Warm-Up

1. What is a tissue?2. The study of tissues is called ______.3. What are the 4 main types of

tissues?

Warm-UpWhat type of epithelial cell is shown below?

1. 2.

3.

4.

Simple Columnar Epithelium

Stratified Squamous Epithelium

Pseudostratified Columnar Epithelium

Simple Cuboidal Epithelium

Chapter 4

Tissue: group of cells that are similar in structure and function

Histology: study of tissues

Types of Tissues:1. Epithelium (covering)2. Connective (support)3. Muscle (movement)4. Nervous (control)

Preparing tissues for microscopy

Specimen is fixed (preserved) Cut into thin sections (slices) Stained with colored dyes

Part I: Epithelial Tissue

Epithelial Tissue

“epithe” = laid on, covering Structure:

1. Covering and lining epithelium2. Glandular epithelium

Function: Protection Absorption Filtration Secretion

Special Properties1. Polarity

Apical surface = exposed free surface or edge (some with microvilli, cilia)

Basal surface = lower, attached surface

2. Specialized contacts Fits close together to form continuous

sheets

Special Properties3. Supported by connective tissue

Rests on basement membrane 4. No blood supply (avascular)

Rely on diffusion and underlying connective tissue for food/O2

5. Regeneration – Replace lost cells

Classification Two names = (# cell layers) + (shape of cells) Cell Layers: simple or stratified Shapes: squamous, cuboidal, or columnar

Simple Epithelium

Absorption, secretion, filtration Very thin

Simple Epithelium

Simple Epithelium

Simple squamous Filtration, rapid diffusion Capillary walls, air sacs in lungs, kidney

filtration Serous membranes: slick layer lining

ventral body cavity and its organs

Simple Epithelium Simple cuboidal

Secretion & absorption Lines ducts of glands (salivary), kidney

tubules, ovary surface

Simple Epithelium

Simple columnar Absorption and

secretion Lines digestive tract Microvilli, cilia Mucous

membranes: lubricating mucus

Simple Epithelium

Pseudostratified columnar Rests on basement membrane – false

impression (pseudo) of being multi-layered

Secretes or absorbs Respiratory tract – cilia propels mucus

from lungs

Stratified Epithelium

2+ layers, more durable Main function = protect

Stratified Epithelium

Stratified squamous Withstand abuse, friction Esophagus, mouth, outer portion of skin

Stratified Epithelium

Stratified cuboidal Usually 2 layers Mainly in ducts of large glands (sweat,

mammary, salivary)

Sweat Gland Esophageal Gland

Stratified Epithelium

Stratified columnar Thick, waterproof layer Pharynx, male urethra, lining ducts

Transitional Epithelium

Able to change shape (cuboidal squamous)

Lining of hollow urinary organs (bladder, ureter, urethra)

Stretches when filled with urine

Glandular Epithelium

Gland: make and secrete a particular product

2 Types: Endocrine gland: produce hormones

secreted into tissue fluid or bloodstream

Exocrine gland: secrete products into ducts onto body surfaces or body cavities Eg. mucous, sweat, oil, saliva, bile

Exocrine Glands

Unicellular Multicellular Mucus cells or

goblet cells Duct structure

Warm-UpWhat type of connective tissue is shown below?

1. 2.

3. 4.

Cartilage

Blood

Adipose Tissue (Loose

Connective Tissue)

Bone

Chapter 4

Part II: Connective Tissue

Connective Tissue Most abundant and widely distributed tissue Main classes:

1. Connective tissue proper (loose & dense)2. Cartilage3. Bone4. Blood

Functions:1. Binding and support2. Protection3. Insulation4. Transport substances

Classification Variations in blood supply

Avascular (no blood) – cartilage Poorly vascular – tendons, ligaments

Extracellular matrix Produced by cells, secreted to exterior Ground substance: “glue” - fills space

between cells & fibers water + adhesion proteins + polysaccharides

Fibers: provide support Collagen - strength Elastic – stretch Reticular – fine network, “skeleton” of organs

