respiratory physiology Flashcards
1
Q
What does respiration do?
state 3 points
A
- delivers oxygen to cells for cellular respiration
- produce ATP
- remove CO2
2
Q
What are the components of respiration?
2
A
- system of pipes (conduits) = respiratory tract
- large diffusion surface area (for gas exchange) = lungs
3
Q
What is the upper respiratory tract? what are the anatomical structures associated with it?
A
anything above the vocal chords
composed of:
1. external nostril
2. nasal cavity –> nasal conchae, olfactory epithelium
3. internal nares
4. eustachian tube
5. pharynx: naso-, oro-, laryngo-
6. tonsils: pharyngeal, laryngeal, palatine
7. sinus: frontal, sphenoid
4
Q
What is the upper respiratory tract? what are the anatomical structures associated with it?
A
anything below the vocal chords
composed of:
1. epiglottis
2. cartilage: thyroid, cricoid
3. hyoid bone
4. trachea
5. carina
5. primary, secondary, tertiary bronchi
6. alveoli
5
Q
Where is the apex & base of the lungs?
A
apex = top
base = bottom
6
Q
Which lung has 3 lobes?
A
right lung
7
Q
which lung has 2 lobes?
A
left lung
8
Q
What are the two zones of the bronchial tree?
A
- Conducting zone = no gas exchange
- Respiratory zone = gas exchange
9
Q
Conducting zone of the bronchial tree
location, composition
A
location: trachea to terminal bronchioles
composition: upper regions = cartilage & smooth muscle (lined with pseudostratified ciliated columnar epithelium)
10
Q
What lines the smooth muscles in the conducting zone of the bronchial tree (upper regions)?
type of epithelium
A
psudostratified ciliated columnar epithelium
11
Q
What cells line the lower regions (walls of smaller tubes) of the bronchial tree?
A
cuboidal epithelium cells
12
Q
Does gas exchange occur in the walls of the smaller tubes ?
conducting zone
A
No
they are just pipes to bring air to the lower parts of the lungs
13
Q
What is anatomical dead space volume? Does gas exchange occur here?
A
volume of gases in upper respiratory tract and the conducting zone of the lower respiratory tract
- gas exchange does not occur here
14
Q
How much (mL) is in the anatomical dead space volume?
A
150 mL
15
Q
Respiratory zone
location, composition
A
location: respiratory bronchioles to alveolu
composition: simple squamous epithelium –> very thing
16
Q
Does gas exchange occur in the respiratory zone?
A
yes
17
Q
What composes the respiratory membrane/alveolar wall?
A
- type I alveolar cells = simple squamous epithelium
- endothelium of pulmonary capillaries
- surfactant = prevents collapse of alveoli
18
Q
What are the processes of respiration?
5 processes
A
- ventilation
- external respiration
- gas transport
- internal respiration
- cellular respiration
19
Q
Ventilation
explain what it is
A
breathing / respiration
* movement of gases between the atmosphere and the alveoli
* lungs move in response to changes in pressure (pressure gradient) in the intrapleural and intrapulmonary spaces
20
Q
Do lungs move by themselves?
A
No
* they move in response to changes in pressure
* it is the muscles attached tot he lungs that move in response to pressure
21
Q
What is the intrapulmonary space? what is the normal amount?
A
space within the lungs
10-20 mL
22
Q
What is the intrapleural space? what is the normal range?
condition
A
space between the visceral and parietal pleurae
* requires negative pressure
* 10-20 mL
23
Q
What happens when there is too much fluid in the intrapleural space?
A
pleural effusion
24
Q
What is intrapulmonary pressure? What are the normal values?
A
pressure within the lungs
at rest = 760 mmHg (atmospheric pressure)
* can change (positive or negative)
25
What is intrapleural pressure? What is the normal values?
pressure within the intrapleural space
normal = **-2 to -5 mmHg**
* **always negative**
26
What opposes lung expansion?
| 2 factors
1. elastic recoil
2. surface tension within alveoli
27
Is surface tension usually high or low within alveoli?
Normal = **low**
* due to **surfactant**
28
What cells secrete surfactant? Where are they located?
**type II epithelial/alveolar cells**
location = alveolar walls
29
Boyle's Law
| what is it?
Law that states **if temperature is held constant, the pressure of gas varies inversely with its volume**
*circumstances*:
* increase in volume = decrease in pressure (more space)
* decrease in volume = increase in pressure (mor compact)
30
Under Boyle's law, under what circumstances would **inhalation** fall under?
| talk in terms of volume and pressure
**increased volume & decreased pressure**
* inhalation follows the pressure gradient
31
Under Boyle's law, under what circumstances would **exhalation** fall under?
