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Module 05 Lab Worksheet: Respiratory System

Introduction
This week’s lab will focus on understanding the anatomy and physiology of the respiratory system along with the mechanics of breathing.

Objectives
Objectives for this week’s lab include: 1) Identify the anatomy of the respiratory system, 2) Describe the physiological mechanism of breathing and the anatomical structures involved and 3) Identify the anatomical structures of the respiratory system on a pig specimen.

Overview
The respiratory system’s main function is to provide the body with oxygen and dispose the carbon dioxide that is created from the body’s cells. Remember the importance of oxygen and the reason why cells create carbon dioxide? Cellular respiration and ATP production ring a bell? In general, Oxygen + Glucose = ATP + Carbon dioxide + Water. The respiratory system needs to supply the body with oxygen to produce ATP (our body’s energy source) and dispose the gaseous carbon dioxide waste. Any dysfunction to the respiratory system could create systemic problems with the lack of oxygen being supplied to the body.

The respiratory system is divided into the upper and lower respiratory system. The upper respiratory system consists of the: Nasal cavity, nasopharynx, oropharynx, laryngopharynx, and larynx. The upper respiratory system assists in humidifying, filtering and providing a pathway of air to the lower respiratory tract. The trachea, bronchi, bronchial tree, alveolar sacs, and the alveoli compose the lower respiratory system. The alveoli and alveolar sacs are the location where the gas exchange occurs- oxygen diffuses from the alveoli to the blood, specifically the hemoglobin of the red blood cells and carbon dioxide diffuses from the red blood cells and plasma to the alveoli to be expelled from the body.

Pulmonary ventilation, more commonly known as the breathing process, consists of two phases: Inspiration- when air flows into the lungs and Expiration- when air is expelled from the lungs. The process of pulmonary ventilation is dependent upon the respiratory muscles, the elasticity of the lung tissue, the parietal and visceral pleura, along with the atmospheric and intrapulmonary pressure. It is important to understand that as a volume of a space increases, the pressure decreases and as a volume of space decreases, the pressure increases. Air will move from an area of high pressure to low pressure- like diffusion, movement of molecules from an area of high concentration to low concentration.

Lung tissue is elastic meaning it can increase in size but will recoil back to its original shape and size- like a rubber band. As the respiratory muscles contact, they pull on the parietal and visceral pleura, which cause the lung tissue to stretch ultimately increasing the volume within the lungs. The increased volume within the lungs causes the intrapulmonary pressure to decrease and when the intrapulmonary pressure falls below atmospheric air pressure, air will flow into the lungs. When the respiratory muscles stop contracting, there is no longer any pull on the lung tissue and due to elastic properties of the lung tissue, it recoils back to its original size. This decreases the volume within the lungs ultimately increasing the intrapulmonary pressure above atmospheric air pressure causing air to be “pushed” out of the lungs.

The pulmonary ventilation process obviously depends on inspiration and expiration and various respiratory capacities can be measured to evaluate a person’s respiratory status. There are a number of respiratory volumes, such as tidal volume and expiratory reserve volume that can be measured by a device called a spirometer.

Materials
2-liter plastic bottle
Rubber bands, balloons, straws and modeling clay
Spirometer with mouth pieces
Pig specimens
Dissection trays
Dissection kits
Gloves

Part 01 Procedure: Pulmonary Ventilation

This procedure will examine how the mechanics of pulmonary ventilation occurs within a simulated lung demonstration. Collect the appropriate materials: A two liter plastic bottle, rubber bands, two straws, balloons, and modeling clay.

If the two liter plastic bottle is not cut already, please cut and remove the bottom one third of the bottle.

Attach a balloon to one end of each straw with a rubber band. From the cut end of the plastic bottle, insert the non-balloon end of the straws through the narrow opening. Place modeling clay around the straws and the top pouring spout/opening of the plastic bottle. Make sure there is no clay within the straws and the opening is completely sealed.

Take another balloon and a tie a knot within the neck region. Cut the bottom one-third of the balloon off (the other end). Then place the balloon around the bottom of the plastic bottle with the tied knotted end of the balloon facing out. Tape the balloon to the plastic bottle. (If a balloon is not big enough or stretchy enough, you may also use a plastic bag for this. Just be sure to secure all of the edges with tape.)

You have just successfully created your simulated lungs. The balloons inside of the plastic bottle are the lungs, the straws represent the trachea and bronchi, and the balloon on the bottom of the plastic bottle represents the diaphragm muscle. As you pull down on the knotted end of the balloon, note the internal balloons expand.

Describe why the internal balloons increase with air as you pull on the knotted end of the balloon (the diaphragm). Describe why the balloons deflate as you stop pulling on the knotted end of the bottom balloon (the diaphragm).