2.1 Structure and Function of the Ventilatory System PDF

2.1 Structure and function of the ventilatory system http://napavalley.edu/people/bmoore/PublishingImages/P ages/Histology-Page/Diaphragm%20100X.bmp The principal structures of the ventilatory system Ventilatory system The nasal passages and lungs Air is drawn into the body via the nose or mou...

2.1 Structure and function of the ventilatory system http://napavalley.edu/people/bmoore/PublishingImages/P ages/Histology-Page/Diaphragm%20100X.bmp The principal structures of the ventilatory system Ventilatory system The nasal passages and lungs Air is drawn into the body via the nose or mouth. Theretheare airadvantages is warmedto sobreathing that it is through yourcloser nose:to body temperature tiny hairs and mucus in the nose filter the air, preventing larger dust and pollen particles reaching the alveoli mucus moistens the air, making Air then it easier travels for the through the alveoli larynx, trachea to absorb. (windpipe), bronchi (one bronchus to each lung) and bronchioles to the alveoli, where oxygen passes into the bloodstream.  Pharynx (throat) The place where the nasal cavity, esophagus and trachea meet Pharynx Epiglottis is a flap of tissue covering the glottis (tracheal opening) that preventing food from tps://www.cdli.ca/courses/biol2201/unit03_org03_ilo02/8_12_cap.jpg Epiglottis What if food mistakenly enter the windpipe?? The Heimlich maneuver can save lives Figure 33-8 object ejected lungs compressed Grasp the hands between the navel diaphragm and breastbone pushed upward Quickly and forcefully pull upward and toward your body Larynx (voice box) Houses the vocal cords Vibrations of the cords produces sound Larynx Larynx (voice box) http://www.sciencephoto.com/image/309652/530wm/P4960012-Resting_larynx-SPL.jpg Cartilage Trachea and bronchus walls are composed of C- shaped cartilage (soft bone) The rings of cartilage prevents the trachea and bronchus from collapsing during inhalation Structure of the lungs Keeping the airways clear The walls of the trachea and bronchus contain goblet cells, which secrete mucus made of mucin. This traps micro- organisms and debris, helping to keep the airways The walls also contain ciliated epithelial clear.which are covered on one surface with cells, cilia. These beat regularly to move micro- organisms and dust particles along with the mucus. They contain many mitochondria to Mucus and cilia MUCUS AND CILIA Gas exchange in the alveoli Gas exchange in the alveoli Alveoli have thin walls from the to the pulmonary vein pulmonary to bring air and blood artery as close as possible The inner surface of the capillary alveoli is covered with capillary a thin layer of moisture walls alveolar so gases are dissolved wall (air) making diffusion easier. Oxygen diffuses into Carbon dioxide diffuses the red blood cells into the alveolus How are alveoli adapted? Alveoli have several adaptations that help to make gas exchange very efficient:  They are very thin – only one cell thick.  They are covered by a network of fine capillaries, a rich blood supply maintains a high concentration gradient of O2 and CO2  They are moist, encouraging gas molecules to easily dissolve.  They have a large combined surface area, allowing large amounts of gases to be exchanged with each breath. The functions of the conducting airways. low resistance pathway for airflow defence against chemicals and other harmful substances that are inhaled warming and moistening the air. Lungs Your lung is soft and spongy. They expand as you breath in and contract as you breath out. Intercostal Muscles Intercostal Intercostal muscles muscles are bands of muscles between your ribs Diaphragm  large muscle located between abdominal and chest cavities  Dome shaped sheet of muscle and tendon that plays a vital role in the breathing process Mechanics of breathing Fig. 19.21 Gas will move along a gradient from an area of higher partial pressure to lower partial pressure. Model of ventilation MODELLING MECHANISM OF BREATHING The mechanics of ventilation in the human lung Intercostal Muscles  The mechanics of ventilation in the human lung Inspiration Expiration s pressure change decrease in pressure increase in pressure se se au (draws air inwards) (pushes air outwards) c volume change increase decrease s u ribcage movement up and outward down and inward ca external