apk2100c chapter 4 - tissues

Basic tissue components

Cells

Extracellular matrix

Four basic tissue types

Epithelial (ET)

Connective (CT)

Muscular (MT)

Nervous (NT)

Epithelial tissue

cover body surfaces and lines hollow organs, body cavities, duct, and form glands

Connective tissue

• Protects, supports, and binds organs

• stores energy as fat

• provides immunity

Muscular tissue

generates physical force needed to make body structures move and generate body heat

Nervous tissue

detects changes in body and responded by generating nerve impulses/electrical signals (control)

Epithelial tissue arrangement

• continuous sheets (single or multiple layers)

• cells tightly packed and held together (little to no extracellular matrix)

Epithelial tissue location

Found at the boundary between two different environments

• Skin (boundary between outside vs inside)

Always have free surface (one side facing free open area like cavity)

Types of Epithelium

• Covering and lining

• Glandular

Covering and lining (ET)

• covering outer surfaces → skin

• lines inner surfaces → stomach

Glandular (ET)

• forms most glands of the body

• sweat glands, oil glands, milk glands, pituitary gland, etc.

• ex. produce sweat which goes to surface of skin

Epithelium tissue is what type of tissue?

Interface tissue: shared boundary/connection point

forms boundary between two diff areas

ET functions

• Protects underlying tissue

• Secretion - release products onto free surface; excretion of wastes

• Absorption (Selective barrier)

• Diffusion (SB)

• Filtration (SB)

• Sensory reception (has nerve endings)

High cellularity

• ET

• tons of cells

• lots of cells lined up, no extracellular matrix

Specialized contacts

• ET

• in order for cells to line up need these to attach to one another in continual sheets

Polarity

ET

• apical surface = faces the body surface, body cavity, lumen, duct

• basal surface = opposite of apical surface, adheres to the basement membrane ( anchored to thin sheet of connective tissue)

Apical surface (ET)

• faces the body surface, body cavity, lumen, duct

Basal surface (ET)

• opposite of apical surface, adheres to the basement membrane ( anchored to thin sheet of connective tissue)

Avascular

• ET

• no blood supply directly into ET

• No blood vessels into ET

Nervous innervation

• ET

• Nerve endings go into the ET

• ex. sense being pinched or something cold

Regeneration

ET

• high regenerative capacity

• high mitotic activity

  • undergo cell division quickly

• ex. skin paper cut heals quickly

Basal lamina

• basement membrane layer

• basal surface of epithelial cells will attach to directly

• secreted by epithelium

Reticular lamina

• deep to the basal lamina

• part of underlying connective tissue

Cell junctions (ET)

Specialized contacts between epithelial cells

• tight junctions

• adhesive belt

• desmosome

• gap junction

How ET are classified

Arrangement of cell layers

Shapes of cells

Simple arrangement (ET)

One single layer of E cells

Stratified arrangement (ET)

Multiple layers (more than one)

Squamous cell shape (ET)

• flat cell shape

• tile like cells

• nucleus bulges up while rest of cell flat

Cuboidal cell shape (ET)

• square like in nature

• round nuclear centrally located

Columnar cell shape (ET)

• column shape

• longer than it is wide

• nucleus oval-like shape

• nucleus more towards basal surface

How to classify when there are two cell shapes (ET)?

Look at what cell shape there is on apical surface

simple squamous ET description

• single layer

• flattened cells with disc shaped central nuclei and sparse cytoplasm

• simplest

simple squamous ET function

• Allows passage of materials by diffusion/readily

• Filtration in sites where protection is not important

• Produces lubricating fluid in serosae

simple squamous ET location

• kidney glomeruli (site of filtration for blood to get made into urine)

• air sacs of lungs (alveoli) = air needs to cross walls for o2 to get into bloodstream

• lining inside of heart

• ling of blood vessels = nutrient diffusion and gases

• lymphatic vessels

• lining of ventral body cavity (serosae)

