Transcript tissues - Immaculateheartacademy.org

Tissues, Glands and Membranes
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A tissue is a group of cells that have a
similar structure and function
The microscopic study of tissues is called
histology
Four Types of Tissue
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Epithelial
Connective
Muscle
Nervous
Epithelial Tissue
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Epitihelial – “ Covering Lining”
Covers internal and external surfaces
throughout the body
Three parts: free surface
basement membrane
very little extracellular space
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Functions of the epithelial cell
Protects the underlying structures- for example
the skin
Acts as a barrier to certain substance- for
example water, toxic molecules, and
microorganisms
Also allows the passage of certain substances –
for example oxygen and carbon dioxide
Secretes substance – for example secretions
from sweat glands
Absorbs substances – for example vitamins,
minerals
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Classified according to the number of layers and
the cell shape
#of layers
Simple (one layer)
Pseudo stratified
Stratified
Transitional
Cell shape
Squamous
Cuboidal
Columnar
Columnar
Squamous
Keratinized
Non Keratinized
Roughly cuboidal to columnar
when not stretched,squamous
when stretched
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The structure relates to the function
Simple epithelium- found in movement
epithelium
- gasses across wall of alveoli
- filtration of fluid across kidneys
- secretion of glands
- nutrient absorption
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Sratified epithelium
well adapted for its protective function
as outer layers are damaged , they are
replaced by deeper cell layers
Found where abrasions may occur, such as
skin, anal canal and vaginal canal
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Differences also reflected in the cell shape
Flat and thin cells – for diffusion in lungs and
filtration in kidneys
Cuboidal or columnar cells are cells with major
functions of secretion or absorption. They are
larger because they contain more organelles for
all the functions they must perform e.g.
columnar cells of the stomach lining have
secretory vesicles that secrete mucus.
Free Surface of the cell
Cell Connections
Cell Connections
Tight Junctions
Desmosoes
Hemidesmosomes
Gap junctions
Glands
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Glands- A gland is a multicellular
structure that secretes substances on to a
surface, into a cavity or into the blood
Most are made of epithelial cells
Types of Glands
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Exocrine- glands that have ducts
- simple- no branches
-compound- branches
ends- 1-tubular
straight tubular
coiled tubular
2- acinar/ alvoelar or saclike
3- both tubuloacinar
Types of Exocrine Glands
Endocrine Glands
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Endocrine-have no ducts and empty their
secretions directly into the blood
Secretions are called hormones and these
hormones are carried to other parts of the
body by the blood
Connective Tissue
Connective Tissue
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Connective Tissue structure – large
amounts of extracellular materials that
separate cells from one another
This extracellular matrix is divided into three
parts:
-protein fibers
- ground substance consisting of non
fibrous protein and other molecules
- fluid
Connective Tissue Matrix
Protein Fibers
- Collagen Fibers- resemble microscopic ropes,
flexible but resist bending
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- Reticular Fibers- very fine short collagen fibers that
branch to form the supporting network
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- Elastic Fibers- structure similar to coiled metal bed
springs
but after being stretched , elastic fibers recoil to their
original shape
Connective Tissue Matrix
Ground Substance
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Ground Substance is the shapeless
background against which cells and
collagen fibers are seen in the light
microscope
Made up of highly structured molecules
Consists of Proteoglycans (proteins and
carbohydrates that trap water)
Connective Tissue Matrix
Cells of the matrix
How Do We Name Connective Tissue ?
