Friday, March 27, 2009

Chapter 42 (extra notes)

Okay so in class on March the 19th we went over our take home quiz on Chapters 40,41, and 42, also we started on the packet of the Chi square, also the Invertebrate Activity.
Also I found this awesome video that describes all of the notes we took on 42. It doesn't get into great detail but it gives a great outline on the notes.

Few extra notes on Circulation and Gas Exchange:

All animal cells go through cellular respiration, which is the breakdown of energy into a usable form to provide power to perform cellular functions. Oxygen is required for that of cellular respiration, resulting in carbon dioxide as a waste product. Animals, therefore, use an organ system in which the exchange of oxygen and carbon dioxide can take place with the external environment, as well as a system to transport these gases throughout the body. The respiratory and circulatory systems perform these two intertwined tasks. The respiratory system exchanges gases with the environment, while the circulatory system transfers those gases throughout the body.

All gas exchange requires a moist medium for the gases to move from surface to surface. This requirement poses no problem for animals living only in aquatic environments, as gills and skin absorb gases directly from the surrounding water. However, as animals evolved to live on land, they developed tracheae and lungs that contained moist surfaces for this purpose. The following table describes each respiratory structure in more detail.

In a process known as cutaneous respiration, the skin, which is moist and well-vascularized, exchanges gas directly with the environment through its blood vessels.

Amphibians, such as frogs and salamanders, as well as some marine snakes, respire through their skin. This usually takes place in conjunction with respiration through lungs.

Gills are extensions of internal tissues that project into the water, where gases can diffuse. Gills are heavily branched, providing a large amount of surface area for gas to exchange, making them more efficient than skin. Gills can be external (not enclosed in the body), which requires constant movement to ensure contact with fresh water, or internal, enclosed within branchial chambers where water is pulled in and out, creating currents over the gill tissue.

External gills are found on the larvae of many fish and amphibians, as well as adult amphibians such as the axolotl. Internal gills are found in arthropods such as crustaceans and spiders, mollusks, echinoderms many adult amphibians, and fish.

Tracheae are air-filled tubular passages that form an extensive network in the body. These passages connect the body surface with all internal structures. Oxygen is passed straight from the tracheae into cells. Insects rely solely on this respiratory system, rather than a circulatory system, to transfer oxygen throughout their bodies. Insects have external structures on their exoskeleton called spiracles that open and close to prevent water loss during respiration.

Tracheae are the respiratory system of most terrestrial arthropods, including all insects, some spiders, mites and ticks, millipedes, and centipedes.

Air moves into and out of the body through branched tubular passageways, which moisten the air in the process. Eventually moist air reaches a thin, wet membrane that permits exchange of gases within the lungs, where it can be circulated throughout the body.

Lungs are found in some arthropods, as well as all amphibians, reptiles, birds, and mammals.

1. As blood returns to the human heart from systemic capillaries, the blood will first enter the:
A. left atrium

B. right atrium
C. left ventricle

D. right ventricle

E. aorta

2. Which of the following are the only vertebrates in which blood flows directly from respiratory organs without first returning to the heart?
A. Amphibians

B. Birds

C. Fishes
D. Mammals

E. Reptiles

3. Tracheal systems with gas exchange are found in:
A. crustaceans

B. earthworms

C. insects
D. jellyfish

E. vertebrates

Answers: 1: B,2:C,3:C.

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