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Histology by Mind Map: Histology


2. Epithelial Tissue

2.1. Stratified

2.1.1. Squamous Epithelium location Nonkeratinized type forms the moist linings of the esophagus, mouth, and vagina; keratinized variety forms the epidermis of the skin, a dry membrane. structure Multiple layers, basal cells are cuboidal or columnar and metabolically active; surface cells are flattened (squamous); in the keratinized type, the surface cells are full of keratin and dead; basal cells are active in mitosis and produce the cells of the more superficial layers function Provide physical protection against abrasion, pathogens, and chemical attacks.

2.1.2. Cuboidal epithelium location Largest ducts of sweat glands, mammary glands, and salivary glands. structure Multiple layers, generally two layers of cube-like cells. function Protection, secretion, absorption

2.1.3. Columnar epithelium location Rare in the body; small amounts in male urethra and in large ducts of some glands. structure Multiple layers, basal cells usually cuboidal; superficial cells elongated and columnar. function Protection; secretion

2.1.4. Transitional epithelium location Lines the ureters, urinary bladder, and part of the urethra; renal pelvis. structure Resembles both stratified Squamous and stratified cuboidal; basal cells cuboidal or columnar: surface cells dome shaped or squamous-like, depending on degree of organ stretch. function Stretches readily and permits distension of urinary organ by contained urine

2.2. Simple

2.2.1. Squamous Epithelium location kidney glomeruli, air sacs of lungs; lining of heart; blood vessels; lining of ventral body cavity structure Single layer, disc-shaped central nuclei and sparse cytoplasm, thin, flat function Reduces friction; controls vessel permeability, performs absorption and secretion.

2.2.2. Cuboidal epithelium location Glands; ducts; portions of kidney tubules, thyroid gland, ovary surface structure Single layer, cube-like cells with large, spherical central nuclei. function Limited protection, secretion, absorption

2.2.3. Columnar epithelium location Nonciliated type lines most of the digestive tract (stomach to anal canal), gallbladder, and excretory ducts of some glands; ciliated variety lines small bronchi, uterine tubes, and some regions of the uterus. structure Single layer, tall cells with round to oval nuclei; some cells bear cilia; layer may contain mucus-secreting unicellular glands (goblet cells). function Protection, secretion of mucus, enzymes, and other substances ciliated type propels mucus (or reproductive cells) by ciliary action, absorption.

2.2.4. Pseudostratified columnar location Lining of nasal cavity, trachea, and bronchi; nonciliated type in male's sperm-carrying ducts and ducts of large glands; ciliated variety lines the trachea, most of the upper respiratory tract. structure Single layer of cells of differing heights, some not reaching the free surface; nuclei seen at different levels; may contain mucus-secreting cells and bear cilia. function Protection, secretion, particularly of mucus; propulsion of mucus by ciliary action.

3. Nervous Tissue

3.1. location

3.1.1. Brain, spinal cord, and nerves

3.2. structure

3.2.1. Neurons are branching cells; cell processes that may be quite long extend from the nucleus-containing cell body; also contributing to nervous tissue are nonirritable supporting cells (not illustrated)

3.3. function

3.3.1. Transmit electrical signals from sensory receptors and to effectors (muscles and glands) which control their activity.

4. Muscle Tissue

4.1. Skeletal muscle

4.1.1. location In skeletal muscles attached to bones or occasionally to skin.

4.1.2. structure Long, cylindrical, multinucleate cells; obvious striations

4.1.3. function Voluntary movement; locomotion; manipulation of the environment; facial expression; voluntary control

4.2. Cardiac muscle

4.2.1. location The walls of the heart.

4.2.2. structure Branching, striated, generally uninucleate cells that interdigitate at specialized junctions (intercalated discs)

4.2.3. function As it contracts, it propels blood into the circulation; involuntary control.

4.3. Smooth muscle

4.3.1. location Mostly in the walls of hollow organs.

