the cardiovascular system and its control Flashcards
what are the 3 major circulatory elements of the cardiovascular system
- a pump (heart)
- channels or tubes (blood vessels)
-a fluid medium (blood)
what are the major functions of blood
- delivers 02 nutrients
-removes CO2, other waste - transports hormones, other molecules
- temperature balance and fluid regulation
what are the 4 chambers of the heart and where are they located?
right and left atria (RA,LA): top receiving chambers
right and left ventricles (RV, LV): bottom, pumping chambers
what circulation does the right heart do ?
pulmonary circulation
what circulation does the left heart do?
systematic circulation
the right heart pumps ___ blood from ___ to ___
deoxygenated, body, lungs
the left heart pumps _____ blood from ____ to ___
oxygenated, lungs, body
what is the order of blood from the right heart?
Superior, inferior vena cavae ->RA -> tricuspid valve ->RV -> pulmonary valve -> pulmonary arteries -> lungs
what is the order of blood from the left heart ?
Lungs -> pulmonary veins -> LA ->mitral valve -> LV -> aortic valve -> aorta
myocardium itself needs ___
blood
what side of the heart does the right coronary artery supply?
right side of heart
what side of the heart does the left (main) coronary artery supply ?
the left side
what is myocardium?
cardiac muscle
what are the left ventricle characteristics?
-pumps blood to entire body
-thickest walls (hypertrophy)
-LV hypertrophies with exercise and with disease
- exercise and disease adaptations are different
skeletal muscle cells characteristics?
- large, long, unbranched, multinucleated
-intermittent, voluntary contractions
-Ca2+ released from SR
what are the myocardial cells characteristics ?
-small, short, branched, one nucleus
-continuous, involuntary rhythmic contractions
- calcium- induced calcium release
what type and the characterisics of myocardial cell fiber?
-only one fiber type
-high number of mitochondria
-striated
Cardiac muscle fibers connected by regions called ____
intercalated discs
what are desmosomes ?
hold cells together
what are gap junctions?
rapidly conduct action potentials
what are the steps to the calcium induced release ?
1.AP spreads along sarcolemma down T-tubules
2.DHP receptors (a special Ca2+ channel) in T-tubule are stimulated and open
3.Ca2+ to enter cell, but insufficient to cause contraction
4.Instead, triggers ryanodine receptors (another special Ca2+ channel) on SR to release Ca2+
what causes the heart to beat ?
-Contraction is caused by electrical stimulation of the heart tissue.
-Electrical impulse:
Right atrium -> throughout the entire heart.
-Starting point : Sinoatrial node (SA node)
What are the components involved in the intrinsic control of heart activity and responsible for generating and spreading electrical signals?
Sinoatrial (SA) node
Atrioventricular (AV) node
AV bundle (bundle of His)
Purkinje fibers
How does the electrical signal spread in the intrinsic control of heart activity, and what is the intrinsic heart rate observed in certain patients?
The electrical signal spreads via gap junctions.
The intrinsic heart rate (HR) is observed to be 100 beats/min.
This phenomenon is observed in heart transplant patients due to the absence of neural innervation.
how does the SA node initiate contraction signal for the cardiac conduction system?
-Pacemaker cells in upper posterior RA wall
-Signal spreads from SA node via RA/LA to AV node
-Stimulates RA, LA contraction
how does the AV node delays, relays signals to ventricles?
-In RA wall near center of heart
-Delay allows RA, LA to contract before RV, LV
-Relays signal to AV bundle after delay
What are the functions and characteristics of the AV bundle within the cardiac conduction system?
-The AV bundle relays signals to the right ventricle (RV) and left ventricle (LV).
-It travels along the interventricular septum.
-The AV bundle divides into right and left bundle branches.
-It sends signals toward the apex of the heart.
What are the characteristics and functions of Purkinje fibers in the cardiac conduction system?
-Purkinje fibers send signals into the right ventricle (RV) and left ventricle (LV).
-They are terminal branches of the right and left bundle branches.
-Purkinje fibers spread throughout the entire ventricle wall.
-Their main function is to stimulate the contraction of the RV and LV.
what is the order of the cardiac conduction system?
SA node, AV node, AV bundle/bundle of his, bundle branches, purkinje fibers
what are the parasympathetic control functions and characteristics when it comes to the extrinsic control of heart activity ?
