Module 8 Flashcards
Dynamic lung measurements are good for distinguishing between RESTRICTIVE and OBSTRUCTIVE respiratory problems. Identify a typical disease for each problem?
Restrictive: Fibrosis of the lung; acute respiratory disorder syndrome (ARDS) Obstructive: Asthma or emphysema.
How would a restrictive respiratory disease affect a person’s breathing and more particularly their dynamic lung measurements?
Decrease in lung capacity
How would an obstructive respiratory disease affect a person’s breathing and more particularly their dynamic lung measurements?
Airways narrowed or collapsing on expiration
Explain restrictive lung disease
Restrictive Lung Diseases (Figure. 8.1): Persons with this type of respiratory problem generally have difficulty in getting a full amount of air into their lungs on inspiration. On expiration, there is no airway collapse, so: i) the FEV1sec /FVC ratio (FEV1%) closer to (1.0) ii) but with decreased values for both FEV1sec and FVC
Explain obstructive lung disease
Obstructive Diseases (OD) Persons with this type of respiratory problem generally have difficulty in getting the air out from their lungs on expiration. They are diagnosed by measuring the FEV1sec /FVC ratio (FEV1%).
Fill out the following diagram
At vertebral level T4/T5 the trachea divides into:
left and right primary bronchi
Examine the two primary bronchi (size: diameter & angle to the trachea) and determine which lung are foreign objects more likely to be inhaled into.
Right lung as its primary bronchi into is more vertical and wider than left.
How many secondary bronchi (lobar) are there in each lung?
Right lung: 3 (one to each of the three lobes), Left lung: 2 (one for each to the two lobes)
Define the term Bronchopulmonary segment.
Segment of lung tissue which is served by its own tertiary bronchus, artery/vein and lymphatics
Approximately how many bronchopulmonary segments are in each lung?
10 per lung (some books may say 10 in right and 8 in left)
What is the function of cartilage in the airway?
To hold the airway open.
Tertiary bronchi branch from the secondary bronchi; why are they sometimes called segmental bronchi?
Each tertiary bronchus serves one bronchopulmonary segment.
Fill in the following table
The bronchopulmonary segments are further subdivided into lung lobules served by bronchioles, are these visible to the naked eye?
yes
What is a characteristic of bronchioles?
Absence of cartilage, presence of submucosal ring of smooth muccle. Submucosal glands also absent
If there is no cartilage present in the bronchioles, what holds the airway open?
Smooth muscle
What distinguishes a terminal bronchiole from a respiratory bronchiole?
The respiratory bronchiole has alveoli budding directly off it
What kind of blood supply do the lungs/bronchial tree have?
a DOUBLE blood supply, meaning they have blood entering and leaving by two sets of blood vessels, the pulmonary vessels (arteries and veins) and the bronchial vessels (arteries and veins)
The last part of the conducting portion is known as the:
Terminal bronchiole
What distinguishes a terminal bronchiole from a respiratory bronchiole?
The respiratory bronchiole has alveoli budding directly off it
Fill in the following table
Fill in the following diagram
What are the two types of cells found in the alveolar epithelial layer?
Pneumocyte type I (Alveolar cell type I)- Gas exchange
Pneumocyte type II (Alveolar cell type ii)- Secrete surfactant
Fill in the following diagram
What is the function of the surfactant?
Decrease surface tension
How does surfactant aid expiration?
Prevents alveolar collapse
A third type of cell wanders along alveolar surfaces removing dust, debris & bacteria. These are called:
Alveolar macrophages (Dust cells)
Small alveolar pores connect adjacent alveoli. What is their function?
Equalise pressure between alveoli
Why is only a small percentage of O2 normally carried by blood plasma?
O2 dissolves very poorly in solution.
Another O2 binding protein which is similar to haemoglobin is found in muscle is called:
myoglobin
What is the driving force for the transport of O2 and CO2 across the respiratory membrane?
Partial pressures
How is CO2 normally carried in the blood? What are the relative percentages?
Dissolved, 7%; Bound to haemoglobin, 23%; as the bicarbonate ion, 70%.
When CO2 binds to haemoglobin, what compound is formed?
carboxyhaemoglobin.
Why is COsuch a poisonous substance?
It competes with, and displaces O2 from haemoglobin.
In your graph, what is the physiological significance of: a. the steep portion of the line between 0 and 40 mmHg PO2? What is the %O2 Hb saturation at these PO2 values?
These are the sorts of PO2’s found in metabolizing tissues. The steep relationship between %O2Hb and PO2 facilitates the unloading of O2 from Hb as in this region small falls in PO2 lead to large reduction in the saturation of Hb with O2 leading to greater O2 delivery to the tissues
the plateau portion of the line between 40 and 100 mmHg PO2? What is the %O2 Hb saturation at these PO2 values?
Allows a safety margin for the loading of O2 in the lungs such that if the alveolar PO2 falls to as low as ~70 mmHg the Hb can still leave the lungs with high O2 saturation.
What kind of coniditions facilitate a right shift in O2 dissociation curve and therefore increase in O2 supply to the tissues?
Temperature increase, PCO2 increase and pH decrease.
Skeletal muscles need more oxygen during exercise and this is partly achieved by increased blood flow. What other mechanisms facilitate increased O2 delivery to muscle fibres during exercise?
Lower tissue PO2 –further down the curve for unloading Right shifted curve - decreased pH, increase temp, high PCO2 etc
Sadly, many swimming pool deaths in children are caused by strenuous underwater swimming, post-hyperventilation. Can you offer a physiological explanation for this problem?
Hyperventilation blows of the CO2, thus reduces the stimulus to breathe. Vigorous swimming drops the PO2 so much that the person loses consciousness (person passes out underwater). Breathing is not stimulated because the CO2 remains at a low level; person drowns.
What sensory mechanisms exist in the body to monitor blood gases?
Chemoreceptors
Where are the peripheral chemoreceptors located?
Carotid (arotid sinus) & Aortic (aortic arch) Bodies
Where are the central chemoreceptors located?
In the medulla of the brain, close to the respiratory centres
What specific chemicals do the peripheral chemoreceptors monitor?
H + , CO2 and O2.
What body fluid are the peripheral chemoreceptors bathed by?
Arterial blood
What specific chemicals do the central chemoreceptors monitor?
H + derived from blood PCO2
What body fluid are the central chemoreceptors bathed by?
CSF
Why are the central chemoreceptors so sensitive to blood PCO2 levels?
CSF contains no buffers to contain any change in pH. As soon as CO2 diffuses into the CSF, it is quickly converted to H+ and stimulates the chemoreceptors.
Why are peripheral chemoreceptors not very sensitive to PO2 levels?
They are monitoring arterial blood which normally has a PO2 >98 mmHg
When do peripheral chemoreceptors respond to changing PO2 levels to stimulate respiration?
When the PO2 falls below 60 mmHg, they stimulate the respiratory centres to increase respiration rate; this is called hypoxic drive.
