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Kine 433 Exam 1 - Woodman
Terms in this set (251)
What are the two circuits of the CV system?
1. Pulmonary circuit
2. Systemic circuit
What are the two features of the pulmonary circuit?
1. Low pressure
2. Provides BF to lungs
What are the two features of the systemic circuit?
1. High pressure
2. Provides BF to all other tissues
What is the macrocirculation?
Arteries and veins
What is the microcirculation?
Arterioles, capillaries, and veins
What does the macrocirculation do?
Provides BF to and from tissues
What does the microcirculation do?
Regulates BF, BP, and exchange of O2, CO2, and nutrients
What are the 3 CV adjustments to exercise?
1. Increase CO
2. Redistribute CO
3. Increase venous return
What is CO at rest?
What is CO when active?
What are the 4 adaptations of the heart?
2. Fatigue resistant
What is the SA node?
What is the AV node?
Delays AP to allow ventricles to fill
What are the bundle branches?
Transmit electrical signals to ventricles
What are the Purkinje fibers?
Rapid conduction so ventricles contract as a unit
What is the primary function of the heart?
Act as a pump
_____ arteries provide BF to myocytes.
What are capillaries?
Dense network to aid O2 exchange
What is mitochondria?
Rich supply provides ATP to constantly active muscles
The heart is innervated by the _____.
What things make the heart spontaneous and rhythmic?
SA node, AV node, bundle branches, Purkinje fibers
What things make the heart fatigue resistant and regulatable?
Arteries, capillaries, mitochondria, and nerves
_____ innervates SA and AV nodes.
What does the PNS do in the heart?
Releases ACh to decrease HR and conduction velocity
_____ innervates SA node, AV node, and LV.
What does the SNS do in the heart?
Releases NE to increase HR and SV.
What is the intrinsic heart rate?
What are the 3 layers (tunics) of blood vessels?
What is the tunica intima?
Single layer of endothelial cells; it is in direct contact with the blood
What is the tunica media?
Primarily smooth muscle cells; contracts and relaxes to regulate BF and BP
What is the tunica adventitia?
Primarily collagen; anchors the vessel
What is the primary function of arteries?
BF from the heart to tissues
What are the adaptations of arteries?
Thick walls to withstand high pressure, large lumens to provide low resistance to BF, thick walls to prevent gas exchange, elastic fibers to propel blood forward
What is the primary function of arterioles?
Regulate BP and BF distribution
What are the adaptations of arterioles?
SM cells to regulate diameter, receptors responsive to dilators and constrictors, innervated by SN fibers, and no parasympathetic nerves
How many layers of SM cells are in arterioles?
What is the feed artery?
Last artery before entering muscle
Upon entering a muscle, the feed artery becomes a _____.
Why is there extensive branching in the arteriolar network?
To aid BF distribution
What is the primary function of capillaries?
Gas, nutrient, and waste exchange
The walls of capillaries are 1 _____ cell thick.
T or F: There is no smooth muscle in capillaries.
What aids exchange in capillaries?
Discontinuous endothelium and large SA
What reduces BF velocity in capillaries?
Capillary density is low in _____.
Capillary density is high in _____.
Why is capillary density high in oxidative muscle?
To facilitate O2 delivery
What are the primary functions of veins?
1. BF from tissues to heart
2. Regulate CO and core body temp
The walls of veins have ____ innervated by SN.
What receptors are in veins?
T or F: There are parasympathetic nerves in veins.
What prevents the backflow of blood in veins?
What do alpha-adrenergic receptors in veins do?
Very responsive to NE, causing the vein to relax and constrict
What is the best index of cardio-respiratory fitness or aerobic capacity?
O2 consumed is used to produce _____.
What is VO2 max?
Maximal O2 uptake
What is VO2 max dependent on?
The ability to deliver and use O2
What is the Fick equation?
VO2 = CO x a-v O2 difference
At rest, what is our VO2 max?
VO2 increases due to...
the increased use of O2 by muscle.
The increase in VO2 is _____.
What is the highest recorded VO2 max?
94 mL/kg/min by Bjorn Daehlie (XC skiier)
What is the average VO2 max for males?
~ 45 mL/kg/min
What is the average VO2 max for females?
~ 38 mL/kg/min
Using a weight-bearing exercise, what units of VO2 max should be used?
