Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings.

CHAPTER 10

RESPIRATORY SYSTEM:

EXCHANGE OF GASES

PowerPoint® Lecture Slide Presentation by Robert J. Sullivan, Marist College

Human Biology

•O2 is vital to life! Humans can survive for only a few minutes without oxygen (3-4 minutes is enough to cause some brain damage). Needed in most chemical reactions in our body (cellular respiration) •Air is 78% nitrogen, 21% oxygen, and 1% other gases including carbon dioxide

•We take between 17000 and 29000 breaths everyday. It happens subconsciously and we can stop breathing momentarily, but it resumes automatically regardless of how hard you try

The Need for Oxygen:

The two main functions of the respiratory system is to provide O2 from the ambient (outside) air to the blood and to pick up waste gas, CO2 from the blood and transport it out of the body

Function:

O2 CO2

Other functions of respiratory system include protecting body from microorganisms: -cells of trachea secrete mucous that can trap foreign objects that were not

stopped in nasal cavity -microscopic cilia then work to “sweep” out trapped substances back to the pharynx -once in pharynx these substances can be swallowed or expelled

Respiratory system also provides sound by vocal cords (in larynx) – these cords vibrate as air is forced past them, producing sound

Other Functions:

•Aerobic cellular respiration: the series of chemical reactions that occur in the cell that provide energy and consume oxygen

•C6H12O6 + 6O2 6CO2 + 6H2O + energy Glucose + oxygen carbon dioxide + water + energy • About 64% of our energy is released as thermal energy created during respiration, the rest is stored as ATP (adenosine triphosphate). 36 ATP are made for every glucose molecule

Aerobic Cellular Respiration

Making ATP •Cells use ATP to power most all energy requiring reactions like active transport and building new molecules •C6H12O6 + 6O2 + 36 ADP + 36 Pi 6CO2 + 6H2O + 36 ATP + thermal energy

Gas Exchange:

•The process by which oxygen diffuses into the body cells and carbon dioxide diffuses out of the cells

•External respiration (lungs and environment) •Oxygen diffuses from the air into the blood stream

•Internal respiration (blood and cells) •Oxygen diffuses from the blood stream into the cells through interstitial fluid (fluid surrounding all cells)

•Carbon dioxide follows the reverse •Ventilation (breathing): the process of moving oxygen-rich air into the lungs and carbon dioxide rich air out of the lungs

Human Respiratory System

Alveoli

R lung L lung

Components of the Upper Respiratory Tract

Figure 10.2

•1. A thin permeable membrane through which diffusion can occur

•Alveoli have a membrane that is 1 cell thick

2. A large surface area for gas exchange

• There are 150 million alveoli per lung

3. A breathing system for bringing in oxygen-rich air to the respiratory membrane

• Lungs assisted by diaphragm and intercostal muscles

4. Large blood supply

• capillaries surround alveoli

Requirements for Function:

Structure:

•Passage:

•Nasal cavity or mouth, to the pharynx, to the trachea and moves down the trachea into lungs. Within the lungs the air moves into the bronchi, which branch into bronchioles and into alveoli.

•Air is warmed and moistened in the nose and mouth before entering the lungs so as to prevent damage to the thin delicate tissue. Cilia and mucus in nose filter dust, bacteria and other air borne particles

Structure:

Trachea: a semi-rigid tube of soft tissue, wrapped around c-shaped bands of cartilage that leads from the mouth towards the lungs. Lined with cells that have cilia and produce mucus. Cilia: tiny hair-like structures that are found on some cells ( ex. Trachea, lungs and nose)

•wavelike motions of the cilia sweep the trapped material upward through the trachea where it is swallowed or expelled through coughing or sneezing

Lungs: •Enclosed in the thoracic (chest) cavity and are protected by the ribs •Provide respiratory membranes, large surface area and have a good supply of blood

Components of the Lower Respiratory Tract

Figure 10.3

Structure: Bronchi: the trachea branches into two bronchi (singular: bronchus) Bronchioles: the bronchi repeatedly branch into smaller and smaller tubes called bronchioles Alveoli: airway end in clusters of tiny sacs called alveoli that form the respiratory membrane. Each cluster is surrounded by a network of capillaries. Each alveolus is tiny measuring (0.1 to 0.2 micrometers in diameter). There are approximately 150million in each lung

•If the entire surface area of our lungs was flattened out it would cover a tennis court

Gas Exchange Between the Blood and Alveoli

Figure 10.8A

•Air is at 37C. •Moist air is critical as diffusion cannot occur until gas is dissolved in a liquid

Respiratory membrane is 1 cell thick

Mechanism of ventilation:

breathing…..

•Based on the principle of NEGATIVE PRESSURE

•When lungs have a lower pressure than atmospheric pressure, air is forced in •When air pressure is higher in the lungs air is forced out

•Diaphragm: large dome shaped sheet of muscle beneath the lungs that facilitates breathing.

•INHALATION: diaphragm contracts (negative pressure) •EXHALATION: diaphragm relaxes (positive pressure)

External Intercostal muscles: during inhalation these muscles between each rib, pull the ribs outward and upward. This INCREASES volume and DECREASES pressure Internal intercostal muscles: are a second set of muscles that start to contract and relax during strenuous exercise

Ventilation:

Pleural membranes: a thin layer of connective tissue that covers the outer surface of the lungs and lines the thoracic cavity. Prevents friction between lungs and thoracic cavity Pleural cavity: the space between the pleural membranes. Filled with fluid to prevent the membranes from separating, but still slide past one another (like 2 wet slides). Pneumothorax: a collapsed lung caused by the introduction of air between the pleural membranes

Respiratory Cycle

Figure 10.9

Lung Capacity: with a spirometer

Total lung capacity: the maximum volume of air that can be inhaled during a single breath Tidal volume: the volume of air inhaled or exhaled during a normal, involuntary breath Inspiratory reserve volume: the volume of air that can be forcibly inhaled after normal inhalation Expiratory reserve volume: the volume of air that can be forcibly exhaled after normal exhalation Residual volume: the volume of air remaining in the lungs after forced exhalation Vital capacity: the maximum amount of air that can be inhaled or exhaled

Factors Affecting Lung Capacity

Figure 10.10A

Larger volumes Smaller volumes

males females

taller people shorter people

non-smokers heavy smokers

professional athletes non-athletes

people living at high altitudes people living at low altitudes

Oxygen usage:

• physical activity depends on the energy released during aerobic cellular respiration and this depends on the supply of oxygen

•A high maximum rate of oxygen usage(the rate at which oxygen can be used in cellular respiration) indicates an efficient respiratory system

•VO2 : an estimated or measured value representing the rate at which oxygen is used in the body. (ml/kg/min) •VO2max: the maximum rate at which oxygen can be used in an individual (ml/kg/min); during exercise

Spirometer:measuring oxygen usage efficiency

and lung capacity

Oxygen usage efficiency depends on gender, age and fitness