Cardiovascular system

pulmonary circulation

delivers blood from heart to lungs and back to heart

peripheral circulation

delivers blood from heart to body and back to heart

arteries

large vessels that carry blood away from heart to lungs or periphery

arteriole

small, branch arteries 

capillaries

smallest vessels; sites of gas and nutrient exchange

veins

vessels that carry blood toward heart

venules

small veins that carry blood toward heart

venous blood

blood returning to heart

arterial blood

blood leaving heart and going to body or lungs

what are the four chambers of the heart?

two atria: upper chambers

two ventricles: lower chambers 

what are the four one-way valves?

two atrioventricular

• tricuspid (R) 

• bicuspid (L) 

two semilunar 

• pulmonary (R) 

• aortic (L) 

what is the pericardium?

tough membranous sac that encases heart

describe the flow of blood through the heart.

1. blood enters right atrium from superior and inferior vena cava 

2. passes through tricuspid valve into right ventricle 

3. is pumped through valve into pulmonary trunk 

4. passes through pulmonary arteries to lungs

5. is oxygenated and returned to left atrium via pulmonary veins 

6. passes through through bicuspid valve into left ventricle 

7. is pumped through valve into aorta and out to body 

how is blood supplied to the heart?

coronary arteries branches off aorta and supplies blood to the heart 

• blood is fully oxygenated 

• blood pressure is highest in aorta and very high in arteries supplying heart

coronary artery branches into R and L sides 

what is anastomosis?

intercommunication between two arteries ensuring blood flow to an area even if one artery is blocked 

All major arteries and two veins of the heart are on the outer surface of the heart, so that they are not compressed during contraction

systole

contraction phase; blood is pumped out of chamber

diastole

relaxation phase; blood fills chamber

what all is involved in the intrinsic control of the cardiac cycle?

• autorhythmicity: ability of cardiac muscle tissue to initiate impulse for contraction at regular intervals 

• sinoatrial node: pacemaker of cardiac contraction made up of specialized nervous tissue; initiales atrial contraction/systole 

• atrioventricular node: delays impulse by 1/10 of a second, allowing atria to contract before ventricles 

• purkinje fibers: rapidly spreads impulse to contract ventricles in a synchronized pattern 

what all is involved in extrinsic control of the cardiac cycle?

• parasympathetic nerve fibers: decrease heart rate 

• sympathetic nerve fibers: increase heart rate 

• endocrine glands: epinephrine from adrenal gland increases heart rate 

• bradycardia: slow heart rate; often training-induced

describe the abilities and structures of cardiac muscle (myocardium) 

• capable of contraction and force generation, like skeletal muscle 

• capable of initiating impulse (autorhythmicity) 

• has intercalated discs: leaky portions of the membranes that separate cardiac muscle fibers, allowing impulse to spread and contraction to occur

• syncytial contraction: myocardial muscle fibers contract simultaneously 

  • unlike muscle, myocardial muscle fibers do not have types (eg, I or II). Instead, just one type with: 

    • high mitochondrial density

    • extensive capillary network

    • use aerobic energy for contraction

what is the thickness of the cardiac wall proportional to?

the force 

which ventricle has greater wall thickness and why?

left ventricle; it has more myocardial muscle because it needs to supply blood to the whole body 

regular physical training and chronic hypertension will result in:

• thickening of L ventricle wall

• increase in L ventricular mass

T or F: athletes can have a L ventricular mass that is above normal limits relative to body mass.

False; altho they will have a greater L ventricular mass it will be w/n normal limits. This is however, not true of increased L ventricular mass in pathological conditions 

can training increase the thickness in the atria or R ventricle?

most studies have shown that training will not increase eithers thickness, but there may be an increase in R ventricle size in elite athletes 

what is an Electrocardiogram (ECG)?

• measures movements of ions during muscle contraction and relaxation 

• electrical activity coincides with contraction and relaxation of heart chambers 

• height of wave represents amount of electrical activity and coincides with amount of cardiac muscle contraction and relaxation 

• horizontal length of wave (x-axis) represents time; shorter amount of time for that wave to occur

describe the different waveforms of an ECG.

