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)