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EPHE 441 > Cardiovascular and pulmonary > Flashcards

Cardiovascular and pulmonary Flashcards

1
Q

How does the cardiovascular system adapt to meet the increased oxygen demands during exercise?

A

Increase in cardiac output and redistribution of blood flow from inactive organs to skeletal muscle

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2
Q

What are the 3 purposes of the cardiovascular system?

A

The transportation of O2 to tissues and removal of waste, transport of nutrients to tissue, regulation of body temperature

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3
Q

List the three layers of the heart wall, their defining characteristics, and functions.

A

Epicardium: Serves as lubricative outer covering. Has a serous membrane including blood capillaries, lymph capillaries, and nerve fibers.

Myocardium: Msc contractions that eject blood from heart chambers. Consists of cardiac msc separated by CT.

Endocardium: Protective inner lining of chambers and valves. Endothelial and thick subendothelial layer of elastic and collagenous fibers.

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4
Q

List 3 structural differences between skeletal muscle and cardiac muscle.

A

1) Smsc= multiple nuclei, Cmsc=single
2) Cmsc=cellular junctions (intercalated discs), Smsc=no
3) Smsc fibers=elongated, no branching, Cmsc= shorter, branching

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5
Q

What is the function of an intercalated disc?

A

Connect heart msc fibers. Permit transmission of electrical impulses between one fiber and another. Also allow ions to transfer between fibers. Allows for connected fibers to contract as a unit during depolarization. AKA functional syncytium

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6
Q

Why do the ventricles not contract when the muscle fibers in the atria are stimulated?

A

They are separated by a layer of CT that does not allow for electrical transmission.

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7
Q

List 3 functional differences between skeletal muscle and cardiac muscle?

A

1) Cmsc= mostly AE energy production, Smsc= ANE and AE
2) Cmsc= Ca2+ from SR and extracellular Ca2+, Smsc= SR
3) Cmsc= no regeneration potential, no satelellite cells. Smsc= some via satellite cells

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8
Q

List 5 factors that when increased, lead to an increase in blood pressure

A

Blood volume, HR, Stroke volume, Blood viscocity, Peripheral resistance

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9
Q

Describe how the parasympathetic nervous system influences heart rate through innervation of the vagus nerve.

A

The vagus nerve fibers (from medulla oblongata) stimulate both SA and AV nodes. When stimulated, nerve endings release ACH which decreases activity in both nodes due to hyperpolarization. Slows HR.

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10
Q

What is the physiological significance of heart rate variability?

A

Time variation between heart beats reflects autonomic NS control of the heart. Noninvasive screening tool for sudden cardiac death, heart failure, MI, high BP

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11
Q

Describe sympathovagal balance.

A

The ability to switch between ParaSymp and Symp, relfected in beat-to-beat changes

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12
Q

List and describe the three principal mechanisms involved in the regulation of venous return.

A

1) Venoconstriction: increases venous return by decreasing diameter. Occurs via Symp reflex. Result of symp constriction of sm.msc in vessels
2) Muscle pump: Result of mech. action of rhythmic sk. msc contractions during exercise. Msc contraction compresses veins increasing return to the heart. Doesn occur during isometric contractions.
3) Respiratory pump: rhythmic pattern of breathing also mechanical pump. during inspiration pressure in thorax lower than abd. cavity. Thus increasing venous return as presure is lower in chest than abd. Enhanced with higher resp. rate, especially during upright exercise

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13
Q

What is the principal variable that influences end diastolic volume?

A

rate of venous return to heart

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14
Q

What regulates stroke volume?

A

EDV, average aortic BP, strength of ventricular contraction

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15
Q

Describe the differences between the distribution of cardiac output during rest and maximal exercise.

A

During rest the majority of the blood flow is to the GI system and kidneys. During work almost all the blood goes to the skeletal msc.

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16
Q

Describe the Frank-Starling and Contractility effects.

A

Increased EDV stretches the cardiac muscle to create a more optimal overlay between the actin and myosin filaments. This causes a greater force of contraction causing an increased stroke volume.

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17
Q

What is VO2?

A

The amount of oxygen that can be used.

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18
Q

What are some physiological factors that affect VO2 max?

A

1) Delivery of O2 to working msc (cardiorespiratory)

2) utilization of O2 by working msc (metabolic aerobic)

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19
Q

How do betablockers impact heart rate?

A

Betablockers compete with epi and norepi for the beta-adrenergic receptors. They decrease HR and contractility which lowers the myocardial O2 demand.

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20
Q

What is end systolic volume?

A

The amount of blood in the ventricles at the end of systole.

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21
Q

How does end systolic volume relate to stroke volume?

A

By increasing contractility. Through innervation of symp nervous system, epi is released causing CA2+ to be released from SR

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22
Q

How does endurance training alter cardiac output?

A

1) Plasma volume increased (main factor)
2) Increased force of contraction (Frank-Starling)
3) Increased contractility due to calcium release (during exercise only)

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23
Q

How does resistance training alter cardiac output?

A

Ventricular wall thickens with both endurance and strength training. Increased mass helps maintain SV and Q

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24
Q

Describe some of the processes that trigger autoregulation.

A

Increased body temp, elevated CO2 levels, increased lactate/lower pH, release of adenosine, presence of Mg2 or K+, or ACH

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25
Q

What is the aVO2 difference?

A

The difference between the arterial VO2 and venous VO2. AKA the amount of O2 being used by skmsc

26
Q

What factors is the O2 removal rate in tissues dependent on?

