tissues of the body - bowen university

Tissues of the bodyANA 209

Histology: The Study of Tissues

2

Tissues and Histology

Tissue Level of Organization

Epithelial

Connective

Muscle

Nervous

Histology: Microscopic Study of Tissues

3

Epithelial Tissue

Protective covering of surfaces, both

outside and inside the body.

Consist of cells with little extracellular

material between them.

Cover surfaces of the body and form

glands that are derived

developmentally from body surfaces.

4

Epithelial TissueOne free surface not attached to other cells

Lateral surface, attached to other epithelial

cells

Basal surface attached to basement

membraneBasement membrane- specialized type of extracellular material

secreted by epithelial cells (glycoproteins) and connective tissue

cells which help to attach epithelial cells to the underlying tissue

5

Epithelium Characteristics

Consists almost entirely

of cells

Covers body surfaces

and forms glands

Has free and basal

surface

Specialized cell

contacts

Avascular

Undergoes mitosis

6

Functions of Epithelia

Protecting underlying structures

Acting as barriers

Permitting the passage of substances

Secreting substances

Absorbing substances

7

Classification of Epithelium

Simple

Squamous, cuboidal, columnar

Stratified

Squamous, cuboidal, columnar

Pseudostratified

Columnar

Transitional

Cuboidal to columnar when not stretched and

squamouslike when stretched

8


Simple- consists of a single layer of cells, with each layer extending from basement membrane to free surface

Squamous, cuboidal, columnar (w/ or w/o microvilli)

Squamous- flat or scale-like

Cuboidal- cube shaped, as wide as tall

Columnar- tall and thin, taller than wide

9

Types of Epithelium10


Stratified- consists of more than one layer

of cells, only one of which is attached to

the basement membrane

Squamous (wet and dry), Cuboidal,

Columnar

13


Pseudostratified- single layer of cells;

some tall and thin and reach the free

surface while others do not

Nucleii of these cells are at different

levels and appear stratified

Cells are almost always ciliated and

are associated with goblet cells that

secrete mucus onto the free surface

17


Transitional- stratified cells that appear

cuboidal when the organ or tube is

not stretched, and squamous when

the organ or tube is stretched by fluid

19

Epithelial Tissue

Epithelial cells retain the ability to undergo mitosis

and therefore can replace damaged cells with

new ones

Undifferentiated cells (stem cells) continuously

divide and produce new cells. In some types

of epithelia, such as skin and digestive tract,

cells that are lost or die are continuously

replaced by new ones.

21

Epithelial Tissue

Specialized cell contacts, tight junction and

desmosomes, bind adjacent epithelial cells together

Blood vessels don’t penetrate basement membrane to

reach epithelium

All nutrients and gasses carried in the blood must reach

via diffusion across the basement membrane

22

Cell Connections

Functions

Bind cells together

Form permeability

layer

Intercellular

communication

Types

Desmosomes

Tight

Gap

23

Functional Characteristics

Cell layers and shapes Diffusion, Filtration, Secretion, Absorption, Protection

Cell surfaces Microvilli: Increase surface area absorption or secretion

Cilia: Move materials across cell surface

Cell connections Desmosomes, tight, gap

Glands Exocrine: Have ducts

Endocrine: Have no ducts

24

Glands

Secretory organs

Composed primarily of epithelium with a supporting network of connective tissue

Glands with ducts are termed exocrine

Glands without ducts are termed endocrine

Cellular products of endocrine glands are hormones

25

Exocrine Glands

Unicellular

Goblet

cells

26

Multicellular Exocrine Glands27

Exocrine Glands and Secretion

Types

Merocrine

Sweat glands

Apocrine

Mammary

glands

Holocrine

Sebaceous

glands

28

Connective Tissue

Abundant

Consists of cell separated by extracellular

matrix

Diverse

Performs variety of important functions

29

Functions of Connective

TissueEnclosing and separating as capsules around

organs

Connecting tissues to one another as tendons

and ligaments

Supporting and moving as bones

Storing as fat

Cushioning and insulating as fat

Transporting as blood

Protecting as cells of the immune system

30

Connective Tissue Cells

Specialized cells produce the

extracellular matrix

Suffixes

-blasts: create the matrix

-cytes: maintain the matrix

-clasts: break the matrix down for

remodeling

31

Extracellular Matrix

Components

Protein fibersCollagen which is most common protein in body

Reticular fill spaces between tissues and organs

Elastic returns to its original shape after distension or compression

Ground substanceShapeless background

Fluid

32

Collagen Fibers

Strong and flexible but inelastic

Many types (at least 20)

