extra bit of space to receive extra blood when needed
What is the internal septum?
What is the internal septum?
Prevents blood from mixing by separating right and left atrium (shows atria come from 2 different embryological developments)
What are the Crista terminalis?
Eleveations which separates smooth and rough parts of the atria
What is the fossa ovalis?
Indentation which is important in foetal circulation
What is the coronary sinus?
A collection of veins joined together to form a large vessel that collects blood from myocardium. Delivers deoxy blood to right atrium (along with superior and inferior vena cava)
What are the the chordae tendineae (heart strings)?
Fibrous cords of connective tissue that connect papillary muscles to tricuspid valve and mitral valve in heart
When ventricles contract, chords prevent permeation into atria –> holds leaflets taut during ventricular systole so no backflow
What is function of a heart valve?
Allows blood to flow only in one direction through heart
What are the 4 valves in the heart?
- 2 atrioventricular valves
- 2 semilunar valves
What are the 2 AV valves? Where are they? What is their purpose?
- Mitral valve (bicuspid valve)
- Tricuspid valve
Between the upper chambers (atria) and lower chambers (ventricles). Prevent backflow from ventricles to atria during systole.
What are the SL valves? Where are they?
- Aortic valve
- Pulmonary valve
In arteries leaving the heart
What side are the mitral (bicuspid) and aortic valve on?
Left heart
What side of the heart is the tricuspid and pulmonary valve in?
Right side of heart
What is function of tricuspid valve?
Prevents backflow of blood from right ventricle into right atrium
How many cusps does tricuspid/bicuspid valve have?
Tricuspid –> 3 cusps (anterior, posterior, septal)
Bicuspid –> 2 cusps (anterior, posterior)
How are AV valves anchored to walls of ventricles?
By chordae tendinae
What are the chordinae tendinae attached to?
Papillary muscles
What is the name of the papillary muscles and chordae tendinae together? What is their function?
Subvalvular apparatus –> keep the valves from prolapsing into the atria when they close. BUT have no effect on opening and closing of valves
What is opening and closing of valves caused by?
Pressure gradient across the valve
What is function of mitral valve?
Allows blood to flow from left atrium to left ventricle
What is the ascending aorta?
Portion of the aorta commencing at opening of left ventricle, on a level with the lower border of the 3rd costal cartilage behind the left half of the sternum.
What does ascending aorta branch into?
2 coronary arteries which supply the heart
Where does the left vagus nerve pass?
Anterior to the aortic arch
What are the 4 sections of the aorta?
- Ascending aorta
- Aortic arch
- Thoracic (descending) aorta
- Abdominal aorta
What is the aortic arch?
A continuation of the ascending aorta
What are the 3 main branches of the aortic arch?
- Brachiocephalic trunk
- Left common carotid artery
- Left sublclavian artery
What does brachiocephalic trunk split into? What does this supply?
Ascends laterally to split into the right common carotid artery and right subclavian artery. These supply the right side of the head and neck and the right upper limb
What does the left common carotid artery supply?
The left side of the head and neck
What does the left subclavian artery supply?
The left upper limb
What is coarctation of the aorta?
Narrowing of the vessel which leads to increased resistance to blood flow
What does coarctation of aorta lead to?
Blood supply to rest of body is reduced. Leads to collateral circulation between proximal and distal aorta via intercostal and internal thoracic arteries
Why is blood flow to head, neck and upper limbs not compromised in coarctation of aorta?
As the vessels supplying them emerge proximal to the coarctation
What are the heart muscles (myocardium) fed by?
Coronary arteries
Where is the aortic valve?
Between the left ventricle and the aorta
Where is the mitral valve?
Between the left atrium and the left ventricle
Where is the pulmonary valve?
Between the right ventricle and pulmonary artery
Where is the tricuspid valve?
Between the right atrium and right ventricle
The human heartbeat is often described as a ‘lub-DUB’ sound. What is the ‘lub’ and ‘dub’ produced by?
‘Lub’ –> Tricuspid and mitral valves closing
‘Dub’ –> Closing of pulmonary and aortic valves
Where does the thoracic (descending) artery span from?
Level of T4 to T12. It continues from the aortic arch.
Where does the thoracic artery leave the thorax via?
The aortic hiatus in the diaphragm where it becomes to abdominal aorta
What are the intercostal and subcostal arteries?
Small paired arteries that branch off throughout the length of the thoracic aorta
What do the intercostal/subcostal arteries supply?