Normalize to body weight so mL/kg/min
Using a non-weight-bearing exercise, what units of VO2 max should be used?
When comparing genders, what units should be used for VO2 max?
Clinically, what units of VO2 max should be used?
Metabolic equivalents (1 MET = 3.5 mL/kg/min)
At rest, what percent of CO is going to muscle?
At maximal exercise, what percent of CO is going to muscle?
At rest, what is our venous return?
At maximal exercise, what is our venous return?
How does the ANS increase CO?
Decrease PNA to SA node (increases heart rate), increase SNA to SA node (increases heart rate) and increase SNA to Left Ventricle (increases SV)
How does the ANS redistribute CO?
Increase SNA to non-contracting tissues
How does the ANS increase venous return?
Increase SNA to veins
What is the formula for CO?
CO = HR x SV
_____ withdrawal increases HR.
T or F: CO max varies with fitness.
What is CO max in non-trained people?
What is CO max in trained people?
What is CO max in elite athletes?
CO (O2 delivery) is tightly matched to what?
Metabolic demand (VO2)
What is the CO:VO2 ratio in healthy subjects?
What is average resting HR?
~ 60-80 bpm
During exercise, HR increases in proportion to what?
Metabolic rate (i.e. VO2)
HR max varies with age. What is the formula?
HR is proportional to what?
SNA/PNA (increasing PNA will decrease HR)
Vagal withdrawal from the SA node increases HR to _____.
What do adrenergic receptors do?
What do muscarinic receptors do?
After vagal withdrawal, further increases after 100 bpm are mediated by what?
Increased SNA to SA node
What is stroke volume?
Volume of blood ejected from LV with each heartbeat
What two things increase SV?
Preload and contractility
What decreases SV?
What is preload?
Volume of blood in LV prior to contracting
What is contractility?
Force of LV contraction
What is afterload?
Pressure LV has to overcome to eject blood
What are the 3 determinants of SV?
SV increases during exercise because:
1. Preload increases -> due to increased VR
2. Contractility increases -> due to increased SNA to LV
VO2 increases _____ fold during exercise.
CO increases _____ fold during exercise.
Why must we redistribute CO?
To meet O2 demand
What is right atrial pressure during rest?
What is right atrial pressure during exercise?
What is mean atrial pressure during rest?
What is mean atrial pressure during exercise?
In order to increase VR, there is an increased pressure gradient from _____ to _____.
NE acts on _____ receptors, causing _____.
What two pumps help increase VR?
Respiratory and muscle pumps
What is the muscle pump?
Compression of veins during contraction pushes blood toward heart and valves prevent backflow
When does muscle blood flow (MBF) increase?
Prior to exercise (anticipatory response)
During low intensity exercises, there is increased BF to _____ muscle.
During high intensity exercises, there is increased BF to _____ muscle.
In humans, MBF can increase _____ fold.
What is functional sympatholysis?
Dilators act on SN, reducing NE release and they make alpha receptors less responsive to NE
Dilators act directly on VSM to cause _____.
If there is decreased venous O2, what does this mean?
There are an increased number of active muscle fibers extracting the O2 to produce ATP
What are the 2 theories of CV control during exercise?
1. Signal arises in brain -> central command
2. Signal arises in muscle -> exercise pressor reflex (EPR)
With central command, the signal arising in brain activates _____ and _____ simultaneously.
muscles; CV system
With central command, CV centers increase _____ and decrease _____.
The central command is a _____ mechanism to help match O2 delivery to demand.
With EPR, group III nerves are _____ and respond to _____.
With EPR, group IV nerves are _____ and respond to _____.
EPR is a _____ mechanisn to precisely match O2 delivery to demand.
Describe how baroreflexes work.
Increased arterial pressure -> increased receptor firing -> CNS decreases SNA and increases PNA -> decreases CO and SVR -> decreases arterial pressure (opposite for decreased arterial pressure)
What are baroreflexes?
Provide feedback for BP to keep it normal
Arterial BR are located where?
In aortic arch and carotid sinus
BR send feedback to CV center via what nerves?
Vagus and sinus nerves
What is the goal of BR?
Adjust PNA and SNA to keep BP constant
What is SBP?
Pressure in artery during contraction of heart
What is the primary determinant of SBP?
What is DBP?
Pressure during relaxation phase
What is the primary determinant of DBP?
What is the secondary determinant of DBP?
If SBP increased, what else increased?
