A+P Chapter 4

Cells as a structural element of connective tissue Blast cells? (3)

"Blast" cells: Immature form of cell that actively secretes ground substance and ECM fibers Fibroblasts found in connective tissue proper Chondroblasts found in cartilage Osteoblasts: found in bone Hematopoietic stem cells in bone marrow "Cyte" cells §Mature, less active form of "blast" cell that now becomes part of and helps maintain health of matrix

CT proper: loose connective tissues -Areolar connective tissue

- Most widely distributed CT - Supports and binds other tissues §Universal packing material between other tissues -Contains fibroblasts that secrete loose arrangement of mostly collagen fibers -Loose fibers allow for increased ground substance, which can act as water reservoir by holding more interstitial fluid - Macrophages and fat cells are contained in spaces

•CT proper: loose connective tissues -Reticular connective tissue

- Resembles areolar tissue, but fibers are thinner reticular fibers -Fibroblast cells are called reticular cells -Secrete reticular fibers made up of thin collagen - Reticular fibers form a mesh-like stroma that acts as a support for blood cells in lymph nodes, spleen, and bone marrow

CT proper: dense connective tissues -Dense irregular connective tissue

- Same elements as dense regular, but bundles of collagen are thicker and irregularly arranged - Forms sheets rather than bundles -Resists tension from many directions Found in: -Dermis -Fibrous joint capsules -Fibrous coverings of some organs

CT proper: dense connective tissues -Elastic connective tissue

- Some ligaments are very elastic Example: ligaments connecting adjacent vertebrae must be very elastic Also found in walls of many large arteries -Arteries need to stretch when blood enters and recoil to push blood out

"Supported by connective Tissues" as a Special characteristic of Epithelial tissue

-All epithelial sheets are supported by connective tissue. -Reticular lamina Deep to basal lamina. Consists of network of collagen fibers. -Basement membrane Made up of basal and reticular lamina. Reinforces epithelial sheet. Resists stretching and tearing. Defines epithelial boundary. Cancerous epithelial cells are not contained by the basement membrane boundary like other cells. They penetrate the boundary and invade underlying tissues, resulting in spread of cancer.

Bone as a connective tissue - osteoblasts - osteocytes - osteons

-Also called osseous tissue -Supports and protects body structures -Stores fat and synthesizes blood cells in cavities -Has more collagen compared to cartilage -Has inorganic calcium salts -Osteoblasts produce matrix -Osteocytes maintain the matrix §Reside in cavities in matrix called lacunae -Osteons: individual structural units -Richly vascularized

Tissue with virtually no functional regerative capacity

-Cardiac muscle and nervous tissue of brain and spinal cord -New research shows cell division does occur, and efforts are underway to coax them to regenerate better

4 main classes of connective tissue

-Connective tissue proper -Cartilage -Bone -Blood

"Regeneration" as a special characteristic of epithelial Tissues

-Epithelial cells have high regenerative capacities -Stimulated by loss of apical-basal polarity and broken lateral contacts -Some cells are exposed to friction, some to hostile substances, resulting in damage Must be replaced. Requires adequate nutrients and cell division.

Tissues that repair extremely well

-Epithelial tissues - bone - areolar connective tissue - dense irregular connective tissue -blood-forming tissue

"Specialized contacts" as a specialized characteristic of Epithelial Tissues.

-Epithelial tissues need to fit closely together Many form continuous sheets -Specialized contact points bind adjacent epithelial cells together Lateral contacts include: -Tight junctions -Desmosomes

To be viewed under a microscope, tissue must be:

-Fixed: tissue is preserved with solvent -Sectioned: cut into slices thin enough to transmit light or electrons -Stained: to enhance contrast, although artifacts (distortions) detract from what the sample looks like in living tissues -Light microscopy uses colored dyes -Electron microscopy uses heavy metal coatings

Smooth Muscle

-Found mainly in walls of hollow organs (other than heart) -Involuntary muscle -Has no visible striations -Spindle-shaped cells with one nucleus

3 main elements of connective tissues

-Ground substance -Fibers -Cells *The first two elements (ground substance and fibers) together make up the extracellular matrix *Composition and arrangement of these three elements vary considerably in different types of connective tissues

How can Scar tissue that forms in organs, particularly the heart, can severely impair the function of that organ

-May cause the organ to lose volume capacity -May block substances from moving through organ -May interfere with ability of muscles to contract or may impair nerve transmissions -Scar adhesions may cause organs to adhere to neighboring structures, preventing normal functions -Scarring can potentially cause progressive failure of the organ, particularly the heart

Hyaline Cartilage

-Most abundant; "gristle" -Appears as shiny bluish glass -Found at tips of long bones, nose, trachea, larynx, and cartilage of the ribs

Multicellular exocrine Glands - composed of? - surrounded by? - classified by? - Structure?

