Topic 2.1 S&F of the ventilatory system

List the principle structures of the ventilatory system

• Nose, mouth, pharynx, larynx, trachea, bronchi, bronchiole, lungs, alveoli

Outline the function of the conducting airways

• the conducting portion consisting of a series of air passages• Functions include:• air transport• humidification and temperature regulation (conditioning the

air) • filtration and removal of particles • antibacterial and immunologic defense • the sense of smell (via specialised olfactory epithelium) • the production of sound (voice)

DEFINE:• Pulmonary ventilation – the inflow and outflow of

air between the atmosphere and the lungs (aka breathing)

• Total lung capacity (TLC) – volume of air in the lungs after a maximum inhalation

• Vital capicity (VC) – maximum volume of air that can be exhaled following a maximum inhalation

• Tidal volume (TV) – volume of air breathed in and out in any single normal breath

DEFINE:• Expiratory reserve volume (ERV) – volume of air in

excess of tidal volume that can exhaled forcibly

• Inspiratory reserve volume (IRV) – maximal inspired air over and above tidal volume

• Residual volume (RV) – volume of air still contained in the lungs after maximum exhalation

Graph of Lung Capacity Measurements

Explain the mechanics of ventilation in the human lungs

• www.youtube.com/watch?v=SWJHSTAWTCk

cont’d – Role of Boyle’s Law

• Formulated by Robert Boyle (1662) states that at a fixed temperature, the volume of gas is inversely proportional to the pressure exerted by the gas.

• In other words, when a gas is pumped into an enclosed space, it will shrink to fit into that space, but the pressure that the gas puts on the container will increase.

• Boyle's Law can be written out mathematically:P x V = constant

Describe the nervous and chemical control of ventilation during exercise

• Respiratory centers in the brain monitor blood composition.

• During exercise CO2 levels increase. Why?

• CO2 is produced by all active cells in the body• It is a result of cell converting nutrients (glucose)

in to energy (ATP). CO2 is a byproduct of the process called aerobic cellular respiration

Cont’d

• CO2 is detected by chemoreceptors in the respiratory center of the brain (brainstem)

CO2 = lower pH

• How?Carbinic anhydrase

• CO2 + H20 H2CO3 HCO3- + H+

• Free H+ = more acidity

• The lower pH is what the chemoreceptors primarily monitor in the brain’s respiartory center

Cont’d• Neural control also includes lung stretch receptors

• Try it!

Outline the role of hemoglobin in oxygen transport

• Almost 99% of oxygen (O2) in your blood is transported by a large, complex protein that is located in your erythrocytes (red blood cells) called hemoglobin.

Cont’d

• When hemoglobin Hb4 bonds with oxygen, the resulting molecule is called oxyhemoglobin Hb4O8

Explain the process of gaseous exchange at the alveloi

• What are alveoli?• the primary gas exchange units of the lung

Cont’d• Alveoli are 1-cell layer thin and numerous (approx 1

million/lung)

• The alveolar capillaries (the blood vessels tha surround the alveoli) are 1 cell layer thin

• Both structures allow for easy diffusion (movement of a substance from a high concentration to a low concentration)

cont’d