Physiology of the cardiovascular system Flashcards
What is the conduction system of the heart
- Sinoartial node
- atrioventricular node
- bundle of his
- right and left bundle branches
- purkinjie fibers
What is the pacemaker of the heart
- SA node
What other elements of the heart can contract on their own
- AV node (slower only 40-60 beats)
- myoctyes but one 20-40 beats and they would not coordination
- can contribute to arrthymias
Coronary circulation
- when does blood flow get pushed into circulation/when does perfusion occur
- blood flow Is pushed into the coronary arteries at the end of systole
- perfusion occurs at the capillary level during diastole
- Where do each provide blood supply
1. posterior circumflex
2. left coronery artery
3. anterior descending branch of left coronary artery
4. right coronary artery
- left atrium and posterior wall of L ventricle
- to the left side of the heart
- septum and anterior wall of left ventricle
- SA node and AV node area
Systemic circulation (how does it work)
- arterial pressure drives blood into tissue
- perfusion occurs at capillary level
- venous system is very low pressure return system
What is the overall role of the heart
- carries O2, hormones, sugar, waste, platelets
WBCs - impacts every system
- not good pumping = not good exercise tolerance
What characteristics of the heart allow the heart to pump blood on its own
the ability to pump blood is opened on the following
- automatic: own impulse
- rhythmic: repeat and cannot take a break
- excitable: each cell needs to respond
- conductive: from cell to cell
- contractile: different cells contract in different ways with different amount of squeeze
Describe the cardiac cycle following 1 blood cell
- venous return to the right atrium
- venous flow arrives in the right ventricle
- venous blood is sent in the lung via pulmonary artery
- after oxygenation in the lung the blood returns to the left atrium
- red blood arrives in the left ventricle
- re blood is sent in the arteries to the tissues
Isovolumeric contraction
- both valves are closed and the heart is starting to squeeze
- isovolumeric relaxation
- both valves are closed and the muscle is relaxing
End diastolic pressure and volume
- pressure/volume at the end of distal
Cardiac cycle with both atria and ventricles not following 1 RBC
- atria systole: atria contract, Av valves open, SL valves closed
- early ventricular systole: atria relax, ventricles contract, AV valves forced closed, SL valves still closed
- Late ventricular systole: atria relax, ventiles contract, AV remains closed and SL valves forced open
- Early ventricular diastole: atria and ventricles relax, AV valves and SL valves closed atria begin passively filling with blood
- late ventricular diastole: atria and ventricles relax, atria passively fill with blood as AV valves open SL valves close
What is the cardiac cycle a series of
- pressure changes that take place within the heart
- these pressure changes result in the movement of blood through different chambers of the heart and body as a whole
What is Cardiac Output
- The quantity of blood pumped in one minute
- CO = HR x SV
what type of factors affect HR/examples of factors
- chronotropic (time)
- automonic innervation
- Hormones
- Fitness level
- Age
what type of factors affect SV
- ionotropic = contraction
- Factors that affect SV
- Heart size
- Fitness level
- Gender
- Contractility
- Duration of contraction
- Preload (EDV)
- Afterload (resistance
What does SV =
- EDV - ESV
(end filling volume - what is left after contraction)
How does CO respond to exercise
- CO increases
- SV capacity if limited - the heart can only hold a fixed volume
- SO largest contribution to CO is heart rate
what is ejection fraction
- An indicator of pump function
- It is a percentage of blood ejected from ventricles
What does EF =
- amount of blood ejected from ventricle (SV)/ total amount of blood in ventricle (EDV)
What is the normal value for EF and then what do other categories mean?
- Normal EF is 50-70 %
- Borderline: 41-49%; Symptoms may only be noticeable during moderate activity
- Reduced ≤40% Symptoms may be noticeable during rest
What is preload
- Volume coming into ventricles (EDV)
- Certain volume for stretch on muscle for it to contract → similar to length tension in Skeletal muscles
when is preload increased
- Increased in
- Hypervolemia
- Regurgitation of cardiac valves (backflow)
What is after load
- pressure
- Resistance the left ventricle must overcome to circulate blood/open the aortic valve
How can afterload be increased
- hypertension
- Vasoconstriction
- Increase in afterload = increase in cardiac workload
Where does the sympathetic NS have neural input within the cardiovascular system and what affect does it have on the heart
- Arteries
- Veins
- Heart
- Bronchi
- Chronotropic and inotropic = effects HR and contractility
Where does the parasympathetic NS have neural input
- Heart
- Abdominal blood vessels
- Chronotropic
What is integrated to make up heart rate in cardiac function?
- Central nervous system
- Autonomic nervous system
- Neural reflexes
- atrial receptors
- Hormones
What has an effect on Stroke volume
- preload
- afterload
- contractility
What effects preload
ESV
Venous return
What effects afterload
- Aortic pressure
- Aortic valvular function
What effects contractility
EDV
Sympathetic stimulation
Myocardial oxygen supply
What is systemic circulation depended on
blood supply
What influences systemic circulation
- heart /CO
- Total peripheral resistance
- Vessel tone, length, radius, blood viscosity, blood volume
What makes up Bp
- COxTPR
