8. Respiratory System Flashcards
Anatomy
Anatomy
What are Alveoli?
Alveoli - small, thin-walled sacs that have capillary beds in their walls; site of gas molecule (O2 & CO2) exchange between air and blood; there are millions of alveoli
Cartilage and Smooth Muscle
cartilage provides structural support and flexibility to various body parts
smooth muscle is responsible for involuntary movements in organs like the digestive tract and blood vessels.
what is dead space
no air exchange taking place but air is still being breathed in
What is the Respiratory membrane?
The main function of the respiratory membrane is to enable the exchange of oxygen and carbon dioxide between the air in the lungs and the blood in the pulmonary capillaries.
- average thickness is 0.6 micrometers.
- Very thin – optimized for diffusion
- very large surface area
- 70 square meters in the normal adult - size of one side of a tennis court.
What is Pulmonary ventilation?
- Pulmonary ventilation is the movement of air into and out of the lungs.
- Molecules move from areas of high pressure to areas of low pressure.
- Boyle’s Law - the pressure of a gas is
inversely proportional to its volume.
What is Boyle’s Law?
the pressure of a gas is inversely proportional to its volume.
Why does air move into and out of the lungs?
- The movement of air into and out of the lungs results from a pressure difference between the pulmonary air and the atmosphere.
- Compliance – the amount of volume
change in the lung for a given change in alveolar pressure.
How does the diaphragm work?
Muscles of Inspirations vs Expiration
What is Inspiration?
Inspiration - active process
– diaphragm descends and external intercostal muscles contract thus increasing the volume of the thoracic cavity
– decreased pressure in thoracic cavity causing a one or two mm Hg drop in intra-alveolar pressure at rest compared to the outside atmospheric pressure
- can produce a negative pressure as great
as -30 mm Hg below atmospheric pressure within the alveoli when working their hardest
– air molecules move through the
respiratory tubes into the lungs from
the atmosphere following the pressure
gradient.
What is Expiration?
Expiration – passive process at rest
– diaphragm and external intercostal muscles relax thus decreasing the volume of the thoracic cavity
—> the pressure in the thoracic cavity increases above atmospheric pressure
—> air molecules move out of the
lung following the pressure gradient.
Expiration during Exercise?
Expiration – active process during exercise
– Secondary muscles, such as abdominal muscles and internal intercostals become involved in exercise.
– Forced expiration can produce intra-alveolar pressure as great as +50 mm Hg above atmospheric pressure
mouth breathing tends to replace nasal breathing
During exercise, mouth breathing tends to replace nasal breathing - less resistance to airflow.
* Air that enters the respiratory passages via either the nose or the mouth is quickly saturated with water vapor and warmed to body temperature, 37 degrees centigrade, even under conditions when very cold air is inspired.
What is Tidal volume?
Tidal volume (VT) is the amount of air that is breathed in or out during a normal, quiet breath.
– 500 ml per inspiration or expiration at rest
What is Expiratory reserve volume (ERV)?
Expiratory reserve volume (ERV) is the maximal volume that can be exhaled from the resting end-expiratory position.
– approximately 25% of vital capacity (VC) at rest
What is Inspiratory capacity (IC)?
Inspiratory capacity (IC) is the maximal volume of gas that can be inspired from the resting end-expiratory position.
– approximately 75% of vital capacity (VC) at rest
What is Vital capacity (VC)?
Vital capacity (VC) is the greatest volume of gas that can be expelled by voluntary effort after maximal inspiration.
– The vital capacity is the sum of the inspiratory capacity and the expiratory reserve volume.
What is Residual Volume?
Residual volume (RV) is the volume of gas remaining in the lungs after forced expiration.
What is Functional residual capacity (FRC)?
Functional residual capacity (FRC) is the volume of gas remaining in the lungs at the end of a quiet exhalation.
– It is composed of the expiratory reserve volume plus the residual volume
What is Total lung capacity?
Total lung capacity = vital capacity plus residual volume
What is Forced vital capacity (FVC)?
The forced vital capacity (FVC) maneuver is one in which the subject is instructed to expire as hard and as fast as possible for four seconds.
What is Forced expiratory volume in one second (FEV1.0)
Forced expiratory volume in one second (FEV1.0) is the volume of air expired during the first one second of a forced vital capacity manoeuvre.
Ventilation During Incremental Exercise
- During exercise, minute ventilation increases linearly with increasing exercise intensity (oxygen consumption)
- until approximately
- 50-60% of VO2 max. in untrained subjects
- 75-80% of VO2 max. in endurance athletes.
- Ventilatory threshold –
- the point at which minute ventilation
increases disproportionately with oxygen consumption during graded exercise.
Obstructive disorders
Restrictive disorders
