Respiratory System Flashcards
3 steps to respiration
pulmonary ventilation
external respiration
internal respiration
pulmonary ventilation
aka breathing
movement of air into and out of the lungs
external respiration
gas exchange b/w air in lungs and blood (to/from external env’t)
- also includes transport of oxygen and carbon dioxide through the blood
internal respiration
gas exchange between blood and tissues of the body
respiratory system functions
- regulation of blood pH
- production of chemical mediators
- voice production
- olfaction
- protection
regulation of blood pH
bicarbonate system alters blood pH by changing blood CO2 levels and producing/removing H+ ions
production of chemical mediators
ACE: angiotensin converting enzyme is produced by the lungs
voice production
movement of air past vocal folds makes sound and speech
olfaction
smell occurs when airborne molecules are drawn into nasal cavity
protection
against microorganisms by preventing entry and removing them from respiratory surfaces (found from nasal passages through to alveoli in the lungs)
upper vs lower respiratory systems
upper: nasal cavity, nose, pharynx
lower: larynx, trachea, bronchi, lungs
conducting zones
movement of air but no gas exchange occurs here
respiratory zones
gas exchange occurs here
ie. only really includes the alveoli
olfactory epithelium
found in roof of nasal cavity and contributes to sense of smell
histology of nasal cavity
pseudostratified ciliated columnar with goblet cells lines nasal cavity
- warms air (highly vascular)
- mucous moistens air and traps dust
- cilia move mucous towards pharynx
nasal vestibule
contains stratified squamous epithelium and is lines with nasal hairs
choana
internal naris (end of nasal cavity)
nasal conchae
ridges in naris create turbulent air
- are superior, middle and inferior
nasal meatuses
- canals between conchae where air actually moves
- have superior, middle and inferior ones
- lacrimal duct carries into inferior meatus and also adds moisture to air
sinuses
small cavities in the bone
paranasal sinuses
composed of frontal sinus and sphenoidal sinus
- lined with mucous membrane and makes skull lighter
- also helps resonate sounds in voice production
hard palate
composed of maxilla and palatine bone
pharynx
13cm long muscular tube composed of skeletal muscle and mucous membranes
- extends from choaneae to opening of esophagus
functions include:
- passage for food, air
- resonating chamber for speech production
- tonsils are masses of lymphatic tissue that have immunological functions
regions of the pharynx
nasopharynx
oropharynx
laryngopharynx
nasopharynx
posterior to choanae, and superior to soft palate
- passageway for air only
- pseudostratified ciliated columnar epithelium
oropharynx
soft palate to epiglottis
- common passageway for air and food
- stratified squamous epithelium
laryngopharynx
epiglottis to esophagus
- common passageway for air and food
- stratified squamous epithelium
soft palate
a little muscle and mucous membrane
- moves upward to close off nasal cavity when swallowing
fauces
opening of oral cavity into oropharynx
glottis
controls opening of vocal folds which can stop materials from entering the trachea
larynx
composed of 9 pieces of cartilage
- 3 are unpaired, 6 are in pairs, some attach to hyoid bone
epiglottis
leaf shaped piece of elastic cartilage
- during swallowing, larynx moves upward and epiglottis bends to cover glottis
thyroid cartilage
forms adam’s apple
cricoid cartilage
ring of cartilage attached to top of trachea
cuneiform cartilage
embedded in mucous membranes of epiglottis
arytenoid cartilage
articulates with corniculate cartilage
- moves and changes shape and tension of vocal folds
vestibular fold
false vocal fold
- more superior
- doesn’t actually change shape, stays open
vocal fold
true vocal fold
- creates vibrations in the air as air passes them
- abduction moves vocal folds apart for breathing
- adduction involves medial rotation of arytonoid cartilage which moves vocal folds together
trachea
12 cm long
- extends from larynx (cricoid cartilage) to T5 vertebrae
- 16-20 C shaped rings of hyaline cartilage support dense regular CT and smooth muscle, prevents trachea from collapsing
- the open part on posterior side is to accomodate the esophagus (elastic membrane and trachealis muscle)
- thyroid wraps around trachea somewhat
histology of trachea
pseudostratified ciliated columnar epithelium with goblet cells propel particulate matter towards the pharynx
tracheobronchial tree
approximately 16-18 divisions
- progressive loss of cartilage replaced with plates of cartilage and then smooth muscle
- trachea bifurcates (carina) resulting in primary bronchi, then secondary bronchi (lobar bronchus) to tertiary bronchi (right or left segmental bronchus)
carina
bifurcation of trachea, very sensitive and if debris touches it, it initiates cough reflex to keep it from entering the lungs
lung general anatomy
base, apex, hilum, lobes defined
base: sites on diaphragm
apex: pointed portion at the top of the lungs
hilum: medial surface where bronchi and blood vessels enter the lungs (aka root of the lungs)
lobes of the lungs: each are separated by secondary bronchi
fissures of the lungs
oblique fissure: runs between superior and inferior lobes
horizontal fissure: separates superior and middle lobe (right lung only)
differences in the R and L lungs
right lung: has 3 lobes (superior, middle, inferior) separated by oblique and horizontal fissures
left lung: has 2 lobes (superior and inferior) separated by oblique fissure
cardiac notch
indentation in left lung to accommodate heart
cardiac impression
where the heart sits on the medial side of the left lung
pleural fluid
in pleural cavity (serous membrane that surrounds the lungs)
- reduces friction
- holds parietal and visceral pleura together
terminal bronchiole
where gas exchange can actually occur
- lined with smooth muscle
what are alveolar walls composed of?
