TISSUES

TISSUES

- Grps of specialized cells and the extracellular substances surrounding them
- Structure of ? informs you the function or portion of the organ, where the ? is found
- Grp of cells w/ similar structure and function
- covers and protects surfaces, both inside and outside
- Ex.: bone is the densest ? and provides protection for our body

HISTOLOGY

- Microscopic study of tissue structure
- Microscopic examination of tissue \= can identify abnormalities, including cancer, resulting from changes in tissue

Epithelial

covering or lining of the tissue either inside or outside

Connective

a diverse primary tissue type that makes up part of every organ in the body

Muscle

a tissue that contracts or shortens, making mvmt possible

Nervous

responsible for coordinating and controlling many body activities

EPITHELIUM

- Found virtually everywhere (both inside and outside of the body)
- Primarily a cellular tissue \= very little extracellular material bet. cells
- Forms the layers that cover the surfaces and line the hollow organs
- Important in hollow organs w/ openings to outside environment bc it protects against foreign materials entering the body

Mostly composed of cells

- characteristics of epithelial tissue
- Consists almost entirely of cells w/ very little extracellular matrix bet. them

Covers body surfaces

- characteristics of epithelial tissue
- ? and forms glands that are derived developmentally from body surfaces

Body surface

exterior surface, lining of the digestive urinary, reproductive, and respiratory tracts, heart and blood vessels, and the linings of body cavities

Has an exposed surface

- characteristics of epithelial tissue
- One surface of their cells is in direct contact w/ outside environment or the contents of our hollow organs
- Ex.: skin \= contact w/ atmosphere; lining of stomach \= food we eat

Free Surface or Apical Surface

- surface that is exposed
- always points toward the space inside a hollow organ/external envi.
- not attached to other cells

hollow organ or external environment

Free surface always points toward the space inside a ?

superficial

Only the most ? (pinaka outer) layer of cells is in contact w/ environment

Lateral Surface

cells are attached to other epithelial cells

Basement Membrane

- attach the epi cells to the underlying tissues.
- supports and guides the cell migration during tissue repair
- Nonliving material
- Composed of specialized extracellular material secreted by the epithelial cells
- Typically porous and regulates the mvmt of substances to and from the epithelial tissue above it

Basal Surface

- surface of the cell anchored in place
- Held in place thru attachment to a nonliving material (like mortar for brick)
- Always points toward the basement membrane but only the deepest layer of cells is in contact with BM
- base of the cell
- attached to the basement membrane

Has specialized cell connections and matrix attachments

- characteristics of epithelial tissue
- Adjacent epi cells are attached to each other by specialized cell connections
- Specially anchored to the extracellular matrix of the basement membrane

Is avascular/Nonvascular

- characteristics of epithelial tissue
- No blood vessels in the epi cells bc they are closely connected
- Blood vessels don't penetrate the basement mem
- They lie underneath BM, and nutrients & gases diffuse out of the blood toward the epi cells
- Outermost cells receive the nutrients and gases that have diffused thru the cells in the deeper layer
- Most metabolically active cells are closest to the BM

Is capable of regeneration

- characteristics of epithelial tissue
- Has the ability to replace damaged cells w/ new epi cells
- Undifferentiated cells (stem cells) continually divide and produce new cells
- Some epi tissues like in the skin and digestive tract continuously replace cells that die

Protecting underlying structures

- function of epithelia
- Ex: outer layer of skin and the epithelium of the oral cavity which protect the underlying structures from abrasion

Acting as a barrier

- function of epithelia
- Prevents many substances moving thru it
- Ex: epithelium of the skin \= acts as a barrier to water, thus reduces water loss from the body; prevents toxic mols and microorganisms from entering the body

Permitting the passage of substances

- function of epithelia
- Allows many substance to move thru it
- Ex: oxygen and CO2 are exchanged bet. the air and blood diffusion thru the epithelium in the lungs

Secreting Substances

- function of epithelia
- Sweat glands, mucous glands, and enzyme-secreting portion of the pancreas are all composed of epi cells

