why are the cells of spongy layer packed so tightly together
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Be Part of Ask A Biologist If you take a close look at epithelial cells using a microscope, you will see them tightly packed together. This helps make a protective barrier for our bodies. There are also some special door-like connections between each epithelial cell called gap junctions. The gap junctions are where the cells exchange nutrients.
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Cell Junctions Tight junctions often occur in a belt completely encircling the cell. In a sheet of such cells, material cannot pass from one side of the sheet to the other by squeezing between cells. Instead, it must go through a cell, and hence the cell can regulate its passage.
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Structure of Leaves: The Epidermis, Palisade and Spongy Layers The cuticle and upper epidermis provide protection for the plant. Below that is the palisade layer, which is the location of photosynthesis within the leaf. Below the palisade layer is the spongy layer, which contains cells that are more spread out, allowing for air pockets. Within the spongy layer are vascular bundles that contain xylem and phloem, allowing for the transport of products of photosynthesis. Together, the palisade and spongy layers are known as the mesophyll. The bottom of the leaf is protected by the lower epidermis.
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Structure of Bone Tissue Compact Bone. Compact bone consists of closely packed osteons or haversian systems. The osteon consists of a central canal called the osteonic (haversian) canal, which is surrounded by concentric rings (lamellae) of matrix. Between the rings of matrix, the bone cells (osteocytes) are located in spaces called lacunae.tructure of Bone Tissue. There are two types of bone tissue: compact and spongy. The names imply that the two types differ in density, or how tightly the tissue is packed together.
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- Spongy bone is lighter and less dense than Compact bone. It consists of plates and bars of bone adjacent to small, irregular cavities that contain red bone marrow. Compact bon … e consists of closely packed osteons or Haversian systems.t is lighter than compact bone.    Compact bone is generally on the outer edges of bone. it is  composed of multiple osteon units that are bunched closely together  like stacked logs and, thus, is good at bearing weight in the long  direction. Spongy bone is generally on the inside of compact bone.
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Leaf Structure The inside of the leaf looks like this: Spongy mesophyll cells are not packed so tightly together, which allows carbon dioxide and oxygen to reach the palisade cells where they are needed in photosynthesis.Spongy mesophyll cells and guard cells (see below) also get some photosynthetic action.his tissue is called the mesophyll, meaning middle leaf, and comes in two flavors: the palisade mesophyll (sometimes called palisade parenchyma) and the spongy mesophyll. Most photosynthesis takes place in the palisade mesophyll, which is conveniently located at the top of the leaf just under the epidermis.
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Junctions Between Cells Simplified Tight junctions seal adjacent cells together to regulate the passage of water and other molecules between epithelial cells. For example, in the small intestine tight junctions allow the body the regulate what and how fast molecules enter the blood stream.
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Ch. 6 Describe the structure of spongy bone. Spongy bone appears porous, has less bone matrix and more space than compact bone. Trabeculae are interconnecting rods or plates in spongy bone, which bear weight and help bones resist bending and twisting. Through their canaliculi.
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The skeletal SYstem of porifera Agelas tubulata (Brown Tube Sponge). The skeleton of the sponge is composed of tiny needle-like splinters called spicules, a mesh of protein called spongin, and sometimes a combination of both. Many sponges can only be identified by microscopic examination of the skeleton because they are so small.he mesohyl functions as a endoskeleton in the majority of sponges. They do not contain any steletal system within their bodies but they do contain a exoskeleton. Their bodies have no definite structure but their body shapes adapt to the flow of water around them.
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Cell Junctions Imagine a largely waterproof zipper connecting the sides of two different jackets. That zipper is like a tight junction (TJ), also called an occluding junction. A TJ creates a small zone that occludes the extracellular space (the space between cells). This is why tight junctions are also called zonula occludens.
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Histology Photomicrographs Spongy bone is a network of irregularly-shaped sheets and spikes of bone (trabeculae). The trabeculae are only a few cell layers thick. The spaces between the trabeculae contain red or yellow marrow, depending on a person's age and on which bone it is.The marrow in these images is red marrow.he trabeculae are only a few cell layers thick. The spaces between the trabeculae contain red or yellow marrow, depending on a person's age and on which bone it is. The marrow in these images is red marrow.
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Skin The outer layer of our skin, the epidermis, is subdivided into two layers: a thin surface layer of dead cells, called the stratum corneum, and a deeper layer of living cells.ndeed, we might call the stratum corneum “miracle wrap.”. In thin skin, the dead cells are flattened like thin pancakes and are stacked on top of one another in precise columns (Figures 1 and 2). Each cell is tightly attached to its neighbors on top and bottom by over a hundred little “spot welds” called desmosomes.
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- Place theses steps in the correct order: (1) bony matrix fuses to form trabeculae. (2) clusters of osteoblasts forma center of ossification taht secretes organic extracellular matrix. (3) spongy bone is replaced by compact bone on the bone's surface.
