Tags & Description
2 types of respiration
Internal and external
Pulmonary capillaries
Surround the alveoli
How many sets of branches in the lungs?
24
What are the 2 zones of the lungs?
Conducting and respiratory
What is the function of the conducting zone of the lungs?
Way of transporting gases into the respiratory zone
What makes up the conducting zone?
Nose, mouth, pharynx, larynx, trachea, bronchi, bronchioles, and terminal bronchioles
What number branch is the bronchi?
11
What branch is the 0?
Trachea
What supports the bronchi?
Cartilage
What supports the bronchioles?
No cartilage Rely on tissue around them and their elastic nature to keep them open Much more subject to contraction
Why is it more efficient if we breathe through our nose?
Small hairs help filter and trap particles As the air is moving through it creates a turbulent type condition - smaller particles are more likely to drop our or get trapped because of this
Why is it beneficial for air to warm to our body temperature?
Warming gas helps prevent the formation of bubbles
What can carry more gas warm or cold air?
Cold
What stops the lower airways from drying out?
As air passes through it becomes humidified and equilibrated with water vapour
What controls the contraction of bronchi?
Smooth muscle underneath the cartilage lining the outside of bronchi under the control of para/sympathetic innervation
Epithelia mucous gland
Secretes mucus onto surface of bronchi to help trap particles
Function of elastic tissue in the airways
Recoil and helps to support
Function of ciliated epithelium in the lumen of the airways?
Helps direct mucus out of the lungs towards the throat to move small particles out of the lungs
Goblet cells
Produce mucus
Function of sensory nerve endings between epithelial cells in bronchi and bronchioles
Help detect noxious chemicals in the airway e.g. smoke
Diameter of bronchioles
Less than 1mm
What keeps bronchioles open?
Tethering of tissue around them - elastic tissue connection helps keep them open
What breaks down in COPD?
The elastic tissue surrounding the bronchioles subjecting them to collapse
Why do the bronchioles have proportionally more smooth muscle cells compared to the bronchi?
Controlling the airway diameter is more important
How many alveoli?
300 million per lung
Surface area of alveoli?
100 m2
How many biological membrane does oxygen have to diffuse across?
5
Inspiration pressure gradients
Atmospheric pressre is greater than the pressure inside the alveoli so gas moves down the pressure gradient and into the lungs
Expiration pressure gradients
Pressure in alveoli is greater than atmospheric pressure so gas moves down the pressure gradient and out of the lungs
What is the primary muscle of inspiration?
Diaphragm
What muscles does quiet inspiration involve?
Primary
What happens to the diaphragm during inspiration?
Contracts and moves down
ICE ECI
Internal contract expiration External contract inspiration
Boyle's Law
P1V1=P2V2
What muscles are involved in forced inspiration?
Secondary muscles
Scalene muscle function in forced inspiration?
Attach to top of rib cage - contraction helps move the rib cage up and forward
Function of sternocleidomastoids in forced inspiration?
Attach to the sternum - and helps to lift the sternum up and forwards
What is the function of neck and back muscles during forced inspiration?
Pull pelvic girdle up
Function of elastic tissue in quiet expiration?
Recoil of the elastic tissue returns the lungs to their original size
Function of abdominal muscles in forced expiration?
Pull diaphragm up
Pleura
Double-layered membrane surrounding each lung
Parietal pleura
Outer layer of pleura lying closer to the ribs and chest wall
Visceral pleura
Inner layer of pleura lying closer to the lung tissue
Pleural cavity
Between parietal and visceral pleura
What is the pleural cavity filled with?
Serous fluid
Function of pleural cavity?
Allows lung and chest wall to move over each and prevent them from sticking together Enables free expansion and collapse of lungs Helps set resting lung volume
Pneumothorax
Collapsed lung - air in the pleural cavity Intrapleural space is at atmopsheric pressure and so force keeping lungs inflated is lost Elastic nature will take over and lungs will collapse
Is the pressure in the intrapleural space greater or less than atmospheric pressure?
Less
Compliance
Measure of how distensible the lungs are - how elastic they are
Concentration =
Change in volume/ change in pressure
As you inspire, what happens to intrapleural pressure?
Becomes more negative
Low compliance
Large pressure chaneg and small volume change - more work needed to expand the lungs
Pulmonary fibrosis
Build up of structural tissue in the lungs - more rigid so harder to expand Lower compliance of the lungs
High compliance
Small pressure change induces a large volume change
What can high compliance lead to?
Problems when expiring Emphysema/COPD Lost some elastic properties as a result of breakdown of tissue Airways can collapse Harder to breathe out
What are the 2 components of elastic recoil in the lungs?
Anatomical and surface tension
Surface tension in the lungs
Air/water interface - water molecules tend to be pulled into the body of water
Laplace's equation
P=2T/r
What produces surfactant?
Type 2 pneumocytes
Surfactant
Chemical produced in the lungs to maintain the surface tension of the alveoli and keep them from collapsing
What is surfactant composed of?
90% phospholipids and 10% proteins
How does surfactant prevent alveolar collapse?
Decreasing surface tension Inncreasing compliance
How does surfacant affect rate of inflation?
SLows
Production of surfactant decreases and causes what?
Pneumonia
What happens to surfactant in pneumonia?
Production decreases
What does surfactant prevent?
Oedema Reduces fluid entering alveoli
How are surface tensions balanced out between large and small alveoli?
Small alveoli have a higher density of surfactant compared to large
Dead space
Volume of lungs not involved in gas exchange
Anatomical dead space
Conducting zone volume - first 16 generations of airways
How much inspired air volume is dead space?
30%
At rest how many ml of air is in anatomical dead space?
150ml
Tidal volume
Amount of air we breathe in and out in one breath
Average tidal volume
500ml
Physiological dead space
Volume of lungs not participating in gas exchange Conducting zone + non-functional areas of respiratory zone Normally physiological dead space and anatomical dead space are almost identical
2 types of dead space in lungs
Anatomical and physiological
Vital capacity
Maximum amount of air we can breathe in and out
Residual volume
Amount of air remaining in the lungs after a forced exhalation
Total lung capacity
Residual volume + vital capacity
Forced expiratory volume
How much air can be forced out of the lungs in 1 second
Expiratory reserve volume
Amount of air that can be forcefully exhaled after a normal tidal volume exhalation
Vital capacity =
TV + IRV + ERV
Inspiratory reserve volume
Amount of air that can be forcefully inhaled after a normal tidal volume inhalation
Functional residual capacity
Volume of air remaining in the lungs after a normal tidal volume expiration
FRC =
ERV + RV