• P wave: atria contraction/depolarization

• following P wave, pause due to AV node 

• QRS complex: ventricular contraction/depolarization (atrial relaxation/repolarization occurs during this time but is obscured by ventricular activity) 

• T wave: ventricular relaxation/repolarization 

what does a depressed ST segment during an exercise stress test indicate?

myocardial ischemia (insufficient oxygen) often due to plaque build-up in coronary blood vessels 

and increase OR decrease in the PR segment indicates what?

abnormal AV node function

describe heart rate variability.

• beat-to-beat variation in heart rate or R-R interval timing

• indicates autonomic nervous system function

• measured thru time domain or frequency domain analysis

• monitored during short (5 min) or long (24 hr) periods

from a clinical standpoint, what does an increased HRV mean?

associated with improved autonomic function; observed after aerobic/concurrent training; common in trained athletes 

from a clinical standpoint, what does a decreased HRV mean?

linked to various diseases; indicates stress, fatigue, overtraining; used to monitor training status and recovery

what are some of the monitoring considerations that need to be taken when going to measure HRV?

time of day, training status, age, sex, cardiorespiratory fitness level

stroke volume

amount of blood pumped per contraction of ventricles

describe cardiac output.

amount of blood pumped per minutes (L*min6-1 or mL*min-1) 

determined by heart rate (HR) and stroke volume (SV)

Q: HR(bpm) X SV(mL)

what is the typical cardiac output for men? women?

men: 5 L*min^-1

women: 4.5 L*min^-1 

T or F: resting cardiac output is about the same in trained vs untrained ppl

True

people with a lower _____ will have a higher stroke volume

heart rate

changes in ____ and ____ during exercise affect cardiac output.

heart rate, stroke volume

explain how cardiac output is regulated?

heart rate affects cardiac output directly

stroke volume

• end-diastolic volume (EDV): blood in ventricles at end of diastole (if increases, SV increases) 

• end-systolic volume (ESV): blood in ventricles at end of systole 

• SV (mL) = EDV (mL) - ESV (mL) 

Ejection fraction (EF): ratio of the amount of blood available to be pumped to the amount of blood actually pumped

• EF = SV/EDV

what is the Frank-Starling mechanism and how does it relate to regulation of cardiac output?

increased venous return stretches or “preloads” the ventricle, causing reactionary increase in contractile force of ventricle. This results in lower ESV. 

• increased muscle fiber lengths also make myocardium more sensitive to intracellular Ca2+, increasing contraction force 

of the blood pressure in aorta increases, ____ decreases.

Stroke Volume 

what occurs if the blood pressure in an artery is high?

EF into the artery can decrease. To overcome high blood pressure and increase EF, heart would have to work harder; if blood pressure is too high (hypertension), heart may not be able to supply sufficient oxygen, causing ischemia

how can exercise training affect bp?

helps to decrease blood pressure and increase volume of ventricles → preventing issues that may arise from high bp

an increase in blood pressure will result in what?

a decrease in stroke volume 

how does endurance training affect end-diastolic volume and what consequences does that change result in?

increases EDV, thus increasing stroke volume and decreasing heart rate 

how does endurance training affect plasma volume and what are the cascading effects?

increases plasma volume, which may increase ventricle filling and therefore force of contraction by Frank-Starling 

what are some other ways that SV could increase?

increased ventricular contractility; therefore, ESV may also decrease 

in moderately trained or untrained people:

SV increases w exercise intensity up to 40-50% of peak oxygen consumption 

SV does not increase at greater intensities 

HR increases w cardiac output to maximal workloads; thus HR is a good indicator of training intensity 

during exercise we see a slight _____ in the steepness of the graph of cardiac output

decrease

explain the left ventricular SV changes from exercise.

endurance training, increase in L ventricle EDV (13.8mL) 

• due to increase in EDV and wall thickness 

resistance training, smaller increase (3.9 mL) 

• due only to increase in wall thickness 

• partly why resting HR changes very little with strength training 

in both scenarios, adaptations allow heart to handle higher peripheral blood pressures during activity (such as high blood pressure during resistance exercise) 

describe the other measures of systolic function.

average blood flow out of a cardiac chamber

peak rate of flow out of a cardiac chamber 

muscle fiber shortening velocity 

describe the measures of diastolic function.

essentially the same as systolic except related to the rate at which a chamber fills with blood during diastolic phase 

how do endurance and resistance training relate to systolic and diastolic functions

endurance: often show to increase these measures

resistance: little to no change in these measures 

what are the two basic functions of the cardiovascular system?

