Lab 1: Histology & Integumentary System Tissue Types

simple squamous epithelium

description- single layer of flattened cells with disc-shaped central nuclei and sparse cytoplasm, simplest of epithelia

simple squamous epithelium

function- allows passage of materials by diffusion and filtration in sites where protection is not important, secretes lubricating substances in serosae (tissue lining of a body cavity or outer lining of an organ)

simple squamous epithelium

location- kidney glomeruli, air sacs of lungs, lining of heart, blood vessels and lymphatic vessels, lining of ventral body cavity

two types of simple squamous epithelium

endothelium, mesothelium

endothelium

provides a slick, friction-reducing lining in hollow organs that transmit bodily fluids (lymph, blood)

mesothelium

is the epithelium found in the serous membranes lining the ventral body cavity and covering its organs

simple cuboidal epithelium

description- single layer of cube like cells with large spherical central nuclei

simple cuboidal epithelium

function- secretion and absorption

simple cuboidal epithelium

location- kidney tubules, ducts and secretory portions of small glands, ovary surface

simple columnar epithelium

description-single layer of tall cells with round to oval nuclei, some cells bear cilia, layer may contain mucus-secreting unicellular glands (goblet cells)

simple columnar epithelium

function- absorption, secretion of mucus, enzymes and other substances, ciliated type propels mucus (or reproductive cells) by ciliary action

simple columnar location

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

stratified squamous epithelium

description- thick membrane composed of several layers, basal cells are 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

stratified squamous epithelium

function- protects underlying tissues in areas subjected to abrasion

stratified squamous epithelium

location- nonkeratinized type forms the moist linings of the esophagus, mouth, and vagina; keratinized variety forms the epidermis the skin, a dry membrane

psuedostratified ciliated columnar epithelium

description- 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

psuedostratified ciliated columnar epithelium

function- secretion, particularly of mucus, propulsion of mucus by ciliary action

psuedostratified ciliated columnar epithelium

location- nonciliated type in male’s sperm-carrying glands, ciliated variety lines the trachea, most of upper respiratory tract

transitiional epithelium

description- resembles both stratified squamous and statified cuboidal, basal cells cuboidal or columnar, surface cells dome shaped or squamous-like, depending on degree of organ stretch

transitiional epithelium

funciton- stretches readily and permits distention of certain hollow organs (bladder)

transitional epithelium

location- lines the ureters, urinary bladder, and part of the urethra

mesenchyme

an embryonic tissue, gives rise to all connective tissues

what makes up the extracellular matrix?

protein fibers and ground substance

what makes up ground substance?

collagen fibers, elastic fibers, and reticular fibers

fibroblasts

stationary cells that secrete proteins that join other molecules in the matrix to form fibers

mast cells

detect foreign microorganisms and initiate immune responses against them

adipocytes

fat cells and contain vacuoles for the storage of lipids

loose connective tissue

has an open network of protein fibers in a thick, syrupy ground substance and is divided into three groups

dense connective tissue

is made up of two types of fibers: protein fibers assembled into thick bundles of collagen and elastic fibers with widely scattered cells

what are the two types of dense connective tissue?

dense regular and dense irregular

dense regular connective tissue

protein fibers in the matrix are arranged in parallel bands

dense irregular connective tissues

fibers are interwoven, fibers that run in many directions and is found where tension is exerted from many different directions such as in the capsules of some organs and joints, the dermis of the skin and the submucosa of the digestive tract

two types of fluid connective tissue

blood and lymph

two types of supporting connective tissue

bone and cartilage

perichondrium

membrane that surrounds all supporting connective tissue and produces chondroblasts

lacunae

small spaces in the matrix where chondroblasts become trapped

chondrocytes

chondroblasts become chondrocytes after becoming trapped in the lacunae

three types of cartilage

hyaline, elastic, and fibrocartilage

areolar tissue

description- gel-like matrix with all three fiber types, cells: fibroblasts, macrophages, mast cells, and some white blood cells

areolar tissue

function- wraps and cushions organs, its macrophages phagocytize bacteria, plays important role in inflamation, holds and conveys tissue fluid

areolar tissue

widely distributed under the skin

adipose tissue

description-matrix as in areolar, but very sparse, closely packed adiposcytes (fat cells) have nucleus pushed to the side by large fat droplet

areolar tissue

function- provides reserve food fuel, insulates against heat loss, supports and protects organs

areolar tissue

location- under skin subcutaneous tissue around kidneys and eyeballs, within abdomen, in breasts

reticular tissue

description- network of reticular fibers in a typical loose ground substance, reticular cells lue on the network

areolar tissue

function- fibers form a soft internal skeleton (stroma) that supports other cell types including white blood cells, mast cells, and macrophages

reticular tissue

location- lymphoid organs (lymph nodes, bone marrow, and spleen)

dense regular connective tissue

description- primary parallel collagen fibers, a few elastic fibers, major cell type of the fibroblast

