Anatomy and pattern recognition of the cardiovascular system – part 1 – Normal appearances and variants Flashcards
What are the functions of the cardiovascular system?
Deliver nutrients and oxygen to tissues
Remove waste products of cellular metabolism (e.g. CO2)
Transport hormones and drugs
Acid base balance
Blood clotting (haemostasis)
Distribution of heat- maintain temperatures
Immune response
Aorta
Oxygenated blood from the heart is distributed from the aorta to all parts of the body
It is divided into the ascending aorta, aortic arch and descending aorta
It has a large diameter, is relatively thin walled and highly elastic
We also divide it medically into the thoracic and abdominal aorta – at the level of the diaphragm.
It has a large diameter, is relatively thin walled and highly elastic
It stretches to receive ejected blood from the left ventricle
Thoracic aorta
Is the main blood vessel in the thoracic cavity
Originates from the left ventricle
Transmits oxygenated blood to organs within the thoracic cavity, head, neck and upper limbs.
Comprises of the:
Ascending aorta
Arch of the aorta
Descending aorta
What is the Ascending aorta?
Approximately 5cm in length
Begins at the aortic valve and ends at the level of the sternal angle where it becomes the aortic arch
Contains 3 aortic sinuses, 2 of which become the right and left coronary arteries.
Right coronary artery
Supplies both ventricles and right atrium
Left coronary artery
Supplies both ventricles and the left atrium
6cm behind sternum
What is the Coronary arteries?
The coronary arteries encircle the heart
There is a left and right coronary artery which supply oxygenated blood to the myocardium
The myocardium receives blood from branches of more than 1 artery and when 2 or more arteries supply the same region they usually connect. These connection are called anastomoses.
The provide alternative routes called collateral circulation for blood to reach an organ.
The coronary arteries have many anastomoses to provide detours for arterial blood if a main route becomes obstructed. This is important – the myocardium will still receive sufficient oxygen even if 1 of the coronary arteries is blocked.
What is the Aortic arch?
4-5cm long and is the continuation of the ascending aorta
Three major branches
The brachiocephalic trunk – subdivides to form the right subclavian and right common carotid arteries
Left common carotid
Left subclavian
Thoracic / descending aorta
Approximately 20cm long, continuation of the aortic arch
Sits in posterior mediastinum cavity
Branches are:
Bronchial – bronchial tree and alveolar ducts
Posterior intercostal – skin, muscle and ribs of thoracic wall. Thoracic vertebra and spinal cord
Subcostal – skin muscles and ribs, T12
Mediastinal – mainly lymph nodes and connective tissue in the mediastinum
Oesophageal – oesophagus
Pericardial – pericardial sac
Superior phrenic artery – diaphragm and pleura
What is the Abdominal aorta?
Main vessel in the abdominal cavity
Transmits oxygenated blood from the thoracic cavity to organs within the abdomen and lower limbs
It is a continuation of the thoracic aorta
Descends in the retroperitoneum anteriorly and slightly to the left of the lumbar vertebral bodies
The inferior vena cava lies to its right
It terminates at L4 into the right and left common iliac arteries and the median sacral artery
What are Arteries?
Carry blood away from the heart to other organs
There are 2 main types
Muscular arteries
The tunica media contains more muscle and fewer elastic fibres
These arteries can vasodilate and constrict to adjust the rate of blood flow and deliver blood to the organs
Elastic arteries
The largest in the body with a thick tunica media
Includes the aorta, pulmonary trunk and aorta.
They propel blood onward while the ventricles are relaxing
What are Arterioles?
Means ‘small arteries’
They regulate the flow of blood into the capillary networks of the body’s tissues
A change in arteriole diameter can affect the blood pressure
Vasoconstriction – increases blood pressure
Vasodilation – decreases blood pressure
Veins
carry deoxygenated blood
Veins have thin wall compared to the arterial wall
Walls are formed from the same 3 layers as arteries, but the thickness of the layers is different.
Veins can distend enough to cope with variations in blood flow but cannot withstand high pressure
Veins have valves with valve cusps which point towards the heart. This prevents backflow of blood
Surface landmarks
Heart
Superior border
2nd left costal cartilage and 3rd right costal cartilage
Right border
3rd right costal cartilage and 6th right costal cartilage
Inferior border
6th right costal cartilage andthe 5th left intercostal space in the midline
Left border
2nd left costal cartilage and the 5th left intercostal space in the midline
