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BIO 250 System and Maintainance (Plants and Animals) Chapter 2.4 Respiratory System By Mohd Azuraidi bin Harun http://yeddah.net/azuraidi/bio250 Objectives At the end of this topic, students should be able to understand about the respiratory system of a) fishes, b) insects, c) sea stars, d) birds, e) amphibians Definition ● ● ● Respiratory System – a biological system that introduces respiratory gases to the interior and performs gas exchange. In human and other mammals – respiratory system include airways, lungs, and respiratory muscles. In fishes – respiration takes place through gills. Definition ● ● In insects – respiratory system include openings called spiracles, and a network of tubes called tracheae and trachioles. In birds – respiratory system include air sacs that. ● ● Amphibians – skin plays a vital role in gas exchange. Respiratory System in Fish Gills Respiratory System in Fish ● Respiration takes place through gills. ● Gills have: ● ● ● A large surface area to allow as much oxygen to enter the gills as possible due to the fact that more gas comes into contact with the membrane, Good blood supply to maintain the concentration gradient needed, Thin membrane to allow for a short duration pathway, ● Each gill arch has two rows of gill filaments, ● Each gill filament has many lamellae. Respiratory System of Insect Respiratory System of Insect Grasshopper Caterpillar Spiracles Respiratory System of Insects ● ● ● Air enters the respiratory system of most insects through a series of external openings called spiracles. The opening acts as muscular valves. The openings lead to internal respiratory system – tracheae and trachioles. Respiratory System of Insects ● ● ● The internal respiratory system is composed of a densely networked array of tubes called tracheae. The tracheae branch repeatedly, eventually forming tracheoles. Tracheoles are blind-ended, water-filled compartments. Respiratory System of Insects ● At this level of tracheoles, the oxygen is delivered to the cells of respiration. Respiratory System of Insects ● ● ● Insects have spiracles on their exoskeletons to allow air to enter the trachea. The tracheal tubes primarily deliver oxygen directly into the animals' tissue. The spiracles can be opened and closed to reduce water loss. This is done by contracting closer muscles surrounding the spiracle. Respiratory System of Insects ● The closer muscle is controlled by central nervous system, but can react by localized chemical stimuli. Respiratory System of Sea Stars Starfish / sea star – echinoderms belonging to the class Asteriodea. The name “starfish” and “sea star” refer to this member of this class. Respiratory System of Sea Stars ● ● ● Gas exchange in sea stars occurs over their surface: they have neither gills nor lungs. Folds of skin on their dorsal surface permit gas exchange, as do the tube feet on their ventral surface. Also, they have water-based vascular system, which performs gas exchange. The starfish has a water vascular system in which the exchange between oxygen and carbon dioxide occurs. The tube feet of the starfish act like gills. The Oxygen enters the water vascular system through the tube feet as the carbon dioxide exits the body Respiratory System of Birds ` Respiratory System of Birds ● ● ● Respiration in birds is much different than in humans and in other mammals. These differences are adaptations for flight. Due to their high metabolic rate required for flight, birds have a high oxygen demand. The bird has 2 sets of air sacs: ● ● The caudal air sacs include the abdominal air sacs and the caudal thoracic air sacs. The cranial air sacs include the cervical air sac, clavicular air sac, and the cranial thoracic air sacs. ● Air enters via trachea. Half of the inhaled air enters posterior sacs, the other half passes thru the lungs and into anterior sacs. Air from anterior sacs emptied directly into trachea and out of the mouth/nares. Posterior sacs empty their air into the lungs. Air passing thru the lungs as the bird exhales is expelled via the trachea. ● ● ● A mammal's lungs are made up of millions of tiny ballons, called alveoli, which expand and contract as the animal breathes. A bird's lungs, on the other hand, are not elastic – they do not change size when bird breathes. A bird's lungs are composed of air chambers whose walls are made of a thin layer of squamous epithelium surrounded by capillaries. ● ● Specialized elastic structures called air sacs are connected to the lungs and act like furnace bellows to draw air through the lungs – very much like a furnace forces air through the ductwork of a house. As air passes through the ductwork of the lungs, O2 in the air is exchanged for CO2 in the blood of capillaries within the chamber walls. Respiratory System of Amphibians Respiratory System of Amphibians ● ● ● The lungs in amphibians are primitive: possessing a few internal septa and large alveoli, so having slow diffusion rate for oxygen entering the blood. Ventilation is accomplished by buccal pumping (breathing with one's cheeks). Most amphibians are able to exchange gases with the water or air via their skin. Respiratory System of Amphibians ● ● To enable sufficient cutaneous respiration, the surface of their highly vascularized skin must remain moist to allow the oxygen to diffuse at a sufficient high rate. Because oxygen concentration in the water increases at both low temperatures and high flow rates, aquatic amphibians in these situations can rely primarily on cutaneous respiration, as in the Titicaca water frog and the hellbender salamander. Respiratory System of Amphibians ● In air, where oxygen is more concentrated, some small species can rely solely on cutaneous gas exchange, most famously the plethodontid salamanders, which have neither lungs nor gills. ● ● Many aquatic salamanders and all tadpoles have gills in their larval stage, with some (such as the axolotl) retaining gills as aquatic adults.