**decreased volume & increased pressure**
* air is leaving the body
32
What are the values of pressure **at rest**?
atmospheric pressure = 0
intrapulmonary pressure = 0
intrapleural pressure =-2
pressure gradient = 0
33
What occurs during **inspiration**? What are the values of pressure?
| during & at the end of inspiration
## Footnote
ventilation
1. **thorax expands** (intercostal muscles contract --> ribcage expands --> diaphragm gets smaller)
2. **intrapleural volume increases; intrapleural pressure decreases (-5)**
3. lung tissue is pulled outward --> **lungs are compliant** (stretchy)
4. air goes into alveoli
5. alveoli expand
6. intrapulmonary pressure returns to atmospheric
*during inspiration*:
intrapleural pressure = -5
34
Hering-Breuer Reflex
| what is it; how does it work; why is it needed
## Footnote
ventilation
**activation of stretch receptors** (in lungs, visceral pleura, and bronchioles) by **lung expansion via inspiration**
*how?* impulses are sent to the respiratory centre --> ends inspiration and starts expiration
*purpose?* prevent over-inflation of the lungs
35
What occurs during **expiration**? What are the values of pressure?
| beginning, during & at the end of expiration
## Footnote
ventilation
1.all pressure values = 0
2.**thoracic wall & lungs recoil**
3.alveoli recoil
4.**intrapulmonary volume decreases; intrapulmonary pressure increases (+)**
5.**diaphragm relaxes**
6.**air exits** the lungs
7.intrapulmonary pressure returns to 0 (atmospheric)
*during expiration*:
intrapulmonary pressure = +
36
What affects airway resistance?
| how?
**bronchiole diameter**
increased diameter --> decreases airway resistance
decreased diameter --> increases airway resistance
37
What is the equation for gas flow?
**gas flow = pressure gradient/resistance**
* increased resistance = decreased flow due to low pressure
* decreased resistance = increased flow due to high pressure
| inversely proportionate
38
What is Poiseuille's Law?
**Q = πr⁴ΔP / 8ηL**
* describes the **flow of fluid in a tube**
* states that the rate of flow of a fluid is directly proportional to the fourth power of the radius of the tube, and the pressure difference across the tube, and inversely proportional to the viscosity of the fluid and the length of the tube
NOTE: if radius is reduced by 1/2, the flow is reduced to 1/16 (example)
39
How is lung expansion maintained?
negative pressure in the intrapleural space
40
What can affect maintenance of lung expansion?
1. trauma
2. pleural effusion
3. hemothorax
4. pneumothorax (air pockets in lungs that burst spntaneously)
41
Atelectasis
| what is it? what happens?
**collapsed lung**
* occurs when there is atmospheric air in the intrapleural space
42
Spirometry
| what is it? what does it measure? what does it include?
a pulmonary function test that measures the amount and speed of air a person can inhale and exhale
43
Tidal volume (TV)
| what is it? value?
**volume of air moved into or out of the lungs** with each breath **at rest** or normal breathing
**500 mL**
44
Inspiratory reserve volume (IRV)
| what is it? value?
volume of air that can be **forcibly inspired above tidal volume**
* represents the air that can that can be inhaled to increase the amount of oxygen available in the lungs
**2100-3200 mL**
45
Expiratory reserve volume (ERV)
| what is it? value?
volume of air that can be **forcibly expired/exhaled above tidal volume**
* the additional volume of air that a person can exhale beyond the amount exhaled during a normal breath.
**1000-1200 mL**
46
Residual volume (RV)
| what is it? value?
volume of air **remaining** in lungs **after maximal forced exhalation**
**about 1200 mL**
47
Vital capacity
| what is it? value?
**volume of air** that can be **expired after maximum inspiration**
**about 4800 mL**
48
Total lung capacity (TLC)
| what is it? value?
**TV + IRV + ERV + RV**
**6000 mL**
49
Forced Expiratory Volume (FEV1)
| what is it? value?
**volume of air** that can be **forcibly exhaled in 1 second (after maximum inhalation)**
**70-80% of forced vital capacity (FVC)**
50
External respiration
| what is it? where does it occur?
**diffusion of gases** between the **alveolar air and the blood**
*location*: alveoli
51
What factors determine diffusion?
| 5 factors
1. ventilation-perfusion ratio
2. surface area for diffusion
3. partial pressure of gases
4. solubility of gases
5. thickness of the diffusion membrane
52
Ventilation-Perfusion (VQ) scan
| normal values?
## Footnote
diffusion factors
measure of **efficiency of gas exchange** in the lungs
Ventilation = air flow
Perfusion = blood flow
ideal/normal = **1:1**
53
Surface area for diffusion
| normal value? what is it?
