Mechanics of Ventilation

Question 1

each bronchopulmonary segment is served by…. (3 things)

Answer 1

1. segmental/tertiary bronchus
2. pulmonary artery
3. pulmonary vein

*note branches of pulmonary arteries run alongside the bronchi

Question 2

carina is at what vertebral level?

Answer 2

carina = bifurcation of trachea, T4-T5, aka sternal angle

right main bronchus more vertical and large in diameter

Question 3

what causes a tracheoesophageal fistula?

Answer 3

tracheoesophageal fistula: esophagus separated into 2 parts, one or both parts coming off the trachea (and not connected with each other)

failure of tracheoesophageal ridge - separates trachea and esophagus during development (grown from foregut)

most common form: upper esophagus ends in blind pouch, distal esophagus forming fistula with trachea

Question 4

the head of the ribs articulates with ______

the tubercle of the ribs articulate with _____

Answer 4

the head of the ribs articulates with 2 vertebral bodies

the tubercle of the ribs articulate with transverse process

Question 5

contrast function of external vs internal intercostal muscles during breathing

Answer 5

E is I and I is E

External intercostal for Inspiration

Internal intercostal for Expiration

Question 6

what are the 5 muscles involved in respiration?

Answer 6

1. diaphragm
2. scalenes
3. sternocleidomastoid
4. external intercostals
5. internal intercostals

Question 7

what happens during inspiration to allow air to enter the lungs?

Answer 7

force of muscular contraction (diaphragm) exceeds elastic recoil and thoracic cavity enlarges

intrapleural pressure becomes even more negative

alveolar pressure drops below atmospheric pressure and air enters

Question 8

what happens when there is unilateral loss of the phrenic nerve?

Answer 8

paradoxical movement of diaphragm (paralysis of hemidiaphragm)

Question 9

how does forced exhalation (including laughing, coughing) affect volumes in the heart?

Answer 9

expiration raises intrathoracic pressure —> impeded venous return to the heart

Question 10

through which nerve does the cough/sneeze reflex work?

Answer 10

vagus nerve —> airway receptors —> respiratory epithelium

afferent fibers also follow bronchial tree back to CNS via vagus nerve - provide feedback about stretch/pressure in pulmonary veins

Question 11

sympathetic and parasympathetic fibers in the lungs are pre/postganglionic, respectively?

Answer 11

parasympathetic - preganglionic

sympathetic - postganglionic

Question 12

describe open pneumothorax

Answer 12

open (sucking) pneumothorax: air enters pleural cavity and lung collapses because negative intrapleural pressure is lost

on inspiration, atmospheric pressure on injured side causes mediastinum shift to intact side, compressing the lung there

patient is cyanotic and in severe respiratory distress or shock, immediate closure of wound imperative

Question 13

describe tension pneumothorax

Answer 13

tension (positive pressure) pneumothorax: flap of penetrated tissue acts as a one-way valve which opens on inspiration and closes on expiration

inspiration: ipsilateral lung collapses and mediastinum shifts to contralateral side, causing compression

expiration: valve is closed and air is trapped, pressure increases with each breath

Question 14

hemothorax

Answer 14

blood fills intrapleural space, compresses lung