Module 4 Flashcards
What is the formula for cardiac output and its definition
Cardiac output: the amount of blood volume pumped by the heart in one minute
Q = SV x HR
What is the anatomy of the heart? Draw out
What is the right side of the heart do?
Receives blood returning from elsewhere in the body. Pumps blood to the lungs through a pulmonary circulation
What does the left side of the heart do?
Receives oxygen rich blood from the lungs. Pumps oxygenated blood to the rest of the body
Define artery
Artery: high-pressure tubing that propels oxygen rich blood to tissues. comprised of layers of connective tissue and smooth muscle
Why does no gas exchange occur between arterial blood and surrounding tissues?
Because the walls of the arteries are too thick
Define precapillary sphincter
Precapillary sphincter: a ring of smooth muscle that encircles the capillary at its origin and controls its diameter
Describe the constriction and relaxation of the sphincter
Constriction and relaxation provide a means for blood flow regulation to meet metabolic requirements. One in 30 capillaries are open in the muscle at rest
What two factors trigger precapillary sphincter relaxation (dilation)
- Driving force of increased local BP (plus intrinsic neural control)
- Local metabolites produced in exercise (lactate, Pyruvate, ketones, glycerol etc)
What happens to the flow resistance when the radius of a vessel decreases by half
Increases by 16
Describe veins
Veins are not as muscular as arteries, and prevent backflow. Eventually reach the vena cava to empty into the right atrium.
What is the largest vein in the body
Inferior vena cava
Describe the three different blood pressures
- Systolic blood pressure. Blood pressure during left ventricular contraction. Estimates the work of the heart against of arterial walls
- Diastolic blood pressure. Blood pressure during cardiac relaxation or diastole. With high peripheral resistance pressure will remain high for longer
- Mean arterial pressure. Slightly lower than the actual average pressure, accounts for the fact that the heart remains in relaxation for longer
What is the formula for mean arterial pressure
Map = diastolic BP + [(systolic minus diastolic BP) / three]
What factors affect mean arterial pressure
Increased muscle force cardiac output or vasoconstriction (diameter) all increase mean arterial pressure

What happens to blood pressure during exercise
Systolic BP will have a sharp increase followed by slight increase
Diastolic BP it will remain very level with minor decreases
Describe the normal route for impulse transmission within the myocardium
- The impulse will originate from the Sino atrial node located in the right atrium, and spread across the atria contract them
- The impulse then passes to the AV node travels along the atrioventricular bundle into the right and left cruise, spreads into the ventricles and contracts them
- Dissipation of the impulse will cause the atria and ventricles to relax
Describe the ECG Waze and it’s different components
- Atrial depolarization - P-wave: depolarization of the atria before atria contract
- Ventricular depolarization – QRS wave: signals electrical changes from ventricular depolarization before ventricles contract
- Ventricular repolarization – T wave: represents ventricular repolarization that occurs during ventricular diastole
What portion of the normal ECG would tell us our heart rate
The peak of the R-wave
What can be an a indication of a past heart attack or even a current one
B-flat portion between the QRS wave and the T-wave, if depressed or increase, indicates a history of heart attack or even a current one
What is the distribution of sympathetic and parasympathetic nerve fibres with the heart
- parasympathetic nerve endings concentrate in the atria including the SA and AV nodes
-  sympathetic nerve fibres supply the SA and AV nodes, plus the muscle of the atria and ventricles
What causes the release of epinephrine and norepinephrine, and what kind of effects do they have on the heart
Stimulation of sympathetic cardio accelerated nerves release epinephrine (vasoconstriction except for coronary arteries and chronotropic: increase heart rate) and norepinephrine (Inotropic: increases contractility)
Define Adrenergic
Relating to or denoting nerve cells in which Epinephrine, norepinephrine or noradrenalin acts as a neurotransmitter
How does sympathetic ns influence dilation?
