Respiratory System Flashcards
Upper respiratory system
Above larynx
Lower respiratory system
Below the larynx (includes larynx)
Conducting portion
Nasal cavity➡️terminal bronchioles
Respiratory portion
Respiratory bronchioles➡️alveoli
Alveoli
Air-filled pockets w/in lung
-where most gas exchange takes place
Type 1 cells
large, thin, flat cells that cover the majority of the alveolar surface and are primarily responsible for gas exchange in the lungs by forming the air-blood barrier
Simple squamous
Type 2 cells
cuboidal epithelial cells primarily responsible for producing and secreting pulmonary surfactant, a substance that prevents the alveoli from collapsing by reducing surface tension; they also act as progenitor cells for repairing damaged alveolar epithelium by differentiating into type 1 alveolar cells when needed
The nose
Air enter respiratory system:
-through the nostrils (external nares)
-into nasal vestibule
Nasal hairs:
-in nasal vestibule
-first particle filtration system
Pharynx
■ A chamber shared by digestive and respiratory systems
■ Extends from internal nares to entrances to larynx and esophagus
Components of respiratory defense system
-goblet cells and mucosa cells:
-produce mucus that bathes exposed surfaces
-cilia
-sweep debris trapped in mucus toward pharynx
-results: moving carpet of mucus (mucus escalator)➡️particles removed
3 cartilages of the larynx
1) thyroid
2) cricoid
3) epiglottis
Thyroid cartilage
■ with laryngeal prominence (Adam’s apple)
■ Is a hyaline cartilage
■ Forms anterior and lateral walls of larynx
■ Ligaments attach to hyoid bone, epiglottis, and laryngeal cartilages
-Protects vocal cords
-help create sound
Cricoid cartilage
■ Is a hyaline cartilage
■ Form posterior portion of larynx
■ Ligaments attach to first tracheal cartilage
■ Articulates with arytenoid cartilages
maintain the patency of the airway by providing a stable structure within the larynx, serving as an attachment point for muscles that control the opening and closing of the vocal cords
Epiglottis
■ Composed of elastic cartilage
■ Ligaments attach to thyroid cartilage and hyoid bone
■ covered in taste bud-containing mucosa
Trachea
■ Also called the windpipe
■ Extends from the cricoid cartilage into mediastinum
■ where it branches into right and left pulmonary bronchi
Primary bronchi
■ Right and left primary bronchi:
■ separated by an (the carina)
Branching bronchial tree
Trachea➡️ primary brochi➡️ secondary bronchi ➡️ tertiary bronchi ➡️ bronchioles ➡️terminal bronchioles
Primary bronchi goes to
Lungs
Secondary bronchioles goes to
Lobes
3 parts of respiratory membrane
- Squamous epithelial lining of alveolus (Type 1 cells)
- Endothelial cells lining an adjacent capillary
- Fused basal laminae between alveolar and endothelial cells
Pulmonary ventilation
-physical movement of air in and out of respiratory tract
-provided alveolar ventilation
-boyles law: ⬆️volume of cavity➡️⬇️pressure➡️pulls air in from high pressure to low pressure
-contraction and ⬇️volume (size) of cavity➡️⬆️pressure➡️pushes air to area of lower pressure
Boyles law
In contained gas
-external pressure forces molecules closer together
-movement of gas molecules exerts pressure on container
Intrapulmonary pressure
■ Also called intra-alveolar pressure
■ Is relative to Patm
■ In relaxed breathing, the difference between Patm and intrapulmonary pressure is small:
■ about —1 mm Hg on inhalation or +1 mm Hg on expiration
Maximum intrapulmonary pressure
■ Maximum straining by exhaling forcibly , a dangerous activity, can increase significantly:
■ from —30 mm Hg to +100 mm Hg
■ Straining by exhaling forcibly against a closed glottis (aka the Valsalva maneuver) - exhale while lifting)
Intrapleural pressure
■ Pressure in space between parietal and visceral pleura (pleural cavity)
■ Averages —4 mm Hg
■ Maximum of —18 mm Hg
■ Remains below Patm (subatmospheric) throughout respiratory cycle
■ Fluid level must be minimal
■ Pumped out by lymphatics
■ If accumulates: positive Pip pressure ➡️ lung collapse
■ Lungs are held open (expanded) in the pleural cavity by the pleural fluid layer.
