Unit 2: Cardiovascular System Flashcards
what are the 4 major roles of the cardiovascular system
to transport oxygen from the lungs to the tissues;
to transport carbon dioxide from the tissues to the lungs;
to transport nutrients from the digestive system to other areas in the body;
to transport waste products from sites of production to sites of excretion.
How many sections is the heart divided into? name them
4: right atria, left atria, right ventricle, left ventricle
What is the function of the atrias of the heart
recieve blood from organs and pump blood down to ventricles. they are the collecting chambers of the heart.
what is the overall functions of the two ventricles of the heart
pumping blood out from heart to rest of body and lungs
where does the right atria pump out blood to
lungs
where does the left atria pump out blood to
body (not lungs)
What is pulmonary circulation
right side of heart pumps deoxygenated blood into lungs
What is systemic circulation
left side of heart pumps oxygenated blood (from lungs) to rest of body
What is coronary circulation
system of vessels that supply blood to heart muscle itself
what is the muscle tissue that makes up the heart
myocardium
What is the pacemaker of the heart
the SA node
Explain the self-contraction of the SA node in the heart
inside cells there is an action potential. the inside of the action-potential is negative while the outside of the action-potential is positive. However, the heart has some leaky channels, that allow the spillage of sodium into the heart. When the inside reaches its threshold, all the gap junctions open and calcium is flooded into the hells. Calcium spreads throughout the heart, which causes a contraction.
Define syncytium
when single cell is stimulated to contract, it causes all other cardiac muscle cells to contract too
What is the heart rate monitored by
automatic nervous system
How does electricity in heart cause top-down contraction
electrical signal spreads through both atria, causing atria to contract from top down and forcing blood into ventricles. Then, the electrical signal passes from atria into ventricles. ventricles then contract
from bottom up, forcing blood into aorta and pulmonary arteries
What is an ECG and what does it do
measures electrical activity of heart
provides a graphical representation of electrical sequence of events that occur with each contraction of heart (draws each heart beat)
What is a myocardial infarction
A heart attack: when blood supply to a region of the myocardium is reduced or cut off for prolonged period of time, myocardium tissue will be damaged or die
What are the two phases of the cardiac cycle
diastole = phase of relaxation (heart is filling with blood)
systole = phase of contraction (heart contracts and ejects blood)
What propels blood to circulate within heart and body
dramatic changes in pressure
What is systolic blood pressure
pressure observed in arteries during contraction phase
What is diastolic blood pressure
pressure observed in arteries during relaxation phase
What are arteries
vessels with very thick muscular walls, which carry blood away from the heart to the different tissues and organs of the body.
what are arterioles
The arterioles are smaller than the arteries and are important in the
regulation of blood distribution to the various tissues of the body. Arterioles are surrounded by rings of smooth muscle, and these rings can contract, constricting the arteriole and reducing the amount of blood flow, or relax, opening the arteriole and increasing the amount of blood flow.
what are cappillaries
The capillaries are the smallest vessels within the body. It is in the capillaries where the main function of the cardiovascular system occurs, as well as the exchange of gases and nutrients with the tissues.
What are venules and veins
Once blood travels through the capillaries, it then enters the venules. These vessels are small, thin-walled extensions of the capillaries. The venules lead into veins, which return blood to the heart for another trip throughout the vascular system. Veins become larger as they move away from the capillaries. Many venules come together to form larger veins, until they all come together to form either the superior or inferior vena cava.