Dilation of blood vessels under decreased adrenergic (sympathetic) influence
Symp activity typically causes constriction, but it can balance with parasympathetic so that it shunts towards active muscles
What do you the sympathetic and parasympathetic divisions do to the heart/body
Heart: parasympathetic decreases heart rate, sympathetic increases heart rate and contraction
Body: parasympathetic relaxes muscles, sympathetic contracts muscles
How does the parasympathetic division decrease heart rate
- Neurons release acetylcholine which delays sinoatrial discharge, which slows heart rate
- at the beginning of low exercise heart rate increases largely due to the inhibition of parasympathetic stimulation, without any additional sympathetic drive
What is the cause of bradycardia
Results from stimulation of the vagus nerve from the medulla cardio inhibitory centre
Describe the innervation of parasympathetic and sympathetic division when in strenuous exercise
Additional parasympathetic inhibition and direct activation of sympathetic cardio acceleratory nerves
When measuring arterial oxygen saturation would it matter if you sampled blood from the arteries supply in active vs inactive muscle?
No! Oxygenation of blood happens at the lungs and does not happen at the arteries. It would matter if you’re measuring venous carbon dioxide saturation. If you measure the saturation of the veins in active vs inactive muscle it will have very different values.
How would the heart behave without chemical or neural inputs?
The heart will have a resting heart rate of a roughly 100 bpm. If we kill the sino atrial node, it would still beat but would be much slower. Without chemical or neural inputs the heart rate will not change
Why does blood pressure increase during exercise? How?
We vasodilate to allow for more blood flow. when the heart is relaxed, it means that our diastolic blood pressure does not change by much. When we exercise, our cardiac output goes up to allow more oxygen to get to the muscle.
Explain how each branch of the autonomic nervous system can increase heart rate
Sympathetic increases heart rate and contraction
Parasympathetic Decreases heart rate
 What are some of the neural mechanisms for cardiovascular regulation?
- To the higher brain
- aortic and carotid arterial mechano receptors (arterial baroreflexes)
- cardiac mechano-ceptors (cardio pulmonary reflexes)
- Skeletal muscle (exercise precursor reflex) - efferent
- Heart chronotropic or inotropic function
- Active or inactive Skeletal muscle contraction
- kidney and splenic bed vasoconstriction
 What are some of the neural mechanisms for cardiovascular regulation?
- To the higher brain
- aortic and carotid arterial McCann over receptors (arterial baroreflexes)
- cardiac mechano-ceptors (cardio pulmonary reflexes)
- Skeletal muscle (exercise precursor reflex) - efferent
- Heart chronotropic or inotropic function
- Active or inactive Skeletal muscle contraction
- kidney and splenic bed vasoconstriction
What provides the greatest control over heart rate during exercise
Central command
How does the heart rapidly turn on during exercise
Turns on rapidly by decreasing parasympathetic inhibitory input, and increasing stimulation from central command
What is the possible reason for explaining how emotional states can affect cardiovascular responses
central command! Impulses from the higher brain centre can continually modulate medullary activity and alter the hearts activity
What are the three mechanisms for peripheral input
- Afferent info - Reflex neural input - information from type three afferents sent information regarding mechanical deformation (changes in pressure, touch etc)
- Chemical stimulation - “exercise precursor reflex” epinephrine, norepinephrine etc
- Feedforward outflow - motor areas’ feedforward info sent and recieved
What kind of mechano-ceptors govern central nervous system’s regulation of the heart?
- Baroceptors in carotid sinus and aortic arch
“ baroceptor reflex” refers to the sending of information from the receptor to the medulla and back to the heart to adjust rate
What kind of feedback is used for baroreceptors in the heart and medulla
Negative feedback
What three factors determine resistance of blood?
