Module #2 Histology
Histology – the study of tissues
Four tissue types:Epithelial ConnectiveMuscleNerve
Epithelial
Tissuehttp://lima.osu.edu/biology/images/anatomy/Stratified%20squamous%20epithelium%20400X.jpg
General Features of Epithelial Tissue
•Cells are closely packed with little extracellular material (between cells)
•Are in continuous sheets
•Single or multiple layered
General Features of Epithelial Tissue
•Epithelia is avascular meaning “without blood vessels”.
•Nutrients and wastes are exchanged by diffusion with the adjacent connective tissue.
General Features of Epithelial Tissue
•have a free surface which is exposed to a body cavity, lining of an internal organ, or the exterior of the body, and
• a basal surface which is attached to the basement membrane.
basal surface
General Features of Epithelial Tissue
•Subject to wear, tear and injury, so has a high capacity for renewal (high mitotic rate).
•Functions include protection, filtration, lubrication, secretion, digestion, absorption, transportation, excretion, sensory reception, and reproduction.
General Features of Epithelial Tissue
•Epithelial tissue sits on a basement membrane located between it and the tissue underneath.
http://www.ouhsc.edu/histology/Glass%20slides/13_04.jpg
Epithelial tissue
Connective tissue
There are two kinds epithelial tissue based on function:
(1) lining or covering epithelium – covers the skin and outside of some internal organs, forms the inner lining of body cavities, blood vessels, and internal organs.
Epithelial Tissue con’t
There are two kinds epithelial tissue (function):
(2) glandular epithelium - consists of cells that secrete substances. (ex. Thyroid/sweat/oil glands)
Epithelial Tissue con’t
Epithelial tissue can be divided into categories based on……
>the shape of the cells and
> the number of layers of cells.
SHAPES of epithelium:
1. Squamous -flat cells-thin which allows substances to pass through (diffuse) them. -have limited cell structures due to size
2. Cuboidal cube shapedImportant in secretion and absorptionHave more cell structures than squamousUses active transport to secrete and absorb substances
3. Columnar cells are tall and cylindrical Have the most cell structures Most complex Most secretion ability
4. Transitional •cells can readily change shape from squamous to columnar•change shape due to stretching, of body parts. (ex. Found in bladder)
Arrangement of Layers
1. Simple epithelium a single layer of cellsfound in areas where diffusion, osmosis, filtration, secretion and absorption occur.Can be squamous, columnar, or cuboidal Ex. lungs
Arrangement of Layers
2. Stratified epithelium contains two or more layers of cells protects underlying tissues found where there is wear and tearEx. Skin Named by the free surface.
Arrangement of Layers
3. Pseudostratified epithelium contains a single layer of a mixture of cell typeshas a stratified appearance but is a single layerAll cells touch basementmembrane
Glandular EpitheliumColumnar epithelium that contains special cells capable of synthesizing and secreting certain substances such as enzymes, hormones, milk, mucus, sweat, wax and saliva
Glandular Epithelium
Goblet cells :
Special columnar cells that their function is to secret mucin which mixes with water to form mucous - intestines
Goblet cell
Glandular Epithelium
There are two types of glands:
1. Exocrine glands • secrete their products to
the target by ducts• most glands in the body
are exocrine glands (sweat/salivary)
• All have secretory portion and a duct
Exocrine Gland
Exocrine glands come in many arrangements/types:
Glandular EpitheliumThere are two types of glands:
1. Exocrine glands
Types of exocrine glands based on how they secrete:
a. Merocrine glands – by exocytosis (without losing cellular material) into the duct.
Example sweat glands.
Merocrine gland directly secretes into duct.
http://www.med.umich.edu/histology/fieldTrip/sweatGland.jpg
Glandular EpitheliumThere are two types of glands:
1. Exocrine glands
Types of exocrine glands based on how they secrete: a. Merocrine glands
b. Apocrine glands - a portion of the plasma membrane containing the secretion and some cytoplasm buds off the cell and enters the duct.
Ex. Mammary glands
Apocrine Gland
There are two types of glands:
1. Exocrine glands
Types of exocrine glands based on how they secrete: a. Merocrine glands
b. Apocrine glands
c.holocrine gland - the entire cell containing its secretion
disintegrates in the duct.