dense regular connective tissue

function- attaches muscles to bones or to muscles, attaches bone to bone, withstands great tensile stress when pulling force is applied in one direction

dense regular connective tissue

location- tendons, most ligaments, aponeuroses

dense regular elastic tissue

description- dense regular elastic tissue containing a high proportion of elastic fibers

dense regular connective tissue

allows recoil of tissue following stretching, maintains pulsatile flow of blood through arteries, aids passive recoil of lungs following respiration

dense regular connective tissue

location- walls of large arteries, within certain ligaments associated with the vertebral column, within the walls of the bronchial tubes

blood

description- red and white blood cells in a fluid matrix

blood

function- transport of respiratory gases, nutrients, wastes, and other substances

hyaline cartilage

description- amorphous but firm matrix, collagen fibers form an imperceptible network, chondroblasts produce the matrix and when mature

hyaline cartilage

function- supports and reinforces, has resilient cushioning properties, resists compressive stress

hyaline cartilage

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

elastic cartilage

description- similar to hyaline cartilage, but more elastic fibers in matrix

elastic cartilage

maintains the shape of a structure while allowing great flexibility

elastic cartilage

location- supports the external ear (pinna), epiglottis

fibrocartilage

description- matrix similar to but less firm than that in hyaline cartilage, thick collagen fibers predominate

fibrocartilage

function- tensile strength with the ability to absorb compressive shock

fibrocartilage

location- intervertebral discs, pubis symphysis, discs of knee joint

skeletal muscle

description- long cylindrical, multinucleate cells, obvious striations

skeletal muscle

function- voluntary movement, locomotion, manipulation in the environment, facial expression

skeletal muscle

location- in skeletal muscles attached to bones or occasionally to skin

muscle fibers

long cells that make up skeletal muscle

myoblasts

embryonic cells that fuse into one large cell to form the muscle fiber

myofilaments

intercontractile proteins that create a distinct band pattern (actin and myosin)

cardiac muscle

description- branching, striated, generally uninucleate cells that interdigitate at specialized junctions (intercalated discs)

cardiac muscle

function- as it contracts, it propels blood into circulation, involuntary control

cardiac muscle

location- the walls of the heart

what makes up skeletal muscle?

connective tissue layers generated by fibroblasts and contain endomysium between individual cells; cardiocytes are connected to one another via intercalated discs, which coalesce at ends of the cells in dense desmosome rich patches

smooth muscle

description- spinde-shapped cells with central nuclei; no striations, cells arranged closely to form sheets

smooth muscle

function- propels substances or objects (food, urine, or a baby) along interal passageways; involuntary control

smooth muscle

location- mostly in the walls of hollow organs

how are smooth muscles contracted?

induced and influenced by intracellular communication through gap junctions, hormones, mechanical stress, and different neurotransmitter

nervous tissue

description- neurons are branching cells, cell processes that may be quite long extend from the nucleus-containing cell body; also contributing to nervous tissue are the non-irritable supporting cells

nervous tissue

function- transmit electrical signals from sensory receptors and to effectors (muscles and glands)

nervous tissue

location- brain, spinal cord, nerves

what cells make up the nervous system?

neurons and glial cells

what is nerve tissue also known as?

neural tissue

effectors

a tissue/organ/structure in the body that processes information from sensory organs and responds with motor instructions to muscles and glands

neurons

cells responsible for receiving, interpreting, and sending the signals of the nervous system

cell body or soma

the central nucleus of a neuron

dendrites

fine extensions radiating out from the soma/cell body; receive signals from other cells and send this information to the soma

“trigger zone” of neuron

region where axon fuses to soma, where signals from dendrites are integrated’ determines if an action potential will be initated or not

periosteum

membrane that surrounds bone supporting tissue, contains osteoblasts

osteoblasts

in the periosteum, cells for bone growth and repair; secrete organic components of the matrix, become trapped in the lacunae and mature into osteocytes

osteocytes

matured osteoblasts

osteon (haversian system)

repeating structural units made of rings of concentric lamellae surrounding a central (haversian) canal that contains blood vessels and nerves

haversian canal

central canal of osteons

canaliculi

small channels in the lamellae that provide passageways through the solid matrix for diffusion of nutrients and wastes

osteoclast

bone destroying cells

in what two ways does bone ossify?

intramembranous bone (cranial bones and clavicle) develop from fibrous membranes and endochondral bone

perforating canal (Volkman’s canal)

runs perpendicular to the osteon; nerves, blood vessels, lymphatic vessels all pierce the periosteum and enter the bone in this canal; interconnects with the central canal

what comprises the integumentary system?

skin, sweat glands, oil glands, hair, nails

what is the purpose of the integumentary system?

give the body a protective barrier (flexible and resistant to everyday abrasions and water loss resistant), regulate body temp, house sensory receptors, ensure water homeostasis, protect body, manufacture vitamin D

what are the two main tissue layers of the skin?

epidermis (superficial and avascular), dermis (deep and vascularized)