UNIT 3 Flashcards

Question

blood flow through pulmonary circulation (right heart)

Answer 1

Superior/inferior vena cavae -> right atrium -> tricuspid (AV) valve -> right ventricle -> pulmonary valve -> pulmonary arteries -> lungs DEOXYGENATED

Answer 2

Lungs -> pulmonary veins -> left atrium -> mitral (AV) valve -> left ventricle -> aortic valve -> aorta OXYGENATED

Answer 3

epicardium: outer layer myocardium: responsive for contractions endocardium

Answer 4

receives blood supply via coronary arteries high demand for oxygen and nutrients: doesn't do anaerobic metabolism heart receives "just enough" blood to function blockage of coronary blood flow = heart attack (MI)

Answer 5

Right coronary artery, left main coronary artery, circumflex artery, left anterior descending artery

Answer 6

serves as lubricative outer covering

Answer 7

provides muscular contractions that eject blood from the heart chambers

Answer 8

serves as protective inner lining of the chambers and valves

Answer 9

connected by intercalated discs - rapid transmission of electrical signals from cell to cell - heart muscle forms a functional syncytium: unit where they all squeeze together

Answer 10

all one fiber type, similar to type I muscle fibers - more mitochondria than skeletal muscle - heavily reliant on aerobic metabolism

Answer 11

no satellite cells so limited ability to heal/ regenerate after injury

Answer 12

both skeletal and heart muscles have contractile proteins (actin and myosin) heart muscle has a singular nucleus while skeletal muscle shave multiple nuclei heart muscles have intercalated discs, but skeletal muscles have no cellular junctions

Answer 13

Four chambers, but two “pumps” - Left and right side of the heart - Separated by interventricular septum One-way valves prevent backflow of blood - Left ventricular thickness > right ventricle But holds the same volume of blood

Answer 14

Larger mass of myocardium of the left ventricle and septum are needed to pump blood throughout the body, which is under relatively higher pressures

Answer 15

Results from specific exercise stimulus Concentric vs. eccentric hypertrophy

Answer 16

Results from disease state (i.e., hypertension) Associated with loss of myocytes and increased collagen causing fibrosis of the heart

Answer 17

Repeating pattern of contraction & relaxation of heart - Systole – contraction phase Ejection of blood - Diastole – relaxation phase --Filling with blood At rest – diastolic time is longer than systolic time Exercise – duration of both are shorter - Greater reduction in diastole

Answer 18

Isovolumetric ventricular contraction - pressure rises - ↑ Pressure → AV valves close (heart sound 1, “lub”) - Pressure builds, but not yet sufficient to overcome pressure in the arteries so no outflow (volume stays the same) Ventricular ejection - Pressure in ventricle exceeds aorta & semilunar valves open - Blood flows out of the ventricles - At end, blood in ventricle = end-systolic volume (ESV)

Answer 19

Isovolumetric ventricular relaxation - Semilunar valves close (heart sound 2, “dub”) - Ventricular pressure drops with no outflow (volume stays same) Ventricular filling - Pressure in ventricles drops below atrial pressure - Atrioventricular (AV) valves open - Blood flows from atria to ventricles ~70% blood is passive; ~30% is active - At end, blood in ventricle = end-diastolic volume (EDV)

Answer 20

s1: closing of AV valves S2: closing of semilunar valves

Answer 21

same amount of blood but building pressure

Answer 22

building pressure but volume drops

Answer 23

volume of blood that heart gets rid of with one contraction

Answer 24

expressed as systolic/ diastolic - normal is less than 120/80

Answer 25

pressure generated during ventricular contraction

Answer 26

pressure in the arteries during cardiac relaxation

Answer 27

average weighted pressure in arteries: on average what is the pressure in arteries and blood vessels

Answer 28

2/3DBP + 1/3SBP

Answer 29

average MAP is used to determine proper spread of oxygen to body and kidneys

Answer 30

Persistently elevated BP above 130/80 mmHg - Primary (essential) hypertension --Cause unknown (multifactorial) --90% cases of hypertension Secondary hypertension -Result of some other disease process

Answer 31

Left ventricular hypertrophy: muscle gets thicker Atherosclerosis and heart attack: damage to walls Kidney damage: damage to blood vessels in kidney Stroke