If DBP is unchanged or decreased, what happened?
Decreased SVR and increased HR
What is the formula for MAP?
DBP + 1/3(SBP-DBP)
MAP increases to aid what?
What is the operating point (OP)?
Pressure baroreflex is trying to protect
The OP of the baroreflex is reset to a higher pressure during exercise. This allows what?
BP to increase but prevents it from getting to high
What is the primary function of the pulmonary system?
Support metabolism by delivering O2 and removing CO2
What is the conducting zone (CZ) designed for?
Gas flow (no alveoli)
What is the respiratory zone (RZ) designed for?
Gas exchange (alveoli)
What are alveoli?
Air-filled sacs encased in capillaries (blood-gas barrier)
What are the adaptations for the CZ?
Large lumens for low resistance, thick walls to prevent gas exchange, bronchioles wrapped with smooth muscle to regulate resistance, and branching airways to aid gas distribution
How many alveoli are in each lung?
~ 300 million
The alveoli are encased by _____.
The RZ provides a link between what?
Pulmonary and CV system
The diameter of capillaries is _____.
~ 10 micrometers
The diameter of RBCs is _____, so they pass through in a single file.
~ 8 micrometers
At rest, RBCs spend _____ seconds in capillary.
What favors gas exchange in capillaries?
Large SA and slow BF velocity
What is the primary muscle of inspiration?
The contraction of the diaphragm does what?
Elongates chest cavity
What are the accessory muscles for inspiration?
The contraction of the external intercostals does what?
Pulls ribs up and out
What are the accessory muscles for expiration?
Internal intercostals and abdominal muscles
The contraction of the internal intercostals does what?
Pulls ribs down and in
What happens to the diaphragm and external intercostals during expiration?
What do the abdominals do during expiration?
Contact and increase abdominal pressure
When are the abdominals only recruited for expiration?
Only during exercise
Gases flow from _____ pressure to _____ pressure.
During inspiration, alveolar pressure is _____ than atmospheric pressure.
During expiration, alveolar pressure is _____ than atmospheric pressure.
What is atmospheric pressure?
What is alveolar pressure during inspiration?
What is alveolar pressure during expiration?
What is tidal volume?
Volume of air moved in/out of lungs with a single breath
What is IRV/ERV?
Additional volume that can be used as needed
Tidal volume _____ during exercise.
Why does tidal volume increase during exercise?
Progressive decline in IRV and ERV
The breakpoint in ventilation is the _____.
The exaggerated increase in ventilation helps rid the body of what?
What is ventilation determined by?
Tidal volume and breathing frequency
What is ventilation?
Amount of air you move in and out in one minute
Ventilatory threshold occurs at _____ VO2 max.
_____ increases as ventilation increases.
Work of breathing (Wb)
What are two forms of work?
Work to expand chest (determined by tidal volume) and work to overcome airway resistance (determined by breathing frequency)
Respiratory muscles account for _____ of VO2 during maximal exercise.
_____ and _____ increase at onset of exercise.
Tidal volume; breathing frequency
_____ plateaus during heavy exercise.
After tidal volume plateaus, further increases in ventilation are mediated by increased _____.
How is work of breathing minimized?
After tidal volume plateaus, further increases in ventilation are mediated by increased breathing frequency.
T or F: Ventilation increases before the onset of exercise.
When does ventilation reach steady state?
During light and moderate exercise
When does ventilation not reach steady state?
During heavy exercise
Ventilation remains elevated during recovery to...
restore pH. (removes CO2)
What is steady state?
Amount of O2 moving in/out of lungs is precisely matched to blood flow
What is the PO2 of blood entering the pulmonary capillaries?
~ 40 mmHg
What is the PO2 of blood leaving the pulmonary capillaries?
~ 100 mmHg
Why is PaO2 less than PAO2?
1. Diffusion is not 100% complete
2. Some blood bypasses ventilate region of lungs (shunt)
What is the shunt?
Some blood will never get oxygenated because it bypasses the ventilated region. This brings down the PO2 a little bit.
Maintaining a constant _____ is essential for exercise.
Hemoglobin (Hb) consists of _____ protein chains.
Hb can carry _____ molecules of O2.
Saturated Hb carries _____ mL O2/g.
What does it mean if Hb is 100% saturated?
There is an O2 molecules on each heme group.
Where is Hb found?