33

Reticular Fibers

Very fine collagen fibers

Very short and thin

Branch to form networks

Not as strong as most collagen fibers

34

Elastic Fibers

Contain a protein called elastin

Has the ability to return to original shape

35

Other Matrix

MoleculesGround substance

Consists of hyaluronic acid, gives a slippery

quality to fluid

Good lubricant for joint cavities

Proteoglycans trap large quantities of H2O

which give them the ability to return to

original shape

Adhesive molecules

36

The structure of the matrix gives connective tissue types most of

their functional characteristics.

Bone and cartilage

wt bearing

Tendons and ligaments

withstand stress

Dermis of skin

Withstand damage

37

Loose Connective Tissue

Also known as areolar tissue

Loose packing material of most organs and tissues

Attaches skin to underlying tissues

Contains collagen, reticular, elastic fibers and variety of

cells 38

Dense Connective Tissue

Form thick bundles and fill nearly all of the extracellular space

Most of the cells of developing dense connective tissue are spindle

shaped fibroblasts

Dense connective tissue can be subdivided into 2 major groups

Regular

Irregular

39

Regular Dense Connective

Tissue Has protein fibers in the extracellular matrix that are oriented

predominantly in one direction

Has abundant collagen fibers which give it a white appearance

These tissues form structures such as tendons and ligaments

Resist stretching and give strength in direction of fibers

Examples are tendons and ligaments

40

Dense Regular Connective Tissue41

Irregular Dense

Contains protein fibers arranged as a mesh work of randomly oriented fibers

Alternately the fibers within a given layer can be oriented in one direction whereas the fibers of adjacent areas are oriented at nearly right angles of that layer

Sheets of connective tissue are formed that have strength in many directions

Examples are the dermis of the skin and the connective tissue capsules surrounding organs

42

Irregular Dense Elastic

In addition to collagen fibers

oriented in many directions,

there are abundant elastic fibers

in the layers of this tissue

Examples are found in the walls

of elastic arteries

43

Dense Irregular Collagenous, and

Elastic44

Connective Tissue with Special

Properties Adipose tissue

Consists of adipocytes

Types

Yellow (white)

most abundant, white at birth and yellows with

age

Brown

found only in specific areas of body as axillae,

neck and near kidneys

Reticular tissue

Forms framework of lymphatic tissue

Characterized by network of fibers and cells

45

Adipose Tissue Consists of adipocytes or fat cells, which contain large amounts of

lipids

Unlike other connective tissue types, adipose is composed of large cells and a small amount of extracellular matrix that consists of loosely arranged collagen and reticular fibers with some scattered elastic fibers

This tissue is found in the subcutaneous areas, renal pelvis, around kidneys, attached to surface of colon, mammary glands, and in loose connective tissue.

It serves to insulate and protect, as well as to provide for energy storage

46

Adipose Tissue47

Hemopoietic tissue/ blood

Abundant extracellular matrix

Free moving cells in a liquid matrix

This allows for rapid movement throughout the body

Most of the matrix is produced in cells contained in other tissues rather than blood cells

Found mostly in bone marrow

Two types of bone marrow

Yellow and red

48

Blood

Matrix between the

cells is liquid

Hemopoietic tissue

Forms blood cells

Found in bone marrow

Yellow

Red

49

Bone Marrow50

Reticular Tissue

Forms the framework of lymphatic tissue such as in the spleen and

lymph nodes, as well as bone marrow and liver

Characterized by a network of reticular fibers and reticular cells

Reticular cells produce the reticular fibers and remain closely attached

to them.

51

Reticular Tissue52

Cartilage

Composed of cartilage cells, or chondrocytes located in spaces

called lacunae

The surface of nearly all cartilage is surrounded by a layer of dense

irregular connective tissue called the perichondrium

Cartilage cells arise from the perichondrium to secrete cartilage

matrix

Cartilage has no blood vessels or nerve except those of the perichondrium.

