Respiratory System Flashcards
cells produce energy
for maintenance, growth, defense, and division
through mechanisms that use oxygen and produce carbon dioxide
oxygen
is obtained from the air by diffusion across delicate exchange surfaces of lungs
is carried to cells by the cardiovascular system which also returns carbon dioxide to the lungs
functions of the respiratory system
external respiration
acid-base balance
produces sounds for communication
provide olfactory sensation=smell
blood pressure regulation (synthesis of Angiotensin 2)
protects respiratory surfaces from outside environment
external respiration
provides extensive gas exchange surface area between air and circulating blood (O2 and CO2)
acid-base balance
influences pH of body fluids by elimination of CO2
protects respiratory surfaces from outside environment
dehydration, temperature changes, invasion by pathogens
principal organs of the respiratory system
nose, pharynx, larynx, trachea, bronchi, lungs
the respiratory system is divided into
the upper respiratory system, above the larynx
the lower respiratory system, from the larynx down
upper respiratory system
function to warm and humidify air
nose, nasal cavity, sinuses, pharynx- naso, oro and laryngo
lower respiratory system
conduction portion and respiratory portion
conduction portion
bring air to respiratory surfaces
larynx, trachea, bronchi, bronchioles
respiratory portion
gas exchange
alveoli
alveoli
are air-filled pockets within the lungs
where all gas exchange takes place
the respiratory mucosa
consists of an epithelial layer and an areolar layer called the lamina propria
lines the conducting portion of respiratory system
structure of respiratory epithelium
pseudostratified ciliated columnar epithelium with numerous mucous cells- nasal cavity and superior portion of the pharynx
stratified squamous epithelium- inferior portions of the pharynx
pseudostratified ciliated columnar epithelium- superior portion of the lower respiratory system
cuboidal epithelium with scattered cilia- smaller bronchioles
alveolar epithelium
is a very delicate, simple squamous epithelium
contains scattered and specialized cells
lines exchange surfaces of alveoli
lamina propria
underlying layer of areolar tissue that supports the respiratory epithelium
in the upper respiratory system, trachea, and bronchi- it contains mucous glands that secret onto epithelial surface
in the conducting portion of lower respiratory system- it contains smooth muscle cells that encircle lumen of bronchioles
the respiratory defense system
consists of a series of filtration mechanisms
removes particles and pathogens
components of the respiratory defense system
- filtration in nasal cavity removes large particles
- mucus- from goblet cells and glands in lamina propria traps foreign objects
- cilia “mucus escalator”- move carpet of mucus with trapped debris out of the respiratory tract
- alveolar macrophages- phagocyte particles that reach alveoli
disorders of the respiratory defense system
- cystic fibrosis caused by failure of mucus escalator, results in thick mucus which blocks airways and encourages bacteria growth
- smoking-> destroys cilia
- inhalation of irritation-> chronic inflammation-> cancer e.g. squamous cell carcinoma
the nose
only external feature
air enters the respiratory system through external nares into nasal vestibule
space in flexible part, lined with hairs to filter particles, leads to nasal cavity
nasal hairs in nasal vestibule are the first particle filtration system
the nasal cavity
the nasal septum divides nasal cavity into left and right
superior portion of nasal cavity is the olfactory epithelium-> provides sense of smell
nasal conchae (superior, middle, inferior) project into cavity on both sides
hard and soft palate
air flow-> nasal cavity opens into nasopharynx through internal nares
nasal conchae
causes air to swirl
1. increase likelihood of trapping foreign material in mucus
2. provide time for smell detection
3. provide time and contact to warm and humidify air
hard palate
forms floor of nasal cavity
separates nasal and oral cavities
soft palate
extends posterior to hard palate
divides superior nasopharynx from lower pharynx
nose and nasal cavity
opening airway for respiration
moisten and warm entering air
filter and clean inspired air
resonating chamber for speech
houses olfactory receptors
the pharynx
a chamber shared by digestive and respiratory systems
extends from internal nares to entrances to larynx and esophagus
three parts: nasopharynx, oropharynx, laryngopharynx
nasopharynx
air only
posterior to nasal cavity
pseudostratified squamous columnar epithelium
closed off by soft palate and uvula during swallowing
