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exercise physiology and pharmacology > cardiorespiratory > Flashcards

cardiorespiratory Flashcards

1
Q

in which direction do K+ ions move, why, and what effect does this have?

A
  • ions move out of the cell down a concentration gradient due to higher intracellular concentration
  • hyperpolarising effect
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2
Q

in which direction do Na+ and Ca2+ ions move? what effect does this have?

A
  • ions move into the cell due to higher extracellular concentration
  • depolarising effect
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3
Q

what is the difference in depolarisation due to influx pf Na+ ions, and Ca2+ ions?

A

Na+ channels cause rapid depolarisation, which is short-lived due to rapid inactivation
open potassium channels cause sustained depolarisation

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4
Q

what is the primary substrate for ATP in myocardial metabolism?

A

fatty acids

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5
Q

how is ATP supplied during moderate or submaximal exercise?

A

80% by fatty acids

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6
Q

how is ATP supplied during heavy exercise?

A

oxidation of lactate

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7
Q

why is resting heart rate lower than the rate at which the SA node fires?

A

parasympathetic stimulation of the vagus nerve causes a decrease in HR

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8
Q

at which points in exercise is there sympathetic and parasympathetic innervation?

A

parasympathetic activity inhibited (vagal stim) occurs early in exercise
sympathetic innervation increases as exercise increases

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9
Q

what is the effect of switching off vagal stimulation during exercise?

A

rate of depolarisation increases, threshold is reached more rapidly

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10
Q

what is the site where the greatest regulation of blood pressure occurs?

A

arterioles

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11
Q

why is a decrease in pressure important for venous return?

A

arterial blood has a pressure of 90mmHg, this needs to decrease to 1mmHg for return to the heart

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12
Q

what is the mean arterial pressure?

A

93mmHg

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13
Q

where does the resting potential of vascular smooth muscle cells sit?

A

around -40mV

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14
Q

what are the intrinsic mechanisms for control of blood pressure?

A

1) metabolic regulation
2) endothelial regulation
3) myogenic regulation

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15
Q

what are the main cardiovascular adaptations to training?

A
  • increase in heart size
  • increased stroke volume
  • decrease in overall HR and recovery time
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16
Q

what ECG changes occur during exercise?

A 
slight increase in P wave amplitude 
shortening of P-R interval 
shift to the right of the QRS axis
S-T segment depression 
occasional ectopic contractions
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17
Q

what is indicated by an exaggerated ST-depression during an exercise stress test?

A

coronary heart disease

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18
Q

how is maximum heart rate calculated?

A

208 - 0.7 x age

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19
Q

on what does stroke volume depend on?

A
  • venous return
  • ventricular dispensability
  • ventricular contractility
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20
Q

what does external respiration consist of?

A

pulmonary ventilation and pulmonary diffusion

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21
Q

what does internal respiration consist of?

A

transport to and from tissue, capillary diffusion and exchange

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22
Q

what happens during inspiration?

A
  • diaphragm flattens, external intercostal muscles contract

- volume in the lung increases, pressure decreases, causing air to move in

23
Q

what happens during expiration?

A
  • diaphragm relaxes, external intercostal muscles relax

- volume in the lung decreases, pressure increases and air moves out

24
Q

how does the process of expiration change in exercise?

A

it becomes an active process, internal intercostal muscles pull the ribs back down to increase rate of expiration

25
Q

what is tidal volume?

A

volume moving in and out during each breath

26
Q

what is vital capacity?

A

greatest amount of air that can be expired after maximal inspiration

27
Q

what is residual volume?

A

amount of air retained in the lungs after maximal expiration

28
Q

how is total lung capacity calculated?

A

sum of VC and RV

29
Q

what is the role of the bronchial tree?

A

increases surface area over which gaseous exchange can occur

30
Q

what causes bronchoconstriction?

A

cold, allergens, parasympathetic activity

31
Q

what causes bronchodilation?

A

sympathetic activity, adrenaline/noradrenaline, exercise, B2-agonists

32
Q

what are alveoli?

A

air sacs at the end of bronchioles

33
Q

how much blood does the pulmonary circulation get per minute?

A

4-6L at rest

34
Q

why do pulmonary vessels have less smooth muscle than systemic vessels?

A

pressure drop is much smaller

35
Q

how does a change in partial pressure facilitate gas exchange at the alveoli?

A

oxygen moves in due to lower pressure, CO2 moves out into the lungs

36
Q

what is daltons law?

A

total pressures of a mixture of gases equals the sum of the partial pressures of the individual gases in that mixture

37
Q

how are oxygen and carbon dioxide transported in the blood?

A

O2: 2% diffused freely in the blood 98% combined with Hb
CO2: 60-70% dissolved in the blood as bicarbonate ions, 7-10% dissolved as free CO2, 20% of this binds Hb

38
Q

describe how partial pressures facilitate movement of oxygen into arterial blood

A

pO2 in the pulmonary arterial blood is lower than alveolar gas, therefore O2 diffuses into the blood

39
Q

what is the role of myoglobin?

A

transfers oxygen into the cell, and to mitochondria for oxidative phosphorylation

40
Q

how is breathing regulated?

A

autonomic and voluntary control. respiratory control centres in the medulla oblongata and pons

41
Q

what are the types of chemoreceptors?

A

central: sense pCO2, pH
peripheral: sense pO2, pCO2 and pH

42
Q

what are the initial and later changes in pulmonary ventilation during exercise caused by?

A

initial changes due to neural inputs

later changes occur due to changes in chemical composition of the blood gases/pH

43
Q

what does ventilatory threshold refer to?

A

the process by which ventilation will increase disproportionately to O2 consumption in order to remove excess CO2

44
Q

name 3 respiratory disorders which limit the ability to exercise?

A
  • Asthma
  • Fibrosis
  • COPD
45
Q

what is pulmonary hypertension? what are the effects of this?

A

high blood pressure in the arteries of the lungs

arteries become less compliant, reduced blood flow, heart failure, death

46
Q

what does the Nersnt equation allow? what does it assume?

A

calculation of resting potential from [intracellular] and [extracellular]. assumes the membrane is only permeable to one ion

47
Q

how is contraction coupled in cardiac muscle?

A

each cell is connected through gap junctions

48
Q

how is vasomotor tone regulated?

A

variable resting potential of around -40mV can be modulated. Ca2+ and Na+ influx via non-selective channels cause vasoconstriction, potassium influx causes dilation

49
Q

what causes a decrease in stroke volume?

A

decrease in vascular resistance due to vasoactive metabolites

50
Q

what is sympatholysis?

A

balance of sympathetic stimulation that causes an increase in contraction and decrease due to local metabolism

51
Q

what causes long-QT syndrome?

A

mutations to Ikr or Iks channels

52
Q

what is the impact on cardiac function associated with long-QT?

A

the heart fails to contract as a syncytium.

53
Q

what is hypertrophic cardiac myopathy?

A

where cardiomyocytes are misaligned, commonly caused by mutations to B-myosin heavy chain, myosin binding protein C, cardiac troponin T or tropomyosin. causes force generation impairment and fibrosis

54
Q

how does long qt cause sudden cardiac death?

A

reversion to irreversible ventricular fibrillation

exercise physiology and pharmacology (11 decks)

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