Respiratory

• What is the physiological dead space actually measuring?

  The physiological dead space is a FUNCTIONAL MEASUREMENT based on the ability

  of the lungs to eliminate CO2

  It is defined by the Bohr equation

  VD/VT = (PaCO2 -PeCO2)/PaCO2
• What is closing volume?

  closing volume is the volume at which basal airways close
• What is internal respiration vs. external respiration?

  Internal respiration = oxidative phosphorylation

  External respiration = transporting oxygen to the mitochondria and

  transporting carbon dioxide from the mitochondria to atmosphere
• How is O2 and CO2 flow across a membrane quantified?

  Flow moles/s

  Flow is proportional to concentration difference across this barrier
• What is Henrys Law?

  Concentration of a dissolved gas is proportional to its partial pressure in the gas

  phase

  C = kP

  C = concentration of dissolved gas

  k= Henrys Law constant

  P = partial pressure of the gas
• What is Daltons Law?

  Dalton's Law states that the total pressure exerted by a mixture of non-reacting gases is equal to the sum of the partial pressures of each individual gas
• What is the formula for daltons law?

  The total pressure of a mixture of gases is the sum of their individual

  partial pressures

  P = sum Pi = p1 + p2 +... Pn
• What is ficks first law

  Ficks first law relates to the diffusive flux to the gradient of the concentration

  The magnitude of flux is related to the concentration gradient

  J = -D dr/dx

  J = diffusion flux

  D = Diffusion coefficient

  dr/dx= concentration gradients
• How is convection different from simple diffusion?

  Movement of particles due to temperature difference vs. movement of particles from high to low concentration.

  Simple diffusion where solutes more short distances down concentration

  gradient on is the movement of particles through a substance, transporting

  their heat energy from hotter areas to cooler areas

  (Convection is a method of heat movement)

  In humans, the bulk phase is the atmosphere and the external

  convective system is an air pump that includes the chest wall,

  respiratory muscles and the passages through which air flows
• What is ventilation?

  The process of moving air into and out of the lungs
• What is the internal convective system?

  The circulatory system that maximises flow of O2 and CO2 across the

  gas exchange barrier by delivering, to the inner surface of this barrier

  And blood that is as low as possible PO2 and as high as PCO2 level as practical
• How does surface area affect diffusion?

  Surface area affects diffusion by increasing the rate of diffusion.

  The passive flow of O2 and CO2 across a barrier is proportional to the concentration gradient and the area to the barrier

  Flow proportional to change in pressure x Area
• What is the inbuilt redundancy in the rate of diffusion and why?

  The lung surface is so large and thin that O2 and CO2 transfer is 3 fold

  faster than necessary

  This in built redundancy is important for exercise, altitude and old age
• How does Hb affect CO2 and O2 carrying capacity in the blood?

  Haemoglobin is a specialised metalloprotein that, via the metal ion, reversibly binds 02 to greatly increase the carrying capacity of blood for 02

  Haemoglobin coordinate a porphyrin ring that contains iron
• What 6 steps/conditions must be met to allow for external respiration?


  1)An air pump

  2)Mechanisms for carrying CO2 and O2 in the blood

  3)A surface for gas ex change

  4)A circulatory system

  5)Mechanism for local regulating distribution of ventilation and perfusion

  6) mechanism for regulating control of ventilation
• In regards to the air pump, what mechanism does gas exchange occur?

  Air pump

  · External convective system

  · Upper resp tract

  · Large pulmonary arteries

  · Muscles of respiration

  -thoracic cavity

  -skeletal muscles

  · Alveolar ventilation

  · Inspiration occurs when muscles contract and increase the volume of the

  thoracic cavity

  ↓

  lowers intrathoracic pressure And alveoli expand passively

  ↓

  lowers alveolar pressure

  ↓

  Air flows from environment to the alveoli down a pressure gradient
• What is the parietal pleura?