-Decreases force of contraction
-Decreases HR below intrinsic HR
-Intrinsic HR: 100 beats/min
-Normal resting HR (RHR): 60 to 100 beats/min
-Elite endurance athlete: 35 beats/min
what is the function of the sympathetic nervous system and charcterisics whenit comes to the extrinsic control of heart activity?
-Increases force of contraction
-Increases HR above intrinsic HR
-Determines HR during physical, emotional stress
-Maximum possible HR: 250 beats/min
how does ecg record the hearts electrical activity ?
-10 electrodes, 12 leads
-Different electrical views
-Diagnostic tool for coronary artery disease
what are the 3 basic phases of the ecg?
-P wave: atrial depolarization
-QRS complex: ventricular depolarization
-T wave: ventricular repolarization
what are some examples of cardiac arrythmias?
(B,T,P,A,Vt,Vf
Bradycardia (pathological vs. exercise induced)
Tachycardia (pathological vs. exercise induced)
Premature ventricular contraction
Atrial flutter, fibrillation
Ventricular tachycardia
Ventricular fibrillation
what are the terminology of cardiac function?(H,Cc,Ef,Co)
-Heart rate (bpm)
-Cardiac cycle
-Stroke volume (ml/beat)
-Ejection fraction
-Cardiac output (Q* L/min)
CO-what is the formula for total volume of blood pumped per minute?
CO (Q) = HR X SV
what is the cardiac output at rest ?
-HR ~70 beats/min
-SV ~70 mL/beat
-70 beats/min x 70 mL/beat = 4,900 mL/min
-Use L/min (4.9 L/min)
resting cardiac output is 4.2 to 5.6 L/min what is the average total blood volume and how many times does the tbv circulate in a min?
5L and once every min
What are the key components and phases of the cardiac cycle? (systole and diastole)
-All mechanical and electrical events occur during one heartbeat.
-One cycle consists of one contraction and one relaxation, equivalent to one full beat of the heart.
-There are two phases: Systole, which is the contraction phase responsible for ejecting blood, and
-Diastole, the relaxation phase responsible for filling the heart with blood.
What occurs during ventricular systole in the cardiac cycle, and what is the significance of end-systolic volume (ESV)?
-Ventricular systole accounts for 1/3 of the cardiac cycle time.
-It involves the ejection of blood from the ventricles.
-During systole, while blood is ejected out, some remains in the ventricle, which is termed end-systolic volume (ESV).
What characterizes ventricular diastole in the cardiac cycle, and what is the significance of end-diastolic volume (EDV)?
-Ventricular diastole: 2/3 of cardiac cycle time
-Fill 70% passively, remaining 30% by atrial contraction
-At end, blood in ventricle = end-diastolic volume (EDV)
what is stroke volume?
volume of blood pumped in one heartbeat
what is the formula for stroke volume ? and give an example
EDV – ESV = SV
Ex) 100 mL – 40 mL = 60 mL
what is ejection fraction
% of EDV that was SV
SV / EDV X 100 = EF (%)
what is an example of ejection fraction?
-60 mL/100 mL = 0.6 x 100 = 60%
-Normal for healthy, active young adult at rest: 50 – 70%
-Clinical index of heart contractile function
Heart failure : ≤ 40%
what are the 3 factors that control stoke volume? (P,C,A)
-preload
-contractibility
- afterload
What is the primary determinant of stroke volume according to the Frank-Starling mechanism? (P)
preload- end diastolic volume (EDV)
What is the term for the pressure that the heart must overcome to eject blood, and what is its primary determinant in regulating stroke volume? (A)
- afterload
-the average aortic blood pressure
What factor determines the strength of ventricular contraction, is independent of stretch, and is enhanced by circulating epinephrine and norepinephrine? (C)
contractibility
what is preload?
volume of blood in ventricles at end of diastole (end diastolic pressure)
what is preload increased in ? (Hv,Rocv,Hf)
hypervolemia
regurgitation of cardiac valves
heart failure
what is afterload?
resistance left ventricle must overcome blood
what is afterload increased in? (Ht,V)
hypertension
vasoconstriction
what is preload in regulation of stroke volume ?(EDV) (FSM)
end diastolic volume
frank starling mechansim
what is afterload in regulation of stroke volume?
average aortic blood pressure
what is contractility of regulation of stroke volume?
strength of the ventricular contraction
how does EDV (preload) impact SV? (FSM)
frank starling mechanism
what is the frank starling mechanism
the more the ventricles are “stretched” (i.e. greater EDV), the more forceful the contraction
what is the order in the regulation of EDV?
