Ingegneria delle tecnologie per la salute

Fondamenti di anatomia e istologia

aa. 2017-18

Anatomia umana Edizione italiana a cura di Fabrizio Michetti MCKINLEY - O'LOUGHLIN Data di pubblicazione: maggio 2014 Prezzo: 49,50 € ISBN: 978-88-299-2655-8 Codice Piccin: 1312165 Libro in italiano

Atlante di anatomia Edizione italiana a cura di Elena Donetti KAMINA Data di pubblicazione: settembre 2014 Prezzo: 45,00 € ISBN: 978-88-299-2668-8 Codice Piccin: 1100850 Libro in italiano

Colorare l'anatomia Edizione italiana a cura di Raffaele De Caro e Sergio Galli KAPIT - ELTON Data di pubblicazione: marzo 2016 Prezzo: 20,00 € ISBN: 978-88-299-2747-0 Codice Piccin: 1101200 Libro in italiano

Lezione 3. Cenni di embriologia ed istologia generale.

https://human.biodigital.com/index.html

https://www.openstaxcollege.org/files/textbook_version/hi_res_pdf/13/col11496-1.7_20150715-OP.pdf

https://lectureug5.files.wordpress.com/2014/02/difiores-atlas-of-histology-with-functional-correlations-11th-ed.pdf

THE TISSUE LEVEL OF ORGANIZATION

After studying this chapter, you will be able to: • Identify the main tissue types and discuss their roles in the human body • Identify the four types of tissue membranes and the characteristics of each that make them functional • Explain the functions of various epithelial tissues and how their forms enable their functions • Explain the functions of various connective tissues and how their forms enable their functions • Describe the characteristics of muscle tissue and how these enable function • Discuss the characteristics of nervous tissue and how these enable information processing and control of muscular and glandular activities

our body: at least 200 distinct cell

types.

same internal structures but vary

enormously in shape and function.

occur in organized layers: tissue

starts as a single cell at fertilization

and it gives rise to trillions of cells,

each built from the same blueprint, but

organizing into tissues and becoming

irreversibly committed to a

developmental pathway.

Tissue = a group of cells found

together in the body, that share a

common and morphological features

and are arranged in an orderly pattern

that achieves the tissue’s functions.

many types of cells, but organized

into 4 broad categories of tissues:

1. epithelial

2. connective

3. muscle

4. nervous

with a specific functions that

contribute to the overall health and

maintenance of the body.

Histology = microscopic study of

tissue appearance, organization, and function.

Types of Tissues

Histology is a visual, as well as a very

colorful, science that is studied with the

aid of a light microscope. The prepared

specimens for examination are thinly

sliced, placed on a glass slide, stained

with a variety of stains, and examined

with a light microscope via a light beam

that passes through the tissues that are

fixed on the slide.

Tissue Preparation—Light Microscopy

Antonie van Leeuwenhoek (1632–1724) is credited with bringing the microscope to the attention of biologists

FIXATION

= prompt immersion of the specimen with

different chemical solutions, to preserve a

section of tissue or organ for histologic

examination

essential in order to permanently

preserve structural and molecular

composition of specimen.

to further accelerate penetration and

proper fixation process, tissue

specimen is first cut into small pieces

and then immersed into fixative.

hardens specimen for sectioning,

causes cross-linkage of

macromolecules within the cells,

reduces cellular degeneration,

preserves integrity of cells and tissues,

and increases their affinity to take up

different stains.

most commonly used fixative for light

microcopy is neutral-buffered

FORMALDEHYDE.

Tissue Preparation—Light Microscopy

Aldehyde fixatives form crosslinks between proteins.

Tissue Preparation—Light Microscopy

POSTFIXATION

After fixation, water must first be removed by

passing it through a series of ascending ALCOHOL

(ethanol) concentrations, usually from 70 to 100%

then specimen must be cleared of alcohol by

passing it through several changes of such clearing

agents as XYLENE

Once the specimen is impregnated with the clearing

agent xylene, it is then placed in a warm mold

containing melted PARAFFIN. Once removed from

the heat source, the paraffin in the mold cools,

solidifies, and encases the specimen.

paraffin block then trimmed to the size of the

specimen and mounted in an instrument called a

MICROTOME [precisely advances the paraffin block

so that the sections are cut at specific and

predetermined increments with a steel knife] =

sections are normally cut at 3-10 μm thickness.

thin paraffin sections are then collected and floated

in a warm water bath and placed onto a glass slide

that has been covered with a thin layer of albumen,

which serves as an adhesive medium for the

specimen.