  • visceral and parietal layers of serous membranes (made up of this)

simple cuboidal ET description

• single layer

• cubelike cells with large spherical central nuclei

simple cuboidal ET function

thicker cells allow for

• secretion

• absorption

• transport processes can happen

simple cuboidal ET location

• kidney tubules

• ducts and secretory portions of small glands

• ovary surface

Lumen

hollow space in middle of cells

simple columnar ET description

• single layer of tall cells

• round to oval nuclei - closer to the basal surface

• some cells have cilia

• some cells can have microvilli

• layer may contain mucus-secreting unicellular glands (goblet cells)

simple columnar ET function

• absorption

• secretion of mucus, enzymes, and other substances

• ciliated type propels mucus (or reproductive cells) by ciliary action

simple columnar ET location

Nonciliated type

• lines most of the digestive tract (stomach to anal canal)

• gallbladder

• excretory ducts of some glands

Ciliated variety lines

• small bronchi (mucus when sick to move up to throat)

• uterine/fallopian tubes (move egg)

• some regions of uterus

Pseudo stratified columnar ET description

• pseudo = fake

• looks like multiple layers, but only one

• all cells bound to the basement membrane, no multiple layers

• single later of cells of differing heights

  • some do not reach free surface

• nuclei seen at different levels

• may contain mucus-secreting goblet cells and bear cilia

Pseudo stratified columnar ET function

• secretion of mucus (goblet cells)

• propulsion of mucus by ciliary action

Pseudo stratified columnar ET location

Nonciliated

• male’s sperm-carrying ducts

• ducts of large glands

Ciliated

• lines trachea

• most of upper respiratory tract

Stratified squamous ET description

• thick membrane with several layers

• basal cells are cuboidal or columnar → metabolically active

• surface cells → squamous

• keratinized type

  • surface cells are full of keratin and dead

• basal cells are active in mitosis and produce cells of more superficial layers

Stratified squamous ET function

• Protects underlying tissues in areas subjected to abrasion

  • even if top get scraped away bottom is still intact and there

Stratified squamous ET location

Nonkeratinized type

• forms moist linings of the esophagus, mouth, and vagina (if layers are removed, that’s okay because there are more underneath)

• places exposed to friction

Keratinized

• forms epidermis of skin, a dry membrane

• hardened layer of dead cells - initial dead keratinized cells

• external skin

Stratified cuboidal ET description

• generally two layers of cubelike cells

• quite rare to find

• large lumen and two rows of nuclei

Stratified cuboidal ET function

• protection

• layer along apical surface is cuboidal

Stratified cuboidal ET location

• largest ducts of sweat glands, mammary glands, and salivary glands

Stratified columnar ET description

• rare in body

• multiple layers

• basal cells usually cuboidal

• superficial cells elongated and columnar

Stratified columnar ET function

• protection

• secretion

Stratified columnar ET location

• rare in the body

• small amounts in the male urethra (urinary system)

• large ducts of some glands

Tight junction

• specialized contact

• lateral surface of cell (away from midline of cell)

• sides of cell

• interlocking junctional proteins = fuse membranes of two side by side cells

  • nothing can squeeze between the intracellular space

• impermeable barrier/junction

Desmosomes

aka (Anchoring junctions)

• formed by linker glycoproteins (cadherins)

• tons of space between two cells

• form internal tension-reducing network of fibers

• allows for movement but not detachment

Gap junctions

• channels or tunnels connecting two cells (proteins forming these channels = connexons)

• communicating junctions allow ions and small molecules to pass from cell to cell

  • intraceullar communication

Basal lamina is part of…

basement membrane

(but can be used interchangeably)

Microvilli

• found on apical surface

• facing free surface

• non-motile

• increase surface area

• microfilaments with actin

Cilia

• can be found in apical surface

• microtubules

• move things along surface of cell (motile)

Glands

ET that make and secrete a product

Secretions are aqueous fluids that usually contain proteins → exocytosed

What can glands secrete?

