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  • Cells vary in size, shape, and function. <br /> Each specialized cell, such as the red blood cells and the nerve cell shown here, possesses some or all of the properties of the typical cell. <br />
  • This is a typical cell with all known cellular components. <br /> Not all cells have all of these components. Specialized cells—such as nerve cells, skin cells, and muscle cells—have some or all of the properties of the typical cell. <br />
  • The cell membrane is primarily composed of phospholipids, which are arranged in two layers, and protein. <br /> The protein molecules provide structural support for the membrane, act as binding sites for hormones, and poke holes or pores through the lipid membrane. <br /> The pores form channels in the membrane through which water and dissolved substances can flow. The cell membrane is semipermeable—only some substances can cross the membrane. <br />
  • The inside of the cell is divided into two compartments, the nucleus and the cytoplasm. <br /> The nucleus is the part that contains the genetic information and controls all protein synthesis. <br /> Most adult cells have one nucleus. Mature red blood cells do not have a nucleus. <br />
  • The cytoplasm is the other compartment of a cell. <br /> What is cytosol composed of? <br /> Cytosol is composed primarily water, electolytes, and nutrients. <br />
  • The mitochondria are tiny, slipper-shaped organelles that are the power plants of the cells. They produce most of the energy (ATP) in the body. <br /> Why do you think the number of mitochondria vary among cells? <br /> The number of mitochondria per cell varies because of the metabolic activity of the cell. The harder a cell works, the greater the number of mitochondria. <br />
  • There are two types of membranes in the network known as the ER, rough and smooth. <br />
  • The Golgi apparatus is a series of flat membrane sacs. <br /> Depending on the protein’s final destination, the Golgi finish the protein by adding or removing sugars (such as glucose). <br /> Once the proteins are complete, the Golgi wrap them in a bit of membrane; it is then called a secretory vesicle. The membrane-enclosed proteins move toward the cell membrane and are secreted from the cell. <br />
  • Lysosomes contain powerful enzymes that break down cellular waste; they do the intracellular “housecleaning.” They use powerful digestive enzymes to conduct phagocytosis. <br /> Movement produced by the cytoskeleton is especially evident in muscle cells. <br /> Centrioles come in pairs and contribute to cellular reproduction. <br />
  • Cilia use wavelike motions to move substances across the surface of the cell. The swishing motion of a flagellum enables the sperm to swim. <br /> Smoking destroys cilia and interferes with the trapping of dust and pollutants. <br />
  • This table reviews the cellular structures and functions just covered. <br /> If the nucleus is like the yolk of an egg, then the cytoplasm is the egg white. <br />
  • Which type of ER is concerned with the synthesis of lipids? <br /> The SER is primarily concerned with the synthesis of steroids and lipids. <br /> A mitochondrion has two membrane layers. Which one is involved in ATP production? <br /> The cristae. <br />
  • Which of these organelles are known as digestive organelles? <br /> Lysosomes are digestive organelles that break down intracellular waste and debris. <br /> The centrioles play a key role in what function of the cell? <br /> They play a key role in cellular reproduction. <br />
  • The ball rolling down the hill on its own illustrates a passive transport mechanism; no additional energy from ATP is required for it to take place. <br /> The ball being pushed uphill illustrates an active transport mechanism. This form of transport mechanism requires additional energy in the form of ATP. <br />
  • Passive and active transport mechanisms assist in the movement of water and dissolved substances across the cell membrane. <br /> These transport mechanisms also operate in other parts of the body. <br />
  • Diffusion is the most common transport mechanism. <br /> Figure A shows diffusion of the red dye tablet in a glass of water. The tablet dissolves and the dye moves from an area of high concentration to an area of low concentration. <br /> Figure B shows diffusion of a scent through the air. <br /> Equilibrium is the point at which no further net diffusion occurs. Even though some individual molecules might still move about, the balance is maintained. <br />
  • Diffusion is the mechanism that is responsible for moving oxygen into the blood and carbon dioxide out of the blood. <br />
  • Facilitated diffusion is illustrated by the boy carrying the glucose. He is moving downhill, but he is helping (facilitating) the process of diffusion. This increases the rate of diffusion. <br />
  • Osmosis is a special case of diffusion that happens through a selectively permeable (semipermeable) membrane. <br /> What is the function of a semipermeable membrane? <br /> A semipermeable—or selectively permeable—membrane allows the passage of some substances while restricting the passage of others. <br /> During osmosis, what diffuses? <br /> Water diffuses from an area where there is more water to an area where there is less water. The dissolved solute does not diffuse because the molecule is too big. <br />
  • When an RBC is placed in an isotonic solution, no net movement of water occurs. In the hypotonic solution, the water will diffuse into the cell and the RBC will burst, or undergo lysis. If the RBC is placed within a hypertonic solution, water will diffuse out of the RBC, causing it to shrink, or crenate. <br /> Why are most IV solutions isotonic? <br /> To avoid damage to red blood cells. <br />
