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Introduction to Tissues, Organ Systems, and Homeostasis

Introduction to Tissues, Organ Systems, and Homeostasis. Chapter 4. Homeostasis. Stable operating conditions in the internal environment Brought about by coordinated activities of cells, tissues, organs, and organ systems. Tissue.

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Introduction to Tissues, Organ Systems, and Homeostasis

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  1. Introduction to Tissues, Organ Systems, and Homeostasis Chapter 4

  2. Homeostasis • Stable operating conditions in the internal environment • Brought about by coordinated activities of cells, tissues, organs, and organ systems

  3. Tissue • A group of cells and intercellular substances that interact in one or more tasks • Four types Epithelial tissue Muscle tissue Connective tissue Nervous tissue

  4. Organs • Group of tissues organized to perform a task or tasks • Heart is an organ that pumps blood through body • Heart consists of muscle tissue, nervous tissue, connective tissue, and epithelial tissue

  5. Organ Systems • Organs interact physically, chemically, or both to perform a common task • Circulatory system includes the heart, the arteries, and other vessels that transport blood through the body

  6. Epithelial Tissue • Lines the body’s surface, cavities, ducts, and tubes • One free surface faces a body fluid or the environment simple squamous epithelium basement membrane connective tissue

  7. Simple Epithelium • Consists of a single layer of cells • Lines body ducts, cavities, and tubes • Cell shapes: Squamous Cuboidal Columnar

  8. Stratified Epithelium • Two or more layers thick • Functions in protection, as in skin • Cells in the layers may be squamous, columnar, or cuboidal

  9. Glands • Secretory organs derived from epithelium • Exocrine glands have ducts or tubes • Endocrine glands are ductless

  10. Cell Junctions • Tight junctions prevent leaks • Gap junctions connect abutting cytoplasms • Adhering junctions cement cells together

  11. Connective Tissue • Most abundant tissue in the body • Cells are scattered in an extracellular matrix • Matrix is collagen and/or elastin fibers in a polysaccharide ground substance

  12. Soft Connective Tissues Loose connective tissue Dense, irregular connective tissue Dense, regular connective tissue

  13. Specialized Connective Tissues Cartilage Bone Adipose tissue

  14. Blood • Classified as a connective tissue because blood cells arise in bone • Serves as the body’s transport medium • Red cells, white cells, and platelets are dispersed in a fluid medium called plasma

  15. Muscle Tissue • Composed of cells that contract when stimulated • Helps move the body and specific body parts

  16. Three Types of Muscle • Skeletal muscle • Smooth muscle • Cardiac muscle

  17. Skeletal Muscle • Located in muscles that attach to bones • Long, cylindrical cells are striated • Cells are bundled closely together in parallel arrays

  18. Smooth Muscle • In walls of many internal organs and some blood vessels • Cells are not striped and taper at the ends

  19. Cardiac Muscle • Present only in the heart • Cells are striated and branching • Ends of cells are joined by communication junctions

  20. Nervous Tissue • Detects stimuli, integrates information, and relays commands for response • Consists of excitable neurons and supporting neuroglial cells

  21. Neurons • Excitable cells • When stimulated, an electrical impulse travels along the plasma membrane • Arrival of the impulse at the neuron endings triggers events that stimulate or inhibit adjacent neurons or other cells

  22. Neuroglia • Constitute more than half of the nervous tissue • Protect and support the neurons, both structurally and metabolically

  23. Replacement Tissues • Artificial skin • Bioengineered cartilage and bone • Organoapatites and coral to repair bone

  24. Stem Cells • Have the potential to develop into different kinds of mature cells • Embryonic cells most useful but use of embryos as source is controversial • Some adult tissues also may provide stem cells

  25. Membranes • Epithelial tissue membranes • Mucous membranes • Serous membranes • Cutaneous membrane • Connective tissue membranes • Synovial membranes

  26. Major Organ Systems • Integumentary • Muscular • Skeletal • Nervous • Endocrine • Lymphatic • Respiratory • Urinary • Circulatory • Reproductive

  27. Major Body Cavities • Cranial cavity • Spinal cavity • Thoracic cavity • Abdominal cavity • Pelvic cavity

  28. Planes of Symmetry Frontal plane (aqua) Transverse plane (yellow) Midsagittal plane (green)

  29. Primary Tissues • In vertebrate embryos, cells become arranged to form three primary tissues Ectoderm Mesoderm Endoderm • These give rise to all adult tissues

  30. Functions of Human Skin • Protects the body from injury, dehydration, UV radiation, and some pathogens • Helps control temperature • Receives some external stimuli • Produces vitamin D

  31. Structure of Human Skin • Part of body’s integument • Two layers • Outer epidermis • Inner dermis • Atop a layer of hypodermis

  32. Epidermis • Stratified epithelium • Grows from bottom upward • Most abundant cells are keratin-producing keratinocytes • Melanocytes produce the brown pigment melanin

  33. Dermis • Dense connective tissue with many elastin and collagen fibers • Includes blood vessels, lymph vessels, and receptor endings of sensory nerves

  34. Sweat Glands • Arise from epidermal cells • Composition of sweat • 99% water, with dissolved salts, trace of ammonia (waste product) • Controlled by sympathetic nerves

  35. Oil Glands • Also called sebaceous glands • Derived from epidermal cells • Secretions lubricate and soften hair and skin; also kill many surface bacteria • Acne occurs when bacteria infect oil-gland ducts

  36. Hair • Root is embedded in skin • Cells near the base of root divide, push cells above them upward • Hair follicles nourished by the dermis • Shaft of dead cells extends above the skin surface

  37. UV Damages Skin • UV light stimulates melanin production in skin; produces a tan • Tan is the body’s way of protecting itself against UV • Prolonged sun exposure causes elastin fibers to clump, skin to age prematurely, increases risk of cancer

  38. Body Fluids • The human body contains about 15 liters of fluid • Fluid outside of cells is extracellular fluid • Interstitial fluid lies between cells • Plasma is the fluid portion of the blood

  39. Fluid Balance • Changes in extracellular fluid cause changes in cells • The component parts of every animal work to maintain a stable fluid environment for living cells

  40. Homeostasis • Stable operating conditions in the internal environment STIMULUS (input into the system) RESPONSE (system’s output) RECEPTOR (e.g., free nerve ending in the skin) INTEGRATOR (such as the brain) EFFECTOR (a muscle or a gland) Response to the stimulus leads to change. Change is “fed back” to the receptor.

  41. Negative Feedback • Some activity alters a condition in the internal environment • Alteration triggers a response • Response reverses the altered condition

  42. Positive Feedback • Some activity alters the internal environment • The alteration triggers a response • The response intensifies the change in the internal condition

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