Lesson 15: Topic 11 and 12 - Cardiac Structure and Function and Cardiac Conductance Flashcards
what is the role of the cardiocirculatory system?
- key: transport things (O2 and CO2, substrates, hormones, immunological agents)
- regulates temperature
what does the circulatory system move?
blood
what does blood generally consist of?
- plasma (O2 and CO2 is dissolved in it)
- red blood cells (have hemoglobin where O2 binds)
- buffy coat (platelets and white blood cells)
what does the buffy coat of blood do?
- allow for clotting and movement of inflammatory markers
what are the three parts of the circulatory system?
- lungs
- heart
- organ systems (anything that requires O2)
which side of the heart receives deoxygenated blood?
the right side
what does the arterial system (systemic arteries) do?
takes blood away from the heart to the systemic arteries so that they can feed the various organs and systems to provide oxygen for internal cellular respiration
what does the venous system (systemic veins) do?
takes blood towards the heart after we have gas exchanges at the level of the systemic organ tissue
what does the pulmonary system (pulmonary arteries and veins) do?
- AKA pulmonary circulation
- the blood flow form the heart to the lungs and back again
when blood is represented as red, what does this mean?
- oxygenated
- hemoglobin in the blood is 100% saturated with oxygen
which arteries do not carry oxygenated blood?
the pulmonary arteries (it is flipped in the pulmonary system)
what is the artery by definition?
blood carried away from the heart
- systemic arteries carry blood from the heart and so do pulmonary arteries
what does the pulmonary vein do?
carries oxygenated blood back to the heart
what is the pressure relatively like in the arterial system?
high pressure
what is the pressure relatively like in the venous system?
low pressure
what is the pressure relatively like in the pulmonary system?
low pressure
why does the systemic arteries need to have a high pressure?
because it is leaving the heart to go to the rest of the body, so it has a lot of places to go
why does the systemic veins need to have a low pressure?
because once the blood is coming from the capillaries, it is a very low pressure to ensure smooth gas diffusion and transport. however, there is no heart to pump it from there so the pressure remains low
why is there a low pressure in the capillaries?
when the arterial blood gets to the capillaries for diffusion throughout the body, that’s a very low pressure (we do not want high pressure in the capillaries because it can decrease transit times and lead to issues with gas diffusion)
how does blood get pushed up in the venous system since the pressure is low?
- there is a set of valves in the venous circulation that helps. the blood goes up a little bit and the valves prevent backflow
- our chest, the intrathoracic pressure drops and actually sucks and pulls blood back into the heart because it is a negative pressure (acts as a vacuum)
which system has a lower pressure, venous or pulmonary?
venous
why does the pulmonary system have a low pressure?
- it has a short distance to travel and we want low pressure to allow for gas exchange
he doesn’t say this but this is what i think:
how is the pressure in the circulatory system generated?
by the heart
why is low pressure good for gas exchange?
high pressure makes the blood move too fast (placelles law)
what are we measuring when we measure blood pressure?
arterial blood pressure (venous is almost 0)
why is it important that the arterial blood has a pressure?
it is a driving pressure to allow the blood to be pushed throughout the body because if you have too low of the blood pressure, that is hypotension which can be very dangerous
what can hypotension lead to?
a lack of perfusion to critical organs such as the brain
is the lung a muscle?
no
is the heart a muscle?
yes
what are the components of the heart?
- four chambers (two atria, two ventricles)
- right side and left side
what merges into the right atrium?
the superior and inferior vena cava
when the right atrium contracts, the blood gets pushed in the right ventricle. but what does it pass?
the AV valve (right atrioventricular valve)
when the right ventricle contracts what happens?
blood is pushed up through the pulmonary semilunar valve into the pulmonary arteries and branches to all the capillaries
how does blood come back to the heart?
through the pulmonary veins as oxygenated blood
the pulmonary veins dump the blood in?
the left atrium and then goes through the left AV valve into the left ventricle to then go through the aortic semilunar valve towards the aorta and then to the body.
what is in between the ventricles?
the interventricular septum
- it is a thick mass of muscle with lots of muscle and nervous cells
what does blood flow follow?
blood moves down pressure gradients
the pressure gradients in the heart is created by?
contraction of the chambers
what happens if we do not have cardiac valves?
the system cannot properly function
- the heart can contract in perfect timing but there will be just no way to prevent backflow because it is constantly changing pressure gradients between the ventricle and the atria
- essentially: we will not have pressure gradients and won’t be able to delivery blood out of the heart to the body
what does the valves of the heart do?
prevent backflow
what does it mean to say that the valves are passively open?
