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Understanding Different Types of Tissues in the Human Body

Explore the various tissue types in the body, from epithelial to connective, muscle, and nervous tissues, each with unique functions. Learn about characteristics, structures, and examples of each tissue type for a better understanding of tissue organization and repair processes.

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Understanding Different Types of Tissues in the Human Body

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  1. Cell Types & Tissues Chapter 3

  2. What are Tissues? • Tissues are groups of cells that have similar function • There are 4 main tissue types: • Epithelial Tissue • Connective Tissue • Muscle Tissue • Nervous Tissue

  3. Epithelial Tissue • Fit Closely together to form continuous sheets • Cells are bound together via tight junctions and proteins called desmosomes • Always have 1 free surface: the apical surface, exposed to the body exterior or cavity of an organ • Lower surface rests on the basement membrane – structureless material secreted by the cells

  4. Epithelial Tissue • Avascular – having no blood supply • These tissues rely on diffusion of materials through the capillaries that lie in the connective tissue • Easily regenerated

  5. Epithelial Tissue • Organized by shape and the number of layers • Shape • Squamous – Flat, Tile-like • Cuboidal – Cube Shape • Columnar – Column Shape • Layers • Simple – one layer • Stratified – multiple layers • Pseudostratified – columnar only, one layer of cells with variable heights • Transitional – vary due to stretching – cuboidal to columnar basal membrane

  6. Simple Squamous Epithelia

  7. Stratified Squamous Connective Tissue

  8. Stratified Squamous Epithelia

  9. Stratified Squamous Epithelia

  10. Simple Cuboidal Epithelia

  11. Simple Columnar Epithelia

  12. Pseudostratified Columnar

  13. Glandular Tissue • Secrete various products • 2 different types of glands • Endocrine – ductless, have lost their connection to the surface • Secretions diffuse into nearby capillaries • Example: Thyroid • Exocrine – Retain their ducts and empty secretion on epithelial surface • Examples: Sweat and Oil glands, Liver, and Pancreas

  14. Connective Tissue • Most are highly vascularized • Tendons & Ligaments = Poor Blood Supply • Cartilage = Avascular • These 3 take a LONG time to heal because of little/no blood • Made of living cells surrounded by a non-living Extracellular Matrix (ECM) • ECM Gives the ability • to bear weight • to form a soft tissue around organs • to withstand stretching and other abuses

  15. Connective Tissue • Types: • Bone – Osseous Tissue – Protects body organs • Cartilage – flexible - 3 types • Hyaline – lots of collagen, ribs, larynx, joints, & fetal skeleton • Fibrocartilage – highly compressible, intervertebral disks • Elastic – flexible, outer ear & nose

  16. Bone

  17. Hyaline Cartilage Stratified Squamous Epithelia

  18. Hyaline Cartilage

  19. Fibrocartilage

  20. Elastic Cartilage

  21. Connective Tissue • Loose – Fewer fibers, softer • Areolar – widely distributed, protective wrapping of organs • Adipose – lots of fat cells, insulation and cushioning • Reticular – LOTS of fibers, forms the stroma of lymph organs to support free blood cells – need special stain to see! • Dense – Lots of Fibers, very organized

  22. Areolar

  23. Adipose

  24. Reticular Connective Tissue

  25. Dense Regular Connective

  26. Connective Tissue • BLOOD – made of cells surrounded by a nonliving ECM • Contains fibers that remain invisible until a vessel is broken • Then these fibers come together to form a clot

  27. Blood

  28. Blood

  29. Muscle Tissue • Specialized to contract, or shorten • Cells are elongated to provide better contraction • Individual Cells are called fibers • There are 3 types: • Skeletal • Cardiac • Smooth

  30. Skeletal Muscle Tissue • Fibers are organized into sheets that form the organs, Skeletal Muscles • Attached to the Skeleton • Voluntary Muscles – can be consciously controlled • Cells are • Long • Cylindrical • Multinucleate • Striated – Striped

  31. Skeletal Muscle

  32. Skeletal Muscle

  33. Skeletal Muscle

  34. Cardiac Muscle Tissue • Found only in the heart • Cells are • Uninucleate • Branching • Striated • Branches meet at junctions called intercalated disks • Allow ions to move freely from cell to cell – creates electrical impulse • Involuntary – not under conscious control

  35. Cardiac Muscle

  36. Smooth Muscle Tissue • Found in the walls of hollow organs and vessels • Contraction causes the cavity of an organ to either constrict or dilate • Contracts more slowly than the other 2 types of muscle • Ex: Peristalsis – wavelike motion that keeps food moving through the digestive system • Cells are • Uninucleate • Spindle-shaped • Not Striated

  37. Smooth Muscle Connective Tissue

  38. Nervous Tissue • Receive and conduct electrochemical impulses • Cells have long extensions which allow a single neuron to reach multiple sites • Along with numerous supporting cells, they make up the nervous system organs – spinal cord, brain, and nerves

  39. Nervous Tissue

  40. Nervous Tissue

  41. Tissue Repair • 2 major processes • Regeneration • Replacement of cells with the same kind of cells • Fibrosis • Replacement of cells with Dense Connective Tissue, or scar tissue • Depends on type of cells damaged and what type of injury took place

  42. Tissue Repair • Damaged tissue brings a series of events into motion: • Capillaries become permeable • Allows clotting proteins to enter damaged area to stop blood loss and ‘wall off’ the damaged area • This prevents bacteria or other harmful materials from entering

  43. Tissue Repair • Granulation tissue forms • Delicate pink tissue, full of tiny capillaries that bleed freely when damaged (picking a scab) • Contains phagocytes to dispose of the clot and collagen making fibroblasts that synthesize scar tissue to permanently fix the gap

  44. Tissue Repair • Surface epithelium regenerates • Newly made epithelial cells grow just under the scab, which will fall off • Leaves new surface over scar tissue. • Scar may be visible, as a white line, or invisible depending on the wound severity

  45. Which Tissues Repair Themselves? • Regenerate Well • Epithelial • Fibrous Connective & Bone • Smooth Muscle • Regenerate Poorly (surgical) • Skeletal Muscle • Cartilage • No Regeneration (all scar) • Nervous Tissue • Cardiac Muscle

  46. Cancer • 50% of Americans will have cancer at one point in their life • 20% of Americans will die from cancer • A group of >100 diseases • All involve uncontrolled proliferation of cells • The process begins with one cell that is mutated and begins to grow uncontrollably • Each daughter cell produced will carry the same trait for uncontrolled cell division

  47. Cancer • These cells will form a tumor: • in situ – within the original tissue • invasive – within nearby tissue • Many in situ tumors are benign, not harmful, and can be surgically removed. • All invasive tumors and some in situ tumors are considered malignant, dangerous. • Malignant tumors are likely to metastasize, spread to other parts of the body and establish new tumors

  48. Cancer Growth Model

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