Elena AntonBio 120Professor: RashidahAbdullah

Respiratory System

Cells continually use oxygen for the metabolic reactions that releases energy from nutrient molecules and produce ATP. At the same time , these reaction release carbon dioxide . Because an excessive amount of carbon dioxide produces acidity that can be toxic to cells, excess carbon dioxide must be eliminated quickly and efficiently.

The two system that cooperate to supply oxygen to and eliminate carbon dioxide from body cells are the respiratory and cardiovascular system. The respiratory system is responsible for gas exchange –intake of oxygen and elimination of carbon dioxide. In addition to functioning in gas exchange , the respiratory system also participates in regulating blood pH , contains receptors for the sense of smell, filters inhaled air , produces sound, and rids the body of small amounts of water and heat in exhaled.

The respiratory system consists of the nose, pharynx, larynx , trachea, bronchi, and lungs. They act with the cardiovascular system to supply oxygen to remove carbon dioxide from the blood.

The external portion of the nose is made of cartilage and skin and is lined with a mucous membrane . Openings to the exterior are the external nares. The internal portion of the nose communicates with paranasal sinuses and nasopharynx through the internal nares. The nasal cavity is divided by a septum. The anterior portion of the cavity is called a vestibule . The nose warms ,moistens , and filters air and functions in olfaction and speech.

The pharynx (throat) is a muscular tube lined by a mucous membrane. The anatomic regions are the nasopharynx , oropharynx and laryngopharynx. The nasopharynx functions in respirations, the oropharynx and laryngopharynx function both in digestion and in respiration .

The larynx (voice box) is a passageway that connects the pharynx with the trachea . it contains the thyroid cartilage ,the epiglottis which prevents food from entering the larynx , the cricoid cartilage which connects the larynx and trachea, and the paired arytenoid , corniculate, and cuneiform cartilages. The larynx also contains the vocal folds , which produces sound as they vibrate, taut folds produces high pitches and relaxed ones produce low pitches.

The trachea extends from the larynx to the primary bronchi . It is composed of C-shape rings of carlitage and smooth muscle and is lined with pseudostratified ciliated columnar epithelium. The bronchial tree consist of the trachea , primary bronchi, secondary bronchi, tertiary bronchi, bronchioles, and terminal bronchioles. Walls of bronchi contain increasingly smaller plates of cartilage and increasing amount of smooth muscle.

Lungs are paired organs in the thoracic cavity enclosed by the pleural membrane. The parietal pleural is the superficial layer that lines the thoracic cavity , the visceral pleural is the deep layer that covers the lungs .

The right lung has three lobes separated by two fissures, the left lung has two lobes separated by one fissure , along with a depression , the cardiac notch.

Secondary bronchi gives rise to branches called segmental bronchi, which supply segments or lung tissue called bronchopulmonary segments. Each bronchopulmonary segment consists of lobules , which contain lymphatics , arterioles , venules , terminal bronchioles , respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli. Alveolar walls consist of type I alveolar cells and type II and associated alveolar macrophanges.

Regulation of Respiration

The respiratory center consist of medullary rhythmicity area a pneumotaxic area and an apneustic area. The inspiratory area sets the basic rhythm of respiration. The pneumotaxic and apneustic areas coordinate the transition between inspiration and expiration.

THE END