-Multicellular exocrine glands are composed of a duct and a secretory unit -Usually surrounded by supportive connective tissue that supplies blood and nerve fibers to gland Connective tissue can form capsule around gland, and also extend into gland, dividing it into lobes -Classified by: Structure Mode of secretion Structure: -Simple exocrine glands have unbranched ducts, but compound glands have branched ducts -In a tubular gland, secretory cells form a duct, whereas in alveolar glands, secretory cells form sacs Tubuloalveolar glands have both types

"Avascular, but innervated" as a special characteristic of Epithelial tissue

-No blood vessels are found in epithelial tissue Must be nourished by diffusion from underlying connective tissues -Epithelia are supplied by nerve fibers, however.

Exocrine Glands

-Secretions are released onto body surfaces, such as skin, or into body cavities -More numerous than endocrine glands -Secrete products into ducts -Examples include mucous, sweat, oil, and salivary glands -Can be: Unicellular Multicellular

Elastic Cartilage

-Similar to hyaline but with more elastic fibers -Found in ears and epiglottis

CT proper: dense connective tissues Dense regular connective tissue

-Very high tensile strength; can withstand high tension and stretching -Closely packed bundles of thick collagen fibers run parallel to direction of pull -Fibers appear as white structures •Great resistance to pulling -Fibers slightly wavy, so stretch a little - Fibroblasts manufacture collagen fibers and ground substance -Very few cells and ground substance, mostly fibers -Poorly vascularized -Example: tendons and ligaments

Common Characteristics of connective tissues (3)

1. All have common embryonic origin: all arise from mesenchyme tissue as their tissue of origin 2. Have varying degrees of vascularity (cartilage is avascular, bone is highly vascularized) 3. Cells are suspended/embedded in extracellular matrix (ECM) (protein-sugar mesh) Matrix supports cells so they can bear weight, withstand tension, endure abuse

5 distinguishing characteristics of Epithelial Tissue

1.Polarity 2. Specialized contacts 3. Supported by connective tissues 4. Avascular, but innervated 5. Regeneration

Skeletal Muscle

Attached to and causes movement of bones Also called voluntary muscle -Skeletal muscles can be consciously controlled Cells are called muscle fibers -Contain multiple nuclei -Appear striated or banded

Connective tissue proper (CT Proper)

Consists of all connective tissues except bone, cartilage, and blood -Two subclasses CT proper: loose connective tissues -Areolar -Adipose -Reticular CT proper: dense connective tissues -Dense regular -Dense irregular -Elastic

Transitional Epithelium Description Function Location

Description: Resembles both stratified squamous and stratified cuboidal; basal cells cuboidal or columnar; surface cells dome shaped or squamouslike, depending on degree of organ stretch. Function: Stretches readily, permits stored urine to distend urinary organ. Location: Lines the ureters, bladder, and part of the urethra.

Stratified Squamous Epithelium -Description -Function -Location

Description: Thick epithelium composed of several cell layers; basal cells are cuboidal or columnar and metabolically active; surface cells are flattened (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. Location: Nonkeratinized type forms the moist linings of the esophagus, mouth, and vagina; keratinized variety forms the epidermis of the skin, a dry epithelium. Function: Protects underlying tissues in areas subjected to abrasion

pseudostratified columnar epithelium -Description -Function -Location

Description: single layer of cells o differing heights, some not reaching the free surface; nuclei seen at different levels; may contain mucus-secreting cells and bear cilia Location: ciliated variety lines the trachea and most of the upper respiratory tract; nonciliated type in males' sperm carrying ducts, and ducts of large glands Function: secrete substances, particularly mucus; propulsion of mucus by cilliary action.

Simple cuboidal epithelium -Description -Function -Location

Description: single layer of cube-like cells with large, spherical central nuclei Location: Kidney tubules; ducts and secretory portions of small glands; ovary surface Function: secretion and absorption.