Ex. Oil glands
Glandular EpitheliumThere are two types of glands:
1. Exocrine glands
2. Endocrine gland no ducts secrete hormones by exocytosis intointerstitial fluids that surround cellsand blood stream picks them up.Ex. Thyroid gland
Endocrine Glands
Type Function LocationSimple Squamous Diffusion Blood vessels, lungsSimple Cuboidal Diffusion and secretion Kidneys
Simple Columnar Mucous producing Stomach and intestines
Stratified Squamous Protection, secreting Skin, lining mouth
Stratified Cuboidal Protection, secreting Protect Salivary glands - rare
Stratified Columnar Protection, secreting Pharynx, larynx, uterus - rare
Stratified Transitional Stretches, changes shape Urinary bladder
Epithelial Tissue – Functions and locationsHandout
Why does skin flake off? Cells at top of skin are so far from nutrients that they are dead.
Keratin – protein that fills dead epidermal cells at top layer
Keratinized membrane – top layer of skin cells that are dead and filled with keratin.
Where quiz stops
CONNECTIVE TISSUE
FUNCTION: insulate, support and bind (infrastructure)
CONNECTIVE TISSUE continued
CHARACTERISTICS:
Greater space between cells (extracellular space) compared to epithelial tissue
cells secrete extracellular material or MATRIX which fills space between cells
CONNECTIVE TISSUE continued
CHARACTERISTICS:
Matrix is the material between the cell which contains ground substance (non-collagenous part of matrix) and collagen protein fibers.
CONNECTIVE TISSUE continued
CHARACTERISTICS:
Connective Tissue is classified according to the type of extracellular matrix it produces
CONNECTIVE TISSUE
TYPES:1. connective tissue proper2. cartilage3. bone4. blood
TYPE 1: Connective Tissue Proper
Guess how many kinds of connective tissue proper
there are?
4
TYPE 1: Connective Tissue Proper
Four types of Connective Tissue Proper:
A. Loose connective tissueExtracellular matrix is not strong
Is used for light binding and flexibility
Also called areolar connective tissue
TYPE 1: Connective Tissue Proper
Four types of Connective Tissue Proper:
A. Loose connective tissue
Found between the skin and the muscles holding the skin to musclesHas fibroblasts which make tissue’s ground substance, protein fibers, collagen fibersMature fibroblast are called
fibrocytes
Loose Connective Tissue Proper
fibroblast
Four types of Connective Tissue Proper:A. Loose connective tissue
B.Dense irregular connective tissue
Part of the skin
Collagen fibers more densely packed than loose connective tissue
B. dense irregular connective tissue continued
Denser packing give tissue more strength
Irregular because fibers run every which way
Dense irregular connective tissue proper
Four types of Connective Tissue Proper:A. Loose connective tissueB. Dense irregular connective tissue
C. Dense regular connective tissue properCollagen fibers run in one
direction giving more strength called tensile strength
Found in tendons which hold muscle to bones and ligaments that hold bone to bone
c. Dense regular connective tissue proper
Tendons and ligaments take a long time to heal when injured because of dense amount of extracellular material (fibers, etc.) that they must manufacture.
Dense regular connective tissue proper
Four types of Connective Tissue Proper:A. Loose connective tissueB. Dense irregular connective tissueC. Dense regular connective tissue proper
D. Adipose tissue
Fatty tissue
it has fat cells in it as well as connective tissue cells
D. Adipose tissue
Function is to store energy, insulate, and to hold organs in place
Example – kidneys are protected and held in place by adipose tissue
CONNECTIVE TISSUE
TYPES:1. connective tissue proper
2. Cartilage Supporting connective
tissue with tensile strength and supporting fibers of collagen in the ground substance
CONNECTIVE TISSUE
TYPES:1. connective tissue proper2. Cartilage
• Firmer than connective tissue proper
• Has no blood supply• Thin matrix• Found in nose, ear,
larynx• Often replaced by bone
CONNECTIVE TISSUE
TYPES:1. connective tissue proper2. Cartilage
Chondroblasts – immature cartilage cells that produce the matrix fibers.
CONNECTIVE TISSUE
TYPES:1. connective tissue proper2. Cartilage
Chondrocytes – mature chondroblast that become trapped in matrix and live in hollow spaces called lacuna in the cartilage tissue.