Tissue Preparation—Light Microscopy

Staining of Sections

paraffin sections on the glass slide

are colorless needs to be

stained.

paraffin must first be dissolved

from the specimen with solvents,

such as xylene, and the sections

rehydrated with a series of

decreasing alcohol concentrations.

hydrated sections can then be

stained with a variety of water-

soluble stains, which selectively

stain various components of the

specimen

Most of the stains used for

histologic slide preparations act

like acidic or basic compounds:

structures that stain most readily

with basic stains are called

BASOPHILIC, and those that stain

with acidic stains are called

ACIDOPHILIC [most common

stains are hematoxylin and eosin

stains]

Staining of Sections

Staining of Sections

Staining of Sections

Staining of Sections

Staining of Sections

Staining of Sections

Staining of Sections

Staining of Sections

Staining of Sections

Transmission and Scanning Electron Microscopy

Interpretation of Histologic Sections

the most challenging and difficult aspects of histology:

interpretation of what the two-dimensional histology

sections represent in three dimensions.

Histologic sections = thin, flat slices of fixed and stained

tissues or organs mounted on flat glass slides.

sections normally composed of cellular, fibrous, and

tubular structures cut in different planes variety of

shapes, sizes, and layers may be visible, depending on

the plane of section.

Fibrous structures are solid and are found in connective,

nervous, and muscle tissues.

Tubular structures are hollow and represent various types

of blood vessels, lymph vessels, glandular ducts, and glands of the body.

Planes of Section of a Round, Solid Object

Planes of Section Through a Hollow Structure or a Tube

Planes of Section Through a Hollow Structure or a Tube

Cell microscopic anatomy (TEM)

Ciliated and nonciliated cells

Junctional complex

Basal region

Basal region in ions transporting cell

Cilia and microvilli

Nuclear envelope and pores

Mitochondria

RER

SER

Golgi apparatus

Lysosomes

Mitosis

The 4 Types of Tissues

1. Epithelial tissue (epithelium) = sheets

of cells that cover exterior surfaces of

the body, internal cavities and

passageways, and forms certain

glands.

2. Connective tissue = binds cells and

organs together (functions: protection,

support, and integration of all parts of

the body)

3. Muscle tissue = excitable, responding

to stimulation and contracting to provide

movement, and occurs as 3 major

types: skeletal (voluntary) muscle,

smooth muscle, and cardiac muscle in

the heart.

4. Nervous tissue = also excitable,

allowing the propagation of

electrochemical signals in the form of

nerve impulses .

The 4 Types of Tissues

Organs are made of many different tissues of the 4 fundamental types

sections through 4 different organs: Intestines, Skin, Lung, & Trachea. (each organ is made of multiple tissues and that their are variations on how the tissues are designed)

Embryonic Origin of Tissues

totipotent

three major cell lineages established within the embryo

Embryonic Origin of Tissues

3 lineages of embryonic cells forms 3

distinct germ layers identified by its

relative position:

1. ectoderm (ecto-= “outer”),

2. mesoderm (meso- = “middle”),

3. endoderm (endo- = “inner”).

Embryonic Origin of Tissues

!!! epithelial tissue

originates in all

three layers,

whereas nervous

tissue derives

primarily from the

ectoderm and

muscle tissue from mesoderm.

Tissue membrane = thin layer or sheet of

cells that covers the outside of the body (for

example, skin), the organs (for example,

pericardium), internal passageways that lead

to the exterior of the body (for example,

abdominal mesenteries), and the lining of the moveable joint cavities.

Tissue Membranes

2 basic types

1. connective tissue 2. epithelial membranes

Tissue Membranes

1. Connective Tissue Membranes = formed solely from connective

tissue, encapsulate organs, and line our movable joints (synovial

membrane)

2. Epithelial Membranes = composed of epithelium attached to a

layer of connective tissue

i. mucous membrane (mucosae) = line the body cavities and hollow

passageways that open to the external environment, and include the

digestive, respiratory, excretory, and reproductive tracts. Mucous,

produced by the epithelial exocrine glands, covers the epithelial layer.

The underlying connective tissue, called the lamina propria, supports

the epithelial layer.

ii. serous membrane = composed of mesodermally derived epithelium

called the mesothelium that is supported by connective tissue, line

coelomic cavities (do not open to outside).

iii. cutaneous membrane (skin) = stratified squamous epithelial membrane resting on top of connective tissue.

