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Bio II Exam III
Circulation and Gas Exchange
| Question | Answer |
|---|---|
| Why do multicellular organisms need a circulatory system? | Cells need nutrients and removal of wastes and for transport of O2 and CO2. Diffusion is only effective at millimeter distances. |
| How does circulation occur in invertebrates? | It occurs in their gastrovascular cavities. In |
| How does circulation occur in Cnidaria? | Cnidaria the body cavity is two cells thick. Digestion and distribution occurs in the gut where inside cells have direct access and then nutrients diffuse to the outer layer. |
| How does circulation occur in Planaria and most flatworm? | Extreme gut branching. |
| What two kinds of circulatory system exist? | Open and closed. |
| What are components common in both types of system? | Blood, blood vessels, and pumps that use metabolic energy to create blood pressure. |
| What organisms have an open circulatory system? | Arthropods and most mollusks. |
| Describe the blood in an open system. | Blood and interstitial fluid (hemolymph) are the same. Heart(s) pump the hemolymph through the sinuses. |
| What are sinuses? | Spaces surrounding organs. |
| What is an insects heart? | A dorsal tub that contracts to move hemolymph. Relaxing causes the hemolymph to be drawn to the heart. Body movemets can also cause circulation. |
| What organisms have a closed system? | Earthworms, cephalopods, and vertebrates. |
| What are key features of a closed system? | Blood is kept in vessels and is not the same as interstitial fluids. |
| What are the advantages of an open system? | A lower pressure is kept, it requires less energy in general, and can support the species during molting and soft bodied mollusks. |
| What are the advantages of a closed system? | It is more efficient, larger crustaceans have more vessels, and blood movement to different areas can be controlled. |
| Describe the general vertebrate circulatory system. | They have a cardiovascular system, have one or two atria that receive incoming blood, one or two ventricles that pump outgoing blood, arteries, veins, and capillaries. |
| Describe arteries. | They carry blood to the body, branch into arterioles, and arterioles carry blood to the capillaries. |
| Describe capillaries. | They are microscopic vessels with very thin walls. Capillary beds infiltrate the tissues and allow gas and molecule exchange. |
| What are venules? | Venules are the ends of capillaries that converge into veins. |
| What do veins do? | Veins return the blood to the heart. The hepatic portal vein goes to the liver and the hepatic vein goes from the liver to the heart. |
| Describe a fish heart. | It has one atrium and one ventricle. |
| Describe gill circulation in fish. | Blood goes from ventricle to arteries to gills where blood obtains oxygen and disposes of carbon dioxide. |
| Describe an amphibian heart. | There are two atria and one ventricle. |
| What two systems do ventricles pump blood in amphibians? | Pulmocutaneus circuit and systemic circuit. |
| What occurs in the pulmocutaneus circuit in amphibians? | Blood goes to lung and skin capillaries where gas exchange occurs returning blood travels to the left atrium. |
| What occurs in the systemic circuit in amphibians? | This is where most of the blood gets pumped, it goes through the left systemic aorta and returns from the systemic circuit into the right atrium. |
| What occurs in the single ventricle in amphibians? | Oxygenated and deoxygenated blood mixes. |
| What is an advantage of this double circulation in amphibians? | This provides an extra boost for blood after traveling through the pulocutaneus circuit. |
| Describe the circulatory system in reptiles (but not birds). | They have double circulation and a pulmonary and systemic circuit. |
| Describe a reptiles heart. | It is three chambered, but ventricles are separates by a septum (crocodiles have a complete separation). |
| How many arteries lead from the heart to the systemic circuit in reptiles? | 2, the extra can divert blood from the pulmonary circuit to the systemic. |
| Why is diverting blood between circuits beneficial? | A species can control where the blood goes and this aids in thermoregulation and diving. |
| How can a reptiles heart change? | A crocodile's heart can become a fully functioning three chambered heart during diving. Some lizard heart become fully functioning 4 chambered hearts during pumping. |
| Describe the circulatory system in mammals and birds. | They have four chambered hearts with a convergent system. |
| Describe the function of the left and right chambers of a mammalian or bird heart. | The left chambers receive and pump oxygenated blood. The right receives and pumps deoxygenated blood. This creates a greater amount of pressure. |
| Why do endotherms have larger hearts and higher blood pressure? | Higher metabolism requires more oxygen and nutrients and the removal of more metabolic waste and CO2. |
| Describe how a mammalian heart generally works? | There are 4 chambers, relaxation fills vent., atr. have thinner walls and are collection points, contraction of at. tops off vent., contractions of vent. sends blood to circuits (left is stronger- systemic than right-pulmonary). |
| What two actions make up the cardiac cycle? | The systole (contraction) and diastole (relations). |
| What determines cardiac output? | The heart rate and stroke volume. |
| How many valves does the mammalian heart have? What do they do? | There are 4, they force blood into arteries and prevent back flow. |
| What happen when a heart stops beating? | Brain cells begin to die in minutes. |
| What is the sinoatrial node? | It is the pacemaker that sets the heart rate and allows cardiac muscle cells to be wired together. |
| How does the sinoatrial node work? | A signal in the node causes the atrium to contract, the contraction sends a signal to the atrioventricular node which causes the ventricles to contract. The electrical impulse travels through the blood and tissues. |
| What influences the SA node? | One set of nerves slows the node, another set speeds the node, the hormone epinephrine increases heart rate, and temp. |
Created by:
MichaelaMH
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