- Blood thickness
- Length of conducting tube
- Blood vessel radius
What happens the distribution of blood before and after exercise
With increasing intensity there is less blood going to the kidney liver and G.I. tract
more blood going to the muscle skin and heart
Any __________ in energy expenditure requires __________ Adjustment in blood flow that impacts the cardiovascular system
Increase. Rapid
How do local arterials of active muscles react to exercise
Local arterials of active muscles dilate
How do vessels to tissues react to exercise
Tissues that can temporarily compromise their blood supply constrict
What allows blood flow to non-active tissues be reduced during exercise
- Increased sympathetic nervous system outflow
- Local chemicals that directly stimulates vasoconstriction or enhance effects of other vasoconstrictors
What does the opening of dormant capillaries in exercise result in
- Increases total muscle blood flow
- Delivers a large blood volume with minimal increase in blood flow velocity
- Increases effective surface area for gas and nutrient exchange
How does nitric oxide regulate tissue blood flow
Nitric oxide serves as a signal molecule that dilate blood vessels and decreases resistance
Synthesis of nitric oxide is provoked by shearing stress and vessel stretch
Released by the vascular endothelium
Give some examples of the integrative responses during physical activity
- Neural command centre above the medulla initiates cardiovascular changes before and during movement
- heart rate and contractility increase from feedforward input from cardiovascular center, decreasing parasympathetic activation
- Predictable changes in regional blood flow occur in proportion to exercise intensity
- Population of dilation or construction optimizes blood flow for needed areas while maintaining blood pressure
- metabolites act directly to dilate vessels
- vasodilation reduces peripheral resistance
Describe what Happens to heart transplant patients
- after receiving the healthy heart, they have the same cardiac output with a much lower heart rate
- Because they lose some sympathetic innervation it has high of a peak as they did before the transplant
- no stroke volume plateau during graded exercise! instead, it progressively increases
- Post transplant, the heart cannot accelerate as quickly during strenuous effort
What is the average cardiac output at rest for men and women
Men: 5 L per minute. Average heart rate = 60 bpm, average stroke volume = 75 mL
Women: 4 L per minute. Average heart rate = 65 bpm, average stroke volume = 60 mL
What is the direct fick method
Direct fick method: expresses relationships between V02 and arteriovenous difference to determine the cardiac output
Cardiac output = VO2 divided by arteriovenous difference
What method of measuring cardiac output requires invasive methodology?
The direct fick method
How does cardiac output Different for untrained and trained individuals?
Untrained: cardiac output = 5 L per minute, resting heart rate = 70 bpm, stroke volume = 71 mL
Trains: Cardiac output = 5 L per minute, resting heart rate = 50 bpm, stroke volume = 100 mL
What are some factors that might explain large stroke volume and low heart rate of endurance trained athletes
- Increased vagal tone and decreased sympathetic Drive, both of which slow the heart
- Increased blood volume, myocardial contractility, and compliance of the left ventricle, all of which augment the heart stroke volume
What is the relationship between the systemic blood flow and intensity of physical activity
Blood flow increases directly with intensity of exercise. Cardiac output increases rapidly during the transition from rest to steady state exercise, and then rises gradually until it plateaus when blood flow meets the exercise metabolic requirements
What is the main contributor to a maximal cardiac output
Stroke
What is the average cardiac output for untrained versus trained individuals during maximal activity?
Untrained: 22 L per minute, heart rate = 185 bpm, stroke volume = 113 mL per beat
Train: 35 L per minute, heart rate = 195 bpm, stroke volume = 179 mL per beat
What are the maximum values for cardiac output for men with low normal and high V02 max values
Low [mitral stenosis], VO2 max = 1.6 L per minute, cardiac output = 9.5 L per minute
 normal [sedentary], VO2 max = 3.2 L per minute, cardiac output = 20 L per minute
Hi [athlete], V02 max = 5.2 L per minute, cardiac output = 30.4 L per minute
What is the formula for stroke volume
Stroke volume = end diastolic volume minus and systolic volume
What mechanisms increase stroke volume during exercise?
- Enhanced cardiac filling and diastole, followed by a more forceful systolic contraction
- Normal ventricular filling with subsequent more forceful ejection and emptying during systole
3. Training adaptations that expand blood volume and reduce resistance to blood flow in peripheral tissues
What factors cause greater preload during the diastole
Any factor that increases venous return or slows the heart rate. An Example is the stretch of myocardial fibres to increase end diastolic volume and initiate a more powerful ejection stroke.
