Lecture Exam 2 (Ch 4,5,6)

What are tissues?

Groups of cells that are similar in structure and function

What is histology?

study of tissues

What is fixation?

Preservation of a sample using a solvent before microscopic examination.

What is sectioning?

Cutting a sample into slices thin enough to transmit light or electrons.

What is staining?

A process used to enhance contrast in a sample, though it may introduce artifacts that distort its appearance compared to living tissue.

What are the differences between light microscopy, TEM, and SEM?

Light microscopy uses colored dyes; TEM uses heavy metal salts and shows a section; SEM uses heavy metal salts and shows a surface

What are the two main forms of epithelial tissue?

Covering and lining epithelium, and glandular epithelium.

What are the main functions of epithelial tissue?

Protection, absorption, filtration, excretion, secretion, and sensory reception.

What are the five distinguishing characteristics of epithelial tissue?

1. Polarity

2. Specialized contacts

3. Supported by connective tissue

4. Avascular but innervated

5. Regeneration

What is polarity in epithelial tissue?

Cells have distinct apical (free) and basal (attached) surfaces with different structure and function; apical faces a surface or cavity, basal attaches to the basal lamina.

What are specialized contacts in epithelial tissue?

Points where adjacent cells are tightly bound together to form continuous sheets.

What are the main lateral cell junctions in epithelial tissue?

Tight junctions and desmosomes

What supports epithelial tissue and what is its role?

Connective tissue supports epithelial sheets and helps reinforce them structurally.

What is the basement membrane and what does it do?

A structure made of the basal and reticular lamina that reinforces epithelium, resists stretching/tearing, and defines its boundary.

What happens when epithelial cells become cancerous in relation to the basement membrane?

They break through it, invade underlying tissues, and can spread to other areas of the body.

What does it mean that epithelial tissue is avascular but innervated?

It has no blood vessels and is nourished by diffusion from underlying connective tissue, but it does contain nerve fibers.

What is regeneration in epithelial tissue?

The rapid replacement of damaged or lost epithelial cells due to their high regenerative capacity.

How are epithelial tissues named based on layers?

How are epithelial tissues named based on layers?

How are epithelial tissues named based on cell shape?

Squamous (flat), cuboidal (cube-shaped), and columnar (tall/column-like); in stratified types, naming is based on the apical layer shape.

What is the main function of simple epithelial tissue?

Absorption, secretion, or filtration.

What is simple squamous tissue and where is it found?

Thin, flat cells specialized for rapid diffusion; found in places like lungs and kidneys, and forms endothelium (blood/lymph vessels, heart lining) and mesothelium (serous membranes).

What is simple cuboidal epithelium and where is it found?

A single layer of cube-shaped cells involved in secretion and absorption, found in kidney tubules and small gland ducts.

What is simple columnar epithelium and where is it found?

Single layer of tall cells for absorption and secretion; found in the digestive tract, gallbladder, bronchi, and uterine tubes.

What special structures and cell types may be found in simple columnar epithelium, and what do they do?

May have microvilli (increase absorption), cilia (move mucus), and goblet cells (secrete mucus).

What is pseudostratified columnar epithelium and where is it found?

Single layer of varying-height cells that appears multilayered; often ciliated; involved in mucus secretion and movement; found in the upper respiratory tract, ducts of large glands, and tubules in testes.

What is stratified epithelial tissue and how does it regenerate?

Tissue with two or more cell layers; basal cells divide and move upward to replace surface cells.

What is stratified squamous epithelium and where is it found?

Multiple layers with flat surface cells; found in high-wear areas like skin and moist linings (keratinized in skin, nonkeratinized in moist areas).

What is stratified cuboidal epithelium and where is it found?

A rare tissue, typically two layers thick; found in some sweat and mammary glands.

What is stratified columnar epithelium and where is it found?

A rare tissue with only the apical layer being columnar; found in the pharynx, male urethra, and some gland ducts, often at transition areas between epithelia.

What is transitional epithelium and where is it found?

A stretchable epithelium lining urinary organs; found in the bladder, ureters, and urethra, and allows expansion as it stretches for urine storage

What is a gland and what does it produce?

One or more cells that produce and secrete an aqueous fluid called a secretion

How are glands classified based on site of product release and cell number?

Endocrine (ductless, hormones), exocrine (release onto surfaces or into cavities), unicellular (goblet cells), and multicellular (e.g., salivary glands).

What are endocrine glands and how do they release their products?

Ductless glands that release hormones into interstitial fluid, which then enter the blood or lymph.

What are exocrine glands and how do they release their secretions?

Glands that release secretions onto body surfaces or into body cavities through ducts; more numerous than endocrine glands. (oil, mucus, sweat, etc.)

