Respiratory System Flashcards
What is external respiration?
The exchange of gases between the body and environment - inhalation and exhalation cycle
External respiration provides ________ which is input for energy production and metabolism
oxygen
External respiration eliminates _________ - waste product of metabolism
carbon dioxide
The blood transports oxygen and carbon dioxide between the ________ and ________
lungs
tissues
The exchange of _______ and _________ between blood and tissues by diffusion is gradient dependent
oxygen and carbon dioxide
Where are the lungs located?
In the pleural sac in the rib cage
During inhalation, what happens to the diaphragm and intrapleural space?
Contraction of the diaphragm
Expansion of the interpleural space
Increase in negative pressure
During exhalation, what happens to the diaphragm and the interpleural space?
Relaxation of the diaphragm
Decrease in the volume of the interpleural space
Increase of positive pressure
What is the role of the conducting airways?
Allow air to enter/exit
Filter, warm and humidify inhaled air
Epithelium is composed of several cell types
What is present on the trachea for protection and to keep it open?
Cartilage rings
What is the role of the bronchi?
Produce mucus to trap dirt particles and microorganisms
Mucus is then continuously cleared by the cilia to the pharynx and swallowed
In what group of people is cilia in the bronchi not functional?
Smokers
Do bronchioles have cartilage rings?
No
The pulmonary artery carries __________ blood
deoxygenated
Bronchial circulation provides ___________ blood to larger airways
oxygenated
What is the radius and thickness of an alveolus?
0.1mm radius and 0.2um wall thickness
What is the role of the alveoli?
Primary site of gaseous exchange and passive diffusion
The alveolar wall consists of a single layer of ___________ cells
epithelium
The capillary wall consists of a single layer of ___________ cells
endothelial
Erythrocytes contain _________ and ___________ anhydrase
haemoglobin carbonic anhydrase
Carbonic anhydrase is important in the elimination of __________
carbon dioxide
Carbon dioxide is mostly transported dissolved in the plasma as ______
HCO3-
What are the 8 steps in gas exchange, starting with inhalation?
Inhalation - air from environment -> alveoli
Diffusion of oxygen from alveoli to lung capillary
Oxygen diffuses to RBCs and binds to haemoglobin
Systemic capillary - oxygen leaves haemoglobin and diffuses into tissue
CO2 goes from tissues to capillaries and is converted to HCO3- in erythrocytes
HCO3- travels in plasma to lungs where it is converted to CO2
CO2 diffuses across lung capillary wall into alveoli
Exhalation
What are alveolar macrophages derived from?
circulating blood monocytes
What are alveolar macrophages?
Phagocytic cells - provide defence against pathogens and inhaled drugs.
Which cytokine do alveolar macrophages secrete?
Interleukin-1a
In which two groups of patients is the efficiency of bacterial phagocytosis in the lungs reduced?
Smokers and COPD patients
How does lysosomal trapping of drugs in alveolar macrophages take place?
Basic drugs and macrolides accumulate in the AMs, in particular in the lysosomes as they are acidic. Basic drugs become ionised and trapping takes place due to reduced ability of the protonated form of the drug to diffuse back into the cytosol.
What does continuous drug accumulation in alveolar macrophages lead to?
Phospholipidosis - foamy AMs
What is asthma?
Chronic inflammation of the airways causing contractibility of smooth muscles, reversible narrowing of airways
What causes asthma?
Family history Eczema and allergy Second hand smoking Broncholitis Born prematurely Hormones
What are the different ways in which asthma can be treated?
Long-term treatment - inhaled corticosteroids, lukotriene modifiers, long acting beta agonists, combination inhalers
Quick relief medication - short acting beta agonist, bronchodilators, corticosteriods,
Allergy medications
What are the effects of COPD?
Inflammed ariways, damaged air sacs, narrowing of airways, difficulty breathing
What are the treatments options for COPD?
Stop smoking
Diet - eat well to prevent weight loss and infections
Exercise and pulmonary rehab
Oxygen therapy, surgery
Medication - Bronchodilator inhalers, steroid inhalers (reduce swelling)
Pulmonary absorption as a means of drug absorption offers rapid access to __________ circulation due to large surface area of lungs, instantaneous absorption
systemic
Does pulmonary absorption avoid first pass metabolism?
yes
What is the disadvantage of pulmonary absorption?
only 2-10% of aerosol dose is deposited in lungs, 90% of dose is swallowed
What are the three delivery systems for pulmonary drug administration?
Metered dose inhaler
Dry powder inhaler
Nebuliser
How does a nebuliser work?
Atomisation of the liquid formulation into a mist of droplets for inhalation. It is used to give high doses of reliever medicine in severe asthma attacks
How does a metered dose inhaler work?
Designed to deliver a specific dose of medicine. It releases aerosol of drug
How does a dry powder inhaler work?
Delivers drug to lungs in dry powder particles. It relies on inhalation airflow to deliver drug
