Lecture 17 - Respiratory Physiology # 1 Flashcards
What is the epiglottis’ job?
To cover the trachea during swallowing so choking doesn’t occur
Why is it important for the alveoli to be so thin?
So gas exchange can be as efficient as possible
Which segments of the respiratory system contain cilia?
Trachea, Bronchi, Bronchioles and Some Respiratory Bronchioles
Which structures in the respiratory system contain cartilage?
Trachea, Bronchi (patchy)
Where is pressure lower: intrapleural or intrapulmonary
Intrapleural pressure is lower than intrapulmonary pressure and this is what prevents lungs from collapsing
Where is intrapulmonary pressure referring to?
Inside the lungs
Where does gas exchange occur in the lung’s anatomy?
Beyond the level of bronchioles = respiratory bronchioles, alveolar ducts, alveolar sacs
Is costal breathing normal breathing?
No, we might see costal breathing during dyspnea or when the abdomen is painful
Costal breathing = requires intercostal muscles. AKA shallow breathing.
When is intrapulmonary pressure slightly positive during the respiratory cycle?
On expiration
What pathology may be secondary to hyperventilation?
Respiratory alkalosis
Low blood CO2 levels
What structures of the respiratory system contain smooth muscle?
Trachea, Bronchi, Bronchioles, Respiratory bronchioles (some), alveolar ducts (some)
What is the purpose of the nasal cavity?
Warm and humidify air
What is the purpose of pleural fluid?
To greatly reduce friction between lung and chest wall
What does pliability refer to? Why might this be important?
The ability for the nares to dilate. This is important if an animal needs more air or if they are obligate nose breathers
What happens to f (breathe rate) in a disease state?
Increases (usually)
Define ventilation:
The exchange of gas that is in the airways and alveoli with atmospheric air thus replenishing alveoli with oxygen and removing carbon dioxide.
What is tidal volume? (V T)
Total volume of air brought into the body during one normal breath
includes dead space and alveolar volume
What is the average mL/Kg for Tidal Volume?
~15mL/Kg
Term for: excess and reduced CO2
Hypercapnia or hypocapnia
Tachypnea
Rapid shallow breaths (different from hyperventilation) after exercise
Definition for respiration
Movement of oxygen into the animal and distribution to the tissue along with the movement of carbon dioxide out of the tissues and expelled from the animal
Polypnea
Rapid breathing e.g. panting
not tachypnea which is rapid and shallow
Pleura
Thin membranes adhering body cavities to body walls
Normoventilation
Normal, usual breathing
CO2 levels maintained within the normal range (~40mmHg)
What is the anatomic dead space or conducting zone?
An area where no diffusion or gas exchange occurs
What is mean dead space volume (mL/kg)
~5 mL/Kg
Where (anatomically/at what structures in the airway) would the dead space be found?
Above the level of respiratory bronchioles = trachea, bronchi, bronchiles
Intrapleural pressure during inspiration
-10mmHg
Intrapleural pressure at end of expiration
-5mmHg
What secondary pathology occurs with hypoventilation?
Respiratory acidosis
high blood CO2
What is hypoventilation?
Lower ventilation levels than the patient’s needs
When does hypoventilation occur most often
sedation and anesthesia
Hyperpnea
Increased depth of breathing
Eupnea
Abdominal breathing = normal, quiet respiration
Bradypnea
Slow breathing rate
Alveolar ventilation definition
Volume of gas that actually participates in gas exchange over a period of time
Alveolar ventilation equation
Number of breaths times the difference in tidal volume and dead space
V A = f x (V T- V D)
f = # of breaths, V T = tidal volume, V D = deadspace volume
About how much does the intrapulmonary pressure change by during the respiratory cycle?
~1mmHg
Since pressure equilibrates so rapidly as air moves in and out
About how much does intrapleural pressure vary during the respiratory cycle?
5mmHg
What feature of the trachea ensures it does not collapse?
Cartilaginous rings
How would we calculate expired minute volume?
VE with dot over top
VE = f x VT
If V signifies volume, what does V with a dot over top mean?
This refers to volume over a certain period of time
“f”
Respiratory rate
Number of breaths per minute
During panting respiratory frequency 1. (increases or decreases?) and tidal volume 2. (increases or decreases? so that alveolar ventilation remains constant
- increases
- decreases
How many phases of inspiratory and expiratory during one cycle of breathing for most animals? What about for horses?
1:1
Horses are the exception with 2 phases to inspiration and expiration
Which pleura forms the central part of the thoracic cavity?
Mediastinal pleura
Which pleura adheres to the lungs?
Visceral plerua
During inspiration muscles 1. (contract or relax?), diaphragm 2. (contracts or relaxes?), and ribs move 3. (inwards or outwards)
- Contract
- Contracts
- Outwards
When the lungs expand pressure in the alveoli becomes (negative or positive)?
negative - so air flows in
What brings the chest wall and lungs back to resting positions?
hint: is this an active or passive process?
Elastic recoil
Apnea
Suspension of normal breathing
Hypoxia vs hypoxemia
Hypoxia is a pathological condition where the body or a region is deprived of adequate oxygen. Hypoxemia is artificially low PO2 - you can have hypoxia in the absence of hypoxemia
