Cardiovascular System - Lecture 4 Flashcards
What are the 8 great vessels of the heart?
superior vena cava
right pulmonary artery
right pulmonary veins
inferior vena cava
aorta
left pulmonary artery
left pulmonary veins
pulmonary trunk
What 3 parts of the heart do you see when you take a vertical cross-section through it?
- right ventricular wall
- left ventricular wall
- inter-ventricular septum
Where do the 2 coronary arteries branch off?
the aorta
What do the coronary arteries supply?
the heart muscle with oxygenated blood
Where do the coronary veins and coronary sinus empty deoxygenated blood?
into the right atrium
What do blockages of coronary arteries result in?
myocardial infarctions (heart attacks)
What are the 4 valves of the heart?
- tricuspid valve
- pulmonary valve
- bicuspid valve
- aortic valve
What do the fibrous rings of the heart surround?
the valves
What is the function of papillary muscles?
prevent backflow
What is the function of the chordae tendineae?
pulls the walls of the ventricles inward during contraction
What are the 4 layers of the heart wall?
- pericardium (pericardial sac)
- epicardium
- myocardium
- endocardium
What does the pericardium prevent?
overfilling
What does the pericardium provide?
pericardial fluid
What is pericardium fluid?
lubricant to allow the heart to freely contract
Where is pericardial fluid generated from?
serous membrane
What kind of cells are found in the epicardium?
epithelial cells
What is found in the myocardium layer?
muscle
What kind of cells are found in the endocardium?
endothelial cells
What is another name for the Bundle of His?
AV bundle
What structure is the main pacemaker?
the SA node
What two structures can spontaneously beat if the SA node fails to fire?
the AV node and the cells of the His-Purkinje system
What is the activation sequence of the heart?
- sinus node
- atria
- AV node
- bundle of his
- left and right bundle branches
a) septum (left to right and down) - purkinje fibres
- left and right ventricular myocardium
endo to epi
What does the bundle of his divide into?
left and right bundle branches
Which bundle branch is not completely isolated from the septum?
the left bundle branch
What is the direction of propagation in the septum?
left to right, top to bottom
Why is the right bundle branch completely isolated from the septum?
because it is well insulated
Which part of the heart initiates an impulse?
the sinus node
Where does the AV node transfer the signal from the sinus node?
from the atria to ventricle via bundle branches
What is the secondary pacemaker?
the AV node
Where do the bundle branches rapidly conduct signals to?
from AV node to Purkinje fibres
What do the bundle branches’ anatomy cause to activate first?
the septum
Where do Purkinje fibres run?
under endocardium
What cells do the Purkinje fibres activate?
the ones in both ventricles
What direction do Purkinje fibres conduct?
from edo to epi (inside out)
What kind of muscle is found in the myocardium?
striated muscle
What is found at the ends of the myocytes?
intercalated disks
How are connections between myocytes done?
via gap junctions
What can flow freely through the gap junctions?
ions
What is the resting potential of a cardiac cell?
hyperpolarized = -90 mV
Why do positive ions move between cardiac cells?
because of electrical gradient between cells
How does K+ move?
A-> B (cytoplasmic)
How does Na+ move?
B -> A (interstitial)
What happens during activation?
depolarization
What happens during relaxation?
repolarization
Where can interstitial currents be sensed?
at the surface of the body
What direction do local currents flow?
opposite direction
(T or F) All deoxygenated blood passes through either the superior or inferior vena cava on its way to the right chambers of the heart.
False. The heart’s own circulation empties directly into the right atria
(T or F) The pulmonary artery transports oxygenated blood from the heart.
False. In general, arteries carry oxygenated blood, but exception are pulmonary vessels.
(T or F) The Purkinje fibres can fire their own if an impulse isn’t generated by the sinus node.
True. All the cells of the specialized conduction system have the potential to beat on their own. They usually don’t as the SA node is faster.
(T or F) The Purkinje fibres form synapses with the myocardium in the ventricles, allowing the ventricles to fire in synchrony.
False. Purkinje fibres are muscle fibres and don’t form synapses. Only nerves do that.
(T or F) Na+ ions pass through gap junctions of cells where one is active and the other is resting.
True. Although Na+ concentrations aren’t nearly as high as K+ inside cells, they can still pass through gap junctions. Their impact on the local circuit current is mostly in the interstitial space.
Where are gap junctions concentrated in the cell?
at the end of it
What can the AV node and cells of the His-Purkinje system do if the SA node fails to fire?
spontaneously beat
