Respiratory Flashcards
What is the overview pathway of the respiration system from nasal cavity
Into the nasal cavity, pharnyx, Larynx, Trachea and then in to left and right bronchi into lots of tubes called bronchioles and then to the respiratory bronchioles, alveolar ducts + sacs and then alveoli.
What is the overall definition of respiration and the 3 places it takes place
Respiration is a general term for the transfer of gas (CO2 and O2) across a boundary/membrane/somewhere different.
3 places is external, internal and cellular
Compare the 3 places that respiration takes place
External: transfer of gases from external atmosphere to blood through pulmonary capillaries
Internal: transfer of gases from blood to tissues and interstitial fluid via systemic capillaries
Cellular : where O2 is consumed and Co2 is produced
What is Pulmonary Ventilation. How does it relate to ventilatory pump
The mechanical bulk movement of air in and out of the lungs. It uses the ventilatory pump= rib cage, associated muscles and diaphragm
Compare the two functional classifications of the Respiratory system. What are they
Conducting zone: series of cavities, thick walled tubes that conduct air from the nasal cavity to the bronchioles. It warms, cleans and humidifies the air
The respiratory zone: is the tiny thinwalled airways where gas exchange occurs. (respiratory bronchioles -> alveoli)
Upper vs lower RTract:
Where is a blockage of the respiratory tract worse.
Where is an infection worse
A blockage is worse in the upper conducting pathway because there are more branches in the lower tract.
Whereas an infection is better in the upper tract because the respiratory zone is much closer with blood supply and therefore can grow more easily/ get into the blood
What are the anatomical/structural classification of the respiratory system.
Upper Respiratory tract : Nose ->larynx
Lower Respiratory tract: Trachea- alveoli
What is the three ‘stops’ where oxygen bus goes from outside to inside the body and CO2 goes from inside to outside
First stop - ventilatory pump as air
2nd stop- Left cardiac pump (in blood)
3rd stop- Cells in tissue where CO2 is produced.
Co2 then goes to Right cardiac pump and then back to the ventilatory pump
What is the overall purpose of the nasal cavity
Prepares the air for gas exchange by making it
Warm the air to 37’
Clean - filtering
Wet - humidify (100% saturated)
What features of the nasal cavity help to filter the air
Vibrissae -coarse hairs filter big particles
Respiratory epithelium mucous
Seromucus gland close to the entrance of nose
What features of the nasal cavity help to humidify the air
Respiratory epithelium mucous helps to transfer moisture to dry air
Seromucus gland close to the entrance of nose
What features of the nasal cavity help to warm the air
Rich blood supply underneath the epithelium that is vasodilated and close to the surface to allow heat exchange
What are Turbinates (bones) structure and function
3 conchae of the lateral nasal cavity wall (sup, mid, inf) that increase the SA of the nasal cavity. It slows the air and causes turbulence. This allows the air to slow down for filtering, warming and humidifying.
What is the movement of mucocillary escalator in the respiratory epithelium - where is it moving things
The cillia move the mucus layer on top in a concerted mexican wave towards the throat
What is the structure and function of the paranasal sinuses
They are cavities behind the lateral nasal cavity walls connected by little holes make your head light and provide a resonance and tone to your voice.
What are the 3 parts of the pharynx and what is the difference between then
Nasopharynx which connects the Nasal cavity.
Oropharynx that connects the oral cavity
Laryngopharynx that connects the larynx and throat.
How is food kept out of the airway
When we swallow, the nasopharynx is closed by the soft palate which pushes the food down into the posterior eosophagus. The bolus of food passively pushes the epiglottis, a flap of elastic cartilage covered in epithelium closed over the air way. Then springs back after food gone
What are the generations of branches of bronchi that are part of the conducting zone
Main stem bronchi
Lobar bronchi
Segmental bronchi
4-9 Smaller bronchi
10-15 Bronchioles
16-19 Terminal bronchioles
What are the generations of branches of bronchi that are part of the respiratory zone
20-23 Respiratory bronchi (where air is clean)
24-27 Alveolar ducts
28 Alveolar sacs
Describe the main features of the Trachea:
Its tube as thick as your thumb anterior to the chest. It has a stiff C shaped rings of cartilage with the posterior ends connected by trachealis muscle.
