Unit 4: Key Terms A and P
Histology
study of normal structures of tissues
Tissues
group of structurally and functionally related cells and their external environment, together perform common functions
Extracellular matrix (ECM)
surrounding material of tissues
Epithelial Tissues
tightly packed sheets of cells with no visible ECM: cover and line all body surfaces and cavities
Connective Tissues
connect all other tissues to one another: cells scattered throughout ECM: bind, support, protect, and allow for transportation of substances
Muscle Tissues
capable of generating force by contractions, little ECM between cells
Nervous Tissues
capable of generating, sending, and receiving messages
Extracellular matrix cont.
substances in liquid, thick gel, or solid form that surrounds cells of tissue, 2 main components ground substance and protein fibers
Protein Fibers
embedded with ground substances, long molecules composed of multiple fibrous subunits with ropelike structures, enormous tensile strength, three types
Collagen Fibers
make up 20-25% of all proteins in the body, resistant to tension and pressure
Elastic Fibers
composed of protein elastin, extensibility allows fibers to stretch up to one and a half times resting length without breaking, once stretched, fibers return to resting length (elasticity)
Reticular Fibers
thin, short, collagen fibers, form meshwork or scaffold that supports cells and ground substance of many tissues, forming weblike structure in organs such as the spleen that helps trap foreign cells
Cell Junctions
another way cells bind to one another, linked by integral proteins, 1. Tight junctions 2. Desmosomes 3. Gap junction
Epithelial tissues
on every internal and external body surfaces, barrier, line organs and fluid-filled cavities
Esophagus
tubular organ, transports food from mouth to stomach
Avascular
lack blood vessels, must obtain oxygen and nutrients by diffusion from deeper tissues
Basement membrane
2 parts: Basal lamina and Reticular lamina
Basal lamina
ECM synthesized by epithelial cells, consists of collagen fibers and ground substance
Reticular lamina
synthesized by underlying connective tissue, consists of reticular fibers and ground substances
Epithelial tissue
classified by two criteria 1. number of cell layers 2. shape of cells in those layers
Simple epithelial
single cell layer
Stratified epithelial
more than one layer of epithelial
Squamous cells
flattend
Cuboidal cells
short, cubes
Columnar cells
tall and elongated
Simple squamous epithelium
very thin single-layer cells, "fried egg" appearance, rapid diffusion of substances, lining blood vessels
Simple cuboidal epithelium
a single layer of cube-shaped cells with a large central nucleus, rapid substance diffusion, in segments of renal tubules, respiratory passages, ducts of many glands, and thyroid gland
Simple columnar epithelium
single layer of rectangular-shaped cells with nuclei in basal portion of cell
Microvilli
small intestine
Cillia
uterine tubes and segments of respiratory tract
Pseudostratified columnar epithelium
appears layered because nuclei are at various heights, only one cell-layer thick, in segments of respiratory tract and nasal cavity, ciliated- trap foreign products
Stratified epithelium
more than one layer of cells, protective barriers where subjected to high degrees of mechanical stress
Stratified cuboidal epithelium
rare in humans, two cell layers, lines ducts of sweat glands
Transitional epithelium
only in the urinary system, lines all the urinary system, ability of optical cells to flatten allows cells to stretch
Gland
structure of epithelial origin, synthesizes and secretes product from designated secretory cells
Endocrine
secretes products: usually hormones directly into bloodstream without use of ducts
Exocrine
release products onton apical surfaces of epithelium (external surface of body) or lining hollow organ
Merocrine
used by majority of exocrine glands, including salivary and sweat glands
Holocrine
used by sebaceous glands in skin to secrete sebum, shed and ruptured cells
Apocrine
rare type of secretion ex: lactating mammary glands of many mammal species , part of cell pinches off
Connective tissue
two types, differ in cell types and ECM, connecting and binding, support, protection, transport
Fibroblasts
type of connective tissue proper, the most common permanent cell, makes protein fibers and ground substance, continually produce collagen proteins
Apeolor tissue (Loose connective tissue)
mostly ground substances, beneath the epithelium of skin, in membranes lining body cavities, and within walls of hollow organs, contain and support blood vessels vital to avascular epithelial tissues
Apidose tissue
loose connective tissue, fat-storing adipocytes and surround fibroblasts and ECM, fat storage, insulation, shock absorption and protection
Adipocytes
fats cells, cytoplasm filled with a single large lipid inclusion
Reticular tissue
loos connective tissue, networks of reticular fibers, blood, and lymphatic vessels, lymph nodes, spleen
Dense regular connective tissue
organized in parallel collagen bundles, in tendons and ligaments, subject to tension in one plane of movement
Dense irregular connective tissue
predominantly disorganized collagen bundles, resists tension in all 3 places of movement, organs and joints
Dermis
deep to skin
Elastic Tissue
mostly parallel-oriented elastic fibers with randomly oriented collagen fibers, in walls of organs that must stretch to function (large blood vessels and certain ligaments)
Specialized connective tissues
more specific functions, 3 types: cartilage, bone tissue, blood
Cartilage
tough, flexible tissue, absorbs shock and resits tension, compression, and shearing forces, 2 cell types: chondroblasts, chondrocytes
Chondroblasts
cartilage cell, immature cells, divide by mitosis and make most of ECM
Chondrocytes
cartilage cells, mature, surround themselves in small cavities (lacunae)
Hyaline Cartilage
most abundant, small bundles of fine collagen, on ends of bones in joints, linking the sternum to ribs, framing sections of the respiratory tract, and in the nose
Fibrocartilage
filled with bundles of collagen fibers, little room for ground substance in ECM
Elastic Cartilage
mostly elastic fibers in ECM, allows tissue to vibrate, external ear, larynx
Bone
supports body, protects vital organs, provides attachments for muscles that allow for movement, stores calcium, and houses bone marrow
Blood
unique, ECM is fluid
Plasma Proteins
not like fibers found in connective tissue, smaller with a variety of functions, transport of substances and blood clotting
Erythrocytes (red blood cells)
bind to and transport oxygen throughout the body
Leukocytes (white blood cells)
function in immunity
Platelets
cell fragments, major role in blood clotting
Muscle tissue
specialized for contraction, 3 types share ability to turn chemical energy of ATP into mechanical energy of movement
Skeletal muscle tissue
mostly attached to skeleton contraction produces body movement, voluntary, striated, multiple nuclei
Cardiac muscle tissue
only in the heart, cardiac muscle cells, striated, involuntary, intercalated disc
Smooth muscle tissue
consists of smooth muscle cells contractions are involuntary, nonstriated, one centrally located ovoid nucleus
Nervous tissues
brain, spinal cord, and nerves, two main cell types
Neurons
send and receive messages
Neuroglial cells
perform various functions, support neuron activities
Organ
two or more tissues that combine structurally and functionally