Mace Cardiovascular System Lecture 5a (Exam 3) Flashcards
What is the function of the cardiovascular system?
To move blood –> organ perfusion
To remove waste
What are the parts of the cardiovascular system and what are their functions?
- Heart = pumping station
- Blood vessels - Pathway - NO notable gas exchange in arteries or veins
Pulmonary capillaries exchange with air sacs
Systemic capillaries exchange with cells
Veins = carry blood back to the heart
Arteries = carries blood AWAY from the heart
T/F: Arteries and veins are mainly involved with gas exchange
False! They play a very small roll in gas exchange (5%)
ONLY capillaries allow for full gas exchange
T/F: The left side of the heart pumps more blood than the right
False!
The right and left must pump the SAME volume with each beat
If they don’t - will cause edema or pulmonary edema due to blood being left over
T/F: The left side of the heart has more/produces more pressure than the right
True!
What is the basic pattern of blood flow?
- R side of heart
- Lungs
(low pressure - lungs are close by - do not need a lot of pressure) - L side of heart
(thicker muscle and higher pressure pump) - Systemic cells
What are the functions of the two pump systems of the heart?
Each pump has a receiving chamber (atria) and a pumping chamber (ventricle)
R side: pumps deoxygenated blood to lungs
L side: pumps oxygenated blood to body
What are the Great vessels?
Arteries (arterial trunks) Pulmonary trunk Aorta Vena cavae (SVC and IVC) Pulmonary veins
What is the function of the arteries (arterial trunks)?
transport blood AWAY from the heart
What is the function of the pulmonary trunk?
Transports deoxygenated blood from the right side of the heart to the lungs
What is the function of the aorta?
Transports oxygenated blood from the L side of the heart
What is the function of the Vena cavae (SVC and IVC)?
Drain deoxygenated blood into the R side of the heart (RA)
What is the function of the pulmonary veins?
Drain oxygenated blood into the L side of the heart (LA)
What is the function of the R and L auricles?
They accept a large volume of blood rushing back to the heart.
Accept this blood until the cardiovascular system can adjust - ensure that this happens and no tearing/damage occurs to the arteries
What is the coronary sinus and what are the main takeaways that Mace wants us to know?
- Where blood goes out from ventricles
- Stops right before the RA - goes into a sinus called the Coronary Sulcus (between Atria and Ventricle)
- Drains heart of venous blood from the coronary veins
- In PULSATILE fashion blood is removed from that vessel ea. time the heart pumps
- When heart pumps - it squeezes ventricles - moving blood into the coronary sinus
- As heart relaxes - coronary sinus drops the blood into the atria
Describe the arteries of the Coronary Circulation
- The R coronary artery goes all the way around the coronary sulcus - to feed R side of the heart
- L coronary artery is very short - goes posterior to the pulmonary trunk and branches into:
- Circumflex artery (feeds the L side of heart)
- Anterior ventricular artery (LAD - goes down to the L ventricle)
Describe the Stop and Go contraction of the Coronary Arteries
- During contraction of the ventricles the vessels are compressed
- Ventricles relax - coronary arteries draw blood into the muscle itself
- Contraction = pushing blood up beyond the aortic valve into aorta towards the body
- Ventricles relax - blood sucked back towards heart
- Aortic valve closes - preventing backflow
- Closing of valve creates pressure at base of ascending aorta - pressure fills coronary arteries
To summarize, what is the function of the coronary sinus?
Drains the cardiac veins into the RA in a pulsatile fashion
How are arteries and veins packaged together?
packaged together in the same area
Ex: great cardiac vein & LAD go down the same coronary sulcus in all areas
The obstruction of the \_\_\_ will cause more severe myocardial infarction (MI) than the obstruction of any of the others? A. Left marginal vein B. Left coronary artery (LCA) C. Posterior interventricular vein D. Anterior interventricular branch E. Circumflex branch
B. Left coronary artery (LCA)
Would block everything downstream!
What is the flow of deoxygenated blood through the heart?
This should be seared into your brain by now!
- Deox blood to R atria (from SVC and IVC)
- Tricuspid valve
- R ventricle
- Pulmonary valve
- Pulmonary trunk –> artery
- Lungs
What is the flow of oxygenated blood through the heart?
- Blood comes back from the lungs via L and R pulmonary veins
- L atria
- Mitral valve
- L ventricle
- Aortic valve
- Ascending Aorta –> aortic arch
- Coronary Arteries –> Right Brachiocephalic trunk, L Common Carotid, L Subclavian
- Body (systemic system)
What is the fibrous skeleton of the heart?
