IB Biology: Gas Exchange

ventilation

movement of air in and out of the lungs

Pneumocytes

or Alveolar cells are the cells that line the alveoli and compare of the majority of the inner surface of the lungs.

type I pneumocytes

-involved in the process of gas exchange between the alveoli and the capillaries

-It is squamous in shape and extremely thin- it minimises diffusion distance for respiratory gases

type II pneumocytes

responsible for the secretion of pulmonary surfactant, which reduces surface tension in the alveoli

inhalation conditions

external intercostals and diaphragm contract; thoracic cavity expands and pressure within it decreases

exhalation conditions

external intercostals and diaphragm relax; internal intercostals may contract; thoracic cavity descreases in volume and pressure within it increases

emphysema

a condition in which the air sacs of the lungs are damaged and enlarged, causing difficulty in breathing, especially exhaling

alveoli

tiny sacs of lung tissue specialized for the movement of gases between air and blood

trachea

a large membranous tube reinforced by rings of cartilage, extending from the larynx to the bronchial tubes and conveying air to and from the lungs; the windpipe.

bronchi

two short branches located at the lower end of the trachea that carry air into the lungs.

bronchioles

Airways in the lungs that lead from the bronchi to the alveoli.

main cause of lung cancer

smoking

spirometer

An instrument for measuring the air entering and leaving the lungs.

tidal volume

Amount of air that moves in and out of the lungs during a normal breath

minute volume (pulmonary ventilation rate)

breaths per minute x tidal volume

gas exchange

the process of obtaining oxygen from the environment and releasing carbon dioxide

cell respiration

the process in cells in which oxygen is used to release stored energy by breaking down sugar molecules

surfactant

chemical produced in the lungs to maintain the surface tension of the alveoli and keep them from collapsing

negative pressure breathing

A breathing system in which air is pulled into the lungs when the lung volume is expanded.

diaphragm

a dome-shaped, muscular partition separating the thorax from the abdomen in mammals. It plays a major role in breathing, as its contraction increases the volume of the thorax and so inflates the lungs.

intercostal muscles

Muscles which move the rib cage during breathing

residual volume

Amount of air remaining in the lungs after a forced exhalation

vital capacity

The total volume of air that can be exhaled after maximal inhalation.

expiratory reserve volume

Amount of air that can be forcefully exhaled after a normal tidal volume exhalation

inspiratory reserve volume

Amount of air that can be forcefully inhaled after a normal tidal volume inhalation

total lung capacity

vital capacity + residual volume

inspiratory capacity

tidal volume + inspiratory reserve volume

functional reserve capacity

At the end of a normal expiration, the volume of air remaining in the lungs

tidal volume

Amount of air that moves in and out of the lungs during a normal breath