The 4 Types of Tissues

The 4 Types of Tissues: epithelial

Epithelial Tissue

share structural/ functional features: highly cellular, with little or no extracellular

matrix between cells cell junction = specialized intercellular

connection between cell polarity = differences in structure and function

between the exposed or apical facing surface of the cell and the basal surface

basal lamina = (a mixture of glycoproteins and collagen) provides an attachment site for the epithelium, separating it from underlying connective tissue and attaches to a reticular lamina, which is secreted by the underlying connective tissue, forming a basement membrane that hold it all together.

nearly completely avascular. capable of rapidly replacing damaged and dead

cells.

= essentially large sheets of cells covering all the surfaces of the body exposed to the outside world + lining the outside of organs + much of the glandular tissue of the body;

Epithelial Tissue

basement membrane

Epithelial Tissue

basement membrane

Epithelial Tissue

Generalized Functions of Epithelial Tissue • provide the body’s first line of protection from physical, chemical, and biological wear and

tear, controlling permeability and allowing selective transfer of materials across a physical barrier

• are sometimes capable of secretion and release mucous and specific chemical compounds onto their apical surfaces.

The Epithelial Cell typically characterized by the polarized distribution of organelles and membrane-bound proteins between their basal and apical surfaces: certain organelles are segregated to the basal sides, whereas other organelles and extensions, such as cilia (microscopic extensions of the apical cell membrane that are supported by microtubules), when present, are on the apical surface and beat in unison and move fluids as well as trapped particles.

Epithelial Tissue

Cell to Cell Junctions Cells of epithelia are closely

connected and are not

separated by extracellular

material. 3 basic types of

connections allow varying

degrees of interaction between

the cells:

1. tight junctions,

2. anchoring junctions, 3. gap junctions

Epithelial Tissue

Classification of Epithelial Tissues

classified according to the shape

of the cells and number of the cell

layers formed. Transitional

describes a form of specialized

stratified epithelium in which the shape of the cells can vary.

Epithelial Tissue

Classification of Epithelial Tissues

classified according to the shape of the cells and number of the cell layers

formed. Transitional describes a form of specialized stratified epithelium in which the shape of the cells can vary.

Epithelial Tissue

Both simple and pseudostratified columnar epithelia

are heterogeneous epithelia because they include

additional types of cells interspersed among the

epithelial cells. For example, a goblet cell is a mucous-secreting

unicellular “gland” interspersed between the columnar epithelial cells of mucous membranes

goblet cell

Epithelial Tissue

different categories of epithelial cell tissue cells

Epithelial Tissue

different categories of epithelial cell tissue cells

Epithelial Tissue

Glandular Epithelium gland = a structure made up of one or more cells modified to synthesize and secrete chemical substances; most glands consist of groups of epithelial cells. 1. Endocrine Glands a ductless gland that releases secretions (hormones) directly into surrounding tissues and fluids (endo- = “inside”), that are part of regulatory system 2. Exocrine Glands gland whose secretions leave through a duct that opens directly, or indirectly, to the external environment (exo- = “outside”). through a tubular duct that leads to the epithelial surface

Epithelial Tissue

Exocrin Glandular Structure Exocrine glands classified: • unicellular = scattered

single cells (goblet cells)

• multicellular (classified by

structure)

Epithelial Tissue

Exocrin Glandular Methods and Types of Secretion Exocrine glands classified

• mode of secretion

• nature of the substances released

serous gland watery, blood-plasma-like secretions mucous gland watery to viscous products rich in the glycoprotein mucin. mixed glands both serous and mucous glands and release both types of secretions.

Epithelial Tissue

Sebaceous Glands secrete oils that lubricate and protect the skin and

are holocrine glands (are destroyed after releasing their contents, new glandular cells form to replace the cells that are lost).

Epithelial Tissue

Type of Tissue Function Location

Pseudostratified columnar removing dust and particles from airways, has cilia

lines the respiratory passageways

Epithelial Tissue

Simple Columnar Absorption lines the uterus and most organs of the digestive tract

Epithelial Tissue

Simple Cuboidal Secretion and Absorption glands, kidney tubules, ovaries

Epithelial Tissue

Simple Squamous Diffusion and Filtration lungs, walls of capillaries and vessels

Epithelial Tissue

Stratified Squamous Protects underlying cells skin(keratinized) and the throat, vagina, mouth (soft)

Epithelial Tissue

Stratified Cuboidal Protection lines ducts of the mammary glands, sweat glands, pancreas

Epithelial Tissue

Stratified Columnar Protection, secretion male urethra and vas deferens, parts of the pharynx

Epithelial Tissue

Transitional (unstretched) Specialized to become distended urinary tract