Tuesday, March 17, 2009

Chapter 41 continued../Chapter 42

-The large intestine, also called the colon, is connected to the small intestine by a sphincter. The point of the connection is the site of the cecum, a small pouch with an extension called the appendix.
-The main function of the large intestine is to compact waste and recover water from it that can be returned to the body. The wastes become more solid as they travel along and form feces.
-At the end of the colon is the rectum, where feces are stored until they are eliminated.
-Evolutionary adaptions of vertebrate digestive systems correlate with diet.
-A mammal's dentition is generally correlated with its diet. In particular, mammals have specialized dentition that best enables them to ingest their food.
-Herbivores generally have longer alimentary canals. carnivores, reflecting the longer time needed to digest vegetation. Much of the chemical energy in herbivore diets comes from the cellulose of plant cell walls Many vertebrates (as well as termites) house large populations of symbiotic bacteria and protists whose enzymes actually digest the cellulose.

Chapter 42: Circulation and Gas Exchange:
-Both open and closed circulatory systems have blood (a circulatory fluid). Vessels (tubes through which blood moves), and a heart (a structure that pumps the blood).
-In open circulatory systems, blood bathes the organs directly. The blood and lymph combined are called hemolymph, and a heart pumps hemolymph into cavities called sinuses.
-In closed circulatory systems, blood is contained within vessels and pumped around the body; the blood is separated from the interstitial fluid.
-Humans have a closed circulatory system called the cardiovascular system. The heart has atria (chambers that receive blood returning to the heart) and ventricles (chambers that pump blood out of the heart).
-The main types of blood vessels in humans are the arteries, veins, and capillaries. Arteries carry blood away from the heart and branch into smaller arterioles. Then capillaries network to form capillary beds. These capillary beds converge into venules, which converge into veins, which carry the blood back to the heart.
-Fluid flows into capillary bed at the upstream end near an arteiole and out of a capillary at the downstream near a venule.
-Velocity of blood flow is lowest in the capillaries.
-Here are the steps of double circulation in mammals:
1. The right ventricle pumps blood to the lungs through the pulmonary arteries.
2.The blood floes through capillary beds in the lungs and picks up oxygen and relases CO2.
3. The blood returns to the left atrium of the heart via pulmonary veins.
4. Then it continues to the left ventricle.
5. Then it leaves the heart via the aorta, which sends bloos to the arteries throught the body.
6. The blood enters the capillary beds in the neck, head, and arms.
7. The blood enters capillary beds in the abdomen and legs, giving up oxygen and picking up CO2 from cell respiration.
8. The capillaries form the venules, and the blood from the neck, head and arms travels back to the veins and back to the right atrium via the anterior vena cava.
9. Blood from the legs and trunk travels through the posterior vena cava back to the right atrium.

1. Which blood vessel is thicker?
a) arteries
b) veins
c) capillaries

2. Which type of blood vessels carries blood away from the heart?

a) veins
b) arteries
c) capillaries
d) all of the above

3. Which is the organ that pumps blood throughout the human body?

a) the lungs
b) the heart
c) the kidneys
d) blood vessels

1. a.
2. a *tip: to help you remember that just think AA arteries-away*
3. b. i think you should know that by now.

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