Dense, irregular connective tissue
What are the functions of the fibrous skeleton?
- Provides SUPPORT for the atria and ventricle boundary (allows them to contract in a stable manner)
- Forms rings as valve anchors
- Rigid framework for cardiac muscle (muscles attach in spiral bundles)
- Electrical insulators (barrier between atria and ventricles)
What are the chordae tendinae? What is the function?
Attach to the thin AV valves in the ventricles
Secured by papillary muscles
Prevent opening of AV valves under pressure (during ventricular contraction)
Why do the papillary muscles contract just slightly before the rest of the ventricles?
They help to take the slack out of the cordae tendinae.
When ventricles contract - they pull on chordae tendinae and prevent prolapsing of the AV valves
Describe the structure of the semilunar valves
More structure compared to the AV valves
Responsive to pressure coming down from the great vessels
Responsive to pressure created when the ventricles contract (open) and when they relax (closed)
After entering the R atrium, the furthest a red blood cell will travel is the A. R ventricle B. Pulmonary trunk C. Superior vena cava D. Ascending aorta E. L atrium
C. Superior vena cava
What type of muscle makes up the heart?
Striated muscle
Describe the striated muscle of the heart
Short, branched cells
Stimulate one another in a wave
Interdigitated
(unlike skeletal striated muscle which has single, long cells)
What are intercalated discs?
Boundaries on either side of the cardiac muscle - connect each cardiac muscle together
(acts as a wave)
Cell membranes interdigitate
What are the 2 important components (proteins) of intercalated discs?
Desmosomes
Gap junctions
What is the function of desmosomes?
Proteins designed to bind cells together for STRENGTH
Prevention of tearing apart of cells
What is the function of gap junctions?
Allow for electrical impulses to transfer
low resistance transfer of electricity in the form of ions
What do the intercalated discs allow the heart to function as?
A functional syncytium (individual cells come together to function as one unit).
Important for allowing depolarization of the heart and evacuation of blood.
Repair of damage of cardiac cells occurs almost entirely by ___
fibrosis (scar tissue)
Metabolism requires what 3 things?
- Extensive blood supply
- High myoglobin (O2 storage)
- Creatine kinase (Cr phosphates) CK
Metabolism relies almost exclusively on ____ respiration
Aerobic
What substrates are used for producing aerobic respiration?
Glycogen/glucose Lactic acids Amino acids Ketone bodies (usage of substrates fluctuates)
The heart is highly susceptible to ___
ischemia
the heart really needs O2
T/F There is very limited use of anaerobic pathways in the heart?
True!
Which of the following structures allow one cardiac cell to electronically stimulate another by allowing ion flow across the intercalated disk? A. T-tubules B. gap junctions C. desmosomes D. intercellular folds
B. gap junctions
Describe the pathway of the depolarization of the conduction system
- Depolarization at SA node in RA
- Moves across RA and LA
- Comes to AV node (delay - allows contraction of atria and complete filling of ventricles)
- AV valve depolarizes - enters the AV bundle (Bundle of His)
- Interventricular septum
- R & L Bundle branches
- Out and around through Purkinji fibers
- Papillary muscles
What is the natural pacemaker of the heart? What is its intrinsic rate?
SA node
Rate of 100-110 bpm
(relatively independent)
What modifies the intrinsic heart rate of the SA node?
Vagal tone - through the medulla oblongata
Reduces rate to 60-80 bpm
What specific drug did Mace mention that alters the intrinsic rate of the heart?
Digitalis - blocks the intrinsic rate - depending on if the drug is in a therapeutic range or toxic range - will determine if it increases or decreases vagal tone
T/F Contraction and depolarization are the same thing
False!!!
Can have a depolarization that DOES NOT result in a contraction
Do depolarization and contraction occur at the same time? What does this mean when you are interpreting an EKG?
NO! They occur at different times
EKG = electrical activity - depolarization! NOT contraction (depolarization is followed by contraction)
What is the cardiac center?
Medulla oblongata - houses cardio-acceleratory and inhibitory center
Does NOT initiate heartbeat
SA nodal activity leads to ____
autorhythmicity
What are the steps of the SA nodal activity pathway
- Reaching threshold - SLOW voltage-gated Na+ channels open. Slow inflow of Na+ changes membrane potential from -60mV to -40 mV
- Depolarization - FAST voltage-gated Ca2+ channels open. Inflow of Ca2+ changes membrane potential from -40mV to just above 0mV
- Repolarization - FAST voltage-gated Ca2+ channels close. Voltage-gated K+ channels open allowing K+ outflow. Membrane potential return to -60mV. Voltage gated K+ channels close