Human Anatomy Chapter 4- Tissues

3. Desmosomes

(anchoring junctions) 1. the main junction for binding cells together 2. two disc like plaques connected across intercellular space 3. plaques of adjoining cells are joined by proteins called cadheins 4. proteins intedigiate into extracellular space 5. intermediate filaments insert into plaques from cytoplasmic side zipper gives a lot of strength

1. tight junctions

(zonula occludens) 1. a belt like junction that entends around periphery (apical region) 2. closes off extracellular space 3. some proteins in plasma membrane of adjacent cells are fused preventing molecules from passing between cells of epithelial tissue (buttons) (small dots on the right side) - find these between epithelial cells *

What are epithelial cells highly specialized to do?

-remove materials from the blood and to manufacture them into new materials which they secrete

Exocrine glands

-retain their ducts, and their secretion empty through these ducts to an epithelial surface (skin or body cavities) - local activity: diverse group of cells (a lot of cells in ducts) e.g. sweat glands

Unique characteristics of Epithelia

1. Cellularity- composed almost entirely of cells -mostly just cells 2. Special contacts- form continuous sheets held together by tight junctions and desmosomes - how cells stick together) surfaces 3. Polarity- apical (upper free) and basal (lower attac 4. Supported by connective tissue- reticular and basal laminae (basement membrane) -north and south -deep to epithelium 5. Avascular but innervated- no vessels, has nerves 6. High regenerative capacity- rapidly replaces lost cells by cell division -grows all the time

What are the 4 simple structural plans of connective tissue?

1. Embryonic origin 2. rich supply of blood vessels 3. many cell types 4. extracellular matrix

Special Types- Simple squamous epithelium

1. Endothelium (inner covering)- slick lining of hollow organs 2. Mesothelium (middle covering)- lines peritoneal, pleural, and pericardial caviites, covers visceral organs and those cavities

Extracellular matrix has two structural components

1. Ground substance 2. Fibers

Location- simple columnar epithelium

1. Nonciliated form- lines digestive tract, glallbladder, ducts of some glands 2. Cilated form- lines small bronchi, fallopian tubes, uterus (the ones we look at wont have cilia)

Location- stratified columnar epithelium

1. Rarest tissue type, found in male urethra and large ducts of some glands

Function- Pseudostratified Ciloated Columnar Epithelium

1. Secretion of mucus, propulsion of mucus by cilia

Glands are classified by?

1. The site of release: Endocrine (Internally releasing) vs. Exocrine (externally releasing) 2. The relative number of cells forming the gland -Unicellular or Multicellular

Function- simple columnar epithelium

1. absorption 2. secretion of mucus 3. ion transport 4. ciliated type propels mucus or reproductive cells by ciliary action

Functions- basal lamina

1. acts as a selectibe filter, determining which molecules from capillaries enter the epithelium -2. acts as scaffolding along which regenerating epithelial cells can migrate

Lateral surface feature- Three factors act to bind epithelial cells to one another

1. adhesion proteins- in the plasma membrane link together adjacent cells 2. the wavy contours of the membranes of adjacent cells (tongue and grooves) 3. special cell junctions

2. Adhesive junctions

1. adhesive belt junctions 2. an anchoring junction just below tight junction 3. transmembrane linker protein attach to actin microfilaments of the cytoskeleton and bind adjacent cells 4. with tight junctions form the tight junctional complex around the apical lateral border of epithelial tissues -creates another tight junction

Epithelia are classified according to two criteria

1. arrangement- or relative number of layers (first name of tissue) 2. cell shape (last name of tissue)

Four main types of adult connective tissue

1. connective tissue proper- fat tissue and fibrous tissue of ligaments 2. cartilage 3. bone tissue 4. blood

What are the four major categories of tissues?

1. epithelial tissues (epithelium)- sheet of cells covering body surface or lining a body cavity 2. connective tissue- includes c.t. proper (fat and ligaments) cartilage, bone, and blood, provides support 3. nervous tissue- main component of the nervous system provides control 4. muscle tissue- includes skeletal, cardiac, and smooth muscle, provides movement

Location- stratifed cuboidal epithelium

1. forms largest ducts of SWEAT GLANDS 2. forms ducts of mammary glands 3. salivary glands (typically glands)

Location- simple cuboidal epithelium

1. kidney tubules 2. secretory portions of small glands 3. ovary surface

Location- transitional epithelium

1. lines the ureters 2. urinary bladder * 3. part of urethra (all stretch)