Absorbing Substances

- function of epithelia
- Cell mem of certain epi tissues contain carrier proteins that regulate the absorption of materials
- Ex: epi cells of intestines absorb digested food mols, vitamins, and ions

SIMPLE EPITHELIUM

- Consists of a single layer of cells
- Each cell extending from the basement membrane to the free surface

STRATIFIED EPITHELIUM

* more than 1 layer of cells
* Only the deepest layer of cells (basal layer) attaches to the BM

PSEUDOSTRATIFIED COLUMNAR EPITHELIUM

- Special type of simple epithelium
- Appears to be stratified but it is not
- 1 layer of cells with all the cells attached to the BM
- Appears to be 2 or more layers of cells bs some of the cells are tall and extended to the free surface, whereas others are shorter and do not extend to the free surface

SQUAMOUS CELLS

Flat or scalelike cells

CUBOIDAL CELLS

* Cubelike cells
* cube-shaped, about as wide as they are tall

COLUMNAR CELLS

- Tall and thin, similar to a column
- Tend to be taller than they are wide

SIMPLE SQUAMOUS EPITHELIUM

* Single layer of thin, flat cells 


* Some substances easily pass thru 
* Ex: SSE in lungs allows for gas exchange

SIMPLE CUBOIDAL EPITHELIUM

* Single layer of cubelike cells


* Carry out active transport, facilitated diffusion, or secretion
* Have greater secretory capacity than SSE

SIMPLE COLUMNAR EPITHELIUM

\
* Single layer of tall, thin cells
* Large size enables them to perform complex functions, such as secretion
* SCE of small intestine produces and secretes mucus and digestive enzymes

PSEUDOSTRATIFIED COLUMNAR EPITHELIUM

\
* Single layer of cells, but appear to be layered due to differing heights of adjacent cells and positions of their nuclei
* Provides protection for the body
* secretes mucus, which covers its free surface
* cilia in the airways move the mucus and accumulated debris toward the throat, where it is swallowed

STRATIFIED SQUAMOUS EPITHELIUM

\
* Thick epithelium bc it consists of several layers or cells
* Deepest cells are cuboidal or columnar 
* Capable of dividing and producing new cells
* Newly formed cells are pushed to the surface, and becomes flat and thin
* Naming is based on the __shape__ of the surface cells
* Keratinized Stratified Squamous Epithelium
* Nonkeratinized STRATSE

Keratinized Stratified Squamous Epithelium

* outer layer of skin
* reduces the loss of water from the body

Nonkeratinized Stratified Squamous Epithelium

* provides protection against abrasion and acts as a mechanical barrier
* STRATSE of the mouth is a moist ?
* water can move across it more readily than across the skin (keratinized strat squamous)

STRATIFIED CUBOIDAL

\
* more than one layer of cuboidal epithelial cells
* Absorption, secretion, protection
* Found in sweat gland ducts, ovarian follicular cells, and salivary glands

STRATIFIED COLUMNAR EPITHELIUM

* more than 1 layer of epi cells
* surface cells are columnar, but deeper cells are irregular or cuboidal in shape
* found in mammary gland ducts, larynx, and a portion of the male urethra
* carries out secretion, protection, and some absorption

TRANSITIONAL EPITHELIUM

* special type of stratified epithelium that can be greatly stretched
* shape of cells change as the epi is stretched
* lines cavities that can expand greatly (e.g.: urinary bladder)
* protects underlying structures, like the urinary bladder, from the caustic effects of urine

Free Cell Surfaces

* most epithelia have a ? that is not in contact w/ other cells and faces away from underlying tissues
* characteristics reflect its functions
* can be __smooth__ or lined w/ __microvilli or cilia__

Cilia

* moves materials over the top of the cell
* not stationary and can move, which allows them to remove mucus that contains foreign particles from the respiratory airways
* Mucus is moved toward the throat → swallowed → acid in stomach degrades foreign particles 
* Found on the free surfaces of Simple Columnar Epi cells of the uterus and uterine tubes, where cilia help move mucus and oocytes (eggs)