type I and type II alveolar cells
type I alveolar cells
pneumocytes
- flat cells, that allow a thin layer for gas exchange to occur
type II alveolar cells
aka septal cells
pneumocytes also
- more round, secrete alveolar fluid that contains surfactant (a compound that reduces surface tension)
- line inside lumen of alveolar cavity
diffusion of gases through the walls of the alveoli depends on:
- membrane thickness
- diffusion coefficient of a gas
- surface area
- partial pressure differences
(#s 1-3 aren’t a problem in healthy individuals)
membrane thickness
the membranes in alveoli and capillaries are both very thin, which allows for easy diffusion of gases
diffusion coefficients of gases
measure how easily a gas diffuses through a liquid or tissue
- based on how soluble the molecule is and the size of the molecule
- gases with greater diffusion coefficients require less pressure to move from one area to another
surface area
of alveoli and how many capillaries they come in contact with
- this declines as we get older
partial pressure differences
gas moving from an area of higher to lower partial pressure, we want this pressure to equalize
Dalton’s law
- each has in a mixture of gases exerts its own pressure as if all other gases aren’t there
- the total pressure is a sum of all the pressures of the individual gases
atmospheric pressure
760mmHg
because it =PO2 + PCO2 + PN2 + PH2O
partial pressure of O2
20.9%
= 158.6 mmHg
partial pressure of CO2
0.04%
= 0.3mmHg
partial pressure of N2
78.6%
= 597.4mmHg
partial pressure of H2O
0.3%
= 2.3mmHg
- changes the most depending on altitude, location, time of year
explain thinner air at higher altitudes
because pressure gets to be less when molecules are more spread out
- the closer to the surface of the earth you are, the more molecules there are so the pressure is greater
- people going to higher altitudes find it harder to breathe so they take oxygen with them to maintain driving pressure
Henry’s law
the concentration of a gas in a liquid is determined by its partial pressure and its solubility coefficient
ie. [dissolved gas] = partial pressure of the gas X its solubility coefficient
solubility of CO2 compared to O2
N2 compared to O2
- CO2 is 24 times more soluble than O2
- N2 has even lower solubility than O2 because of the high pressure in the atmosphere
deep sea diving and N2
deep sea diving and increased pressure forces more N2 to dissolve into the blood under the increased pressure of the system
- as you come back to the surface, the N2 comes out of solution so it becomes bubbles in blood and tissues and if it doesn’t, it results in decompression sickness
modes of oxygen transport in the blood
- dissolved under pressure (1.5%)
- bound to Hgb on RBC (98.5%)
partial pressures of O2 in the body
- inspired air PO2: 159 mmHG
- alveolar air PO2: 105 mmHg - decreased caused by addition of H2O and loss of O2 to blood (moisture is added to prevent loss of alveolar fluid)
- pulmonary veins PO2: 100 mmHg - decrease again because of equalization of pressures (PO2 in veins is 40 mmHg), also mixing with deoxygenated blood from bronchial veins
modes of carbon dioxide transport in the body
7% dissolved in plasma
23% bound to Hgb on RBC (carbaminohemoglobin)
70% as bicarbonate ions
partial pressures of CO2 in the body
- body tissues PCO2: 45 mmHg
- alveolar air PCO2: 40 mmHg
- atmospheric air PCO2: 0.3 mmHg
- doesn’t change as much as O2 because is more soluble and the atmospheric pressure is lower
oxygen transport on Hgb
4 heme groups on Hb can carry up to 4 oxygen molecules
- when 4 oxygen molecules are bound, the Hb is 100% saturated
- this can be explained by the oxyhemoglobin dissociation curve
oxygen-hemoglobin dissociation curve
describes the % Hb saturated with oxygen at any given PO2
- S shaped curve, affecte by pH, PCO2, temperature and 2, 3-bisphosphrglycerate (BPG)
- when 100% saturated, Hb has a high affinity for oxygen, every time you remove an oxygen, the affinity for it decreases, giving the curve its S-shape
- when the Po2 in cells drops, more oxygen leaves the Hb and at this point they’re at the muscle cells so this is good
the effect of pH on the oxyhemoglobin dissociation curve
increased pH shifts left, decreased pH shifts right
- as acidity increases, oxygen’s affinity for Hgb decreases
this is called the Bohr effect: H+ binds to Hgb and alters its shape, and oxygen is left behind in needy tissues
the effect of CO2 on the oxyhemoglobin dissociation curve
increased CO2 shifts right, decreased CO2 shifts left
- CO2 converts to carbonic acid and becomes H+ and bicarbonate ions and lowers pH
the effect of temperature on the oxyhemoglobin dissociation curve
increase temp shifts right, decrease temp shifts left
- metabolism produces heat as a byproduct and as temperature increases, more oxygen is released
the effect of BPG on the oxyhemoglobin dissociation curve
BPG is released by RBCs as they break down glucose for energy
when BPG binds to Hgb, it increases oxygen release from the Hbg
- happens more when oxygen is low and RBCs produce more BPG
what is BPG
2,3-bisphosphoglycerate
Haldane effect
