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22 Cards in this Set
- Front
- Back
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Why do multicellular animals need transport systems (3 reasons) |
Size- cells inside a large organism are further from its surface Large SA:V ratio- each gram of tissue has a smaller area of body surface for exchange High level of metabolic activity- cells need good supplies of nutrients and oxygen to supply the energy for movement and aerobic respiration. Some animals also need to keep themselves warm, which requires more energy |
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Describe the route blood takes in a single circulatory system |
Heart—>gills—>body—>heart |
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Route blood takes in a double circulatory system |
Heart—>body—>heart—>lungs—>heart Blood—>lungs= pulmonary circulation Blood—>body= systemic circulation |
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Advantage of double circulation |
Heart can increase blood pressure after passing through lungs, so blood flows to body quicker Systemic circulation can carry blood at a higher pressure than the pulmonary circulation
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Describe an open circulatory system |
Blood not always held in blood vessels Blood circulates body cavity so tissue and cells bathed in it |
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What is hydrostatic pressure |
The pressure that a fluid exerts when pushing against the sides of a vessel or container |
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Formation of tissue fluid |
Blood flowing into an organ or tissue contained in capillaries Arterial end of capillary, blood at relatively high hydrostatic pressure, pushes blood fluid out capillaries through tiny gaps between the cells In the wall Fluid that leaves consist of plasma with dissolved nutrients and oxygen. This is the tissue fluid |
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Function of tissue fluid |
Surrounds body cells, so exchange of gases and nutrients can occur across plasma membranes |
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Why do RBCs, WBCs, platelets and plasma proteins stay in the blood |
Too large to be pushed out gaps |
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What happens at the venous end of the capillary |
Blood pressure lower here, allows some tissue fluid to return to capillary with CO2 and other waste Some tissue fluid directed into lymph system |
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Function of lymph system and the name and composition of the fluid here |
Drains excess tissue fluid out tissues and returns it to blood system in vein in chest Fluid now called lymph Similar composition to tissue fluid but contains more lymphocytes (produced in lymph nodes- make up immune system) |
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What is oncotic pressure |
Pressure created by osmotic effects of solutes |
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How does oncotic pressure influence the movement of fluids |
Blood and tissue fluid have negative oncotic pressure so they both pull water back into themselves However the hydrostatic pressure is much higher at arteriole end resulting in fluid moving out capillaries here and moving in at venous end |
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Describe the open circulatory system in insects |
Contains a heart-like organ, a long muscular tube which lies under the upper surface of the body Blood enters heart through pores called ostia Heart pumps blood towards head by peristalsis Near head, blood pours out into body cavity Circulation can continue when insect is at rest but still affected by body movements |
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Describe a closed circulatory system |
Blood stays entirely in blood vessels Tissue fluid bathed tissues and cells |
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What is the single layer of cells that all blood vessels are lined with |
Endothelium |
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Describe structure of arteries and what the 3 layers consist of |
Thick wall Relatively small lumen to maintain high pressure Inner layer- elastic tissue, allows wall to stretch and recoil to maintain blood pressure Middle layer- thick layer of smooth muscle Outer layer- relatively thick layer of collagen and elastic tissue, provides strength to withstand pressure |
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Structure of arterioles and function |
Distribute blood from artery to capillaries Contain layer of smooth muscle- contraction will construct diameter of arteriole, reduces rate of blood flow |
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Structure of capillaries |
Single layer of flattened endothelial cells Leaky walls- allow blood plasma and dissolved substances to leave blood Lumen very narrow- one cell thick, increases resistance and reduces rate of flow, reduces diffusion path |
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Structure and function of venules |
Collect blood from capillaries and lead into veins Thin layers of muscle and elastic tissue outside endothelium Thin outer layer of collagen |
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Structure of veins |
Relatively large lumen Thinner layers of collagen, smooth muscle and elastic tissue compared to artery wall Contain valves to prevent backflow |
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What does blood plasma contain |
Dissolved substances- oxygen, CO2, minerals, glucose, amino acids, hormones and plasma proteins Blood cells- RBCs, WBCs, platelets |