■ The elastic fibers in the lungs expand and create the negative pressure
Respiratory muscles during inspiration
Diaphragm- contracts, it moves down and increases the volume of the thoracic cavity, which draws air into the lungs
External intercostals- help move the ribcage up and out, which increases the volume of the thoracic cavity
Respiratory muscles during expiration
- Internal intercostal and transversus thoracis muscles:
o depress the ribs - Abdominal muscles:
■ compress the abdomen
■ force diaphragm upward
Henry’s law
■ When gas under pressure comes in contact with liquid:
■ gas dissolves in liquid until equilibrium is reached
■ At a given temperature:
■ amount of a gas in solution is proportional to partial pressure of that gas
■ Increasing gas pressure increases the amount gas that can go into solution
Pressure in air ⬆️➡️goes to water
O2Hb saturation curve
Saturation of Hb vs partial pressure of O2
-higher Po2➡️⬆️Hb saturation
PO2
pressure exerted by oxygen gas alone within a mixture of gases
pH effect on O2 Hb saturation curve
decrease in pH (more acidic) shifts the oxygen-hemoglobin saturation curve to the right, meaning hemoglobin has a lower affinity for oxygen and releases more oxygen to the tissues, while an increase in pH (more alkaline) shifts the curve to the left, increasing hemoglobin’s affinity for oxygen and making it hold onto oxygen more readily
⬇️pH➡️⬆️O2 release➡️⬇️PO2 and ⬇️Hb saturation
Temp effect on O2Hb saturation curve
An increase in temperature causes the oxygen-hemoglobin saturation curve to shift to the right, indicating that hemoglobin has a decreased affinity for oxygen, meaning it releases oxygen more readily at higher temperatures; conversely, a decrease in temperature shifts the curve left, increasing hemoglobin’s affinity for oxygen and causing it to hold onto oxygen more tightly
When temp ⬆️➡️⬆️O2 release➡️⬇️PO2 and ⬇️Hb saturation
Bohr effect
■ Is the effect of pH on hemoglobin saturation curve
■ When pH goes down, H+ ions bind to Hb and change its shape decreasing its affinity for O2 and vise versa
■ CO2 is not very soluble in blood
■ The change in pH is Caused by CO2:
■ CO2 diffuses into RBC
■ an enzyme, called carbonic anhydrase, catalyzes reaction with H2O
■ produces carbonic acid (H2CO3)
■ H2CO3 is very a soluble ionic compound
■ Carbonic acid (H2CO3):
■ dissociates into hydrogen ion (H+) and bicarbonate ion (HCO3—)
■ Hydrogen ions can diffuse out of RBC, lowering pH
■ Most H+ is removed by buffers, especially
CO2 in the blood stream
-may be:
-converted to H2CO3
-70% transported as H2CO3
-bound to protein portion of Hb
-HCO3- goes into bloodstream
-23% is bound to amino groups of globular proteins in Hb molecule:
-forming carbaminohemoglobin
-H+ gets buffered by Hb
-dissolved in plasma
- 7% is transported as CO2 dissolved in plasma
Respiratory centers of the brain
-both voluntary and involuntary
-main generator: medulla oblongata
-some in the pons
Medullary respiratory centers
Inspiration neurons excite inspiratory muscles via phrenic (diaphragm) and intercostal nerves (external intercostals)
Expiratory neurons ➖ inspiratory neuron
sensory modifiers of respiratory center activities
1) chemoreceptors are sensitive to:
-PCO2, PO2, or pH
-of blood or cerebrospinal fluid
2)baroreceptors of aortic or carotic sinuses
-sensitive to changes in BP
3)stretch receptors
-respond to changes in lung volume
4) irritating physical or chemical stimuli:
-in nasal cavity, larynx, or bronchial tree
Chemical factors
■ Influence of Pco2 (normally most potent; normally most closely controlled)
■ If blood Pco2 levels rise (hypercapnia), CO2 accumulates in brain ➡️pH drops in brain
■ H+ stimulates central chemoreceptors of brain stem
■ Chemoreceptors synapse with respiratory regulatory centers à increased depth and rate of breathing à lower blood Pco2 à pH rises
Baroreceptor reflex
■ Carotid and aortic baroreceptor stimulation:
■ affects blood pressure and respiratory centers
■ When blood pressure decreases :
■ respiration increases
■ When blood pressure increases:
■ respiration decreases
Hypercapnia
⬆️PCO2(⬇️pH) (arterial)in CSF➡️ ➕chemoreceptors in medulla oblongata➡️ ⬆️ respiratory rate➡️⬆️elimination of CO2 in alveoli➡️⬇️ arterial PCO2➡️ hometostasis
Hypoventilation
A common cause of hypercapnia
■ Abnormally low respiration rate:
■ allows CO2 build-up in arterial CSF at alveoli
Hyperventilation
■ Excessive ventilation
■ Results in abnormally low PCO2 (hypocapnia)- ⬆️pH
■ Stimulates chemoreceptors to decrease respiratory rate
