Anatomy and Physiology I

Tissue Types

Key Terms

Histology: the study of tissues.

Tissues: groups of cells which are similar in

structure and which perform common or related functions.

Four Basic Kinds of Tissues

Epithelial TissueConnective TissueMuscle TissueNervous Tissue

Epithelial Tissue

Epithelial Tissue Locations: Covers the body Lines the cavities, tubes, ducts and blood

vessels inside the body Covers the organs inside body cavities

Epithelial Tissue Functions: Protection from physical & chemical injury, Protection against microbial invasion, Contains receptors which respond to stimuli, Filters, secretes & reabsorbs materials and Secretes serous fluids to lubricate structures.

Examples of Epithelium Tissue Lines the respiratory tract Lines the digestive system Skin Surrounding internal organs

Characteristics of Epithelium Tissue1. Cells are tightly packed2. Regenerate easily3. Avascular – lack blood vessels4. apical surface – exposed surface5. Basement membrane – anchors down

cells

Connective Tissue

Connective Tissue: Most abundant & widely distributed

tissue Connective Tissue Functions:

Connects, binds and supports structures,

Tendons, ligaments, etc. Protects & cushions organs and tissues, Insulates (fat) and Transports substances (blood).

Examples of Connective Tissue Bones Cartilage Tendons Blood Fat

Characteristics of Connective Tissue1. Most are well vascularized – have a good

blood supply2. Some have very poor blood supply being

avascular.3. Extracellular matrix – nonliving substance

found outside the cells

Extracellular Matrix explained

Nonliving material between cells Produced by the cells and then

extruded Responsible for the strength Two components

1. Ground substance Of fluid, adhesion proteins, proteoglycans Liquid, semisolid, gel-like or very hard

2. Fibers: collagen, elastic or reticular

Epithelial Tissue in Detail

Classification of epithelia

According to thickness “simple” - one cell layer “stratified” – more than one layer of

cells (which are named according to the shape of the cells in the apical(base) layer)

According to shape “squamous” – wider than tall “cuboidal” – as tall as wide “columnar” - taller than wide

Human Anatomy, Larry M. Frolich, Ph.D.

Simple: just one layer or cell shape

Stratified: multiple layers and cell shapes

Classes of Epithelia

Human Anatomy, Larry M. Frolich, Ph.D.

Simple Epithelia

Type

Cell shape Example

Squamous Squashed Endothelium (lines blood vessels), mesothelium (serous lining of celom)

Cuboidal

Cubed Walls of glands

Columnar Columns Lining of gut tube; sometimes with cilia like lining of uterine tube

Pseudo-stratified Flat cells give rise to columns

With cilia in respiratory tubes to move mucous/particles out of lungs

to protect

where diffusion is important

where tissues are involved in secretion and absorption: larger cells because of the machinery of production, packaging, and energy requirements

Simple Squamous Epithelium

Descriptions: Single layer, flattened cells, simplest of

epithelia Function:

Allows passage of materials by diffusion and filtration

Secretes lubricating substances Location:

Air sacs of lungs, lining of heart, blood vessels, lining of ventral body cavity

Simple Cuboidal epithelium

Descriptions: Single layered, cube like, large spherical

central nuclei Function:

Secretion and absorption Location:

Kidney tubules, ovary surfaces

“ciliated” literally = eyelashes(see next page)

Simple Columnar Epithelium Descriptions:

Single layer, tall, round or oval nuclei, some bear cilia,

may contain mucus-secreting glands(goblet cells)

Function: Absorption, secretion of mucus and

enzymes, cilia propels mucus Location:

Nonciliated lines the digestive tract Ciliated lines small bronchi, uterine tubes,

parts of uterus.

Pseudostratified Columnar Epithelium

Descriptions: Single layer w/ differing heights, nuclei at

different levels, may have goblet cells or cilia

Function: Secretion(especially mucus), propulsion of

mucus by ciliary action Location:

Nonciliated in sperm carrying ducts Ciliated lines the trachea and upper

respiratory tract.

Stratified: regenerate from below

Stratified Squamous Epithelium

Descriptions: (most common stratified) Several layers, surface cells are squamous,

basal cells are cuboidal or columnar Function:

Protects underlying tissues in areas of abrasion

Location: Esophagus, the mouth, outer portion of

skin

Rare…

Stratified Cuboidal Epithelium

Descriptions: (rare) Usually two layers of cube-like cells

Function: Protection

Location: Rare Largest ducts of sweat glands,

mammary glands, and salivary glands.

Rare…

Stratified Columnar Epithelium

Descriptions: (rare) Several layers thick, columnar with

varying in size and shape Function:

Protection, secretion Location:

Rare Large ducts of glands

Transitional Epithelium

Descriptions: Highly modified, several layers of

cuboidal or columnar cells Function:

Stretches readily, allowing distention of urinary organs

Location: Lines the ureters, bladder, parts of

urethra

Human Anatomy, Larry M. Frolich, Ph.D.