• deliver essential substances (oxygen and nutrients) to tissue 

• remove metabolic by-products (carbon dioxide, lactate) from tissue 

what are the laws that govern the flow of blood w/n the cardiovascular system?

blood flows from area of high pressure to area of lower pressure 

rate of flow is proportional to pressure difference between two ends of vessel or between two chambers 

• thus, increase in pressure difference increases flow 

blood flow: change in pressure/resistance to flow 

• thus, decreasing resistance increases flow 

increase in radius of vessel increases flow 

decreasing blood viscosity increases flow 

the highest bp occurs during:

systole, this is called the systolic blood pressure

the lowest bp occurs during:

diastole, this is called the diastolic blood pressure 

how is bp measured?

w/n the brachial artery with sphygmomanometer and stethoscope

what is the typical bp?

120/60

what happens to the bp as blood travels down to smaller and smaller branches of blood vessels.

decreases, thus low in capillaries but high enough to exert pressure here

what does increases cardiac output during exercise do to bp?

increases bp

what factors concerning the peripheral arteries would result in a decreased bp? Why would these decrease bp?

increases capacitance, elasticity, and compliance will decrease bp as it allows them to expand when blood is ejected into them.

what type of training mainly attributes to increased capacitance in peripheral arteries?

endurance training, not rlly seen in RT 

T or F: combined training will increase compliance, thereby negating any decreases that may occur in RT

True 

what is an important trait for the peripheral arteries have in regards to maintaining good health?

increased compliance 

T or F: both aerobic and weight training can reduce resting bp in normotensive (normal bp) and hypertensive (high bp) individuals  

True! and it will reduce both resting bp and bp at a given intensity of exercise 

explain what hematocrit is.

percentage of total blood volume composed of formed elements

• acutely, hemoconcentration increases during exercise 

• altho plasma volume increases as a long-term adaptation to training, red blood cells increase as well, so there is a slight decrease in hematocrit 

explain what plasma is.

fluid component: 90% water, 7% plasma proteins, 3% other 

55-60% of total blood volume 

may decrease in volume as much as 10% during intense physical activity 

can increase as much as 10% at rest because of adaptation to training or acclimatization to hot, humid environments 

in athletes, total blood volume increases to deal with increased demands for blood 

explain what the formed elements are?

make up 40-45% of blood

red blood cells: 99% 

white blood cells and platelets: 1% 

platelets 

• important for blood clotting 

• contribute to heart attack, stroke, plaque buildup 

describe the functions of red blood cells in the cardiovascular system?

transport oxygen via hemoglobin

hemoglobin: protein (globin) and iron-containing pigment (heme) necessary for binding oxygen 

in adults, produced in bone marrow of long bones 

nuclei are removed from RBCs when produced, and thus, they can’t repair themselves 

lifespan of 4 months

destruction and production are balanced 

what happens do plasma volume with the onset of aerobic or weight training acutely? 

substantial reduction of plasma volume as increased BP forces fluid, but not cellular components of blood, out of vascular system; results in hemoconcentration

adaptation is to increased number of RBSs per unit volume of blood, thereby increasing oxygen-carrying capacity (esp during exercise and at altitude) 

what is hemoconcentration?

a greater concentration of hematocrit that is observed during exercise as the volume of plasma in the blood decreases

what effect can prolonged aerobic exercise have on plasma volume?

a decrease of 10-20%

what is the acute effect of weight training on plasma volume?

a decrease of 0-22%

what is the chronic effect of long-term aerobic training on plasma volume?

plasma volume increases 12-20%, this results in increased EDV,SV, and Q, improved blood transport and performance, temperature regulation

what is the difference in plasma per hematocrit in untrained vs trained individuals?

untrained: plasma: 55% and hematocrit: 45%

trained: plasma: 58% and hematocrit: 42%

what are some adaptations of the cardiovascular system we see due to endurance training?

increased Q 

increased oxygen delivery to muscle 

increased endurance performance 

what are some adaptations of the cardiovascular system we see in resistance trained individuals?

