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A group of similar cells that perform a common function; helps maintain homeostasis


Nonliving intercellular material that surrounds or embeds cells in a tissue/ some tissues contain almost no intercellular matrix, others almost entirely matrix with only few present/ some types have fibers that make them flexible or elastic; others have mineral crystals that make them rigid and others are very fluid


biology of tissues

Epithelial tissue

covers and protects the body surface, lines body cavities, specializes in moving substances into and out of the blood (secretion, excretion, and absorption), forms many glands/ CONTAINS NO BLOOD VESSELS/ said to be avascular/ desmosomes and tight junctions hold epithelial cells together/ cells can reproduce themselves

Connective tissue

supports the body and its parts; connects and holds them together, transport substances through the body, protect from foreign invaders/ cells relatively far apart and separated by large amounts of nonliving matrix

Muscle tissue

produces movement; moves body and its parts/ cells are specialized for contractility and produce movement by shortening of contractile units found in cytoplasm

Nervous tissue

most complex tissue in the body/ specializes in communication between various parts of the body and integration of their activites/ Major function- generation of complex messages for the coordination of body functions

Embryonic development of tissues

Four major tissues appear early (first two months after conception)/ After fertilization, repeated cell division converts single-celled zygote into hollow ball of cells called blastocyst


Hollow ball of cells/ implants in uterus/ within 2 weeks, cells move and regroup into three primary germ layers

Primary germ layers

Endoderm- epithelial/Mesoderm- epithelial, connective, muscle/Ectoderm-epithelial, nervous


process by which blastocysts cells move and then differentiate into the three primary germ layers/ cells in each germ layer become increasingly differentiated to form specific tissues


process of the primary germ layers differentiating into the different kinds of tissues

Membranous epithelium

covers the body and some of its parts and lines the serous cavities (pleural, pericardial, and peritoneal), blood and lymphatic vessels, and respiratory, digestive, and genitourinary tracts

Glandular epithelium

Grouped in solid cords or specialized follicles that form the secretory units of endocrine and exocrine glands/ speicialized for secretory acitivity/ function singly as unicellular glands or in clusters, solid cords, or specialized follicles as multicellular glands

Functions of Epithelial Tissue: Protection

most important function of membranous epithelium/ relatively tough and impermeable covering of the skin that protects the body from mechanical and chemical injury and also from bacteria and other disease-causing microorganisms

Functions of Epithelial Tissue: Sensory Function

found in skin, nose, eyes, and ears

Functions of Epithelial Tissue: Secretion

Glandular epithelium specialized for secretory activity, includes hormones, mucus, digesetive juices, and sweat

Functions of Epithelial Tissue: Absorption

lining epithelium of gut and respiratory tract allows for absorption of nutrients from gut and exchange of respiratory gases between air in lungs and blood

Functions of Epithelial Tissue: Excretion

epithelial lining of kidney tubules makes excretion and concentration of excretory products in urine possible

Basement membrane

thin noncellular layer of adhesive, permeable material

Basal lamina

glycoprotein material secreted by the epithelial cells

Reticular lamina

connective tissue fibers/ basal and this together form basement membrane


adhesive molecules that help bind cytoskeletons of epithelial cells to fibers of basement membrane, forming a strong connection


(Latin, "scaly") flat and plate-like


cube shaped and have more cytoplasm than squamous cells


higher than they are wide; look narrow and cylindrical

Pseudostratified columnar

one layer of odd shaped columnar cells (pseudo- false)

Simple epithelium

arrangement of epithelial cells in a single layer

Stratified epithelium

epithelial cells layered on one another

Transitional epithelium

unique arrangement of differing cell shapes in a stratified, or layered, epithelial sheet

Simple Squamous Epithelium

Consists of one layer of flat, scale-like cells/ substances can diffuse or filter/ microscopic air sacs (alveoli) of lungs are composed of this tissue, as well as linings of blood and lymphatic vessles and surfaces of pleura, pericardium, and peritoneum

