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Tissues and Membranes

Tissues and Membranes. Anatomy chapter 5. Body Tissues. A tissue is a group of cells that have similar structures and that function together as a unit. Histology – the microscopic study of tissues. There are 4 main tissue types in the body: Epithelial Muscle Connective Nervous.

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Tissues and Membranes

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  1. Tissues and Membranes Anatomy chapter 5

  2. Body Tissues • A tissue is a group of cells that have similar structures and that function together as a unit. • Histology – the microscopic study of tissues. • There are 4 main tissue types in the body: Epithelial Muscle Connective Nervous

  3. Tissue types

  4. Epithelial tissue

  5. Epithelial Tissue • Widespread throughout the body • Cover body surfaces • Line body cavities • Major tissue in glands • It always has a free surface – exposed to the outside or to open space internally • Jobs include protection, secretion, absorption, filtration, diffusion, and sensory reception

  6. Epithelial Tissue types

  7. Epithelial tissue • Tightly packed cells – very little intercellular matrix (the substance between cells) • Cells are attached to underlying tissue by the basement membrane, which is nonliving. • The basement membrane is a mixture of carbohydrates and proteins.

  8. Basement membrane The epithelial cells above receive their nutrients by diffusion from the blood vessels in the underlying tissues.

  9. Epithelial tissue • Are avascular – which means they have no blood supply directly. • Reproduce quickly (divide readily) • Are classified according to cell shape and number of layers in the tissue.

  10. Epithelial types Squamous cells are flat; the nuclei are broad and thin. Cuboidal – cubelike, the nuclei are spherical and centrally located. Columnar – are tall and narrow, nuclei are usually near the base

  11. Simple squamous epithelium • A single layer of thin, flat cells that fit closely together. • Alveoli in lungs • Capillary walls • Tissue is damaged easily.

  12. Simple squamous

  13. Simple Cuboidal Epithelium • A single layer of cube shaped cells. • Linings of many glands • Lining of kidney tubules • Absorption and secretion

  14. Simple Cuboidal

  15. Simple Columnar Epithelium • Single layer of cells that are taller than they are wide. • Lining the stomach and intestines, also lines the uterus • Secretes digestive enzymes, absorbs nutrients

  16. Simple columnar

  17. Simple columnar • Where absorption is necessary, these cells may have microvilli. • Goblet cells secrete mucus. • Cilia may be present

  18. Pseudostratified Columnar Epithelium • Appears to have multiple layers, but it really does not. • All cells attached to basement membrane. • Commonly have cilia • Usually in respiratory and male reproductive tract.

  19. Pseudostratifed Columnar

  20. Stratified Squamous Epithelium • The most common type of layered epithelium. • Many layers of cells. • Cuboidal at the basement membrane, become thinner near the surface.

  21. Stratified Squamous

  22. Stratified Squamous • Cells at the basement membrane undergo mitosis. • The cells die as they are pushed further from the basement membrane. • Outer layer of skin • As skin cells age, they accumulate keratin (a protein) and then harden and die.

  23. Stratified Cuboidal Epithelium • Two or three layers of cuboidal cells that form a lining of the lumen. • More protection than 1 layer. • Lines sweat, salivary and mammary glands, also the pancreas

  24. Stratified Columnar Epithelium • Several layers of cells. • Superficial layer are columnar, basal layers are cuboidal. • Found in the pharynx, also in the male urethra.

  25. Transitional Epithelium • A specialized type of tissue with several layers, but can be stretched in response to tension. • The lining of the bladder is an example.

  26. Transitional epithelium

  27. Glandular epithelium • Consists of cells that are specialized to produce and secrete substances. • Lies deep (underneath) epithelium that cover and line parts of the body. • Exocrine glands secrete their products onto a free surface via a duct.

  28. Types of glandular epithelium • Simple tubular – the ducts have no branches. • The gland and duct merge with no change in diameter.

  29. Types of glandular epithelium • Compound acinar • Has branches (compound) • Has sacs (acinar) • This type is also called alveolar

  30. Gland classified by mode of secretion • Merocrine glands – use exocytosis, no cytoplasm is lost. Example: salivary glands • Apocrine glands – Product accumulates in an area of the gland, then is pinched off – a small portion of the cell is lost. Example: sweat glands • Holocrine – the entire cell ruptures, releasing products. Example: Oil (sebaceous) glands

  31. Connective tissue

  32. Connective tissue • Binds structures together • Form a framework and support for organs and the body. • Store fat • Transport substances • Protect against disease and repair tissue damage.

  33. Connective tissue • Cells can reproduce, but not as quickly as epithelial tissue. • Three types of fibers embedded in intercellular matrix – collagenous fibers, elastic fibers and reticular fibers. • Many cell types in connective tissue. Most common are mast cells, macrophages, and fibroblasts

  34. Connective tissue cells • Fibroblasts – Most common. Large cells secrete proteins into the extracellular matrix. • Macrophages – Originate as white blood cells and carry on phagocytosis. Can move about • Mast Cells – Large cells usually near blood vessels. They release heparin and histamine.

  35. Fibers • Collagenous fibers – thick threads of the protein collagen. Grouped in bundles. Flexible but only slightly elastic. Important parts of ligaments and tendons. • Elastic – composed of the protein elastin. Weaker than collagenous, but stretch easily. Vocal cords. • Reticular – Very thin collagenous fibers. Highly branched and form a supporting network in organs like the spleen

  36. Types of connective tissue • Loose connective tissue • Adipose tissue • Elastic connective tissue • Dense fibrous connective tissue • Cartilage • Bone • Blood

  37. Loose connective tissue

  38. Loose connective tissue • Also called areolar CT • Packing material in the body • Attaches skin to underlying tissue, fills spaces between muscles.

  39. Adipose tissue • Better known as fat • Cells can take up fat and release it at a later date. • Acts as a cushion for the body, insulator for heat.

  40. Reticular connective tissue

  41. Dense Fibrous Connective Tissue • Closely packed parallel bundles of collagenous fibers. • Make up tendons and ligaments

  42. Elastic Connective Tissue • Closely packed elastic fibers. • Yields easily to pulling force. • Vocal cords and vertebral ligaments

  43. Cartilage • Has an abundant matrix – solid, yet flexible • Cartilage cells are called chondrocytes • Heals slowly – no direct blood supply • Protects underlying tissues, supports structures, and is a framework 3 types: hyaline, fibrocartilage, and elastic

  44. Hyaline cartilage Hyaline: most common type Found at the end of long bones Most of the fetal skeleton is made of this before it is replaced by bone

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