exercise phys exam 3

functions of the circulatory system

transport O2 and nutrients

remove CO2 and wastes

regulate temperature

exercise adjustments of the circulatory system

increased cardiac output and redistribution of blood flow

what does the heart do

creates pressure to move blood through the circulatory system

what do the arteries do?

carries blood away from heart

what do veins do

return blood back to heart

what do capillaries do

allow exchange of oxygen, nutrients, and wastes between blood and tissues

blood flow pathway from body

body → vena cava → right atrium → right ventricle → pulmonary arteries → lungs → pulmonary veins → left atrium → left ventricle → aorta → body

pulmonary circulation

right heart to lungs via pulmonary arteries for gas exchange and returns by pulmonary veins to the left heart

systemic circulation

blood flows from left heart to body via arteries and returns to right heart by veins

which vessels return blood from lungs to heart

pulmonary veins

which side of the heart pumps blood to the lungs

the right side

which side of the heart pumps blood to the body

the left side

which circulation carries oxygen poor blood to the lungs

pulmonary circulation

which circulation delivers oxygen rich blood to body tissues

systemic circulation

layers of the heart wall

epicardium, myocardium, endocardium

what is the myocardium

the muscular layer of the heart responsible for contraction

what do coronary arteries do

supply heart muscle w oxygenated blood

how does myocardial infarction (heart attack) occur

results from blocked coronary blood flow

how is regular exercise beneficial to heart

improves cardiovascular health and reduces cardiovascular disease risk

what is systole

contraction/ejection of blood

highest arterial pressure during ventricular contraction

what is diastole

relaxation/filling of blood

lowest arterial pressure during ventricular relaxation

what happens to phases during exercise

both phases shorten, especially diastole

why is diastole important during exercise

ventricles fill and the coronary arteries receive much of their blood flow during diastole

what is normal arterial blood pressure

120/80

how to find pulse pressure

SBP (systolic) - DBP (diastolic)

how to estimate mean arterial pressure

MAP = DBP + 0.33 (SBP - DBP)

what is hypertension

> 130/80 mmHg and increases cardiovascular risk

short term regulation of blood pressure

sympathetic nervous system and baroreceptors

long term regulation of blood pressure

kidneys regulate blood volume

what do baroreceptors detect

changes in arterial pressure through stretch of blood vessel walls

how can increased total peripheral resistance affect MAP

MAP increases if cardiac output remains constant

what is the sinoatrial (SA) node

hearts natural pacemaker

what is the AV node

delays impulse so ventricles can fill before contracting

what do bundle branches and purkinje fibers do

carry electrical impulses down interventricular septum toward ventricles to coordinate contraction

normal pathway of electrical conduction through the heart

SA node → atria → AV node → bundle of His → bundle branches → purkinje fibers

what is a P wave on an ECG

atrial depolarization

what is a QRS complex on an ECG

ventricular depolarization

what is a T wave on an ECG

ventricular repolarization

what does ST depression indicate

may indicate myocardial ischemia

what electrical event triggers ventricular contraction

ventricular depolarization, represented by the QRS complex

why does blood pressure depend on cardiac output and vascular resistance

pressure rises when the heart pumps more blood per minute or when vessels resist blood flow more strongly

calculating heart rate

beats / min

calculating stroke volume

blood ejected per beat

how does training effect cardiac output

increases maximal cardiac output primarily through increased SV

parasympathetic heart rate regulation

decreases heart rate

sympathetic heart rate regulation

increases heart rate

why is there a rise in heart rate after initial exercise

due to parasympathetic withdrawal

what causes above 100 bpm

sympathetic activation

how is stroke volume regulation determined

by preload (EDV), afterload, and contractility

what is the equation for cardiac output (Q)?

Q = HR x SV

why do trained individuals have a higher maximal cardiac output

because they have a greater maximal stroke volume

how do trained and untrained individuals differ in maximal cardiac output

trained generally have a higher maximal output due to greater stroke volume

what is stroke volume? (SV)

volume of blood ejected per heartbeat

what causes the initial rise in HR at the start of exercise

parasympathetic withdrawal

what mainly increases HR above approx 100 bpm during exercise

increased sympathetic activation

what is heart rate variability (HRV)

variation in the time between consecutive heartbeats (R-R intervals)

what does HRV reflect

the balance between sympathetic and parasympathetic nervous system activity

what does high HRV indicate

healthy autonomic regulation and adaptability

what is low HRV associated with

increased cardiovascular risk

what three main factors determine stroke volume

preload, afterload, and contractility

what is preload

the degree of ventricular filling before contraction, often represented by EDV

what is afterload

the resistance or pressure the ventricle must overcome to eject blood

what is contractility

the heart muscles ability to contract forcefully at a given preload

what is the frank-starling mechanism

increased EDV stretches the heart muscle, producing a stronger contraction and greater stroke volume

how does sympathetic simulation affect stroke volume

increases contractility, which increases stroke volume

how to catecholamines affect the heart

increase heart rate and contractility

what is the muscle pump

contracting skeletal muscles compresses veins, helping return blood to the heart

how do the muscle and respiratory pumps affect stroke volume

increase venous return and preload, which can increase stroke volume

what are the 4 major components of blood

plasma, red blood cells, white blood cells, and platelets

what is hematocrit

the percentage of blood volume made up of red blood cells

what determines blood flow

pressure gradient divided by resistance

what happens to blood flow when the pressure gradient increases

blood flow increases

what happens to blood flow when resistance increases

blood flow decreases if the pressure gradient stays constant

what are the major resistance vessels

arterioles

what 3 factors affect vascular resistance

vessel length, blood viscosity, and vessel radius

which vessel characteristic has the greatest effect on resistance

vessel radius

how does decreasing vessel radius affect resistance

resistance increases

why are arterioles called resistance vessels

their small, adjustable diameters create substantial resistance and regulate blood flow

where does the largest blood pressure drop occur

across the arterioles

what happens to cardiac output as exercise intensity increases

cardiac output increases to deliver more oxygen to working muscles

how does stroke volume change during exercise

it increases, then may plateau in untrained individuals

what is the a-vO2 difference

the difference in oxygen content between arterial and venous blood

what happens to a-vO2 difference during exercise

increases as working muscles extract more oxygen from the blood

how does blood flow change during exercise

more blood is directed to working muscles

how do beta blockers affect contractility

decrease contractility and can reduce stroke volume

how can beta blockers affect heart rate

decrease heart rate by blocking sympathetic beta adrenergic effects

how can beta blockers affect exercise performance

limit the rise in HR and cardiac output potentially reducing maximal exercise capacity

what might ST segment depression during an exercise test indicate

myocardial ischemia or insufficient blood supply to the heart muscle

what is a graded exercise test

a test that progressively increases exercise intensity to evaluate cardiovascular responses and function

if HR is 150 beats/min and SV is 100 mL/beat, what is Q

15,000 mL/min = 15 L/min

if cardiac output increases while TPR stays constant, what happens to MAP

MAP increases

what is the main function of plasma

transports blood cells, nutrients, hormones, proteins, and wastes

main function of red blood cells

transport oxygen using hemoglobin

main function of white blood cells

defend the body against infection

main function of platelets

help blood clot and stop bleeding

equation for blood flow

blood flow = pressure gradient ÷ resistance

what drives systemic blood flow

mean arterial pressure relative to right arterial pressure

what is the approx right atrial pressure used in blood flow calculations

approx 0 mmHg

how much can skeletal muscle oxygen demand increase during exercise

approx 15-25 times above resting damand

what is the fick equation for oxygen consumption

VO2 = cardiac output x a-vO2 difference