Simple Cuboidal Epithelium

Composed of one layer of cuboidal cells resting on basement membrane/ seen in many glands and their ducts/ also found in ducts and tubules of other organs, such as kidneys

Simple Columnar Epithelium

Composes surface of mucous membrane that lines the stomach, intestine, uterus, uterine tubes, and parts of respiratory tract/ consists of single layer of cells/ three common modifications: Goblet cells, cilia, and microvilli

Goblet cells

large, secretory vesicles; vesicles contain mucus that goblet cells produce and secrete onto surface of epithlial membrane


Microscopic fingerlike projections in the intestine/ increases the surface area of intestinal mucous/ absorb nutrients and fluids from intestine

Psuedostratified Columnar epithelium

Found in lining of air passages of respiratory system and urethra in males/ only single layer of irregularly shaped columnar cells touch basement membrane/ mucus-secreting goblet cells are numerous and cilia is present

Stratified Squamous (Keratinized) Epithelium

Multiple layers of cells which flattened squamous cells at free, or outer surface of epithelial sheet/ keratin present in cells contributes to protective qualities of skin covering body surface

Stratified Squamous (Nonkeratinized) Epithelium

Found lining vagina, mouth and esophagus/ free surface is moist/ outer epithlial cells do not contain keratin/ serves as protective function

Stratified Cuboidal Epithelium

Serves as protective function/ can be located in sweat gland ducts, pharynx, and over parts of epiglottis

Stratified Columnar Epithelium

Mulptiple layers of columnar cells but only superficial cells are columnar in appearance/ found in male urethra and mucous layer near anus

Stratified Transitional Epithelium

Found in walls of urinary bladder that are subjected to tension and stress/ 10 or more layers of cuboidal cells present in absence of stretching or tension/ Cell shape changes from cuboidal to squamous in appearance

Structural Classification of Exocrine Glands

Multicellular glands often classified by structure, using shape of ducts and complexity (branching) of duct systems/ shapes include tubular and alveolar (saclike)/ simple exocrine glands have only one duct leading to surface/ compound glands have two or more ducts

Aporcine glands

collect secretory products near apex, tip, of cell and release into a duct by pinching off distended end; results in some loss of cytoplasm and damage to cell; recovery and repair of cell is rapid and continued secretion occurs; milk-producing mammary glands are examples


Such as sabaceous glands that produce oil to lubricate skin- collect secretory product inside cell and rupture to release it; SELF-DESTRUCT


discharge secretion product through cell or plasma membrane; completed without injury to cell wall or without loss of cytoplasm; secretion product passes from glandular cell into duct; salivary glands are an example

Functions of Connective Tissue

Connects, supports, transports, and defends/ Connects tissues to each other/muscles to muscles/ muscles to bone/ bones to bones/ supporting framework for the body as a whole and individual organs/ Blood is an example- transports large array of substances between parts of body/ Defend us against microorganisms and other invaders

Characteristics of Connective Tissue

Consists predominantly of intercellular material called matrix. Connective tissue's matrix contains one or more kinds of fibers: Collagenous (white), Reticular, Elastic


(White) Tough and strong; made of collagen; often occurs in bundles


Delicate; occur in networks; supports small structures such as capillaries and nerve fibers; made of a type of collagen called reticulun


Extensible and elastic; made of protein called elastin; returns to original length after being stretched; fibers found in "stretchy" tissues such as cartilage of external ear


Collagen in hydrated form is known as


Produces protein fibers/ most present in areolar tissue/ synthesize gel-like ground substance and fibers

4 major types of Connective tissue

Fibrous- loose, ordinary (areolar, adipose, reticular, dense
Cartilage- Hyaline, fibrocartilage, elastic

Fibrous Tissues

Have extracellular fibers as their predominant feature


Has fibers and a hard mineral ground substance


Has fibers and specialized ground substance that traps water to form a firm gel


Characterized by lack of fibers in the matrix

Fibrous Connective Tissue

Loose connective tissue is also called areolar tissue. Stretchable and most widely distributed of all tissues/ Matrix of areolar tissue is soft, thick gel because it contains hyaluronic acid


