Lecture 4: How does the cardiovascular system work? Flashcards
What are the 2 circulations of the Cardiovascular system?
Systemic and pulmonary circulations
Which organ does the pulmonary circulation supply?
Lungs
Which organs does the systemic circulation supply?
All the organs, tissues and cells of the body.
What is the mediastinum?
The midline space between the two lungs.
Describe the heart’s location in the body. (3)
- Slightly left of the midline
- Deep to the body of the sternum
- Deep to the medial ends of costal cartilages 2 and 6.
What is the pericardium?
A 3 layered bag located in the mediastinum that protects the heart.
What are the three layers of the pericardium? (Outer to inner)
- Fibrous pericardium
- Parietal serous pericardium
- Visceral serous pericardium
What are the positive functions of the fibrous pericardium? (2)
- Prevents overfilling of the heart.
- Prevents cardiac injury (For example from penetrating knife injuries.)
What is haemopericardium?
When the pericardium fills with blood.
What is cardiac tamponade?
When pressure of fluid surrounding the heart prevents it’s contraction.
What is a negative feature of the fibrous pericardium?
If haemopericardium occurs, it causes cardiac tamponade.
What are cardiac myocytes?
Spirals of cardiac tissue.
Name and describe the three layers of tissue that make up the heart.
- Epicardium (Visceral serous pericardium)
- Myocardium (Makes up most of the heart wall, made up of cardiac myocytes).
- Endocardium (internal lining, continuous with the endothelium of connecting blood vessels)
Name the three clinically important surfaces of the heart.
- Anterior (sternocostal) surface
- Base (posterior surface)
- Inferior (Diaphragmatic surface)
Describe the process that pumps blood from the heart.
Cardiac myocytes contract (Think “wringing out”) in a coordinated fashion.
What is the septum?
The internal wall of the heart that separates it into a left and right section.
Describe the function of the right side of the heart.
Pumps deoxygenated blood from the systemic circulation into the pulmonary circulation.
Describe the function of the left side of the heart.
Pumps oxygenated blood from the pulmonary circulation into the systemic circulation.
Describe the blood flow through the heart naming the vessels and structures is passes through. (Start with vena cava) (8)
- Vena cava
- Right atrium
- Right ventricle
- Pulmonary trunk and pulmonary arteries
- Lungs
- Pulmonary veins
- Left atrium
- Left ventricle
Name the valve between the Right atrium and ventricle.
Tricuspid valve
Name the valve between the right ventricle and the pulmonary trunk.
Pulmonary valve
Name the valve between the left atrium and ventricle.
Bicuspid (Mitral) valve
Name the valve between the left ventricle and the aorta.
Aortic valve
What is the function of the heart valves?
They ensure unidirectional flow of blood.
Where does conduction in the heart start, and where is this position anatomically?
At the Sinoatrial Node (SAN), located on the superior wall of the right atrium.
What is the interatrial septum?
The wall that separates the left and right atria.
Describe the route of impulses from the atria to the ventricles.
- Sinoatrial node
- Atrioventricular node
- Atrioventricular bundle
What is the function of the cardiac skeleton?
It restricts the spread of the cardiac impulses by acting as an insulator.
Describe the parts of the cardiac skeleton. (7)
- Fibrous ring of pulmonary valve.
- Fibrous ring of aortic valve
- Crux of the heart (Junction of all 4 chambers)
- Fibrous ring of tricuspid valve
- Fibrous ring of mitral valve
- Fibrous parts of interatrial septum
- Fibrous parts of interventricular septum
What is fibrillation?
An uncoordinated contraction of the cardiac myocytes that results in ineffective pumping of blood.
What is the cardiac plexus?
The mixture of nerves that supply the heart.
Describe the action of the sympathetic nerves on the heart. (2)
- Increase heart rate
- Increase force of contraction
Describe the action of the parasympathetic nerves on the heart. (1)
Decrease heart rate
