A&P Ch.4 Tissues

Tissues

any grouping of cells that are similar in structure and carry out similar or common functions

Four Primary Types of Tissues

1. Nervous tissue

2. Muscle Tissue

3. Epithelilal Tissue

4. Connective Tissue

Nervous Tissue

control tissue: regulates and controls various body functions, brain, spinal cord, and nerves

Cell Types of Nervous Tissue

1. Neurons- creating/transmitting electrical impulses through entire body + can respond to various stimuli

2. Supporting Cells- protect, insulate, and support neurons

Which Tissue?

Nervous Tissue

Muscle Tissue

movement tissue, allows for mobility (voluntary and involuntary), well innervated

Skeletal Muscle Tissue

voluntary control with striations- attach to bones and use bones to produce movement, multi nucleic

what tissue?

Skeletal Muscle tissue

Cardiac Muscle Tissue

involuntary control with striations, found only in walls of the heart, singular nucleus per cell

what tissue?

cardiac muscle tissue

Smooth Muscle Tissue

involuntary control without striations, found in walls of hollow organs, singular nucleus per cell

what tissue?

smooth muscle tissue

Covering Epithelium

forms the covering of all internal and external surfaces of the body, lines body cavities, and hollow organs

Cutaneous membrane

covering epithelium- skin/dry epithelial layer

Mucous membrane

epithelial that lines a body cavity that leads directly to inside/outside of the body (inside of mouth)

Serosa

epithelial covers pleura, pericardium, peritoneum, and internal organs

Glandular Epithelium

makes up exocrine glands of body

Apical Surface

the exposed side of epithelial cells, faces the lumen of hollow organs or the outside of the body

many have microvilli- increase surface area

some have cilia- propel substances through space

Basal Surface

attaches epithelial cells to underlying tissue, prevents too much movement but allows if needed

Contact between neighboring Epithelial cells

joined by tight junctions or desmosomes (forms sheets)- only for covering epithelium

Basement Membrane

defines boundary between epithelia and underlying connective tissue- attached to basal surface

Characteristics of Epithelial Tissue

1. Avascular- no blood supply, receive O2 and nutrients and dispose of waste by diffusion

2. Innervated- supplied with nerve fibers

3. High capacity for regeneration- subjected to high levels of abrasion and hostile conditions, easily replaced cells, prevents loss of function for epithelial

Simple Layer Epithelia

contains only one layer of cells- all cells are in contact with basement membrane

Stratified Layer Epithelia

contains 2+ layers of cells, only deepest layer is attached to basement membrane, rest is held together by tight junctions and desmosomes

Squamous Epithelial Cells

squished shape, kinda circular, flattened

Cuboidal Epithelial Cells

cube shaped

Columnar Epithelial Cells

long, rectangular cells, like a column

Functions of Simple Epithelia

1. Absorption

2. Filtration

3. Secretion

Simple Squamous Epithelium- + types

exceptionally thin and permeable

1. Mesothelium- epithelium of pleura, pericardium, and peritoneum (serous membranes)

2. Endothelium- forms slick/slippery linings of blood vessels

Pseudostratified Columnar Epithelium

“false stratified” because overlapping of one layer makes it look multilayered, but all cells touch the basement membrane

Absorption

the process of taking substances into a cell across a tissue or organ (ex: nutrients)

Filtration

the passing of a fluid through a filter to remove waste, toxins, or unneeded substances (ex: kidneys)

Secretion

a process where substances are produced and released by a cell or a gland for a function (ex: sweat glands)

Stratified Epithelial Function

protection from abrasion/friction-resistance

Stratified Squamous Epithelium

most common, skin, forms a protective barrier, basal cells almost constantly reproducing (mitotically active), apical cells poorly nourished (diffusion can only go so far),- usually already dead or rubbed off

Stratified Cuboidal and Columnar Epithelia

rare, usually just two layers, more layers could be too thick to function

can be found in sweat glands, mammary glands, and certain parts of male reproductive system

Transitional Epithelium (Urothelium)

basal cells are mostly cuboidal/columnar, apical cell shape varies

stratified-looks like a mess

only found in urinary system-cells are good at stretching and going back to o.g. shape, so for the bladder

Glands

one or more cells that produce and release a particular product

Exocrine Glands

secretions released onto surfaces or into cavities

Endocrine Glands

just for the secretion of hormones, enter blood

Merocrine Glands

mode of secretion of exocrine glands- secretion release by exocytosis, cell remains unchanged

Holocrine Glands

mode of secretion of exocrine glands- oil glands, secretion is released due to complete cell rupture

Apocrine Glands

mode of secretion of exocrine glands- like holocrine, but cells do not completely rupture, like a corner tearing off