Simple Squamous Epithelium -Description -Function -Location

Description: single layer of flattened cells with disc shaped central nuclei and sparse cytoplasm; the simplest of the epithelia Location: Kidney glomerull; air sacs of lungs; lining of heart, blood vessels, and lymphatic vessels; serosae Function: Allows materials to pass by diffusion and filtration in sites where protection is not important; secretes lubricating substances in serosae (linings of ventral body cavities)

Simple columnar epithelium -Description -Function -Location

Description: single layer of tall cells with round to oval nuclei; many cells bear microvili, some bear cilia; layer may contain mucus secreting unicellular glands (goblet cells) Location: nonciliated type lines most of the digestive tract (stomach to rectum), gallbladder and excretory ducts of some glands; ciliated variety lines small bronchi, uterine tubules, and some regions of the uterus Function: absorption, secretion of mucus, enzymes, and other substances; ciliated type propels mucus (or reproductive cells) by ciliary action

Cardiac Muscle

Found only in walls of heart Involuntary muscle Like skeletal muscle, contains striations; but cells have only one nucleus Cells can have many branches that join branches of other cardiac cells -Intercalated discs are special joints where cardiac cells are joined

Tissues

Groups of cells similar in structure that perform common or related function

3 types of cartilage (which is a connective tissue)

Hyaline Elastic Fibrocartilage

Epithelial Tissue What are they? - 2 main forms - Functions?

Is a sheet of cells that covers body surfaces or cavities Two main forms: -Covering and lining epithelia On external and internal surfaces (example: skin) -Glandular epithelia Secretory tissue in glands (example: salivary glands) Main functions: protection, absorption, filtration, excretion, secretion, and sensory reception

Nervous Tissue

Main component of nervous system (brain, spinal cord, nerves) -Regulates and controls body functions Made up of two specialized cells: -Neurons: specialized nerve cells that generate and conduct nerve impulses -Supporting cells that support, insulate, and protect neurons

Cartilage as a type of connective tissue

Matrix secreted from chondroblasts (during growth) and chondrocytes (adults) -Chondrocytes found in cavities called lacunae -80% water, with packed collagen fibers and sugar proteins (chondroitin and hyaluronic acid) Tough yet flexible material that lacks nerve fibers Avascular: receives nutrients from membrane surrounding it (perichondrium) §Periochondrium gives rise to chondroblasts and chondrocytes •Avascular cartilage loses ability to divide as we age, so injuries heal slowly -Common in people with sports injuries

Multicellular exocrine glands mode of secretion? (3)

Merocrine: most secrete products by exocytosis as secretions are produced (sweat, pancreas) Holocrine: accumulate products within, then rupture (sebaceous oil glands) Apocrine: accumulate products within, but only apex ruptures; whether this type exists in humans is controversial (maybe mammary cells?)

Blood as a connective tissue

Most atypical connective tissue because it is fluid - Consists of cells surrounded by matrix (plasma) Red blood cells are most common cell type Also contains white blood cells and platelets Fibers are soluble proteins that precipitate during blood clotting Functions in transport and in carrying nutrients, wastes, gases, and other substances

Gland

One or more cells that makes and secretes an aqueous fluid called a secretion

Fibrocartilage

Properties between hyaline and dense regular tissue Strong, so found in areas such as intervertebral discs and knee

simple epithelia vs stratified epithelia and function

Simple: a single layer thick. Involved in absorption, secretion, or filtration processes Stratified: 2 or more layers thick and involve din protection (ex. Skin)

Tissues with moderate regenerating capacity

Smooth muscle dense regular connective tissue

Squamous, Cuboidal, Columnar

Squamous: flattened and scale like cells Cuboidal: box-like, cube cells Columnar: tall, column like cells *In stratified epithelia, shape can vary in each layer, so cell is named according to the shape in apical layer

Tissue repair step 1

Step 1: Inflammation sets stage Release of inflammatory chemicals causes: -Dilation of blood vessels -Increase in blood vessel permeability -Clotting of blood occurs

Tissue Repair step 2

Step 2: Organization restores blood supply -Organization begins as the blood clot is replaced with granulation tissue (new capillary-enriched tissue) -Epithelium begins to regenerate -Fibroblasts produce collagen fibers to bridge the gap until regeneration is complete -Any debris in area is phagocytized