## Footnote
diffusion factor
normal = **70 m^2**
* may be reduced by diseases (emphysema, pulmonectomy)
* larger surface area = more diffusion
54
Partial pressures
| what is it? what is the significance
## Footnote
diffusion factor
portion of the **total pressure exerted by each individual gas** in a mixture of gases
* directs the movement of gas exchange
55
Henry's Law
| partial pressure
## Footnote
diffusion factor
A **gas in contact with a liquid** will **dissolve in the liquid** in **proportion to its partial pressure and solubility**
56
Dalton's Law
| partial pressure
## Footnote
diffusion factor
the **total pressure exerted by a mixture of gases = sum of the individual pressures exerted independently** by each gas in the mixtue
57
Composition & partial pressure of **atmospheric air**
## Footnote
diffusion factors
composition:
1. N2 = 79%
2. O2 = 21%
3. CO2 = 0.04%
4. H2O = 0%
partial pressures: (X760)
1. PN2 = 600 mmHg
2. PO2 = 159 mmHg
3. PCO2 = 0.3 mmHg
4. PH2O = 0 mmHg
NOTE: total should equal 760 mmHg
58
Composition & partial pressure of **alveolar air**
## Footnote
diffusion factors
composition:
1. N2 = 74.9%
2. O2 = 13.6%
3. CO2 = 5.3%
4. H2O = 6.2%
partial pressures: (X760)
1. PN2 = 569 mmHg
2. PO2 = 104 mmHg
3. PCO2 = 40 mmHg
4. PH2O = 47 mmHg
NOTE: total should equal 760 mmHg
59
Partial pressures of **deoxygenated blood gases**
| values? where?
## Footnote
diffusion factor
**PVO2 = 40 mmHg
PVCO2 = 45 mmHg**
location: mostly in **veins** except for pulmonary system
60
Partial pressures of **oxygenated blood gases**
## Footnote
diffusion factor
**PVO2 = 104 mmHg
PVCO2 = 40 mmHg**
location: mostly in **arteries** except for pulmonary system
61
Gas Transport
| what is it?
transport of gases through the circulatory system
62
How is oxygen transported?
| percentage?
**98.5%** bound to hemoglobin (heme) = **oxyhemoglobin**
1.5% = dissolved in plasma
63
How is carbon dioxide transported?
| gas transport
**70% = bicarbonate ion**
20% = bound to hemoglobin (carbaminohemoglobin)
7-8%= dissolved in plasma
64
Internal Respiration
| what is it?
exchange of gases (oxygen and carbon dioxide) between the **cells and the bloodstream** within an organism
*in tissues*: gases move between blood and the interstitial fluid via capillary walls
* follows pressure gradient --> similar to movement between air and blood
65
Cellular respiration
**Glucose + O2 --> CO2 + H2O + ATP + heat**
*location*: mitochondria
*purpose*: provides cell with energy
66
How is respiration controlled?
| explain
## Footnote
control of respiration
**Neural regulation**
* **chemoreceptors** = sense blood chemistry --> **H+** ion concentration and **PCO2**
67
Central chemoreceptors
| location? what do they respond to?
*location*: **brainstem**
*function*: responds to **CSF changes in PCO2 and pH**
68
Effects of low pH
| what happens with central chemoreceptors?
low pH:
* activates central chemoreceptors
* stimulates respiratory control center
* **hyperpnea** = increase rate and depth of breathing
69
Peripheral chemoreceptors
| location? fucntion?
*location*: carotid sinuses and aortic bodies
*function*: responds to **increase PCO2; low pH** & **extreme decrease in PO2 (< 70 mmHg)**
70
what happens when there is an increase PCO2; low pH & extreme decrease in PO2 (< 70 mmHg) ?
| what happens with the peripheral chemoreceptors?
**increase PCO2; low pH & extreme decrease in PO2 (< 70 mmHg)**:
* stimulation of peripheral chemoreceptors
* sends impulses to the repsiratory centers
* increases ventilation
71
What is the most powerful stimuli of the respiratory system?
increase in H+ ions & increased PCO2
72
What 2 centres contribute to the motor control of ventilation?
1. **Medullary rhythmicity area** =inspiratory and expiratory centres
2. **Pons centre** = apneustic and pneumotoxic centres
73
Medullary centres
| what is it? function?
## Footnote
motor control of ventilation
**Rhythmicity centre**
* neurons depolarize spontaneously & rhythmically
* achieves **eupnea** = normal breathing
* sends **motor impulses to muscles of inspiration**
1. inspiratory centre = via **phrenic nerves** --> to the **diaphragm**
2. expiratory centre = via **intercosal nerves** --> to **intercostal muscles**
74
What are the two centres of the medullary centres?
1. inspiratory center
2. expiratory center
75
Pons centers
| what is it? function? types?
## Footnote
motor control of ventilation
**pneumotaxic centre** = shortens period of inspiration --> prevent overinflation
**apneustic centre** = prolongs period of inspiration --> inhibited by feedback from lungs
76
What are the higher centers?
## Footnote
motor control of ventilation
1. cerebral cortex
2. hypothalamus
77
Cerebral cortex
## Footnote
motor control of ventilation
* limited voluntary control
* emotions trigger influence via limbic system and hyptohalamus
78
# Effect of:
Acid-Base Imbalance
**changes in rate and depth of respiration**
* even if PCO2 and PO2 remain unchanged, a change in pH will always trigger chnages in respiration
79
# Effect of:
Low pH
## Footnote
acid-base balance
low pH leads to:
* increased CO2 in blood (acidic) = **metabolic acidosis**
* **hyperapnea** = increase in respiratory rate, effort & depth --> **eliminates CO2**
80
# Effect of:
High pH
## Footnote
acid-base balance
high pH leads to:
* decreased CO2 in blood = **alkalosis**
* **hypoapnea** = decrease in respiratory rate, effort & depth --> **retains CO2**
