Chapter 6 Shit Flashcards
What is cardiac output (Q)?
-amount of blood pumped by the heart in liters per minute.
-stroke volume x heart rate
-Increases rapidly during initial aerobic activity
-Followed by a gradual increase and plateau
-Resting level = 5L/min
-Can increase to a maximum of 20-22L/minute
How does stroke volume change during aerobic exercise or exercise in general?
-Rises during the onset of exercise
-Plateaus once oxygen uptake reaches 40-50% maximum
-Untrained stroke volume of college men - 100-120ml blood/beat
-Trained men = up to 150-160ml per beat
-Women = 25% less than men
-End=diastolic volume and catecholamine action determine stroke volume
How is venous return increased during exercise?
-Vasoconstriction (from sympathetic activation)
-Increased skeletal muscle pump
-Increased respiratory frequency and tidal volume
-Increased venous return results in more forceful heart contractions via the Frank-starling mechanism
What is Frank-starling mechanism?
-Increased end-diastolic volume stretches myocardial fibers resulting in more forceful contraction and increased systolic ejection
-Increased cardiac ejection characterized by increased ejection fraction - the fraction of the end-diastolic volume that is ejected during heart contraction
How is heart rate effected by aerobic exercise?
-Increased immediately before and at the beginning of exercise
-HR increases linearly with exercise intensity
-Increases during acute bout of aerobic exercise
-Proportional to the mass of muscle used
What is maximal oxygen uptake?
- greatest amount of O2 usable at the cellular level
-Correlates with degree of physical conditioning
-Related to heart and circulatory system’s ability to transport O2 and body tissue’s ability to use it
-Resting O2 uptake estimated - 3.5mL O2/kg bodyweight per minute - defined as one metabolic equivalent (MET)
-Normal VO2 max = 25-80ml/kg/minute
-Fick equation is used to determine oxygen uptake/beat
What is the fick equation?
- VO2=Qxa-VO2 difference
- a-VO2 = Arteriovenous difference - the difference in O2 content of arterial and venous blood
EXAMPLE- I.E. HR=72bpm, stroke volume = 65ml blood, a-VO2=6, weight = 80kg
VO2= 281mlO2/min/80KG
VO2=3.5 mlkg
What happens to blood pressure with aerobic exercise?
-Systolic blood pressure = pressure during contraction
-Combined with HR to estimate oxygen consumption of the heart
-Rate-pressure product = heart rate x systolic blood pressure
-Diastolic blood pressure = BP exerted on arterial walls when no blood being ejected
-Typical resting BP = 120 mmHg/80mmHg
-Maximal exercise can raise BP to 220-260mmHg/90mmHgdiastolic
-Mean arterial pressure - average pressure throughout cardiac cycle
-Typically, lower than average of systolic and diastolic
-MAP = ((systolic - diastolic)/3) + diastolic
What happens to the control of local circulation for aerobic exercise?
-Vasoconstriction and vasodilation are the primary mechanisms regulating blood flow
-Blood flow to active muscles increased via local dilation of arteries
-Restricted in other areas by constriction of arterioles
-At rest 15-20% of cardiac output to muscles
-During work up to 90% of cardiac output to muscles
What happens to the ventilation of your body during aerobic exercise?
-During exercise breathing increases from 12-15 breaths to 35-45 breaths per minute
-Tidal volume (volume of air inhaled and exhaled with each breath) increases from between .4 and 1.0 L to upwards of 3L or greater
-Low-moderate exercise increases O2 uptake and CO2 removal in proportion to increased ventilation
What is the ventilatory equivalent?
-ration of minute ventilation to oxygen uptake
-Ranges from 20-25 L of air/liter of O2 consumed
-Intense exercise increases the role of breathing frequency
-Minute ventilation rises disproportionately to oxygen uptake
-Parallels the rise in blood lactate
-Upwards of 35-40 L of air per liter of O2 during intense exercise
What is the alveoli?
- functional unit of pulmonary system where gas exchange occurs
What is anatomical dead space in the lungs?
