Body Tissue

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4 primary types of tissue, what are they?

• muscle

• nervous

• connective

• epithelial

epithelial tissue functions and locations

• locations

  • body coverings

  • body linings

• functions

  • protection

  • absorption

  • filtration

  • secretion

where does epithelial tissue line and cover?

covers and lines body surfaces, forms sheets with one free surface, the apical surface (top), an anchored surface, the basement membrane (bottom)

number of cell layers for simple and stratified

simple - one layer

stratified - more than one

different types of cell shapes

• squamous - flattened

• cubodial - cube-shaped

• columnar - shaped like columns

simple epithelial tissue function and density

• functions in secretion, absorption, and filtration

• very thin(one layer), not suited for protection

simple squamous epithelium

• single layer

• usually forms membranes

  • lines air sacs of lungs

  • forms walls of capillaries

  • forms serous membranes, the line and cover in ventral cavity

• functions in diffusion, filtration, or secretion in membranes

single cuboidal epithelium

• located in glands and their ducts

  • walls of kidney tubules

  • covers the surface of ovaries

• functions in secretion and adsorption like ciliated types propel mucus or reproductive cells

single columnar epithelium

• single layer of tall cells

• located in lining of digestive tract from the stomach to anus and mucous membranes line body cavities opening to the exterior

• function - secretion and absorption

* Pseudostratified columnar epithelium

• Location: respiratory tract, where it is ciliated and known as pseudo-stratified ciliated columnar epithelium

• Functions in absorption or secretion

Stratified epithelia

• consists of two or more cell layers

• function primarily in protection

Stratified squamous epithelium

• Functions as a protective covering where friction is common

• Locations—lining of the:

  • Skin (outer portion)

  • Mouth

  • Esophagus

Stratified cuboidal epithelium—

• two layers of cuboidal cells;

• functions in protection

Stratified columnar epithelium—

• surface cells are columnar, and cells underneath vary in size and shape;

• functions in protection

* Stratified cuboidal and columnar

• Rare in human body

• Found mainly in ducts of large glands

Transitional epithelium

• Composed of modified stratified squamous epithelium

• Shape of cells depends upon the amount of stretching

• Functions in stretching and the ability to return to normal shape

• Location: lining of urinary system organs

* Glandular epithelia

• One or more cells responsible for secreting a particular product

• Secretions contain protein molecules in an aqueous (water-based) fluid

• Secretion is an active process

Two major gland types develop from epithelial sheets

• Endocrine glands

  • Ductless; secretions (hormones) diffuse into blood vessels

  • Examples include thyroid, adrenals, and pituitary

• Exocrine glands

  • Secretions empty through ducts to the epithelial surface

  • Include sweat and oil glands, liver, and pancreas (both internal and external)

connective tissue

• Found everywhere in the body to connect body parts

• Includes the most abundant and widely distributed tissues

• Functions

  • Protection

  • Support

  • Binding

connective tissue variation blood supply

* Variations in blood supply
* Some tissue types are well vascularized
* Some have a poor blood supply or are avascular

what is extracellular matrix

nonliving material that surrounds living cells

Two main elements of the extracellular matrix

* Ground substance—mostly water, along with adhesion proteins and polysaccharide molecules
* Fibers
* Collagen (white) fibers
* Elastic (yellow) fibers
* Reticular fibers (a type of collagen)

Types of connective tissue from most rigid to softest, or most fluid:

• Bone

• Cartilage

• Dense connective tissue

• Loose connective tissue

• Blood

* Bone (osseous tissue)

• Composed of:

  • Osteocytes (bone cells) sitting in lacunae (cavities)

  • Hard matrix of calcium salts

  • Large numbers of collagen fibers

• Functions to protect and support the body

Cartilage

• Less hard and more flexible than bone

• Found in only a few places in the body

• Chondrocyte (cartilage cell) is the major cell type

• Types

  • Hyaline cartilage

  • Fibrocartilage

  • Elastic cartilage

Hyaline cartilage

• Most widespread type of cartilage

• Abundant collagen fibers hidden by a glassy, rubbery matrix

• Locations

  • Trachea

  • Attaches ribs to the breastbone

  • Covers ends of long bones

  • Entire fetal skeleton prior to birth

  • Epiphyseal (growth) plates in long bones

Elastic cartilage

• Provides elasticity

• Location: supports the external ear

Fibrocartilage

• Highly compressible

• Location: forms cushionlike discs between vertebrae of the spinal column

Dense connective tissue (dense fibrous tissue)

• Main matrix element is collagen fiber

• Fibroblasts are cells that make fibers

• Locations

  • Tendons—attach skeletal muscle to bone

  • Ligaments—attach bone to bone at joints and are more elastic than tendons

  • Dermis—lower layers of the skin

Loose connective tissue

• Softer, have more cells and fewer fibers than other connective tissues (except blood)

• Types

  • Areolar

  • Adipose

  • Reticular

Areolar connective tissue

• Functions as a universal packing tissue and “glue” to hold organs in place

• Layer of areolar tissue called lamina propria underlies all membranes

• All fiber types form a loose network

• Can soak up excess fluid (causes edema)

Adipose connective tissue

• Functions

  • Insulates the body

  • Protects some organs

  • Serves as a site of fuel storage

• Locations

  • Subcutaneous tissue beneath the skin

  • Protects organs, such as the kidneys

  • Fat “depots” include hips, breasts, and belly

Reticular connective tissue

• Forms stroma (internal framework) of organs

• Locations

  • Lymph nodes

  • Spleen

  • Bone marrow

Blood (vascular tissue)

• Blood cells surrounded by fluid matrix known as blood plasma

• Functions as the transport vehicle for the cardiovascular system, carrying:

  • Nutrients

  • Wastes

  • Respiratory gases

muscle tissue

• function is to contract, or shorten, to produce movement

• Three types of muscle tissue

  1. Skeletal

  2. Cardiac

  3. Smooth

Skeletal muscle tissue

• Packaged by connective tissue sheets into skeletal muscles, which are attached to the skeleton and pull on bones or skin

• Voluntarily (consciously) controlled

• Produces gross body movements or facial expressions

• Characteristics of skeletal muscle cells

  • Striations (stripes)

  • Multinucleate (more than one nucleus)

  • Long, cylindrical shape

Cardiac muscle tissue

• Involuntarily controlled

• Found only in the heart

• Pumps blood through blood vessels

• Characteristics of cardiac muscle cells

  • Striations

  • One nucleus per cell

  • Short, branching cells

  • Intercalated discs contain gap junctions to connect cells together

Smooth (visceral) muscle tissue

• Involuntarily controlled

• Found in walls of hollow organs such as stomach, uterus, and blood vessels

• Peristalsis, a wavelike activity, is a typical activity

• Characteristics of smooth muscle cells

  • No visible striations

  • One nucleus per cell

  • Spindle-shaped cells

Nervous Tissue

• Function is to receive and conduct electrochemical impulses to and from body parts

  • Irritability

  • Conductivity

• Composed of neurons and nerve support cells

Support cells called neuroglia insulate, protect, and support neurons

what are the shapes for squamous, cuboidal, and columnar?

• squamous - flattened

• cubodial, cube shaped

• columnar - shaped like columns