Cardiac Physiology Flashcards
Where is the heart located?
6
Near the anterior chest wall
Directly posterior to the sternum
Slightly left of the midline
Projects inferiorly and slightly anteriorly
Projects to the left
Posterior to the sternum
How many times does the heart beat a day?
100,000 times a day
How many chambers does the heart have?
Four
How big is the heart?
Size of a clenched fist
How many litres of blood does the heart pump a day?
8,000 L a day
Name the four chambers of the heart.
Right atrium
Right ventricle
Left atrium
Left ventricle
What does the right atrium do?
Collects blood from the systemic circuit (deoxygenated blood from the body)
What does the right ventricle do?
Pumps blood to the pulmonary circuit (to lungs to be oxygenated)
What does the left atrium do?
Collects blood from the pulmonary circuit (oxygenated blood)
What does the left ventricle do?
Pumps blood to the systemic circuit
How does blood flow through the heart?
7
Systemic circuit -> right atrium -> right ventricle -> pulmonary circuit -> left atrium -> left ventricle -> systemic circuit
Where are the large/great vessels connected?
To the base of the heart/the superior aspect
What are the four main great veins?
Aorta
Vena Cava
Pulmonary veins
Pulmonary artery
What happens in right heart failure?
Can’t pump blood to the lungs
What happens in left heart failure?
Cant pump blood to the body
What happens during a single heartbeat?
2
First both the atria contract
Then both the ventria contract
During a heartbeat what happens when the ventria contract?
3
During this, both ventria eject equal volumes of blood
The right ventricle pumps its blood into the pulmonary artery
The left ventricle pumps its blood into the aorta
What is the pericardium?
5
A fibrous sac that surrounds the heart
There is a small amount of fluid between the sac and the heart
Inner layer = attached to muscle wall of the heart (visceral layer/epicardium)
Fluid
Thick fibrous membrane that attaches heart to diaphragm (parietal layer)
What cavity is the heart located in?
The mediastinum cavity
Other than the heart what else is found in the mediastinum cavity?
The oesophagus and the trachea
What is the name of the inner membrane of the pericardium?
2
Visceral layer
Epicardium
What is the name of the outer membrane of the pericardium?
Parietal layer
What are viscera?
The soft organs of the body
What type of membranes make up the pericardium?
a double serous membrane
What is the function of the pericardial fluid?
Lubricates the heart
What is the coronary sulcus?
2
Deep grove on the external surface of the heart
It marks the border between the atrial chambers and the ventricle chambers
What marks the border between the atrial chambers and the ventricle chambers?
The coronary sulcus
What are the anterior and posterior interventricular sulci?
Shallow depressions between the ventria on both the anterior and posterior positioning
What do all the sulci mark out?
They mark the route for the coronary arteries and veins (blood supply for heart)
How many layers are there to the heart wall?
Three
What are the three layers to the heart wall?
Epicardium
Myocardium
Endocardium
What is the epicardium?
The visceral pericardium, the serous membrane composed of mesothelium and loose areolar connective tissue
What makes up the epicardium?
2
Mesothelium
Loose areolar connective tissue
What makes up the endocardium?
Simple squamous endothelium supported by areolar tissue
What is the myocardium?
The muscle wall of the heart
What does the myocardium form?
The atria and ventria
What does the myocardium consist of?
3
Concentric layers of cardiac muscle
Blood vessels
Nerves
Describe the structure of the myocardium.
3
The muscle layer forms two sheaths of muscle
One sheath around the atria
Another sheath around the ventria
Describe the muscle of the heart.
6
Made of interconnected cardiac muscle cells
Secured by desmosomes
Linked by gap junctions
Convey force of contraction
Propagate action potentials
Muscle cells are connected at intercalated discs
What is the function of intercalated discs?
If one cell becomes excited the whole sheath of muscle will become excited
What is the endocardium?
It lines the inner surface of the heart and valves
What is the endocardium made of?
2
Simple squamous epithelium (continuous with endothelium of the large blood vessels)
Some areolar connective tissue
What is the epithelium of blood vessels called?
Endothelium
What is carditis?
Inflammation of any one of the heart wall layers
What allows excitation to spread through a sheath of muscle?
Myofibres
What exactly is the excitation of muscle?
Excitation is an electrical process in the form of depolarisation
How many syncytia does the heart have?
Two
What are the two syncytia of the heart?
The atrial syncytium
The ventricular syncytium
What is the conduction system of the heart?
2
The SA node passes signal to atrial muscle (through wires spread across atria) and to the AV node at the same time
The AV node passes signal to ventricle muscle
What is the SA node more often called?
The pacemaker
