Lecture 2 Flashcards
What is the symbol for atmospheric pressure at sea level (also called barometric pressure)?
- What are the two types of gauge pressures?
- What are the specific examples (3)
- mm Hg and
- cm H2O
If PB is 760 mmHg and PA is 755 mmHg
- What is the gauge pressure?
PA - PB
- -5 mmHg
the higher the altitude what happens with atospheric pressure?
lower the atmospheric pressure
- How does the animal produce pressure changes in the alveoli?
(what is PA at during the stages of respiration)
- PA low during inspiration
- PA high during expiration
- PA zero – during pause or no air flow
What is Boyle’s Law?
At a constant temperature, the same amount of gas will decrease in volume with an increase in pressure
How is the animal able to change the volume in the lungs and dimensions of the thoracic cavity? (generally 3 ways)
- Muscles of ventilation
- Direction of ribs/thoracic cage movement
- Ppl (pleural pressure) and PA (alveolar pressure) pressure changes during ventilation
Which muscles are used for inspiration
- Diaphragm
- External intercostals
- Abductor muscles of nares and larynx
what muscles are used for exhalation
- it is passive
- Exceptions: coughing and sneezing
- Internal intercostals
- Abdominal muscles- Active
fill in for inspiration
fill in for expiration
What is visceral pleura?
serous membrane covering lungs
what is Parietal pleura?
serous membrane covering the thoracic wall
Between parietal and visceral pleura is what
Very thin layer of fluid
- what type of pressure is in the interpleural space, positive or negative
- how does this happen?
- negative
- is related to the blood flow in the capillaries of the pleura and the blood-gas tensions within those capillaries
- what happens to pleuural pressure during inspiration?
- expiration?
- what does that change in pleural pressure allow for in the alveoli?
- Starts at resting level, goes more negative at inspiration, and
- comes back to resting level at the end of expiration
- The change in the pleural pressure causes the change in the alveolar pressure which in turns causes the air to flow in, resulting in the change in lung volume
explain what happens to….. during insipration for most animals (excluding equine)
- lung volume
- air flow
- pleural pressure
- alveolar pressure
- lung volume- goes up
- air flow- goes up and then down
- pleural pressure- goes down
- alveolar pressure- down then up
what happens to …. during expiration for most animals (excluding equine)
- lung volume
- air flow
- pleural pressure
- alveolar pressure
- lung volume- goes down
- air flow- down then up
- pleural pressure- goes up
- alveolar pressure- up then down
diagram intrapleural pressure for the horse during inspiration and expiration
diagram alveolar pressure for a horse during inspiration and expiration
diagram air flow for a horse during inspiration and expiration
- What is Vt?
- IRV
- where would each of these be on a lung capacity graph?
- Vt= Tidal Volume
- Volume of each breath
- IRV - Inspiratory Reserve Volume
- Extra Volume That Can Be Inhaled After a Normal Inhalation
- What is ERV
- RV
- where would each of these be on a lung capacity graph?
- ERV - Expiratory Reserve Volume
- Extra Volume That Can Be Exhaled After a Normal Expiration
- RV - Residual Volume
- Volume in the lungs after complete exhalation
- What is IC
- equation?
- VC?
- equation?
- how are they on a lung capacity graph?
- IC = Inspiratory Capacity
- IC = VT + IRV
- VC = Vital Capacity
- VC = IRV + VT + ERV
- What is FRC?
- equation?
- TLC?
- Equation?
- where are they on a lung volume graph?
What is pleural fluid?
This fluid helps to lubricate parietal and visceral pleura so that there is not a lot of friction, and may act to adhere the two layers gently together.
What factors are strong collapsing forces within the lung?
- Lung elasticity- Elastic and collagen tissue
- Surface tension present at liquid-air interface
- between cattle horse and dog which animal has smallest amount of tital volume /kg
- middle?
- largest?
- Cattle - 8 ml / kg
- Horse - 12 ml / kg
- Dog - 15 ml / kg
Why do cattle have a small tidal volume?
have small chest cavity because of large rumen size
- during increased respiratory rate will tital volume increase or decrease?
