Exam 3: CV Response to Exercise

1. transport O₂ and nutrients to tisssues

2. transport CO₂ and waste from tissues

3. regulation of body temp

4. nutrient, immune, and hormone transport

4 purposes of the CV system (maintenance of homeostasis)

1. maintenance of BP

2. increased CO

3. redistribution of blood flow

3 adjustments made during exercise to reach a steady state above homeostasis

L ventricle; R atrium; pressure always goes H to L

where is pressure the highest and lowest in the systemic vascular system and why is this important

capillaries

which vessels have the greatest cross-sectional area

veins

where is most of the blood at any one time

capillaries for gas exchange

where is velocity the slowest and why

same

is the CO the same or different in the pulmonary vs systemic circulations

highest in arteries and lowest in veins

where is BP the highest and lowest

arterioles

which vessels are responsible for redistribution of flow

systole and diastole

what are the two primary components of the cardiac cycle

70 mL

what is a typical resting SV of the L ventricles

55-70%; gives extra blood for exercise

what is a typical EF of the L ventricle and the significance of this

PSNS slows activity; SNS increase activity

describe the heart’s ANS innervation

cardiac tend to be more slow twitch, electrical activity passes form one cell to another

skeletal muscle: has to be innervated individually by a nerve

what are some general differences between cardiac and skeletal muscle

cardio myocytes have a higher percentage of oxygen extraction from the blood while skeletal muscle extracts a much lower percentage

compare oxygen extraction % from cardiac myocytes vs skeletal muscle

amount of blood pumped out in one minute; HR x SV; ~5L/min

what factors contribute to CO

increases

what impact does an increase in activity have on CO

diastole

at rest which is longer: diastole or systole

both shorten but diastole decreases more that systole since more time can be sacrificed during this phase; systole can only be slightly shortened d/t time it takes for ventricle to have a full contractions

describe what happens to diastole and systole during exercise

systole

during exercise which is longer: diastole or systole

epicardium

this layer of the heart is also known as the visceral pericardium and is where blood vessels are located; characterized by serous membrane including blood capillaries, lymph capillaries, and nerve fibers; function is to serve as a lubricative outer covering

myocardium

this layer of the heart is characterized by cardiac muscle tissue separated by connective tissue and include blood capillaries, lymph capillaries, and nerve fibers; function is to provide muscular contractions that eject blood from the heart chambers

endocardium

this layer of the heart is characterized by endothelial tissue and a thick subendothelial layer of elastic and collagenous fibers and its function is to serve as a protective inner lining of the chambers and valves

70-80%

the myocardium extracts this percentage of the oxygen from the coronary arteries at rest and during activity

4-6x (has capacity to meet demands of exercise)

demand increases with activity and with vigorous exercise, coronary blood flow increases this amount above rest

ventricular diastole

coronary blood flow occurs during which phase

d/t decreased ventricular diastole time which reduces coronary blood flow time to feed the heart muscle causing ischemic chest pain

explain why exercise symptoms occur before resting symptoms

lactate, amino acids, ketones

the heart utilizes which three sources of energy during exercise

fatty acids > glucose/glycogen > lactate

three sources of energy used most to least by the heart during rest

glucose/glycogen > fatty acids > lactate

three sources of energy used most to least by the heart during moderate exercise

lactate > fatty acids > glucose/glycogen

three sources of energy used most to least by the heart during intense exercise

MI

endurance training is cardioprotective against damage with which pathology

arterial BP

this value is determined by CO, total systemic peripheral resistance (TSPR), and blood volume (CO x TSPR)

BP; redistributing

major task is to maintain ________ during exercise while _____________ blood flow to exercising muscle

systolic pressure

pressure in the arteries during ventricular contraction

diastolic pressure

pressure in the arteries during ventricular relaxation

pulse pressure

this is calculated by the distance between systolic and diastolic pressures (SBP-DBP)

mean arterial pressure (MAP)

this is the average pressure in the arteries during the cardiac cycle

93 mmHg

MAP if resting BP is 120/80

SNS; kidneys (controls blood volume)

acute regulation of BP; long-term regulation of BP

HR x SV

formula for CO

CO

the amount of blood pumped by the heart each minute and the product of HR and SV

training state, gender, age

max CO depends on which three factors

~ 5 L/min

resting CO value

trained d/t increased SV so it takes longer to pump blood out and lower resting HR

which training status has the lower max HR and why

EDV

highest volume right before heart contracts

ESV

lowest volume right after heart contracts

EDV - ESV; ~ 70 mL

SV formula and resting value

55-60% at rest; (SV/EDV) x 100

EF value at rest; EF formula

linear

at a mod to high intensity HR increases in what manner

slower

training causes a _______ increase in HR during exercise

limited

SVmax is _______ in untrained vs trained

SA node activity (increases firing rate), increase temperature, decreased pH, increased PCO₂; beta-agonist medications

intrinsic regulation of HR

autonomic nervous system, endocrine system

extrinsic regulation of HR

parasympathetic tone (d/t PSNS) through vagus n.

