*The respiratory system consists of tubes that filter incoming air and transport it into the microscopic alveoli where gases are exchanged the entire process of exchanging gases between the atmosphere and body cells is called respiration and consists of the following: ventilation, gas exchange between blood and lungs, gas transport in the bloodstream, gas exchange between the blood and body cells, and cellular respiration *The organs of the respiratory tract can be divided into two groups: the upper respiratory tract (nose, nasal cavity, sinuses, and pharynx), and the lower respiratory tract (larynx, trachea, bronchial tree, and lungs).
*The pharynx is a common passageway for air and food.
The pharynx aids in producing sounds for speech.
*The larynx is an enlargement in the airway superior to the trachea and inferior to the pharynx.
It helps keep particles from entering the trachea and also houses the vocal cords.
The larynx is composed of a framework of muscles and cartilage bound by elastic tissue.
Inside the larynx, two pairs of folds of muscle and connective tissue covered with mucous membrane
The upper pair is the false vocal cords. The lower pair is the true vocal cords
During swallowing, the false 6 cords and epiglottis close off the glottis
* The trachea extends downward anterior to the esophagus and into the thoracic cavity, where it splits into right and left bronchi.
The inner wall of the trachea is lined with ciliated mucous membrane with many goblet cells that serve to trap incoming particles.
*The bronchial tree consists of branched tubes leading from the trachea to the alveoli.
The bronchial tree begins with the two primary bronchi, each leading to a lung.
The branches (Figs. 16.8-16.9) of the bronchial tree from the trachea are right and left primary bronchi; these further subdivide until bronchioles give rise to alveolar ducts which terminate in
Avioli .It is through the thin epithelial cells of the alveoli (Fig. 16.10) that gas exchange between the blood and air occurs.
*The right and left soft, spongy, cone-shaped lungs are separated medially by the mediastinum and are enclosed by the diaphragm and thoracic cage.
The bronchus and large blood vessels enter each lung.
A layer of serous membrane, the visceral pleura, folds back to form the parietal pleura.
The visceral pleura is attached to the lung, and the parietal pleura lines the thoracic cavity; serous fluid lubricates the “pleura cavity” between these two membranes.
The right lung has three lobes, the left has two.
Each lobe is composed of lobules that contain air passages, alveoli, nerves, blood vessels, lymphatic vessels, and connective tissues.
*The alveoli are the only sites of gas exchange between the atmosphere and the blood.
*Gases are transported in association with molecules in the blood or dissolved in the plasma.
Oxygen Transport (Fig. 16.21)
Over 98% of oxygen is carried in the blood bound to hemoglobin of red blood cells, producing oxyhemoglobin.
Oxyhemoglobin is unstable in areas where the concentration of oxygen is low, and gives up its oxygen molecules in those areas.
More oxygen is released as the blood concentration of carbon dioxide increases, as the blood becomes more acidic, and as blood temperature increases. A deficiency of oxygen reaching the tissues is called hypoxia and has a variety of causes.
*The urinary system consists of two kidneys that filter the blood, two ureters, a urinary bladder, and a urethra to convey waste substances to the outside.
*A medial depression in the kidney leads to a hollow renal sinus into which blood vessels, nerves, lymphatic vessels, and the ureter enter.
Inside the renal sinus lies a renal pelvis that is subdivided into major and minor calyces; small renal papillae project into each minor calyx.
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