Define frank starling law
Frank starling law: contraction force of cardiac muscle remains proportional to its initial resting length
What are the three main ideas behind the frank starling law
- Relates to the length-tension relationship of muscle
- as the length of muscle fibres increase the resulting force with their contraction will be greater
-  increased pre-load = increased contractility = increased stroke volume
What might result in greater systolic emptying
Catecholamine release exercise enhances myocardial contractile force to facilitate greater systolic emptying
** enhanced systolic ejection occurs because ventricles always contain a functional residual blood volume
Why does enhanced systolic ejection occur despite increased resistance of blood flow
Because vessels have residual blood volume
because there are many other mechanisms in place to increase ESV without increasing BF (inotropic effect)
At rest what percentage of oxygen in the blood does the myocardium use
75% flowing through the coronary circulation
What happens to blood flow and oxygen consumption of coronary circulation and cerebral blood during exercise
Coronary circulation has a 4 to 5 fold increase in blood flow
 Cerebral blood flow increases during exercise by 25 to 30%
At rest how much oxygen has carried in arterial blood, cardiac output and V02?
arterial blood carries 200 mL of oxygen per litre
Cardiac output = 5 L, therefore 1000 mL of O2 is available to the body
VO 2 = 250 to 300 mL per minute, allowing 750 mL of oxygen to return unused to the heart
What is referred to as oxygen in reserve
Oxygen in reserve represents the extra oxygen circulating above resting requirement
Describe the association between maximal cardiac output and VO2 max
- Low VO2 max = low max cardiac output
- A 1 L increase in VO2 Max = 5 to 6 L increase in blood flow (unchanged regardless of exercise intensity)
- High V02 max and Max cardiac output for distinguishing characteristics of preadolescent athletes
- with endurance training , increases in Max cardiac output = increases in VO2 Max
By how much do women and men’s cardiac outputs differ?
Women exercise at sub max VO2 with 5-10% larger Q (due to 10% lower Hb concentration)
In children, describe how sub maximal exercise affects their cardio response
In children, their hearts are not as developed, so they have higher heart rates to compensate for lower stroke volume, along with slightly higher a-vo2 diff
Describe the relationship between cardiac output and oxygen consumption for sedentary vs athletes
- all of the lines line up and are pretty linear, but end at their vo2 max, which are all different
Describe the relationship between stroke volume and oxygen consumption for sedentary vs athletes
- higher at rest in trained vs sedentary
- at moderate intensity, it increases. We don’t always have our max stroke volume
- once we hit the plateau in stroke volume, the only way to increase our cardiac output is with an increase in heart rate
What happens to the graph of heart rate and oxygen consumption with training?
shifts the graph down and right
How does a-vo2 differ by training
- not much of a difference.
- peak a-vo2 does not increase much with training
- we CAN get better at taking a higher percentage of the blood away from muscles , and increase Hb count
What is the average a-vo2 at rest?
5ml O2/dL of blood
(15mL = 75% of original O2 content still remains bound to hemoglobin)
How do arterial and venous blood O2 content vary at rest/exercise
Arterial = 20mL/dL, kinda stays here through exercise
Venous = 12-15mL/dL during rest, 2-4 mL/dL during max exercise
- as mitochondria increases ATP production, partial pressure of oxygen decreases and our a-vo2 diff increases just a little
What factors affect a-vo2 during exercise
- central/peripheral factors interact to increase oxygen extraction. (Blood diverts to active muscle, some tissues decrease blood supply, training redirects bigger portions of blood to active muscle)
What is the equation for the Karnoven method?
HR reserve = HR max - HR rest
HR @ % of VO2 max = (HR reserve x % of VO2 max) + HR Rest
How does arm vo2 differ from the legs?
Arm vo2 is 20-30% lower than the legs. Differences are related to smaller muscle mass activated in arm exercise, along with it produces lower max values for hr and ventilation.
Oxygen consumption of the arms - what are the two factors that affect its consumption?
- Lower mechanical efficiency from added cost of nearby muscles
- Recruitment of additional musculature to stabilize the torso
What is higher in arm exercises vs leg
Hr, bp, pulmonary ventilation, effort
What is the reason for elevated heart rate during arm exercise
- Greater feed forward stimulation from the brains central command
- Increased feedback stimulation to the medulla from peripheral receptors in active muscle
What do arm exercises produce more of compared to legs?
Greater metabolic and physiological strain
