Lecture 10: Cardiovascular Physiology Flashcards
What is the cardiovascular system?
The heart, arteries, veins & capillaries
What is the heart?
A muscular pumping device that pumps blood through the body
What are arteries?
Carry blood away from the heart
What are veins?
Carry blood towards the heart
What are capillaries?
Found within tissue and where nutrient transfer occurs
What is the order of blood vessels?
Artery -> arterioles -> capillary bed -> venule -> vein
Why do arteries have thicker muscle layers than veins?
To control blood pressure
What are the three types of arteries?
Elastic, muscular, and arterioles
What are elastic arteries?
They are closest to the heart and have elastic tissue to withstand large blood pressure changes
What are muscular arteries?
They deliver blood to organs and have most smooth muscle vasoconstriction
What are aterioles?
They are the smallest artery and control blood flow to capillary beds (vasoconstriction/-dilation)
What are capillaries?
They are organized into “beds” or networks. They are of the smallest diameter and where nutrient transfer occurs.
What are the three types of capillaries?
Continuous, fenestrated, and sinusoid.
What is the function of continuous capillaries?
They diffuse small chemistries (oxygen and CO2
What is the function of fenestrated capillaries?
There are pores for more diffusion (kidneys and glands)
What is the function of sinusoid capillaries?
They are very leaky and proteins & blood cells can pass through
What are veins?
They carry blood to the heat and have a much lower blood pressure which allows them to have a much thinner muscle layer & walls.
How does blood get back to the heart?
Large diameter = less resistance to flow. One way valves prevent backflow.
What is the pericardium?
The pericardium is the double membraned sac that surrounds the heart.
What are the layers of the heart?
The layers in order are: fibrous, parietal, pericardial cavity, visceral pericardium, myocardium, and endocardium.
What are the three main heart layers?
The epicardium, myocardium, and endocardium
What is the epicardium?
The inner layer of pericardium (visceral pericardium)
What is the myocardium?
It is the cardiac muscle tissue, or the bulk of the heart. It is straited and involuntary
What is the endocardium?
It is connective tissue and squamous cells. It is a line inside the heart and forms valves.
Describe the flow of blood in the body.
It enters the right atrium via vena cava and passes into the right ventricle through the tricuspid valve. It exits via pulmonary valve and enters the pulmonary artery where it goes to the lungs. It goes from the lungs to the pulmonary vein to the left atrium. From the left atrium it travels to the left ventricle via the mitral valve. From there it goes to the aorta via the aortic valve and then enters into general circulation
What are atrioventricular valves?
There are tricuspid and bicuspid (mitral) valves that separate the atria from the ventricles. Small flaps (cusps) connected to the ventricle by chordae tendineae. When the heart is relaxed/atria contracts the valves (cusps) open to allow blood flow. When ventricles contract the pressure of blood against cusps flips them shut, preventing backflow
What is the semilunar valve?
It separates ventricles from arteries. The default position is closed due to back pressure from the artery and they are then pushed open from force of the ventricles contracting.
What happens when the semilunar valve closes?
As ventricles relax & intraventricular pressure falls, blood flows back from arteries, filling the cups of semilunar valve & forcing them to close.
What happens when the semilunar valve opens?
As ventricles contract & intraventricular pressure rises, blood is pushed up against the semilunar valves, forcing them open
