Respiration 1+2 Flashcards
Where is air blood barrier
Lines the alveoli
What are the 2 forces acting on the lungs when you breath and why?
Inward force:
Pleural membrane trying to pull away from the chest wall
due to the elastic nature of the lungs (try to collapse down to the minimum volume)
Outwards force:
Pleural membrane trying to pull away from the lungs due to the chest wall trying to expand
What is the structure of the respiratory epithelium?
1) Lines the lumen of the conducting zone
2) Cilliated epithelium
3) Has goblet cells
4) Has Mucous glands
5) Is innovated by sensory nerve endings
What is resistance in parallel?
In small airways
1/R1 +1/R2 + 1/R3…..
What is IRV?
Inspiratory reserve volume
Additional volume that can be inhaled after a quiet inspiration
What is resistance in series?
In large airways
R1+R2+R3….
What does the respiratory zone consist of?
The alveolar air ducts and alveolar ducts
What are the muscles used in quiet expiration?
No muscles involved, relies on ELASTIC RECOIL
What is TV?
Tidal volume
Amount of air entering and leaving the lungs each breath
Structure of the bronchioles?
Small diameter
NO CARTILAGE support (more chance of collapsing)
Lined by respiratory epithelium
What are the muscles used in forced expiration?
Accessory muscles:
INTERNAL intercostal muscles
Abdominal muscles
Neck and back muscles
What does the conducting zone consist of?
How many divisions?
The nose, nasopharynx, mouth, phayrnx, layrnx, TRACHEA, BRONCHIAL TREE
The first 16 divisions of the lung branches
What is surfactant and what does it do?
Composed of lipids and proteins and produced by type 2 pnueomcytes
Prevents smaller alveoli (with high pressures) from collapsing as the air moves into the larger alveoli (with low pressures)
How is CO2 transported in the blood?
As bicarbonate (HCO3-)
What is compliance a measure of?
How distensible the lungs are, a measure of elasticity
What are the functions of the conducting zone and why does it need to do this?
To humidify air (prevents airways drying out), warm air (prevents the air causing bubbles in the blood when it reaches organs) and filter air
What are the 2 types of dead space?
Anatomical - conducting zone
Physiological - conducting zone + non-functional parts of the respiratory zone
Should be equal
What is TLC?
Total lung capacity
Total volume that the lungs can contain
(VC+RV)
What is elastic recoil?
Lungs tend to collapse to the minimum volume
What disease causes a decrease in compliance?
Fibrosis
More work needed to inspire (smaller change in lung volume for the same pressure)
What is the equation of compliance?
C= change in volume/ change in pressure
What is Pneumothorax?
1) Collapsed wall of the lungs due to a puncture in the chest wall
2) Pips=Patm
3) No Sub atmospheric pressure
4) Lungs collapse to the minimum volume
What is IC?
Inspiratory capacity
Amount of air that can be breathed in after quiet expiration
(TV+IRC)
What is RV?
Residual volume
The amount of air left in the lungs after expiration with maximum effort. Prevents collapse
What are the two components of elastic recoil?
Anatomical
Surface tension
What is the process of quiet inspiration?
1) Diaphragm moves down into the abdomen
2) External intercostal muscles move upwards and outwards-bringing the ribcage up and out
3) Increase in lung and thoracic volume
4) Air moves down the pressure gradient
How does the ANS control airway diameter?
PNS - ACh acts on muscarinic receptors leading to constriction
SNS - Noradrenaline acts on B2 causing bronchodilation
What is ‘Boyles law’?
An increase in volume leads to a decrease in pressure
What is inspiration and what is the pressure difference between the Patm and the Palv?
Breathing in
Patm>Palv
What are the muscles used in quiet inspiration?
involves primary muscles:
Diaphragm
EXTERNAL intercostal muscles (between the ribs)
What is Laplace’s equation and what does it show?
P=2T/R
T is surface tension (a constant)
R is the radius (an independant)
This shows that a bubble with a smaller radius will need a higher pressure to keep it inflated
What do the sensory nerve endings in the respiratory epithelium do?
Project into the lumen, respond to toxins in the air
Produce the cough reflex and close the airways
What disease causes an increase in compliance?
Emphysema
More difficulty to expire as lungs loss of elastic recoil (bigger change in lung volume for the same pressure)
What is FRC?
Functional residual volume
The amount of air left in the lungs after quiet expiration
(ERV+RV)
What are the muscles involved in FORCED INSPIRATION?
Primary inspiration muscles:
Diaphragm
External intercostal muscles
Accessory muscles: Scalenes Sternoclleidomastoids (in the neck) Back muscles Upper respiratiory tract muscles
What are the 3 features of the BRONCHIAL wall and the functions of each?
1) Cartilage rings - prevents collapse, keeps airways open
2) Smooth muscle layer - can alter the diameter of the bronchi
3) Elastic tissue - allows recoil
4)
What is Poiseuilles law?
Resistance = 1/Radius^4
(Resistance is inversely proportional to the radius to the power of 4)
So small changes to the radius can have large effects on the resistance
What is the normal compliance?
Pressure change of 2.5cmH2O gives volume change of 0.5litres
What do the mucous glands do?
Release MUCIN which dissolves to give a mucus layer above the cells - keeps the airways moist and traps particles
What is expiration and the difference between Patm and Palv?
Breathing out
Patm
How to calculate volume?
V= change in pressure / Resistance
change in pressure is (Palv-Patm)
What is surface tension?
Measure of force acting to pull a the molecules in a liquid together at a air-water interphase
Causes elastic recoil
How does surfactant work?
The lipids are ampipathic. The partition into the fluid and reduces surface tension
There is large amounts in the the small alveoli (to prevent collapse) and small amounts in the large alveoli (to prevent over inflation)
What is the sub atmospheric pressure of the lungs?
P(inter plural space)
What are the functions of the pleura?
The 2 membranes easily slide over each other allowing free expansion and collapse of the lungs
How many lung branches are there?
23-24
What is VC
Vital capacity
The maximum achevable tidal volume
(ERV+IRV+TV)
What humoral factors control airway diameter?
Adrenaline - dilation
Histamine - constriction
What is the pleural cavity?
In between the pleural membranes, filled with secretions.
Prevents the lungs sticking to the chest wall
What do type 2 pneumocytes do?
Linked to surfactant production
Why does surface tension occur in a bubble?
Water is attracted to each other, so a single water molecule has forces acting on it in all directions APART FROM where the air-water interface is
This causes water to dive down into the bulk of the liquid (away from the air)
This decreases the surface area of the bubble and increases the pressure inside the bubble
What are the pleura?
A double membrane which lines the lungs:
Visceral pleura lines the outside of the lungs
Parietal pleura lines the inside of the ribcage/chest wall
What are the two types of epithelial cells in the air blood barrier?
Type 1 and type 2 pneumocytes
What is FEV1
Forced expiratory volume in one second
What causes the pressure in the inter plural space
The pressure inside the pleural cavity is created when forces acting on the lungs balance, preventing collapse of the lungs
What is the function of the accessory muscles in inspiration?
To help pull the ribcage upwards and outwards quicker to make inspiration faster
What is ERV?
Expiratory reserve volume
The amount of air that can be expired after quiet expiration
What is the structure of the type 1 pneumocytes and what do they do?
Thin, flat cells
Involved in gas exchange
Form a ‘sandwich’ between the cell and the capillary wall
