HK 368- Exam II
Which of the following would be considered an excellent VO2 maximum for a college-aged man? A) >60 ml/kg/min B) 50 ml/kg/min C) 30 ml/kg/min D) 20 ml/kg/min
A) >60 ml/kg/min
Increasing end diastolic volume would result in an increase in: (1 point) A) preload B) end systolic volume C) a-vO2 difference D) arterial oxygen content
A) preload
While exercising in a hot, dry environment the predominate means of cooling the body is (assume no influence of clothing or wind velocity)? A) sweating B) radiation C) convection D) evaporation
A) sweating
Stroke volume can increase with dynamic exercise due to an: A) increase in sympathetic stimulation B) increased end-diastolic volume C) metabolic vasoconstriction in skeletal muscle D) decreased venous return
B) increased end-diastolic volume
formula for MAP
MAP=DBP + 1/3 ( SBP-DSP ) or MAP = CO x TPR
What are the three variables used to calculate oxygen consumption?
Stroke volume, heart rate, and arteriovenous difference
fick equation
VO2 = CO x a-vO2 difference
factors that influence afterload
anything that opposes ventricular ejection 1. peripheral resistance (primary factor during exercise) 2. viscosity of blood 3. valve dysfunction
PNS
dominant at rest, more stimulation= lower heart rate, less stimulation= higher HR. innervates SA and AV nodes
SNS
dominate during exercise and stress, more stimulation= higher HR, less stim= lower HR. innervates nodal tissue and contractile tissue
blood flows
down a pressure gradient- high to low normal systolic Bp = 120 mmHg
effect of a larger pressure difference
increased blood flow
veins
low pressure system and deoxygenated blood
glucagon
the hormone of "starvation" and promotes the mobilization of these fuels when nutrient supply is low
blood flow to skin during high intensity exercise
vasoconstriction, to conserve CO
blood flow to skin during moderate intensity exercise
vasodilation, cooling response
preload dictates
ventricular filling pressure
preload can be influenced by...
ventricular filling time, ventricular compliance, atrial systole
preload
volume of blood in chamber before contraction
end diastolic volume
volume of blood in each ventricle at end of diastole- filling phase
end systolic volume
volume of blood remaining in each ventricle after systole- contraction phase
if resistance increases, what happens to ΔP in order to maintain blood flow?
ΔP must increase
what cells secrete insulin?
β cells
what does vasodilation of skeletal muscle cause?
decreased TPR
effect of increased resistance on Q
decreased blood flow
how do we get more blood flow to working muscles?
1. increase cardiac output 2. shunt blood flow, send more to working muscles 3. decrease TPR 4. vasodilation in working muscle
breakdown of a triglyceride results in...
1 glycerol and 3 FFA's
3 ways stretching of cardiac muscle results in greater tension
1. creates optimal actin/myosin overlap 2. myocites become more sensitive to calcium 3. opening of stretch-activated Ca channels
cardiac output
= blood flow =how much blood is being delivered to muscles
Increasing calcium levels in the cardiac myocytes is the primary mechanism for: A) Increasing contractility B) Increasing heart rate C) Decreasing TPR D) Increasing preload
A) Increasing contractility
VO2max is greater in aerobically trained individuals primarily due to an increase in: A) maximum heart rate B) a-vO2 difference C) end systolic volume D) stroke volume
A) maximum heart rate
Deoxygenated blood from the veins first reaches the ______________ before being transported to the lungs. A) Left Atrium B) Right Atrium C) Left Ventricle D) Right Ventricle
B) Right Atrium
Which of the following would likely increase during acute exercise? A) Venous oxygen content B) a-vO2 difference C) Arterial oxygen content D) Liver blood flow
B) a-vO2 difference
An increase in which of the following could increase left ventricular stroke volume? A) contractility B) afterload C) ESV D) parasympathetic stimulation
B) afterload
Factors contributing to an increase in stroke volume with exercise include: A) increased EDV, decreased ejection fraction, and increased SNS stimulation. B) increased venous return, increased plasma epinephrine, and increased contractility. C) decreased venous return, increased PNS activity, and increased ESV. D) increased preload, increased SNS stimulation, and increased EDV.
B) increased venous return, increased plasma epinephrine, and increased contractility.