It is lined with the respiratory epithelium that has mucocilary escalator towards the nasopharynx.
Where does the oesophagus sit in relation to the trachea
It is dorsal to the trachea lying on the trachealis.
What are main trends in the diameter, epithelia as you continue branching into 2 from bronchus/trachea to bronchioles further
The diameter reduces. The complexity of the cells decrease (less conditioning needed)
The epithelia height reduces in the form of going from pseudostratified columnar to cuboidal to squamous because we need to have thin cell layer for gas diffusion to be good.
What are the layers within the bronchus wall from air to before the alveoli
Pseudostratified cillated columnar epithelium + goblet cells
Smooth muscle layer
Mucous glands
Cartilage plates
What are the two sources of mucus in the trachea and bronchus
Goblet cells and mucous glands
What are the layers within the bronchioles wall from air to before the alveoli
Simple cilliated columnar/cuboidal epithelium + club cells
Smooth muscle
Are the alveoli part of the bronchus/bronchiole wall?
No
What are the main differences between the structure of bronchus walls vs bronchiole walls
Bronchus still air conditioning whereas Bronchioles not really so Bronchus has 2 places for mucous but Bronchioles have club cells that secrete a watery secretion that helps with hydration and antimicrobial enzymes
In bronchus smooth muscle layer doesn’t rlly keep it open bc it has cartilage to do that, but in Bronchioles It doesn’t have Cartilage so smooth muscle layer is important for bronchodilation/constriction and controlling air to respiratory zone
What is the mechanism of acute asthma attack and how is it treated
Triggered by heat, pollen, dust etc there is rapid bronchoconstriction which reduces airflow to respiratory zone. Treated with bronchodilators which relax smooth muscle (salbutamol)
Describe the 3 structures of the respiratory zone
The respiratory bronchioles that have same wall structure as other bronchioles but have small buds of alveoli where gas exchange can take place
Alveolar ducts: tubes formed by alveoli
Alveolar sacs: bunch of alveoli that extend from one branch
Describe the cells in the alveolar wall
Type 1. Squamous pneumocyte, thin bordering with capillaries for gas exchange
Type 2: Surfactant cells: secrete surfactant liquid which keeps the alveolar open
Type 3: Alveolar Macrophage: wandering cell, last line of defense against microbes
What is the importance of surfactant in alveolus and how does it relate to Work of breathing
Surfactant prevents the collapse of the alveolus on expiration by decreasing surface tension. Made of phospholipid that repels each other. This reduces the work of breathing
What is work of breathing
the energy required to get air in (inspire) and inflate the structures
Identify what constitutes a diffusion barrier - also called Blood air barrier (0.5 um)
It has squamous pneumocyte facing the air space. The basement membrane of Sq. pnu. is fused with the basement membrane of capillary endothelium to make it uniquely
Then there is the capillary endothelium that opens to blood plasma
What type of respiration takes place at the diffusion barrier and what type of disease can affect it
External respiration. Fibrosis increases the connective tissue in the basement membrane layer which increases distance for diffusion and therefore can lead to hypoxic blood.
What are the main subdivisions of the lung and what bronchi supply them
There is a right lung and left lung supplied by 1’ bronchi
There are 2 left lobes and 3 right lobes supplied by 2’ bronchi
There are 8 left segments on the left and 10 segments on the right. Each supplied with its own 3’ bronchi and blood supply.
What covers the blood vessels, lymphatic fluid and air supply to the segments of the lung
connective tissue
What is the clinical significance of lung segments
Surgeons can remove localised tumours in the lung within 1 or 2 segments without excessive leakage of blood or air from other segments
What is the structure of the pleurae
The visceral pleura covers each lung and the parietal pleura covers the thoracic cavity. The place where the ends join is at the hilum. This is filled with a pleural space with a thin layer of pleura fluid.
What is the function of the pleurae
The pleural fluid allows the pleurae to slide past each other without friction. It also prevents the two layers from being separated, allowing the movements of the thoracic wall and diaphragm to affect the volume in the lungs.
What is the mechanics of the muscles that help inspiration
In inspiration the external intercostal muscles contract and the diaphragm contracts.