Hyaline cartilage has large amounts of both collagen fibers and

proteoglycans

53

Hyaline Cartilage

Large amounts of both collagen fibers and protoglycans

Collagen fibers are evenly dispersed throughout the ground

substance

In joints, quite smooth

Found in areas where strong support and flexibility are needed, such

as in the rib cage, trachea, and bronchi. Also covers areas of bones

54

Hyaline Cartilage

55

Fibrocartilage

Has more collagen fibers than proteoglycans and much thicker

bundles of collagen fibers than hyaline

Slightly compressible, very tough

Found between vertebrae and areas of body where a great deal of

pressure is applied to joints (knee, jaw, etc.)

56

Fibrocartilage

57

Elastic Cartilage

Has elastic fibers in addition to collagen and proteoglycans.

Numerous elastic fibers dispersed throughout the matrix of elastic

cartilage

Found in areas that have rigid but elastic properties, e.g. external ears

and epiglottis

58

Elastic Cartilage

59

Bone

A hard connective tissue that consists of living cells and mineralized matrix with-

Organic- protein fibers,

primarily collagen and other organic materials

Inorganic- hydroxyapatite (specialized crystals)

contain calcium and phosphate

The strength and rigidity of bone allow it to support and protect other structures within the body

Osteocytes (bone cells) located within lacunae of the matrix (similar to cartilage)

60

Two types of Bone

Cancellous or spongy

Has spaces between trabeculae beams or plates of bone and therefore

resemble a sponge

Located in the interior of the bones of the skull, vert, sternum, and pelvis, as

well on ends of long bones.

Compact bone

More solid with almost no space between many thin layers of lamellae of

bone.

Located on outer bones and shafts of long bones

61

Bone62

Muscle Shortens with force

3 main types

Skeletal

Cardiac

Smooth

Grouped according to structure and function.

Structure

Can be either striated, or non striated.

Function

Can be voluntary or involuntary

63

Skeletal muscle

attach to bone and assist with movement of the body

Cardiac muscle

Located in the heart and pumps blood under involuntary control

Smooth muscle

Located within the hollow organs such as the stomach ad intestines and

regulates the size of the organs, forces fluids through tubes , controls the

amount of light entering the eye.

64

Thus, the three muscle types are

Striated voluntary or skeletal muscle

Striated involuntary or cardiac muscle

Nonstriated involuntary or smooth

muscle

65

Muscle Tissue

Characteristics

Contracts or shortens with force

Moves entire body and pumps blood

Types

Skeletal

Striated and voluntary

Cardiac

Striated and involuntary

Smooth

Nonstriated and involuntary

66

Skeletal Muscle67

Cardiac Muscle68

Smooth Muscle69

Nervous

Found in the brain spinal cord and nerves

Able to conduct electric impulses called action potentials

Consists of neurons responsible for conductive ability and support

cells called neuroglia.

70

Neurons or nerve cells Actual conducting cells of nervous tissue

Composed of three parts

Cell body, contains nucleus,

Dendrites receive action potential and send them to the cell body

Shorter than axons, taper to a fine tip

Axon usually conduct action potential away from the cell body

Much longer than dendrites, constant diameter

71

Multipolar Neurons.

Neurons with several dendrites and one axon

Bipolar Neurons

Neurons that have a single dendrite and an axon

Unipolar Neurons.

Neurons with one axon and no dendrites

72

Neurons73

Neuroglia74

Functions of Blood

Distribution - nutrients, wastes, hormones, gases, etc.

Self-sealing – hemostasis

Disease/ infection fighting

Blood = connective tissue

extracellular

matrix:

Plasma

specialized cells:

(= Formed elements)

RBCs

WBCs

Plateletscolor ?

volume ?

Plasma Composition

Water 92%

Plasma proteins 7%

Other solutes 1%

Transports organic and

inorganic molecules,

formed elements, and heat

Plasma Proteins

Albumin (60%) Major contributor to osmotic concentration of

plasma. Transport of lipids and steroid hormones

Globulins (35%) Transport ions, hormones, lipids; immune

function

Fibrinogen (4%) Essential component of clotting system

(conversion to insoluble fibrin)

Regulatory proteins (< 1%) ????