- the area not functional for gas exchange (trachea, nose, mouth)
-150 mL in young adults
-Increases with age
-Area increases during deep breathing due to stretching of passages
-Increases similar to tidal volume during deep breathing
-Tidal volume increases more than anatomical dead space
What is physiological dead space in the lungs?
-Alveoli with poor blood flow, ventilation, or other problems
-Lung diseases can increase physiological dead space
What are the overall effects of aerobic exercise on the lungs?
-Larger amounts of O2 diffusion from capillaries to tissues
-Increased CO2 from blood to alveoli
-Increased minute ventilation to maintain gas concentrations
What are the gas responses to aerobic exercise?
Increased diffusion of O2 and CO2 due to decrease in partial pressure of O2 (40mmHg - 3,,Jg) in interstitial fluid and increase in CO2 (46mmHg - 90mmHg) partial pressure
What are the mechanisms of blood transport of gasses and metabolic by-product?
Oxygen and Carbon dioxide
How is oxygen involved in blood transport of gasses and metabolic by-product?
-Either dissolved in plasma or carried by hemoglobin
-Low fluid solubility of oxygen - less than 3ml oxygen per liter of plasma
Most oxygen is carried in hemoglobin
-15-16g hemoglobin per 100mL blood in men
-14g hemoglobin/100mL blood in women
-One gram of hemoglobin can carry 1.34mL of oxygen
-Oxygen capacity of 100mL blood around 20mL in men and slightly less in women
How is Carbon dioxide involved in blood transport of gasses and metabolic by-product?
-Removal more complex than oxygen delivery
-Diffuses across cell and then transported to lungs
-Around 5% of metabolic CO2 in plasma
-Some CO2 via hemoglobin (small amount)
-Some CO2 removed via bicarbonate (HCO3+)
-Reversible reaction
+Formation of carbonic acid with the water in red blood cells
+Sped up by carbonic anhydrase
+Acid broken into H+ and bicarbonate
+H+ combines with hemoglobin due to its buffering properties
+Maintains blood ph
+Bicarbonate diffuses to plasma while chloride diffuses into red blood cells
-Lactic acid begins to accumulate when O2 availability cannot meet exercise demands
What are the chronic cardiovascular adaptations to aerobic exercise?
-Increased maximal cardiac output
-Increased stroke volume
-Reduced resting and submaximal exercise heart rate
-Increase capillary density in muscle fibers
+Function of volume and intensity of training
+Decreases diffusion distance for oxygen and metabolic substrates
Why is increased maximal oxygen uptake crucial for aerobic performance?
-Enhanced cardiac output results in lowering discharge rate due to increased stroke volume
-Slow resting heart rate (bradycardia) seen in highly conditioned athletes (40-60bpm)
-Slow HR rise in response to standardized submaximal efforts a hallmark of aerobic endurance training
-Over 6-12 months of aerobic training results in large increase in cardiac output
-Increased left ventricle chamber volume and wall thickness increases stroke volume
What are Respiratory adaptations to aerobic training?
-Increased tidal volume with maximal exercise
-Increased breathing frequency with maximal exercise
-Reduced tidal volume and breath frequency at submaximal exercise
-Adaptations largely occur in the specific muscles being trained
What are neural adaptations to aerobic training?
-Increased efficiency
-Delayed fatigue in contractile mechanisms
-Rotations of neural activity between synergists and motor units within the muscle
-More efficient locomotion and lower energy expenditure
What are muscular adaptations to aerobic training?
-Increase in glycogen-sparing (decreased glycogen use)
-Increased fat-utilization within the muscle
+Raises the intensity at which OBLA occurs - up to 80-90% aerobic capacity
-Increased oxidative capacity of type 2a fibers
+Reduced glycolytic enzymes and some size reduction will occur
+Conversion of type 2x to type 2a fibers
+No evidence of type 2 to type 1 transitions
-Some limited hypertrophy of type 1 muscle fibers
-Increased mitochondrial density
+Mitochondria produce ATP from oxidation of glycogen and free fatty acids
+In combination with increased O2 availability more mitochondria increase the oxidative capacity of muscle tissue
-Increased myoglobin content - a protein that transports oxygen within the muscle cell
-Increased activity of the enzymes involved in aerobic metabolism
-Increase in glycogen and triglyceride stores