Respiratory System Flashcards
Approximately 1L of oxygen is transported to cells each minute. How is most of the body’s transported?
bound to Hgb
What usually has a higher pH, venous or arterial blood?
Arterial blood
What are the conducting airways of the lower airway?
Larynx
Trachea
Segmental bronchi
Non-respiratory bronchioles
(no gas exchange occurs here)
What are the respiratory units of the lower airway?
Respiratory bronchioles
Alveolar ducts
(where gas exchange occurs)
What do Type I alveolar cells do?
Provide structure to the alveoli
What do Type II alveolar cells do?
Produce surfactant
What is surfactant?
A phospholipid essential to maintain alveolar patency. Decrease surface tension and facilitate gas exchange.
What do the narrow airways in pediatric patients predispose them to?
Increased risk for obstruction and increased resistance to air flow.
At birth newborns have about _____ of alveoli
1/6 to 1/8 the amount an adult has (which is 300mil)
At what age are alveoli matured and increased in size and number by?
8yrs
What happens to the alveoli in elderly patients?
Reduction of alveolar units
What are the two suppliers of blood supply to the lungs?
Bronchial artery system
Pulmonary artery system (vast network)
What is a normal pulmonary pressure?
22-25/8 mmHg
What are the functional components of the resp system? (4)
- Neurochemical control of ventilation
- Mechanics of breathing
- Gas transport
- Control of the pulmonary circulation
Area of neural control of ventilation is located in the:
Medulla and pon (aka resp center)
Which population has the most mucous producing glands?
Pediatric
What stimulates the muscles of inspiration?
Dorsal respiratory group of neurons
How do efferent nerve impulses travel from the brainstem to the diaphragm to stimulate muscle contraction (inspiration)?
via the phrenic nerve
What controls airway lumen diameter?
The ANS:
Parasympathetic: constriction
Sympathetic: dilation
What do central chemoreceptors respond to?
CO2 and pH (H+ conc)
CO2 crosses BBB and stimulates respiration
What do peripheral chemoreceptors respond to?
Decrease in O2 concentration and decreased pH
The pons apneustic center:
Stimulates/prolongs inspiration
Pattern of respiration
What does the pneumotaxic center of the pons do?
Influences rate of respiration
Inhibits the inspiration (effectively ending it)
How do the baroreceptors in the aortic arch and carotid bodies affect respiration?
When an increased BP is sensed, respiration is decreased
How do proprioreceptors in muscles affect respiration?
Respond to body movement
What are the main muscles of inspiration?
External intercostals
Diaphragm
What are the accessory muscles and when are they used?
Scalenus muscles
Sternocleidomastoid muscles
Used when main muscles are inadequate
What happens when the diaphragm contracts?
It flattens downward, increasing the volume of the thoracic cavity, and creates a negative pressure that draws gas into the lungs through the upper airways and trachea.
What does contraction of the external intercostals do?
Elevates the anterior portion of the ribs. This increases the volume of the thoracic cavity by increasing its front-to-back (anteroposterior [AP]) diameter
When are accessory muscles of expiration used?
High minute ventilation, during coughing, or when airway obstruction is present
How do the lungs create a small amount of negative intrapleural pressure?
The chest wall likes to expand out and the lungs recoil (elastic recoil)- this create negative pressure
Airway resistance is dependent on:
Length of tube Radius size Density Viscosity Velocity of gas
What are the 3 types of deadspace?
- Anatomic- conducting airways
- Alveolar- ventilated but under-perfused (wasted ventilation)
- Physiologic- anatomic and alveolar
What are the 4 major steps of gas transport?
- Ventilation of the lungs
- Diffusion of oxygen from the alveoli into the capillary blood
- Perfusion of systemic capillaries with oxygenated blood
- Diffusion of oxygen from systemic capillaries into the cells
What is a normal tidal volume?
500ml (normal breath)
What is ventilation?
The process of moving air into the lungs and distributing it to the gas exchange units for maintenance of oxygenation and removal of CO2
What is a major compensatory mechanism in many pulmonary diseases/disorders that impair gas exchange?
Elevated Hgb
Why is PaO2 important?
It is the major driving pressure that causes O2 to move from the plasma into the RBC and bind to Hgb
How is CO2 transported?
- Dissolved in plasma
- Carbamino compounds
- Bicarb (60%)
A shift to the Right of the oxyhemoglobin curve:
Decreases O2 affinity; aids in the release of O2 from blood to tissue
ex- acidosis, hyperthermia
A shift to the Left of the oxyhemoglobin curve:
Increases O2 affinity; tighter bonding of O2 to hemoglobin. Helps loading of O2 in the lungs but impairs delivery to tissues.
ex- alkalosis, hypothermia
What is the difference between hypoxemia and hypoxia?
Hypoxemia is deficient levels of blood oxygen and hypoxia is a decrease in tissue oxygenation
What is hypoxic hypoxia?
Decreased PaO2 despite normal O2 carrying capacity
ex- altitude, hypoventilation, airway obstruction
Give O2
What is anemic hypoxia?
Decreased O2 carrying capacity.
ex- any d/o with low Hgb