- what about alveolar ventilation?
- decrease
- decrease
What is function of surfactant
- there is high surface tension at the liquid air interface, and this force wants to collapse the lung.
- Surfactant lines the alveoli and reduces the surface tension that is acting to constrict the lung.
- Where is surfactant produced
- what component is responsible for its primary function?
- type II alveolar cells
- It is a mixture of lipids and proteins made from .
- Dipalmitoylphosphatidylcholine
if there is more surfactant what happens to surfance tension?
surface tension decreases
What is elastic recoil of the lung?
- During inspiration- contract diaphragm to make chest wall bigger and by relaxation of the diaphragm the chest wall goes back to its equilibrium again (elastic recoil of the lungs pulling the chest wall back to the equilibrium point).
- This action creates negative pressure between the parietal and visceral pleura within the pleural fluid.
- what is the most important lung capacity?
- why?
- Functional Residual Capacity (FRC = Expiratory Reserve Volume (ERV) + Residual Volume (RV)) is the most important of the capacities.
- This is the volume of gas in the lung that the animal is living off of in between breaths- during pause between breaths.
- Gas exchange occurs constantly because of this capacity.
what is the compliance of lung equation?
ΔV/ΔP
- Change volume / change pressure
when you increase respiratory rate what will happen to alveolar ventilation?
- it will go down
- will have more gas coming out of lungs and alveolus will not be ventilated as well
- what is hypoxemia?
- hypoxia?
- Hypoxemia- low oxygen in blood
- Hypoxia- low oxygen in tissues
How do you calculated alveolar ventilation?
Va= volume of alveolar gas
f= frequency (respiratory rate)
VT = Tidal volume is a mixture of gases from?
Vt= Va + Vd
tidal volume= volume of alveolar gas + (anatomic + alveolar dead space)
How much air is breathed per minute?
- what is the equation?
- what is the equation for change in pleural pressure
- what is it always measured in?
- Change in volume/ compliance + (resistance x volume)
- cm H20
- what is equation for transpulmonary pressure?
- why is it important?
- alveolar pressure - pleural pressure
- It is what helps to keep alveoli open
what is 1 stating
1- a high pressure is required initially to inflate the lung with air from the gas-free state
2?
the lung reaches its elastic limits (total lung capacity) at PL of approximately 30 cm H2O
3?
- the lung’s elastic properties differ during inflation and deflation;
- less pressure is necessary to maintain a given volume during deflation than during inflation (a phenomenon known as pressure-volume hysteresis)
what is hysteresis?
deflating lung
4?
- when saline is used instead of air to inflate the lung, less pressure is required for inflation, and the pressure-volume hysteresis is abolished.
- Pressure-volume hysteresis is a result of changing surface tension forces.
- High surface tension is also responsible for the high pressure required initially to inflate the lung.
- When the lung is inflated with saline, the air-liquid interface is abolished and so is pressure-volume hysteresis; the lung becomes easier to inflate
Does a ‘stiff’ lung (pulmonary fibrosis) have a compliance that is greater than or less than normal?
less than normal
- the thoracic cage’s compliance is more or less compliant in large animals?
- newborns more or less?
- large animals less compliant
- newborns more compliant
what is atelectasis
portion of all part of lung collapses
- what is poiseulle’s law?
- what is the equation?
- airway resistance
- pressure difference divided by the airflow rate
2.
- pressure difference divided by the airflow rate
do the airways present resistance to movement of air?
•Airways present frictional resistance to the movement of air
what part of conducting system has the highest resistance?
- 60% of total resistance
- Nasal cavity, pharynx, and larynx
what is the effect of open mouth breathing regarding resistance to airflow?
Will decrease resistance because don’t have to go through turbinatesm nasal cavity, pharynx and larynx
regarding the rest of the 40% of resistance to airflow which parts have the highest resistance (trachea, bronchi, bronchioles)
–Tracheobronchial tree – 80% of which is in the larger airways
when lungs inflate do the airways need to dilate or constrict?
dilate
