W25 The Respiratory System Flashcards
What are the main functions of the respiratory system? (4)
- Ventilation (The movement of air into and out of the lungs)
- External Respiration: Exchange of oxygen (O2) and carbon dioxide (CO2) between the air in the lungs and the blood.
- Transport of O2 and CO2 in the blood
- Internal Respiration: Exchange of O2 and CO2 between the blood and the tissues
What are some other functions of the respiratory system?
- Regulation of blood pH- Altering blood CO2 levels
- Voice production- Air movement past the vocal cords
- Olfaction- Airborne molecules are drawn into the nasal cavity
- Innate immunity- Protects against certain microorganisms and other pathogens - preventing them from entering the body and by removing them from respiratory surfaces
What is the respiratory system responsible for?
What does it consist of?
It exchanges O2 and CO2 between the air and the blood.
Consists of respiratory passages and lungs
Conducting zone and respiratory zone
What are the structures of the respiratory system?
Upper respiratory tract? (3)
Lower respiratory tract? (3)
Upper respiratory tract
* Nose and nasal cavity- Air enters (also through the mouth)
* Pharynx (throat)
* Larynx
-maintains an open airway
-protects the airway during swallowing (epiglottis)
-produces the voice
Lower respiratory tract
-trachea
-bronchi
-lungs
Features of the lungs:
Where are they situated?
- Within the thoracic cavity
- 2 lungs
-Separated by the mediastinum in which the heart is situated - Each lung is divided into lobes
- Left lung – 2 lobes (upper and lower)
- Right lung – 3 lobes (upper, middle and lower)
- Heart sits within the ‘cardiac notch’ so the left lung is slightly narrower
- Each lung: Surrounded by a pleural cavity
-Formed by 2 pleural membranes- the visceral and parietal pleurae - Passages branch
- Decrease in size
- Increase in number
What are cilia?
They line the surface of the lower respiratory tract
They beat upwards and drives the debris
What structure protects the respiratory tract when you swallow?
Epiglottis
Which structures are part of the conducting zone?
- Alveoli
- Terminal bronchioles
- Respiratory bronchioles
- Primary bronchi
- Alveolar ducts
Terminal bronchioles and Primary bronchi
Which structures are part of the respiratory zones? (3)
Alveoli
Respiratory bronchioles
Alveolar ducts
What are the 2 phases of Ventilation?
What is is regulated by?
What is air flow driven by?
- Inhalation (inspiration)
- Exhalation (expiration)
- Changes in thoracic volume (drives)
-pressure changes
Air flow is driven by the pressure difference between
* the atmosphere (barometric pressure)
* inside the lungs (intrapulmonary pressure)
What are the features of the diaphragm?
- 70 % ventilation
- Dome shaped
- Contracts
- Downwards and flattens
- (increasing thoracic cavity)
- Relaxes
- Recoils upwards
- (reducing thoracic cavity)
- Only respiratory muscle working when lying flat and sleeping
What are the features of the Intercostal Muscles?
- Between ribs
- Two planes of muscular and tendinous fibres occupying each intercostal space* Internal beneath external
- The external intercostal muscles * slope downwards and forward
- Contract: ribs upwards and outward
- Elevates ribs and sternum
- The internal intercostal muscles * Opposite direction
- Contract: lower ribs
- Stability
Forced breathing (During exercise or when you are breathing more forcefully):
- Muscles contract more forcefully
- Others also contract
- Scalene muscles
- Sternocleidomastoid
- Pectoral muscles
What is inspiration?
What are the steps?
Quiet breathing (in)
* Diaphragm contracts
* External intercostals- Contract
- Signals from the respiratory centre in the medulla oblongata (brain stem)
- Contraction of the diaphragm and intercostal muscles leading to the diaphragm moving downward
- Transverse expansion of thoracic cavity
- Vertical expansion of thoracic cavity
- Lung volume increases and the intra-alveolar pressure decreases
- Air is sucked in (inhalation)
What are conducting airways/zones?
What do they consist of?
- Strictly for ventilation
- The trachea (windpipe)
-Cartilage
-Splits into: - Left and right bronchi
- When an airway divides it always divides into 2 (bifurcation)
What does the bronchial tree consist of?
Bronchial tree
* Left and right bronchi (one bronchus) or primary bronchi divide
* Secondary bronchi (in lobes of lung) - divide
* Tertiary bronchi - divide
* Bronchioles – divide (several times)
* Terminal bronchioles
- Top of tree
-Lots of cartilage some smooth muscle
-Keep airways open
Bottom of tree
-Lots of smooth muscle less cartilage
-Change diameter of airways Bronchial tree
What does the respiratory zone consist of?
- Respiratory bronchioles * (few alveoli) attached
- become alveolar ducts
- 2/3 alveolar sacs
Alveoli
* Air-filled sacs
* Membrane v elastic- Expand / contract
* Surrounded by a capillary network to provide efficient gas exchange
* The respiratory membrane
-Where gas exchange between the air and blood takes place
-Very very thin
What are the types of alveoli? (3)
- Type 1 alveolar cells (95%) form the alveolar wall
- permit gas exchange - Type 2 alveolar cells secrete surfactant
-Defence
-Role in breathing and stabilises alveoli (surface tension)
-Recoil of lungs - Alveolar macrophages
-Defence against foreign particles/infectious microorganisms that reach the alveoli
What is the respiratory pressure cycle?
Air flow and pressure changes.
- Changes in volume result in changes in pressure
* As the volume of a container increases, the pressure within the container decreases
* Same for lungs
* Respiratory muscles change the volume of the thorax - Air flows from an area of higher pressure to an area of lower pressure
* The greater the pressure difference, the greater the rate of airflow
- Intra pulmonary/alveolar pressure
- Respiratory Muscles: change the volume of the thoracic cavity
- Air flow into and out of lungs
What are the Respiratory Muscles?
