Human Biological Systems, Gas Exchange & Transport - Assignment Example

Overall, this CNS control determines the depth and frequency of the respiration. (Schwartzstein & Parker, 2006, p.3) 2. Ventilatory Pump a) Muscles of respiration: there are two sets of muscles that are classified either muscles of inspiration or muscles of expiration. Diaphragm and external intercostal muscles are muscles of inspiration whereas internal intercostal muscle is the muscle of expiration. There are some accessory muscles that assist in forceful inspiration or expiration such as sternocleidomastoid, scalenus, pectoralis and abdominal muscles. b) Chest wall skeleton: rib cage provides the major skeleton support for lungs. c) Chest wall connective tissue: d) Airways: nares (nose), larynx, trachea, bronchus and bronchioles. e) Pleura: visceral pleura and parietal pleura. f) Spinal cord and peripheral nerves: C3, C4 and C5 spinal segments provide innervations to diaphragm via phrenic nerve.

All the intercostal muscles get segmental innervations through intercostal nerves that run in the intercostal groove along with artery and vein. Most of the structures of Ventilatory pump, such as muscles and skeleton, ensure appropriate movement of the chest wall and adequate change in the intrathoracic pressure during inspiration and expiration. All the components of airway provide an uninterrupted passage of air to and from the alveoli. The passage is also lined with special epithelium that produces mucus and is studded with cilia (Hlastala & Berger, 1996, p.23). Mucus moist or warm the air whereas cilia traps any foreign particles and clear excess mucus.

Parietal pleura line the chest wall and visceral pleura cover the outer surface of the lung. In between these two layers is a pleural space that contains a small amount of fluid. This pleural space plays a critical role in changing the intrathoracic pressure. Spinal cord and peripheral nerves provide a communication between controller and muscles of respiration. (Schwartzstein & Parker, 2006, p.15-23) 3. Gas Exchanger a) Alveoli: the terminal bronchioles are studded with hollow grape like structures called alveoli. b) Pulmonary capillaries: these capillaries originate from the branches of pulmonary artery and aggregate to form pulmonary vein.

Terminal bronchioles and alveoli are the sites of gas exchange (no gas exchange take place in the rest of the airway and is referred to as dead space). These alveoli provide abundant surface area for adequate diffusion of gases. Understandably, alveoli are surrounded by thousand of blood capillaries to ensure effective transfer of oxygen and carbon dioxide. TAQ 2: 1. Using annotated diagrams explain the processes involved in breathing in and out. Fig 2.1: shows the process of breathing and the structures involved.

Breathing In: The process of breathing in is called inspiration. There are two important muscles, diaphragm and external intercostal muscles, that take part in this process. When a person breathes in, diaphragm contracts and chest expands increasing volume of the thoracic cavity and creating a negative intrathoracic pressure (fig 2.1). Therefore, air flows from a relatively positive atmospheric pressure towards the negative intrathoracic pressure and fill both lungs. Breathing Out: The process of breathing out is called expiration.

Unlike inspiration, expiration at rest is a passive process and do not require muscle support. In fact, the elastic recoil