increased ability to maintain cardiac output against the increased blood pressures encountered during resistance exercise

describe how oxygen is delivered to the tissues during exercise.

blood flow increases during exs for delivery (oxygen, glucose, triglyceride) and removal (carbon dioxide)

oxygen delivery depends on: 

• amount of oxygen tissue takes out of blood flowing thru it 

• amount of blood flowing thru tissue 

at rest, both of the above factors somewhat constant, but amplified during exs

what is arterial-venous oxygen difference (a-vO₂ diff)

amount of oxygen per 100mL of arterial blood entering a tissue minus that leaving tissue and the amount of oxygen in 100 mL 

increased during exercise 

what is arterial-mixed venous oxygen difference?

diff b/w blood leaving L ventricle and venous blood entering R atrium 

reps diff for all body’s tissues (metabolically active and inactive) 

at rest: 5mL O₂ per 100mL blood 

exercise: 15 mL O₂ per 100 mL blood 

only one aspect of oxygen delivery (bc of delivery affected by blood flow) 

what is the fick equation?

oxygen delivery = blood flow X a - vO₂ diff

how can oxygen consumption for the whole body be calculated?

VO₂ = oxygen consumption

cardiac output (Q) = blood flow

VO₂ = Q x a - vO₂ diff

how can we increase VO₂ (oxygen consumption) for the whole body? 

increasing Q or a - vO₂ 

explain the redistribution of blood flow during exercise.

at rest: 15-20% of cardiac output goes to skeletal muscle 

during maximal exercise: 80-85% goes to skeletal muscle 

blood flow increases to skin (dissipate heat) 

myocardial blood flow increases four due to an increase in Q 

blood flow to brain increases 25% 

what are the factors that affect the redistribution of blood?

parallel circuitry (blood flows to all organs w/o the need to pass thru another tissue or organ first) 

• allows blood flow to be increased or decreased to specific organs and tissues

vasodilation: increase in radius of vessels (less resistance to flow, increase blood flow to tissues) 

vasoconstriction: decrease in radius of vessels (more resistance, forcing blood to flow to other tissues) 

precapillary sphincters: muscular rings at entrance of capillary bed; react to local changes by constricting or relaxing, therefore controlling flow to tissues

describe the extrinsic control of vasoconstriction and vasodilation.

release of norepinephrine by sympathetic nerves causes: vasoconstriction of peripheral blood vessels

release of epinephrine by sympathetic nerves can cause both vasoconstriction and vasodilation

at rest, vasoconstriction to muscle (vasodilation w exs)

w exs, sympathetic vasoconstriction to inactive tissue (intestines, liver, kidneys)

describe the intrinsic control of vasoconstriction and vasodilation.

autoregulation: changes in skeletal muscle during exs that stimulate smooth muscle chemoreceptors in precapillary sphincters and increase vasodilation

vasodilation balanced with sympathetic stimulation to ensure adequate blood flow to heart and brain

what are three ways to increase venous return?

venoconstriction, muscle pump, respiratory pump

explain how venoconstriction can increase venous return.

constriction of veins via sympathetic stimulation 

veins contain 65% of blood volume, so they act at storage reservoirs or capacitance blood vessels

only effective in tissues other than skeletal muscle

explain how muscle pumping can increase venous return.

rhythmic muscle contractions propelling blood to heart through one-way valves of the veins (preventing backflow and ensure that blood, when pumped, moves toward heart)

explain how respiratory pumping can increase venous return.

changes in intrathoracic and intra abdominal pressure during expiration and inspiration. forcing blood in those cavities to flow toward heart 

describe how there is an increase in oxygen delivery during exercise.

increase O2 delivery to active muscle requires increased Q, redistribution of blood flow, and increased a-Vo2 diff 

adaptation to endurance training: increases in capacities for these 

vasodilation increases blood flow (and O2 delivery) to active tissues (muscle) but decreases BP 

vasoconstriction in inactive tissue decreases its blood flow but increases blood pressure 

with increased intensity, increases in heart rate and stroke volume causes increased Q 

endurance training adaptation: increased stroke volume w/o increase in max heart rate; decreased heart rate at a given intensity