Cardioresp

• What is the conducting zone


  The larger airways that warm, humidify, and filter air without participating in gas exchange (i.e. anatomic dead space)
• Typical VT, anatomical dead space, alveolar gas and pulmonary blood volume values, total ventilation:

  VT: 500ml

  Dead space: 150ml

  Alveolar gas: 3000ml

  Pul blood: 70ml

  Total vent: 7500ml
• Minute ventilation/Total ventilation equation

  Tidal volume x breathing freq
• How is VT calculated

  deadspace volume + alveolar volume
• Whats the difference between anatomical deadspace and physiological deadspace

  Non exhanging airways vs areas of the lung which arent exchanging like a shunt
• What is the partial pressure of oxygen at sea level

  160mmHg

  
  

  Calculated by 0.21 (% dry air oxygen content) x 760mmHg (atmospheric pressure)
• What are the main 2 types of haemoglobin

  Hb A → 97% of Hb in adults

  Hb F → dominant form in fetus
• What are the 3 transport mechanisms for CO2

  1. Dissolved CO2

  2. Bicarbonate

  3. Carbamino compounds
• What are 2 limitations in performance athletes in relation to ventilation

  Exercise induced hypoxemia

  Arterial desaturation
• What is the purpose of the cardiovascular system

  Load up the blood with oxygen

  Unload CO2

  Perfuse the organs of the body
• Main differences between the pulmonary and systemic circulation

  Pulmonary is low pressure and low vascular resistance

  Systemic is high pressure and high vascular resistance, and has higher volume of blood
• What law is related to pulmonary vascular resistance

  And what does it mean?

  Darcy's Law

  As cross sectional area increases, pressure and blood velocity decreases for laminar flow
• How can pulmonary resistance become lower

  Recruitment → as more vessels open more vessels are perfused so deeper breathing

  Distension → vessels are stretched
• What variables does Bernoulli's theory involve


  Pressure energy of blood

  Gravitational potential energy

  Kinetic energy

  
  

  States that an increase in speed of a fluid occurs simultaneously with a decrease in static pressure or the fluids potential energy
• What are the 4 stages of the cardiac cycle

  Ventricular filling (2/3 of the cycle)

  Isovolumetric contraction

  Ejection

  Isovolumetric relaxation
• What are 4 factors that SV is determined by

  Volume of venous return

  Ventricular distensibility

  Ventricular contractility

  Aortic or pulmonary pressure
• What is inotropy and chronotropy

  Ionotropy= increase contractility

  Chronotropy= increase HR
• What 4 key relationships influence arterial pressure

  1. Pulse pressure

  2. Compliance

  3. Mean blood pressure

  4. TPR
• What are the 3 tiers of arterial diameter and tone control

  Autoregulation → myogenic response

  Vasoactive agents → endothelial dependent

  Extrinsic regulation
• What is cardiac output preload, contractility and afterload


  Preload: force that stretches the cardiac muscle prior to contraction

  Contractility: how hard we can push blood out

  Afterload: the amount of pressure (myocardial stress) that the heart needs to exert to eject blood during ventricular contraction
• What % of VO2Max does SV plateau at and why does it plateau

  50-60%

  Due to increase in HR for preload which inc contractility and reduces afterload to increase oxygen utilisation at the muscle
• What are the extrinsic control mechanisms related to blood vessels

  Vasomotor nerves → vasoconstrictor/dilator

  Hormones → adrenaline, ADH, angiotensin II
• Name some vasoactive factors known to result in vasodilatation

  K+

  Hypoxia

  Adenosine

  Inorganic phosphate

  Hydrogen peroxide
• Whats the difference between resistance and capacitance vessels

  Resistance vessels include small arteries and arterioles

  Capacitance include small and large veins and have greater capacity to distend, they also may accommodate 20x more blood than resistance vessels
• Where are the primary resistance sites and what is the main key difference


  Sit in the terminal arteries and arterioles

  Terminal arteries have sympathetic innervation and control blood flow to capillaries whereas arterioles have none
• What type of flow do RBCs travel by in capillaries

  Bolus flow → singular flow separated by plasma
• What is metabolic hyperaemia

  Body adjusts blood flow to meet metabolic demands e.g. oxygen demand
• What are the 3 classes of capillary and their main roles

  1. Continuous capillary → brain, nervous, muscle, lungs → moderate permeability

  2. Fenestrated capillary → exo+endocrine glands → high water permeability

  3. Discontinuous (sinusoidal) capillary → modified to have a gap to let RBCs through → liver, spleen, bone marrow
• Define VO2Max


  Highest rate at which oxygen can be taken up and utilised by the body during severe exercise
• Primary criteria for identifying VO2Max

  Plateau in VO2

  VO2 peak rather than plateau
• Secondary criteria for identifying VO2Max


  Plateau in VO2 despite an increase in work rate

  Blood lactate level greater than 8mmol/L

  Hr Max reached

  Perceived exertion on Borg scale

  RER> or equal 1.15
• Difference between absolute and relative VO2Max values

  Relative values are statue and mass adjusted and measured in ml/kg/min whereas absolute is L/min
• What are some limitations of maximal oxygen uptake

  Ventilatory limitations → transit time → only seen in highly trained athletes

  SV: inc SV inc oxygen carrying capacity

  Peripherally capillary density → to increase transit time

  Diffusion gradient

  Mitochondria → inc mito=inc VO2Max

  
  

  Q is primary limiter especially in trained individuals
• VO2Max limitations


  Central= convection → Q and CaO2

  Peripheral= O2 extraction → diffusion and O2 utilisation
• What are the 3 stages of pulmonary oxygen kinetics

  1. Cardio-dynamic

  2. Primary

  3. Steady state
• What are the implications of greater oxygen deficit, when the onset of exercise is rapid and demands aren't met quickly

  Increase PCr breakdown

  Increase ADP and Pi accumulation

  Increase H+ and lactate accumulation

  Increase glycogen depletion
• What is the slow component


  Incremental oxygen consumption despite constant workload

  Seen with reduced mechanical coupling efficiency, recruitment of lower efficiency motor units, higher metabolic requirements of fatiguing fibres
• What % VO2Max is lactate threshold and steady state usually reached at?

  LT= 50-70%

  Steady= 80-90%
• What impact does modality of exercise have on VO2Max values

  Training status and experience can affect values, increased blood flow and oxidative capacity are associated with treadmill testing.

  Difference in exercise modality is attributed to SV not HR.

  Differences in body position and muscles used → treadmill vs ergometer
• Name some central and peripheral limitations to performance

  Central: pulmonary diffusion, CO, Q and volume

  Peripheral: Muscle diffusion capacity, mitochondrial and capillary density