histology the tissue level of organization. histology the study of tissues and how tissues are...
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Histology
The Tissue Level of Organization
Histology The study of tissues and how tissues
are combined in various ways to form organs & membranes of the human body.
The human body contains four primary types of tissues: Epithelial Connective Muscle Neural (nerve) tissue.
I. Epithelial Tissue Made of cells with little space
between cells. The cells are so tightly packed
together that blood vessels can’t penetrate between them and is called avascular.
Epithelial Tissue In certain areas of the body epithelial tissue may perform
the following functions: Control Permeability: Provide Sensitivity Provide Physical Protection: Produce Secretions:
Epithelial Tissue Two Types Covering & Lining and
Glandular.1.Covering & Lining Epithelia is
classified based on the number of cell layers and the cell shape.
2.Glandular Epithelia is classified based on if the tissue secretes its product into a gland or not.
Covering & Lining Epithelial Classification based on:
Number of cell layers.• Simple- single layer.• Stratified- many layers.• Pseudostratified- appears to be many layers
but is actually a single layer. Cell Shape.
• Squamous- Flat.• Cuboidal- Cube shaped.• Columnar- Rectangular.• Transitional- Cuboidal & Squamous.
Simple Squamous Flat cells with central nucleus. Function: Permits the efficient
diffusion of materials. Location: Lining of body cavities,
lines the walls of blood & lymphatic vessels, forms the walls of air sacs.
Simple Squamous
Simple Cuboidal Single layer of cube-shaped cells
with central nucleus, often have cilia and/or microvili.
Function: Forms the walls of small ducts and tubes that carry secretions.
Location: Kidneys, Liver, Glands.
Simple Cuboidal
Simple Columnar Single layer of rectangle cells whose
nuclei lie near the base (basal) of the cell.
Function: Absorb and secrete; mucus, enzymes, etc.
Location: Uterus, Stomach, Digestive Tract, Bronchi.
Simple Columnar
Stratified Squamous Multiple layers, only top layer is
squamous the deeper layers are cubiodal and or columnar.
Function: Covers areas that must resist wear & tear, protects openings of the body from abrasions.
Location: Esophagus, Mouth, Nose, Vagina, etc.
Stratified Squamous
Stratified Cuboidal Function: Protection. Location: Sweat Glands. Mammary
Glands, Salivary Glands.
Stratified Cuboidal
Stratified Columnar Function: Protection & Secretion. Location: Male Urethra, some large
ducts, rare in the body.
Stratified Columnar
Pseudostratified Columnar Appears to be multilayered but is
not. Function: Often contains cilia which
creates currents to move mucus. Location: Lines parts of respiratory
tract, such as the trachea & bronchi.
Pseudostratified Columnar
Pseudostratified
Transitional Multilayered cube-like cell shape. Function: Can stretch(elasticity) and
return to the original shape (extensibility).
Location: Lines Bladder, Urethra, Ureters.
Transitional
Glandular Epithelium Tightly packed cells that specialize in
manufacturing and secreting products. Two categories:
Exocrine: Releases products into ducts.• sweat & oil glands, salivary, and mucus
glands. Endocrine: Releases products into
extracellular space (blood)• pituitary gland, thyroid gland, and adrenal
gland.
II. Connective Tissue Is composed of scattered loosely packed
cells that are within a large amount of nonliving intercellular material.
It is vascular Its primary function is to hold other
tissues and organs in place. Two categories of connective tissue
Produces & Maintains-(matrix) Protects From Infection (white blood cells)
Connective Tissue 4 Types of connective tissue
• A. Connective tissue proper• B. Cartilage• C. Bone• D. Blood forming (spongy bone)
A. Connective Tissue Proper Types of connective tissue proper:
Areolar, Adipose, Reticular, Dense Connective.
1. Areolar Tissue: AKA: Loose Connective Tissue. Contains fibroblast(producing cells) and
macrophages (protecting cells). Function: Anchors and cushions organs,
vessels, nerves. Fights bacteria. Stores lipids.
Areolar Tissue
A. Connective Tissue Proper 2. Adipose Tissue:
Contains adipocytes (producing cells which contain deposits of fat).
Function: Provides reserve energy, insulates & protects organs.
Adipose Tissue
A. Connective Tissue Proper
3. Dense Connective Tissue Two Types:
•Dense Regular- Fibers are arranged in parallel fashion. Extremely resistant to stress.
• tendons (muscle to bone)• ligaments (bone to bone)
•Dense Irregular- Fibers are arranged in an interwoven meshwork. Forms an external wrapping.
• Location: Wrapped around bone, cartilage, kidneys, liver, spleen, and where the tendon connects to the bone.
Dense Regular
Dense Irregular
A. Connective Tissue Proper 4.Reticular
Location: Lymphoid organs Function: Form a soft internal skeleton
to support other tissues.
Reticular Tissue
B. Cartilage Harder than connective tissue
proper. Contains chondrocytes (producing
cells). There are three types of cartilage:
Hyaline, Elastic, Fibrocartilage.
B. Cartilage 1. Hyaline Cartilage-
Bluish-white in color. Most abundant of all three. Function: Supports and reinforces,
with-stands compression. Location: Forms embryonic skeleton,
upper respiratory tract, costal cartilage, moveable joints.
Hyaline Cartilage
B. Cartilage 2. Elastic Cartilage
Yellowish in color. Function: Maintains shape allows for
flexibility. Location: Ears, Nose, Epiglottis.
Elastic Cartilage
B. Cartilage 3. Fibrocartilage
Has an abundance of collagen. Is found in association with hyaline
cartilage. Function: Shock absorber. Location:intervertebral disc, pubis
symphysis, knee joint.
Fibro Cartilage
C. Bone Has dense intercellular material
composed of mineral salts and collagenous fibers.
Made up of osteocytes Also known as osseous tissue. Two Types of BoneTwo Types of Bone
Compact and Spongy.
C. Bone Compact Bone: Forms the bones of
the skeletal system. Function: Provide structural support,
stores calcium. Location: All bones, the hard outside
layer of bone.
Bone (compact)
C. Bone Spongy Bone: Found inside of compact
bone. Has blood forming tissue called red marrow. Function: to produce blood cells. Location: inside the bone of the skeletal
system. Blood: is a type of connective tissue known
as formed elements.• Also know as liquid tissue• Has both solid (formed elements) and liquid
components.
Red Blood Cells
Spongy Bone
III. Muscle Tissue made of specialized cells that
contain protein filaments which allow the cells to contract.
The protein fibers are arranged in parallel bundles.
The Three types of muscle are: Skeletal, Smooth, and Cardiac.
A. Skeletal Muscle Striated (has bands of stripes). Multi-nucleated Attaches to bone, is the primary
mover in the muscular system. Voluntary (you control). Function: Body movement.
Skeletal Muscle
B. Smooth Muscle Not striated, Single Nucleus. In the walls of blood vessels and
visceral organs. Involuntary (not consciously
controlled). Function: Movement of: food, blood
urine, child birth etc.
Smooth Muscle
C. Cardiac Muscle Striated, Single Nucleus Contains thick cell membranes
called intercalated disks. Found in the walls of the heart. AKA myocardium. Involuntary. Function: move blood in the
circulatory system.
Cardiac Muscle
IV. Nervous Tissue Has well developed properties of
conductivity and excitability. Transmits electrochemical signals. Two Types of Nervous Tissue:
Neurons-Basic functioning unit of nervous tissue conducts electrochemical messages.
Neuroglia- Cells of the spinal cord and brain that maintain and support neurons.
Nervous Tissue