this is responsible for low HR at rest

SNS through cardiac accelerator nerves

this is an extrinsic factor that increases HR by stimulating SA and ventricles

E/NE

the endocrine system is an extrinsic factor that regulates HR and uses which two hormones

calcium channel blockers and beta blockers

two types of medications that interfere with HR regulations and could cause HR to take longer to increase at the onset of exercise

linear

this type of relationship exists b/t HR and VO2max

HRV (heart rate variability)

this is the time b/t heart beats and is a measurement of the variation in R to R intervals on ECG

increases

the effect of chronic exercise on HRV

decreases as exercise intensity increases and SNS takes over

during an acute bout of exercise, how is HRV affected

HRV

this measure may be useful to monitor physical and emotional stress, sleep performance, predict recovery following exercise, and/or readiness to train

increase preload/EDV, increase contractility, decrease afterload (aortic BP)

three influences on SV

preload/EDV

volume of blood in the ventricles at the end of diastole and is associated with the Frank-Starling Relationship

afterload/aortic BP/vascular resistance

pressure the heart must pump against to eject blood

contractility

strength of the ventricular contraction

40-60%

the percentage of VO2max in which SV plateaus during exercise

increase venous return, venoconstriction, skeletal muscle pump, respiratory pump

influences on preload

respiratory pump

this is associated with increased RR and is a major determinate of venous return with upright posture

Frank-Starling relationship

this principle states a greater preload/EDV results in a larger contraction d/t increased stretch in the heart causing a greater recoil

inversely

SV and afterload are __________ related

afterload increases during exercise but there is a decrease in peripheral resistance which causes an overall decrease in afterload d/t decreased total peripheral resistance

describe the effect of an acute bout of exercise has on afterload

nitrates

this group of medications are given for angina, HTN (acute crisis or chronic), and HF and reduce afterload or preload or both

contractility

positive inotropic state

direct SNS stimulation of heart via increased levels of catecholamines (E/NE)

how is contractility enhanced during an acute bout of exercise

decreases HR and contractility

effects of beta blockers on HR and contractility

increases contractility

effect of inotropic agents on contractility

CO

the Fick principle helps estimate which value

VO2/(a-vO2 difference) = CO

the Fick equation

a-vO2 difference

this is the difference in oxygen on arteriole vs venous side (requires a blood test)

increase max SV and decrease max HR; overall increase in CO

effects of chronic training on CO, SV, and HR

~93 mmHg; because individual spends more time in diastole so therefore it has a bigger influence on MAP

why is MAP closer to diastole during rest

increases in UE > LE

what happens to BP during aerobic exercise

increases in LE > UE

what happens to BP during anaerobic exercise

d/t to increased time spent in systole causing an upward drift in MAP

resting MAP is 93 mmHg and activity MAP is 100 mmHg which is closer to the arithmetic mean; describe why activity MAP is closer to the mean

pulse pressure

this measure is an index of arterial stiffness in older adults and high values (>60 mmHg) are associated with atherosclerosis and fluid overload; low values (<40 mmHg) are associated with low resistance and low blood volume (blood loss)

> 60 mmHg

a pulse pressure greater than this number may be a predictor of CV disease in adults over 60

CO increases

blood is redistributed to exercising muscle (vasodilation) and maintained or reduced to other tissues (vasoconstriction) (d/t ANS and local chemical factors)

core body temp rises and blood is diverted to the skin

fluid lost in sweat and respirations

endocrine changes

5 factors that affect BP during an acute bout of exercise

increase; decrease

__________ in CO > _________ in TSPR so MAP is maintained

increased CO is offset in LE by dilation of large vascular beds that are not found in the UE

explain why UE BP increases more than LE BP during aerobic exercise

BP falls below pre-exercise levels for up to 12 hrs

acute adaptation in BP as a result of submaximal exercise

gradual decrease in SV d/t dehydration and reduced plasma volume and gradual increase in HR (cardiovascular drift)

changes in HR and SV to maintain CO during prolonged exercise

cardiovascular drift

this occurs during prolonged exercise and is characterized by HR slowly increasing as SV decreases proportionately to maintain CO

HR max increases and SV decreases

effects of detraining on HR and SV