Chp 4: Tissues Flashcards
TIssue: definition
Groups of cells, similar in structure and perform a common/related function
4 Major Types of Tissues
epithelial, connective, muscle, nervous
3 Primary Germ Layers, from which germ layers are each of the major tissue types derived?
Superficial to deep: ectoderm, mesoderm, endoderm
Epithelium: all 3
Nervous: ectoderm
Muscle and Connective: mostly mesoderm
How do we classify epithelial tissues?
By number of layers (simple vs stratified)
Those that can’t be placed in other categories: transitional epithelium and pseudostratified epithelium
Simple Epithelia
Single layer: Absorption, secretion, filtration
Simple Squamous epithelium
flattened laterally, spare cytoplasm
thin and permeable, important for diffusion and filtration (kidney glomeruli, air sacs of lungs, lymphatic vessels- endothelium and serous membranes- mesothelium)
Simple cuboidal epithelium
single layer, as tall as wide
secretion and absorption, located in kidney tubules, ducts and secretory portions of small glands, ovary surface
Simple columnar epithelium
tall, closely packed cells
Absorption and secretion
Lines digestive tract, secretes mucus; ciliated variety lines bronchi, uterine tubes, and regions of uterus
Pseudostratified columnar epithelium
All cells rest on basement membrane, only tallest reach surface of epithelium
secretes mucus, absorbs
ciliated variety lines respiratory tract, nonciliated type in sperm ducts/ducts of large glands
Stratified squamous epithelium
thick membrane composed of several cell layers
Protects underlying tissues from abrasion
Nonkeratinized tpye forms moist linings of esophagus, mouth, and vagina
Keratinized variety forms epidermis of skin
Transitional Epithelium
Resembles both stratified squamous and stratified cuboidal; cells of basal layer are cuboidal or columnar, cells of apical (surface) layer vary in appearance depending on degree of organ distension (stretching)
Stretches readily, permits stored urine to distend urinary organ. Located in ureters, bladder, part of urethra
Gland
One or more cells that make and secrete a particular product
Exocrine Glands
Secrete products onto body surfaces or into body cavities
Mucus, sweat, oil, salivary glands, liver (secretes bile), pancreas (secretes digestive enzymes) etc.
Endocrine Glands
Ductless glands, produce hormones
Goblet cells
Unicellular exocrine glands; cuplike accumulation of mucin distends the top of the cell (making it look like a glass with a stem)
Structural elements of connective tissue
3 Main elements: ground substance, fibers (collagen, reticular, elastic) , cells
Common Characteristics of Connective Tissues
Common origin (mesenchyme)
Degrees of vascularity
Extracellular matrix
Matrix
Ground substance (unstructured material that fills space between cells) + fibers
Cells of connective tissue proper
Fibroblasts, fibrocytes, defense cells, adipocytes. Binding tissue, resists tension, provides reservoir for water and salts, fat storage
Cells of Cartilage
Chondroblasts, chondrocytes
Resists compression, cushions, supports body structures
Cells of bone
osteoblasts, osteocytes
hard tissue, resists compression and tension; support
Connective tissue proper: loose CT: areolar
Gel-like matrix, all 3 fiber types, fibroblasts, macrophages, mast cells, some WBCs
Wraps and cushions organs, phagocytosis, inflammation
Widely distributed under epithelia of body
Connective tissue proper: loose CT: adipose
Sparse matrix, closely packed adipocytes (nucleus pushed to side by large fat droplet)
Provides reserve food fuel, insulates, supports and protects organs
Under skin in subcutaneous tissue, around kidneys and eyeballs, within abdomen, in breasts
Connective tissue proper: loose CT: reticular
Network of reticular fibers in loose ground substance
Fibers form soft internal skeleton (stroma) that supports other cell types
Location: lymphoid organs (lymph nodes, bone marrow, spleen)
Connective tissue proper: dense CT: regular
Primarily parallel (slightly wavy) collagen fibers, fibroblasts Attaches muscles to bones or to muscles, attaches bones to bones, withstands tension Tendons, most ligaments, aponeuroses
Connective tissue proper: dense CT: irregular
Primarily irregularly arranged collagen fibers, fibroblasts
Withstands tension
Location: fibrous capsules of organs and of joints, dermis of skin, submucosa of digestive tract
Connective tissue proper: dense CT: elastic
Dense regular CT with high proportion of elastic fibers
Allows tissue to recoil, maintains pulsatile flow of blood through arteries, aids recoil of lungs following inspiration
Location: walls of arteries, within some ligaments of vertebral column, w/in walls of bronchial tubes
Cartilage: Hyaline
Amorphous but firm matrix; collagen fibers ; chondroblasts produce matrix and when mature (chondrocytes) lie in lacunae
Supports and reinforces, cushions, resists compression
Forms most of embryonic skeleton, covers ends of long bones, costal cartilages of ribs, cartilages of nose, trachea, larynx
Cartilage: elastic
similar to hyaline cartilage, with more elastic fibers
maintains shape while allowing great flexibility
location: supports external ear (pinna); epiglottis
Cartilage: fibrocartilage
Matrix similar to but less firm than that in hyaline cartilage
Tensile strength, absorbs compressive shock
Location: intervertebral discs, pubic symphysis, discs of knee joint
Connective Tissue: Bone
Hard, calcified matrix containing many collagen fibers; osteocytes lie in lacunae
Function: supports and protects, lever for muscles, stores Ca and other minerals and fat, marrow is site for hematopoiesis
Connective Tissue: blood
Red and white blood cells in a fluid matrix (plasma)
Function: transports respiratory gases, nutrients, wastes, other substances
Location: within blood vessels
Nervous Tissue cell types
Neurons: electrically excitable cells (poor capacity to regenerate) Supporting cells (glia)
General Characteristics of Nervous Tissues
Regulates and controls body functions
Brain, spinal cord, nerves
Skeletal Muscle
Long, cylindrical, multinucleate cells; obvious striations
Voluntary movement; locomotion, facial expression
Location: in skeletal muscles attached to bones or occasionally to skin
Cardiac Muscle
Branching, striated, generally uninucleate cells that fit together at intercalated discs
Function: as it contracts, it propels blood into circulation
Location: walls of heart
Smooth Muscle
Spindle shaped cells with central nuclei, no striations, cells arranged closely
Propels substances or objects (food, urine, a baby) along internal passageways, involuntary control
Location: walls of hollow organs