(Vr->CEDV->CSV)
venous return->controls EDV-> controls SV
what factors influence HR?
(Ac, H/C,Bt,A)
-autonomic control-sympathetic and parasympathetic
-hormones/chemicals:epi, norepi
-body temperature
-emotions
-age
what is resting HR?
average 60 to 80 Bpm
tends to decrease with age and increase CV fitness
what is maximum HR ?
-highest HR values one can reach in an all out effort
-HRmax=220-age
What is cardiovascular capacity (VO2)
ability of the heart, blood cells and lungs to supply o2 rich blood to the working muscle tissues and the ability of the muscles to use o2 to produce energy for movement
what determines o2 consumption (VO2) by tissues? (Fp)
fick principle “O2 consumed=O2 delivered - O2 returned
what is the formula for cardiac output ?
CO=HR x SV
what is a-v02diff?
02 uptake by tissue
arterial O2- venous O2
what is maximum o2 consumption (VO2) formula?
VO2max=COmax x a-vO2diffmax
why is exercise good for brain perfusion?
(Cbf, Nc,Ca)
increases cerebral blood flow
neurovascular coupling
cerebral autoregulation
what is a intsrument for the brain? (Tcd)
transcranial doppler
what do arteries do?
carry blood away from heart
what do arterioles do ?
control blood flow, feed capillaries
what do capillaries do?
site of nutrient and waste exchange
what do venules do?
collect blood from capillaries
what do veins do ?
carry blood from venules back to heart
what is systolic pressure ? and what does it range from ?
highest pressure in artery (during systole)
top number, 110 to 120 mmHg
what is diastolic pressure? and what does it range from
lowest pressure in artery
bottom number, 70-80 ,mmHg
what is mean arterial pressure ? and what is the formula?
-average pressure over entire cardiac cycle
-MAP=(SBP-DBP)1/3+DBP
what are the integrative control of blood pressure ? Br
baroreceptors
what are the functions and characteristics of baroreceptors? (S,A,E,A)
-sensitive to changes in arterial pressure
-afferent signals from baroreceptors to brain
-efferent signals from brain to heart and vessels
- adjust HR and arterial pressure back to normal
-BP=CO x TPR
what is the formula for blood flow when it comes to general hemodynamics?
blood flow= pressure/resistance
pressure is the force that drives flow, what are the characteristics ? (P,B,P)
-provided by heart contraction
-blood flows from regions of high pressure (LV, arteries) to region of low pressure (veins, RA)
-pressure gradient = 100 mmHg-0 mmHg= 100mmHg
resistance is the force that opposes flow, what are the characteristics? (P,R)
-provided by physical properties of vessels
-radius most important factor: VC,VD
what is poiseuille’s law
Q=pi Pr^4/ 8nl
what is the easiest way to change flow->change R? (VC or VD, D)
-vasoconstriction or vasodilation
- diverts blood to regions most in need
arterioles are known as resistance vessels what does it do with R? (C, S)
-control systemic R
-site of most potent VC and VD
when it comes to the distrubution of blood, the blood flows to where needed most, regions of increased ____ to increased ____ flow? (M, B)
metabolism, blood flow
what is Q at rest ?
Q=5 L/min
what percentage of Q do liver and kidneys receive?
50% of Q
what percentage of Q do skeletal muscle need ?
20% of Q
what is Q during heavy exercise?
Q=25 L/min
what percentage of Q do exercising muscles receive and from VD or VC, and where does it flow and decreases via VD or VC?
80% of Q via VD
flow to liver, kidneys decrease via VC
arteriole walls can respond to ________?
(Lcm)
local control mechanisms
what is intrinsic control ? (A,A)
-ability of local tissues to constrict or dilate arterioles that serve them
-alters regional flow depending on need
what are the metabolic mechanisms (VD) when it comes to the intrinsic control of blood flow ?
(S,B) and what is an example ? (FMD) what decreases and what increases ? (o, C,K,H,La)
-strongest stimulus for release of local VD chemicals
-buildup of local metabolic by products:
ie flow mediated dialted
- decrease O2
- increase CO2, K+,H+, lactic acid
what is the endothelial mechanisms (mostly VD) when it comes to the intrinsic control of blood flow? (S,Emv)
-substances secreted by vascular endothelium(arterole inner lining )
-endothelium mediated vasodilation
