Gross Anatomy

Question 1

pleura

Answer 1

continuous, thin, serous membrane

• parietal pleura: covers the boundaries of the thoracic cavity
• visceral pleura: covers the lungs

Question 2

what is pleural fluid and what is its function?

Answer 2

interstitial fluid derived from capiallaries of parietal pleura; facilitates movement of lungs, increases surface tension to maintain close association between lungs and thoacic wall

Question 3

discrbe the discrepancies between borders of lungs and pleural cavity

Answer 3

lungs never take up the entire pleural cavity, 2 rib discrepancy between inferior borders of lungs and inferior extent of pleural cavity​

• midclavicular line: lung tissue stops at 6th rib but pleura extends to 8th rib
• costal pleura entends to 12th rib, inferior border of lungs at 10th rib

Question 4

pleurisy

Answer 4

inflammation of parietal pleura leads to sharp localized pain over specific regions of the thoracoabdominal wall

• if diaphragm involved, referred over shoulder

Question 5

how is the parietal pleura innervated?

Answer 5

• by branches of sensory fibers contained within intercostal nerves
• diaphragmatic pleura recieves sensory fibers from phrenic nerve (C3-C5)

Question 6

list the parts of the conducting zone of the respiratory system

Answer 6

anatomic dead space solely for passage of air; ciliated surface propels mucous secreted by goblet cells towards the mouth

• trachea
• bronchi (first 16 branches)
  
  • principal
  • secondary
  • tertiary/segmental: smallest airways that have no alveoli/no gas exchange

Question 7

list the parts of the respiratory zone of the respiratory system

Answer 7

specialized for gas exchange

• respiratory bronchiole (last 7 branches of bronchi)
  
  • alveoli: 300 million​
    
    • ducts: elongated cylindar leading to grape-like clusters of alveolar sacs

Question 8

alveoli

Answer 8

basic function units of gas exchange; vast amount of surface area available for gaseous exchange

Question 9

type I alveolar epithelial cells

Answer 9

line alveoli and function for gas exchange

Question 10

type II alveolar epithelial cells

Answer 10

produces surfactant (lipo-rotein containing DPPC) which reduces surface tension at the blood-air interface making it easier to inhale and increasing the mechanical staility of the lung

Question 11

describe the course of the pulmonary arteries

Answer 11

pulmoary arteries→lobar branches→lobar arteries→segmental branches that enter bronchopulmonary segments→divide multiple times at level of terminal ventilator units→half of capillary plexus associated with each alveolus

Question 12

intersegmental pulmonary veins

Answer 12

union of capillaries on venule and arterial sides of pulmonary circuit; run in the connective tissue septa between bronchopulmonary segments

Question 13

what is the danger of englarged lymph nodes in the thoracic cavity?

Answer 13

can get enlarged and push on trachea or disrupt anatomy of principle bronchi, occluding section of airway causing dyspnea

• not well innervated (can be clinically silent)

Question 14

which bronchi is more prone to choking?

Answer 14

R principal bronchi: wider, shorter, and more vertical than the L so objects have a tendancy to be inhaled into it

Question 15

describe the innervation of the pulmonary plexus

Answer 15

• **parasymp from CN X: **smooth muscule of airways (bronchoconstrictor), initiates gladular secretion
• **symp: **smooth muscle of blood vessel walls (vasomotor), monitoy parasymp control of airways (bronchodilators)
• CN X afferent (monitoring)
  
  • ​cough reflex, respond to stretch, prevent overexpansion of lungs (limiting inspiration), pressoreceptors (BP) chemoreceptors (monitor blood-gas levels)
• **afferent (pain): **via intercostal and phrenic nerves; limited afferent fibers accompanry sympathetics, pain detected by fibers and referred over the anterior chest wall (dematomes T1-T5)