Tissue Level of OrganizationHistology
McKinley and O’Laughlin
Chapter 4
Introduction
What is an aggregation of cells of similar structure and function? Tissue
Introduction
What is a tissue? Organized groups of similar cells, and
extracellular products, that carry out a common function
Introduction
What do we call the study of tissues? Histology
How many primary tissue types are there? 4
Introduction
List the 4 primary tissue types. Epithelial tissue Connective tissue Muscle tissue Nervous tissue
4 Primary Tissue Types
Epithelial Tissue Covers surfaces Lines organs and
body cavities Forms glands
4 Primary Tissue Types
Connective Tissue Supports Protects Binds
4 Primary Tissue Types
Muscle Tissue Contracts
4 Primary Tissue Types
Nervous Tissue Generates,
transmits, and receives impulses
Supports and protects neurons
What primary tissue type acts as a covering or lining? Epithelial tissue
Epithelial Tissue
List 6 characteristics of epithelial tissue. Cellularity – little extracellular matrix Polarity – apical and basal surfaces Attachment – basement membrane Avascularity – underlying connective tissue
vascular
Epithelial Tissue
List 6 characteristics of epithelial tissue. Cellularity Polarity Attachment Avascularity Innervation – along with underlying
connective tissue High regeneration capacity – stem cells
Epithelial Tissue
List the functions of epithelial tissue? Physical protection Selective permeability Secretions Sensations
Epithelial Tissue
What are the 2 major categories of epithelial tissue? Membranous epithelia Glandular epithelia
Characteristics of Membranous Epithelia
One side of membranous epithelia is always exposed to what? Free surface or lumen
What is the other side attached to? Basement membrane
Classification of Membranous Epithelia
What 2 factors are used to classify epithelia? Layering or stratification Shape of apical cells
Classification of Membranous Epithelia
What are 3 classifications of epithelium based on cell layers? Simple Stratified Pseudostratified
Classification of Membranous Epithelia
What are classifications of epithelium based on shape? Squamous Cuboidal Columnar Transitional
Change appearance depending on stretching of epithelia
Types of Epithelium
What type of epithelium consists of a single layer of flattened cells? Simple squamous epithelium
Types of Epithelium
In general, where is simple squamous epithelium found? Protected regions
Alveoli Endothelium Mesothelium
Types of Epithelium
What type of epithelium consists of a single layer of cells that are as tall as they are wide? Simple Cuboidal
Types of Epithelium
Where is this type (simple cuboidal) of epithelium found? Walls of kidney tubules Ducts of exocrine glands Ovarian surface Thyroid follicles
Types of Epithelium
What type of epithelium is composed of a single layer of tall, narrow cells? Simple columnar epithelium
Types of Epithelium
What are the general functions of this type of epithelium? Absorption Secretion
Types of Epithelium
What are the 2 general types of epithelium composed of a single layer of cells that are taller than wide? Ciliated Non-ciliated
Types of Epithelium
Where is the only place in the body that the ciliated form occurs (Pseudostratified is technically simple, but we aren’t addressing it here)? Uterine tubes (lining)
Types of Epithelium
Non-ciliated (simple columnar epithelia) often have what finger-like projections? Microvilli
Types of Epithelium
What is the purpose of these structures (microvilli)? Increase surface area
Absorption
Types of Epithelium
What unicellular glands occur within it (Simple columnar epithelia)? Goblet cells
What do these cells secrete? Mucus
Types of Epithelium
What type of epithelium is composed of multiple layers with the apical layer being flat? Stratified squamous epithelium
Types of Epithelium
What are the functions (of stratified squamous epithelium)? Protection
Types of Epithelium
What 2 general types (of stratified squamous epithelium) occur? Keratinized Non-keratinized
Types of Epithelium
Define each and list some locations where they occur. Keratinized: apical layers dead, contain the
protein keratin Waterproofing and strengthening Epidermis
Non-keratinized: apical layers living, moistened with mucus Mouth, pharynx, esophagus, vagina, anus
Types of Epithelium
What type of epithelium is typically composed of two layers with the apical layer being cube-shaped cells? Stratified cuboidal epithelium
Types of Epithelium
What is the main function of this type (stratified cuboidal) epithelium? Protection
Secretion: by providing a path for secreted products
Types of Epithelium
Where is it (stratified cuboidal epithelium) found? Larger ducts of exocrine glands
E.g. salivary and sudoriferous glands Part of the male urethra
Types of Epithelium
What type of epithelium is composed of two or more layers of cells with the apical layer made of cells taller than they are wide? Stratified columnar epithelium
Types of Epithelium
What is the function of this type (stratified columnar epithelium)? Protection
Secretion: by providing a path for secreted products
E.g. same as stratified cuboidal epithelium
Types of Epithelium
Where is it (stratified columnar epithelium) found? Larger ducts of exocrine glands
E.g. salivary and sudoriferous glands Part of the male urethra
E.g. same as stratified cuboidal epithelium
Types of Epithelium
What type of epithelium appears to be layered but is not? Pseudostratified epithelium
Types of Epithelium
What 2 types (of pseudostratified epithelium) occur? Ciliated Non-ciliated
Types of Epithelium
Where are they found? Ciliated: respiratory tract (large tubes) Non-ciliated: male urethra and epididymis
Types of Epithelium
What type of epithelium may be stretched? Transitional epithelium
Types of Epithelium
Where does it (transitional epithelium) occur? Bladder Ureters Urethra
Types of Epithelium