Second most present in areolar tissue/ AKA (histiocytes and resting wandering cells) Carry on phagocytosis/ classified as phagocytes/ derive from white blood cells


White blood cells/ found in loose ordinary connective tissue; occasional fat cells and some plasma cells (all mast cells)

Adipose Tissue

Contains predominantly fat cells and many fewer fibroblasts, macrophages, and mast cells/ supporting, protective pads around kidneys and various other structures/ constitutes a storage depot for excess food/ acts as an insulating material to conserve body heat

Reticular tissue

3D web, reticular network, identifies reticular tissue/ slender, branching reticular fibers with reticular cells overlying them/ branches of cytoplasm of reticular cells follow branching reticular fibers/ forms framework of spleen, lymph nodes, and bone marrow functions as part of body's complex mechanism for defending itself against injurious substances/ filters injurious substances out of blood and lymph/ Reticular cells phagocytose (engulf and destroy) them/ makes reticular fibers

Dense Fibrous Tissue

Consists mainly of fibers packed densely in the matrix/ contains relatively few fibroblast cells/ some dense fibrous tissues are designated as regular or irregular

Dense Fibrous (Regular) Tissue

Bundles of fibers arranged in regular, parallel rows/ composed of collagenous fibers and flexible but had great tensile strength/ desirable in structures that anchor muslce to bone such as tendons

Dense Fibrous (Irregular) Tissue

Ligaments (connect bone to bone) have predominance of elastic fibers/ bundles of fibers are not arranged in parallel rows/ fibers intertwine to form thick mat of strong connective tissue that can withstand stresses applied from any direction/ Forms strong inner skin layer called dermis/ also forms outer capsule of such organs such as kidney and the spleen

Bone Tissue

AKA osseous tissue/ organs of skeletal system/ provide support and protection for body and serve points of attachment for muscles/ calcified matrix of bones serves as a mineral reservoir for the body


Mature cells of bone embedded in matrix material containing both organic collagen material and mineral salts/ inorganic (bone salt) portion makes up about 65% of total matrix and responsible for hardness of bone/ located in small spaces, or lacunae, which are arranged in concentric layers of bone matrix called lamella


Small canals that connect each lacuna and osteocytes with nutrient blood vessels found in central Haversian canal.


Bone-forming cells


Bone destorying cells/ can dissolve the bone away from mature osteocyte and release it again to become an active osteoblast/ mature bones can grow and be reshaped by simultaneous activity of osteoclasts breaking down and remove existing bone tissue as osteoblasts lay down new bone

Membrane bones

(Flat bones of skull) formed within membranous tissue

Endochondral ossification

long bones such as humerus are formed indirectly through replacement of cartilage


Only cell present in cartilage/ produce fibers and tough, gristle-like ground substance of cartilage/ found in small openings, like bone cells, called lacunae/ Cartilage is avascular (lacking blood vessels), so nutrients must reach cells by diffusion/ movement is through matrix from blood vessels located in specialized connective tissue membrane called perichondrium/ injuries heal slowly because of inefficient method of nutrient delivery

Hyaline Cartilage

Low amount of collagen in matrix gives cartilage a shiny, translucent appearance/ most prevalent type of cartilage and found in support rings of respiratory tubes and covers end of bones that articulate at joints


Strongest and most durable type of cartilage, Matrix is rigid and filled with a dense packaging of strong white collagen fibers/ disks serves as shock absorbers between adjacent vertebrae (intervertebral disks) and in knee joint/ damage to fibrocartilage pads or joint menisci (curved pads) in the knee occurs frequently because of spot-related injuries

Elastic Cartilage

Contain few collagen fibers but large numbers of fine elastic fibers that give matrix material a high degree of flexibility/ found in external ear and voice box, or larynx

