Module 5: Cardiac Physiology Flashcards
List the 5 functions of the circulatory system
- Gas exchange
- Nutrient and Water delivery and absorption
- Removal of head and metabolic waste
- Immunity and defence
- Cell communication
T/F
The circulatory system is a closed loop system
True
How is blood both serial and parallel?
System as a whole is serial
Systemic circulation is parallel
Describe series flow (in terms of electrons)
Electrons can only flow down one path in a clockwise direction
Describe parallel flow (in terms of electrons)
Electrons can flow down many paths in a counter clockwise direction, but can flow down intermediate pathways
The septum of the heart does what?
Separates the left and ride sides of the heart
The heart consists of how many pumps?
2
Each pump is divided into how many chambers? what are they called?
- An upper chamber: the atrium. And a lower chamber: the ventricle
T/F
Veins only carries deoxygenated blood
False!
It carries blood TOWARDs the heart
See the pulmonary vein for example
Describe the flow of blood throughout the body
- O2 rich blood is pumped from the left ventricle to the aorta
- O2 rich blood is delivered to the tissues and organs
- nutrients are removed from the blood while waste is added into the blood
- oxygen poor blood circulated into the veins and into the right atria via the vena cavae
- Blood is pumped into the right ventricle then through the pulmonary artery to the lungs
- CO2 is removed form blood and O2 is added back
- O2 rich blood flows through pulmonary vein into left atria where it is pumped into the left ventricle
When there is greater pressure behind a cardiac valve, what happens?
It opens
When there is greater pressure in front of a cardiac valve, what happens?
It closes
Where is the atrioventricular valve located?
Between the atria and ventricles
To prevent inversion of the valves, what are they connected to?
The papillary muscles of the ventricular walls via the chordae tendinae
The right AV valve is also called what?
The tricuspid valve
The left AV valve is also known as what?
The bicuspid valve and mitral valve
Where are the semilunar valves located?
Between the ventricles and arteries that leave them
Where is the pulmonary valve lcoated?
Between the right ventricle and the pulmonary artery
Where is the aortic valve located?
Between the left ventricle and the aorta
T/F
Semilunar valves contain chordae tendinae to prevent inversion
False
Inversion is prevented solely on their shape
Valvular heart disease (VHD) is the dysfunction of what?
The valves in the heart
VHD arises in which two forms
Either regurgitation or stenosis
What characterizes regurgitation
Occurs when a valve does not close properly
Describe regurgitation
Valves do not close properly leading blood flowing back into the compartment in which is came from. Can occur in any of the 4 valves
Regurgitation can lead to what?
Irregular heart rhythms and unnecessary stress on the walls
Can lead to heart failure
What characterizes stenosis
The narrowing of the valve due to thickening/inflammation of the valve
Describe stenosis
Can occur in any of the heart valves
Inhibits flow of the blood out of the ventricle/atria
Intercalated discs are composed of what?
Desmosomes and gap junctions
What are the function of desmosomes in intercalated discs?
To mechanically hold the cells together
What are the function of gap junctions in intercalated discs?
To allow cells to communicate and spread action potentials from cell-cell
What is the function of intercalated discs?
To allow the chambers of the heart to coordinate a contraction and efficiently push out blood
Describe the structure of the pericardial sac
A double membrane consisting of the fibrous and serous layer
What is the function of the pericardial sac?
To protect the heart from the rest of the chest cavity
What is the function of the fibrous layer?
To anchor the heart to the surrounding walls, keeping it in place during movement
To prevent it from overfilling with blood
What is the structure of the serous layer?
Divided into the parietal and visceral pericardium
What is the function of the serous layer?
To lubricate the heart with pericardiac fluid and prevent friction during activity
T/F
The heart is a mechanical organ
False!
It’s an electro-mechanical organ
u goon
What are cardiac auto-rhythmic cells?
Specialized cardiac muscle cells that can generate action potentials
Where are cardiac auto-rhythmic cells located?
In the:
sinoatrial (SA) node
atrioventricular (AV) node
Bundle of His
Purkinje fibres
Describe the location of the SA node
Located in the right atrial wall near the opening of the superior vena cava
Describe the location of the AV node
Located in the right atria where the right atria and right ventricle come together
Describe the location(s) of the Bundle of His
Cells arise from the AV node and divide into two bundle branches that travel down each side of the septum to the bottom of the heart where they curve around and travel back towards the atria
Where do purkinje fibres originate from and go to
Branch off of the Bundle of His and spread along the inner surface of the ventricles
What are the pacemaker cells?
The auto-rhythmic cells in the SA node
What would happen if there were no pace maker cells?
The heart wouldn’t beat
What do pacemaker cells do?
They control heart rate, keeping it at about 70-80 bpm
T/F
Atrial contraction accounts for 80% of total ventricular filling
False!
It passive filling accounts for that.
The other 20% is from atrial contraction
What requirements need to be met for a successful cardiac excitation?
Atrial excitation and contraction should be complete before the onset of ventricular contraction
Excitation of the cardiac muscle fibres need to be coordinated
The pair of atria and the pair of ventricles must be functionally coordinated
If the ventricles were to contract at the same time as the atria, what would occur?
Incomplete ventricular filling
Uncoordinated depolarization of the cells in the ventricles is also called what?
Ventricular fibrillation