- Diaphragm
- Intercostal muscles (External&Internal)
- Scalene muscles
- Sternocleidomastoid muscles
- Pectoral muscles
- Abdominal muscles
Features of the Diaphragm:
- 70 % ventilation
- Dome shaped
- Contracts- Downwards and flattens (increasing thoracic cavity)
- Relaxes- Recoils upwards(reducing thoracic cavity)
- Only respiratory muscle working when lying flat and sleeping
What are the features of the Intercostal Muscles?
Where are they situated?
Which way do the external and internal muscles face?
- Between ribs
- Two planes of muscular and tendinous fibres occupying each intercostal space
-Internal beneath external - The external intercostal muscles
-slope downwards and forward
-Contract: ribs upwards and outward
-Elevates ribs and sternum - The internal intercostal muscles
-Opposite direction
-Contract: lower ribs - Stability
What are the steps in the active process of Inspiration?
- Signals from the respiratory centre in the medulla oblongata (brain stem)
2.Contraction of the diaphragm and intercostal muscles leading to the diaphragm moving downward - Transverse expansion of thoracic cavity & Vertical expansion of thoracic cavity
- Lung volume increases and the intra-alveolar pressure decreases
- Air is sucked in (inhalation)
What is expiration?
What are the steps of muscles move in expiration?
- Quiet breathing
- Relatively passive
- Elastic tissue (lungs thorax)
- Lung recoils
- When…..
- Diaphragm relaxes
- Domes (decreases volume)
- External intercostals relax
- Downwards and inwards (decreases
volume) - Laboured exhalation
- Internal intercostals contract
- Abdominal muscles contract
End of Expiration
- Alveolar/intra-pulmonary pressure = atmospheric pressure
- No air movement
End of Expiration
- Alveolar/intra-pulmonary pressure = atmospheric pressure
- No air movement
Pleural pressure
- Pleural Pressure ( the pressure in the pleural cavity)
- Normally lower than alveolar pressure.
- Suction effect - fluid removal by the lymphatic system
- Negative pressure difference (lower pleural pressure
than alveolar pressure) keeps the alveoli expanded - Pulls the pleura away from the outside of the alveoli
- Pressure on the alveoli is lower
- Expansion is opposed by the tendency of the lungs to
recoil
Pneumothorax : Pleura pierced
- Air introduced
- Pleural pressure is not low enough to overcome lung recoil
- Alveoli collapse
Air flow and pressure changes
End of Expiration
* Alveolar/ intra pulmonary pressure =
atmospheric pressure
* No air movement
- Inspiration
- Increased thoracic volume →
- Increased alveolar volume
- Decreased alveolar pressure
- Atmospheric pressure > alveolar
pressure - Air moves into lungs
End of Inspiration
* Alveolar pressure = atmospheric
pressure
* No air movement
Expiration
* Decreased thoracic volume
* Decreased alveolar volume
* Increased alveolar/intrapulmonary pressure
* Alveolar pressure > atmospheric pressure
* Air moves out of the lungs
Exhalation
Passive process (elastic potential energy)
- A passive event due to elastic recoil of the
lungs - Relaxation of diaphragm and external
intercostal muscles - During forced expiration, ONLY there is
contraction of abdominal, internal
intercostal (accessory muscles)
Respiratory Muscles
- No inherent rhythm
- Generate tension due to rhythmic pattern of neuron-induced action potentials activating them
- Muscles attempt to overcome the resistance to airflow within the airways
- When at rest, the thorax assumes the FRC (Functional Residual capacity) position
Respiratory Function: measurement
- Spirometry is the process of measuring volumes of air that move into and out of the respiratory system
- Measurements of the respiratory volumes can provide information about the health of the lungs
- Peak Flow
- Many more
- Static Lung Volumes
- Volumes/capacities
- Dynamic Lung Volumes
- How quickly air can be inspired/expired
Volumes and Capacities
- Respiratory volumes:
- Measures of the amount of air movement during different portions of ventilation,
- Respiratory capacities
- Sums of two or more respiratory
volumes. - The total volume of air contained in the respiratory system ranges from 4 to 6 L
What is Tidal Volume (TV)?
- The volume of gas expired/inspired in one breathing cycle
- Also known as ‘resting’ or ‘quiet’ breathing
- Around 500ml (info)
What is Inspiratory reserve volume?
- Inspiratory reserve volume is the amount of air that can be inspired forcefully beyond the resting tidal volume
What is Expiratory reserve volume?
- Expiratory reserve volume is the amount of air that can be expired forcefully BEYOND the resting tidal volume.
What is Residual volume?
- Residual volume is the volume of air still remaining in the respiratory passages and lungs after maximum expiration (you cant breathe it out)
- Without a residual volume, the lungs would completely collapse and the pressure required to generate inflation would be high
What is Total lung capacity (TLC)?
- The volume of gas in the lungs and airways at a position of full inspiration –therefore we are measuring how much air the lungs can
actually hold - Lung expansion is limited at a point which defines TLC
- Consists of IRV + TV + ERV + RV
What is Vital Capacity (VC)?
- The total volume of gas that can be expired from the lungs from a position of full inspiration/ the total volume of gas that can be inspired
from a position of residual volume - This is similar to an FVC manoeuver except it is not forced
- Consists of IRV + TV + ERV
What is the Inspiratory capacity?
- The tidal volume plus the inspiratory reserve volume
- The amount of air a person can inspire maximally after a normal expiration
- Consists of IRV + TV
What is Functional Residual Capacity?
- The volume of gas in the lungs and airways at the end of a tidal breath
- This is the point at which the inward pull of the lungs and the outward pull of the chest wall are in equilibrium
- Consists of ERV and RV