pharyngeal tonsil located on posterior wall
inflammation can block airway
auditory tubes open here
oropharynx
food and air
posterior to oral cavity
stratified squamous epithelium
palatine and lingual tonsils in mucosa
laryngopharynx
lower portion
stratified squamous epithelium
continuous with esophagus
air flow from the pharynx enters
the larynx
what is the larynx
a hyaline cartilage structure that surrounds the glottis
opening form laryngopharynx to trachea
contains epiglottis- elastic cartilage flap-> covers glottis during swallowing
functions of larynx
provide continuous airway
act as switch to route food and air properly
voice production
larynx
voice box
folds of epithelium over ligaments of elastic fibers create vocal folds/cords
vocal cords project to glottis
air passing through glottis vibrates folds producing sound
pitch-> controlled by tensing/relaxing of the cords- tense + narrow = high pitch
volume-> controlled by the amount of air
sound production-> phonation
speech
formation of sound using mouth and tongue with resonance in pharynx, mouth, sinuses and nose
laryngitis
inflammation of vocal folds
cause-> infection or overuse that can inhibit phonation
the trachea
attached to inferior of larynx
walls composed of three layers: mucosa, submucosa, adventitia
mucosa
pseudostratified columnar epithelium, goblet cells, lamina propria, smooth muscle and glands
submucosa
connective tissue (CT) with additional mucus glands
adventitia
CT with hyaline cartilage rings (15-20)-> keep airway open, C-shaped
opening toward the esophagus to allow expansion, ends connected by trachealis muscle
primary bronchi organization
trachea branches into the right and left primary bronchi
similar structure as trachea- no trachealis muscle
right= steeper angle
enter lungs at groove (hilum)- along with blood and lymphatic
primary bronchi
lungs have lobes separated by deep fissures
inside lungs bronchi branch, get smaller in diameter- branch ~23 times creating the bronchial tree
as bronchi get smaller, structure changes
less cartilage in adventitia
more smooth muscle in lamina propria
epithelium is thinner, less cilia, less mucus
hilum
where pulmonary nerves, blood vessels, and lymphatics enter lung
anchored in meshwork of connective tissue
bronchitis
inflammation of bronchial walls: causes constriction and breathing difficulty
the lungs
left and right lungs- are in left and right pleural cavities
the base- inferior portion of each lung rests on superior surface of diaphragm
lobes of the lungs are separated by deep fissures- right has 3, left has 2
pleurisy
inflammation of pleura
restrict movement of lungs-> breathing difficulty
terminal bronchiole
smallest bronchi
no cartilage
last part of conduction portion
trachea, bronchi and bronchioles innervated by ANS to control airflow to the lungs
ANS regulates smooth muscle
controls diameter of bronchioles
controls airflow and resistance in lungs
sympathetic-> bronchodilation
parasympathetic-> bronchoconstriction- histamine release (allergic reactions)
asthma
excessive stimulation and bronchoconstriction
activated by inflammatory chemicals (histamine)
stimulation severely restricts airflow
epinephrine inhaler mimics sympathetic ANS-> bronchodilation
terminal bronchiole branching
each terminal bronchiole delivers air to one pulmonary lobule, separated by CT
inside lobule, terminal bronchiole branches into respiratory bronchioles- no cilia or mucus
each respiratory bronchiole connects to alveolar sac made up of many alveoli
alveoli
wrappe in capillaries
held in place by elastic fiber
three cell types: type 1 cells, type 2 cells, alveolar macrophages
type 1 cells
gas exchange
simple squamous epithelium, lines inside
type 2 cells
surfactant
cuboidal cells produce surfactant
phospholipids + proteins
prevent alveolar collapse, reduces surface tension
alveolar macrophages
phagocytosis of particles
respiratory distress
difficult respiration due to alveolar collapse caused when septal cells do not produce enough surfactant
disorders of the alveoli
pneumonia
pulmonary embolism
pneumonia
inflammation of lungs from infection or injury
causes fluid to leak into alveoli
compromises function of respiratory membrane-> prevents gas exchange
pulmonary embolism
block in branch of pulmonary artery
reduce blood flow
causes alveolar collapse
external respiration
includes all processes involved in exchanging O2 and CO2 with the environment
internal respiration
also called cellular respiration
involves the uptake of O2 and production of CO2 within individual cells
three processes of external respiration
- pulmonary ventilation (breathing)
- gas diffusion- across membranes and capillaries
