describe the passageway of air through the lungs
trachea - bronchi - bronchioles - terminal bronchioles - respiratory bronchioles - alveolar ducts and alveoli
what are the two divisions of airways
conducting zone (trachea to terminal bronchioles) and respiratory zone (respiratory bronchioles to alveoli)
what is the function of epithelial surfaces of the airways
they contain cilia and secrete mucous (as well as water fluid that keeps mucus moving)
what do cilia do in the lungs
carry dust-containing mucous out of airway
explain the relationship between pressure in cardiac and pulmonary cycle
blood is pumped from heart to lungs via pulmonary artery; thus pulmonary arterial pressure changes based on systole or diastole
what causes pressure to decrease in pulmonary arteries and veins
frictional resistance during blood flow
how does Boyle's law relate to breathing
if lung volume increases, pressure in lung decreases
what drives gas movement
pressure difference between lungs and atmosphere
what are the two opposing forces that are involved in breathing
elastic recoil of the thoracic wall and lungs; these forces move the parietal and visceral pleura slightly apart which eases pressure
how does inspiration impact intrapleural pressure
decreases it because it moves the thorax outward
how does expiration impact intrapleural pressure
increases pressure because thorax moves inward, opposite forces are reduced, and thus pressure increases
Compare inspiration and expiration for the following: volume of bronchial treevolume of alveoliresistance to airflow in airways
volume of bronchial tree increases with inspirationvolume of alveoli increases with inspirationresistance to airflow is lower with inspiration
what factors increase the resistance to ventilation
increased airway resistance and decreased pulmonary compliance
describe pulmonary compliance
change in volume for a given change in pressure; in terms of the lungs this refers to its ability to expand; if it has high compliance, it easily expands
what two factors decrease pulmonary compliance
elastic recoil of lung and surface tension
where does respiration (gas exchange) occur
occurs between the alveoli and vascular supply (capillaries) in the lung
what type of diffusion occurs in gas exchange
simple diffusion dictated by pressure gradients
what does spirometry measure
rate of air flow in and out of the lungs
define total lung capacity
total amount of air the lung can hold
define vital capacity
maximum volume per breath
define tidal volume
total volume of inspired air with each breath
define respiratory quotient
the ratio of carbon dioxide produced to oxygen consumed
what is hemoglobin
protein found in red blood cells which is composed of four subunits (heme + polypeptide) which can each carry one O2 molecule
describe hemoglobin subunits
there are four, each one has a heme and polypeptide; each heme has one atom of iron which binds the oxygen
what is an inhibitor of hemoglobin-oxygen binding
carbon monoxide (200x the affinity for oxygen)
what determines hemoglobin saturation
temperature, pH, amount of CO2 in blood, and 2,3-DPG
if an oxygen dissociation curve shifts right what does this mean
the oxygen is less likely to bind (caused by increase in CO2 and 2,3-DPG concentration)
what can increase oxygen delivery to tissues
increasing ventilation, cardiac output, capillary diameter, Hb content or number of RBCs
what is the main buffer which controls blood pH
bicarbonate-carbonic acid system (CO2+H2O --> H2CO3 --> H+ + HCO3-)
describe carbon dioxides impact of acidity of blood
CO2 is more soluble in blood than O2 and N2 and is carried in RBCs as carbonic acid this can dissociate into H+ and bicarbonate
what role do lungs play in maintaining body pH levels
lungs are able to eliminate CO2 (acid)
what is the relationship between blood pH and ventilation
inversely proportional (as pH increases, ventilation decreases in order to conserve CO2)
what detects pH changes in the body?
chemoreceptors near aorta detect pH changes and cause respiratory rate to change accordingly
describe the movement of O2 and CO2 between tissues and blood
movement is based on partial pressures; there is a higher concentration of oxygen in blood, so it moves to tissues, whereas CO2 get removed from tissues
What causes Hb affinity for O2 to decrease near tissues
1. Increased CO2 concentration (dec. binding affinity by making the environment more acidic)2. presence of H+
which is more acidic, venous or arterial blood pH?
venous
what is the mechanism of chemoreceptors?
activate afferent nerves - communicate with medullary respiratory neurons