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25 Lecture Ppt

  1. 1. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chapter 25 Animal Organization and Homeostasis
  2. 2. The Structure of Tissues Suits Their Function 25-
  3. 3. 25.1 Levels of biological organization are evident in animals <ul><li>An animal’s body is composed of specialized cells that perform particular functions </li></ul><ul><ul><li>Body contains trillions of cells, of which there are approximately 100 different types </li></ul></ul><ul><ul><li>Tissue - group of similar cells performing a similar function </li></ul></ul><ul><ul><li>Organ contains different types of tissues arranged in a certain fashion </li></ul></ul><ul><ul><li>Several organs comprise an organ system </li></ul></ul><ul><ul><li>Organs of the system work together to perform necessary functions for the organism </li></ul></ul>25-
  4. 4. Figure 25.1 Levels of biological organization 25-
  5. 5. Four Types of Tissues Are Common in the Animal Body 25-
  6. 6. 25.2 Epithelial tissue covers organs and lines body cavities <ul><li>Epithelial tissue ( epithelium ) - forms external and internal linings of many organs and covers the surface of the body </li></ul><ul><ul><li>In order for a substance to enter or exit the body at the digestive tract, the lungs, or the urinary tract, it must cross an epithelial tissue </li></ul></ul><ul><li>Epithelial cells are connected to one another by three junctions </li></ul><ul><ul><li>Tight junctions </li></ul></ul><ul><ul><li>Adhesion junctions </li></ul></ul><ul><ul><li>Gap junctions </li></ul></ul><ul><li>Basement membrane - two thin layers of proteins that anchor the epithelium to underlying connective tissue </li></ul>25-
  7. 7. Figure 25.2 Types of epithelial tissue in vertebrates 25-
  8. 8. 25.3 Connective tissue connects and supports other tissues <ul><li>Connective tissue is the most abundant and widely distributed tissue in vertebrates </li></ul><ul><ul><li>Connective tissue - involved in binding organs together and providing support and protection </li></ul></ul><ul><ul><li>Matrix - noncellular material that separates connective tissue cells </li></ul></ul>25-
  9. 9. Loose Fibrous and Related Connective Tissues <ul><li>Loose fibrous connective tissue - Occurs beneath an epithelium and connects it to other tissues within an organ </li></ul><ul><ul><ul><li>Cells are called fibroblasts because they produce a matrix that contains fibers </li></ul></ul></ul><ul><li>Adipose tissue - Type of loose connective tissue in which the fibroblasts enlarge and store fat, and there is limited matrix </li></ul><ul><ul><ul><li>Dense fibrous connective tissue contains more collagen fibers, and they are packed closely together </li></ul></ul></ul><ul><ul><ul><li>Found in tendons , which connect muscles to bones, and in ligaments , which connect bones to other bones at joints </li></ul></ul></ul><ul><li>Cartilage - Cells lie in small chambers called lacunae , separated by a matrix that is solid yet flexible </li></ul><ul><ul><li>Hyaline cartilage - most common type of cartilage, contains only very fine collagen fibers </li></ul></ul><ul><li>Bone - most rigid connective tissue consisting of an extremely hard matrix of inorganic salts, notably calcium salts, deposited around collagen fibers </li></ul>25-
  10. 10. Figure 25.3A Types of connective tissue in vertebrates 25-
  11. 11. Blood <ul><li>Blood - composed of several types of cells suspended in a liquid matrix called plasma </li></ul><ul><ul><li>Unlike other types of connective tissue in that the matrix (i.e., plasma) is not made by cells </li></ul></ul><ul><li>Transports nutrients and oxygen to cells and removes their wastes </li></ul><ul><ul><li>Helps distribute heat and plays a role in fluid, ion, and pH balance </li></ul></ul><ul><li>Contains two types of cells </li></ul><ul><ul><li>Red blood cells - small, biconcave, disk-shaped without nuclei </li></ul></ul><ul><ul><ul><li>Hemoglobin makes the cells red and, in turn, makes the blood red </li></ul></ul></ul><ul><ul><ul><li>Hemoglobin combines with oxygen to transport oxygen </li></ul></ul></ul><ul><ul><li>White blood cells - usually larger than red blood cells, have a nucleus, and, without staining, would appear translucent </li></ul></ul><ul><ul><ul><li>White blood cells fight infection either by engulfing infectious pathogens, or producing antibodies, molecules that combine with foreign substances to inactivate them </li></ul></ul></ul><ul><li>Platelets - not complete cells; rather, they are fragments of giant cells present only in bone marrow </li></ul>25-
