Subphylum Cephalochordata clade — lancelets. Subphylum Urochordata clade — sea squirts, tunicates. Subphylum Vertebrata Craniata clade. Devonian Period called Age of Fishes because of dominance and diversity of fishes in that time.
Superclass Agnatha grade — jawless fishes. Class Myxini clade — hagfishes. Class Cephalaspidomorphi clade — lampreys. Class Chondrichthyes clade — cartilaginous fishes; sharks, skates, rays. Class Osteichthyes clade — bony fishes and their descendants grade if you leave out tetrapods. Subclass Actinopterygii clade — ray-finned fishes. Subclass Sarcopterygii clade — lobe finned fishes and their descendants grade if you leave out tetrapods.
Class Amphibia grade, although modern ones form a clade — amphibians. Carboniferous Period MYA — amphibians diversify and are the dominant terrestrial carnivores Age of Amphibians. Order Anura — frogs and toads — very derived, lost tail, modified vertebral column for jumping. Order Urodela Caudata — salamanders — elongated body with tail; moist, smooth skin. Order Apoda Gymnophiona — caecilians — lost limbs, look like worms, terrestrial or purely aquatic; burrowing.
Amniotes clade — reptiles, birds, mammals, and their relatives. Class Reptilia grade — reptiles clade if you include Aves. If particulates do make it beyond the nose, or enter through the mouth, the bronchi and bronchioles of the lungs also contain several protective devices. The lungs produce mucus —a sticky substance made of mucin , a complex glycoprotein, as well as salts and water—that traps particulates.
The bronchi and bronchioles contain cilia, small hair-like projections that line the walls of the bronchi and bronchioles Figure. These cilia beat in unison and move mucus and particles out of the bronchi and bronchioles back up to the throat where it is swallowed and eliminated via the esophagus. In humans, for example, tar and other substances in cigarette smoke destroy or paralyze the cilia, making the removal of particles more difficult.
In addition, smoking causes the lungs to produce more mucus, which the damaged cilia are not able to move. This causes a persistent cough, as the lungs try to rid themselves of particulate matter, and makes smokers more susceptible to respiratory ailments. Section Summary Animal respiratory systems are designed to facilitate gas exchange.
In mammals, air is warmed and humidified in the nasal cavity. Air then travels down the pharynx, through the trachea, and into the lungs. In the lungs, air passes through the branching bronchi, reaching the respiratory bronchioles, which house the first site of gas exchange.
The respiratory bronchioles open into the alveolar ducts, alveolar sacs, and alveoli. Because there are so many alveoli and alveolar sacs in the lung, the surface area for gas exchange is very large. Several protective mechanisms are in place to prevent damage or infection. These include the hair and mucus in the nasal cavity that trap dust, dirt, and other particulate matter before they can enter the system.
In the lungs, particles are trapped in a mucus layer and transported via cilia up to the esophageal opening at the top of the trachea to be swallowed. Figure Which of the following statements about the mammalian respiratory system is false? Describe the function of these terms and describe where they are located: main bronchus, trachea, alveoli, and acinus. The main bronchus is the conduit in the lung that funnels air to the airways where gas exchange occurs.
The main bronchus attaches the lungs to the very end of the trachea where it bifurcates. The trachea is the cartilaginous structure that extends from the pharynx to the primary bronchi.
It serves to funnel air to the lungs. The alveoli are the sites of gas exchange; they are located at the terminal regions of the lung and are attached to the respiratory bronchioles. The acinus is the structure in the lung where gas exchange occurs. The sac-like structure of the alveoli increases their surface area.
In addition, the alveoli are made of thin-walled parenchymal cells. These features allow gases to easily diffuse across the cells. Skip to content The Respiratory System. Learning Objectives By the end of this section, you will be able to do the following: Describe the passage of air from the outside environment to the lungs Explain how the lungs are protected from particulate matter.
The cell of the unicellular alga Ventricaria ventricosa is one of the largest known, reaching one to five centimeters in diameter. Like all single-celled organisms, V. This common carp, like many other aquatic organisms, has gills that allow it to obtain oxygen from water. As water flows over the gills, oxygen is transferred to blood via the veins.
Insects perform respiration via a tracheal system. Visual Connection. Air enters the respiratory system through the nasal cavity and pharynx, and then passes through the trachea and into the bronchi, which bring air into the lungs. The trachea and bronchi are made of incomplete rings of cartilage.
The trachea bifurcates into the right and left bronchi in the lungs. The right lung is made of three lobes and is larger. To accommodate the heart, the left lung is smaller and has only two lobes.
Terminal bronchioles are connected by respiratory bronchioles to alveolar ducts and alveolar sacs. Each alveolar sac contains 20 to 30 spherical alveoli and has the appearance of a bunch of grapes. Air flows into the atrium of the alveolar sac, then circulates into alveoli where gas exchange occurs with the capillaries. Mucous glands secrete mucous into the airways, keeping them moist and flexible. Link to Learning. Protective Mechanisms The air that organisms breathe contains particulate matter such as dust, dirt, viral particles, and bacteria that can damage the lungs or trigger allergic immune responses.
The bronchi and bronchioles contain cilia that help move mucus and other particles out of the lungs. When we breathe in, air travels from the pharynx to the trachea.
The bronchioles branch into bronchi. Alveolar ducts connect to alveolar sacs. Gas exchange between the lung and blood takes place in the alveolus.
Clarendon Press, Oxford. Carlisle, D. Vanadium and other metals in ascidians. B, , Eyring, H. Laidler, H. Glasstone, p McGraw-Hill, New York. Laurent, T. On the interaction between polysaccharides and other macromolecules: Transport of globular particles through hyaluronic acid solution. Acta 78, Diffusion of linear polymers in hyaluronate solution. MacDougall, J.
Diffusion coefficient of oxygen through tissues. Natures ,
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