What are unicellular exocrine glands, what do they produce, and where are they found?

Single-celled glands (mucous cells/goblet cells) that produce mucin, forming mucus for protection and lubrication; found in intestinal and respiratory tract linings.

What are multicellular exocrine glands and what are they composed of?

Glands with multiple cells made of a duct and a secretory unit.

How are multicellular exocrine glands supported and classified?

Supported by connective tissue that may form a capsule and divide the gland into lobes; classified by structure and mode of secretion.

How are multicellular exocrine glands classified by duct structure?

Simple glands have unbranched ducts, while compound glands have branched ducts.

How are multicellular exocrine glands classified by secretory unit shape?

Tubular (tube-shaped), alveolar (sac-shaped), or tubuloalveolar (both types).

What is merocrine secretion and where does it occur?

Secretion by exocytosis without damaging cells; most common type, found in sweat glands, pancreas, and salivary glands

What are holocrine and apocrine secretion?

Holocrine releases whole cells when they rupture (e.g., sebaceous glands); apocrine releases only the cell apex (controversial if present in humans, mammary glands often considered merocrine, but closest example).

What is connective tissue and what are its main functions?

The most abundant and widely distributed tissue; functions include binding and support, protection, insulation, energy storage, and transport of substances.

What are the four main classes of connective tissue?

Connective tissue proper, cartilage, bone, and blood.

What makes connective tissue different from other primary tissues in terms of structure?

It has a large extracellular matrix in which cells are suspended, while other primary tissues are mainly made of cells.

What is the embryonic origin of connective tissue?

It arises from mesenchyme. (embyronic tissue)

What are the three main components of connective tissue?

Ground substance, fibers, and cells

What makes up the extracellular matrix in connective tissue?

Ground substance and fibers.

What is ground substance in connective tissue?

An unstructured gel-like material that fills spaces between cells and allows diffusion of substances between capillaries and cells.

What are collagen fibers and what is their function?

The strongest and most abundant connective tissue fibers; provide high tensile strength.

What are elastic fibers and what is their function?

Networks of long, thin elastin fibers that allow tissues to stretch and recoil.

What are reticular fibers and what is their function?

Short, fine, highly branched collagen fibers that form supportive networks with flexibility ("give").

What are "-blast" cells and "-cyte" cells in connective tissue?

"-blast" cells are immature and actively produce matrix; "-cyte" cells are mature and maintain the matrix, but can revert to "-blast" for repair.

What are mast cells and what is their role in connective tissue?

Cells that detect foreign microorganisms and trigger local inflammation by releasing chemicals like histamine and heparin.

What do macrophages do in connective tissue?

They break down foreign material and dead cells; they may be fixed in tissue or move freely through the matrix.

What is areolar (loose) connective tissue and what is its function?

The most widely distributed connective tissue; supports, binds, and acts as packing material between tissues.

What is the structure of areolar connective tissue?

Contains fibroblasts that produce loosely arranged collagen fibers, abundant ground substance, and may include macrophages and fat cells.

What is adipose (loose) tissue and what are its main functions?

A connective tissue made of adipocytes that stores energy, provides insulation, and absorbs shock; it is highly vascular and has little matrix.

What is the difference between white fat and brown fat?

White fat stores energy and provides insulation/shock absorption, while brown fat uses lipids to generate heat for the bloodstream instead of ATP.

What is reticular (loose) connective tissue and what is its structure?

A loose connective tissue similar to areolar tissue but with thin reticular fibers and reticular cells that produce them.

What is the function of reticular connective tissue?

Forms a supportive mesh (stroma) for blood cells in lymph nodes, spleen, and bone marrow.

What is dense regular connective tissue and what is its structure?

A connective tissue with tightly packed, parallel bundles of collagen fibers and few cells or ground substance. (poorly vascularized)

What is the function and location of dense regular connective tissue?

Provides very high tensile strength to resist pulling forces; found in tendons and ligaments.

What is dense irregular connective tissue and how is it structured?

A connective tissue with thicker collagen fibers arranged irregularly in sheets.

A connective tissue with thick collagen fibers arranged irregularly in sheets.

Provides strength and resists tension from many directions; found in the dermis, joint capsules, and organ coverings.

What is elastic (dense) connective tissue and what is its function?

A connective tissue rich in elastic fibers that allows stretching and recoil.

Where is elastic connective tissue found?

In elastic ligaments between vertebrae and in the walls of large arteries.

What is cartilage and what is its basic structure?

A tough, flexible connective tissue made of chondrocytes in lacunae and a matrix rich in water, collagen fibers, and proteoglycans.

How is cartilage nourished and maintained?

It is avascular and lacks nerves; nutrients diffuse in from the perichondrium (membrane) , which also produces new chondroblasts and chondrocytes.

