Final Flashcards
In what situation can we make the intraplural pressure positive?
- forced expiration, Use abdominals or internal intercostals
- COUGHING
At what week does the respiratory diverticulum (lung bud) appear as an outgrowth from the ventral wall of the foregut?
week 4
The appearance and location of the lung bud are dependent upon an increase in what?
retinoic acid
Increase in retinoic acid causes upregulation of _________, expressed in the endoderm of the gut tube at the site of the respiratory diverticulum?
TBX4
The epithelium of the internal lining of the larynx, trachea, and bronchi, as well as that of the lungs is entirely of what origin?
Endoderm
The cartilaginous, muscular, and connective tissue components of the trachea and lungs are derived from _________, which surrounds the foregut?
Splanchnic mesoderm
What separates the respiratory diverticulum from the foregut when it expands caudally?
2 tracheoesophageal ridges
What muscles are used for inspiration during certain circumstances (e.g. exercise) besides the diaphragm and external intercostals?
- Scalene: raise 1st and 2nd ribs
- Sternomastoids: raise sternum
- Some muscles in head and neck
What is an abnormality in the partitioning of the esophagus called?
esophageal atresia with or without tracheoesophageal fistulas (TEFs)
What abnormality with amniotic fluid often detected by ultrasound can be an indicator for a TEF?
Polyhydramnios because the amniotic fluid when swallowed does not pass to the stomach and intestines
How many secondary bronchi develop in the right and left lungs respectively?
3, 2
How many tertiary (segmental) bronchi develop in the right and left lung respectively?
10, 8
At what stage of development are sufficient numbers of mature alveolar sacs and capillaries present to guarantee adequate gas exchange to allow survival?
7 months
What do type II alveolar cells do?
produce surfactant
Explain the roles of surfactant and macrophages in preparation for labor and delivery.
- surfactant enters amniotic fluid and acts on macrophages.
- These macrophages migrate across the chorion to the uterus to produce immune proteins including IL-1beta
- This leads to increased production of prostaglandins that cause uterine contractions
What is the cause of respiratory distress syndrome?
- insufficient surfactant
- -Surfactant decreases the risk of respiratory distress syndrome because it prevents alveolar collapse by keeping the air-water (blood) surface membrane tension low
how is respiratory distress syndrome treated?
- Treat the preterm babies with artificial surfactants
- Treat mothers with premature labor with glucocorticoids to stimulate surfactant production
Why does the fetus engage in breathing movements in utero?
- This is important for stimulation of lung development
- This conditions the respiratory muscles
How do ectopic lung buds form?
It is believed that these are formed from additions respiratory buds of the foregut that develop independent of the main respiratory system
What is the term that describes the difference between the pressure volume curves for inspiration and expiration?
hysteresis
What causes hysteresis?
Surfactant
-size of alveoli and position of surfactant causes molecules to not follow the same path
In a normal person what is the ratio of FEV1;FVC?
80%
What will the ratio of FEV1:FVC be in a person with obstructive disease (asthma or emphasema)?
70% or less
What will the ratio of FEV1:FVC be in a person with a restrictive disease (interstitial fibrosis)?
> 90%
What respiratory center is believed to be the site which generates the timing (frequency) of the respiratory rhythm?
Pre-Botzinger complex
Failure to turn inspiration off
Apneusis
What respiratory group tells inspiration when to turn off?
Pontine respiratory group (PRG)
What respiratory group mostly tells the phrenic nerve what to do and is mostly involved in inspiration?
Dorsal respiratory group
What respiratory group is involved in inspiration and not only helps control the phrenic nerve but also controls the accessory muscles?
Rostral part of Ventral Respiratory Group (VRG)
What respiratory group provides premotor to the upper airway and other muscles of expiration?
Caudal regions of the ventral respiratory group
Absence of respiratory effort (no inspiration)
Apnea
What causes Apneusis?
Pontine damage
what causes Apnea?
medullary or spinal damage
What 3 factors increase the firing of a chemoreceptor?
- INCREASE in CO2
- DECREASE in O2
- INCREASE in H+
Explain how chemoreceptors on the ventral portion of the medulla are indirectly sensitive to CO2 in the blood?
- CO2 crosses BBB
- reacts with water via carbonic anhydrase
- creates H+ and HCO3 in CSF
- Chemoreceptors respond to the CSF H+
- IMPORTANT NOTE!! arterial CO2 is activating these but indirectly
What neurotransmitter do the peripheral chemoreceptors use?
Dopamine
Which chemoreceptors are faster? Peripheral or central?
Peripheral
Which chemoreceptors are responsible for respiratory drive?
Central
Fibers of the pulmonary stretch receptors travel to the brain via what?
Vagus nerve
What is the effect of increased firing rate of pulmonary stretch receptors?
Turn off inspiration and prolongation of expiration
The slowly adapting pulmonary stretch receptors are important for controlling respiration in what?
