Chapter 16 Flashcards
Internal respiration
Oxidative phosphorylation
External respiration
Pulmonary ventilation
* Exchange between lungs and blood
* Transportation in blood
* Exchange between blood and body tissues
Air passages of the head and neck
- Nasal cavities
- Oral cavity
- Pharynx
Label figure 16.2
What figures are apart of the conducting zone?
Larynx
* Glottis
* Epiglottis
* Trachea
* Bronchi
Bronchioles
Secondary bronchi
- Three on right side to three lobes of right lung
- Two on left side to two lobes of left lung
Tertiary bronchi
20-23 orders of branching
Bronchioles
less than 1mm in diameter
Terminal Bronchioles
Functions of the conducting zone
- Air passageway: 150 mL in volume (dead space)
- Increases air temperature to body temperature
- Humidifies air
Epithelium of the conducting zone
- Goblet cells (secrete mucus)
- Ciliated cells (move particles toward mouth)
- Mucus escalator
Function of the respiratory zone
- Exchange of gases between air and blood
- Mechanism of action: diffusion
Structures of the respiratory zone
- Respiratory bronchioles
- Alveolar ducts
- Alveoli
- Alveolar sacs
Epithelium of the respiratory zone
- Epithelial cell layer of alveoli
- Endothelial cell layer of capillaries
Alveoli
Site of gas exchange
Rich blood supply: capillaries form sheet over alveoli
Alveolar pores
type 1 and type 2
Type I alveolar cells
make up wall of alveoli
* Single layer of epithelial cells
Type II alveolar cells
secrete surfactant
Respiratory membrane
- Barrier for diffusion
- Type I cells + basement membrane
- Capillary endothelial cells + basement membrane
Chest wall
airtight, protects lungs
What composes the chest wall
- Rib cage
- Sternum
- Thoracic vertebrae
- Muscles: internal and external intercostals, diaphragm
Pleura
membrane lining of lungs and chest wall
What surrounds each lung?
pleura
Intrapleural space is filled with?
intrapleural fluid (15ml)
Label figure 16.7
Air moves in and out of lungs by
bulk flow
Air moves from
high to low pressure
Inspiration
pressure in lungs less than atmospheric
pressure
Expiration
pressure in lungs greater than atmospheric
pressure
Atmospheric pressure
- 760 mm Hg at sea level
- Decreases as altitude increases
- Increases under water
Intra-alveolar pressure
- Pressure of air in alveoli
- Given relative to atmospheric pressure
- Varies with phase of respiration
During inspiration what is intra-alveolar pressure?
negative (less than atmospheric)
During expiration what is intra-alveolar pressure?
positive (more than atmospheric)
Difference between Palv and Patm drives?
ventilation
Intrapleural pressure
Pressure inside pleural sac
* Always negative under normal conditions
* Always less than Palv
Intrapleural pressure varies with?
respiration
at rest, -4 mm Hg
Why is intraplearal pressure negative?
Negative due to elasticity in lungs and chest wall
* Lungs recoil inward as chest wall recoils outward
* Opposing forces pull on intrapleural space
* Surface tension of intrapleural fluid prevents wall and lungs from
pulling apart
Transpulmonary pressure
= Palv – Pip
* Distending pressure across the lung wall
Increase in transpulmonary pressure
- Increases distending pressure across lungs
- Causes lungs (alveoli) to expand, increasing volume
Movement of air in and out of lungs occurs due to
pressure gradients
Mechanics of breathing describes mechanisms for
creating pressure gradients
Boyle’s law
pressure is inversely related to volum
Flow =
Patm - Palv / R
alveolar pressure changes affect and can be affected by?
gradients ; volume
Factors determining intra-alveolar pressure
- Quantity of air in alveoli
- Volume of alveoli
when lungs expand….
alveolar volume increases
* Palv decreases
* Pressure gradient drives air into lungs
when lungs recoil….
alveolar volume decreases
* Palv increases
* Pressure gradient drives air out of lungs
Inspiratory muscles increase
volume of thoracic
cavity
* Diaphragm
* External intercostals
Expiratory muscles decrease
volume of thoracic
cavity
* Internal intercostals
* Abdominal muscles
label figure 16.11
Inspiration steps
- Neural stimulation of inspiratory muscles
- Diaphragm contraction causes it to flatten and move downward
- Contraction of external intercostals makes ribs pivot upward and
outward, expanding the chest wall - Collectively, thoracic cavity volume increases
- Outward pull on pleura decreases intrapleural pressure, which
results in an increase in transpulmonary pressure - Alveoli expand, decreasing alveolar pressure
- Air flows into alveoli by bulk flow
Figure 16.12 easier
Expiration is what type of process
passive process
When inspiratory muscles stop contracting….