Other Solutes

Electrolytes: Normal extracellular

fluid ion composition (????)

Organic nutrients: glucose, FA,

AA

Organic wastes: urea, bilirubin

Difference between Plasma and Interstitial Fluid :

Plasma has more:

Dissolved O2 O2 diffuses out into tissue

Dissolved proteins (too big to cross caps.)

Albumins

Globulins

globulins

and globulins

Fibrinogen

Similar concentration: Salts & small molecules

serum = plasma -

Difference between

plasma and serum?

. . . . 2 more things:

Most plasma proteins are made in liver. Exception: ?

Lipoproteins = particles containing lipids (cholesterol &

triglycerids) and proteins (albumins & globulins)

Formed Elements

Red and White Blood

Cells

Platelets

Platelets

WBCs

RBCs.1%

99.9%

Formed Elements cont.Why white blood cells???

RBCs = Erythrocytes

Measured by hematocrit or PCV

Most abundant blood cell: 1000 RBCs/1 WBC

Contain hemoglobin, carry O2

Very regular shape - biconcave discs

Anucleate: Lifespan ~ 120 days replacement rate ~

3 mio RBCs / sec

Structure of Hemoglobin (Hb)

Fe ion in heme

group

reversibly binds

O2

How many oxygen

molecules can 1

Hb molecule

carry?

ABO & Rh Blood Types

Blood groups (types) based on specific RBC surface

antigens (= proteins)

> 30 common varieties of antigens known. Most important

ABO & Rh blood type ?

ABO Blood typing:

4 combinations possible

A surface antigen = blood type A

B surface antigen = blood type B

both surface antigens = type AB

neither surface antigen = type O

Rh surface antigen = + blood type

no Rh antigen = negative blood type

. . . 2 - 8 months after birth:

Anti-A and anti-B antibodies can be formed in plasma !

normally NO

anti Rh present

Transfusion ReactionTransfusion of incompatible blood can be fatal!

Universal Donor vs.

Universal RecipientOnly for emergencies - must be

given slowly !

Clinical Brief

Anemia: p. 536

Reduced oxygen carrying ability of blood. Causes??

Polycythemia: Erythrocytosis: excessive increase in RBCs

Polycythemia vera:

Blood Doping: p. 545Via direct transfusion, or

EPO use

WBCs = Leukocytes

Quantity and type determined by differential WBC count

Circulating WBCs are only a small fraction of total WBCs. Most are located in ?

Diapedesis

Chemotaxis

Granulocytes and

Agranulocytes

http://www.whfreeman.com/immunology/CH01/figure01-05.gif

http://www.whfreeman.com/immunology/CH01/figure01-05.gif

Neutrophil (= PMN)

Up to ~ 70% (~ 2/3) of circulating WBCs

Cytoplasm packed with pale granules containing lysosomal

enzymes

phagocytic

Eosinophil

~ 2% - 4% of circulating WBCs

Granules stain with eosin

Increased in allergies and parasitic infections

Basophil

< 1% of circulating WBCs

Granules stain with basic dyes and contain histamine

Discharge of histamine promotes inflammation at site

of injury (Similar to mast cells)

Monocyte


Large kidney shaped nucleus

In tissue called Macrophage

Lymphocytes


Relatively small (slightly larger than RBCs)

Large round nucleus

B, T, NK

Platelets = Thrombocytes

Cell fragments of Megakaryocytes

(~ 4,000 thrombocytes per Megakaryocyte)

~ 160 m

Lifespan ~ 12 days

involved in blood clotting

Abnormal Blood Cell Counts

Leukopenia < 2,500/ L (normal 6000 – 9000)

Leukocytosis > 30,000/ L

Thrombocytopenia: < 80,000/ L (normal ~ 350,000)

Thrombocytosis: > 1,000,000/ L

Also

Lymphopenia vs. _____________

_________vs. Neutrophilia

Hemopoiesis = Blood Cell Formation

Hemocytoblasts: One type of stem cell for all blood cells

In red bone marrow

. . . then differentiation

into 4 types of

progenitor stem cells:

Erythroblast

Myeloblast

Monoblast

Lymphoblast

Fig 20.8

tissues of the body - bowen university

Documents