- infants
- Adults during exercise
What are the rapidly adapting pulmonary stretch receptor sensitive to?
Irritation; foreign bodies in the airway; stretch
What is the effect of increased firing of the rapidly adapting pulmonary stretch receptors?
Cough
What are J receptors sensitive to and where are they located?
Pulmonary edema; Near blood vessels of alveoli
What is the effect of increased firing of a J receptor?
Cough or tachypnea (rapid shallow breathing)
How do the kidneys compensate for a respiratory acidosis and what are the results of this compensation?
- secrete H+ and reabsorb HCO3
- Result: increases plasma bicaronate levels
What do the kidneys do to compensate for respiratory alkalosis and what are the results?
- reabsorbing H+ and excreting HCO3
- Result: decreases in plasma bicarbonate levels
What is the expected bicarbonate equation for an ACUTE respiratory acidosis?
[HCO3]=24 + ((PaCO2 - 40)/10)
What is the expected bicarbonate equation for a CHRONIC respiratory acidosis?
[HCO3]=24 + 4((PaCO2 - 40)/10)
What is the expected bicarbonate equation for a ACUTE respiratory alkalosis?
[HCO3]=24 - 2((40 - PaCO2)/10)
What is the expected bicarbonate equation for a CHRONIC respiratory alkalosis?
[HCO3]=24 - 5((40 - PaCO2)/10)
What is the equation for decided if the respiratory compensation for a metabolic acidosis is adequate?
expected PaCO2=(1.5[HCO3] + 8) +/- 2
Anion Gap equation
Anion Gap=[Na] - ([Cl] + [HCO3])
What should the number be for a normal anion gap?
= 12
What are the important unmeasured chemicals to remember that make the anion gap greater than 12 in the MUDPILES mnemonic?
D: diabetic ketoacidosis, starvation or alcoholic ketoacidosis
L: lactic acidosis
S: salicylates
What is the equation to see if the respiratory compensation for for metabolic alkalosis is adequate?
change in PaCO2=(.5 to 1) x change in HCO3
Standard chest images obtained in radiagraphs are what view?
PA or lateral
What are the problems with taking a chest radiograph from the AP view?
- More magnification so less sharp
- Patients unable to take deep inspiration so lung less expansion
What are the ABCs in interpretting a chest radiograph?
Airway Breathing, Borders and Bones Circulation and Contours Diaphragm Everything Else
On a chest radiograph, during a full inspiration where should the diaphragm be observed?
- 8th to 10th ribs posteriorly
- 5th to 6th rib anteriorly
How much space in the thorax should the heart normally occupy?
No more than 50% of the width of the thorax
Describe the respiratory epithelium
Pseudostratified ciliated epithelium with goblet cells, supported by a lamina propria with seromucous glands and a rich superficial venous plexus
What warms incoming air?
blood in the venous plexus
What moistens the incoming air?
secretions of the seromucous glands and goblet cells
What do the superior, middle and inferior conchae do?
Create turbulence to help warm and moisten the air
What are the paranasal sinuses lined by?
thin pseudostratified columnar ciliated epithelium with few goblet cells
What is the purpose of the cilia?
beat to remove unwanted materials backwards into pharynx to be removed via GI system
Secretory cell at the end of the conducting airway in the terminal bronchioles
Clara cells
What is in Mucus?
- Mucins
- antimicrobial molecules (defensins, lysozyme, and IgA)
- Immunomodulatory molecules (secretoblobin and cytokines)
- Protective molecules (trefoil proteins and heregulin)
- Abnormally thick mucus by GI and respiratory glands
- Inherited mutations of CFTR which results in defective transport of Cl- and increased Na+ absorption
- bacterial infections
- cough, purulent secretions, and dyspnea
Cystic Fibrosis
Cells that rest on the basal lamina, but do not extend to the lumen and act as stem cells to give rise to ciliated epithelium and may give rise to goblet cells
Basal cells
Cells that rest on the basal lamina but do not extend to the lumen which produce a variety of peptide hormones (serotonin, somatostatin, calcitonin, ADH, ACTH), may give rise to TUMORS
Neuroendocrine cells (cells of kulchitsky)
Smoker’s epithelium changes from pseudostratified ciliated columnar to what? and why? What are the consequences of this change?
stratified squamous
- thicker and more protective
- Not particularly good at picking up inhaled particulate matter
- not a good mucous layer and no cilia
- Increases goblet cells because these are trying to compensate
What holds the trachea open?
C shapes rings of hyaline cartilage
What is found on the posterior part of the trachea and why?
- Fibroelastic ligament - prevents overdistension of the lumen
- trachealis muscle - smooth muscle that results in narrowing during cough reflex - small diamter increases velocity of expired air
Once the trachea bifurcates at the carina into the left and right main bronchi, how does it’s structure change?
- C-shaped cartilage breaks down into cartilage plates and smooth muscle bundles shift between the mucosa and the cartilage plates
- Aggregates of lymphoid tissue are observed in the wall of intrapulmonary bronchi, known as BALT (bronchial associated lymphoid tissue)
As bronchi turn to bronchioles, describe the histological changes?
