Respiratory System Flashcards
What is the role of the respiratory system?
Connected organs and structures that function to conduct warm, clean, moist air into close proximity with blood of the circulatory system for gas exchange.
Main components of respiratory tract.
Nasal cavity - Olfaction.
Conducting zone - Nose to bronchioles.
Oral cavity - Passage for air and food.
Respiratory zone - Bronchioles to alveoli, sites of gas exchange.
Epithelia in the respiratory system.
Epithelium attached via basement membrane to lamina propria. Epithelium changes along the tract to reflect function.
Conducting region epithelium?
Respiratory epithelium.
Epithelia where air and food travel?
Stratified squamous.
Epithelia at site of gas exchange?
Simple squamous.
Epithelia in nasal cavity?
Olfactory mucosa.
What type of epithelia is respiratory epithelium?
Pseudostratified ciliated columnar epithelium.
Structure of Respiratory epithelium?
Contains goblet cells that secrete mucus and ciliated cells for patterned movement of mucus towards pharynx.
Why does your nose run on a cold day?
Cilia are temperature sensitive, the colder it cold the less well they work. They stop beating and it will dribble out your nose rather than towards the pharynx.
Function of the URT
Conducting passage, not only for air. Prepares air for gas exchange by warming, cleaning and moistening.
Nose
Primary passage way for air. The front of the nose is cartilage while behind is bone. Vestibule (inside nostril) lined with skin and has sebaceous , sweat glands and hair follicles.
Conchae
Three projections that turbinate air.
Nasal mucosa.
Has a thin walled vascular plexus to help warm incoming air. This is where nose bleeds originate from.
What is a sinus?
Cavity within a bone.
What does paranasal mean?
Surrounding the nose.
Functions of the paranasal sinus.
Lighten skull, increase surface area, sound resonance.
Pharynx
Aka the throat. Is a tube shared by respiratory and digestive system. Has three regions the nasopharynx, oropharynx and the laryngopharynx.
What region of pharynx is an air passage only?
Nasopharynx.
Larynx
Aka the voice box. Air passage only. anterior tp esophagus. Located from the hyroid bone to the trachea.
Epiglottis
Closes over airway when swallowing.
Trachea
Between larynx and primary bronchi. functions to maintain patent airway with its c-shaped cartilage rings.
Trachealis
Bands of smooth muscle in trachea.
Mucociliary escalator
Moves debris to the pharynx to be swallowed and digested.
The lungs
2 lungs, 3 lobes on the right and 2 lobes on the left.
The hilum
Where the bronchi and blood vessels enter the lungs.
Regions of the lungs.
Apex (superior region).
Costal surface (against ribs).
Base (sits on diaphragm).
Bronchial tree.
Airways get smaller, the structure change to reflect how clean , moist and warm the air is.
Trachea –> primary bronchi –> secondary and tertiary bronchi –> bronchioles –> terminal bronchioles.
Respiratory zone.
Pulmonary lobules made of many alveoli which have very thin walls on simple squamous epithelium. The external surface of the alveoli is covered in fine network of pulmonary capillaries.
Pneumocytes
Lung epithelial cells.
Type 1 squamous
Forms the respiratory/blood air barrier with capillary wall and shared basement membrane.
Type 2 cuboidal
Scattered amongst type 1, a complex lipoprotein that reduces surface tension of alveolar fluid.
Role of roaming macrophage
Remove debri that makes it to alveoli .
The layers of the respiratory membrane.
Alveolar cell layer, fused basement membrane and capillary endothelium.
Pleural cavities
The lungs - seperate so if one stops working the other can still work.
What drives ventilation?
Pressure changes - pressure is inversely proportional to volume.
Boyles law
Air will move to a lower pressure space. To breath we need a pressure gradient, increase volume = air flow in etc.
Anterior thoracic joints
Sternocostal, costochondral and interchondral.
What anterior thoracic joint is cartilaginous?
Costochondral
Posterior thoracic joints.
Costotransverse and costovertebral. Both synovial.
Primary muscles of respiration.
Diaphragm and Intercostals
The diaphragm
Sheet of skeletal muscle which separates the thorax and abdomen. It is dome shaped when relaxed and flattens when contracted to pull air in.
Intercostal muscles
Attach diagonally between neighbouring ribs. External lift rib cage and expand cavity, internal depress ribcage and decrease cavity.
Inspiration.
Diaphragm contracts and external intercostal contract to lift ribs. Forced inspiration requires accessory muscles to contract as-well.
Expiration
Diaphragm relaxes and external intercostals relax. Forced expiration requires internal intercostals and accessory muscles to depress ribs.
Pluera
Makes lungs stick to thoracic wall.
Two opposing forces that must be overcome to take a breath.
- Stiffness of the lungs.
- Resistance of the airways to the lungs.
Lung stiffness
Defined as the magnitude of the change in the lung volume produced by the given change in the pressure.
Pulmonary fibrosis.
Thickening and scarring of the alveolar membranes, can arise from chronic inflammation or exposure to industrial chemicals.
Surface tension
Tendency of a fluid surface to occupy the smallest possible surface area. The water in alveoli makes it hard to expand.
Surfactant
Reduces surface tension in alveoli, produced by type II pneumocytes.
Where is the main area of airway resistance?
Bronchi
Spirometry
The pulmonary function test.
Tidal volume.
Volume of air moved in and out during normal quiet breath.
Inspiratory reserve volume.
Extra volume that can be inhaled over and above the tidal volume.
Expiratory reserve volume.
Extra volume that can be exhaled voluntarily after completion of a normal, quiet respiratory cycle.
Residual volume.
Volume remaining in lungs after maximal exhalation.
Minimal volume.
Volume remaining in lungs if they collapsed.
Vital capacity.
Total volume in lungs when maximally full.
Functional residual capacity.
Volume remaining in lungs after max exhalation.
Dead space
Some of the inhaled air never gets to the alveoli so cannot be used for gas exchange.
Daltons law
In a gas mixture, each gas exerts its own individual pressure called partial pressure.
Ficks law of diffusion.
Gases move across the membranes between the alveoli and the capillaries by diffusion.
What determines the rate of diffusion?
Surface area of the membranes.
Thickness of the membrane.
Pressure difference between the two sides.
What two forms is oxygen carried in the blood?
Dissolved O2 or bound to haemoglobin in RBC
Why does oxygen dissolve poorly?
Due to its low solubility at physiological partial pressure.
What can shift the Hb binding curve?
Bohr effect.
What three forms is CO2 transported in?
- Dissolved in plamsa.
- As bicarbonate.
- Combined with proteins.
Sensors involved with breathing.
Chemoreceptors, Lung stretch receptors, Baroreceptors and Protective reflexes.
Central controller of breathing.
Medulla.
Chemoreceptors
Located in the medulla, sensitive to PCO2 but not to PO2 of blood. Sense chemical changes.
What receptors are the most important in determining respiratory activity?
Carbon Dioxide receptors.
