1. Respiratory System
Exercises 36 and 37

2. Respiration
Entire process of exchanging gases between the atmosphere and body cells is called respiration.
Breathing or ventilation – moving air in and out of the lungs
External respiration – exchange of gases between the air in the lungs and the blood.
Internal respiration – exchange of gases between the blood and body cells.
Cellular respiration – use of O2and production of CO2 by cells of the body

3. Organs of the Respiratory System:
Two parts or tracts:
Upper respiratory tract (URT) – nose, nasal cavity, sinuses and pharynx
Lower respiratory tract – larynx, trachea, bronchial tree, and lungs

7. Pharynx Muscular tube lined by mucous membrane Nasopharynx –
Respiration – lined with pseudostratified ciliated columnar epithelium
Oropharynx and Laryngopharynx
digestion and respiration
Nonkeratinized stratified squamous epithelium

8. Larynx Connects pharynx and trachea Passage of air in and out of lungs
Prevents foreign objects entering trachea
Contains vocal cord – speech
Muscle and 9 cartilages connected by elastic tissue

10. Thyroid cartilage “Adam’s Apple”
In female more rounded – shorter front to back – shorter vocal cords
In male more “V” shaped – longer front to back – longer vocal cords

11. Cricoid cartilage – inferior to thyroid cartilage. Marks end of larynx
Epiglottic cartilage – elastic cartilage
Attaches to thyroid cartilage and supports epiglottis
Arytenoid cartilages and
Corniculate cartilages serve as sites for muscles that regulate tension on vocal cords and aid in closing larynx during swallowing
Cuneiform cartilages in mucous membrane – stiffen soft tissue

12. Vocal cords
Two sets of muscle and connective tissue covered by mucous membrane
Upper are “false vocal cords” –close off glottis to keep food out
Lower are true vocal cords – sound produced when air forced across them.
Pitch changed by amount of tension – modified by resonating chambers, and position of lips, mouth and tongue

15. Trachea “windpipe” Extends from larynx to primary bronchi (T5)
Smooth muscle – trachealis muscle
20 – “C” shaped rings of hyaline cartilage
Open end of C posterior to allow esophagus to expand in
Lined with pseudostratifed ciliated columnar epithelium
Ridge – carina – most sensitive areas for triggering cough reflex

21. Bronchial Tree Right and left primary bronchi
Right bronchus shorter, wider, more vertical
Secondary or lobar bronchi
3 branches on right ; 2 on left
Tertiary or segmental bronchi
10 branches on right; 8 on left
Bronchi lined with pseudostratified ciliated columnar epithelium
Held open by complete rings of cartilage

24. Lungs Separated by mediastinum Pleural membranes
Right has 3 lobes and two fissures, shorter
Left has 2 lobes and one fissure, cardiac notch
Apex, base, hilum

27. Pulmonary ventilation
Air moves depending on a pressure gradient
Before inspiration, pressure in lungs = pressure of atmosphere = 760 mm Hg
Inspiration increases the size of the thoracic cavity and ↓ pressure .
Diaphragm is the most important muscle of inspiration.- 75 % of air

32. Diaphragm is innervated by the phrenic nerve.
Decreases pressure 1-3 mm Hg
Moves 500 ml of air
External intercostals also contract – move ribs up and sternum forward
Strenuous breathing – sternocleidomastoid, scalenes, and pectoralis minor

33. Expiration
Passive process – the diaphragm and external intercostals relax. Elastic recoil of stretched elastic fibers and surface tension of the liquid in the lungs decreases the lung volume and increases the pressure, forcing air out of the lungs.
Forced expiration involves contraction of the internal intercostal and abdominal muscles.

35. Lung volumes
Clinically, respiration = one inhalation and one exhalation – respiratory cycle
Adult breathes about 12 X/ min.
Air volumes can be measured with a spirometer.

37. Lung volumes
Tidal volume – air moved by one respiration, about 500 ml.
Inspiratory reserve volume – additional air taken in during maximal inhalation
Expiratory reserve volume – additional air expired during forced exhalation.
Residual volume – amount of air left in alveoli after forced expiration that keeps them inflated.

39. Respiratory capacities
Inspirational capacity – tidal vol. + inspiratory reserve volume
Functional residual – residual volume + expir. res. vol.
Vital capacity - inspir. Res. + tidal vol.+ expir. Res.
Total lung capacity – sum of all volumes

40. Other lung volumes
Anatomic dead space – due to conducting parts of system

41. Regulation of the Respiratory Center
Respirations can be modified by factors from inside and outside the brain.
Chemical influences:
Central chemoreceptors in medulla oblongata
Sensitive to changes in conc. of CO2 and pH
CO2 + H2O ↔ H2CO3 ↔ H+ + HCO3-
carbon + water carbonic hydrogen bicarbonate dioxide acid ion ion

42. Peripheral Chemoreceptors
Carotid bodies and aortic bodies
Stimulated by oxygen concentration decrease
Send impulses to respiratory centers, and breathing increases
Not triggered until O2 is very low (50 mm Hg)