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plant tissue & leaf structure why are the epidermis layers of the leaf coated in a waxy cuticle? the cuticle is the protective layer on top of the leaf & keeps the water in the leaf why are the cells of the palisades layer packed so tightly together? the light has to pass through one of them where it can be trapped why are the cells of the spongy layer acted so loosely together?
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- The cell membrane is mostly composed of phospholipid molecules. Each of these has a polar head and a non-polar tail part. The polar bits are attracted to water (hydrophilic) ,… and the non-polar parts repel water (hydrophobic). In the membrane, they form a double layer - like a sandwich - the polar heads stick out, and the tails form the middle, like the filling inside the sandwich.
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Junctions Between Cells Tight Junctions Epithelia are sheets of cells that provide the interface between masses of cells and a cavity or space (a lumen). The portion of the cell exposed to the lumen is called its apical surface. The rest of the cell (i.e., its sides and base) make up the basolateral surface.
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- Water moves through the canals, into the chambers, and out through the central canal and osculum. THE SKELETON. The skeleton of a sea sponge is made up of tiny needlelike splinters called spicules. Spicules consist of a mesh of protein called spongin.Many sea sponges can only be identified by the microscopic examination of the skeleton.Because of this, indentification from photographs can become very difficult. sea sponge's body primarily consists of spicules and spongin. Spicules are needle shaped fiberlike structures that act as the sponge's skeleton. Spongin is a protein that helps provide body support. In some instances the spongin will combine with the spicules to provied support, in other times the spongin works alone.
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The Life of a Sponge The skeleton of the sponge is composed of tiny needle-like splinters called spicules, a mesh of protein called spongin, or a combination of both. Many sponges can only be identified by microscopic examination of the skeleton, which makes certain identification from photographs difficult.he collar cells have a sticky, funnel shaped collar and a hairlike whip, called a flagellum. The collar cells serve two purposes. First, they beat their flagella back and forth to force water through the sponge. The water brings in nutrients and oxygen, while it carries out waste and carbon dioxide.
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What does a spongy cell do in plants and photosynthesis? What do spongy mesophyll cells do? Spongy mesophyll cells are usually ball or irregularly shaped and contain a limited number o chloroplasts. It is found below the palisade layer. The large spaced between each …cell in the mesophyll allow for the exchange of gases which is incredibly important to a plants survival.
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Cell Membrane: Functions, Role & Structure The phospholipids of a cell membrane are arranged in a double layer called the lipid bilayer. The hydrophilic phosphate heads are always arranged so that they are near water. Watery fluids are found both inside a cell (intracellular fluid) and outside a cell (extracellular fluid).hospholipids make up the basic structure of a cell membrane. A single phospholipid molecule has two different ends: a head and a tail. The head end contains a phosphate group and is hydrophilic. This means that it likes or is attracted to water molecules.
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- Tight junction. Tight junctions, also known as occluding junctions or zonulae occludentes (singular, zonula occludens), are the closely associated areas of two cells whose membranes join together forming a barrier virtually impermeable to fluid. It is a type of junctional complex present only in vertebrates.
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Structure of Bone Tissue Structure of Bone Tissue. There are two types of bone tissue: compact and spongy. The names imply that the two types differ in density, or how tightly the tissue is packed together.There are three types of cells that contribute to bone homeostasis.Osteoblasts are bone-forming cell, osteoclasts resorb or break down bone, and osteocytes are mature bone cells.tructure of Bone Tissue. There are two types of bone tissue: compact and spongy. The names imply that the two types differ in density, or how tightly the tissue is packed together.
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Spongy mesophyll cells - what do they exactly do? Adhesion is a property of water that allows water to stick to the cell walls of the spongy mesophyll because of opposite charges. The effect of adhesion is similar to how soap doesn't drip after several seconds of rubbing your hands together.
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Cell Junctions Photo by: RAJCREATIONZS. Cell junctions can be divided into two types: those that link cells together, also called intercellular junctions (tight, gap, adherens, and desmosomal junctions), and those that link cells to the extracellular matrix (focal contacts/adhesion plaques and hemidesmosomes).ight Junctions. The tight junction (also referred to as a zonula occludens) is a site where the membranes of two cells come very close together. In fact, the outer leaflets of the membranes of the contacting cells appear to be fused.
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You are made up of trillions and trillions of cells, and each one is separated Phospholipids make up the basic structure of a cell membrane. A single phospholipid molecule has two different ends: a head and a tail. The head end contains a phosphate group and is hydrophilic.This means that it likes or is attracted to water molecules.his ensures that the cells will be able to get rid of wastes and take up important nutrients and gases. The plasma membrane is a fluid mosaic. This means that it is flexible and made up of many different types of molecules. Phospholipids form the basic structure of a cell membrane, called the lipid bilayer.
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Cell Membrane Function and Structure 1 Cholesterol molecules are selectively dispersed between membrane phospholipids. 2  This helps to keep cell membranes from becoming stiff by preventing phospholipids from being too closely packed together. 3  Cholesterol is not found in the membranes of plant cells.