Hormones

Mucous

Sweat and oils

Bile and digestive enzymes

Milk

ET that make and secrete a product form…

glands

Endocrine glands

• secretion = hormones

• hormones released directly into ECF and diffuse into blood stream w/o duct

• effector organs (target) are far away

Exocrine glands

• secretion flow onto body surfaces or into cavities (onto free surface only)

  • NEVER bloodstream

• secretions act locally → effector organ is nearby

• Multicellular = multiple cells form gland that secrete product via duct (sweat glands)

• Unicellular = one-celled gland (goblet cell)

Goblet cell

• unicellular exocrine gland

• assoicated with columnar epithelial cells

• has vesicles that has mucin (glycoprotein)

• once mucin combines with water = mucus

multicellular exocrine gland

Has a duct(s) and secretory unit(s)

Simple tubular

• multicellular exocrine gland

• simple duct structure

• tubular secretory structure

• ex. intestinal glands

Simple branched tubular

• multicellular exocrine gland

• simple one duct

• multiple tubular secretory structures

Compound tubular

• multicellular exocrine gland

• Compound duct structure (multiple)

• Multiple tubular structures

• ex. duodenal glands of small intestine

Simple alveolar

• multicellular exocrine gland

• Simple duct structure

• Alveolar (circular) secretory structure = 1

Simple branched alveolar

• multicellular exocrine gland

• simple duct structure

• multiple alveolar structures

• ex. sebaceous (oil) glands

Compound alveolar

• multicellular exocrine gland

• Compound duct structure

• Multiple alveolar secretory structure

• ex. mammary glands

Compound tubuloalveolar

• multicellular exocrine gland

• compound duct structure/branches

• multiple alveolar secretory structures

• ex. salivary glands

Cutaneous membrane

Reference to skin

Mucous membranes

• line open cavities and organs

• tubes of respiratory, digestive, reproductive, urinary systems

Serous membranes

• line closed cavities

• thoracic and abdominal cavities (ventral body cavity)

Connective Tissue (CT)

• most diverse and abundant type of tissue

CT main categories

• CT proper

• Cartilage

• Bone

• Blood

CT general characteristics

• few cells

• lots of extracellular matrix

Where do ALL CT derive or originate from?

Mesenchyme

Immature cell

-blast = to bud, sprout, produce

Retain capacity for mitosis and secrete matrix

Mature cell

-cyte

• reduced capacity for cell division

• most involved in matrix maintenance

• doe not help with producing ground substance

Messenchyme cellular descendants

• Fibroblast

• Chondroblast

• Osteoblast

• Hematopoietic stem cell

Fibroblast

• Becomes a fibrocyte

• CT class: connective tissue proper

• CT proper subclasses

  • Loose connective tissue

    • types: areolar, adipose, reticular

  • Dense connective tissue

    • types: regular, irregular, elastic

Chondroblast

• Becomes chondrocyte

• CT class: cartilage

  • Hyaline cartilage

  • fibrocartilage

  • elastic cartilage

Osteoblast

• Becomes osteocyte

• CT class: Osseous (bone)

  • Compact bone

  • Spongy (cancellous) bone

Hematopoletic stem cell

• Becomes blood cells (and macrophages)

• CT class: blood

CT Matrix (extracellular matrix)

• contains protein fibers embedded in fluid, gel, or solid ground substance

• ground substance = gel-like environment that everything is sitting in

  • bone tissue = ground substance gets calcified

• fibers = collagen, elastic, and reticular (some CT will have more than another type of fiber)

ground substance (matrix)

• material filling space between cells and fibers

  • fluid, semifluid, gelatinous, or calcified

• functions to support and bind cells

• store water

• medium for exchange between blood and cells

• combo of proteins and polysaccharides

fibers (matrix)

• Synthesized by fibroblasts

• provides strength and support for tissues

• collagen, elastic, and reticular fibers

collagen fiber

• tough

• flexible

• resists stretching

• tensile strength

• largest (rope like)

elastic fiber

allows for stretch and recoil

branches form networks

long, thin fibers

reticular fiber

form spongelike framework for support

smallest

special collagen fibrils (very thick)

cluster into networks

Other CT cells

• fibroblasts

• adipocytes (fat cells)

• mast cells

• white blood cells

• macrophages

• plasma cells

fibroblasts

• secrete fibers and components of ground substance

• CT

adipocytes (fat)

• store triglycerides (fat) to be used later/energy

• CT

mast cells

• produce histamine (increase blood flow) and heparin (prevents blood clotting)

• CT

white blood cells

• immune response

• neutrophils and esinophils

• CT

macrophages

• Engulf bacteria and cellular debris by phagocytosis

• CT

Plasma cells

• secrete antibodies

• CT