recoil of the
lungs and chest wall to their original positions decreases
the volume of the thoracic cavity
Active expiration requires?
expiratory muscles
Contraction of expiratory muscles creates
a greater and
faster decrease in the volume of the thoracic cavity
Lung compliance
Ease with which lungs can be stretched
Lung compliance formula
^V / ^ (Palv - Pip)
Larger lung compliance
- Easier to inspire
- Smaller change in transpulmonary pressure
needed to bring in a given volume of air
Factors affecting lung compliance
- Elasticity
- Surface tension of lungs
More elasticity =
less compliance
Surface tension
force for alveoli to collapse
or resist expansion
Surface tension arises due to
attractions between water
molecules
Greater tension =
less compliance
To overcome surface tension what do the lungs do?
secrete sufactant from type II cells
Surfactant
detergent that decreases surface tension
Surfactant increases
lung compliance
* Makes inspiration easier
As airways get smaller in diameter…
they increase
in number, keeping overall resistance low
Increase in resistance makes it ….
harder to breathe
Bronchoconstriction
smooth muscle contracts, causing
radius to decrease
Bronchodilation
smooth muscle relaxes, causing radius
to increase
Contractile state of bronchiolar smooth muscle under what control?
extrinsic and intrinsic control
Sympathetic role in bronchiole radius
- Relaxation of smooth muscle
- Bronchodilation
parasympathetic role in bronchiole radius
- Contraction of smooth muscle
- Bronchoconstriction
Extrinsic control of bronchiole radius
Hormonal control
* Epinephrine
* Relaxation of smooth muscle
* Bronchodilation
Intrinsic control of bronchiole radius
Histamine and CO2
Histamine
bronchoconstriction
* Released during asthma and allergies
* Also increases mucus secretion
CO2
bronchodilation
Pathological states that increase airway resistance
Asthma and COPD
Tidal volume (VT)
500 mL
* Single, unforced breath
Inspiratory reserve volume (IRV):
3000 mL
* After breathing in, volume you can still inspire
Expiratory reserve volume (ERV):
1000 mL
* After breathing out, volume you can still expire
Residual volume (RV)
1200 mL
* Volume left after ERV
* Measurable by helium dilution method
Inspiratory capacity (IC) =
VT + IRV = 3500 mL
Vital capacity (VC)
maximum volume expired after
maximum inspiration
* VC = VT + IRV + ERV = 4500 mL
Functional residual capacity (FRC)
volume remaining
after resting tidal volume
* FRC = ERV + RV = 2200 mL
Total lung capacity (TLC)
volume air in lungs after
maximum inspiration
* TLC = VT + IRV + ERV + RV = 5700 mL
Obstructive pulmonary diseases
- increased airway resistance
- Residual volume increases (making it more difficult to
expire) - Functional residual capacity increases
- Vital capacity decreases
Restrictive pulmonary diseases
- More difficult for lungs to expand
- Total lung capacity decreases
- Vital capacity decreases
Forced vital capacity (FVC)
maximum-volume inhalation
followed by exhalation as fast as possible
* Low FVC indicates restrictive pulmonary disease
Forced expiratory volume (FEV)
- percentage of FVC that
can be exhaled within certain time frame - Normal FEV1 = 80%
- FEV1 < 80% indicates obstructive pulmonary disease
Peak expiratory flow rate (PEFR)
maximum rate
at which a person can exhale
* Men = 9 L/sec
* Women = 7 L/sec
Minute ventilation
total volume of air entering
and leaving the respiratory system each minute
Minute ventilation formula
- Minute ventilation = VT x RR
- Normal respiration rate = 12 breaths/min
- Normal VT = 500 mL
- Normal minute ventilation =
500 mL 12 breaths/min = 6000 mL/min
Anatomical dead space
- Air in conducting zone does not participate
in gas exchange - Conducting zone = anatomical dead space
Alveolar ventilation
- Volume of air reaching the gas exchange areas
per minute - Alveolar ventilation = (VT × RR) – (DSV × RR)