What is stroke volume (SV)
amount of blood ejected from left ventricle in single beat
what are the three things that affect stroke volume
- aortic blood pressure (as bp increase, sv decrease), 2. strength of venticular contraction (as strength increase, sv increase), 3. Amount of blood that flows into ventricle (as amount increase, sv increase)
what is the Amount of blood that flows into ventricle determined by
venous return
how does aortic blood pressure affect stroke volume
More pressure acting against the wall of the vessels will result in less blood leaving the heart and consequently a lower stroke volume
How does the strength of a ventricular contraction affect stroke volume
Stronger contraction = more blood ejected
how does the Amount of blood that flows into ventricle affect stroke volume
*Most important factor**
More blood into the ventricle will cause it to stretch, this will result in a stronger contraction, increasing stroke volume
what is venous return
how much blood gets back to the heart
what are the 4 things that can affect venous return
increases due to: 1. venoconstriction 2. action of the skeletal pump muscle 3. thoracic pump 4. nervous stimulation of the heart
how does venoconstriction affect venous return
Some veins are surrounded by a very thin layer of smooth muscle, this constricts at the onset of exercise (nervous and hormonal signals), causing blood to be ‘pushed’ back to the heart
how does action of the skeletal muscle pump affect venous return
Contraction of skeletal muscle squeezes veins, due to the one-way valves in veins, this results in blood being pushed back to the heart
how does the thoracic pump affect venous return
changes in pressure resulting from breathing cause blood found in abdominal veins to be sucked into veins of the chest/thoracic cavity
how does nervous stimulation of the heart affect venous retun
More blood pumped out = more blood returned
What is cardiac output
volume of blood pumped out of left ventricle in 1 minute (Q= SV x HR)
how can cardiac output be increased
by increasing either heart rate or stroke volume, or both
explain the blood flow of the heart
Blood enters right atrium from superior and inferior vena cavae
Blood in right atrium flows into right AV valve into right ventricle
Contraction of right ventricle forces pulmonary valves open
Blood flows from pulmonary valve into pulmonary trunk
Blood is distributed by right and left pulmonary arteries to the lungs, where it unloads CO2 and loads O2
Blood returns from lungs via pulmonary veins to left atrium
Blood in left atrium flows through left AV valve into left ventricle
Contraction of left ventricle forces aortic valve open
Blood flows through aortic valve into ascending aorta
Blood in aorta is distributed to every organ in the body, where it unloads O2 and loads CO2
Blood returns to heart via vena cavae
What are the 3 parts to a ECG reading
P-wave, RQS Complex, and T-Wave
what happens in the P-wave of an ECG
Firing of the SA node causes the atria to depolarize
Atrial contraction begins
Causes the pressure within the atria to increase
Forces blood into the ventricles (only a fraction because the ventricles are already almost full from passive blood flow down the ventricles through the open AV valves)
Atrial contraction completes
Causes pressure within the atria to fall
Causes the AV valves to close
This produces the first heart beat sound
Marks the beginning of systole
What happens in the QRS complex of the ECG reading
Ventricular depolarization (already halfway when atrial contraction is complete)
Ventricles start to contract
Rapidly build up pressure in the ventricles.
The semilunar valves remain closed, and the ventricles contract within a closed space
Referred to isovolumetric contraction as no blood is ejected and ventricular volume is unexchanged
Ventricular Ejection
When ventricular pressures exceed the pressure within the aorta and pulmonary artery
The aortic and pulmonary valves open and blood is ejected out of the ventricles
Referred to as rapid ejection phase
What happens in the T-wave of an ECG
Venticular repolarization:
Ventricular pressure starts to fall and the force of ejection is reduced
When the ventricular pressure drops below aortic and pulmonary pressure, the semilunar valves close
This marks the end of systole and the beginning of dystole
Close of these valves produce the second heart sound
The ventricles relax with the valves closed, which causes another isovulmetric contraction
The atria are being filled with blood and aortic pressure rise slowly
Venticular filling starts when ventricular pressure drops below aortic pressure which causes the AV valves to open, allowing blood to flow down into the ventricles passively
The atria contract to finish the filling phase
What is the role of the AV Node
Passes electrical signal from atria to ventricles
What passes the electrical signal from the bundle of His to the bottom of the ventricles
Purkinje fibers
What is a specialized prtein that binds oxygen and carbon dioxide
hemoglobin
what is the system of vessels that supply blood to the heart muscle itself
coronary
pressure observed in the artieries during the contraction phase of the heart
systolic
