Cardiovascular physiology Lecture 1 Flashcards
What is hemodynamics?
The study of blood flow
Relates Ohm’s law to fluid flow, looking at the relationship between blood flow, blood pressure and resistance
What is resistance to blood flow?
The friction that impedes flow, or how difficult it is for blood to move between 2 points at any given pressure
What formula describes flow?
Flow = change in pressure divided by resistance
Blood flow is related to the _______ between two fixed points and is inversely proportional to the _____
Blood flow is related to the pressure difference between two fixed points and is inversely proportional to the resistance
Blood always flows from a region of high ____ to a region of low ______
Blood always flows from a region of high pressure to a region of low pressure
For blood to flow, the change in pressure must be larger than _____
Resistance
What is the major mechanism for changing blood flow?
To alter the resistance of blood vessels in particular arterioles
What is hydrostatic pressure?
Blood hydrostatic pressure is the pressure that the volume of blood within our circulatory system exerts on the walls of the blood vessels that contain it
Often called “pressure”
If there is no pressure difference, what is the rate of flow?
0 ml/min
What are three factors that determine resistance to blood flow?
- viscosity of the blood
- length of the blood vessel
- diameter of the blood vessel
What is viscosity? And what effects viscosity of blood?
- The friction between molecules of a flowing fluid
- Hematocrit (#of RBC in blood) affects viscosity
What is poiseuilles’s equation for R?
R= 8nL/πr4
Resistance to flow is directly proportional to the ___\_of the ____\_ and the ______\_ and inversely proportional to the _____ of the vessel
Resistance to flow is directly proportional to the length of the vessel and the blood viscosity and inversely proportional to the radius of the vessel
R=8nL / pir4
What factor has the greatest effect on resistance?
Vessel Diameter (changed via constriction/relaxation of vascular smooth muscle)
very small changes in vessel diameter lead to large changes in resistance
What is the effect of a closed circulatory system on pressure?
Closed circulatory system allows for greater pressures to be generated when the heart contracts
small branching vessels with high resistance
arterioles
transport of blood between small arteries and veins; exchange of materials between blood and cells in the body
capillaries
carry blood away from the heart
arteries
carry blood toward the heart
veins
- Thin walled chambers
- low-pressure chambers
- receive blood returning back to the heart
atria
- thick walled chambers
- responsible for the forward propulsion of blood when they contract
ventricles
Lowest superficial surface of the heart
Apex
what separates left and right atria
Interatrial septum
What separates left and right ventricles?
Interventricular septum
Upper surface of the heart where the blood vessels attach:
Base
What feature of the heart allows it to function as a dual pump?
Separation of the left and right sides (via interatrial and intraventricular septa)
The fibrous sac surrounding the heart and roots of great vessels:
Pericardium
What are four functions of the pericardium?
- Stabilization of the heart in thoracic cavity
- protection of the heart from mechanical trauma, infection
- secretes pericardial fluid to reduce friction
- limits overfilling of the chambers, prevents sudden distension (resist large change in size)
What are the three layers of the pericardium?
- Fibrous pericardium
- Parietal pericardium
- Visceral pericardium (epicardium)
What is the serous pericardium?
Collective name for the parietal and visceral pericardium
What is the pericardial cavity?
space between the parietal pericardium and the visceral pericardium both of which secrete serous fluid to decrease friction between the meembranes
WHat is the serous layer?
a layer composed of cells that secrete a fluid
Inflammation of pericardium
Pericarditis
What does pericarditis lead to?
Inflammtion of pericardium caused by viruses, bacteria, fungi, trauma or malignancy which leads to fluid accumulation in the pericardial cavity
What is Cardiac tamponade?
Compression of heart chambers due to excessive accumulation of pericardial fluid = limits heart movement and chambers cannot fill with adequate amount of blood (ie decreases ventricular filling)
What are the three layers of the heart wall?
- epicardium (visceral pericardium)
- myocardium
- endocardium
Layer immediately outside the heart muscle is the _______ which is connected to the myocardium via ______ and functions as a:
Layer immediately outside the heart muscle is the epicardium (visceral pericardium) which is connected to the myocardium via connective tissue and functions as a: Protective layer
The muscular wall of the heart that lies beneath the epicardium is the:
What does it contain (2)
Myocardium
- Contains:
- muscle cells (myocytes) which contract and relax as heart beats
- nerves and blood vessels
What is the endocardium?
Innermost layer of the heart wall
- lines heart cavities and the heart valves;
- thin layer of endothelium which is continuous with the endothelium of the attached blood vessels
The ventricles have thicker _______ than the atria, with the left having thicker than the right
The ventricles have thicker myocardium than the atria, with the left having thicker than the right
Cardiac muscle cell
myocyte
interdigitated region of attachment - holds adjacent cells together
Intercalated disc
Two types of specialized intercellular junctions at intercalated disks
- Desmosomes
- gap junctions
What is a desmosome?
- Adhering junction that hold cells together in tissues subject tot considerable mechanical stress or stretching
- mechanically couple one heart cell to another
- involves proteins:
- cadherins
- plaques
- intermediate filaments
What is a gap junction?
- communicating junction
- electrically couple heart cells, allowing ions to move between cells
- important for spread of AP
- Proteins:
- connexons
When the cardiac muscle contract and shorten it comes together link a squeezing fist (wringing) efficiently pushing blood up. Why?
The myocardium consists of interlacing bundles of cardiac muscle fibres arranged spirally around the circumference of the heart
