Lesson 1 Flashcards
Three parts of sternum:
manubrium, body, xiphoid
Angle of Louis
sternal angle
level of bifurcation of trachea
Provides pump-handle action of sternal body during inspiration
True ribs
ribs 1 to 7 (vertebrosternal ribs)
False ribs:
Ribs 11 to 12 (vertebral) – only vertebral attachment, “floating ribs”
Muscles of Inspiration:
Diaphragm + External Intercostal Ms + Accessory Ms
Muscles of Expiration:
Abdominal Ms + Internal Intercostal Ms (forceful expiration)
Accessory muscles of ventilation:
sternocleidomastoid, scalene, upper trapezius, pectoralis major/minor, serratus anterior, rhomboids, latissimus dorsi, serratus posterior superior, thoracic erector spinae
Upper Respiratory Tract
Nose
Pharynx – naso, oro, laryngo
Larynx
Lower Respiratory Tract
Tracheobronchial Tree – conducting airways Trachea Main stem/lobar bronchi Segmental/subsegmental bronchi Terminal respiratory (Acinar) units
Hilius
point at which the nerves, vessels, and primary bronchi penetrate the parenchyma
Conducting airways or Conducting Zone or Tracheobronchial Tree
Trachea
Main stem/lobar bronchi
Segmental/subsegmental bronchi
Acinar/terminal respiratory units or Respiratory Zone
Respiratory bronicoles
Alveolar ducts
Alveoli – the functional unit
Parasympathetic control of lungs:
bronchial constriction, dilation of pulmonary smooth ms
Sympathetic control of lungs:
bronchial dilation and slight vasoconstriction
Tidal volume
350-500 mL
volume of air normally inhaled and exhaled with each breath during quiet breathing
Minute ventilation
ventilatory rate × tidal volume
Inspiratory reserve volume (IRV):
additional volume of air that can be taken into the lungs beyond normal tidal inhalation
(3000mL)
Expiratory Reserve Volume (ERV):
additional volume of air that can be let out beyond normal tidal exhalation (1100mL)
Residual Volume (RV):
volume of air that remains in the lungs after a forceful expiratory effort
(1200mL)
Inspiratory Capacity (IC):
sum of the tidal volume and inspiratory reserve volumes
maximum amount of air that can be inhaled after normal tidal exhalation
(3500mL)
Functional Residual Capacity (FRC):
sum of the expiratory reserve and residual volume
Amount of air remaining in the lungs at the end of normal tidal exhalation
(2300mL)
What does functional residual capacity represent?
the point at which the forces tending to collapse lungs are balanced against the forces tending to expand chest wall
Vital Capacity (VC):
sum of the inspiratory reserve, tidal, and expiratory reserve volumes
Maximum amount of air that can be exhaled following a maximum inhalation
(4600mL)
Total Lung Capacity (TLC):
maximum volume to which lungs can be expanded
Sum of all the pulmonary volumes
(5800 mL)
Chemoreceptors
sense alterations in blood pH, carbon dioxide, and oxygen levels
What affects breathing?
lung compliance, elasticity, surface tension
Boyle’s law
pressure of given quantity of gas is inversely proportional to its volume
Inspiration
negative intrapulmonary pressure (volume increases)
Expiration
intrapulmonary pressure exceeds atmospheric pressure (volume decreases)
Mechanical Ventilation:
lack ability to generate an effective negative pressure or subatmospheric pressure
Transmural pressure
difference between intrapulmonary and intrapleural pressures and maintains lung near chest wall
Paradoxical breathing:
changes in lung volume do not parallel normal inward and outward pull during inspiration and expiration, they are OPPOSITE
Often seen in patients with multiple rib fractures and flail chest
Physical properties of lungs
compliance
elasticity
surface tension
resistance to airflow
Compliance
tendency to collapse or recoil while inflated
Elasticity
tendency of structure to return to its initial size after being distended
What affects resistance to airflow?
pressure differences, diameter and length of airway
Ventilation and Perfusion Matching
Optimal respiration or gas exchange occurs if distribution of gas (ventilation) and blood (perfusion) match at level of alveolar capillary interface
Systole
period of ventricular contraction
Diastole
period of ventricular relaxation
Cardiac Output
Heart Rate × Stroke Volume
4-6L/min at rest on average
Sympathetic effect on HR
increase heart rate via SA node
Parasympathetic effect on HR:
slows heart rate via SA node
Pre-load
blood returning to heart or end diastolic volume (EDV)
Frank-Starling mechanism:
greater volume of blood is ejected out of the ventricles when greater volume of blood is returned to the heart
Afterload
blood ejected out of heart is influenced by pressure generated in ventricle compared to pressure in systemic vasculature
Who is preload increased in?
hypervolemia
regurgitation of cardiac valves
heart failure
Who is afterload increased in?
hypertension
vasoconstriction
Ejection Fraction
Ratio of volume of blood ejected out of ventricles relative to volume of blood received by ventricles
Normal = 60% to 70%
end-systolic volume (ESV)
Blood remaining in ventricles following contraction
Venous Return
return of blood to the right side of the heart
What affects venous return?
total blood volume and pressure within the venous vasculature
