The Respiratory System Flashcards
What is the function of the respiratory system?
○ Provide an extensive area for gas exchange between air and circulating blood
○ Moving air to and from exchange surfaces of the lungs along respiratory passageways
○ Protecting respiratory surfaces from dehydration, temperature changes and invading pathogens
○ Producing sounds for communication
○ Facilitating detection of odours by olfactory receptors in nasal cavity
Explain the respiratory defence system
-Respiratory mucosa lines conducting system (lines upper resp system and larynx, trachea and bronchi (conducting portion)
-Mucus produced by epithelial cells
-In nasal cavity, cilia sweep mucus with trapped particles downwards towards pharynx
-In lower respiratory system, cilia beat upwards towards pharynx
-Mucociliary escalator- prevents infection of the lungs
-Respiratory portion is the bronchioles and alveoli
-Once in pharynx, mucus is swallowed and subjected to stomach acid
What is the effect of the nose warming the air?
Warming and filtering air prevents the lungs from chilling, drying out and getting infected
Cools and dehumidifies outgoing air – air leaving the body is warm and humid, as it leaves it warms the nasal mucosa and moisture condenses on the surface. This prevents heat loss and water loss
What is the function of the epiglottis?
· Epiglottis forms a lid over the glottis formed of elastic tissue
○ During swallowing, closes over trachea to prevent food entering lungs
What is the anatomy of the lungs?
Lungs are surrounded by pleural cavities
-Coned-shaped
-Apex points superiorly-extends superior to first rib
-Base rests on the superior surface of the diaphragm
-Each lung is composed of lobes
-Lungs surrounded by pleura
-Pleural fluid
Right lung 3 lobes
Left lung 2 lobes, cardiac notch in left lung
Left lung slightly longer than right because the diaphragm rises on the right to accommodate the liver
-Pleural fluid – lubrication reduces friction between parietal and visceral pleura
Pleurisy when fluid does not prevent friction – pain and inflammation, breathing is difficult
What are the bronchioles?
· Each bronchus branches within the lung
· Forms narrower airways with progressively less cartilage
· Narrowest branches – bronchioles
○ Bronchioles are to the resp system what arterioles are to the CVS
-Bronchioles are very important as they control the air that gets into the lungs. Sympathetic stimulation of the smooth muscle causes bronchodilation and parasym activation causes bronchoconstriction
—bronchoconstriction in anaphylaxis is because of histamine released by mast cells
· No cartilage, abundance of smooth muscle
· Control airflow in lungs
What are the alveoli?
Site of gas exchange
· Each alveolus is associated with an extensive network of capillaries
· Alveolar epithelium composed of 2 cells types
○ Type I pneumocytes – sites of gas diffusion (Type I pneumocytes squamous epithelial cells very flat)
○ Type II pneumocytes – produce surfactant (Type II pneumocytes scattered amongst type I cells)
· Surfactant prevents alveoli collapsing by reducing surface tension throughout the lung
○ Surfactant is oily containing phospholipids and proteins , keeps alveoli open
-surface tension is the force present within the alveoli of the lungs that courses them to collapse and stick together during expiration.
What is boyle’s law?
P = 1/V
it shows the relationship between pressure and volume.
As volume increases pressure decreases, there is more room so fewer collisions between molecules
What is Dalton’s law?
→ The pressure exerted by a mixture of gases (in a fixed volume) is equal to the sum of the pressures that would be exerted by each gas alone in the same volume
What is gas exchange and where does it take place?
→ Gas exchange takes places between blood and alveolar air across a membrane
→ Occurs in response to conc. gradient
What is Henry’s law?
→ At a given temperature, the amount of a gas in solution in directly proportional to the partial pressure of that gas
Gas laws apply to the diffusion of O2, CO2 & N2 between alveoli and blood
Is gas exchange effective?
Gas exchange at the respiratory membrane is very efficient because:
→ Differences in partial pressure across the membrane are substantial
→ Distances involved in gas exchange are short
→ Gases are lipid soluble
→ Total surface area is large
→ Blood flow and airflow are coordinated
Rates of gas diffusion are greater when the differences in pp are highest
How is oxygen transported around the body?
· Small % O2 dissolved in plasma
· Majority bound to haemoglobin (Hb)
· Binding of O2 is reversible
○ If PO2 increases Hb binds O2, if PO2 decreases Hb releases O2
· Oxygen-haemoglobin dissociation curve
· Foetal Hb has a much higher affinity for O2 than adult Hb
· This ensures maximal transport of O2 across the placenta
How is carbon dioxide transported around the body?
· CO2 can travel in the bloodstream by:
· Being converted to carbonic acid
○ Chloride shift
· Binding to Hb
○ Forming Carbaminohaemoglobin
· Dissolving in plasma
Age related changes in the respiratory system
· Elasticity of lungs decreases reducing compliance and lowering vital capacity
· Arthritic changes restrict chest movements and limit the respiratory minute volume- older people may not be able to breathe in and out as deeply.
· A degree of emphysema is normal over the age of 50
○ Exacerbated by smoking
○ Emphysema is a type of COPD involving damage to the air sacs (alveoli) in the lungs. As a result, your body does not get the oxygen it needs.