Glands arise from epithelial tissue invaginating into what type of underlying tissue? Connective tissue
Types of Epithelium
What is the function of a gland? Secretion
Types of Epithelium
List and define the 2 general types of glands? Endocrine: lack ducts, secrete directly into
blood and interstitial fluid Exocrine: duct connects secretory cells to
surface
Connective Tissue
What is connective tissue? Diverse tissues that bind, support, and protect Characterized by extensive extracellular matrix
Connective Tissue
What are the 3 basic components of connective tissue? Cells Protein fibers Ground substance
Connective Tissue
What is the extracellular matrix of connective tissue? Ground substance Protein fibers Gives the connective tissue its properties
Connective Tissue
List the main functions of connective tissue? Physical protection Support (and structural framework) Binding (of structures) Storage - fat Transport - blood Immunity - interferes with movement of
invaders and houses leukocytes
Connective Tissue
From which of the primary germ layers does connective tissue arise? Mesoderm
Connective Tissue
Connective tissue may be classified into what 3 broad categories? Connective tissue proper Supporting connective tissue Fluid connective tissue
Connective Tissue
What are the 2 broad categories of connective tissue proper? Loose Dense
Connective Tissue
What type of loose connective tissue surrounds nerves, blood vessels, and individual muscle cells? Areolar connective tissue
Also found in superficial dermis
Connective Tissue
This type of tissue forms shiny layers of binding tissue commonly known as what? Fascia
Superficial
Connective Tissue
What type of loose connective tissue is commonly known as “fat”? Adipose connective tissue
Connective Tissue
What type of connective tissue forms a meshwork that acts as a structural framework for organs such as the spleen, thymus, and lymph nodes? Reticular connective tissue
Connective Tissue
What are the 3 types of dense connective tissue? Dense regular connective tissue Dense irregular connective tissue Elastic connective tissue
Connective Tissue
What type of dense connective tissue is composed of densely-packed, parallel collagen fibers? Dense regular connective tissue
Connective Tissue
Where is it (dense regular connective tissue) found? Tendons Ligaments
Connective Tissue
What type of dense connective tissue is composed of collagen fibers extending in all directions? Dense irregular connective tissue
Connective Tissue
Where is it (dense irregular connective tissue) found? Dermis
Deep
Perichondrium Periosteum Joint capsules
Connective Tissue
What type of dense connective tissue contains elastic fibers? Elastic connective tissue
Connective Tissue
What are the 2 types of supporting connective tissue? Cartilage Bone
Connective Tissue
Which of these 2 is more flexible and found where the body needs support and must withstand deformation? Cartilage
Connective Tissue
What is the most common type of cartilage? Hyaline cartilage
Connective Tissue
Where is it (hyaline cartilage) found? Articular surfaces of long bones Nose Trachea Larynx Costal cartilage Fetal skeleton Epiphyseal plates
Connective Tissue
What type of cartilage has numerous coarse, readily visible fibers arranged in irregular bundles between large chondrocytes? Fibrocartilage
Connective Tissue
Where is it (fibrocartilage) found? Intervertebral discs Pubic symphysis Menisci
Connective Tissue
What type of cartilage contains numerous elastic fibers? Elastic cartilage
Connective Tissue
Where is it (elastic cartilage) found? Epiglottis External ear
Connective Tissue
What type of connective tissue is composed of 1/3 organic components and 2/3 calcium salts? Bone
Primarily calcium phosphate
Connective Tissue
What dense irregular connective tissue covers almost all bone surfaces? Periosteum
Connective Tissue
There are 2 forms of bone. Which is solid and forms the outer shell of an individual bone? Cortical bone (compact)
Connective Tissue
There are 2 forms of bone. Which type of bone forms a latticework inside of individual bones? Cancellous bone (spongy)
Connective Tissue
What is the fluid connective tissue? Blood
Connective Tissue
List and give the function of the formed elements of blood. Erythrocytes: transport oxygen Leukocytes: immunity Thrombocytes (platelets): clotting
Connective Tissue
What is the liquid portion of blood? Plasma: transports nutrients, wastes, hormones
Matrix Most of the carbon dioxide is transferred here as
carbonic acid
Body Membranes
What type of membrane lines passageways and compartments that open to the exterior? Mucous membranes (mucosa)
Body Membranes
What type of membrane lines enclosed cavities and produces a thin, watery fluid? Serous membranes (serosa)
Body Membranes
These membranes (serosa) have what 2 parts? Parietal part Visceral part
Body Membranes
What is the largest membrane of the body? Cutaneous membrane (skin)
Body Membranes
What type of membrane lines the capsules of freely moving joints? Synovial membranes
Muscle Tissue
What type of muscle tissue has long fibers that are striated, multinucleated, and voluntary? Skeletal muscle
Muscle Tissue
What type of muscle tissue has short, branched fibers with one or two central nuclei, striations, and intercalated discs (also, it is involuntary)? Cardiac muscle
Muscle Tissue
What type of muscle tissue has short, fusiform, non-striated fibers and is involuntary? Smooth muscle
Nervous Tissue
What type of cells within neural tissue are specialized to detect stimuli, process information, and rapidly transmit electrical impulses? Neurons
Longest cells in the body (because of the length of the axon)
Nervous Tissue
What are the three main parts of these cells (neurons)? Cell body (soma) Dendrites - incoming Axon - outgoing
Nervous Tissue
What type of cells within neural tissue specialize in supporting, protecting, and providing a framework for others? Glial cells (neuroglia)