Answer 32

Cardiac output - amount of blood pumped by the heart each minute Total vascular resistance - sum of resistance to blood flow provided by all systemic vessels MAP = cardiac output (Q) x total vascular resistance

Answer 33

Average ~5 L (more specific values next slide) Product of heart rate (HR) & stroke volume (SV) -Heart rate – number of beats per minute -Stroke volume – amount of blood ejected per beat Dependent on training state and sex Q=HR X SV

Answer 34

anything that increases HR, SV, blood volume, or peripheral resistance will cause an increase in BP

Answer 35

max heart rate doesn't change w/ exercise resting heart rate decrease and strove volume increase w/ exercise exercise increases max cardiac output

Answer 36

cardiac control that originates from within the heart - pacemaker activity -generates its own electrical signal - no external stimulation

Answer 37

cardiac control by factors originating outside the heart - autonomic nervous system: para sympathetic and sympathetic - endocrine control: epinephrine and norepinephrine (catocolings)

Answer 38

special heart cells generate and spread electrical signal pacemaker cells have an unstable membrane potential called a pacemaker potential - not a resting membrane potential because it never "rests" like skeletal muscle cells - contain unique "funny channels or I channels - combined effect of NA, K, and Ca reach depolarization threshold and AP occurs

Answer 39

pacemaker, initiates depolarization (contraction) stimulates right and left atrial contraction

Answer 40

passes depolarization to ventricles brief delay to allow for ventricular filling

Answer 41

travels along interventricular septum connects atria to left and right ventricle

Answer 42

spread wave of depolarization throughout ventricles stimulates right and left ventricular contraction

Answer 43

Spreads through heart via conduction from cardiomyocyte to cardiomyocyte - Gap junctions are electrical connections between adjacent cells --They consist of a linkage between specialized ion channels on the adjacent cell membranes --They are a component of larger structures called intercalated disks -Allows heart to function as a “syncytium” --Contrasts with skeletal muscle, where every fiber needs nerve innervation

Answer 44

Innervation via vagus nerve (cranial nerve X) Carries impulses to SA, AV nodes -Releases Ach and hyperpolarizes (neg.) cells --Slower spontaneous depolarization -Decreases HR (chronotropic suppression) Decreases HR below intrinsic HR Influence referred to as parasympathetic tone

Answer 45

Innervation via cardiac accelerator nerves Carries impulses to SA, AV nodes, & myocardium -Releases NE and facilitates depolarization -Increases HR (chronotropic enhancement) -Increases force of contraction (inotropic enhancement) Increases HR above intrinsic HR Determines HR during physical, emotional stress Maximum HR: ~250 beats/min

Answer 46

When you start to exercise it starts as a withdraw of parasympathetic than sympathetic kicks in to increase HR the rest of the way

Answer 47

recording of heart’s electrical activity - 12 lead ECG is clinical standard: for different views of heart - Provides different electrical views of heart - Not a measure of a single AP; represents the sum of multiple APs in many myocardial cells

Answer 48

Waves – parts of the trace that go above or below the baseline value Segments – sections of baseline between waves

Answer 49

ventricular depolarization - Signal spreads from AV bundle → Purkinje fibers - Represents ventricular contraction

Answer 50

atrial depolarization - Electrical signal travels SA → AV node - Represents atrial contraction

Answer 51

ventricular repolarization

Answer 52

doesn't actually tell you that the heart is actually contracting but it does say electricity is moving through the heart -> can expect it can, but can't always assume

Answer 53

ventricle depolarization and atria repolarization

Answer 54

ECG recorded during incremental exercise - known as a stress test - physician can observe changes in patient's ECG

Answer 55

Acutely maintained by autonomic reflexes Baroreceptors Located in carotid and aorta Sensitive to changes in arterial pressure (“baro-”) Afferent signals from baroreceptor to brain Efferent signals from brain to heart, vessels Adjustment of arterial pressure back to normal stop shaking

Answer 56

Located in carotid and aorta Sensitive to changes in arterial pressure (“baro-”) Afferent signals from baroreceptor to brain Efferent signals from brain to heart, vessels Adjustment of arterial pressure back to normal