Functions- Connective tissue

1. protect 2. support (cartilage and bone) 3. bind together (tendons and ligaments) other tissues of the body

What are the functions of epithelia

1. protection 2. absorption 3. filtration 4. secretion 5. diffusion 6. sensory reception

Function- stratified columnar epithelium

1. protection 2. secretion (coming out, not coming in)

Function- stratified squamous epithelium

1. protection- underlying tissues in areas subject to abrasion

2 other types of epithelia

1. pseudostratified epithelium - actually a simple columnar epithelium one layer of cells, but because its cells vary in height and the nuceli lie at different levels above the basement membrane it gives a false appearance of being stratified. (this epithelium is often ciliated) 2. Transitional epithelium -Stratified squamous epithelium are formed of rounded or plump cells with the ability to slide over one another to allow the organ to be stretched. ONLY found in urinary systems e.g. bladder

Location- Simple squamous epithelium

1. renal corpuscles 2. alveoli of lungs 3. lining of heart, blood and lymphatic vessels and ventral body cavity (serosae)

Function- simple cuboidal epithelium

1. secretion 2. absorption

Arrangement of epithelia

1. simple: consisting of one layer of cells attached to the basement membrane 2. stratified: consisting of two or more layers of cells

Types of epithelia- cell shape

1. squamous- cells wider than tall (plate like) 2. cuboidal- cells are as wide as tall (cube like) 3. columnar- cells are taller than they are wide (column like)

Function- transitional epithelium

1. stretching 2. permits distension of urinary bladder causing thinning 3. BLADDER that will stretch

4 types of cell junctions

1. tight junctions 2. adherens junctions 3. desmosomes 4. gap junctions (nexus)

4. Gap junction (nexus)

1. tunnel like passageway between two adjacent cells (anywhere) 2. let small molecules move directly between neighboring cells 3. cells are connected by hollow cylinders of protein (connexons) -acts as communicators * - sends each other ions or sends hormones -gaps allow cell to cell communication -located at basal surface of epithelium

Glands are also classified ____ and ____

1. unicellular 2. multicellular

Examples of some Connective Tissue

1.Osseous tissue- connective tissue of bones 2.Areolar connective tissue- soft packaging material that cushions and protects body organs 3. Adipose (fat) tissue- provides insulation of the body tissues and a source of stored food 4. Hematopoietic tissue- replenished the body's supply of red blood cells

What makes up the basement membrane?

Basal surfaces + fibers

Every fluid is a filtrate from?

Blood (glands get fluid from blood)

3. Many cell types

Connective tissues are composed of many cell types but relatively few cells - big variety but few cells in them

How does epithelium get nutrients from the capillaries?

Diffuse through basement membrane. it is selectively permeable

What is the difference in speed with endocrine and exocrine glands?

Endocrine- typically releases hormones which travel far Exocrine- very short distance

Glands develop from__

Epithelial membrane

The ___ ___ distinguishes connective tissue from all other tissues

Extracellular matrix

Endocrine sends product __

Far! the organs may not be right next to it

2. Rich supply of blood vessels

Generally, connective tissues have a rich supply of blood vessels. (vascularized) exceptions include- cartilage, tendons and ligaments (avascular)

Single celled exocine gland

Goblet cell

What is a single celled gland?

Goblet cell

What component of the extracellular matrix hold the intersitial fluid?

Ground substance

4. Extracellular matrix

In between the cells of connective tissue are a vast amount of noncellular (non living material) called extracellular matrix

Location- stratified squamous epithelium

Keratinized forms- epidermis (hardened cells) Non-keratinized forms- lining of esophagus, mouth and vagina (mucus membrane) - no fluid moving across -main function of stratified is protection

Exocrine sends product___

NOT far. at a very short distance e.g. sweat on the surface of the skin

Location- Pseudostratified Ciliated Columnar Epithelium

Non-ciliated form- is in ducts of male reproductive tubes and ducts of large glands Ciliated form- lines the TRACHEA and most upper respiratory tract

Function- Simple squamous epithelium

Passage of materials by passive diffusion and filtration and secretes lubricating substances in seorsae (membranes) -expect things to pass through it such as gases

Function- stratified cuboidal epithelium

Protection

2. Fibers

Provide support. ex. collagen fibers, elastic fibers, reticular fibers all made from a single cell called fibroblast

What type of epithelia is always ciliated?

