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Tissues and Membranes

Explore the structure and functions of epithelial tissues, including squamous, cuboidal, and columnar types. Learn about connective tissue characteristics and types, such as collagenous and elastic fibers. Enhance your knowledge of glandular epithelium and its secretory functions.

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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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