Answer 57

Drop in blood pressure Reduction in baroreceptor activity signaling Afferent signal to medulla oblongata (brain stem) Cardiovascular control center (CVCC) ↓ vagal tone (parasympathetic) ↑ sympathetic activity

Answer 58

Cardiac Output (Q) x Total Vascular Resistance

Answer 59

Heart Rate (HR) x Stroke Volume (SV)

Answer 60

amount of blood ejected per beat

Answer 61

Preload EDV: end-diastolic volume Quantity of blood in the ventricles at the end of diastole afterload Pressure in the systemic arteries, aortic valve Reflects the pressure the heart must pump against to eject blood Contractility Strength of ventricular contraction Influenced by direct SNS stimulation, circulating catecholamines

Answer 62

Dependent on venous return

Answer 63

Greater EDV = more forceful contraction Creates more stretch within the ventricles effects preload for regulation of stroke volume

Answer 64

Venoconstriction via sympathetic nervous system Skeletal muscle pump Respiratory pump Body position important for preload regulation of stroke volume

Answer 65

greater preload = greater stroke volume = greater frank-sterling mechanism = greater cardiac output

Answer 66

Less smooth muscle and very elastic Venous system “stores” much of the body’s blood volume (approximately 2/3 of total) SNS activity results in venoconstriction of the venous system (veins and venules) Venoconstriction results in blood within this “reservoir” being sent back to heart and arterial circulation

Answer 67

Rhythmic mechanical compression with skeletal muscle contraction One-way valves in veins prevent the backflow of blood

Answer 68

During inspiration: ↓ Thoracic (chest) pressure ↑ Abdominal pressure Gradient promotes blood flow towards heart Quiet breathing (rest) aids in venous return, but effect is enhanced with exercise: Greater respiratory rate (more frequent breaths) Greater depth (deeper breathing)

Answer 69

Venus return and plasma value and results in increased stroke volume

Answer 70

resistance in system: blood pressure in aorta and decreases stroke volume

Answer 71

sympathetic nervous system stimulation, increased preload and increases stroke volume

Answer 72

Blood flow through the circulatory system results from pressure differences between the two ends of the system Physical regulation of blood flow to tissues involves interrelationships between pressure, flow, and resistance Blood flow control is important for regulating nutrient delivery to, and waste removal from tissues Greater flow when more delivery and removal is needed; less flow when less is needed

Answer 73

Directly proportional to the pressure difference between the two ends of circulatory system (P1 – P2) Inversely proportional to resistance 𝐁𝐥𝐨𝐨𝐝 𝐟𝐥𝐨𝐰=(∆ 𝐏𝐫𝐞𝐬𝐬𝐮𝐫𝐞)/𝐑𝐞𝐬𝐢𝐬𝐭𝐚𝐧𝐜𝐞

Answer 74

Driving pressure across circulatory system is ~100 mmHg Force that drives flow – provided by contraction

Answer 75

Length of the vessel Viscosity of the blood Radius of the vessel Resistance =(𝐋𝐞𝐧𝐠𝐭𝐡 𝐱 𝐕𝐢𝐬𝐜𝐨𝐬𝐢𝐭𝐲)/(𝐑𝐚𝐝𝐢𝐮𝐬𝟒 )

Answer 76

change R Greatest vascular resistance occurs in arterioles Vasoconstriction or vasodilation – extrinsic control

Answer 77

tonic release of norepinephrine

Answer 78

constricts blood vessels

Answer 79

dilates blood vessels

Answer 80

Arterioles

Answer 81

Richly innervated by the sympathetic nervous system Thick layer of smooth muscle relative to lumen Constriction/dilation of arterioles is key for regulation of pressure and flow

Answer 82

Plasma Liquid portion of blood Contains, ions, proteins, and hormones Cells Red blood cells – contain hemoglobin White blood cells – prevent infection Platelets – blood clotting Hematocrit – percentage of blood composed of cells

Answer 83

Thickness of blood (due to red blood cells) Several times more viscous than water Viscosity ↑ as hematocrit ↑ Plasma volume must ↑ as red blood cell ↑ Occurs in athletes with training or acclimatization Hematocrit and viscosity remain stable Exercise in heat may result in ↑ viscosity

