Misc. Flashcards
What is the CFTR channel responsible for?
Moving Chloride ions outside of cells in the lungs and other organs.
What are the consequences of a mutation in the CFTR gene?
CFTR is unable to move Chloride ions out of cells, resulting in buildup of sticky mucous on the outside of cells.
What are the characteristics of Type 1 hypersensitivity?
Allergy
Immediate
Th2 cells promote IgE secretion (via IL-4)
Mast cell degranulation (bind FcER on IgE)
May be local (common) or systemic (rare: anaphylaxis)
e.g. Atopy
Two Phases: immediate = mast cell degranulation; delayed: cytokine and chemokine release
What are the characteristics of Type 2 hypersensitivity?
Antibody mediated
IgM and IgG against cell-bound or extracellular matrix antigen.
e.g. Graves Disease.
What are the characteristics of Type 3 hypersensitivity
IgM and IgG immune complex deposition
e.g. SLE
What are the characteristics of Type 4 hypersensitivity?
Delayed type hypersensitivity
CD4 mediated
e.g. Coeliac disease, TB
What are the characteristics of allergens (ingested vs. inhaled)
Inhaled: highly soluble proteins carried by small proteins
Ingested: slowly degraded molecules, very stable.
What occurs in the “sensitisation” phase of Type 1 Hypersensitivity?
Th2 cell differentiation
What happens in Coeliac disease and what kind of hypersensitivity is it?
Type 4/DTH
T-cells recognise Gliadin Peptides (rich in glutamine and proline)
Transglutaminase enables HLA-DQ2 to bind Gliadin
In what forms is CO2 transported in the blood? in what proportions?
10% dissolved
30% attached to proteins
60% bicarbonate
What enzyme is responsible for the formation of Bicarbonate in the blood?
Carbonic anhydrase
Out of CO2 and O2, which diffuses more quickly across the A-C membrane?
CO2 diffuses 20 times faster than O2.
In general, what is the reason for increased PACO2?
Inadequate alveolar ventilation:
What is the relationship between Arterial CO2 concentration and Alveolar ventilation?
Pa(CO2) is proportional to the inverse of Alveolar ventilation.
Which nerve supplies the diaphragm?
Phrenic
What do the External intercostal muscles do? Which nerve provides their innervation?
Increase A-P thorax diameter
Which muscles are involved in active expiration?
Abdominal muscles
Internal intercostals
The Work of Breathing is the sum of which two forces?
Resistive + Elastic
What is meant by the Resistive forces of breathing?
The resistance to air-flow by the walls of the tube through which it is travelling (i.e. increased resistance with decreased diameter)
What is meant by the Elastic forces of breathing?
Force required to expand the lungs against the elastic forces generated by the surface tension in alveoli and the lung tissue itself.
What is Compliance?
(Change in volume)/(change in pressure) a way of determining the elastic properties of the lung.
What breathing pattern would you observe in a patient with Airflow obstruction?
Deep, slow breaths
What breathing pattern would you seen in a patient with stiff lungs/reduced compliance?
Rapid, shallow breaths
What do the following stand for? PaO2, PaCO2.
What are their normal values?
Arterial PO2 and PCO2.
Their normal values are 100mmHg and 40mmHg respectively.
Where are central chemoreceptors located?
Ventral surface of medulla
What do central chemoreceptors respond to?
CSF [H+] (i.e. [CO2] of blood)
Where are peripheral chemoreceptors located?
Carotid bodies: bifurcation of common carotid arteries in the neck
Aortic bodies: Around the arch of aorta
What do peripheral chemoreceptors respond to?
Decreased PaO2
Decreased pH
Increased PaCO2
What limits exercise capacity in a healthy person?
Heart-rate
What are two muscles involved in active exhalation?
Sternocleidomastoid + scalene
What is Pulsus Paradoxus?
An increased difference between the blood pressure at inhalation vs. exhalation.
An abnormally large decrease in systolic BP during inhalation.
What are three possible causes of an increased A-a Gradient?
Right to Left Intrapulmonary Shunt (due to fluid filled alveoli)
V/Q Mismatch (due to lung dead space)
Alveolar hypoventilation
What is A-a gradient a measure of?
Efficiency of gas exchange between alveolus and artery.
What is the alveolar gas equation?
PAO2 = PiO2 - PACO2/RQ (approximately)
Use ~150 for room air PiO2 = partial pressure of inspired oxygen
RQ = Respiratory Quotient= Ratio of CO2 production to O2 consumption
What are the characteristics of Respiratory epithelium? (i.e. what type of epithelium? Which cells are involved?)
30% ciliated columnar cells - move mucus Goblet cells (30%) - Secrete mucus Basal (stem) cells (30%) - renew epithelium Brush cells with microvilli (3%) Serous cells (3%) - secretory
How many rings of hyaline cartilage in the trachea?
10-12
What is found int he submucosa of the trachea?
Glandular structures that produce mucous -> glands and connective tissue
What layers make up the Trachea and what are these layers composed of?
Adventitia: cartilage + outer connective tissue
Submucosa: Glands + connective tissue
Mucosa: Lamina propria + epithelium
What are the structural differences between the bronchi and the trachea?
Thinner walls
Cartilage ring breaks down into individual plates in the intrapulmonary bronchi
What are the distinguishing features of bronchioles?
No cartilage
No goblet cells in epithelium
No ciliated columnar cells
Clara cells present
Why will you find ciliated cells further down the respiratory tract than you will find goblet cells?
Because goblet cells produce mucus and cilia are required to move mucus out of the respiratory tract.
What are Clara cells?
Columnar to cuboidal cells with short microvilli.
Present in bronchioles
Secrete surfactant to destroy surface tension.
What is the difference between Terminal and respiratory bronchioles?
Terminal: final level of conducting system. Cuboidal epithelium
Respiratory: Cuboidal to squamous epithelium. Contain some alveoli.
What will you find in the interalveolar septa?
Elastin fibres: pull apart alveoli
Pores: allow air to equilibrate
Type I and II pneumocytes
Intra-alveolar macrophages
What are the characteristics of type I pneumocytes?
Epithelial cells of alveoli
Simple squamous
Tight junctions limit ECF leakage
prominent basal lamina
What are the characteristics of type II pneumocytes?
Cuboidal, chunky, big Short microvilli Lamellar bodies Secrete surfactant more common than Type I (but only 5% of area) Can divide and give rise to Type I or II
What will you find between the lumen of an alveolus and an erythrocyte in the lumen of a pulmonary capillary?
Surfactant - alveolar epithelium - fused basal laminae - endothelium
What drains into the interpleural space? What is the significance of this?
Lymphatics.
Cancer can spread via this route.
What is anaphylaxis caused by?
Complete Mast cell degranulation
What does Histamine acting on H1 cause in an allergic reaction?
Pain and itch
Vascular ‘leak’
Mucous secretion
Bronchospasm