Introduction to Cardiovascular Anatomy Flashcards
What is the basic function of the cardiovascular system?
To maintain a constant internal environment through homeostasis
It delivers oxygen and nutrients to cells and removes CO2 and waste
Why are high pressures needed in the arterial system?
To be able to pump blood to the extremities
Where does gas exchange occur in the cardiovascular system?
At the capillary bed in the organ
Why does the venous system require valves?
They prevent the backflow of blood as venous blood is acting against gravity
Why is the heart referred to as a ‘dual-action’ pump?
It has 2 circulations:
Pulmonary circulation concerns blood going to and from the heart
Systemic circulation concerns blood going to the rest of the body
What are the 2 pumps in the ‘dual-action’ pump system?
Pump 1 is the RA and RV
Pump 2 is the LA and LV
What are the 2 functional parts of the cardiovascular system?
- conducting system
2. exchange system
What is the conducting system of the cardiovascular system?
The vasculature (tubes)
Arteries carry blood away from the heart and veins carry blood towards the ehart
What is the exchange system of the cardiovascular system?
The capillary beds which have thin walls where exchange of gases and nutrients can occur
How is a continuous exchange system between the blood and extracellular fluid formed?
The capillary beds link the smallest arterioles with the smallest venules
How does the structure of the heart allow for efficiency?
Why?
Right side of heart deals with deoxygenated blood and left side deals with oxygenated blood
If the blood was mixed, some structures would not receive as much oxygen
How are the atria specialised to their function?
What is this function?
The atria receive blood
They are specialised to this function as they can distend
How does the right atrium receive blood?
What then happens to this blood?
It receives deoxygenated blood from the superior and inferior vena cavae
This blood passes through the atrioventricular valve into the right ventricle
What happens to the blood after it has entered the right ventricle?
The ventricle ejects blood towards the lungs via the pulmonary trunk
The pulmonary trunk then splits into the right and left pulmonary arteries
After reoxygenation at the lungs, how does the blood return to the heart?
It returns to the left atrium via pulmonary veins
It then passes through the atrioventricular valve into the left ventricle
What is systole?
Systole occurs when the muscles in the heart contract
Atrial systole occurs when the atria contract and ventricular systole occurs when the ventricles contract
What is diastole?
The period when the heart chambers are relaxed and receiving blood
What is the role of the interatrial septum?
It separates the right and left atria to prevent the mixing of blood
What are pectinate muscles and what is their role?
They are muscular elevations in the wall of the atria
They prevent the atria from over-distending
What is the function of the atrial auricle?
It acts as a reserve for when there is increased blood flow
It allows the atrium to receive a bit of extra blood
What is the crista terminalis?
It is an elevation which separates the smooth and the rougher part of the right atrium
What is the fossa ovalis?
It is an indentation on the right atrial wall
it had an importance in foetal circulation
What is the role of the coronary sinus in the right atrium?
Venous blood draining from the coronary supply to the heart enters the right atrium via the coronary sinus
What causes the atrioventricular valve to open?
what is a common misconception?
Tendinous cords DO NOT pull the valve open
The force of the atria contracting pushes blood through the valve
What is the role of the tendinous cords?
They hold the leaflets of the AV valves taut during ventricular systole
This prevents them flapping back into the atria
this prevents blood from re-entering the atria
What is the role of the papillary muscle?
It is connected to the chordae tendinae and controls them
What are trabeculae carnae?
Muscular elevations in the wall of the ventricle
What happens to the right semilunar valve during ventricular systole?
As blood is ejected into the pulmonary trunk, the semilunar valve is flattened against the wall of the trunk
What is the role of the right semilunar valve during diastole?
There may be some residual blood in the pulmonary trunk
If it begins to trickle back towards the ventricle, the semilunar valves catch it and prevent it re-entering the heart
What is the difference in the atrioventricular valves on the right and left sides?
The right valve is called the tricuspid valve as it has 3 cusps
The left valve is called the bicuspid valve as it has 2 cusps
what are the 3 components of the aorta?
- ascending aorta
- aortic arch
- descending aorta
What are the branches of the aortic arch in order?
- Brachiocephalic trunk
This divides into:
i. right subclavian artery
ii. right common carotid artery
- left common carotid artery
- left subclavian artery
Which structures are supplied by the subclavian and carotid arteries?