Answer 84

Metabolic need for oxygen in skeletal muscle is significantly greater than for resting Increased O2 delivery accomplished by: Increased cardiac output (Q) Rest: ~5 L/min Exercise: ~ 25 L/min Redistribution of blood flow no

Answer 85

states oxygen consumption (VO2) of a tissue is dependent on: Blood flow to that tissue Amount of O2 extracted from the blood by the tissue VO2 = Q x a-vO2 difference SV X HR peripheral factor central factors

Answer 86

Increases in proportion with intensity up to approximately 40-60% of VO2max Beyond this, it plateaus (no further change) At high HRs, time for ventricular filling ↓ Possible exception: elite endurance athletes

Answer 87

Changes in EDV and ESV both contribute to increases in SV

Answer 88

Body position has a major influence on SV True at rest and during exercise Related to the effect of gravity on venous return Gravity promotes blood pooling in legs, lowering venous return, lower EDV (less Frank-Starling effect) Upright exercise results in increased SV Due to larger EDV, increased venous return Increase in EDV and SV at high HR Supine exercise (for example, swim) results in small increases in SV Due to resting SV being relatively high while supine

Answer 89

increase resistance = length X viscosity/ decrease radius ^4 decrease blood flow = change in pressure/ increase resistance

Answer 90

Increases in proportion to exercise intensity (linear) Maximal HR (HRmax): highest HR achieved in all-out effort to volitional fatigue Highly reproducible Decreases with age Age-predicted HRmax HRmax = 220 − age in years HRmax = 208 − (0.7 × age in years)

Answer 91

Elevated heart rate (and BP) in emotional environment Mediated by increase in SNS Can increase pre-exercise values, but not maximal values Anticipatory response HR increase above resting just before start of exercise Decrease vagal tone (parasympathetic)

Answer 92

Acute exercise ↑ O2 extraction from blood Nearly triples from rest to maximal exercise a-vO2 diff increases because: Greater O2 extraction by active muscle due to an ↑ in amount of O2 used for oxidative production of ATP Redistribution of blood to active tissues - arterial doesn't change concentration of oxygen venus system changes

Answer 93

after SV reaches a plateau then HR is main factor that effects VO2 max

Answer 94

Increased blood flow to working skeletal muscle At rest, 15-20% of cardiac output to muscle During maximal exercise, increases to 80-85% Decreased blood flow to less active organs Liver, kidneys, gastrointestinal tract Redistribution depends on metabolic rate Dictated by exercise intensity

Answer 95

increases VO2 max/ intensity and more blood flows to muscles then kidneys during exercise

Answer 96

blood flow to brain decreases but more blood is delivered so it ends up still beign more blood to brain

Answer 97

Arterioles in skeletal muscle have relatively high vascular resistance at rest (adrenergic sympathetic stimulation) During exercise - Decrease in vascular resistance - ”Recruitment” of capillaries in skeletal muscle

Answer 98

intrinsic ability of local tissues to regulate blood flow to match the metabolic rate - Greater need = greater flow - Local vasodilation triggered by metabolic and endothelial products

Answer 99

increasing workload = increasing blood flow

Answer 100

increase O2 demand (decrease O2) build up of local metabolic by-products: increase co2, K, H, and lactic acid

Answer 101

increase blood flow causes shear stress on endothelium as more blood hits walls of blood vessels secretes vasodilators - nitric oxide (vasodilates), prostaglandins, endothelial-derived hyperpolarizing factor (EDHF)

Answer 102

metabolic regulation and endothelium-mediated vasodilation work hand in hand

Answer 103

Vasoactive molecules released from active skeletal muscle inhibit sympathetic vasoconstriction Reduce vascular responsiveness to 𝘢-adrenergic receptor activation Ex. Endothelium-derived hyperpolarization factor (EDHF) promotes hyperpolarization of smooth muscle cells in arterioles, making it more difficult to constrict no shaking

Answer 104

linearily incrases

Answer 105

diastolic blood pressure doesn't change but systolic blood pressure does

Answer 106

Transient large increases in SBP, DBP, and MAP Up to 480/350 mmHg in central arteries Cause – transient collapse occlusion of vessel in contracting muscle More common when using Valsalva maneuver