  Is the wall of the pleural sac that is furthest from the lung

  It contains blood vessels that produce an ultrafiltrate of the plasma called pleural fluid
• What is the visceral pleura?

  The inner layer of the pleura that covers the lungs.

  It is the plea that lies directly on the lung and contains lymphatics that drain

  the fluid from the pleural space
• What is pleural fluid and what is the normal volume?


  Pleural fluid is a liquid that fills the space between the two layers of the pleura, which are the membranes that line the lungs and chest cavity. The normal volume of pleural fluid is around 10-20 milliliters.
• When does pleural effusion develop and What does it do to lung volume?

  Pleural effusion develops when there is an abnormal accumulation of fluid in the pleural space. It can compress the lung and reduce lung volume.

  Pleural effusion develops when the rate of fluid production is higher than the rate of

  absorption
• What are the conducting airways?

  Trachea is generation zero

  Mainstem bronchi is generation one

  Bronchi is generation two to ten

  Bronchi have cartilage

  Bronchioles start at generation eleven and the non conducting zones

  end at terminal bronchioles at generation sixteen

  Bronchioles have no cartilage

  Generation sixteen is called terminal bronchioles but comes before

  respiratory bronchioles
• What are the alveolar air spaces?

  Bronchides from generation seventeen, called respiratory bronchioles, are involved in gas exchange

  Respiratory bronchioles start at generation seventeen and end at generation

  nineteen

  Alveolar ducts start at generation twenty and end at generation twenty-two

  Alveolar says are in generation twenty-three
• When does smooth muscle appear in the respiratory generations?

  Smooth muscle appears in generation seventeen
• How do bronchioles stay open if they lack cartilage?

  Cartilage free bronchioles maintain a patent lumen only because of the

  outward fathering/radial traction
• How does air flow in the conducting airways?

  Air moves via convention to those regions that participate in gas exchange
• How much volumeis in the anatomical dead space?

  150mL males

  100mL females
• What is a terminal respiratory unit or primary lobule?

  A terminal respiratory unit/primary lobule is an aggregation of all

  airways arising from a single terminal bronchiole along with associated blood

  and lymphatic vessels
• What is the fundamental unit of gas exchange?

  The alveolus is the fundamental unit of gas exchange
• What shape are alveoli?

  Hemispheric structures
• What size are alveoli?

  75-300 micro m in diameter
• What is the cross sectional area of the alveoli?

  ~300 million alveoli have a combined surface area of 50-100m2

  and an aggregate maximal volume of 5-61 in the two lungs
• What are the two types of epithelial cells in the alveolus?

  type 1 pneumocytes

  type 2 pneumocytes
• What are type 2 pneumocytes?

  Cuboidal epithelial type 2 cells exist in clusters and are responsible for

  pulmonary surfactant
• What are type 1 pneumocytes?

  Type 1 pneumocytes are thin, flat cells that make up the majority of the alveolar surface in the lungs. They are responsible for gas exchange.
• What happens to type 1 and 2 pneumocytes post injury?

  Type 1 pneumocytes undergo apoptosis, while type 2 pneumocytes proliferate and differentiate into type 1 pneumocytes.
• where is the pulmonary capillary in relation to the alveoli?

  The pulmonary capillaries are usually sandwiched between two alveolar air spaces

  Blood runs as an almost uninterrupted sheet that flows like a twisted ribbon

  between abutting alveoli
• What are pores of Kohn?

  Pores of Kohn are small openings in the walls of adjacent alveoli in the lungs, allowing for collateral ventilation.
• What is the blood supply to the lung?

  Pulmonary and bronchial arteries
• What is the diameterof the pulmonary capillary?

  Internal diameter of 8 micro m
• What are the non respiratory functions of the lung?

  olfaction

  warming and filtering large particles

  Blood Reservoir

  Filter small emboli from the blood

  Metabolism

  · Inactivate

  · Activate

  immune function