Chapter 4 Histology

There are 50 trillion cells of 200 different cell types. True or False?

True

histology

study of normal structures of tissues

tissues

group of structurally and functionally related cells and their external environment

All tissues share ____ basic components.

two

Tissues consist of discrete population of _____ that are related in structure and function.

cells

Tissues have a surrounding non-living material called extracellular _____.

matrix

epithelial tissues

tightly packed sheets of cells with no visible extracellular matrix

Epithelial tissues cover and line all body surfaces and _______.

cavities

Epithelial tissues have specilized epithelia that form _____ that manufacture secretions like sweat, saliva, or chemical messengers.

glands

connective tissues

connects all other tissues to one another

________ is a prominent feature for most connective tissue types with cells scattered throughout.

Extracellular matrix

What is the function of connective tissues?

bind, support, protect, and allow for transportation of substances

muscle tissues

elongated cells capable of generating force by contracting

nervous tissues

capable of generating, sending, and receiving messages

neurons

cells that support this activity also within a unique ECM

extracellular matrix

composed of substances in a liquid, thick gel, or solid that surround cells of a tissue

The ECM is made up of _________ and __________.

ground substance and protein fibers

ground substance

a gel-like material that fills the spaces between cells and fibers

The ECM provides tissue with ________ to resist stretching and compressive forces.

strength

The ECM _______ cells to their proper positions within a tissue and holds those cells in place.

directs

The ECM __________ development mitotic activity, and survival of cells in a tissue.

regulates

Ground substance makes up most of the ECM and consists of extracellular fluid (ECF or interstitial fluid). True or False?

True

What is the ECM made of?

water, nutrients, ions, and three families of macromolecules

glycosamingoglycans

examples are chondroitin sulfate and hyaluronic acid

Negative charges of certain sugars in a glycosaminoglycan attract _________ charged ions in extracellular fluid.

positively

lons create concentration gradient within extracellular fluid, draws water _____ cells and blood vessels by osmosis. (out/in)

out

proteoglycans

glycosaminoglycans bound to a protein core

Thousands of __________ bind to a very long glycosaminoglycans such as hyaluronic acid, forming huge proteoglycan "aggregates".

proteoglycan

Proteoglycans help make ECM firmer, more solid, and resistant to _________.

compression

aggregates

form barrier to diffusion of substances through ECM; protects underlying tissue from invading microorganisms

Cell-adhesion molecules

made up of different types of glycoproteins

Cell-adhesion molecules adhere cell to cell and cells to surroundings; hold everything in place within ECM. True or False?

True

Cell-adhesion molecules bind to cell ____________ as well as protein fibers and proteoglycans; maintain normal tissue architecture.

surface proteins

protein fibers

embedded within ground substance as long molecules composed of multiple fibrous subunits with a ropelike structure for enormous tensile strength

collagen fibers

make up 20-25% of all proteins in the body

What are collagen fibers made of?

multiple repeating subunits that form a white fibrous protein

What is the function of collagen fibers?

they are resistant to tension and pressure

elastic fibers

composed of protein elastin surrounded by glycoproteins

Elastic fibers extensibility allows the fiber to _______ up to one and a half times resting length without breaking.

stretch

Once elastic fibers are stretched, fibers return to resting length. True or False?

True

reticular fibers

thin, short collagen fibers

What is the structure of reticular fibers?

they form a web-like structure, meshwork, or scaffold

What is the function of reticular fibers?

supports cells and ground substance of many tissue and is in the spleen and lymph nodes to help trap foreign cells

cell junctions

another way cells connect and bind to one another where neighboring cell's plasma membranes are linked by integral proteins

tight junctions

hold cells closely together such that space between is impermeable to movement of macromolecules

What is the function of tight proteins?

integral proteins of adjacent cells' plasma membranes are locked together forming a seal

around the apical perimeter of the cell

desmosomes

composed of linking integral proteins; allow for materials in extracellular fluid to pass

through space between cells

Desmosomes increase strength of a tissue by holding cells together so mechanical stress is more evenly distributed. True or False?

True

Where are desmosomes found?

in tissues subjected to a great deal of mechanical stress such as epithelia of skin (peeling) and the heart

gap junctions

small pores formed by protein channels between adjacent cels that allow small substances to flow freely between each cells cytoplasm

Where are gap junctions found?

in between cells that communicate with electrical signals such as cardiac muscle cells