* Pag may ?, laging may mucus
* Respiratory is prone to microorganisms kase we constantly breathe kaya built sya with respiratory tract and ? exists lagi sa respiratory

Microvilli

* increases surface area
* stationary and found in cells that absorb or secrete
* ex: lining of small intestine

Cell Connections

* cells have several structures that hold one cell to one another or to the basement membrane
* desmosomes, hemidesmosomes, tight junctions

mechanically bind the cell together, form permeability barrier, provide mechanism for intercellular communication

3 things that the structures of cell do

Desmosomes

* mechanical links that bind cells together
* found in epi tissues subjected to mechanical stress like Stratified Squamous Epithelium (STRATSE) of skin

Hemidesmosomes

anchor cells to the basement membrane

Tight Junctions

* prevents the passage of materials bet. epi cells
* completely surround each cell
* found in the lining of the intestines
* form barriers and anchor cells to each other
* form a barrier to the mvmt of ions bet. epi cells

Adhesion belts

\
* Found below the tight junctions and help TJ anchor the epi cells together
* Provides additional strength for the binding of cells together at locations of TJs

Gap Junctions

* Cell connection structures that allow for intercellular communication


* small channels that allow small mols and ions to pass from one epi cell to an adjacent one
* Most epithelial cells are connected to each other by ?, and researchers believe that mols or ions moving thru the ? act as **communication signals** to coordinate the activities of the cell
* ? bet. cells of ciliated epithelial tissue may coordinate mvmt of the cilia
* In cardiac and smooth muscle, electrical signals are passed from cell to cell thru GJ, which allows for coordinated contraction

Glands

* Composed of epithelium supported by a network of connective tissue


* Specialized secretory organs
* Secrete substances onto a surface, into a cavity, or into the bloodstream
* Both glands and its ducts are lined with epithelium

Exocrine Glands

• glands w/ ducts (may tubes)

• mostly multicellular

• some are composed of single cell, like goblet cells, that secrete mucus

• can be classified acc to the structure of their ducts and secretory regions

• produce a wide variety of products such as saliva, sweat, and digestive tract secretions

• Secretions enter ducts, which are continuous w/ epi tissue surface → at the appropriate location, they exit onto the free surface of the target organ’s tissue

• Categorized based on their structure, separated based on their mode of secretion

• 3 specific distinctions: structure of duct, structure of the secretory portion of the gland, mode of secretion w/in the secretory portion

Endocrine Glands

* ductless glands
* secrete products (hormones) into the bloodstream
* Associated w/ an extensive network of blood vessels and their hormones are transported throughout the body by way of the blood

Simple Glands

single, non-branched duct, some have branced ducts (e.g: sweat glands)

Compound Glands

have multiple, branched ducts (e.g: mammary glands)

Tubular

glands w/ secretory regions shaped as tubules (small tubes)

Acinar or Alveolar

glands with secretory regions shaped in saclike structures

coiled

Tubular glands can be straight or ?

Tubuloacinar or Tubuloalveolar

glands with a combination of the two types of glands based on the shape of their secretory regions

Merocrine Secretion

* release of secretory products by exocytosis
* ex: sweat, and salivary glands

Apocrine Secretion

* release of secretory products as pinched-off fragments of the gland cells
* ex: mammary gland

Holocrine Secretion

* shedding of entire cells
* ex: sebaceous gland

Connective Tissue

* makes up part of every organ in the body
* consists of cells separated from each other by abundant extracellular matrix
* diverse in structure and function

cells, protein fibers, extracellular matrix

connective tissue is composed of ?, ?, and ?

enclosing and separating other tissues

* function of connective tissue
* form capsules around organs such as liver and kidneys
* forms layer that separate tissues and organs
* ex: separates muscles, arteries, veins, and nerves from one another