- transport of O2 and CO2- between alveolar capillaries and between capillary beds in other tissues
breathing
repetitive cycle of inspiration (inhaling) and expiration (exhaling)
respiratory cycle
one complete breath, inspiration and expiration
quiet respiration
breathing while at rest; effortless and automatic
forced respiration
deep or rapid breathing, such as during exercise or playing an instrument
pressure difference
flow of air in and out of lung depends on a pressure difference between air within lungs and outside body
respiratory muscles
change lung volumes and create differences in pressure relative to the atmosphere
pulmonary ventilation
is the physical movement of air into/out of respiratory tract- provides alveolar ventilation
visceral pleura adheres to parietal pleura via surface tension- altering size of pleural cavity will alter size of lungs
injury to chest wall
pneumothorax- allows air into pleural cavity
atelectasis (also called a collapsed lung) is a result of pneumothorax
Boyle’s law
gas pressure is inversely proportional to volume
defines the relationship between gas pressure and volume: P=1/V
pressure and airflow to the lungs
air flows from area of higher pressure to area of lower pressure
mechanism of pulmonary ventilation
causes volume changes that create changes in pressure
volume of thoracic cavity changes- with expansion or contraction of diaphragm or rib cage
diaphragm contraction
contraction of diaphragm pulls it toward abdomen- lung volume INCREASE, air pressure DECREASE, air flows in
diaphragm relaxation
causes diaphragm to rise in dome shape
lung volume DECREASE
air pressure INCREASE
air flows out
rib cage
movements can contribute
superior = bigger, air in
inferior = smaller, air out
factors influencing pulmonary ventilation
- airway resistance
- compliance (ability of lungs and thorax to expand)
airway resistance
diameter of bronchi
obstructions
compliance (ability of lungs and thorax to expand)
effort required to expand lungs and chest
high compliance = expand easily, normal
low compliance = resist expansion
compliance affected by
- CT structure
- alveolar expandability
- mobility of thoracic cage
CT structure
loss of elastin/replacement by fibrous tissue = decrease compliance
emphysema- respiratory surface replaced by scars, loss of surface for gas exchange, decrease elasticity = decrease compliance
alveolar expandability/alveolar surface tension
surfactant (type 2 cells) reduces alveoli surface tension allow inflation
respiratory distress syndrome- too little surfactant-> requires great force to open alveoli to inhale- increase surface tension (decrease surfactant)= decrease compliance- fluid (edema) = decrease compliance
mobility of thoracic cage
less mobility = decrease compliance
quiet breathing inspiration
eupnea
diaphragm: moves 75% of air
external intercostals: elevate ribs, 25% more
forced breathing inspiration
hyperpnea
maximum rib elevation increases respiratory volume 6x
serratus anterior, pectoralis minor, scalenes, sternocleidomastoid
inspiration
inhalation involves contraction of muscles to increase thoracic volume
quiet breathing
eupnea
passive, muscles relax, thoracic volume decrease
forced breathing
hyperpnea
abdominal muscles (obliques, transversus, rectus) contract forcing diaphragm up, thoracic volume further decrease
resting tidal volume (TV)
the amount of air inhaled or exhaled with each breath under resting conditions
expiratory reserve volume (ERV)
amount of air that can be forcefully exhaled after a normal tidal volume exhalation
inspiratory reserve volume (IRV)
amount of air that can be forcefully inhaled after a normal tidal volume inhalation
residual volume (RV)
amount of air reaming in the lungs after a forced exhalation
inspiratory capactiy (IC)
maximum amount of air that can be inspired after a normal expiration
IC= tidal volume + IRV
functional residual capacity (FRC)
volume of air remaining in the lungs after a normal tidal volume expiration
FRC= ERV + RV
vital capacity
maximum amount of air that can be expired after a maximum inspiratory effort
VC = TV + IRV + ERV
total lung capacity
maximum amount of air contained in lungs after a maximum inspiratory effort
TLC = TV + IRV + ERV + RV
a breath
one respiratory cycle
respiratory rate
breaths/min
at rest ~12-20
respiratory minute volume
(RMV/MRV) amount of air moved per minute; measures pulmonary ventilation
respiratory rate x tidal volume, ~6 L
anatomic dead space
air remains in conduction portions
~1 ml/lb body weight
alveolar ventilation
air reaching alveoli/min
at rest ~4.2 L
both tidal volume and respiratory rate
adjusted to meet oxygen demands of body
composition of air
nitrogen (N2) about 79%
oxygen (O2) about 21%
water vapor (H2O) about 0.5%