  • The syringes shown in the slide are analogies illustrating passive transport mechanisms in the circulatory system. <br /> Syringe 1: Movement of blood through the vessels in response to pressure the heart generates. <br /> Syringe 2: More like movement across the capillary walls. <br /> The last illustration (C) shows both forward movement and movement across a membrane. <br />
  • Active transport mechanisms require an input of energy. They pump from an area of lower concentration to one of higher concentration. <br /> The only way to move additional amounts of potassium into a cell is to pump the potassium in. Most potassium is located inside the cell, so moving the K+ (potassium ion) from an area of lower concentration to an area of higher concentration requires a pump. <br />
  • When a particle is too large to move across the membrane by diffusion, the cell membrane surrounds the particle and takes it into the cell. <br /> Phagocytosis involves a solid particle, but pinocytosis involves a water droplet. Phagocytosis is “cellular eating, and pinocytosis is “cellular drinking.” <br />
  • Exocytosis moves substances out of the cells. This is the process that, among other things, helps export the proteins built by the RER and processed and packaged by the Golgi apparatus. <br /> This is the way most protein leaves the cell. <br />
  • Cell division, or cell reproduction, is important to the human body. Cells have a limited life span, so cellular division is necessary for bodily growth and repair. <br /> Some cells, such as skin cells, bone marrow cells, and the cells lining the digestive tract, reproduce rapidly. Other cells, such as some nerve cells, do not reproduce at all. <br />
  • During first gap phase, a cell carries on normal function and begins to make substances needed for cell division. During the S phase, the cell duplicates its chromosomes. The final preparatory phase, or second gap phase, includes the synthesis of enzymes and other proteins needed for mitosis, the M phase. <br /> Anticancer drugs affect cells during different phases and are classified accordingly. For example, methotrexate is S phasespecific because it affects the cell in its S phase. <br /> Some cells keep cycling and others go into a resting phase. Ask students to find G0 on the slide. <br />
  • In mitosis, pairs of identical chromosomes line up in the middle of the cell. Threadlike spindles then attach to the chromosomes and pull apart, splitting each pair of chromosomes into two equal sets. Mitosis ends with cytokinesis, during which the cell membrane pinches together to split the cytoplasm into two separate, identical cells. <br /> Fig. 3-14 <br />
  • Cell differentiation begins with an unspecialized cell, called a stem cell. The enzymes then switch on, and the cells become the specialized cells needed by the various tissues of the body. <br /> During mitosis, a single cell divides many times into identical cells. These cells then start to specialize, or differentiate, by the enzymes that are switched on during this change. <br />   <br />
  • Most cell growth is orderly and controlled, but disruptions can occur. <br /> Metaplasia is the formation of an abnormal cell type. Exposure to toxins can cause metaplasia. <br /> For example, the thick columnar cells that usually line the breathing passages can change into thin, scaly squamous cells in a person who smokes. <br /> These changes are reversible if the condition causing the metaplasia is removed (i.e., if the smoker quits). <br />
  • If metaplasia is caused by a carcinogen, then there is also danger that the genetic changes will lead to dysplasia and neoplasia. <br /> Necrosis, or cell death, can result from oxygen deprivation, poison, bacterial toxicity, radiation. <br /> Metastasis is the spread of cancer cells from the original tumor site. <br />

Chapter 003 Chapter 003 Presentation Transcript

  • The Human Body in Health and Illness, 4th edition Barbara Herlihy Chapter 3: Cells 1
  • Lesson 3-1 Objectives • Label a diagram of the main parts of a typical cell. • Identify the structure of the cell membrane. • Explain the role of the nucleus. • Describe the functions of the main organelles of the cell. Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 2
  • Cells Are Specialized • Cells are basic units of all living matter. • Cell structures reflect their specialized functions. Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 3 View slide
  • A Typical Cell Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 4 View slide
  • Cell Membrane • Cell membrane – Encases cell – Regulates what enters and leaves the cell – Semipermeable Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 5
  • Inside the Cell • Nucleus – Controls the workings of the entire cell – Is surrounded by double-layered nuclear membrane – Found inside the nucleus • Nucleoplasm: Gel-like substance • Nucleolus: Involved in synthesis of ribosomes • Chromatin: Threadlike structure that contains genes Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 6
  • Inside the Cell (cont’d.) • Cytoplasm: A gel-like substance found inside the cell but outside the nucleus • Composed of – Cytosol (gel-like) – Organelles (“little organs”) Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 7
  • Cytoplasmic Organelles • Mitochondria – Slipper-shaped power plants of cell – Two layers • Smooth outer layer • Folds (cristae) in inner layer Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 8
  • Cytoplasmic Organelles (cont’d.) • Ribosomes – Sites of protein synthesis – Fixed and free • Endoplasmic reticulum (ER) – Network of membranes in cytosol – Rough endoplasmic reticulum (RER): Fixed ribosomes on surface – Smooth endoplasmic reticulum (SER): No ribosomes; site of lipid and steroid synthesis Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 9
  • Cytoplasmic Organelles (cont’d.) • Golgi apparatus – Puts finishing touches on protein after synthesis on RER – Packages protein in Golgi membrane Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 10
