Exercise 23: Anatomy of the Respiratory System Objectives: Functional Anatomy of the Respiratory System Name the organs forming the respiratory passageway from the nasal cavity to the alveoli of the lungs (or identify them on a diagram or model) and describe the function of each. Describe several protective mechanisms of the respiratory system. Describe the structure and function of the lungs and the pleural coverings.

Upper Respiratory Tract Structures Figure 13.2

Trachea (Windpipe) Walls are reinforced with C-shaped hyaline cartilage The cartilaginous reinforcements keep the trachea open during the pressure changes that occur during breathing. The incomplete rings of the posterior tracheal surface make it flexible, allowing a food bolus traveling through the posterior esophagus to bulge anteriorly. Figure 13.3b

Structures of the Larynx “lid” for larynx= epiglottis Adam’s apple = thyroid cartilage broader anteriorly= cricoid cartilage

13 12 11 10 7 primary bronchus 8 secondary bronchus 2 Nasal cavity 3 Nasopharynx 1 External Nares 4 Oropharynx 5 laryngopharynx 6 Trachea 13 7 primary bronchus 12 8 secondary bronchus 11 9 tertiary bronchus 10

Pleural Membranes Pleural membranes produce lubricating serous fluid that fills the area between layers of pleura. The pleural fluid lubricates the pleural surfaces and allows the layers of pleura to slide against each other easily during respiration. The outer pleura is attached to the chest wall. The pleural fluid between the two layers provides the surface tension that keeps the lung surface in contact with the chest wall. 33

Functions of the Nasal Cavity Mucosa The mucosa contains blood vessels, nerves, and small glands (these glands secrete fluids into the nasal cavity). The mucosa supports small hair-like projections called cilia. These cilia carry the mucous blanket from the front of your nose to the back, and from the sinuses out into the nose, and then into the back of your nose from whence the mucous is swallowed. Nasal cavity mucosa warm, moisten, and filter the incoming air,

Primary Bronchi Right bronchus: Left bronchus: shorter longer more horizontal larger diameter easier for foreign object to be lodged here Left bronchus: longer more vertical smaller diameter

Phrenic Nerve: nerve that activates the diaphragm during inspiration

Palate: “floor” of the nasal cavity

Esophagus: food and fluid passageway inferior to the laryngopharynx

Epiglottis: flaps over the glottis during swallowing of food

Vocal cords are located in the larynx

Organs of the Respiratory System Nose Pharynx Larynx Trachea Bronchi Lungs—alveoli Figure 13.1

Pleural Layers Parietal pleura- Viseral pleura- Pleural layer lining walls of thorax; (attached to chest wall) Viseral pleura- Pleural layer covering lung

Alveolus

Uvula: The small piece of soft tissue that can be seen dangling down from the soft palate over the back of the tongue. The uvula is described variously shaped like a U, a tear or a grape. Its name comes from the Latin word for "grape," uva. The uvula has its own little muscle, the musculus uvuae, to help it stiffen and change shape, so it helps fill in the space at the back of the throat. It helps keep food from going down the wrong way down the breathing passage when one swallows. Singers credit the uvula with letting them produce a vibrato, a wavy up-and-down sound. The uvula is one of the soft-tissue structures commonly blamed for snoring and for sleep apnea (a break in breathing during sleep). Some treatments for these conditions involve removing excess flesh from the uvula and surrounding areas. The surgery, called uvulopalatopharyngoplasty, is designed to tighten up flabby tissues and enlarge the upper air passages.

Glottis- opening between the vocal cords

Conchae- increase air turbulence in the nasal cavity As air passes over the turbinate tissues it is heated to 32° C to 34° C, humidified (up to 98% water saturation) and filtered

External Respiration External respiration—gas exchange between pulmonary blood and alveoli Oxygen is loaded into the blood Carbon dioxide is unloaded from the blood

Internal Respiration- exchange of gases between the body cells and blood. Exchange of gases to and from blood capillaries of the systemic circulation

Lung Inflation in Sheep Pluck http://www.youtube.com/watch?v=zlH0o9MZVmI&NR=1 Watch how the lung inflates part by part. When the pressure is released the lung deflates due to presence of elastic tissue

Tracheal Epitheleum Cilia- to push mucus and dust off lungs Goblet cells – produce mucus

Pseudostratified Epithelium Tissue All of the cells of pseudostratified epithelium rest on a basement membrane; however, some of its cells are shorter than others, and their nuclei appear at different heights. As a result, the epithelium gives a false impression that its stratified.

Alveoli & Capillaries

Simple Diffusion of Oxygen into Capillary Blood Due to simple diffusion, oxygen diffuses from the alveoli into blood because concentrations of O2 is higher in the alveoli.

Simple Diffusion of Oxygen and Carbon Dioxide at Body Tissues Oxygen leaves blood- enters cell Carbon Dioxide leaves cell- enters blood