Connective Tissue: Blood

Most unusual connective tissue because it is liquid and contains neither ground substance nor fibers. Cells can be divided into three classes: Red Blood Cells, White Blood Cells, Platelets/ performs many body transport functions, including movement of respiratory gases (oxygen and carbon dioxide), nutrients and waste products/ plays critical role in maintaining a constant body temp and regulating pH of body fluids/ White blood cells destroy harmful microorganisms/ circulating blood tissue formed in red marrow of bones and in other tissues by process of differentiation called hematopoiesis

Red Blood cells


White Blood Cells




Hematopoietic tissue

Blood-forming tissue is sometimes given status of a separate connective tissue type

Skeletal muscle tissue

Composes muscles attached to bones; many cross striations, many nuclei per cell, and long, narrow, threadlike shape of cells

Smooth muscle tissue

sometimes called visceral muscle tissue, found in walls of viscera (hollow internal organs) also known as nonstriated involuntary/ has no cross striations and cannot ordinarily be controlled by the will/ long, narrow fibers but not as long as striated fibers/ have only one nucleus per fiber and are nonstriated or smooth in appearance


Makes up wall of heart/ also known as striated voluntary muscle/ has cross striations and contractions cannot ordinarily be controlled by will/ seem to be incomplete cells that branch into each other to form a big continuous mass of cytopasm (a syncytium)/ Electron microscope reveals that intercalated disks are places where plasma membranes of two cardiac fibers abut.


refers to cross striations (stripes) visible in microscopic slides of tissue


Indicated that voluntary or willed control of skeletal muscle contractions is possible

Nervous tissue characteristics

Basic function is to regulate activities of different parts of body/ much more developed excitability (ability of muscle to be stimulated) and conductivity characteristics than any other type organs of nervous system are brain, spinal cord, and nerves/ actual nervous tissue is ectodermal in origin and consists of two basic kinds of cells: nerve cells or neurons and neuroglia


Nerve cells/ conducting units of system/ all neurons characterized by a cell body called the soma and at least two processes: one axon and one or more dendrites/ most located within organs of central nervous system


transmits nerve impulses away from cell body


carry nerve signals toward axon


special connecting and supporting cells

Tissue Repair

Usually repair themselves by allowing phagocytic cells to remove dead or injured cells, then filling gaps that are left. (Process called regeneration) epithelial and connective tissues have greatest capacity to regenerate/ muslce tissue has limited capacity to regenerate and thus heal itself/ nerve tissue is also limited to regnerate

body membranes

refers to thin, sheet-like structure that may have important functions in the body/ cover and protects body surface, lines body cavities, covers inner surfaces of hollow organs such as digestive, reproductive, and respiratory passageways/ membranes secrete lubricating fluids that reduce friction during organ movements such as beating of the heart or lung expansion and contraction/ also decrease friction between bones and joints

Two major types of body membranes

Epithelial membranes- composed of epithelial tissue and an underlying layer of specialized connective tissue
Connective tissue membranes- composed exclusively of various types of connective tissue; no epithelial cells are present in this type of membrane

Epithelial membranes

Three types: Cutaneous membrane, serous membrane, mucous membrane

Cutaneous membrane

Covers body surfaces exposed to external environment/ skin is primary organ of integumentary system/ one of most important and largest and most visible of body/ composes appx 16% of body's weight/ fulfills requirements necessary for membrane in that it has a superficial layer of epithelial cells and underlying layer of supportive connective tissue

Serous membrane

Lines cavities that are not open to external environment and covers many of organs inside these cavities/ composed of two distinct layers of tissue (Epithelial sheet- thin layer of simple squamous epithelium/ Connective tissue layer- forms a very thin sheet that holds and supports epithelial cells)/ single sheet covering two different surfaces

