Human Biology: Respiratory System Lesson 2: Processes of the Respiratory System (Inquiry into Life pg )

Today’s Objectives  Analyse the processes of breathing, including:  Describe the interactions of the following structures in the breathing process: respiratory centre in the medulla oblangata, lungs, pleural membranes, diaphragm, intercostal (rib) muscles, stretch receptors  Compare and contrast the processes of inhalation and exhalation  Explain the roles of CO2 and H ions in stimulating the respiratory centre in the medulla oblongata  Explain the roles of oxygen, CO2, and H ions in stimulating carotid and aortic bodies  Analyse internal and external respiration, including:  Describe the exchange of CO2 and O2 during internal and external respiration, including location of exchange and conditions that favour exchange  Explain the roles of oxyhemoglobin, carbaminohemoglobin, reduced hemoglobin, bicarbonate ions, and carbonic anhydrase in the transport of CO2 and O2 in the blood  Write the chemical equations for internal and external respiration

Processes of the Respiratory System  The respiratory system supplies the body with oxygen for its energy production  Without oxygen, the body shuts down in minutes  The respiratory system works closely with the circulatory system

Four Processes make up the Resp. System  A) Breathing:  Inspiration – bringing oxygen into the lungs  Expiration – expelling carbon dioxide  B) External Respiration:  Exchange of gases between blood and the lungs  C) Internal Respiration:  Exchange of gases between blood and the body tissues  D) Cellular Respiration:  Production of ATP energy within the cells  Let’s focus on cellular respiration first!...you need to memorize ALL of the next slide. Study hard…

Just kidding ;)

A) Breathing  Pleural Membranes:  2 sets of membranes:  A) one joined to the lung  B) one joined to the ribs and diaphragm  The two sets are close together separated by a slight amount of fluid (vacuum is created)  If the membranes are punctured, air enters the interpleural space, destroying the vacuum. The lung collapses  They maintain an interpleural pressure that is less than atmospheric pressure, keeping the lungs open

Mechanisms of Breathing: Inhalation and Exhalation  The chest cavity is dome-shaped  The top and sides are surrounded by the ribs  The bottom is made up by the diaphragm  It is a closed system

Inhalation  1) CO2 concentration and H+ concentration are the PRIMARY STIMULI that cause us to breathe  When CO2 and/or H+ concentration gets too high, the breathing center in the Medulla Oblongata is stimulated  2) A nerve impulse is sent from the Medulla Oblongata to the diaphragm and rib cage  3) The diaphragm contracts and lowers; the intercostal (rib) muscles contract and raise the ribs  4) A partial vacuum is created in the lungs (air pressure in the lungs is reduced) due to the increased volume of the chest cavity

Inhalation  5) Air rushes into the lungs from outside in order to rebalance the pressure  This is the process of inspiration  Note: air comes in because the lungs have already opened. The air does not force the lungs open. This is why it is said we breathe by negative pressure (low pressure sucks the air into our lungs)  Note: The lungs themselves have no muscles

Exhalation  1) When the lungs are full, stretch receptors in the alveoli are stimulated  2) The Medulla Oblongata is notified and stops sending messages  3) The diaphragm and rib muscles relax  4) The chest cavity gets smaller, decreasing volume, which increases the pressure in the lungs: air is forced out

Other Receptors  In addition to the respiratory center in the Medulla Oblongata, there are other receptors that can respond to stimuli:  A) carotid bodies – in the carotid artery  B) aortic bodies – in the aorta  These respond to low oxygen concentration but can also respond to levels of CO2 and H+ ions in the blood

Who has the largest lung capacity?  We are going to go to the 1 st floor Bio lab and find out our lung capacity using a Spirometer  We take as deep a breath as possible, then blow allllll of the air in our lungs into the mouthpiece of the spirometer  The spirometer has a gauge on the side that indicates your lung capacity

2) Gas Exchange  When CO2 diffuses from the cells into the blood, only a small amount of it (9%) is held in simple solution (as dissolved CO2)  Another 27% attaches directly to the Hemoglobin to form carbaminohemoglobin (carbonaminohemoglobin)  The remaining 64% combines with water to form bicarbonate ions and hydrogen ions

Gas Exchange  Each time blood passes through the tissues, it picks up large quantities of CO2.  This then reacts with water to form bicarbonate (HCO3- ) and hydrogen (H+) ions  There are many substances in the blood capable of binding the excess free hydrogen ions  Hemoglobin is one of the most important of these substances  When hydrogen (H+) combines with the hemoglobin (Hb), the Hb releases some of the oxygen attached to it

Gas Exchange in Tissues Internal Respiration

1. CO 2 diffuses into the blood from the cell

2. CO 2 joins with water to make Bicarbonate and Hydrogen Ions. Carbonic anhydrase is the enzyme that runs this reaction

3. Most of the released H + is picked up by the combined form of O 2 and hemoglobin, Oxyhemoglobin [HbO 2 ]. The binding of H + by HbO 2 (produces HHb) aids in the release of oxygen. The H + concentration (pH) and the slight increase in temperature alter the hemoglobin (protein denatures slightly) and releases oxygen easily.

4. Oxygen then enters the tissue moving from an area of high concentration to areas of low concentration.

The blood leaving the tissues now contains large quantities of hemoglobin which is free of oxygen, and is called Reduced Hemoglobin (HHb). The blood also contains large amounts of bicarbonate ions (HCO 3 - ). No further changes occur until the blood reaches the lungs.

Gas Exchange in the Lungs External Respiration

1. High concentration of Oxygen in lungs. Oxygen diffuses into blood..

2. Oxygen joins with reduced hemoglobin to form Oxyhemoglobin and Hydrogen ions.

3. H + picked up by Bicarbonate to produce CO 2 + H 2 O

4. The CO 2 diffuses into lung alveoli where it is expelled by normal breathing.

External Respiration  Note: H+ does not accumulate because as soon as it is released from HHb, it combines with HCO3- to release CO2  Hemoglobin is essential in the blood because it serves as a carrier for O2, CO2, and H+ ions (acts like a buffer)  H+ concentration (pH) and decrease in temperature in lungs allows hemoglobin to regain its original shape, allowing it to bind with oxygen easier

Respiratory Rap!  Song lyrics sheet:  Due Monday, April 22  Videos/Presentations:  In class on Friday, April 26 *Groups of 3 to 5 List group members on your lyrics sheet