  12. 12. Figure 25.3B Composition of blood, a liquid tissue 25-
  13. 13. 25.4 Muscular tissue is contractile and moves body parts <ul><li>Muscular tissue - called contractile tissue because it contains contractile protein filaments, called actin and myosin filaments </li></ul><ul><ul><li>Skeletal muscle ( voluntary muscle ) - attached by tendons to the bones of the skeleton, and when it contracts, the bones move </li></ul></ul><ul><ul><ul><li>Fibers have alternating light and dark bands that give them a striated appearance </li></ul></ul></ul><ul><ul><li>Cardiac muscle - found only in the walls of heart and contraction pumps blood and accounts for heartbeat </li></ul></ul><ul><ul><ul><li>Cardiac muscle cells are separate and individual, but they are bound end to end at intercalated disks </li></ul></ul></ul><ul><ul><li>Smooth muscle - the cells lack striations </li></ul></ul><ul><ul><ul><li>Called involuntary because it is not under voluntary control </li></ul></ul></ul><ul><ul><ul><li>Also called visceral muscle because it is found in the walls of viscera and blood vessels </li></ul></ul></ul>25-
  14. 14. Figure 25.4 Types of muscular tissue 25-
  15. 15. 25.5 Nervous tissue communicates with and regulates the functions of the body’s organs <ul><li>Nervous tissue coordinates body parts and allows an animal to respond to the environment </li></ul><ul><li>The nervous system depends on </li></ul><ul><ul><li>Sensory input </li></ul></ul><ul><ul><li>Integration of data </li></ul></ul><ul><ul><li>Motor output to carry out its functions </li></ul></ul><ul><li>Neuron - nerve cell that has three parts </li></ul><ul><ul><li>Dendrite - extension that conducts signals toward cell body </li></ul></ul><ul><ul><li>Cell body - contains major concentration of the cytoplasm and nucleus of the neuron </li></ul></ul><ul><ul><li>Axon - extension that conducts nerve impulses </li></ul></ul><ul><ul><ul><li>Nerves contain only the axons of neurons </li></ul></ul></ul><ul><li>Neuroglia - cells that outnumber neurons as much as 50 to 1, and take up more than half the volume of the brain </li></ul><ul><ul><li>Supports and nourish neurons, but research is currently being conducted to determine how much they directly contribute to brain function </li></ul></ul><ul><ul><li>Also form a plasma-like solution called cerebrospinal fluid , which supports and nourishes the brain and spinal cord </li></ul></ul>25-
  16. 16. Figure 25.5 Parts of a neuron and types of neuroglia 25-
  17. 17. APPLYING THE CONCEPTS—HOW BIOLOGY IMPACTS OUR LIVES 25.6 Will nerve regeneration reverse a spinal cord injury? <ul><li>In 1995, Christopher Reeve was thrown from his horse, crushing his spinal cord </li></ul><ul><ul><li>Reeve’s improvement was the result of exercise </li></ul></ul><ul><ul><li>It is possible that Reeve’s advances were the result of improved strength and bone density, which led to stronger nerve signals </li></ul></ul><ul><li>In humans, damaged axons within the central nervous system (CNS) do not regenerate and the result is permanent loss of nervous function </li></ul><ul><ul><li>Reeve was convinced that stem cell therapy would one day allow him to be off his ventilator and functioning normally </li></ul></ul>25-
  18. 18. Organs, Composed of Tissues, Work Together in Organ Systems 25-
  19. 19. 25.7 Each organ has a specific structure and function <ul><li>Structure and function of an organ is dependent on the tissues it contains </li></ul><ul><ul><li>Skin - an organ in vertebrates is enhanced by a thickened and keratinized epidermis </li></ul></ul><ul><li>Regions of the Skin </li></ul><ul><ul><li>Epidermis - made of stratified squamous epithelium </li></ul></ul><ul><ul><ul><li>New cells derived from stem cells in the germinal layer become flattened and hardened as pushed to the surface </li></ul></ul></ul><ul><ul><li>Dermis - region of dense fibrous connective tissue beneath the epidermis </li></ul></ul><ul><ul><ul><li>With age and exposure to the sun, the number of collagen and elastic fibers in dermis decrease, resulting in wrinkles </li></ul></ul></ul><ul><li>Subcutaneous layer beneath the dermis is not a part of the skin </li></ul><ul><ul><li>Loose connective tissue and adipose issue, which stores fat </li></ul></ul>25-
