Thorax Lungs

1. Thorax & Lungs

2. Thoracic Cage Bony structure in a conical shape, narrower at the top & wider at the bottom Sternum 12 pairs of ribs – 1-7 attach to sternum; 8,9,10 attach to costal cartilage; 11 & 12 floating 12 thoracic vertebrae Diaphragm – musculotendinous septum that separates the thorax from the abdomen

3. Anterior Landmarks Suprasternal notch Sternum – manibrium, body, xiphoid process Manubriosternal angle – or Angle of Louis. Continues with second rib. Marks where the trachea bifurcates into right & left bronchi; marks the upper border of the heart Costal angle – right & left costal margins meet here. Usually less than 90 degrees

4. Posterior Landmarks Counting ribs & intercostal spaces more difficult on posterior b/c muscle & soft tissue Vertebra prominens – C7, then T1 Spinous processes – count down the knobs on the vertebrae Scapulae end at 7th or 8th rib 12th rib can feel its free tip

5. Reference Lines Anterior chest – midsternal line, midclavicular line

8. Mediastinum – middle section of thoracic cavity containing esophagus, trachea, heart, & great vessels Pleural cavity – on either side of the mediastinum, contains lungs

9. Lung borders Anterior – apex is highest point, 3-4cm above inner 1/3 of clavicles. Base rests on diaphragm at 6th rib midclavicular line Posterior – apex is near C7. Base is at T10

10. Lung lobes Right lung has 3 lobes & is shorter than left b/c of liver placement Left lung has 2 lobes & is narrower than right b/c heart bulges Lobes are separated by fissures Posterior chest is almost all lower lobe. Upper lobes extend down to T3

11. Pleurae Thin, slippery serous membrane that forms an envelope between lungs & chest wall Visceral pleura lines outside the lungs Parietal pleura lines inside the chest wall Inside pleural cavity is pleural fluid that lubricates for smooth movement during respiration. A vacuum with negative pressure that holds the lungs tight against chest wall

12. Trachea & Bronchial Tree Trachea – anterior to esophagus, 10-11 cm long. Begins at cricoid cartilage in neck & bifurcates just below sternal angle into R & L bronchi. Posteriorly, bifurcates at T4-T5. Right bronchus is shorter, wider, & more vertical . Bronchi lined with goblet cells that secrete mucus that traps particles & lined with cilia that sweeps particles up where they can be swallowed. Made up of elastic, connective tissue to expel air from lungs

13. Acinus Functional respiratory unit that consists of bronchioles, alveolar ducts, alveolar sacs, & alveoli Gaseous exchange occurs across the respiratory membrane in the alveoli

14. Mechanics of Respiration 4 major functions Supplying oxygen to the body for energy production Removing carbon dioxide as a waste product of energy reactions Maintaining homeostasis (acid-base balance) of arterial blood Maintaining heat exchange (less important in humans)

15. O2/CO2 exchange maintains pH balance of the blood within its normal range Control of respirations is involuntary, by respiratory center in brain stem (pons & medulla). Normal stimulus to breathe is an increase in carbon dioxide in the blood (hypercapnia)

16. Changing chest size Air comes in – chest size increases Exhale – chest size decreases Vertically – diameter will move up or down AP diameter – increases or decreases with elevation or depression of ribs

17. Inspiration vs. Expiration Inspiration: increasing size of thoracic container creates a slight negative pressure so air rushes in. Diaphragm descends, lengthens vertical diameter, sternum & ribs elevate thus increasing anteroposterior diameter Expiration is passive: diaphragm relaxes, elastic forces in lungs force the air out

18. Subjective Data Cough SOB Chest pain with breathing Hx of respiratory infections Hx smoking Environmental exposure Self-care behaviors – flu shot, TB skin test