- there is no muscle to open the valves, they just open passively from pressure gradients
what does the four valves seperate?
- right atrium and ventricle
- left atrium and ventricle
- left ventricle from aorta
- right ventricle from pulmonary artery
what does AV stand for?
atrioventricular
which AV valves has two cuffs and which has three?
three: right AV valve (tricuspid)
two: left AV valve (bicuspid)
“try before you buy”
why is the left AV valve a bicuspid and not a tricuspid?
left ventricle pressure are bigger than the right because it is pumping blood to the whole body
- the more cuspids = the weaker the valve (more likely to collapse or leak)
which valve is stronger?
the left AV valve to prevent backflow from the left ventricle to the left atrium
which AV valve requires a higher pressure gradient to open? why?
left AV valve because it is stronger (bicuspid instead of tricuspid)
if a bicuspid valve is stronger, why wouldn’t our right AV valve be bicuspid?
because even though its stronger, its also tougher, so it is harder to open and the right ventricular is a lower pressure system so it
what prevents the collapse of a valve?
papillary muscles
true or false: the AV valves are designed specifically for the pressures in that chamber.
true
which valve is also called the mitral valve?
left AV valve
what is connected to the papillary msucles?
chordae tendinae (small but strong tendons to help keep the structure and prevent backflow)
when someone has valvular disease, typically which valve is it regarding?
the AV valves
what is unique to cardiac muscle compared to the rest?
they have intercalated disck
what is intercalated disc?
they are a relay system, so if one has an action potential, it sends a wave of depolarization (leads to muscle shortening/contraction)
- it allows for a wave of depolarization throughout the cardiac tissue to allow for rhythmic and coordinated contraction of the cardiac muscle tissue
what nerves innervate the contraction of the heart/action potentials?
the parasympathetic AND sympathetic nerves
true or false: the heart has an intrinsic heartbeat.
true
the heart has an intrinsic heartbeat. what does this mean?
the parasympathetic and sympathetic can help control the frequency of heart contractions (heart rate)
what is our intrinsic heart beat?
100 beats per minute
what does the parasympathetic system do to our heart rate?
keeps is a bit lower than 100BPM
which nerve from the parasympathetic system controls our heart rate?
vagus nerve
what system is in more control as we have physiological stress and need a higher heart rate?
less control of parasympathetic and we start to switch to more sympathetic control
the order of cardiac contraction/myocontraction depolarization leads to?
muscle shortening contraction
what is the order of the cadiac contraction?
- atria then ventricle (if one contracts, the other is relaxing)
does the hearts chambers contract at the same time or is it a wave?
it is a wave of depolarization
- it does this so we can properly move fluid out of the heart
what are the two nodes of the heart?
- sinoatrial node (SA)
- atrioventricular node (AV)
what is the pacemaker of the heart (starts everything)?
the SA node
- generates the wave of depolarization throughout the heart and causes contraction
the AV node turns into what?
the Bundle of His
what does the Bundle of His separate into?
left and right bundle branch to go through each side of the interventricular septum
the left and right bundle branch turn into?
Purkinje fibers which connects to the cardiac muscle cell
** ** the purkinje fibers contract in what direction?
from the bottom up to allow for a nice smooth efficient ventricular contraction
where is the cardiac wave of depolarization initiated?
in the SA node
the SA node depolarization leads to?
depolarization of other cells
- spreads through via the intercalated discs
in the heart, the action potential spreads via?
the gap junction intercalated discs
while the left atria is contracting, what else is?
the right atria
- same mechanism happens between the ventricles
what is a very important purpose of the AV node?
- takes the SA node wave, dumps it down to the bottom of the heart by the bundle of his and the bundle branches but also it gives a bit of a delay of conduction through the AV node to create the rhythm.
- allows for FULL atria contraction before ventricular contraction
summary of the conducting system of the heart.
- atrial depolarization causes depolarization of atrioventricular (AV) node
- conduction through AV node is relative slow (~0.1 sec)
- allows for full atrial contraction before ventricular contraction
- travels down interventricular septum via bundle of His
- AV node and bundle of His is the ONLY electrical connection between atria and ventricles
- space between the atria and the ventricle is separated by non-conducting tissue
-Purkinje fibers rapidly distribute electrical signal to ventricles
how is the nervous system connected to the heart by?
the vagus nerve. this is to help slow and speed up as needed
