Topic 4 - The Cardiovascular System Flashcards
What is the cardiovascular system responsible for?
The bulk transport of oxygen and nutrients to the tissues and waste products, including carbon dioxide away from the tissues
It also serves a vital role in the endocrine and immune systems, transporting hormones to their target tissues and conveying the cells and molecules needed to fight infection
What is the mediastinum?
The central compartment of the thoracic cavity, situated between the lungs
What does the mediastinum contain?
All the thoracic structures except the lungs and is a highly mobile region in the living because it consists primarily of hollow visceral structures which are joined by loose connective tissues
Where does the mediastinum lie?
The mediastinum extends from the superior thoracic aperture to the diaphragm and from the sternum and costal cartilages to the bodies of the thoracic vertebrae
Where does the superior mediastinum lie?
This extends inferiorly from the superior thoracic aperture to the horizontal place, which includes the sternal angle and passes approximately through the junction of T4 and T5 vertebrae posteriorly
What does the superior mediastinum contain?
The roots of the great vessels, the oesophagus and the trachea
What is the sternal angle?
The joint between the manubrium (top part) and the body (middle part) of the sternum, it is a landmark which identifies the division between the superior and inferior mediastinum
What is the inferior mediastinum subdivided into?
The inferior mediastinum is subdivided into the anterior, middle and posterior parts
Which part of the mediastinum has the heart?
Middle mediastinum
Where does the inferior mediastinum lie?
The inferior mediastinum extends inferiorly from the sternal angle to the diaphragm
Where does the phrenic nerve lie?
The phrenic nerve lies in front of the root of the lung
Where does the vagus nerve lie?
The vergus nerve lies behind the root of the lung
Where does the pulmonary artery lie?
The pulmonary artery lies above the pulmonary veins
What does the heart lie within?
The heart lies within a fibrous pericardial sac
Where is the pericardial sac blended?
The pericardial sac is blended inferiorly with the central tendon of the diaphragm
What is the outer layer of the pericardium like and what does it do?
The pericardial sac has a touch fibrous outer layer (the fibrous pericardium) which protects the heart against sudden over filling by physically preventing over expansion
What is the outer layer of the pericardium called?
The fibrous pericardium
What is the internal surface of the pericardium lined with?
Serous membrane (parietal layer of serous pericardium) which passes onto the surface of the heart (visceral layer of serous pericardium) to provide a continuous membrane surrounding the fluid filled pericardial cavity
What is the epicardium?
The epicardium is the name given to the external layer of the heart but it is actually just the visceral layer of the serous pericardium
What does the pericardium consist of?
The pericardium consists of three layers: fibrous pericardium, parietal pericardium, visceral pericardium
Describe the layers of the pericardium:
The pericardium consists of three layers:
The most superficial is the fibrous pericardium, this strong layer prevents overexpansion of the heart and protects the heart from damage
The two deeper layers are continuous with each other at the root of the great vessels
The more superficial of the two is the parietal pericardium which lines the inner surface of the fibrous pericardial sac
The deeper layer is the visceral pericardium which forms a covering for the heart, also known as the epicardium
The parietal and visceral pericardium enclose the pericardial cavity which contains pericardial fluid
This reduces friction between the two moving surfaces
What does the fluid in the pericardial cavity do?
It allows the heart to beat in an almost frictionless environment, similar to the pleura around the lungs
What is the heart?
The heart is a self-adjusting double pump that propels blood around two circulatory systems in series
What are the two circulatory systems?
The pulmonary and systemic systems
What is the heart made up of?
The heart consists of 4 chambers, 2 atria and 2 ventricles and is formed from specialised cardiac muscle known as myocardium
What is heart muscle called?
Cardiac muscle, myocardium
What does each cycle consist of?
Each cycle consists of contraction and relaxation
What is each cycle of contraction and relaxation known as?
A heart beat
What is contraction of the ventricles known as?
Systole
What is relaxation of the ventricles called?
Diastole
Is pulmonary circulation low or high pressure?
Low pressure, not much force is required to send blood the short distance through the lungs from the right to the left of the heart
What would happen if there was high pressure in pulmonary capillaries?
High pressure in pulmonary capillaries would force fluid out of the blood into the lung tissue and we would drown
Describe the route of blood to the lungs and its relative oxygen concentration:
Blood pumped to the lungs from the right ventricle has very low oxygen concentration, blood leaves the right ventricle through the pulmonary trunk which divides to give right and left pulmonary arteries, oxygenation of this blood occurs in the lungs before it returns to the heart through a series of pulmonary veins which enter the left atrium
What does pulmonary refer to?
The lungs
What does systemic refer to?
Affecting the whole body