A

Capillary density, myoglobin content, mitochondria volume and oxidative capacity, msc fiber type, PO2 gradient from capillaries to tissues

27
Q

What is the difference in NS control for vasoconstriction and vasodilation?

A

Vasoconstriction is SNS, Vasodilation is autoreg.

28
Q

How does capillary recruitment help improve oxygenation of working muscles?

A

During exercise capillaries become perfused. Leads to increased blood flow to msc, reduces speed of blood flow, and increases surface area available for gas exchange at tissue level

29
Q

What does nitric oxide do during exercise?

A

Promotes smmsc relaxation leading to vasodilation and increased blood flow

30
Q

Where is nitric oxide produced?

A

In the endothelium of arteries

31
Q

What needs to be done to ensure adequate blood flow to muscles?

A

1) Adequate cardiac output
2) distribute blood to working msc/divert from less active areas
3) maintain BP

32
Q

How is MAP calculated?

A

Cardiac output x total peripheral resistance

33
Q

Describe the differences between pulmonary and cellular respiration.

A 
Pulmonary = ventilation, exchange of O2 and CO2 in lungs.
Cellular = O2 utilization and CO2 production
34
Q

What is the purpose of the respiratory system during exercise?

A

Gas exchange between environment and body, and acid-base balance

35
Q

What is tidal volume?

A

amount of air moved per breath

36
Q

What is alveolar ventilation?

A

volume of air that reaches respiratory zone

37
Q

What is dead-space ventilation?

A

volume of air remaining in conducting airways

38
Q

What is the ventilation-perfusion ratio?

A

indicates matching of blood flow to ventilation. Apex lower than base

39
Q

What are the effects of pH on the O2-Hb dissociation curve?

A

-decreased pH lowers Hb-O2 affinity, results in rightward shift of the curve, favors offloading of O2 to tissues (Bohr effect)

40
Q

What are the effects of temperature on the O2-Hb dissociation curve?

A

increased temp lowers Hb-O2 affinity, results in rightward shift

41
Q

What are the effects of 2-3 DPG on the Hb-O2 dissociation curve?

A

byproduct of RBC glycolysis, may result in rightward shift. Not a major cause

42
Q

What does myoglobin do?

A

Responsible for O2 from membrane to mitochondria, O2 is reserved for muscle, buffers O2 at start of exercise until cardiopulmonary system increases O2 delivery

43
Q

What is the difference between oxyhemoglobin and deoxyhemoglobin?

A

Oxyhemoglobin has O2 bound to it, deoxyhemoglobin does not

44
Q

What is the normal hemoglobin concentration for a healthy male and female?

A

150g/L male and 130 g/L female

45
Q

What factors influence the direction of the O2-Hb dissociation curve?

A

1) PO2 in blood

2) affinity or bond strength between Hb-O2

46
Q

Describe some of the unique features of the sigmoidal shaped Hb-O2 dissociation curve.

A

%HbO2 increases sharply up to an arterial PO2 of 40 mm Hg. PO2 above 40 mm Hg, increases slowly until plateau at 90-100 mm Hg, %HbO2 approximately 97%

47
Q

Describe the difference of tissue O2 utilization during rest and intense exercise.

A

Rest: ~25% O2 in blood delivered to tissue. During intense exercise mixed venous PO2 can decrease 18-20 mm Hg and peripheral tissues can use up to 90% of O2 carries by Hb.

48
Q

How is CO2 transported in the blood?

A

1) Dissolved CO2 ~10%
2) CO2 bound to Hb (carbanohemoglobin) ~20%
3) Bicarbonate

49
Q

How does ventilation effect acid-base balance?

A

Increased ventilation results in exhalation of additional CO2, lowering PCO2, raising pH

50
Q

What occurs when the ventilatory threshold is reached (TVent)?

A

Where ventilation switches from rising incrementally to rising exponentially.

51
Q

Why does hypoxemia occur in some highly trained athletes?

A

Possibly ventilation-perfusion mismatch and diffusion limitations

52
Q

What is one potential factor that may limit diffusion in elite athletes?

A

A reduced time that RBC’s spend in the pulmonary capillary due to a high cardiac output.

53
Q

Describe how ventilation changes during an incremental step test.

A

At rest/minimal exertion frequency and tidal volume are low. During moderate exercise, tidal volume increases significantly while frequency only slightly increases. During intense exercise tidal volume maxes out and frequency increases.

54
Q

Why is it beneficial to begin increasing tidal volume before frequency?

A

Increasing tidal volume minimizes the amount of dead space ventilation occurs and maximizes alveolar ventilation. Va = (Vt-Vd). Once tidal volume has been maximized, increasing frequency further maximizes Va by ensuring the body receives the excess O2 it needs to produce ATP in working msc via oxidative phosphorylation

55
Q

During prolonged exercise in excess heat, why does ventilation drift upwards?

A

Due to the influence of rising body temp on the respiratory centres

56
Q

At what point does Vt usually occur?

A

Between 50-70% VO2 max

57
Q

What is the prevalence of exercise induced hypoxemia in elite athletes?

A

40-50%

58
Q

How do the central and peripheral chemoreceptors influence humoral chemoreceptor input to the respiratory centre?

A

Central is sensitive to increases in PCO2 and decreases in pH. Peripheral (carotid bodies most important) are sensitive to increases in PCO2 and decreases in PO2 and pH.

59
Q

What are the carotid bodies and where are they found?

A

Found in carotid artery, primary peripheral chemoreceptors.

60
Q

Where does the primary drive to increase ventilation occur?

A

Central command. Especially humoral chemoreceptors and neural feedback from working msc.

EPHE 441 (6 decks)

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