Pseudostratified Ciliated Columnar Epithelium (technically only has one layer)

1. Ground substance

The ground substance functions as the MEDIUM through which nutrients and other dissolved subtances can diffuse between the blood capillaries and cells -Holds the INTERSTITIAL FLUID (fluid component of the connective tissue)

What type of epithelia is only found in the urinary system?

Transitional. the shape at the top is domed because it stretches.

True or False: There is nothing between epithelia?

True. Nothing between epithelia, but connective tissue is very spread out

Do all connective tissues share the same simple structural plan?

Yes

1. Simple squamous epithelium

a single layer of flat cells with disc shaped nuclei and sparse cytoplasm

Stratified epithelia are named

according to the cells at the apical surface of the epithelial membrane, not those resting on the basement membrane

4. Pseudostratified Ciliated Columnar Epithelium

all cells originate at basement membrane. only tall cells reach the apical surface; may contain goblet cells and bear cilia; nuceli lie at varying heights within cells (gives false impression of statification)

1. Embryonic origin

all types of CT originate from the embryonic tissue called mesenchyme

The products of the gland are ___

aqueous fluids that usually contain a protein

Epithelium is ___ but ___

avascular but innervated

4. Transitional epithelium

basal cells usually cuboidal or columnar, superficial cells dome-shaped or squamous, undergoes transitions in shape

Doublet

each paif of microtubules arrange in a doublet

Glands derived from ____ tissue

epithelial

Basal lamina is where the?

epithelium meets the connective tissue

Other motile appendages: Flagella

extremely long cilia used to propel cells/ organisms

All fibers are made from a single cell called

fibroblast

Apical surface features- Microvilli

finger-like extensions of plasma membrane -maximizes surface area across which small molecules enter or leave (creates waves to increase surface area) -abundant in epithelia of small intestine and kidney

2. Multicellular

formed by invaginations or evaginations and usually have ducts (tube-like connections to epithelial sheets) that carry products of exocrine glads to epithelial surface e.g. salivary glands

2. Connective Tissue

found in all parts of the body as discrete structures or as part of various body organs

The structure of epithelium reflects its ___

function

2. Stratified cuboidal epithelium

generally two layers of cubed shaped cells

Epithelia: Gland

gland- many epithelia cells that make and secrete a product

Tissues

groups of closely associated cells that perform related functions and are similar in structure

What are cilia?

hair like projections that move mucus out.

Endocrine glands secrete

hormones directly into the blood or the lymphatic vessels (tissue fluid) that weave through the glands to specific target organs far from the site of release

Movement of cilia

in coordinated waves. pushes itself like a wip stands up and recoils

Epithelia occurs at the ___

interfaces between two different environments

Endocrine glands

lose their surface connection (duct) as they develop. this they are referred to as "ductless glands" -when they release product it goes into the blood stream

2. Stratified Squamous Epithelium

many layers of cells, superficial layers are squamous on shape while deeper layers of cells appear cuboidal or columnar, thickest epithelial tissue, adapted for protection

Goblet cells produce __

mucin which is a a glycoprotein that dissolves in H20 to become slimy, covers and protects and lubricates many internal body surfaces e.g. trachea mucus grabs, cilia pushes out

Mucin + water =

mucus

To perform specific functions the tissues are organized into ___

organs. such as stomach, heart, kidney, and lungs

Unicellular exocrine gland (goblet cell)

scattered throughout epithelial lining intestines and respiratory tubes between columnar cells

1. Unicellular

scattered within epithelial sheets e.g. goblet cells

3. Stratified columnar epithelium

serveral layers; basal cells usually cuboidal; superficial cells elongated

3. Simple columnar epithelium

single layer of column shaped (rectangular) cells with oval nuclei, some bear cilia at their apical surface, may contain golbet (mucus secreting) cells (absorption taking place)

2. Simple cuboidal epithelium

single layer of cube like cells with large, spherical central nuceli

why do we want epithelial tissue tight?

so that bacteria will not slip through them

Example of flagella

sperm - sperm is the only cell that has flagellum in our bodies

Basal lamina and reticular fibers of the underlying connective tissue deep to it form

the basement membrane

Basal surface feature- Basal lamina

the border between the epithelia and the underlying C.T. - Non-cellular supporting sheet of proteins secreted by epithelial cells

1. Epithelia and Glands- Epithelia

the tissues that cover the external body surface (epidermis) lines its cavities and tubules and generally "marks off our inside from our outsides"

Movement of flagella

whip like pattern - like a propeller causing a current

Apical surface feature- Cilia

whip like, high motile extensions of apical surface membranes -contains a core of microtubules, each pair of microtubules arranges in a doublet