Answer 107

At the same oxygen uptake, arm work results in higher: Heart rate – greater sympathetic stimulation Blood pressure – vasoconstriction of large inactive muscle mass

Answer 108

Fitness level Temperature and humidity Duration and intensity of exercise Heavy-intensity intermittent exercise Near maximal HR values are possible

Answer 109

HR decreases slower at end of training interval high intensity/prolonged exercise increases HR more and more and leads to longer recovery of HR

Answer 110

Cardiac output is maintained Gradual decrease in stroke volume - Due to dehydration and reduced plasma volume Gradual increase in HR during prolonged exercise - Particularly apparent in heat - Known as cardiovascular drift

Answer 111

gradual increase in HR during prolonged exercise due to lower stroke volume

Answer 112

Stroke volume decreases so HR increases

Answer 113

movement of air in and out of the lungs mechanical process

Answer 114

exchange of gages in the lungs movement of oxygen into the blood movement of carbon dioxide out of the blood

Answer 115

four continuous and simultaneously occurring steps - ventilation: movement of air from the atmosphere to the alveoli of the lungs - alveolar gas exchange: movement of gases between the alveoli and the blood -circulation: transport of gases in blood to body cells/tissues -systemic gas exchange: movement of gases between blood and cells of the body

Answer 116

functional division - anatomic 'dead space" -passageway for air but no gas exchange -purpose: filter, warm, and humidify air, and transport it to the respiratory zone

Answer 117

functional division - gas exchange between alveoli and capillary blood - very large surface area for gas diffusing - surfactant: reduces surface tension and prevents alveoli from collapsing

Answer 118

Starts with contraction and downward movement of the diaphragm: Increase in volume of the thorax Decrease in intrathoracic pressure Air moves from high pressure (atmosphere) to low pressure (lungs)

Answer 119

External intercostals: elevate and laterally expand ribs "Accessory muscles" include sternocleidomastoid, scalenes, pectorals (anything that attaches to the trunk, shoulder complex, ribs, sternum and makes the thorax bigger) Abdominals: not an inspiratory muscle, but stabilize the abdomen as intra-abdominal pressure increases and help the diaphragm to work more efficiently please stop shaking

Answer 120

Passive at rest Inspiratory muscles relax, all structures return to their starting point Lungs have elastic recoil Decrease in volume of thorax Air moves from high pressure (lungs) to low pressure (atmosphere) Active expiration: Abdominals Internal intercostals

Answer 121

intraabdominal pressure increases and intrathoracic pressure decreases

Answer 122

Measured by assessing the pressure generated during maximal inspiration or maximal expiration For most healthy people: Force necessary for ordinary breathing is a small fraction of maximal force Work of breathing is low and respiratory muscles do not fatigue Increased workload on respiratory muscles during exercise Fatigue can occur with very heavy exercise, prolonged moderate exercise Respiratory muscles can adapt to training just like other skeletal muscle

Answer 123

Ventilation increases proportional to metabolic needs of the active muscle Ve= F X Vt ventilation increases even before exercise depending on moderation of exercise heavy exercise reaches stead state

Answer 124

at low-moderate intensities, mostly tidal volume increases at high exercise intensity, breathing frequency increases

Answer 125

remains relatively constant - slight change during transition

Answer 126

increase in ventilation before muscle contractions anticipatory or feedforward component motor cortex association

Answer 127

slower, gradual increase towards steady-state value

Answer 128

recovery may take several minutes regulated by blood pH, CO2, body temperature

Answer 129

Ve drifts upward due to increased body temperature arterial PCO2 remains constant

Answer 130

linear increase in ventilation but after 75% inflection occurs and we need a huge increase in ventilation and PH drops

Answer 131

exercise intensity above which lactate accumulates in blood when difference in production and clearance of it, can do blood tests but invasive measure

Answer 132

the breakpoint at which Ve and Co2 output begin to increase exponentially with increasing intensity - identified as an inflection on the plot of E vs. exercise intensity Ve increases disproportionately to increase in )2 consumption rise in Ve caused by rapid increase in PCO2 from production of "non-metabolic CO2 - bicarbonate buffering of acid in blood increase in blood lactate likely key stimulus for ventilatory threshold