Lacuna (histology), a small space containing an osteocyte in bone or chondrocyte in cartilage
CONNECTIVE TISSUE
TYPES:1. connective tissue proper2. Cartilage
3 types of cartilage:
A. Hyaline cartilage occurs at end of bones,
external ear, fetal skeleton, nose, ribs and vertebrae
Weakest and most common
CONNECTIVE TISSUE
TYPES:1. connective tissue proper2. Cartilage3 types of cartilage:
B. Elastic cartilage found in epiglottis and
external ear contains elastic fibers great flexibility and is able to
withstand repeated bending
CONNECTIVE TISSUE
TYPES:1. connective tissue proper2. Cartilage3 types of cartilage:
C. Fibrous cartilage Strongest Dense collagen fibers with limited
ground substance Found in disk between vertebrae and
skull Where bears great amount of weight Has fibrous appearance
CONNECTIVE TISSUE - Cartilage
CONNECTIVE TISSUE
TYPES:1. connective tissue proper2. Cartilage
3. Bone: Hardest connective tissue
Consist of cells, collagen fibers, and mineralized (calcium and phosphate) ground substance
CONNECTIVE TISSUE
TYPES:1. connective tissue proper2. Cartilage3. Bone:
Ground substance becomes hard or calcified through a process known as calcification
CONNECTIVE TISSUE
TYPES:1. connective tissue proper2. Cartilage3. Bone:
Has a rich blood supply
Properly known as osseous tissue
CONNECTIVE TISSUE
TYPES:1. connective tissue proper2. Cartilage3. Bone
Types of bone cells:
A. Osteoblasts- make components of bone
CONNECTIVE TISSUE
TYPES:1. connective tissue proper2. Cartilage3. Bone
Types of bone cells:
B. Osteocytes – mature osteoblasts found in lacuna
CONNECTIVE TISSUE
TYPES:1. connective tissue proper2. Cartilage3. Bone
Types of bone cells:
C. Osteoclasts – reasorb bone and remodel it
CONNECTIVE TISSUE
TYPES:1. connective tissue proper2. Cartilage3. Bone
4. Blood transports
Also known as vascular tissue
Two types of cells – red and white
CONNECTIVE TISSUE
TYPES:1. connective tissue proper2. Cartilage3. Bone4. Blood
Ground substance = proteins in blood
Has fluid part – blood plasma
Has clotting fibers
QUIZ
New Topic: Membranes
Membrane = layers oftissue
There are three categories of membranes:
New Topic: Membranes
There are three categories of membranes:
1. Mucous found in linings of organ systems that open to the outside
New Topic: Membranes
There are three categories of membranes:
1. Mucous
Ex. Respiratory system, reproductive system, digestive system
Traps foreign material
New Topic: Membranes
There are three categories of membranes:
2. Serous line the body cavities that do not open directly to the outside
they cover the organs located in those cavities
New Topic: Membranes
There are three categories of membranes:
2. Serous
are covered by a thin layer of serous fluid that lubricates and is secreted by the epithelium
New Topic: Membranes
There are three categories of membranes:
2. Serous
Serous fluid lubricates the membrane and reduces friction and abrasion when organs move against each other or the cavity wall.
New Topic: Membranes
There are three categories of membranes:
3. Synovial membranes
connective tissue membranes that line the cavities of the freely movable joints such as the shoulder, elbow, and knee.
New Topic: Membranes
There are three categories of membranes:
3. Synovial membranes
secrete synovial fluid into the joint cavity, and this lubricates cartilage on the ends of the bones so that they can move freely and without friction.
New Topic: tissue repair
Remember: Tissues are made up of cells.
Two types of cells that make up tissue based on function:
1. Stromal cells – provide structure and support to tissue; usually connective tissue
New Topic: tissue repair
Remember: Tissues are made up of cells.
Two types of cells that make up tissue based on function:
1. Stromal cells – provide structure and support to tissue
2.Parenchymal cells – cells that actually perform the function of the tissue
Organ Parenchyma
kidney nephron
lungs alveoli, respiratory bronchiole, alveolar duct and terminal bronchiole
spleen white pulp and red pulp
brain neuron
liver hepatocyte
New Topic: tissue repair
Categories of cells based on ability to reproduce or regenerate:1. Labile cells cells that multiply constantly
throughout life Most of cells in body ex. Parenchymal epithelial
cells replace themselves quickly
New Topic: tissue repair
Categories of cells based on ability to reproduce or regenerate:
2. Stable cells only multiply when receive
external stimulus to do so ex. Bone parenchymal cells
when a bone is broken can reproduce and repair the broken bone
New Topic: tissue repair
Categories of cells based on ability to reproduce or regenerate:
3. Permanent cells do not have the ability to
multiply
Nervous system parenchymal cells (neurons) are permanent; can’t be replaced.
New Topic: tissue repair
So, if cells are parenchymal permanent and die they will be replaced by labile stromal cells..
This is why brain damage or heart damage is said to be irreversible.
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