Connective Tissue -Functions

most abundant and widespread of all tissues

major functions- protection, support, insulation, storage

Characteristics of all Connective Tissue

1. Extracellular Matrix- nonliving, ground substance+fibers

2. Origin- arises from mesenchyme- embryonic tissue

Three Components of Connective Tissues

1. Ground Substance

2. Fibers

3. Cells

Ground Substance+ what’s in it

fills space surrounding cells +contains fibers

• interstitial fluid: allows passage between blood and cells

• cell adhesion proteins: proteins acting like “glue” to hold living cells to ECM

• Proteoglycans: proteins that give ground substance its consistency, when binds to water- more firm GS

Fibers

supportive structure of connective tissue, hold tissue together, prevent from tearing

Collagen Fibers

produces protein collagen, assemble and cross link with other collagen fibers

strong and flexible to resist pulling forces-tensile strength

skin

Elastic Fibers

contains protein elastin, easily stretched and will return to normal shape, high density in areas of body that are subjected to frequent stretching

lungs

Reticular Fibers

thick like collagen, but shorter

extensively branched to form fine networks, like mesh/fishnet

Cells in connective tissue

cells found in connective tissues can be immature (-blast) or mature (-cyte)

-blast cells

lay down ground substance +fibers

immature bone cell

-cyte cells

monitor and maintain ground substance and fibers

mature, monitors -blasts activity

Four Types of Connective Tissue

1. Connective Tissue Proper

2. Cartilage

3. Osseous (bone)

4. Blood

Areolar Connective Tissue

type of loose connective tissue (proper)

chief cell type is fibroblasts- produce collagen fibers

supports/binds, nourishes, defends, stores, holds body parts together

found almost everywhere

Adipose Connective Tissue

type of loose connective tissue (proper)

chief cell type is adipocyte

easy to access energy source- high metabolic activity

mostly subcataneous, but can be found wherever areolar tissue is

Reticular Connective Tissue

type of loose connective tissue (proper)

composed of reticular fibers

forms stroma to support free blood cells in lymph nodes, spleen, and bone marrow

Connective Tissue Proper

any connective tissue that is not bone, cartilage, or blood

loose connective tissue and dense connective tissue, elastic

Dense Connective Tissue (general)

tough, fibrous tissue packed with collagen fibers → high tensile strength + structural support to the body

dense regular and dense irregular

Dense Regular Connective Tissue

type of dense connective tissue (proper)

chief cell type is fibroblast

collagen fibers (lots) run in the same direction

high resistance to tension

in tendons and ligaments

Dense Irregular Connective Tissue

type of dense connective tissue (proper)

collagen fibers run in different directions - resistant to pulling in different directions

high resistance to tension

skin

Elastic Connective Tissue (proper)

have elastic fibers, very elastic, tissue recoils easily after stretching

lungs

Cartilage

type of connective tissue

chief cell types are chondroblasts and chondrocytes

flexible, but tough

avascular and no innervation- hard to heal

Hyaline, Elastic, Fibrocartilage

Osseous Tissue (Bone)

type of connective tissue

chief cell types are osteoblasts and osteocytes

found in bone (large number of collagen fibers)

tissue contains inorganic calcium salts that makes it rigid-bone salts deposited on fibers

highly vascularized and innervated

Blood

the only fluid connective tissue

cell types: erythrocytes (RBC), leukocytes (WBC), and thrombocytes (blood platelets)

fibers only form during blood clotting

functions: transport (hormones, O2, CO2, nutrients, ions), regulation of body temp, protection, homeostasis (stops bleeding)

Tissue Regeneration

what happens for simple injury- overruling, stretching

damaged tissue scraped away, replaced with new (stratified squamous)

Fibrosis

what happens when a larger injury occurs, ex: scraped skin

Step 1 of Fibrosis

injury occurs

• severe blood vessels will bleed

• blood clot forms at damaged site, surface of clot dries to form a scab

• surrounding undamaged blood vessels become more permeable, to get what it needs for repair

Step 2 of Fibrosis

restoring blood supply and initiating scar tissue formation

blood clot found underneath scab replaced by granulation tissue

blood supply from granulation tissue brings in important cell types

• fibroblasts (collagen-scar) lay down new fibers to seal the wound

• microphages phagocytize dead and dying cells, dirt and debris, and anything that may cause infection

• epithelial cells will reproduce to replace lost cells at surface of injury

Step 3 of Fibrosis

completion of regeneration and fibrosis

• fibroses area matures and thickens (more fibers laid down)

• epithelium continues to regenerate-fibrose area may or may not be visible

• when epithelium is completely regenerated → scab detaches and falls off