  20. 20. Photomicrograph of skin 25-
  21. 21. Figure 25.7 Human skin anatomy 25-
  22. 22. All Organ Systems Contribute to Homeostasis in Animals 25-
  23. 23. 25.8 Several organs work together to carry out the functions of an organ system <ul><li>All of the body’s systems are involved in maintaining homeostasis , the stability of the body’s internal environment </li></ul><ul><li>Control </li></ul><ul><ul><li>Nervous system (brain, spinal cord, and associated nerves) allow us to respond to both external and internal stimuli </li></ul></ul><ul><ul><li>Endocrine system - consists of hormonal glands, which secrete chemicals that serve as messengers between body parts </li></ul></ul><ul><li>Sensory Input and Motor Output </li></ul><ul><ul><li>Integumentary system - consists of skin and its accessory structures such as sensory receptors in the skin, and organs such as the eyes and ears that are sensitive to external stimuli </li></ul></ul><ul><ul><li>Skeletal system and muscular system enable the body and its parts to move as a result of nerve stimulation </li></ul></ul>25-
  24. 24. Figure 25.8A The control systems 25-
  25. 25. Figure 25.8B Sensory input and motor output 25-
  26. 26. Transport <ul><li>Cardiovascular system - consists of heart and blood vessels that carry blood through the body </li></ul><ul><ul><li>Heart propels blood into two circuits </li></ul></ul><ul><ul><ul><li>One takes blood to the lungs, and the other takes blood to the body proper </li></ul></ul></ul><ul><ul><li>Cells surrounded by liquid called tissue fluid </li></ul></ul><ul><ul><ul><li>Blood transports nutrients and oxygen to tissue fluid for cells, and removes waste molecules excreted by cells </li></ul></ul></ul><ul><li>Lymphatic system - consists of lymphatic vessels that carry lymph, and lymphatic organs, including lymph nodes </li></ul><ul><ul><li>Lymphatic vessels absorb fat from the digestive system and collect excess tissue fluid, which is returned to the blood in the cardiovascular system </li></ul></ul><ul><ul><li>Certain blood cells in the lymph and blood are part of an immune system , which protects the body from disease </li></ul></ul>25-
  27. 27. Figure 25.8C The body’s transport systems 25-
  28. 28. Maintenance <ul><li>Digestive system - consists of the organs along the digestive tract </li></ul><ul><ul><li>Also includes associated organs, such as teeth, salivary glands, liver, and pancreas </li></ul></ul><ul><ul><ul><li>digestive system receives food and digests it into nutrient molecules that enter the blood </li></ul></ul></ul><ul><li>Respiratory system - consists of the lungs and tubes that take air to and from lungs </li></ul><ul><ul><li>Body has a way to store energy but has no way to store oxygen </li></ul></ul><ul><ul><li>Therefore, respiratory system brings oxygen into body and takes carbon dioxide out of body via the lungs </li></ul></ul><ul><li>Urinary system - contains the kidneys and the urinary bladder along with tubes that transport urine </li></ul><ul><ul><li>Rids blood of wastes and also helps regulate the fluid level and chemical content of the blood </li></ul></ul>25-
  29. 29. Figure 25.8D The body’s maintenance systems 25-
  30. 30. Reproduction <ul><li>Reproductive system - involves different organs in the male and female </li></ul><ul><ul><li>Male reproductive system </li></ul></ul><ul><ul><ul><li>Testes, other glands, and various ducts that conduct semen to and through the penis </li></ul></ul></ul><ul><ul><ul><ul><li>The testes produce sex cells called sperm </li></ul></ul></ul></ul><ul><ul><li>Female reproductive system </li></ul></ul><ul><ul><ul><li>Ovaries, oviducts, uterus, vagina, and external genitals </li></ul></ul></ul><ul><ul><ul><ul><li>The ovaries produce sex cells called eggs </li></ul></ul></ul></ul><ul><li>When a sperm fertilizes an egg, an offspring begins to develop </li></ul>25-