intercostal contract relax muscles internal intercostal relax contract muscles diaphragm contract relax (flattens, moves downwards) abdominal muscles relax contract (pushes the diaphragm up) diagrams http://media1.shmoop.com/images/biology/biobook_animalmovement_graphik_36.png Accessory muscles aid in ventilation during exercise At rest, the exhalation (breathing out) process is passive (no energy required) as the diaphragm relaxes and therefore recoils back to its original position without any conscious muscular work. However, during exercise when more oxygen is needed by the active muscles and more carbon dioxide is being produced by the muscles, more air needs to be inhaled and exhaled at a faster rate. To achieve this, some additional muscles in the chest wall (external intercostal muscles), abdomen, and even the shoulders, can assist with increasing the lung volume during inhalation. Furthermore, contraction of these muscles during exhalation will also compress the lungs faster and more forcefully than the natural recoil. This is therefore an active process, requiring energy to fuel the muscles of the chest and abdomen. Accessory muscles aid in ventilation during exercise Pulmonary ventilation is inflow and outflow of air between the atmosphere and the lungs (also called breathing). Tidal volume is the volume of air breathed in and out in any one breath. ERV Inspiratory reserve volume Residual Volume Vital capacity Total Lung Capacity Spirometry Spirometry Spirometry SUMMARY Pulmonary ventilation: inflow and outflow of air between the atmosphere and the lungs (also called breathing). Total lung capacity: volume of air in the lungs after a maximum inhalation. Vital capacity: maximum volume of air that can be exhaled after a maximum inhalation. Tidal volume: volume of air breathed in and out in any one breath. Expiratory reserve volume: volume of air in excess of tidal volume that can be exhaled forcibly. Inspiratory reserve volume: additional inspired air over and above tidal volume. Residual volume: volume of air still contained in the lungs after a maximal exhalation. Nervous and chemical control of ventilation during exercise. During exercise metabolism is increased, which results in a build up of carbon dioxide which would cause an increases in blood acidity levels (low pH) These changes are detected by chemoreceptors and impulses are sent to the respiratory control centre in the brainstem (Medulla Oblongata) o Signals are sent to the diaphragm and intercostal muscles to increase the rate and depth of ventilation (this process is involuntary) o As the ventilation rate increases, CO2 levels in the blood will drop, restoring blood Nervous and chemical control of ventilation during exercise. Nervous and chemical control of ventilation during exercise. Neural control of ventilation includes lung stretch receptors, muscle proprioceptors and chemoreceptors. Nervous and chemical control of ventilation during exercise. Red blood cells and haemoglobin Most (98.5%) of oxygen in the blood is transported by hemoglobin as oxyhemoglobin within red blood cells. At high oxygen concentrations oxyhaemoglobin forms At low oxygen concentrations oxyhaemoglobin + dissociates to haemoglobin and oxygen oxyge n oxyhaemoglob haemoglobi in n haemoglobi oxyhaemoglob + n in oxyge n Haemoglobin Haemoglobin is a protein making up 95% of the dry mass of a red blood cell. It is the means of transport of oxygen around the body. Haemoglobin is made up of four polypeptide chains, each bound to one haem group. Each haem group can combine with one oxygen molecule, so that one molecule of haemoglobin can combine with a Polypeptide maximum of four chain oxygen molecules. Partial Pressure The concentration of a gas in a mixture of gases can be quantified in terms of its partial pressure. This is the amount of pressure exerted by the gas relative to the total pressure exerted by all the gases in the mixture. Partial pressure is measured in kilopascals (kPa) and is written as P(O2), P(CO2), etc. Partial pressure differences between lungs, blood and tissues Gas exchange is continuously occurring between air, blood and tissue. Gases move by a passive process called diffusion along a gradient from high pressure to low pressure. Partial pressure differences between lungs, blood and tissues Partial pressure differences between lungs, blood and tissues