What is hyaline cartilage and where is it found?

Most abundant cartilage ("gristle") with a shiny bluish appearance; found at ends of long bones, nose, trachea, larynx, and ribs.

What is elastic cartilage and where is it found?

Cartilage with more elastic fibers for flexibility; found in the ear and epiglottis

What is fibrocartilage and where is it found?

Strong cartilage with properties between hyaline and dense regular tissue; found in intervertebral discs and knee.

What is bone (osseous tissue) and what are its main functions?

A connective tissue that supports and protects structures, stores fat, and produces blood cells.

What is the structure and composition of bone tissue?

Contains more collagen than cartilage plus inorganic calcium salts; organized into osteons, with osteocytes in lacunae; highly vascularized.

What is blood and why is it considered an atypical connective tissue?

A fluid connective tissue made of cells suspended in plasma; it is atypical because its matrix is liquid.

What are the components and functions of blood?

Contains red blood cells, white blood cells, and platelets in plasma; transports nutrients, wastes, gases, and other substances.

What are the main features and function of muscle tissue?

Highly vascularized tissue responsible for movement; cells contain actin and myosin myofilaments that enable contraction.

What is skeletal muscle tissue and what does it do?

Muscle attached to bones that produces body movement; also called voluntary muscle.

What are key features of skeletal muscle cells?

Cells are multinucleated muscle fibers with a striated (banded) appearance.

What is cardiac muscle tissue and where is it found?

Involuntary, striated muscle found only in the walls of the heart

What are key structural features of cardiac muscle cells?

Cells are branched, usually have one nucleus, and are joined by intercalated discs.

What is smooth muscle tissue and where is it found?

Involuntary, non-striated muscle found in walls of hollow organs (except the heart).

What are the key features of smooth muscle cells?

Spindle-shaped cells with a single nucleus and no visible striations.

What is nervous tissue and what is its main function?

Tissue of the brain, spinal cord, and nerves that regulates and controls body functions.

What are the two main cell types in nervous tissue and what do they do?

Neurons transmit electrical signals via dendrites and axons; glial cells support, insulate, and protect neurons.

What are membranes in the body?

Organs made of more than one tissue type that cover and line

What is the cutaneous membrane and what is its structure?

Skin; made of keratinized stratified squamous epithelium (epidermis) attached to connective tissue (dermis), and it is a dry membrane

What are mucous membranes and where are they found?

Moist membranes lining body cavities that open to the exterior, including the digestive, respiratory, and urogenital tracts.

What is the structure and secretion pattern of mucous membranes?

Epithelial layer over lamina propria (loose connective tissue); often secrete mucus (digestive and respiratory), but urinary mucosa does not.

What are serous membranes and what do they do?

Moist membranes lining closed ventral body cavities that reduce friction using serous fluid; include pleurae, pericardium, and peritoneum. Made of simple squamous epithelium on thin areolar connective tissue.

What happens when body barriers are compromised?

The inflammatory and immune responses are activated to begin tissue repair, which starts quickly.

What are the two main ways tissue repair can occur?

Regeneration (same tissue replaces damaged tissue and restores function) and fibrosis (connective tissue replaces damaged tissue, leading to loss of original function).

What happens during the first step of tissue repair (inflammation)?

: Inflammatory chemicals cause blood vessels to dilate, increase permeability, and blood clotting begins.

What happens during the organization step of tissue repair?

A blood clot is replaced by granulation tissue, epithelium begins to regenerate, fibroblasts produce collagen to bridge the gap, and debris is removed by phagocytosis.

What happens during the final stage of tissue repair (regeneration and fibrosis)?

The scab detaches, fibrous tissue matures, and epithelium thickens and becomes similar to surrounding tissue.

What is the outcome of the final stage of tissue repair?

A fully regenerated epithelium with underlying scar tissue, which may or may not be visible.

Which tissues have high, moderate, and low regenerative capacity?

High: epithelial, bone, areolar CT, dense irregular CT, blood-forming tissue

Moderate: smooth muscle, dense regular CT

Low: cardiac muscle, brain and spinal cord nervous tissue.

What problems can scar tissue cause in organs?

It can reduce organ capacity, block movement of substances, and interfere with muscle contraction or nerve signaling.

What are the three primary germ layers and how are they arranged?

Ectoderm (superficial), mesoderm (middle), and endoderm (deep).

What tissues arise from each germ layer?

Ectoderm forms nervous tissue; mesoderm forms muscle and connective tissue; epithelial tissue can arise from all three layers.

What happens to tissues as the body ages?

Epithelia thin, repair becomes less efficient, bone/muscle/nervous tissues atrophy, and cancer risk increases due to more DNA mutations.