Intercostal –> supply the intercostal spaces (exception of first and second which are supplied by a branch from the subclavian artery)
Subcostal –> supply the flat abdominal wall muscles
Where does the aorta terminate?
Level of L4 by abdominal aorta bifurcating into the left and right common iliac arteries
What 2 pairs of arteries supply the limbs?
Upper limb = subclavian
Lower limb = external iliac
Describe the electrical conduction during a heartbeatt
- The SA nodes (pacemaker of the heart) sends out an electrical impulse
- The upper heart chambers (atria) contract and pump blood into ventricles
- The AV node sends an impulse into the ventricles
- The lower heart chambers (ventricles) contract or pump
- The SA node sends out another signal to the atria to contract which starts the cycle over again
Where is the AV node?
A group of cells at the bottom of the right atrium
Where is the SA node?
Top of the right atrium
Why does the AV node slow the signal down?
So the atria ad ventricle don’t contract at the same time
What supplies the main conducting centres of the heart?
The right coronary artery
What can blockage of coronary arteries lead to?
Ischaemia (reduced/inadequate blood supply) which can lead to myocardial infarction (necrosis)
Where does the heart reside?
In the pericardial sac
What is the pericardium? How many layers does it have?
The membrane enclosing the heart. 3 layers:
- Outer fibrous layer
- Inner double layer of serous membrane
- One closely related to fibrous pericardium (parietal layer of serous pericardium)
- Another layer lies on surface of heart (visceral layer of serous pericardium) or epicardium
What/where is the thymus gland?
- Lies in anterior mediastinum for short period of time (in childhood)
- Important for immune response during childhood
- As we get older, gland becomes a fatty filled structure
What drains into the superior vena cava?
The right and left brachiocephalic veins
What doe the superior/inferior vena cava empty out into?
The right atrium
Why does the heart move during respiration?
Pericardium attached to central part of diaphragm
What is the connection between the pulmonary trunk and the aortic arch called? What is the purpose of it as a foetus?
Ligamentum (closed structure in adults)
In foetal development –> patent vessel (duct) that allows blood to pass from pulmonary trunk into arch of aorta (bypassing lungs)
What is base of heart formed by?
Right and left atrium
What is apex of heart formed by?
Predominantly by left ventricle
What are the 2 pericardial sinuses?
- Transverse
- Oblique
Where is the transverse pericardial sinus?
Passage between venous and arterial mesocardia
Behind the aorta and pulmonary artery and anterior to the superior vena cava
Why is the transverse pericardial sinus clinically important in bypass surgery?
- Put tube into aorta and tube into pulmonary trunk. Complete blockage and gather deoxygenated blood (that would usually go to lung). Reoxygenate that outside body (special machine). Put tube back into aorta and reoxygenate body.
Where is oblique pericardial sinus?
Lies behind left atrium and in between left and right pulmonary veins
What does left/right oracle of atrium act as?
Reserve when there is increased amount of blood flow back to the heart (during exercise)
What do all the branches of the coronary system emerge from?
Right and left coronary artery
What does left coronary artery branch into?
- Anterior interventricular artery
- Left circumflex artery
What is purpose of cusps/valves?
When heart relaxes, cusps catch any residual blood that tries to return to ventricle
What are the aortic sinuses?
Left and right aortic sinuses are dilations in the ascending aorta that are located at the level of the aortic valve
What do aortic sinuses give rise to?
Right and left coronary arteries emergy from aorta at aortic sinuses
What is the coronary sinus?
Where vast majority of coronary veins drain into (contains deoxygenated blood which then empties into right atrium
Nerves give branches that all intermingle together to form what?
A plexus of nerves:
- Pulmonary plexus
- Cardiac plexus
- Oesophageal plexus
What is a plexus?
A network of nerves or vessels
What side of the root of the lung does the vagus/phrenic nerve pass?
Vagus nerve –> passes posterior to root of lung
Phrenic nerve –> passes anterior to root of lung
Branches of which nerves go on to give branches to some of the plexuses?
Sympathetic chain and vagus nerve
Why are plexuses known as autonomic plexuses?
Have paraympathetic and sympathetic input
What supplies the plexuses with sympathetic imput?
Sympathetic chain
What supplies the plexuses with parasympathetic imput?
The vagus nerve
What is purpose of cusps in valves?
Pushed open to allow blood flow and which then close together to seal and prevent backflow
What are the aortic sinuses?
Left and right aortic sinuses are dilations in the ascending aorta that are located at the level of the aortic valve. Give rise to left and right coronary arteries that supply the myocardium.
Coronary arteries emergy from aorta at aortic sinuses