Parietal membrane

portion that lines wall of cavity like wallpaper

Visceral membrane

covers surface of viscera (organs within the cavity)


surrounds a lung and lines thoracic cavity


covers abdominal viscera and lines abdominal cavity


surrounds the heart

Mucous membranes

epithelial membranes that line body surfaces opening directly to the exterior/ epithelial component of mucous membrane varies, depending on location and function/ get name from fact that they produce a film of mucus that coats and protects underlying cells/ acts as a lubricant for food as it moves along digestive tract/ serves as a sticky trap for contaminants in respiratory tract

Connective tissue membranes

do not contain epithelial components

Synovial membranes

lining spaces between bones and joints that move/ smooth and slick and secrete a thick and colorless lubricating fluid called synovial fluid/ helps reduce friction between opposing surfaces of bones in moveable joints/ also lines small, cushion-like sacs called bursae found between some moving body parts


literally means "new matter" and refers to abnormal growth of cells/ also called tumors/ can be distinct lumps of abnormal cells or, in blood tissue, can be diffused/ often classified as benign or malignant

Benign tumors

Do not spread to other tissues and usually grow very slowly; cells often well differentiated; cells tend to stay together and often are surrounded by a capsule of dense tissue/ usually not life-threatening but can be if they disrupt normal function of a vital organ.

Malignant tumors

AKA cancers/ not encapsulated and tend to spread to other regions of the body/ cells migrate by way of lymphatic or blood vessels/ process called metatiasis/ may replace part of a vital organ with abnormal, undifferentiated tissue- life-threatening situation

Compact bone

Tissue type composed of Haversian system

Dense fibrous connective tissue

strong tissue that forms tendons and ligaments

dense fibrous connective tissue 2

tissue type that forms strong membranes

cancellous bone

tissue type that forms hard material trabeculae

Cancellous bone 2

tissue type associated with red bone marrow

Fibrocartilage 2

connective tissue that forms the disks between vertebrae


tissue type that stores lipid molecules

fibrocartilage 3

cartilage type with a great deal of collagen in the matrix

dense fibrous connective tissue 3

tissue type that is actually modified areolar tissue

hyaline cartilage 2

the most common type of cartilage


identify a cell found in simple columnar and pseudostratified tissue that secretes mucus


one of two kinds of glands, it secretes substances onto epithelial surfaces


a cellular organelle, it is a projection that moves substances along the surface of a cell


a type of epithelial tissue especially well adapted to exceissve stretching


mucous membranes secrete this water-based protein solution


A tough waterproof material found in the upper layers of some examples of stratified squamous epithelium

Cuboidal 2

The type of epithelial tissue likely to be found forming glands

stratified squamous

the type of epithelial tissue likely to be found in the palm of the hand

cardiac and smooth

an involuntary muscle tissue is


which is most likely to be found in wall of urinary tract

neurons and glia

nerve tissue contains cells called


a voluntary type of muscle tissue is


nerve tissue forms the bulk of the

intercalated disks

cardiac muscle fibers are connected end to end by means of

skeletal muscle

which is most likely to have multiple nuclei

skeletal and cardiac

which muscle tissues is striated


T or F: fingerprint ridges are formed as a result of the orderly arrangement of dermal papillae

keratinezed stratified squamous

_______ epithelium form the epidermis

there are none present in the epidermis

which of the following answer choices would describe the presence of blood vessels in the epidermis?


Stratum basale and stratum ______ together may be called the stratum germinativum

adipose 2

the hypodermis is mainly areolar and _____ tissue


When you sense cold air around you, nerve ending in the epidermis are probably involved T or F


T or F the type of tissue that is found or that makes up the dermis is dense fibrous connective tissue


stratum basale is usually absent in thin skin and stratum lucidum is usually present


the dermis is ____ to the epidermis


The dermis is stronger than the epidermis


Blood vessels that supply the epidermis are found in the reticular region of the dermis


Strong shampoo tend to remove ____ from the hair and scalp, making it dry and easily damaged


_____ glands produce sebum


Waterproofing protein found in the skin is called


Stratum ____ is the epidermal stratum in which one could find many phases of mitosis

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