Hgb that’s released oxygen binds more readily to carbon dioxide than Hgb that already has oxygen bound to it
write out the bicarbonate ion reaction
write it out
chloride shift
when bicarbonate leaves RBC, chloride ions area added into RBC for each one leaving to balance the electrical gradients
how does pulmonary ventilation work
- alternating pressure between atmosphere and the lungs by altering the pressure in the lungs so low or high relative to the atmosphere
- air moves into the lungs when pressure inside is less than atmospheric pressure causing volume of the lungs to increase the volume of the thoracic cavity and causing a pressure drop, drawing air inside
- the opposite happens for when air moves out of the lungs
Boyle’s law
as the size of a closed container decreases, pressure inside increases
- thus, pressure is inversely proportional to volume
- changing the size of the alveoli changes the pressure
alveolar pressure during inspiration
at the end of expiration, atmospheric pressure is equal with alveolar pressure and there’s no air movement then alveolar volume increases and alveolar pressure decreases, causing air to move into the alveoli
alveolar pressure during expiration
at the end of inspiration, atmospheric pressure is equal with alveolar pressure. so when alveolar pressure is greater than atmospheric pressure, air moves out
diaphragm and breathing
contraction (moves downward) and flattens dome shape, increasing the vertical dimension of the chest
- accounts for 65-75% of the volume changes
movements of the ribs during breathing
movement of the ribs (7-10) up and out changes lateral and anterior/posterior dimensions of chest cavity
factors affecting ventilation
surface tension of alveolar fluid
compliance of the lungs
airway resistance
surfactant
a lipoprotein that keeps water molecules from being too attracted to each other and walter can’t form droplets as a result
- is produced by type II pneumocytes
surface tension of alveolar fluid
the thin lauer of alveolar fluid coats the inner surface of alveoli exerting a surface tnesion
- surfactant produced by type II pneumocytes decreases surface tension below the surface tension of water
- during breathing, we must overcome the sirface tension in order to expand the lungs during inhalation
- it also accounts for 2/3 of elastic recoil during exhalation
pleural pressure
pressure in the pleural cavity is always less than atmospheric pressure and intra-alveolar pressure
- during inhalation, the diaphragm contracts and chest wall expands
- parietal pleura moves with the cavity and and increases the volume of the pleural cavity, decreasing the pressure of the inter-pleural cavity
- suction effect of pleural fluid allows parietal fluid to pull the visceral pleura with it which increases the volume of the lungs and drops the internal alveolar pressure allowing inhalation to occur
compliance of the lungs
how much effort is required to stretch the lungs and chest wall
is related to 2 factors:
- surface tension
- elasticity
due to the elastic fibers and surfactant, the lungs are usually highly compliant
infant respiratory distress syndrome
often in prematurely born babies
- don’t produce enough or too much surfactant in alveoli and can make the alveoli collapse
- babies have very laboured breathing and respiratory muscles have to work very hard and often fatigue very easily
- give babies pressurized air with surfactant until their body starts producing its own
airway resistance
bronchioles reduce resistance during inhalation via vasodilation and increase resistance during exhalation by contracting smooth muscle
SNS: releases NE and relaxes smooth muscle in airway causing dilation and reducing resistance
PNS: released ACh, and causes smooth muscle to contract and increases resistance
spirometer
measures air inspired/expired
tidal volume
amount of air inspired/expired withe each breath
500mL at rest
inspiratory reserve volume
amount that can be inspired forcefully after inspiration of tidal volume
3100ml at rest
expiratory reserve volume
amount that can be forcefully expired after expiration of the tidal volume
1200ml at rest
residual volume
volume still remaining in respiratory passages and lungs after most forceful expiration, otherwise lungs would collapse
1200ml
inspiratory capacity
tidal volume plus inspiratory reserve volume
3600ml
functional residual capacity
expiratory reserve volume + residual volume
2400ml
vital capacity
- the sum of inspiratory reserve volume, tidal volume and expiratory reserve volume
or - total lung volume - residual volume
4800ml
total lung capacity
sum of inspiratory reserve volume, expiratory reserve volume, tidal volume, and residual volume
6000ml
minute ventilation
total air moved into and out of the respiratory system each minute
= tidal volume x respiratory rate
respiratory rate (respiratory frequency)
number of breaths taken/minute
- typically 12 times/min = 6L/min
anatomic dead space
conducting zone
formed by nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, and terminal bronchioles
alveolar ventilation
volume of air available for gas exchange/min
