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Tissues. Ch 4. Tissues. Major Tissue Types. Tissues are groups of cells with a common function. Epithelial Tissue Connective Tissue Muscle Tissue Nervous Tissue. Tissues. Germ Layers. All tissue types are derived from 3 primary germ layers. Endoderm Mesoderm Ectoderm. Germ layers.
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Tissues Ch 4
Tissues Major Tissue Types Tissues are groups of cells with a common function. • Epithelial Tissue • Connective Tissue • Muscle Tissue • Nervous Tissue
Tissues Germ Layers All tissue types are derived from 3 primary germ layers • Endoderm • Mesoderm • Ectoderm
Fates of Primary Germ Layers • Endoderm- internal lining of the gut and respiratory pathways, liver, pancreas • Mesoderm- notochord (in chordates), dermis, blood vessels, heart, bones, cartilage, muscle • Ectoderm- hair, nails, epidermis, brain, nerves
Cell Junctions Contact points between the plasma membrane of tissue cells. • Tight Junction • fluid tight seal • prevents fluid from leaving a cavity • Anchoring Junction (adherens, desmosome & hemidesmosome) • tissues that stretch, ex. Heart muscle • Gap Junction • passage of chemical & electrical signals
Cell Junctions Gap Junction Tight Junction Adherens Hemidesmosome Desmosome
Epithelial Tissues • Epithelia comes in 2 forms: • Glandular epithelia • Membranous epithelia • Functions: • Protection • Absorption • Filtration • Excretion • Secretion • Sensory reception
Exocrine Gland ducted glands • Multicellular exocrine gland: most have supportive connective tissue, secretory unit, blood supply, nerves • Merocrine- pancreas, sweat glands, salivary • Holocrine- sebaceous • Apocrine- sweat glands, mammary glands Merocrine gland Holocrine gland
Exocrine Gland Unicellular exocrine gland:single cells scattered in an epithelial sheet amid cells w/other functions Goblet cells
Multicellular Exocrine Gland Sebaceous Sweat glands Liver Lg intestine Gastric Cowper’s Mammary Acinar of pancreas
Exocrine vs Endocrine Gland Secretes product directly directly in blood Secretes product through duct
Epithelial Tissues • Simple Squamous Epithelium • Simple Cuboidal Epithelium • Simple Columnar Epithelium • Stratified Epithelium • Pseudostratified Columnar Epithelium • Transitional Epithelium
Simple Squamous Epithelium Function: gas exchange in lungs Location: lines blood vessels, lymph vessels and various membranes within the thorax and abdomen
Simple Squamous Cells Frog skin
Simple Cuboidal Epithelium Function: secretion and absorption Location: kidney tubules
Simple Cuboidal Epithelium Mammalian kidney
Simple Columnar Epithelium Function: protection, secretion and absorption (associated w/goblet cells-exocrine) Location: lines uterus and digestive tract
Simple Columnar Epithelium 1. Smooth muscle (long. layer) 2. Smooth muscle (circ. layer) 3. Simple columnar epithelium 4. Goblet cell 5. Lumen of the intestine Cross section of small intestine
Stratified Squamous Epithelium Function: protects underlying cells from harmful env. effects Location: covers skin, lines mouth and throat, vagina, and anal canal
Stratified Squamous Epithelium 1. Stratified squamous epithelium 2. Lumen of the esophagus 3. Connective tissue Cross section of esophagus
cornified layer of dead cells stratified squamous epithelium Epidermis of the Skin
goblet cell Pseudostratified Columnar Epithelium Function: secretion and propulsion of mucus Location: lines respiratory and reproductive system
Stratified Columnar Epithelium Function: protection and secretion Location: rare in body, small amount in male urethra and in large ducts of some glands
Transitional Epithelium Function: stretches Location: lines ureters, bladder and part of urethra
Connective Tissues • Loose Connective Tissue • Dense Connective Tissue • Adipose Tissue • Cartilage • Bone • Blood
Connective Tissues • Functions: • Connects body parts • Protection • Insulation • Transport substances • Common characteristics: • All originate from mesenchyme • Well vascularized • Extracellular matrix • Three main elements: • Ground substance • Fibers • Cells
Connective Tissues • Ground Substance: • Water • Polysaccharide • Protein
Connective Tissues • Fibers: • Reticular • Elastic • Collagen
Connective Tissues • Cell Types: • Fibroblast • Chondroblast • Osteoblasts • Macrophages • Plasma Cells • Mast Cells • Adipocytes • White Blood Cells
Loose Connective Tissue(areolar) 1. Collagen fiber 2. Elastic fiber • Subcutaneous layer underlying tissues & organs
Adipose Tissue • Stores triglycerides • Good insulator • Supports & protects organs
Dense Connective Tissue • Forms tendons & ligaments
Dense Regular Connective Tissue Cross section of tendon
Dense Irregular Connective Tissue Dermis of skin • In fascia and periosteum of bone
Hyaline Cartilage Costal cartilage between ribs
elastic fibers Elastic Cartilage chondrocytes in lacunae
collagen fibers chondrocyte in lacuna Fibrocartilage Invertebral discs, pubic symphysis, disks of knees
Bone spongy bone Compact bone
osteocytes in lacunae canaliculi in matrix central canal Compact Bone
Blood leukocytes erythrocytes
Muscle Tissue • Skeletal Muscle Tissue • Smooth Muscle Tissue • Cardiac Muscle Tissue