chapter 7

What is a spirometer? Describe and define the lung volumes measured using spirometry.

A spirometer is a tool used to measure volumes of inspired and expired air, which shows the changes in lung volume. The lung volumes measured include tidal volume, the amount of air that enters and leaves the lungs with one breath, vital capacity, the greatest amount of air that can be expired after maximum inspiration, and residual volume, the remaining amount of air in the lungs after a maximal expiration.

EC

expiratory capacity the amount maximal amount of air which can be expired

ERV

expiratory reserve volume - difference between tidal volume and maximal expiratory volume

FER

forced expiratory ratios

FEV

forced expiratory volume the portion of FVC exhaled in a given time unit. measures how quickly full lungs can be emptied

FVC

forced vital capacity - the volume of a maximal exhale (after a maximal inhale)

IC

inspiratory capacity the amount of maximal amount of air which can be inspired

IRV

inspiratory reserve volume difference between tidal volume and maximal inspiratory volume

expiration

passive process involving relaxation of the inspiratory muscles and elastic recoil of the lung tissue

PEF

peak expiratory flow maximal expiratory flow rate achieved and this occurs very early int he forced expiration

pulmonary diffusion

the process by which gases are exchanged across the respiratory membrane in the alveoli to the blood and vice-versa

TV

tidal volume air inspired or expired with a normal relaxed breath

TLC

total lung capacity

VC

vital capacity

How are oxygen and carbon dioxide transported in the blood?

Oxygen and carbon dioxide are transported in the blood when oxygen either combines with hemoglobin or is disolved in plasma, and when carbon dioxide is carried as bicarbonate ions, dissolved in plasma or is bound to hemoglobin.

daltons law

The total pressure in a mixture of gases is equal to the sum of the individual partial pressures

inspiration

active process involving the diaphragm and the external intercostal muscles

Describe and differentiate between external and internal respiration.

External respiration moves gases from outside of the body into the lungs, and then the blood. Internal respiration is the gas exchange between the blood and the tissues. Both being linked through the circulatory system, the two combined described the process of getting oxygen from outside the body to the tissues.

Describe the mechanisms involved in inspiration and expiration.

Inspiration uses intercostal muscles and the diaphragm. The ribs and sternum are moved by the intercostals while the diaphragm contracts, flattening it in the process. Expiration relates to the relaxing of elastic recoil of the lungs. The diaphragm returns to its normal position when relaxed, and as the intercostals relax, the sternum and ribs also return.

How is oxygen unloaded from the arterial blood to the muscle and carbon dioxide removed from the muscle into the venous blood?

Oxygen is transported in the muscle to the mitochondria via myoglobin. The myoglobin then releases oxygen when PO2 is low. An increase in blood flow due to exercise leads to more oxygen being carried to the muscles. Simple diffusion leads to CO2 leaving the muscle cells and entering back into the blood and eventually to the lungs.

Explain the concept of partial pressures of respiratory gases- oxygen, carbon dioxide, and nitrogen. What is the role of gas partial pressures in pulmonary diffusion?

Partial pressure is defined as the individual pressure from each gas in a mixture, referring to the air inhaled in this case. Oxygen is 20.93% of the mixture while CO2 is 0.03% and nitrogen is the most plentiful gas at 79.04%. This creates a pressure gradient that creates gas exchange. Oxygen exchange then takes place where the body needs it most, while CO2 can cross membranes easier than oxygen.

RV

Residual Volume amount of air left in the lungs after maximal expiration

Describe how pulmonary ventilation is regulated. What are the chemical stimuli that control the depth and rate of breathing? How do they control respiration during exercise?

Respiratory centers control motor neurons. This in turn controls the respiratory muscles. Located in the brain stem and used to establish breathing rate and depth, changes in CO2 and H+ levels alter breathing to get rid of excess CO2 and H+. Forceful breathing during exercise means more expiration of CO2 and H+.

What is meant by the arterial-mixed venous oxygen difference? How and why does this change from resting conditions to exercise conditions?

The arterial mixed venous oxygen difference means the difference in oxygen content between the venous and arterial blood. During intense exercise, the active muscle needs more oxygen, so more is brought to them since PO2 is lower than in the arterial blood.

Where in the lung does the exchange of gases with the blood occur? Describe the role of the respiratory membrane.

The exchange of gases with the blood occurs in the respiratory membrane of the lung. It's made up of the alveolar wall, capillary wall and their basement membranes, and creates a pressure gradient that forms gas exchange diffusion.