In an unacclimated individual, which of the following would be greater at any given exercise intensity when exercising in a hot environment compared to exercising in a cooler environment? A) Central blood volume B) Stroke volume C) Heart rate D) Muscle glycogen content
C) Heart rate
Which of the following would impair/reduce the ability to cool the body during exercise? A) Water ingestion B) Exercising in your underwear C) High relative humidity D) Cloudy day
C) High relative humidity
Why does exercising in a full football uniform result in greater rise in core temperature during exercise? A) Enhances convection B) Reduces skin blood flow C) Limits evaporation of sweat D) Prevents sweat loss
C) Limits evaporation of sweat
Trained individuals have a greater capacity for heat dissipation because of: A) increased skin blood flow B) decreased sweat rate C) increased VO2max D) decreased blood volume
C) increased VO2max
Heat acclimatization improves heat dissipation by: A) increasing heart rate during exercise B) decreasing VO2 max C) increasing sweat production D) decreasing skin blood flow
C) increasing sweat production
formula for cardiac output
CO = HR x SV
Which of the following would result in an increase in ejection fraction A) Increased afterload B) Decreased preload C) Increased venous return D) Increased contractility
D) Increased contractility
What is one reason why excessive sweating could result in a reduction in exercise performance? A) Lower heart rate B) Lower plasma volume C) Increased skin blood flow D) Increased plasma sodium
D) Increased plasma sodium
Which of the following does not increase with increasing exercise intensity? A) Heart rate B) Stroke volume C) SNS stimulation D) PNS stimulation
D) PNS stimulation
Which adaptation aids the trained athlete in reaching a higher preload in the left ventricle and, thus enhanced exercise performance? A) Increased skeletal muscle capillary density B) Reduced sympathetic stimulation C) Increased parasympathetic stimulation D) Plasma volume expansion
D) Plasma volume expansion
1. Measurement of carbon dioxide production and calculations of ____________ help determine the contributions of fat and carbohydrate to the energy expenditure of the activity. A) Heart Rate B) Stroke Volume C) Minute Ventilation D) Respiratory Exchange Ratio
D) Respiratory Exchange Ratio
Using a fan during exercise will promote body cooling by facilitating: A) evaporation and convection B) convection and conduction C) radiation and evaporation D) conduction and evaporation
D) conduction and evaporation
During dynamic exercise, blood flow increases specifically to active skeletal muscle largely as a result of: A) an increase of sympathetic vasoconstrictor nerve activity. B) shunting of blood to the liver. C) an increase in parasympathetic nerve activity. D) local production of vasodilator metabolites.
D) local production of vasodilator metabolites.
During dynamic exercise, e.g. running, diastolic blood pressure often remains stable or decreases. Which of the following physiological changes that occur with exercise could account for the effect of exercise on diastolic blood pressure? A) an increase in contractility. B) a decrease in total peripheral resistance. C) an increase in preload. D) the shunting of blood to the skin.
D) the shunting of blood to the skin.
formula for ejection fraction
EF = ( SV / EDV ) *100
Insulin's effect on Liver
Higher storage of glucose Higher glycogen synthesis Lower gluconeogenesis Promotes conversion of glucose to fat
Insulin's effect on Skeletal Muscle
Principle site of glucose disposal Increased glucose uptake Higher glycogen synthesis Higher glucose breakdown and oxidation, which promotes formation of triglycerides Higher protein synthesis Lower protein degradation
path of blood flow
Right atrium→ right ventricle → contraction → lungs → left atrium → left ventricle → contraction → aorta → tissues
stroke volume formula
SV = EDV - ESV
afterload
The pressure the ventricle must generate to eject blood.
insulin
When nutrients are in excess, insulin stores the excess as fuel.
a-vO2 difference
a- arterial O2 content v- venous O2 content difference- how much O2 was extracted from the arterial blood
what cells secrete glucagon?
alpha cells
pressure gradient
blood flows from high to low pressure
oxygen extraction during exercise
can increase three fold, decreased venous oxygen, greater a-vO2 difference
systole
contraction phase
low CHO diet
dec muscle glycogen stores and dec aerobic exercise time to exhaustion
relationship between blood flow, pressure, and resistance
flow is directly proportional to blood pressure gradient and inversely proportional to resistance Q (blood flow) = ΔP (change in pressure) / R
Glucogeonesis
glycogen (stored glucose) --> glucose
starling's law
greater stretch of the cardiac muscle results in greater force of contraction
arteries
high pressure system and oxygenated blood
effects of static exercise on SV
impedes venous return--> lower SV
effects of dynamic exercise on BP
inc SBP, DBP may dec due to dec vascular resistance, little to mod increase in MAP
effects of static exercise on BP
inc TPR --> dec flow, SBP and DBP inc, MAP inc due to DBP inc
how does glucagon work to increase blood sugar levels
inc gluconeogenesis to raise blood glucose levels
high CHO diet
inc muscle glycogen stores and inc aerobic exercise time to exhaustion
effects of CHO consumption during aerobic exercise
inc time to fatigue and maintains power output during prolonged exercise
preload increase
increased venous return = increased EDV = increased tension = increased force of contraction
effects of static exercise on CO
increases due to increased HR
order of carbohydrate supply for active muscles from largest to smallest
muscle glycogen > liver glycogen > plasma glucose
Islets of Langerhans
pancreatic cells that secrete glucagon and insulin
primary energy sources during long term (~4 hr) exercise, after muscle glycogen has depleted
plasma FFA's and adipose tissue triglycerides
three things that contribute to SV
preload, afterload, contractility
glucagon action on the liver
promotes synthesis of glucose promotes gluconeogenesis promotes glycogen breakdown and inhibits synthesis enhances glucose release
diastole
relaxation phase
which side of the heart is smaller and why
right side is smaller- less muscle since there is lower pressure because the pulmonary circuit is smaller than systemic.
how does insulin work to lower blood sugar
stores glucose as glycogen to lower glucose content in blood
effect of length-tension relationship on cardiac muscle
stretching of cardiac muscle gives optimal actin/myosin overlap and increases passive tension. both contribute to greater force production