According to Their Functions
examples:
Blast- produces the matrix
Cyte – maintains the matrix
Clast-break down the matrix for
remodeling
Macrophage
Mast Cell
Functions of the Connective Tissue
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Encloses and Separates
Connecting tissue to one another
Supporting and Moving
Storing
Cushioning and insulating
Transporting
Protecting
Classification of Connective Tissue
Loose (areolar)
 Adipose
 Dense Connective Tissue
- Dense collagenous connective
A) Collagen arranged in same direction
B) Collagen arranged in many directions
Dense elastic connective tissue
A)Elastic arranged in many directions
b) Elastic fibers arranged in same direction
Cartilage
Hyaline
FIbrocartilage
Elastic Cartilage
Bone
Blood
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Loose Areolar Tissue
-mostly collagen, few elastic and
widely separated from each other
Produced by the fibroblast
This is the tissue that fills in the
spaces
Loose Connective TISSUE
Adipose Tissue
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Has very little collagen and elastic fibers
Large cells filled with lipids
Pads of protection and thermal insulation
Dense Connective Tissue
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Densely packed fibers that produced by the
fibroblast
Dense Collagenous- mostly collagen
tendons, ligaments, capsules around
organs
same direction in tendons, different in
organs
Dense Elastic Tissue- abundant elastic fibers
among collagen fibers
vocal cords, walls of large arteries
Dense Elastic
Cartilage
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Composed of cartilage cells or
Chondrocytes
Located in the matrix along with collagen
Amongst the extracellular matrix
It gives the matrix resilience
Hyaline
Fibro
Elastic
Hyaline Cartilage
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The most abundant type of cartilage
Ends of bones where they come together
to form joints. It is the smooth and
resilient
Surfaces that withstand repeated
compression
Costal , respiratory, and nasal cartilges
Fibrocartilage
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Has more fibrous tissue than does hyaline
cartilage
, bundles of collagen
Resists pulling or tearing
Found in the disks between vertebrae and
in some joints
Elastic Cartilage
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Has elastic fibers, collagen proteoglycans
Coiled fibers amongst bundles of collagen
fibers
Can recoil to its original shape when bent
External ear, epiglottis, auditory tube
Bone
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Is hard connective tissue that consists of
cells and a mineralized matrix
Osteoblasts secrete the matrix called
lamellae
osteocytes are located in lacune
The Osteon ( Haversion system) consist
of central canal with blood vessels,
osteocytes and lamellae
Haversion System/Osteon
Blood
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Here the matrix is a liquid which enables
the blood to move through the vessels to
carry nutrients and other materials
Muscle Tissue
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Main Characteristic is its ability to
contract , making movement possible
Contractile proteins in the muscle cells
themselves, called actin and myosin
Muscle cells are called muscle fibers
because they resemble tiny threads
Three Types of Muscle Tissue
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Skeletal Muscle
Cardiac Muscle
Smooth Muscle
Skeletal Muscle
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Normally thought of as “muscle”
Meat of animals, 40% of persons body weight
Attaches to the skeletal system and enables body
movement
Long and cylindrical cells with several nuclei per cell Some
cells are the entire length of the muscle
Striated,
Vountary
Smooth Muscle
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Forms the hollow walls of the organs and
is also in the skin and eyes
Movement of food and emptying of the
Urinary Bladder
Involuntary
Tapered at each end , have a single
nucleus and are not striated
Cardiac Muscle
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Muscle of the heart and is responsible for
Involuntary control
Cylinder in shape and shorter than skeletal
Striated and one nucleus
Connected by intercalated disks
Classification of Muscles
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Skeletal
Voluntary
Striated
>1nuclei
Smooth
involuntary
not striated
1 nuclei
Cardiac
involuntary
striated
1 nuclei
Nervous Tissues
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Forms the brain, spinal cord and nerves
Coordinates and controls many body activities
Conscious and unconscious
Awareness, emotion, reasoning
Communicate through action potentials
Cell= neuron or nerve cell responsible for
conduction of action potentials
Neuron – cell body , dendrites and axons
Neuroglia surrounding support cells
Neurons and Glial cells
Membranes
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Serous Membranes
simple squamous epithelium resting on
delicate layers of loose connective tissue
cavities and cover the organs inside
these cavities
secretes serous fluid which lines the
cavitites
prevents trauma and damage
Membranes
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Pleural- lungs Pleuritis
Pericardium- heart - Pericarditis
Peritoneal other
- Peritonitis
Other Membranes
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Cutaneous
Synovial
Periosteal