Connecting tissue from one another

* function of connective tissue
* tendons and ligaments

Tendon

strong cables, or bands of connective tissue that attach muscles to bone

Ligaments

connective tissue bands that hold bones together

supporting and moving parts of the body

* function of connective tissue
* bones = provide rigid support for the body
* semirigid cartilage = supports structures such as the nose, ears, and surface of joints
* joints = allow one part of the body to move relative to other parts

Storing compounds

* function of connective tissue
* Adipose (fat) tissues = stores high-energy molecules


* Bones = store other minerals kase d pwede marupok such as calcium and phosphate Adipose tissue/ fat cells store energy

cushioning and insulating

* function of connective tissue
* Adipose tissue ? and protects the tissues it surrounds
* provides an ? layer beneath the skin that helps conserve heat
* Mammary gland


* Preserve thermal energy

transporting

* function of connective tissue
* Blood = transports nutrients, gases, enzymes, hormones Transports nutrients oxygen 


* Through Blood 
* Waste co2

protecting

* function of connective tissue
* White blood cells


* cells of immune system and blood = against toxins and tissue injuries, and microorganisms
* bones

extracellular matrix

specialized cells of the various connective tissues produce the ?

osteoblasts

form bones

osteocytes

maintain the bones

osteoclasts

break down bones

fibroblasts

cells that form fibrous connective tissue

fibrocytes

maintain the fibrous connective tissues

chondroblasts

form cartilage

chondrocytes

maintains cartialge

immune system

found in connective tissue are cells associated w/ the ?, such as WBCs

Macrophages

large cells that are capable of **moving** abt and **ingesting** foreign substances, including microorganisms in the connective tissue

Mast cells

nonmotile cells that release chemicals, such as histamine, that promote **inflammation**

protein fibers, ground substance, fluid

extracellular matrix of connective tissue has 3 major components: ?, ?, and ?

collagen, reticular, elastic

3 types of protein fibers which help form most connective tissue

Collagen fibers

* Resemble microscopic ropes,


* Very flexible but resist stretching

Reticular fibers

\
* Very fine, shorten collagen fibers that branch to form a supporting network

Elastic fibers

Have the ability to return to their “original shape” after being stretched or compressed, giving tissue an elastic quality.

MATRIX GROUND SUBSTANCE

\
* Consists of non-fibrous protein, other molecules and is SHAPELESS.
* The structure is responsible for the functional characteristics of connective tissues
* Ex: enable bones and cartilage to bear weight.

Loose connective tissue

* type of connective tissue
* has few protein fibers


* Form a lacy network, with numerous spaces filled with ground substance and fluid.
* maraming space

Areolar

* subdivision of loose connective tissue
* Consists of collagen fibers and a few elastic fibers


* Fibroblasts

Fibroblasts

* most common cells in loose connective tissue

Adipose

* subdivision of loose connective tissue
* Consists of adipocytes, or fat cells, containing a large amount of lipid for energy storage.


* ? tissue pads and protects parts of the body
* Acts as a thermal insulator

Reticular

* subdivision of loose connective tissue
* Forms the framework of lymphatic tissue, such as in the spleen and lymph nodes, as well as in bone marrow and the liver

Dense connective tissue

* type of connective tissue
* Has a relatively large number of protein fibers that form thick bundles and fill nearly all of the extracellular space.
* 2 major subcategories: Collagenous and elastic


* Has an extracellular matrix consisting mostly of collagen fibers
* dikit-dikit, onti ang space, and masikip

Dense Regular

* Dense collagenous connective tissue having the collagen fibers oriented in the same direction is termed ?
* ex: tendons and ligaments

Dense irregular

* Dense collagenous connective tissue having the collagen fibers oriented in the multiple direction is termed ?
* ex: dermis of the skin and in organ capsules

Dense elastic connective tissue

* Has abundant elastic fibers among its collagen fibers


* Elastics fibers allow the tissue to stretch and recoil
* Ex: in the “vocal cords”
* **Marfan syndrome** 
* A genetic condition that is the inability to properly maintain and form elastic fibers.