Answer 133

ventilation threshold and lactate threshold happens around same time

Answer 134

developed by some elite endurance-trained athletes exercising at high intensities

Answer 135

ventilation-perfusion mismatch diffusion limitation due to how quickly blood moves through lungs similar to response observed in exercising patients with severe lung disease

Answer 136

respiratory control center located in medulla oblongata

Answer 137

contains cells that intrinsically fire and control basic rhythm pacemaker cell - prebotxinger complex (prebotc) innervates diaphragm and external intercostals

Answer 138

no active during normal, quiet breathing (passive) during exercise, retrotrapezoid nucleus/parafacial respiratory group (RTN/pFRG) innervates rectus abdominus and internal intercostals

Answer 139

located in pons (brainstem) interacts with both PreBotC and RTN/pFRG to fine-tune and regulate breathing during exercise

Answer 140

CV control center: medulla oblongata in brain stem

Answer 141

central (motor cortex in brain) - rapid response to exercise; parallel coactivation of CVCC but not very accurate peripheral: shower responses and fine tuning of responses - chemoreceptors in muscle - mechanoreceptors in muscle - baroreceptors in arteries

Answer 142

look at volume and flow rate - average title volume - 500 or half a liter

Answer 143

total air you can blow out

Answer 144

air left in lungs: never completely empty

Answer 145

total lung capacity you can move in and out

Answer 146

max amount you can take in

Answer 147

Amount of fresh air that makes it to alveoli - not al inspired air participates in gas exchange (anatomic dead space) alveolar ventilation is the volume of inspired air that reaches the alveoli each minute Va = Vt -Vd increasing total volume with be more effective then increasing breath for total ventilation as the dead space is fixed

Answer 148

when a mixture of gases are present, each individual gas exerts a partial pressure, proportional to the fraction of the mix it represents

Answer 149

alveolar air and pulmonary arteries

Answer 150

movement of gases across a membrane impacted by.. - tissues surface area thickness of tissue diffusion coefficient of the gas driving pressure (magnitude of the pressure gradient

Answer 151

proportional to surface area and driving pressure inversely proportional to tissue thickness diffusion coefficient remain constant but CO2 has greater ease of diffusion than O2

Answer 152

pressure in pulmonary arteries changes as more oxygen is being used leading to a more rapid diffusion

Answer 153

blood flow in lungs

Answer 154

At rest: more blood flow to dependent (lower) areas Due to gravity – therefore, this depends on body position! Upright: best perfusion in base of lung, worst perfusion in apex (top) Supine: best perfusion in posterior lung, worst perfusion in anterior lung During exercise: perfusion is more evenly distributed across lung fields

Answer 155

Goal: maximize the interaction of oxygen-rich air in alveoli and oxygen-depleted blood in pulmonary capillaries Ventilation/Perfusion ratio (V/Q): Indicates matching of blood flow to alveolar ventilation Ideal = 1.0 or slightly higher

Answer 156

apex: reliteively high ventilation, low perfusion V/g is greater than 1 alveolus compressing blood flow

Answer 157

base: relatively low ventilation, high perfusion V/Q is way less than one too much blood flow but smushing alveolus

Answer 158

best matching V/G = 1 pressure of both makes good gas exchange

Answer 159

light to moderate intensity: improves V/Q ration very heavy exercise may worsen V/Q mismatch

Answer 160

Time required for blood to move through the length of the capillary i.e. the time when gas exchange can take place As you move from rest to exercise, heart rate and cardiac output increase More/faster blood flow through pulmonary circulation Transit time decreases Shorter transit time is partially offset because more flow is distributed across all pulmonary capillaries during exercise

Answer 161

Carrier molecule = Hemoglobin (Hb) Protein in red blood cells About 99% of oxygen in blood is bound to hemoglobin, <1% dissolves Main determinant of how much oxygen blood can carry When leaving pulmonary capillaries, hemoglobin is almost always fully loaded (98-100% saturated) with oxygen Each hemoglobin can bind 4 O2 molecules

