Unit 2: Tissues

What is a tissue?

A group or mass of similar cells working together to perform common functions

What are the four major types of tissues?

1. Epithelial

2. Connective

3. Muscle

4. Nervous

Epithelial Tissue

• Covers all body surfaces both inside and out

• Main glandular tissue

• Attached to underlying connective tissue at the basement membrane

• Usually has no vascular tissue - no blood supply

• Cells reproduce rapidly, resulting in rapid healing and scarring'

• Cells tightly pack together

Function

Protection, secretion, absorption, excretion, senses

Simple Squamos

Form

Flat and thin, single layer

Function

Secretion, diffusion, and filtration

Location

Found in air sacs of the lungs, and in capillaries

Simple Cuboidal

Form

Single-layer, cube-shaped cells

Function

Secretion and absorption

Location

Lining of kidney tubules, covering the surface of ovaries

Simple Columnar

Form

Single Layer, long cells

Function

Secretion and absorption

Location

Digestive tract and uterus

Stratified Squamos

Form

Flat and thin, multiple layers

Function

Protection

Location

Around body cavities, skin, and mouth

Stratified Cuboidal

Form

Multiple layers, cube-shaped cells

Function

Provides protection and aids secretion

Location

Glandular regions and male urethra

Stratified Columnar

Form

Multiple layers, long cells

Function

Protection and secretion

Location

Eye, male urethra, anus, pharynx

Pseudostratified Columnar

Form

• Single layer with nuclei at various levels giving the appearance of layered cells

• Can have cilia and goblet cells

Function

Secretion, and cilia-aided movement

Location

Lining air passages like the trachea, tubes of the reproductive system

Transitional Epithelium

Form

Thick, layered cuboidal cells (stretchable)

Function

Forms a barrier to block diffusion

Location

Urinary bladder

Glandular Epithelium

Cells specialized to secrete substances. They make up the body’s glands

Epidermis

The thin, outermost layer of the skin that you can see and touch

Basement Membrane

a thin, dense sheet of specialized extracellular matrix that separates cell layers like epithelium and endothelium from underlying connective tissue

Melanocytes

specialized cells in the outer layer of your skin, hair, and eyes that make melanin

Dermis

thick middle layer of skin located directly beneath the epidermis and above the subcutaneous hypodermis layer

Connective Tissue

• Most abundant tissue in your body

• Provides support, protection, framework, fill space

• Stores fat, produces blood cells, and fights infection

• Composed of scattered cells within a matrix

• Made up of ground substance and fibers

• Most have a good blood supply

Three common types of connective tissue

1. Mast Cells

2. Macrophages

3. Fibroblasts

Collagenous Fibers

Traits

Strong, flexible, not very elastic

Location

Bones, ligaments, tendons

Elastic Fibers

Traits

Not as strong, but very elastic

Location

Ears, and vocal cords

Loose C. T. or Areolar Tissue

• Binds skin to underlying organs and organs to organs

• Forms thin membranes throughout the body

Adipose Tissue

• Fat beneath the skin

• protective cushion, insulation to preserve body head

• stores energy

Fibrous Connective Tissue

• Thick collagenous fibers and elastic fibers.

• Few cells, poor blood supply, slow healing

• Tendons = Muscles to Bone

• Ligaments = bone to Bone

Cartilage

• Chondrocytes

• Hyaline Cartilage: Covers ends of joints

• Elastic Cartilage: External ear and larynx

• Fibrocartilage: Between vertebrae

Bone Tissue

Osseous tissue. Rigid due to mineral salts

Blood Tissue

Circulates throughout the body

Muscle Tissue

• Skeletal: Voluntary (Striated)

• Smooth: In hollow organs

• Stomach: Involuntary

• Cardiac: Wall of the heart

Nervous Tissue

Found in brain, spinal cord, and nerves

Neurons

Transmit signals

Neuroglia

Protect and support neurons

Mast Cells

Prevent Clots

Macrophages

White blood cells that consume pathogens, foreign substances, and cellular debris

Fibroplasts

Produce Fibers