External intercostal muscles causes inspiration because as they contract the ribs pivot around their joints in the vertebral column and lift the rib cage up and out.
When Diaphragm contracts, it flattens the central tendon which pulls the dome downwards and increases the volume of the thorax
What are the mechanics of the muscles that help expiration
Expiration is a passive process at rest where diaphragm passively relax and rib cage returns to resting position. In active processes the internal intercostal muscles (at right angles to external intercostal muscles) contract and drag the rib in and down.
What is the ratio of intercostal muscles to diaphragm with rest breathing vs exercise breathing
At rest, movement of the ribcage is 25% and diaphragm is 75%, however in exercise the ribcage contributes more to exercise
Describe the structure of the diaphragm: shape and components
Dome shaped platform that has a central part of thin connective tissue (aponeurosis) callled central tendon and lateral margins of skeletal muscle attaching to the sternum and vertebrae.
Define respiration
To extract oxygen fro the air and together with the cardiovascular system transport it to respiring tissues
2. To remove carbon dioxide from respiring tissues and exhaust into the atmosphere
As respiration evolved from diffusion in protozoa, to lungs in reptiles and mammals what were the main factors that drove the change
There was increase in the size of the tissue, therefore distance for diffusion increased.
Increase metabolic rate means more gas needed
List the main muscles associated with breathing and their nervous innervation
Diaphragm is innervated by phrenic nerve which comes from phrenic motor nucleus (C3-C5)
-The internal (exp) and external (insp) intercostal muscles are innervated by the internal and external intercostal nerves that come from the intercostal motor neurones (T1-L1)
-The abdominal muscles are innervated by the abdominal nerve which comes from the abdominal motor neurones (T7-L1)
Where do the nerves that innervate the muscles for breathing go to from the spinal cord
These motor neurons are excited by the brainstem (medulla oblongata +pons) which makes a neural rhythm to control expiration and inspiration to occur not at the same time. However there is the ability to voluntarily adjust breathing
When are the abdominal muscles involved breathing
During active expiration. (eg cough, laugh, exercise) Doesn’t contract at rest.
What is the intra pleural pressure vs the intra pulmonary pressure
The intra pleural pressure is the pressure inside the pleural cavity outside the lung and the intra pulmonary pressure is the pressure within the lung, within the respiratory zone
How does the respiratory volume , intra pulmonary pressure and intra pleural pressure change during inspiration
The pleural pressure decreases from a negative pressure to an even more negative pressure. This causes the intra pulmonary pressure to go from atm down to negative pressure. This causes air to move from higher pressure (atm) to lower pressure, increasing volume of air in lungs. As volume increase to a peak the pulmonary pressure rises back up to atm (in a cup shape) .
How does the respiratory volume , intra pulmonary pressure and intra pleural pressure change during expiration
The intra pleural pressure starts to rise from its most negative point back to becoming less negative as air leaves. This causes the pulmonary pressure to become more positive relative to atm. This means that air moves out so the volume decreases from the peak of the bell curve back down to 0.
Why is it important for the pleural cavity to have a negative pressure in regards
This means that the visceral and parietal membranes stick together joining the chest wall to the lungs. This means that the lung doesn’t collapse
What is Pneumothorax
Thoracic puncture wound where air rushes into the chest and there is a loss of the negative pressure of the pleura. The lung moves away from the chest wall and deflates and its hard to maintain those changes in pressure to inflate the lungs
How does the lungs inflate
As the diaphragm and intercostal muscles contract they increase the volume of the intra pleural space and this also increase the volume of the intra pulmonary space This means that the pressure of the intra pleural space decreases. As a result the atm tries to equalise the pressure by pushing air inside the lungs.
How is lung volume measured
With spirometer where the oxygen volume in a floating drum (floating in water) is attached to a tube to breathe into means that while breathing you can push the drum up and down and measure the volume
What is the difference between a respiratory volume and capacity
Volume is measured whereas capacity is calculated from the measured values
What is the tidal volume
This is the normal resting volume that comes in when you breath (peak to trough)
What is the inspiratory reserve volume vs the expiratory reserve volume
Inspiratory reserve is the maximum volume that can be inhaled after the peak of the normal tidal breath. Whereas expiratory reserve is the maximum volume that can be expired after the expiration of a tidal breath
