3.C Lungs Flashcards
Function on respiratory system
Supple oxygen, remove CO2, regulat pH, smell, filter air, produce vocal sounds, excrete water and heat (small amounts of water and heat)
4 basic processes involved in respiration
Pulmonary ventilation (breathing) External respiration (alveolar gas exchange) Internal resp (tissue resp) Cell resp
Pulmonary ventilation
Exchange of oxygen and carbon dioxide between atmosphere and lungs
External respiration
Exchange of oxygen and CO2 between lungs (alveoli) and blood (pulmonary caps)
Internal respiration
Exchange of oxygen and CO2 from blood to tissue
through interstitium
Cellular respiration
Within cells, oxygen utilized
Two divisions of respiratory system
Structural and function
Division of upper and lower airway structurally
Pharynx and superior is upper, larynx and inferior is lower
Functional division of respiratory system
Conducting zones are all the way to terminal bronchioles and superior
Respiratory zone includes respiratory bronchioles, alveolar ducts/sacs and alveioli
Functions of the nose
Conduct air Moisten and warm air Filter air (hair, cilia, mucosa) Smell Speech (resonating chamber)
Paranasal sinuses
Located in cranial and facial bones near the nasal cavity.
They are air filled cavities lined with mucosa, goblet cells, and cilia
Functions of the paranasal sinuses
Reduce weight of the skull, resonance chambers for speech, warm and moisten air
Pharynx
13 cm, from internal nares to level of cricoid cartilage.
Passageway for air and food, resonating chamber for speech
3 regions of pharynx from superior to inferior
Naso, oro, and laryngopharynx
Nasopharynx
Posterior to nasal cavity, to soft palate.
Two internal nares, two openings for eustachian tubes, opening into oropharynx.
Lined with pseudostratified ciliated columnar epithelium, and cilia to move mucus down toward inferior portion of pharynx.
Nasopharynx exchanges small amounts of air within auditory (through eustachian tubes) to balance inner ear pressure
Soft palate (nasopharynx)
Posterior portion of the roof of the mouth, arch-shaped muscular partition between naso and oropharynx.
Oropharynx
Posterior to oral cavity, from soft palate to level of hyoid bone. Only opening is fauces (throat)
(opening into mouth)
Passageway for air, food and drink.
Because of food abrasion its lined with nonkeratinized stratified squamous epithelium.
Two pairs of tonsils found in oropharynx
Palatine and lingual
Tonsil in nasopharynx
Pharyngeal or adenoid
Laryngopharynx
Hypopharynx. From hyoid bone to esophagus. Also has nonkeratinized stratified squamous epithelium.
For food drink and air
Tonsillectomy removes
palantine and lingual
Lower respiratory
Larynx, trachea, bronchi, lungs
Larynx
Produces voice sounds, contains 9 pieces of cartilage, vocal cords and folds of mucosa
Is the voice box.
C4-C6
Cavity of larynx is space between entrance of larynx to inferior border of cricoid cartilage
Cartilage of larynx
Thyroid, epiglottis, cricoid cartilage and three pairs arytenoid, cuneiform, and corniculate.
Arytenoid cartilages
Influence changes in position and tension of vocal folds (true vocal cords)
Thyroid cartilage
Two fused plates of hyaline cartilage, present in males and females. Test makes it bigger
Thyroid cartilage is connected to hyoid bones by thyrohyoid membrane
Laryngeal vestibule, infraglottic cavity
Areas above and below vestibular folds (false vocal cords)
Epiglottis
Large, leaf shaped, elastic cartilage covered in epithelium. Stem is tapered inferior portion attaching to thyroid cartilage, leaf is broad unattached freely moving (up and down) portion.
Swallowing pharynx larynx
They rise, elevation of pharynx widens it to receive food or drink.
Elevation of larynx causes epiglottis to move own and form a lid over glottis
Glottis
Consists of a pair of folds of mucous membrane, vocal folds (true cords) and space between (rima glottidis)
Trachea
12cm long 2.5 diameter
Anterior to esophagus, extends from larynx to superior border of T5, where it divides into R and L bronchi
Branching of bronchial tree
Trachea to primary bronchi to secondary to tertiary to bronchioles to terminal bronchioles
Bronchi
At T5 trachea divides to R and L main bronchi.
R is shorter, wider, more vertical (food goes in here)
Carina
Where trachea divides into R and L main bronchi. It is an internal ridge formed by a posterior and somewhat inferior projection of the last tracheal cartilage.
Cough reflex is sensitive here.
Widening and distortion of carina is a sign of carcinoma of lymph nodes
Main bronchi divide into
Lobar (secondary) bronchi (one for each lobe) which continue to branch to segmental (tertiary) bronchi that supply specific bronchopulmonary segments
Segments divide into bronchioles which branch repeatedly into terminal bronchioles.
Segments
Ten in right, 9 in left.