Subclavian - upper limb
Carotid - head and neck
What are the two components of the descending aorta?
The thoracic aorta and the abdominal aorta
What are the only branches from the ascending aorta?
The right and left coronary arteries
What does the right coronary artery supply?
The main conducting centres of the heart - the SAN and AVN
What are the 2 branches of the right coronary artery?
- right marginal artery
2. posterior interventricular artery
What are the 3 branches of the left coronary artery?
- circumflex artery
- left marginal artery
- anterior interventricular artery
Why are coronary arteries described as ‘functional-end’ arteries?
They supply a specific area of the heart which other vessels do not
There is little overlap between the territories of distribution of the coronary arteries
What does a sudden blockage in the coronary arteries lead to?
ischaemia due to the reduced/inadequate blood supply to the heart
this leads to myocardial infarction which results in necrosis
Where does venous drainage from the coronary veins lead to?
The coronary veins merge into the coronary sinus, which opens into the right atrium
What is the role of the aortic valves?
They prevent blood from re-entering the left ventricle
What are the 3 vascular planes of the descending aorta?
- ventral unpaired arteries to the GI tract
- paired arteries to paired internal organs (kidneys, gonads)
- paired segmental arteries to the body wall
(e. g. intercostal arteries)
At which vertebral level does the descending aorta pierce the diaphragm?
What else must pierce the diaphragm?
vertebral level T12
The inferior vena cava must pierce the diaphragm as it has drainage of the lower half of the body
At what level does the abdominal aorta divide?
vertebral level L4
What is coarctation of the aorta?
What does it result in?
abnormal narrowing of the aorta, known as stenosis
this decreases blood flow to the inferior body
What type of circulation develops as a result of coarctation of the aorta?
Where does this develop?
Collateral circulation develops between the proximal and distal aorta via intercostal and internal thoracic arteries
What is the route that blood takes via the collateral circulation?
From the subclavian artery, the internal thoracic artery gives rise to anterior intercostal arteries
The anterior intercostal arteries join the posterior intercostal arteries which go back to the aorta to bypass the blockage
Out of the 2 pairs of arteries that supply the limbs, which arteries supply the upper and lower limb?
The upper limb is supplied by the subclavian artery
The lower limb is supplied by the external iliac artery
How do the arteries supplying the limb divide and where do they lie within the limb?
A single vessel goes to the proximal part of the limb
At the elbow and the knee, the artery divides into 2 main branches
They lie in the flexor compartment as they are protected there
Into which veins do the upper and lower limb drain?
The upper limb drains into the subclavian veins
The lower limb drains into the external iliac veins
What type of veins are used in a coronary bypass?
What is this?
Superficial veins
This is used to bypass a coronary blockage and maintain arterial supply
What type of patterns do deep veins follow?
They are usually duplicated or triplicated
There are often several accompanying veins surrounding a single artery
Which type of veins surround the radial artery?
deep veins will surround the corresponding artery
So the radial artery is surrounded by radial veins
What is the arteriovenous pump?
This uses arterial contraction and valves to aid venous return
How do the accompanying veins have a role in countercurrent heat exchange?
They help to maintain core body temperature
What are the tributaries of the superior vena cava?
The right subclavian vein and right internal jugular vein join to form the right brachiocephalic vein
The left subclavian vein and left internal jugular vein join to form the left brachiocephalic vein
Where do the right and left internal jugular and subclavian veins come from?
Subclavian vein comes from the upper limb
Internal jugular vein comes from the head
What is the passage of the lymphatic system which leads to the venous system?
- lymphatic plexuses amongst capillaries
- lymphatic vessels alongside arteries
- lymph nodes
- thoracic duct or right lymphatic duct
- venous system
what does the lymphatic system consist of?
Thin-walled tubes that transport interstitial fluid, bacteria, cellular debris and lymphocytes
Why is the lymphatic system important clinically?
It is involved in the spread of carcinomas
Patterns of lymph flow are important to predict or track back to the primary tumour
Where does the lymphatic system empty into?
How is it related to the cardiovascular system?
It is emptied into the venous system after it has collected immune cells and pathogens
The cardiovascular system and the lymphatic system together make up the circulatory system
