Cardiovascular Physiology Flashcards
What determines blood flow in the vascular system?
A net change in pressure.
What is hydrostatic pressure
The pressure exerted by a fluid
What is viscosity?
Friction between molecules of a flowing fluid
How do the length and diameter of a vessel affect viscosity??
Increase in viscosity due to increased interaction between blood cells and the stationary vessel wall.
What is hematocrit? How does it affect blood flow?
The number of blood cells in the vessel; increases viscosity and decreases blood flow.
What is Poiseuille’s equation?
R= 8nL/pi r^4
When can Poiseuille’s equation be used?
In laminar blood flow only.
What are the four functions of the cardiovascular system?
- Delivering nutrients and removal of waste.
- Chemical signalling delivery (hormones and NT)
- Thermoregulation.
- Mediation of inflammatory and immunity response.
What are the three components of the cardiovascular system?
The heart (pump), the vessels (pipes), and the blood (fluid).
What are the components of the vessels?
Arterioles, capillaries, arteries, and veins
Arterioles
Small branching vessels with high resistance, extend off arteries.
What are capillaries?
The smallest vessel unit that extends off arterioles, facilitates diffusion in nutrients from the blood to tissue and waste from tissue to blood.
Arteries
Vessels that push blood away from the heart
Veins
Vessels that bring blood to the heart.
What are the four chambers of the heart
Right atrium, right ventricle, left atrium, left ventricle
Which chambers contain the lowest pressure?
Atria, because they receive blood returning to the heart from the body or lungs.
What is the function of the septa? What are its divisions?
The function: separate oxygenated blood from deoxygenated blood.
Divisions: Interatrial septum
Interventricular septum.
What are the two serial circuits of the cardiovascular system?
Pulmonary circulation, system circulation
Describe pulmonary circulation:
Blood enters lungs from a pulmonary branch of the right ventricle, thin tissue allows oxygen to diffuse back into blood. Enters the heart through the left atrium through the pulmonary veins.
Describe systematic circulation:
Oxygenated blood leaves the heart through the aorta and travels through arteries to various tissue and organs. Oxygen diffuses through capillaries and blood takes up waste from tissue cells. Deoxygenated blood then circulates back to the heart through veins, where it enters the right atrium through the superior or inferior vena cava.
When does series flow occur in systematic circulation?
The liver; blood is supplied by the gastrointestinal tract.
What is the function of the pericardium?
Stabilization of the heart, protection of the heart, lubrication of the heart, and limitation of the heart filling (disaster prevention).
Pericardium
The fibrous sac surrounding the heart and roots of the great vessels consists of three layers.
What are the three layers of pericardium?
Fibrous pericardium, Parietal layer, Visceral layer.
Where is the pericardial fluid found?
In the pericardial cavity
Which layers make up the serous pericardium?
Parietal and visceral layers.
Which pericardial layer is a part of the heart wall?
Visceral layer (epicardium when attached to the wall)
Why is the left ventricle larger than the right?
Must pump blood to the entire body, has to create a large pressure.
What are the layers of the heart wall?
The endocardium, myocardium, and epicardium.
What is the epicardium?
Also the visceral layer of the pericardium covers the outer surface of the heart and secreted pericardial fluid.
What is the Myocardium?
The muscular wall of the heart containing the myocytes, nerves, and blood vessels.
What is the endocardium?
The innermost layer of the heart wall. Smoothest layer to decrease resistance; covers all inner surfaces of the ventricles and atria.
Myocyte
Cardiac muscle cell
Describe the appearance and connectivity of cardiac muscle cells:
Y-branched, connect to many different myocytes. Striated in appearance, contain only one nucleus. Contain intercalated disks.
Intercalated disk
Junctions between myocytes; desmosomes or gap junctions
Desmosomes
Mechanical connections between myocytes
Gap junctions
Electrical synapses between myocytes
Valves
Thin flaps of flexible endothelium-covered fibrous tissue attached at valve rings. Made up of collagen.
What are the four valves of the heart?
Pulmonary valve
Aortic valve
Tricuspid valve
Bicuspid valve
What are valve rings
A part of the cardiac skeleton; act as structural support to anchor valves to the myocardium.
Describe the unidirectional flow of blood through the heart
Valves open and close passively due to pressure changes and not by ATP or muscular contraction. When pressure is greater behind valve, it opens. When pressure is greater in front of valve, it closes.
What are the AV valves?
Atrioventricular valves: connect atria and ventricles and prevent backflow of blood. Contain the right AV valve (tricuspid) and the left AV valve (bicuspid).
What is the valve apparatus composed of?
Chordae tendinae, papillary muscles?
What are chordinae tendinae?
Tendinous-type tissue that extend from the edges of each leaflet to the papillary muscles.
What are the papillary muscles?
Cone-shaped muscles that contract to stabilize the closed conformation of valves and prevent backflow due to increased ventricular pressure. Only present at AV valves.
What are the arterial/semi-lunar valves?
Contain three cusps and situate between the ventricles and arteries. Contain the pulmonary valve (right) and the aortic valve (left). Do not contain valve apparatus.
What is the cardiac skeleton? What is its purpose?
The fibrous skeleton of the heart that consists of dense connective tissue and valve rings. Separates atria from ventricles, contributes to support of heart, prevents electrical conductance from atria to ventricles.