Each has its own bronchopulmonary branch and vasculature
A segment can be surgically removed without seriously disrupting surrounding tissue
Parietal and visceral pleura
Enclose and protect lung, line pleural cavity and secrete pleural fluid to reduce friction
Microscopic airway branching
Respiratory bronchioles to alveolar ducts to alveolar sacs to alveioli
Type I alveoli
Squamous cell epithelium. More numerous, and are the site of gas exchange
Type II alveoli
Found between type I. Cuboidal epithelial cells with free surfaces containing microvilli to secrete alveolar fluid, which keeps the surface and air moist.
This fluid also contains surfactant (phospholipids and lipoproteins) to lower surface tension and prevents alveoli collapse
Alveolar macrophages
Remove fine dust particles and other debris from alveolar spaces.
Physics of gases
Air moves from high to low pressure, therefore atmospheric pressure needs to be greater than in the lungs to move air in
Boyle’s law
The pressure of a gas in an enclosed container is inversely proportional to the volume of the container
At rest diaphragm relaxed pressures
Atmospheric 760
Alveolar 760
Intrapleural 756
During inhalation pressures
Alveolar 758
Intrapleural 754
Diaphragm contracts and flattens
Exhalation pressures
Alveolar 762
Intrapleural 756
Diaphragm relaxes
Tidal Volume
Volume of one breath
Average 500mL
Minute volume
Tidal volume X resps over 1 minute.
12X500mL = 6L
Tidal volume facts
70% (350mL) hits respiratory zone (resp bronchioles and beyond)
30% conducting zone, nose to terminal bronchioles (anatomic dead space)
Anatomic dead space rule of thumb
Its about the same as ideal body weight in pounds
Alveolar ventilation rate
Volume or air per minute that actually reaches respiratory zone (bronchioles on)
Inspiratory reserve
Amount can that be taken after normal tidal volume
3100mL males
1900mL females
Expiratory reserve
Amount that can be forced out after tidal volume
1200mL males
700mL females
(residual after this is 1200males 1100 females)
Inspiratory capacity
Tidal volume + inspiratory reserve
Functional residual
Expiratory reserve plus residual
Vital capacity
Everything minus residual
6000-1200 males
4200-1100 in females
Dalton’s law
Each gas in a mixture of gasses exerts its own pressure as if no other gasses were present
The sum of the pressure of the gases = atmospheric pressure
E.G Pn2 (pressure of nitrogen gas) is 78.6 % of 760mmHg or .786 X 760 = 597.4mmHg
Henry’s law
Quantity of gas that will dissolve is proportional to partial pressure and solubility
Very little nitrogen dissolves in blood as its solubility is so low
CO2 24X greater
Higher pressure causes more dissolving (pop under pressure keeps CO2 dissolved)
Nitrogen can get into blood undersea because of higher pressures, slow ascent allows exhalation of gas
Boyles law
Pressure of gas inversely proportional to volume
Allows movement of gases as lung size changes
Forced inspiration
Requires energy for accessory muscle use
Muscles of inhalation
Sternocleidomastoid
Scalenes
External intercostals
Diaphragm
Muscles of exhalation
Internal intercostals
External oblique, internal oblique, rectus abdominis, transverse abdominis
Partial pressures of CO2 and O2
Atmospheric CO2 0.3 O2 159
Arterial CO2 40 O2 100
Deoxygenated CO2 45, O2 40
External resp
Simple diffusion through thin alveolar membrane
Large total surface are (70m squared)
RBCs pass single file through pulmonary capillaries
How O2 is carried
1.5 dissolved 98.5 on hemoglobin (4 each) bound to RBCs
The globins
Oxyhemoglobin
Deoxyhemoglobin (with or without O2)
Factors that affect binding
O2 partial pressure (increases binding) pH PCO2 Temp Presence of 2,3 biphosphoglycerate
Acidity binding
Low pH shifts curve to right
Right shift means
O2 saturation percentage will be lower (less) at same O2 pressure (lower affinity) (more likely to diffuse off)
PCO2 binding
High PCO2 shifts to right
Temperature binding
High temp shifts curve to R
2,3 BPG binding
BPG released during glycolysis in RBCs, decreases affinity (right shift)
CO2 in blood
7% in plasma
23% carbaminohemoglobin
70% bicarb (HCO3-)
CO2 + H20 H2CO3 H + HCO3-
Chloride shift
As HCO3- accumulates inside RBCs, some diffuses into plasma and Cl- diffuse in
End result is CO2 carried from tissue cells as HCO3- in plasma
Influences on rate and depth of breathing
Cerebral cortex for voluntary control
Chemical regulation from chemoreceptors
Movement (propiceptors)
Baroreceptors (bronchi, lungs)
Overactivation of stretch receptors
Impulse to pneumotaxic center which sends impulses to inspiratory and apneustic areas to inhibit inspiration
More influences on rate and depth of breathing
BP (carotid and aortic bodies baro receptors) Limbic system - emotions Temperature Pain Stretching of the B hole Irritation of airways