4.3.2. structure Spindle-shaped cells with central nuclei; no striations; cells arranged closely to form sheets.

4.3.3. function Propels substances or objects (foodstuffs, urine, a baby) along internal passageways; involuntary control.

5. Connective Tissue

5.1. Loose connective tissue

5.1.1. Areolar location Widely distributed under epithelia of body, e.g., forms lamina propria of mucous membranes; packages organs; surrounds capillaries. structure Gel-like matrix with all three fiber types; cells: fibroblasts, macrophages, mast cells, and some white blood cells. function Wraps and cushions organs; its macrophages phagocytize bacteria; plays important role in inflammation; holds and conveys tissue fluid.

5.1.2. Adipose location Deep to the skin, especially at sides, buttocks, breasts; padding around eyeballs and kidneys. structure Matrix as in areolar, but very sparse: closely packed adipocytes, or fat cells, have nucleus pushed to the side by large fat droplet function Provides padding and cushions shocks; insulates (reduces heat loss); stores energy reserves

5.1.3. Reticular location Liver, Kidney, spleen, lymph nodes, and bone marrow structure Network of reticular fibers in a typical loose ground substance; reticular cells lie on the network function Fibers form a soft internal skeleton (stroma) that supports other cell types, including white blood cells, mast cells, and macrophages.

5.2. Dense connective tissue

5.2.1. Dense regular location Between skeletal muscles and skeletal (tendons and aponeuroses); between bones or stabilizing positions of internal organs(ligaments); covering skeletal muscles; deep fasciae. structure Primarily parallel collagen fibers a few elastic fibers; major cell type is the fibroblast. function Provides firm attachment; conducts pull of muscles; reduces friction between muscles; stabilizes relative positions of bones

5.2.2. Dense irregular location Fibrous capsules of organs and of joints; dermis of the skin; submucosa of digestive tract. structure Primarily irregularly arranged collagen fibers; some elastic fibers; major cell type is the fibroblast. function Able to withstand tension exerted in many directions; provides structural strength; helps prevent overexpansion of organs such as the urinary bladder

5.2.3. Elastic tissue location Walls of large arteries; within certain ligaments associated with the vertebral column; within the walls of the bronchial tubes. structure Dense regular connective tissue containing a high proportion of elastic fibers. function Allows recoil of tissue following stretching; maintains pulsatile flow of blood through arteries; aids passive recoil of lungs following inspiration.

5.3. Cartilage

5.3.1. Fibrocartilage location Intervertebral discs; pubic symphysis; discs of knee joint. strucure Matrix similar to but less firm than that in hyaline cartilage; thick collagen fibers predominate. function Tensile strength with the ability to absorb compressive shock.

5.3.2. Elastic cartilage location Supports the external ear (pinna); epiglottis. structure Similar to hyaline cartilage, but more elastic fibers in matrix function Maintains the shape of a structure while allowing great flexibility.

5.3.3. Hyaline location Forms most of the embryonic skeleton; covers the ends of long bones in joint cavities; forms costal cartilages of the ribs; cartilages of the nose, trachea, and larynx strucure Amorphous but firm matrix; collagen fibers form an imperceptible network; chondroblasts produce the matrix and when mature (chondrocytes) lie in lacunae. function Supports and reinforces; has resilient cushioning properties; resists compressive stress.

5.4. Bone/ Osseous tissue

5.4.1. location Bone

5.4.2. structure Hard, calcified matrix containing many collagen fibers; osteocytes lie in lacunae. Very well vascularized.

5.4.3. function Bone supports and protects (by enclosing); provides levers for the muscles to act on; stores calcium and other minerals and fat; marrow inside bones is the site for blood cell formation (hematopoiesis)

5.5. Blood

5.5.1. location Heart and blood vessels

5.5.2. structure Pale pink discs (erythrocytes), no nuclei, platelets, leukocytes are larger.

5.5.3. function Transport nutrients gases, waste, chemicals, heat, immunity, clotting, growth factor.