  • Cytoplasmic Organelles (cont’d.) • Lysosomes – Break down waste for “housekeeping” within the cell • Cytoskeleton – Composed of microfilaments and microtubules – Provides for intracellular shape and support • Centrioles – Are rod-shaped structures – Help separate chromosomes during mitosis Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 11
  • • Cilia On the Cell Membrane – Short, hairlike projections – Wavelike motions move substances across cell’s surface • Flagella – Whiplike: thicker, longer, and fewer in number than cilia – Enable sperm to swim • Microvilli – Help move water across cell membrane Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 12
  • Cell Structure and Function Summary Cell Structure Function Cell membrane Contains cellular contents; regulates what enters and leaves the cell Surrounds and supports organelles; medium through which nutrients and waste move Contains genetic information; control center of the cell Cytosol Nucleus Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 13
  • Cell Structure and Function Summary (cont’d.) Cell Structure Function Endoplasmic reticulum (ER) Rough (RER) Smooth (SER) Mitochondria Golgi apparatus Transports material through the cytoplasm Contains the ribosomes, where proteins are synthesized Site of lipid and steroid synthesis Produce ATP Packages protein in membrane; puts finishing touches on protein Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 14
  • Cell Structure and Function Summary (cont’d.) Cell Structure Ribosomes Lysosomes Function Sites of protein synthesis Cytoskeleton “Housekeeping” within cell; conduct phagocytosis using powerful enzymes Provides for intracellular shape and support Centrioles Separate chromosomes during mitosis Cilia Create movement over cell surface Flagella Enables the sperm to swim Microvilli Water transport Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 15
  • Lesson 3-2 Objectives • Describe the active and passive movement of substances across a cell membrane. • Define tonicity and compare isotonic, hypotonic, and hypertonic solutions. • Describe the active and passive movement of substances across a cell membrane. • Describe the phases of the cell cycle. • Explain what is meant by cell differentiation. Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 16
  • Passive and Active Transport Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 17
  • Transport Mechanisms • Passive mechanisms – Diffusion – Facilitated diffusion – Osmosis – Filtration • Active mechanisms – Active transport pumps – Endocytosis – Exocytosis Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 18
  • Passive Transport: Diffusion • Movement of a substance from an area of higher concentration to one of lower concentration • Equilibrium: Point at which concentration is equal and no further net diffusion occurs Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 19
  • Passive Transport: Diffusion (cont’d.) Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 20
  • Passive Transport: Facilitated Diffusion • A helper molecule within the membrane assists with the movement of substances from higher to lower concentration. Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 21
  • Passive Transport: Osmosis • Movement of water (solvent) from area with more water to area with less water Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 22
  • Passive Transport: Osmosis (cont’d.) • Tonicity: Ability of a solution to affect the volume and pressure within a cell Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 23
  • Passive Transport: Filtration • Movement of water and dissolved substances from an area of higher pressure to an area of lower pressure • Water and dissolved substances are pushed. Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 24
  • Active Transport: Pumps • Active transport pumps – Move substance from area of lower concentration to area of higher concentration – Require input of energy (ATP) Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 25
  • Active Transport: Endocytosis • Ingestion of substances by the cell membrane – Phagocytosis – Pinocytosis Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 26
  • Active Transport: Exocytosis • Secretion of cellular products out of the cell Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 27
  • Cell Division • Types of cell reproduction (division) – Mitosis: Bodily growth and repair – Meiosis: Sex cells only • Cell cycle: The sequence of events that a cell goes through from one mitotic division to the next Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 28
  • Cell Cycle • Two phases of cell cycle – Interphase – Mitosis • Interphase – First gap phase (G1) – Phase (S) – Second gap phase (G2) Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 29
  • Cell Division (cont’d.) • Mitosis (M) – Four phases: Prophase, metaphase, anaphase, telophase – Chromosomes line up and split into two identical sets. – Ends with cytokinesis: Cell membrane pinches to create two identical cells Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 30
  • Cell Differentiation Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 31
  • Disorders of Cellular Growth • Atrophy – Decrease in size of cells; leads to a wasting away of tissues and organs • Dysplasia – Change in shape, size, organization; can become cancerous • Hyperplasia – Overgrowth or increase in number of cells; results in increase in size of tissues and organs Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 32
  • Disorders of Cellular Growth (cont’d.) • Metaplasia – Transformation of one cell type into another • Necrosis – Death of cells or groups of cells • Neoplasm – Abnormal new growth, also called a tumor – Malignant neoplasms (cancerous tumors) are invasive and tend to metastasize from original (primary) site to another (secondary) site. Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 33