Lecture 18 Flashcards
What is boyles law?
The pressure in a container decreases as the volume increases
What is the intrapulmonary pressure?
Pressure within lungs
Pulmonary ventilation vs. External respiration vs. Internal respiration
Atmosphere to lungs
Lungs to blood
Blood to cell
What is the intraplural pressure?
The fluid pressure in the pleural cavity
Around the lungs
756mmhg at rest (-4)
What is interplural cavity?
The alveoli pressure
Matches or is greater than ATM (760 mmhg - 762 mmhg)
What occurs during quiet inspiration?
Regular inhale by contracting intercostal muscles and pulling down the diaphragm to increase lung volume
Increased volume = decrease in pressure pulling air down [pressure] gradient
What happens during a forced inspiration?
Contraction of:
Intercostals, sternocleidomastoid, pecs, diaphragm, external intercostals
Increases volume of thoracic cavity and creates a greater pressure gradient to pull air in
What types of breathing are active processes?
Quiet inspiration/expiration
Forced inspiration/expiration
What occurs during quiet expiration?
Regular exhale breathing
Decrease thoracic size = increased pressure compared to atm moving down [pressure] gradient
762mmhg
What occurs during forced expiration?
Contraction of:
Internal intercostals, and abdominals
Relaxation of:
External intercostals, diaphragm
Increased pressure = decreased volume pushing [pressure] gradient to atm
What is compliance for breathing?
Compliance is the effort required to stretch lungs
Low comp = high effort
High comp = low effort
What is the stretch of lungs determined by?
The compliance and recoil depends on the elastic connective tissue
How are the collapsing of lungs prevented?
With negative pressure in the plural cavity that pulls the lungs out with the thoracic cavity
Decreased surface tension of alveoli by surfactant
Who are at risk of respiratory distress syndrome?
Newborns <7months due to the poor surfactant forcing alveoli to collapse
Decrease of compliance
How is airflow resistance determined?
By the diameter of bronchi
How is the airway manipulated?
SNS - dialates bronchioles smooth muscle - bronchodilation
PNS - contracts bronchiolar smooth muscle - bronchoconstriction
How are respiratory volumes measured?
Using a spirometer
1 respiration = 1 inspiration + 1 expiration
How much is the volume of air in a tidal volume?
500ml worth of air
Inspiratory capacity (3500 ml) - Inspiratory reserve volume (2500 ml) = TV (500 ml)
How much is the residual air volume?
Residual air after max expiration is 1200ml
What is expiratory reserve volume?
Excess air pushed out after TV
What is minute respiratory volume?
Tidal volume x respiratory rate = minute respiratory volume
6L/ min average
What 2 volumes make the Inspiratory capacity?
TV and IRV
What 3 volumes make the vital capacity?
TV + IRV + ERV
Largest in/out volume
What is the total lung capacity?
The max capacity of air in lungs
What is the average FEV1?
80% VC
What is FEV1 used for?
To diagnose if someone has an obstructive (less than 80%) or restrictive disorder (more than 80%)
What are characteristics and types of restrictive disorders?
Pneumothorax, scoliosis
Restrict lung expansion -> low IC/ VC/ FEV
FEV1 will be normal 80% range but will be lower on the chart since overall volume is lower
What are the partial pressures of O2 gas?
O2 - 21% of air => Pp = 0.21 x 760 = 160 mmhg for PO2
How is O2 transported in body?
Dissolved in plasma (1.5%)
Bound to hemoglobin (98.5%)
What is the partial pressure of O2 at lungs compared to organs?
It is higher at lungs at 105 mmhg and lower at organs at 40 mmhg
How many O2 molecules can bind to one hemoglobin?
1 O2 can bind to 1 heme group
4 heme groups per hemoglobin
4 O2 molecules can bind to one hemoglobin molecule
Explain the left shift in a oxygen dissociation curve
Left shift makes for low blood PCO2 meaning O2 loads easy and harder to unload
O2 is not in demand therefore less CO2 is made
Why do we use an O2 dissociation curve?
To measure the range of Hb picking up O2
The right shift mean more O2 demand and more CO2 is made
Left shift means less O2 demand and less CO2 is made from lack of effort
What pH condition makes O2 unload easier?
Lower pH
Right shift curve
Why does acidic environments unload O2 easier?
Because CO2 makes the blood acidic
O2 pulls CO2 off the hemoglobin resulting in right shift
What temperature makes for easier O2 unloading?
Increased temp causes shift to right
Think of exercise - increase demand makes more CO2 and temp
What 3 ways is CO2 carried in body?
Plasma
Hemoglobin bound
Bicarbonate ions (main way)
What is external respiration for CO2?
From capillary to alveoli
What is the chloride shift?
When a high [CO2] is present at tissue the chloride shift encourages more O2 to unload
Switches HCO3 for Cl into cell
What is the Haldane affect?
The kicking off of CO2 from a Hb at lungs to make room for O2
What is reverse chloride?
The using of Cl to move CO2 into the Hb once O2 leaves
Where is the respiration control center?
Medulla and pons
What does the medulla do?
Set breathing rate and rhythm
Inspiratory and expiratory neurons
How does the Inspiratory neuron send impulses?
Send it down the spinal cord to phrenic nerve (diaphragm) and thoracic nerve (exterior intercostals)
What is the role of expiratory neuron?
Fires inhibitory inspiration neurons since expiration occurs passively
What is the time ratios between inspiratory neuron and expiratory neuron are fired?
2 seconds inspiration
3 seconds expiration
What is VRG?
Active during forced breathing and use more muscles
If damaged, respiration ceases
How does pons contribute to the respiratory?
Makes breathing smooth
Damage will cause gasping and irregular breathing
What are other factors that affect breathing?
Stretch receptors in lungs aka hearing-Breuer reflex
Voluntary control
Chemical control - sensitivity to PCO2 is damaged then it can’t detect low pH to increase ventilation rate
Hyperventilation vs. Hypoventilation
Low arterial PCO2 -> vasoconstriction by intrinsic response causes dizziness from low O2
High arterial PCO2 -> very acidic long breath
How does one get CO poisoning?
CO binds more to hemoglobin than O2 and u run out of O2