carbon dioxide (CO2) about 0.04%
trace inert gasses
partial pressure of gas
concentration in air
gas exchange depends on
- partial pressures of the gases
- diffusion/concentration gradients
partial pressures of the gases
the pressure contributed by each gas in the atmosphere
all partial pressures together add up to 760 mm Hg- also known as atmospheric pressure
diffusion/concentration gradients
gasses follow diffusion/concentration gradients to diffuse into liquid
rate depends on partial pressure and temperature
Henry’s law
the amount of dissolved gas in a liquid is directly proportional to its partial pressure
efficiency of gas exchange/diffusion at the respiratory membrane due to
- substantial differences in partial pressure across the respiratory membrane
- distances involved in gas exchange are small
- O2 and CO2 are lipid soluble
- total surface area for diffusion is large
- coordination of blood and air flow- increase blood to alveoli with increase O2
gas exchange in lungs
PP O2- high in alveoli and low in capillary (blood)- diffuse into capillaries
PP CO2- low in alveoli and high in capillary (blood)- diffuse into alveoli
gas exchange in tissues
pressure and flow reversed
O2 into tissues
CO2 into capillary
gas exchange high altitude sickness
decrease PP O2 at high altitude-> decrease diffusion into blood
decompression sickness
PP of air gasses high underwater
high amounts of N2 diffuses in blood
if pressure suddenly decreases- N2 leaves blood as gas causing bubbles-> damage and pain
hyperbaric chambers are used to treat
transport of oxygen
1.5% dissolved in plasma
most bound to iron ions on heme of hemoglobin in erythrocytes
4 O2/HB, ~280 million Hb/RBC ~1 billion O2, RBC
hemoglobin saturation
% of hemes bound to O2
~97.5 at alveoli
at high PP O2 hemoglobin binds O2
at low PP O2 hemoglobin releases O2
carbon monoxide poisoning (CO)
compete O2 for binding to Hb, even at low PP CO
causes suffocation (no O2)
other factors that affect Hb saturation
Bohr effect
temperature
BPG
pregnancy
Bohr effect
affect of pH
Hb releases O2 in acidic pH
high CO2 creates carbonic acid
temperature
Hb releases O2 in high temperature
BPG (2,3 biphosphoglycerate)
produced by healthy RBC during glycolysis
increase BPG= increase O2 release
pregnancy
fetal Hb= increase O2 binding
fetal and adult hemoglobin
the structure of fetal hemoglobin differs from that of adult Hb
at the same PO2
fetal Hb binds more O2 than adult Hb
which allows fetus to take O2 from maternal blood
hemoglobin in RBCs
carries most blood oxygen
releases it in response to low O2 partial pressure in surrounding plasma
if PO2 increases
hemoglobin binds oxygen
if PO2 decreases
hemoglobin releases oxygen
at a given PO2
hemoglobin will release additional oxygen
if pH decreases or temperature increases
transport of carbon dioxide
~70% as carbonic acid
in RBCs and plasma carbonic anhydrase in RBCs catalyze reaction with water
~23% as carbaminohemoglobin- CO2 bound to amino groups of Hb
~7% dissolved in plasma as CO2
respiratory homeostasis requires that
diffusion rates at peripheral capillaries (O2 in, CO2 out) and alveoli (CO2 out, O2 in) must match
regulation
autoregulation
neural regulation
autoregulation
lung perfusion
alveolar ventilation
lung perfusion
blood flow in lungs is redirected to alveoli with high partial pressure of O2
alveolar ventilation
alveoli with high partial pressure of CO2 receive increased air flow
respiratory rhythmicity centers
located in the medulla oblongata
control the basic pace and depth of respiration
respiratory centers
located in the pons
apneustic center
pneumotaxic center
apneustic center
stimulated centers in medulla for inhalation
pneumotaxic center
inhibits the apneustic center to allow expiration
modifies the pace set by the respiratory centers in medulla
respiratory reflexes
respiratory centers modify activity based on input from receptors
chemoreceptors
baroreceptors
stretch receptors
pulmonary irritant receptors
other
chemoreceptors
monitor CO2, O2, and pH in blood and CSF
baroreceptors
monitor blood pressure in aorta and carotid artery
stretch receptors
monitor inflation of the lungs (Hering-Breuer reflex)
pulmonary irritant receptors
monitor particles in respiratory tracts and trigger cough or sneeze
other
pain, temperature, and visceral sensations can trigger respiratory reflexes
effects of aging on the respiratory system
- elastic tissues deteriorate- reducing lung compliance, lowering vital capacity
- arthritic changes in rib cage- decrease mobility of chest movements, decrease respiratory minute volume
- emphysema- decrease gas exchange, higher risk if exposed to respiratory irritants (ex. cigarette smoke, dusty jobs)