Human Anatomy, Larry M. Frolich, Ph.D.

Can You Identify the Classes of Epithelium?

A B

C

D

EQuiz!!

Specific Connective Tissue In Detail

Bone

Descriptions: Aka: osseous tissue Hard calcified matrix, surrounded by layers

of calcium salts in additions to lots of collagen fibers

Cells sit in cavities called “lacunae” Function:

Protection and support Location:

Skeletal system

Hyaline Cartilage

Descriptions: (hyalin=glass) Most common and widespread type Collagen fibers with a rubbery matrix

Function: Supports/reinforces, resilient cushioning

Location: Covers ends of bones in joints, nose,

trachea, larynx, embryonic skeleton

Elastic Cartilage

Descriptions: Collagen fibers with a rubbery matrix Very elastic

Function: Maintains shape of structure gives flexibility

Location: External ear epiglottis

Fibrocartilage

Descriptions: Similar to hyaline but less firm Much like a cushion

Function: Absorbs compressive shock

Location: Intervertebral discs, discs of knee joint

Dense Connective Tissue

Descriptions: Collagen fibers, fibroblasts fill gaps

between collagen Strong ropelike structures like tendons

and ligaments Function:

Connect muscles to bones, connect bones at joints, lots of tensile strength

Location: joints

Vocab Fibroblasts – cells that make collagen

fibers Tendons – attach skeletal muscles to

bones Ligaments - connect bones to bones at

joints. More stretchy and contain more elastic fibers than tendon

Loose CT: Areolar Tissue

Descriptions: Gel-like matrix w/ all three fiber types Very loose network w/ lots of open space

Function: Wraps and cushions organs, a reservoir of

water and salts for surrounding tissues, important for swelling

Location: Under epithelia, around organs, surrounds

capillaries

Loose CT: Adipose Tissue

Descriptions: (fat) Very similar to areolar tissue Fat cells predominate

Function: Insulates against heat loss, supports and

protects organs, reserve food fuel Location:

Under skin, around kidneys and eyeballs, abdomen and breast

Loose CT: Reticular CT

Descriptions: Network of reticular fibers (similar to

fibroblast) Delicate network of interwoven fibers

Function: Form soft internal skeleton that supports

other cells such as white blood cells, mast cells

Location: Lymphoid organs (lymph nodes, bone

marrow, spleen)

Blood

Descriptions: (vascular tissue) Red and white blood cells in a fluid

matrix (plasma) Fibers are soluble only seen during

clotting Function:

Transportation of gases, nutrients, wastes ect.

Location: Everywhere

Muscle Tissue Muscle Tissue:

Associated with the bones of the skeleton, the heart and in the walls of the hollow organs of the body.

Made to contract Called muscle fibers because they are elongated to

provide a long axis for contraction Muscle Tissue Functions:

Movement Maintains posture Produces heat Facial expressions Pumps blood Peristalsis

Specific Muscle Tissue Types: skeletal muscle Cardiac muscle Smooth muscle

Skeletal Muscle

Descriptions: Long, cylindrical, obvious striations,

multinucleated Function:

Voluntary movement, manipulation of the environment, facial expression

Gross body movement Location:

Attached to bones

Cardiac Muscle

Descriptions: Branching, striated, uninucleated cells

that fit tightly together at junctions called “intercalated disks”

Function: Involuntary control, propels blood into

circulation. Location:

Walls of the heart

Smooth Muscle

Descriptions: (visceral) No striations, spindle-shaped w/ central

nuclei Arranged closely to form sheets

Function: Propelles substances along internal

passageways, involuntary control Peristalsis – wavelike motion

Location: Walls of the stomach, bladder, uterus and

blood vessels

Nervous Tissue

Nervous Tissue: Main component of the nervous system,

ie., brain, spinal cord & nerves.

Nervous Tissue Functions: Regulates & controls body functions Generates & transmits nerve impulses Supports, insulates and protects

impulse generating neurons.

Nervous Tissue

Descriptions: (Neurons) Branching cells, has long extended parts Irritability and conductivity Have “supporting cells” that insulate,

support and protect neurons. Function:

Transmits electrical signals from sensory receptors to effectors that control their activity

Location: Brain, Spinal cord and nerves

Muscle - Skeletal Muscle fibers (cells)

long, parallel & cylindrical

With many nuclei (multinucleate)

Striations (cross stripes run perpendicular to the cells

Produce voluntary movement

Locomotion Heat

Specific Nervous Tissue Types Nervous – Neuron

Branching cells with many long processes

Large central nucleus

Transmit impulses from one area of the body to other areas

Regulate activities through neuron impulses