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Chapter 4. The Tissue Level Of Organization. Epithelial Tissue (90). HISTOLOGY: The study of tissues EPITHELIAL TISSUE includes: Epithelia Glands Characteristics: Closely-bound cells A free surface Attachment to a basement membrane No blood vessels Continual loss and regeneration.
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Chapter 4 The Tissue Level Of Organization
Epithelial Tissue (90) • HISTOLOGY: The study of tissues • EPITHELIAL TISSUE includes: • Epithelia • Glands • Characteristics: • Closely-bound cells • A free surface • Attachment to a basement membrane • No blood vessels • Continual loss and regeneration
Functions of Epithelia • Provide physical protection • Impacts, scrapes, restricts water loss, bacteria • Control permeability • Relative impermeability to protein permeability • Provide sensation • receptors • Produce specialized secretions • Glands; exocrine (e.g. sweat) and endocrine (e.g. hormones)
Intracellular Connections • Cell membranesareheldtogether by: • Specialized transmembrane proteins called CELL ADHESION MOLECULES (CAMs) • Thin layer of intercellular cement (protein-polysaccharide mixture) • 3 Common intracellularconnections: • Tight junctions • Gap junctions • Desmosomes
The Epithelial Surface • A free (Apical) surface • Surface exposed to: • outer environment • Internal chamber or passageway • So this surface can be internal or external
The Basement Membrane Lies between the epithelium and the connecting tissue
Epithelial Renewal and Repair Done via unspecialized cells called STEM CELLS
Classifying Epithelia • REFER TO PAGE 93, Table 4 – 1 • Simple • Secretion or absorption occurs • Digestive and urinary tracts, lungs • Stratified • Skin, mouth, anus • Squamous, Cuboidal, or Columnar • Good diagrams on page 95, Figure 4-4
Simple Squamous Squama – plate or scale (scale as in a snake, not a mass) Look like fried eggs laid side-by-side Do yourself a favor and DO NOT google this word unless you like to vomit. I.E. some things cannot be unseen… :/ E.g. lining of the heart
Simple Cuboidal And by “cube” we don’t mean square boxes, we mean hexagonboxes. E.g. the kidney
Simple Columnar Slender & taller and, therefore, the more attractive epithelium E.g. intestinal lining
Glandular Epithelia • Exocrine Secretions • Endocrine Secretions • Modes of (crine) secretion: • Mero (vesicles) • Apo (parts) • Holo (whole)
Connective Tissues (99) • 3 components: • Specialized cells • Protein fibers • Ground substance • Functions: • Support and protection • Transportation • Storage • defense
Classifying Connective Tissues Connective tissue proper Fluid connective tissues Supporting connective tissues
Connective Tissue Proper Many types of cells and fibers within a matrix containing a soupy ground substance Fatty tissue, tendons, ligaments Loose Dense
Fluid Connective Tissues Cells suspended in a matrix of watery ground substance containing dissolved proteins Blood Lymph
Supporting Connective Tissues Less diverse cell population than connective tissue proper Cartilage Bone
MEMBRANES (106) • This word has multiple meanings, even in Anatomy and physiology • Cellular level – lipid bilayers • Tissue level – barriers • Epithelia & connective tissues combine to form membranes that protect other structures and tissues. There are four: • Mucous • Serous • Cutaneous • Synovial
Why so serous? • Mucous membranes (mucosae) myou-KOH-see • Based with a loose connective tissue called the lamina propria • Serous (sealed, internal subdivisions of the ventral body cavity) • Pleura, peritoneum, pericardium • Parietal (inner) • Visceral (outer) • Cutaneous • Skin • Synovial • Articulations (joints) • Synovial fluid
Muscle Tissue (107) My favorite teeshue. I work hahrd. You will need pay-pah teeshue if you wook out wit me.
Neural Tissue • Also, nervous or nerve tissue • 2 types of cells: • Neurons • Thought processes • Neuroglia • Support neurons
Neuron • Longest cells in the body (up to 1m) • Do not normally divide • Therefore, have limited repair capability • Has 3 main parts • Cell body • Dendrites • Axon (or nerve fibers)
Basic Neuron Anatomy Cell body is sometimes called the cellsoma or just soma. Recall that soma is Greek for body. Not Shown: Synaptic Terminals
Tissue Injuries and Repair (110) • Restoring Homeostasis involves 2 steps: • Inflammation • Regeneration
Inflammation • From physical injury or pathogens • Stimuli stimulate connective tissue cells called mast cells (pg. 100) • Mast cells release histamine and heparin • This causes local blood vessels to dilate (enlarge) • That causes redness, swelling, and warmth (to the touch) • All the conditions produce pain • The increased blood flow is to allow more oxygen and nutrients to help aid in the repair process.
Regeneration Fibroblasts produce a dense network of collagen fibers (scar/fibrous tissue) Over time the scar gradually becomes more normal-looking if it doesn’t disappear completely. Regenerative capabilities just depend on the structure and make-up of that tissue. Permanent replacement of the tissue is called fibrosis. That is one of the ways you can tell if someone had a heart attack.