Answer 162

once the first O2 binds, the other binding sites have increased affinity and more easily bind O2

Answer 163

Deoxyhemoglobin + O2 Oxyhemoglobin Direction of the reaction depends on: Affinity between Hb and O2 PO2 in the blood At the lung: high PO2 favors binding of O2 to Hb At the tissues: low PO2 favors dissociation (release of O2 to tissues)

Answer 164

Decrease in pH (more acidity): lowers Hb-O2 affinity Increase in temperature: lowers Hb-O2 affinity - both of these things happen during exercise which allows oxygen to offload at tissues

Answer 165

Carrier molecule in muscle cells: Myoglobin (Mb) Shuttles O2 from the cell membrane to the mitochondria Myoglobin has a greater affinity for O2 than hemoglobin Remains bound to O2 even at very low PO2 Allows Mb to store O2 as a reserve for muscle O2-Mb dissociation curve shaped differently than O2-Hb curve Loading portion: PO2 = 20 mm Hg Releasing portion: PO2 = 1-2 mmHg

Answer 166

myoglobin's unloading portion, only happens when PO2 is very low and really needed so while hemoglobin is already unbinding, myoglobin still wants it

Answer 167

CO2 is transported for removal in three ways: Dissolved in plasma (10%) Bound to hemoglobin (20%) Bicarbonate (70%) CO2 + H2O H2CO3 H+ + HCO3

Answer 168

pulmonary ventilation removes H from blood by the HCO3 reaction * increased ventilation results in increased exhalation of Co2 - reduces pCO2 in blood - reduces H+ concentration - increases pH decreased ventilation results in increased retention of CO2 - increases pCO2 in blood - increases H+ concentration - decreases pH

Answer 169

signals from higher brain centers afferent input from stretch receptors, mechanoreceptors and muscle chemoreceptors

Answer 170

blood-borne stimuli reach specific chemoreceptors

Answer 171

Impulses from motor cortex (central command) Neural signal passes through medulla and "spill over" causes increase in VE: causes increase in ventilation before exercise has started

Answer 172

located in walls of bronchi and bronchioles hering-beuer reflex: excessive stress causes inhibitory effects that inhibit inspiration

Answer 173

muscle spindles, GTOs, joint pressure receptors

Answer 174

respond to changes in K and H inside and around muscle - not humoral-mediated

Answer 175

located in medulla oblongata stimulated by increase CO2 or H in cerebrospinal fluid increases ventilation

Answer 176

located in aortic and carotid bodies sensitive to increase in PCO2, H, and decrease in PO2 (carotid only)

Answer 177

pulmonary veins since just came from lungs

Answer 178

not sensitive to changes in oxygen (except when reaching hypoxic threshold) but highly sensitive to changes in CO2

Answer 179

PCO2 pH PO2

Answer 180

muscle contractile activity

Answer 181

pH potassium

Answer 182

linear increase in ventilation primary drive - increase in ventilation comes from higher brain centers (control command) fine-tuned by humoral chemoreceptors and neural feedback from muscle

Answer 183

nonlinear (steeper) rise in Ve may result from: increase in blood H that stimulates carotid bodies increase in K, body temperature and body catecholamines may also contribute

Answer 184

peripheral chemoreceptors chemoreceptors

Answer 185

higher brain centers

Answer 186

trained person has 20-30% less ventilation at the same work rate due to more efficant metabolism due to higher blood volume, more hemoglobin and prodce less CO2

Answer 187

Endurance training does not affect lung structure or pulmonary function (diffusion capacity) Structural capacity of normal lung is overbuilt and can adequately maintain CO2/O2 homeostasis during exercise *Pulmonary system is not usually the limiting factor in prolonged exercise (young/healthy subjects) Exercise training does result in decreased VE at fixed submaximal workload Adaptations due to increased aerobic capacity of skeletal muscle, decreased H+ production, decreased afferent feedback stimulating ventilation

Answer 188

Diaphragm is highly oxidative and fatigue-resistant Respiratory muscles can fatigue and may limit performance at very heavy work rates Respiratory muscle training can have a small positive influence on performance Highly trained endurance athletes show decreased fatiguability of respiratory muscles, even without respiratory muscle training no skaing