Respiration What is the main purpose of respiration? In other words why do we breathe? To provide oxygen to the body To get rid of carbon dioxide To burn food To give energy C6H12O6 + O2 H2O + CO2 + ATP (energy)

Respiration External Respiration (lung level) Respiration occurs on two levels: External Respiration (lung level) It is the process by which oxygen is delivered to the blood and carbon dioxide is removed. Internal Respiration (tissue level) It is the process by which oxygen is delivered to the cells and carbon dioxide is removed.

Respiration Processes Breathing (ventilation): air into and out of the lungs External respiration: gas exchange between air and blood Internal respiration: gas exchange between blood and tissues Cellular respiration: use oxygen to produce ATP (energy), produce carbon dioxide as waste

The Respiratory Cycle (Mechanism of Breathing)

LUNG VOLUMES Tidal Volume: the normal volume of air you breathe in and out at rest. 2. Inspiratory reserve: the maximum air you can inhale after the tidal volume. 3. Expiratory Reserve: the maximum amount of air you can exhale after exhaling your tidal volume. 4. Vital Capacity: the maximum air you can inhale and exhale (Tidal volume plus inspiratory and expiratory reserves). 5. Residual air: the air in the lungs that cannot be exhaled.

Conditioning of Inhaled Air: Several things happen to the air on its journey into the alveoli. The air is: 1. Cleansed of debris in a 2 part process. The initial cleaning is by the nose hairs and mucous in the nasal passageways. The second part of the process occurs in the trachea and bronchi which are both lined with mucous and cilia. Any material other than the gases of the inhaled air will get caught in the mucous. The cilia (microscopic protein filaments) are in constant motion, beating the debris-laden mucous up towards the pharynx. When this material is detected at the back of the mouth, it is swallowed or coughed up and expectorated (spit out). *Note: cilia do not filter! 2. Adjusted to body temperature (~37 degrees Celsius). The more contact the air has with moist tissues at 37o C, the closer the temperature of the inhaled air gets to body temperature. By the time the air arrives at the alveoli there is no difference in its temperature than that of the surrounding tissues. 3. Adjusted to 100% humidity. The air in the lungs is saturated with water. One of the things that happens to inhaled air is that as it passes over the mucous passageways, it becomes saturated with water.

Respiration The basic requirements for respiration to take place are: A respiratory surface that is big enough for the exchange of oxygen and carbon dioxide to occur at a rate sufficient to meet the organism’s metabolic needs. 2. A moist environment so that the oxygen and the carbon dioxide would dissolve. 3. Only 2 cell layers separate air in lungs from the blood

Components of the Upper Respiratory Tract

Upper Respiratory Tract Functions: Passageway for respiration Receptors for smell Filters incoming air from large foreign material Moistens and warms incoming air Resonating chambers for voice

Vocal Cords, Open

Vocal cords, closed

Components of the Lower Respiratory Tract

Lung pleural membranes

Lower Respiratory Tract Functions: Larynx: Maintains an open airway, routes food and air appropriately, assists in sound production Trachea: Transports air to and from lungs Bronchi: branch into lungs Lungs: Transport air to alveoli for gas exchange

Gas Exchange & Transport: A Passive Process Gases diffuse according to their partial pressures External respiration: gases exchanged between air and blood Internal respiration: gases exchanged with tissue fluids Oxygen transport: bound to hemoglobin in red blood cells or dissolved in blood plasma Carbon dioxide transport: dissolved in blood plasma, bound to hemoglobin, or in the form of plasma bicarbonate

Gas Exchange Between the Blood and Alveoli

Gas transport in the blood

Partial Pressures

Two molecules help the process of gas exchange become more efficient: Surfactants – these soap-like molecules, consisting of phospholipids and protein, coat the inner surface of the alveoli and reduce surface tension. Without them, the alveolar walls would stick together, making breathing very difficult. [This is one effect that cystic fibrosis sufferers have; they produce too much, very thick mucus.] B. Haemoglobin – the red oxygen-carrying molecule that fills RBC’s. Each haemoglobin molecule has four oxygen-binding sites. Most of the oxygen in blood - 98 percent – is combined with haemoglobin.

Regulation of Breathing: Nervous System Involvement Respiratory center in the medulla oblongata: The control of the breathing process is only voluntary to a point. The medulla oblongata of the brain is sensitive to the concentration of carbon dioxide and hydrogen ions in the blood. Both of these are products of cellular metabolism and both need to be excreted. As CO2 accumulates in the blood, it means that you’re not breathing fast enough, and therefore, are not getting enough oxygen. When the concentrations of H+ and CO2 reach a critical level, the breathing center in the medulla oblongata is stimulated and sends nerve impulses to the diaphragm and the intercostal muscles (that lie between the ribs) to initiate their contraction.

Carotid and aortic Vessels: *The aortic arch and carotid arteries also contain chemoreceptors that are sensitive to the oxygen content in the blood. If it is critically low, they will help initiate the inhalation response. Note, however, that this is a secondary mechanism. The primary mechanism that triggers inhalation is still an elevated concentration of carbon dioxide and hydrogen ions.

Diseases of the Respiratory System: • Asthma narrows the airways by causing allergy-induced spasms of surrounding muscles or by clogging the airways with mucus. • Bronchitis is an inflammatory response that reduces airflow and is caused by long-term exposure to irritants such as cigarette smoke, air pollutants, allergens or infectious agents. • Cystic fibrosis is a genetic defect that causes excessive mucus production that clogs the airways, also its thick nature tends to keep each alveolus sticking on itself.