Topic 3: Cardiovascular System Flashcards
How many times will the heart contract throughout an average human lifespan?
3 billion times
When does the heart start beating?
in the utero at three weeks
Why does the cardiovascular system develop early?
the embryo needs to be able to move nutrients and waste products early in development
What are the three components of the cardiovascular system?
- the heart
- the blood vessels
- blood
What is the function of the heart?
serves as a pump to move the blood throughout the body
What is the function of the blood vessels?
serve as passageways for the movement of blood
What are the two types of vascular loops?
- pulmonary
- systemic
What is the function of the blood?
travels throughout the body into two vascular loops
What is the function of the pulmonary vascular loop?
pulmonary circulation vessels carrying blood between the heart and the lungs
What is the function of the systemic vascular loop?
systemic circulation vessels carrying blood between the heart and the other organ systems
Where is the heart located in the body?
resides in the center of the thoracic cavity and it is surrounded by the pericardium
What are the three layers of the heart?
- epicardium (outer)
- myocardium - muscle of the heart, contracts to create heartbeats
- endocardium (inner)
What are the four chambers of the heart?
- two ventricles
- two atria
What are the functions of the two ventricles?
- muscular left ventricle pushes blood throughout the body
- the right ventricle pushes blood to the lungs
What are the functions of the two atria?
- smaller, thinner-walled chambers on top of the more muscular ventricles
- receive blood returning from the body (right atrium) or lungs (left atrium)
- hold the blood and then pump it into the ventricles
What is the movement of de-oxygenated blood?
- oxygen-poor blood enters the RIGHT atrium from the large veins known as the VENA CAVAE
- from the right atrium, blood flows through the right AV valve into the RIGHT VENTRICLE
- From the right ventricle, blood flows through the PULMONARY SEMILUNAR VALVE to the PULMONARY ARTERY to the lungs
- the right side of the heart pumps blood from the systemic circulation to the pulmonary circulation
What is the movement of oxygenated blood?
- oxygenated blood returns from the lungs and enters the LEFT atrium via the PULMONARY VEINS
- from the left atrium, the blood flows through the mitral valve into the LEFT VENTRICLE
- the left ventricle pumps the blood through the AORTIC SEMILUNAR VALVE to the AORTA and then throughout the body
- the left side of the heart pumps blood rom the pulmonary circulation to the systemic circulation
VEINS do not always carry _ blood and ARTERIES do not always carry _ as is often though
DE-OXYGENATED, OXYGEN-RICH
What is the blood flow in the circulatory system (overall)?
- in pulmonary circulation, all blood flows through the lungs
- in systemic circulation, the blood flows to various organs systems in a series of parallel paths
How do tissues receive blood?
- blood does not pass from tissue to tissue
- each tissue receives freshly oxygenated blood directly
How many directions does blood move?
blood flows in one direction only from atrium to ventricle
What prevents blood from going back in the wrong direction?
a series of VALVES located in several places; valves open in response to pressure form one direction only
When pressure is _ behind the valve, the valve _
greater, opens
When pressure is _ in front of the valve, the valve _
greater, closes
What makes the heartbeat sound?
when valves slam shut
What are the valves that control blood flow between the atria and ventricles?
the RIGHT AND LEFT ATRIOVENTRICULAR VALVES or AV VALVES
What is the TRICUSPID valve?
the right AV valve that has three leaflets
What is the BICUSPID valve?
the left AV valve that has two leaflets
What are the two leaflets at the bicuspid valve?
the left AV valve; MITRAL VALVE
Where is the SEMILUNAR VALVES?
there are two between the ventricles and the arteries into which the blood is pumped
What are the two SEMILUNAR valves?
- aortic semilunar valve
- pulmonary semilunar valve
Where is the aortic semilunar valve?
between the LEFT VENTRICLE and the AORTA
Where is the pulmonary semilunar valve?
between the RIGHT VENTRICLE and the PULMONARY ARTERY
Why are the SEMILUNAR valves SEMILUNAR?
each leaflet is cup-shaped-like a half moon
What are the normal heart sounds?
“lub-dub”
What is S1 (“lub”)?
a resonating sound caused by blood pressure against the atrioventricular valves (sound is the result of the closing of AV valves)
What is S2 (“dub”)?
a snapping sound when the ventricles relax and blood in the arteries flows back toward the ventricles (closing of semilunar valves)
What is the cardiac cycle?
the cycle of heart muscle alternately contracting and relaxing
What are the three periods of the cardiac cycle?
- diastole (relaxation period)
- atrial systole
- ventricular systole
What happens in diastole?
at the beginning of the cycle, the heart is completely relaxed, with blood entering both the left and right atria
What happens in atrial systole?
as the heartbeat begins, the atria contract. This forces the blood from the atria into the ventricles
What happens in ventricular systole?
the atria relax during ventricular systole. The ventricles remain contracted for a measurable time, and then the entire heart returns to diastole
In atrial systole, the AV valves are _, semilunar valves are _
open, closed
In ventricular systole, the AV valves are _, semilunar valves are _
closed, open
What causes blood pressure?
- blood volume does not change during the cardiac cycle
- force generated by the left ventricle results in a change in blood pressure from the relaxed state
What is the expression for blood pressure?
systolic pressure/diastolic pressure (ex. 120/80mmHg)
What is systolic pressure?
the force with which left ventricle pushes blood through the circulatory system