Respiratory system Flashcards
What does the respiratory system consist of?
- Lungs
- Bronchi
- Larynx
- Pharynx
- trachea
- Nose
Describe what the trachea branches into…
- Branches into bronchi (primary, secondary, and tertiary)
- Then into terminal and respiratory bronchioles
- Then alveolar ducts
- Lastly to alveoli
What happens with branching?
With branching, supportive cartilage is gradually replaced by smooth muscle
What function does smooth muscle serve? And what are the effects?
Contraction and relaxation of the smooth muscle constricts or dilates the bronchioles which effects airway resistance
What are the results of airway dilation during exercise?
dilation –> think getting bigger —> when you give birth
- Reduces airway resistance making the flow of air easier
What are the results of airways that are overly constricted during an asthma attack?
Makes breathing difficult
What are conducting airways?
Conducting airways leads inspired air to the alveoli, but is not involved in gas exchange
What is the average volume of anatomic dead space ?
150 ml
Why is conducting airways called atomic dead space?
Because they are not involved in the exchange of gases
What does VD stand for
anatomic dead space
Alveoli:
- small, thin-walled sacs that have capillary beds in their walls
- site of gas molecule exchange (O2 and CO2) between air and blood
- There are millions of alveoli
Respiratory membrane:
- Separates the air molecules in the alveoli from the blood in the capillaries
O2 entering the bloodstream and CO2 leaving
- Average thickness of 0.6 micrometers, very thin optimized for diffusion, very large surface area (70 square meters…size of a tennis court)
What do lungs contain?
- conducting airways
- alveoli
- blood vessels
- elastic tissue
Mechanisms for breathing:
- Pulmonary ventilation is the movement of air into and out of the lung
- this results from a pressure difference between the pulmonary air and atmosphere
- molecules move from an area of high pressure to areas of low pressure
Boyles law
The pressure of a gas is inversely propotional to its volume
Compliance
The amount of volume change for a given change in alveolar pressure
Describe the process of inspiration
- diaphragm descends and intercostal muscles contract which increases the volume of the thoracic cavity.
- The decreased pressure in the thoracic cavity causes 1-2 mm Hg drop in intra-alveolar pressure at rest compared to the outside atmospheric pressure
- air molecules move through the respiratory tubes into the lungs from the atmosphere following the pressure gradient
What happens when inspiratory muscles work their hardest?
they can produce a negative pressure up to -30 mm Hg below atmospheric pressure within the alveoli
Describe the process of expiration (passive process)
- Diaphragm and intercostal muscles rest thus decreasing the volume of the thoracic cavity
- Therefore, the pressure of the thoracic caivity increases above atmospheric pressure
- air molecules move out of lung following pressure gradient
Expiration (active process during exercise)
- Secondary muscles such as abdominal muscles and intercostal muscles become involved in exercise
- Forced expiration can produce intra-alveolar pressure as great as +50 mm Hg above atmospheric pressure
What happens during exercise
Nose breathing tends to turn into mouth breathing which results in less resistance to airflow
Vital capacity (VC)
the greatest volume of gas that can be expelled by voluntary effort after maximal inspiration
Inspiratory capacity (IC)
the maximal volume of gas that can be inspired from the resting end-expiratory position
(approx 75% of vital capacity at rest)
Expiratory reserve volume (ERV)
the maximal volume that can be exhaled from the resting end-expiratory position
(approx 25% of vital capacity at rest)
What gives the sum of vital capacity
inspiratory capacity + expiratory reserve volume
Functional residual capacity (FRC)
the volume of gas remaining in the lungs at the end of a quiet expiration
What is the sum of the functional residual capacity
expiratory reserve volume + residual volume
Residual volume
the volume of gas remaining in the lungs after forced expiration
Total lung capacity
the volume of gas in the lungs at the time of maximal inspiration
inspiratory capacity + expiratory reserve volume + residual volume
Tidal volume (Vt)
the volume of gas inspired or expired with each breath at rest or during any stated activity
What is the breathing frequency? (Fr)
12-16 breaths per minute
- during maximal aerobic exercise breathing frequency can increase up to 60 breaths per minute and tidal volume can increase up to 50% of vital capacity
Minute ventilation (Ve)
the volume of gas that’s either inspired or expired (but not both) per minute
Tidal volume x number of breaths
Forced vital capacity (FVC)
when the subject is instructed the expire as fast and hard as possible for 4 seconds
Forced expiration volume in one second (FEV1)
the volume of air expired during the first 1 second of a forced vital capacity manoeuvre
Alveolar ventilation
- the volume of air that reaches the alveoli per minute
- this is the only air that participates in gas exchange with the blood
Va: Fr x (Tidal volume - anatomical dead space)
Most volume capacities _________ when a person lies down and _________ when standing. EXPLAIN WHY!!!
decrease, increase
1. abdominal contents push up against diaphragm
- There is an increase in the intrapulmonay blood volume in the horizontal position which decreases the space available for pulmonary air
Pulmonary function test norms are based on….
sex, age, and height
Problems with pulmonary function norms
- don’t consider the size of the subject, particularly chest size
- better to use sitting height than standing height
Ventilation during incremental exercise
Minute ventilation increases linearly with increased exercise intensity and
oxygen uptake until about 50-60% VO2 max in untrained subjects and about 75-80% of VO2 max in endurance athletes
Ventilation threshold
the point which minute ventilation increases dispraportionally with oxygen consumption during graded exercise
Name the two chronic respiratory dysfunctions
- obstructive disorders
- restrictive disorders
Obstructive disorders
blockage or narrowing of the airway causing increased airway resistance (asthma, bronchitis, emphysema)
- bronchiolar obstruction can result from inflammation and edema, smooth muscle constriction, and bronchiolar secretion
- more difficult to move air in and out which decreases FEV1
- FEV1/VC decreases much less than 80% and decreased MBC
Restrictive disorder
- damage to the lung tissue
- loss of elasticity and compliance limiting the expansion of the lung
- all lung volumes are reduced (VC, RV, FRC, TLC because lung tissue is stiff and can’t be expanded
- FEV1 and MBC decrease
- FEV1/VC ratio is 90% or greater
maximum breating capacity
maximum volume of air that can be breathed during maximum effort
Diffusing capacity can be affected by
- thickness of the respiratory membrane
- the number of red blood cells or hemoglobin
- the SA of the respiratory membrane available for diffusion (diffusion capacity is decreased for emphysema)