How is O2 transported?
1. Bound to Hb (99%)
2. Dissolved in blood (1%)
What is a typical male Hb content?
15 g/100 mL blood
What is a typical female Hb content?
14 g/100 mL blood
How do you calculate O2 carrying capacity?
Multiply Hb content x 1.34 mL O2/g + how much is dissolved
What determines % of Hb saturation?
In the lungs, PO2 is _____ and Hb does what?
high; binds O2
In resting muscle, PO2 is _____ and Hb does what?
low; releases ~ 25% O2
In active muscle, Hb releases up to _____ O2.
What is the Bohr effect?
A shift right favors O2 release from Hb
When would the O2 dissociation curve shift right?
When pH drops and temperature increases (both occur during exercise)
CO2 is carried to lungs in 3 ways:
1. Dissolved in plasma
2. Bound to Hb
3. As HCO3-
T or F: CO2 is more soluble that O2.
What is the most important protein carrier?
Why is the reaction slow in plasma?
There is no carbonic anhydrase (CA)
Why is the reaction fast in RBCs?
There is carbonic anhydrase (CA); enzyme that speeds up the reaction
O2 is carried bound to _____ and is dissolved in _____.
Release of O2 at muscle is aided by _____.
CO2 is cleared by the _____.
Central command is a "feed forward" mechanism for rapid increases in _____.
EPR is a "feedback" mechanism to fine tune _____.
What are chemoreceptors?
Monitor levels of O2 and CO2
Besides EPR, what else fine tunes ventilation?
Chemoreceptors in arteries, brain, and lungs
T or F: The ventilatory threshold does not occur at the same % VO2 max for everyone.
Ventilation is lower at any submaximal workload in order to _____.
reduce work of breathing
What is the VO2 adaptation to training?
VO2 during submaximal exercise is similar posttraining. Endurance training increases VO2 max.
What is the CO adaptation to training?
CO during submaximal exercise is similar posttraining. Training increases CO max, which contributes to increased VO2 max.
What is the HR adaptation to training?
HR at rest is lower posttraining. HR max is similar, so it doesn't account for increased CO max.
Why don't you want your HR to get too high?
The filling time will get shorter
What is Training Bradycardia?
HR at rest is lower posttraining
What is the SV adaptation to training?
SV at rest and during submaximal exercise is higher posttraining. Increased SV max accounts for increased CO max.
Posttraining PNA is _____ and SNA is _____ during submaximal exercise.
T or F: Maximal SNA is similar posttraining (HR max not altered).
There is increased preload posttraining due to...
LV hypertrophy, increased BV, and lower HR.
What 3 things occur with cardiac remodeling in an athlete's heart?
1. Increased heart mass
2. LV dilates and walls thicken
3. LV dilation helps increase preload
What is the a-v O2 difference adaptation to training?
a-v O2 difference during submaximal exercise is similar posttraining. Max a-v O2 difference is increased. Enhanced maximal O2 extraction contributes to increased VO2 max.
What 3 things account for increased a-v O2 difference posttraining?
1. Increased capillary density (angiogenesis)
2. Increased mitochondrial density
3. Increased activity of oxidative enzymes
What initiates remodeling in vessels?
Increased BF during exercise
What is arteriogenesis?
Arteries get bigger
Vessel remodeling is mediated by _____.
vascular endothelial growth factor (VEGF)
What does arteriogenesis help?
Increase maximal muscle BF
What are the steps of angiogenesis?
1. Activation of ECs
2. Capillary "sprouting"
3. Migration and proliferation of ECs for tube formation
4. Maturation and stabilization of new capillary
_____ induces capillary remodeling.
Increased capillary density enhances _____.
When does dilation improve in arteries?
Early in training
When does dilation improve in arterioles?
Later in training
What does dilation increase?
What are the CV adaptations with strength training?
There are little or no changes with strength training
Decreased ventilation during submaximal exercise (very little adaptation in the pulmonary system)
Central circulation adaptation
Increased CO max (increased SV max), increased a-v O2 difference
Peripheral circulation adaptation
Arteriogenesis, enhanced dilation, angiogenesis, and increased maximal muscle BF
With EPR, signal for CV adjustments arise in _____.
Endurance training increases VO2 max _____.
The magnitude of increased VO2 to training depends on 3 things:
1. Baseline fitness
2. Intensity, duration, and mode of training
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