Tissue repair step 3

Step 3: Regeneration and fibrosis effect permanent repair -The scab detaches -Fibrous tissue matures -Epithelium thickens and begins to resemble adjacent tissue -Results in a fully regenerated epithelium with underlying scar tissue, which may or may not be visible

Fibers as a structural element of connective tissue - 3 types that provide support

Three types of fibers provide support: -Collagen Strongest and most abundant type. Tough; provides high tensile strength. -Elastic fibers Networks of long, thin, elastin fibers that allow for stretch and recoil -Reticular Short, fine, highly branched collagenous fibers (different chemistry and form from collagen fibers). Branching forms networks that offer more "give"

CT proper: dense connective tissues (what are the 3 varieties)

Three varieties of dense connective tissue -Dense regular -Dense irregular -Elastic

Ground substance as a structural element of connective tissue - what is it? - components? - example?

Unstructured gel-like material that fills space between cells - Medium through which solutes diffuse between blood capillaries and cells Components: - Interstitial fluid -Cell adhesion proteins ("glue" for attachment) - Proteoglycans (sugar proteins), made up of protein core + large polysaccharides Example: chrondroitin sulfate and hyaluronic acid *Water also is trapped in varying amounts, affecting viscosity of ground substance

CT proper: loose connective tissues -Adipose tissue

White fat -Similar to areolar tissue but greater nutrient storage -Cells are called adipocytes -Scanty matrix -Richly vascularized -Functions in shock absorption, insulation, and energy storage Brown fat -Use lipid fuels to heat bloodstream rather than to produce ATP, as does white fat

"Polarity" as a special characteristic of Epithelial tissue - Apical and Basal Surface?

cells have polarity (top and bottom) Apical surface: upper free side, is exposed to surface or cavity. Most apical surfaces are smooth, but some have specialized fingerlike projections called microvilli Basal Surface: lower attached side, faces inwards toward body. Attaches to basal lamina, an adhesive sheet that holds basal surface of epithelial cells to underlying cells

3 types of covering and lining membranes

cutaneous membranes, mucous membranes, serous membranes

Primary germ layers superficial to deep - when are they formed which of them form the 4 primary tissues

ectoderm, mesoderm, endoderm -Formed early in embryonic development -Specialize to form the four primary tissues -Nerve tissue arises from ectoderm -Muscle and connective tissues arise from mesoderm -Epithelial tissues arise from all three germ layers

4 basic tissue types

epithelial connective muscle nervous tissue

Endocrine gland

internally secreting ex.) hormones -Ductless glands Secretions are not released into a duct; are released into surrounding interstitial fluid, which is picked up by circulatory system -Secrete (by exocytosis) hormones, messenger chemicals that travel through lymph or blood to their specific target organs -Target organs respond in some characteristic way

Connective tissue - major functions

is the most abundant and widely distributed of primary tissues Major functions: binding and support, protecting, insulating, storing reserve fuel, and transporting substances (blood)

Unicellular exocrine Glands - the important ones? - found where? - what they produce?

mucous cells and goblet cells -Found in epithelial linings of intestinal and respiratory tracts -All produce mucin, a sugar-protein that can dissolve in water to form mucus, a slimy protective, lubricating coating

Serous Membrane

•Also called serosae •Found in closed ventral body cavities •Constructed from simple squamous epithelium (called mesothelium) resting on thin areolar connective tissue •Parietal serosae line internal body cavity walls •Visceral serosae cover internal organs •Cavity between layers is filled with slippery serous fluid, so these are moist membranes •Special names given to show location: pleurae (lungs), pericardium (heart), peritoneum (abdomen)

Cutaneous Membrane

•Another name for skin •Keratinized stratified squamous epithelium (epidermis) attached to a thick layer of connective tissue (dermis) •Unlike other membranes, skin is a dry membrane

generally, what is muscle tissue and what are the 3 types

•Highly vascularized •Responsible for most types of movement -Muscle cells possess myofilaments made up of actin and myosin proteins that bring about contraction •Three types of muscle tissues: -Skeletal muscle -Cardiac muscle -Smooth muscle

Mucous Membrane

•Mucosa indicates location, not cell composition •Also called mucosae -Line body cavities that are open to the exterior (example: digestive, respiratory, urogenital tracts) •Moist membranes bathed by secretions (or urine) •Epithelial sheet lies over layer of loose connective tissue called lamina propria •May secrete mucus