- epithelium reduces thickness
- number of goblet cells reduced-replaced by clara cells in terminal bronchioles
- epithelium becomes simple ciliated columnar
- Lamina propria becomes dominated by a spiraling layer of muscularis mucosa
- cartilage and glands disappear
- reduction of diameter
What is the difference between goblet and clara cells?
Clara cells produce a less viscous secretion
A terminal bronchiole and the associated regions of pulmonary tissues that it supplies?
pulmonary lobule
When u transition from a terminal bronchiole to a respiratory bronchiole, what begins to appear?
alveoli - gas exchange can occur
Club (clara cells) produce what?
surfactant that differs from that produced by type II alveolar cells
After airway injury, clara or club cells can do what?
proliferate and migrate to replenish alveolar epithelial cells - known as alveolar bronchiolization
Club or clara cells can engulf airborne toxins and break them down via what?
cytochrome P-450 enzymes (CYP4B1) present in their endoplasmic reticulum
Resistance=?
(9nL)/r^4
n: viscosity
L: length of tube
r: radius of tube
J=?
[SA x D x (P1-P2)]/distance
J: diffusion rate in ml/min
D: diffusion coefficient for each gas
(P1-P2): pressure gradient across alveolar membrane
SA: surface are available for diffusion
distance: diffusion distance (thickness of alveolar barrier)
What is the normal resting value of J (how much gas is exchanged every minute) for oxygen?
250 ml/min
What is the normal resting value of J (how much gas is exchanged every minute) for CO2?
200 ml/min
Describe the interalveolar septa?
two simple squamous epithelial layers with the interstitium (nonfenestrated cappillaries embedded in an elastic connective tissue) between them
Type I alveolar cells represent ______ of the alveolar epithelial cell population and cover _______ of the alveolar surface?
- 40%
- 90%
Type II alveolar cells cover _____ of the cells and _____ of the alveolar surface?
- 60%
- 10%
Cells in interstitium that clean up debris and can also phagocytize RBC’s when they get into the lungs due to heart failure?
Alveolar macrophages (dust cells)
During rest, how much blood is in pulmonary capillaries?
70 ml
During exercise, how much blood can be in pulmonary capillaries?
up to 200 ml
Elastase can destroy elastic tissue by being released by neutophils present in the alveolar lumen. What neutralizes elastase?
Serum alpha1-antitrypsin (serum trypsin inhibitor)
The loss of elastic fibers due to elastase is called what?
Emphysema
A form of pulmonary edema that causes acute respiratory failure from increased permeability of the alveolocapillary membrane
Acute respiratory distress syndrome (ARDS)
Collagen being inappropriately deposited in the interstitium of the lungs
Pulmonary interstitial fibrosis
What is the diffusion capacity of the lung for oxygen in a normal individual at rest?
21 O2/min/mm Hg
DLO2=?
1.23 x DLCO
Diffusion capacity of oxygen is determined by measuring what?
The diffusion capacity of CARBON MONOXIDE (CO)
What is the diffusion capacity of the lung for Carbon Dioxide in a normal individual at rest?
~400 ml CO2/min/mm Hg
What stage of lung development does a fetus become viable due to formation of respiratory bronchioles and primitive alveoli and what weeks does this occur?
Canalicular stage (17-26 weeks) -cutoff is 24 weeks
Laplace’s Law:
Pressure=2T/r
T: surface tension
r: radius
Above what Pressure of O2, on the normal Hb curve is the Hb more than 90% saturated?
60 mmHg
If the A-a gradient is greater than this, there is a problem with the alveoli.
20 mm Hg
What causes ectopic endodermal budding, tracheoesophageal fistulas, and ectopic TBX4 expression?
Misexpression of FGF10
Incomplete expansion or collapse of parts of or a whole lung?
Atelectasis
Inadequate oxygen available for use by the tissues
hypoxia
Total absence of oxygen being delivered to the tissue
Anoxia
Low oxygen content in the blood
hypoxemia
Form of hypoxia where PaO2 is below normal. Also name causes
Hypoxic hypoxia
-Lung diseases with diffusion impairments such as emphysema or fibrosis
Form of hypoxia where the lungs are perfectly normal but the oxygen carrying capacity of blood has been reduced. Also name the causes
-Anemic hypoxia
Causes: Carbon monoxide,
Form of hypoxia where lungs are working fine and blood can carry sufficient oxygen but the tissue is not receiving sufficient oxygen because the heart cannot pump the blood to the tissue (or arteries are blocked). Give causes
Circulatory hypoxia
-Causes: sickle cell anemia
Form of hypoxia where there is no problem getting the oxygen to the tissues however the tissue is unable to use the oxygen. Give causes
Histotoxic hypoxia
-Causes: cyanide
reduced FEF 25-75% is indicative of what?
early small airway obstruction