  31. 31. Figure 25.8E The reproductive system 25-
  32. 32. APPLYING THE CONCEPTS—HOW SCIENCE PROGRESSES 25.9 Organs for transplant may come from various sources <ul><li>Xenotransplantation - use of animal organs in transplant patients </li></ul><ul><ul><li>Ordinarily, the human body would violently reject transplanted pig organs </li></ul></ul><ul><ul><li>Genetic engineering has allowed pig valves to be successfully used in human hearts </li></ul></ul><ul><li>It is possible to make replacement organs in lab </li></ul><ul><ul><li>Example: two skin products have now been approved for use in humans </li></ul></ul><ul><li>Tissue engineers have also created cellular implants that produce a useful product encapsulated within a narrow plastic tube or a capsule the size of a dime or quarter </li></ul><ul><ul><li>Researchers have been able to produce a working urinary bladder in the laboratory </li></ul></ul>25-
  33. 33. <ul><li>Figure 25.9A Burn victim who Figure 25.9B Lab-grown </li></ul><ul><li>received artificial skin as a bladder ready to serve as a </li></ul><ul><li>transplant transplant </li></ul>25-
  34. 34. 25.10 Homeostasis is the constancy of the internal environment <ul><li>Your body’s internal environment is the environment of the cells </li></ul><ul><ul><li>Cells live in a liquid environment called tissue fluid, which is constantly renewed by exchanges with the blood </li></ul></ul><ul><li>Body systems contribute to maintaining homeostasis </li></ul><ul><ul><li>Cardiovascular system conducts blood to and away from capillaries, where exchange occurs </li></ul></ul><ul><ul><li>Digestive system takes in and digests food, providing nutrient molecules that enter the blood to replace those that are constantly being used </li></ul></ul><ul><ul><li>Nervous system and the endocrine system regulate the other systems of the body and work together to control body systems so that homeostasis is maintained </li></ul></ul>25-
  35. 35. Figure 25.10 Process of achieving constancy in the internal environment (blood and tissue fluid) 25-
  36. 36. 25.11 Homeostasis is achieved through negative feedback mechanisms <ul><li>Negative feedback </li></ul><ul><ul><li>Sensor detects a change in the internal environment (a stimulus) </li></ul></ul><ul><ul><li>The control center initiates an effect that brings conditions back to normal </li></ul></ul><ul><li>Complex examples </li></ul><ul><ul><li>In humans, the thermostat for body temperature is located in the hypothalamus </li></ul></ul><ul><ul><ul><li>When core body temperature becomes higher than normal, the control center directs (via nerve impulses) the blood vessels of the skin to dilate </li></ul></ul></ul><ul><ul><ul><ul><li>More blood is then able to flow near surface of the body, where heat can be lost to the environment </li></ul></ul></ul></ul><ul><ul><ul><li>When core body temperature falls below normal, the control center directs the blood vessels of the skin to constrict, conserving heat </li></ul></ul></ul>25-
  37. 37. Figure 25.11A Model of negative feedback 25-
  38. 38. Figure 25.11B Regulation of body temperature by negative feedback 25-
  39. 39. Connecting the Concepts: Chapter 25 <ul><li>Structure suits function - The function of an organ is reflected in its structure </li></ul><ul><ul><li>Function of heart is to pump blood, and therefore it contains chambers for holding blood and has thick, muscular walls for pumping blood </li></ul></ul><ul><li>Homeostasis - The relative constancy of the internal environment </li></ul><ul><ul><li>In complex animals, internal environment is blood and tissue fluid </li></ul></ul><ul><ul><li>Nervous and endocrine systems act together to regulate the actions of organs so that homeostasis is maintained </li></ul></ul><ul><ul><li>Receptors gather information from external and internal environments and convert it to a form that can be processed by nervous system </li></ul></ul><ul><ul><li>Movement brought about by the skeletal and muscular systems may be required to achieve homeostasis </li></ul></ul>25-