Loose Connective Tissue Universal packing material Subclasses: areolar, adipose, reticular Structure: softer, fewer fibers, gel-like

matrix Functions:

Cushion & protect organs (areolar, fat) Store nutrients (fat) Internal framework (reticular) Fight infection (areolar)

Cells: fibroblasts, adipocytes (fat cells) Locations: under skin, lymph nodes, hips,

behind eyeballs

Dense Connective Tissue

Tendons & ligaments Subclasses: dense regular, dense

irregular, elastic Structure: mainly collagen fibers Functions:

Elastic Resist tension

Cells: fibroblasts Locations: tendons (muscle-bone),

ligaments (bone-bone), lower layers of skin

Cartilage

Subclasses: hyaline, elastic, fibrocartilage

Structure: flexible, no nerves or blood Functions:

Support Compression

Cells: chondroblasts, chondrocytes Locations: larynx, joints, tip of nose,

ear, intervertebral discs, rib-breastbone, knee joint

Bone

Osseous tissue Subclasses: compact, spongy Structure: hard, calcified matrix;

blood vessels Functions:

support & protect Store calcium Blood cell formation (marrow)

Cells: osteoblasts, osteocytes Locations: bones

Blood

Vascular tissue Subclasses: blood cells, plasma Structure: fluid within blood vessels,

no fibers Functions:

Transport vehicle (nutrients, wastes, gases, hormones)

Cells: white blood cells (leukocytes), red blood cells (erythrocytes), platelets

Locations: blood vessels

Part III: Muscle Tissue

3 types: Skeletal muscle Cardiac muscle Smooth muscle

Skeletal Muscle Description:

Long, cylindrical Multinucleate (2+ nuclei) Striated (banded appearance)

Function: Muscles contract, pull on bones or skin

cause body movements Location in the body:

Attached to skeleton Other features:

Voluntary control

Cardiac Muscle Description:

Striated Uninucleate (1 nucleus) Branching cells – fit at junctions called intercalated

discs Function:

Propel blood through blood vessels to all parts of body

Locations in the body: Walls of the heart

Other features: Involuntary control

Smooth Muscle Description:

No visible striations 1 central nucleus Spindle-shaped (pointed ends)

Function: Propel substances through hollow organs

Locations in the body: Walls of organs (stomach, bladder, uterus, blood vessels)

Other features: Involuntary control Contracts slowly Peristalsis: wavelike motion that moves food through SI

Part IV: Nervous Tissue Main component of nervous system Structure: neuron = dendrite + cell

body + axon Function: regulates and controls body

functions Location in the body: brain, spinal

cord, nerves

Part IV: Nervous Tissue 2 Major Cell Types:

Neurons Respond to stimuli Transmit electrical impulses

Other cells Support, insulate, protect neurons

Tissue Repair

Wound healing Two ways:

1. Regeneration: replace destroyed tissue by same kind of cells

2. Fibrosis: form scar tissue (dense fibrous connective tissue)

Depends on: Type of tissue damaged Severity of injury

Steps to Tissue Repair:

1. Inflammation Capillaries become very permeable WBC’s and clotting proteins seep into

injured area Clot prevents loss of blood (surface dries,

forms a scab)

Steps to Tissue Repair:

2. Granulation tissue forms Delicate pink tissue with new capillaries Connective tissue produces collagen

fibers Epithelial cells multiply over granulation

tissue

Steps to Tissue Repair:

3. Surface epithelium regenerates Surface epithelium thickens Fibrous tissue matures – forms scar

tissue

Regenerative Capacity of Different Tissues

Extremely Well

Moderate

Weak

Virtually None

(mostly scar

tissue)• Skin epidermis

• Mucous membranes

• Fibrous connective

• Blood• Bones

• Smooth muscle

• Tendons, ligaments

• Skeletal muscle

• Cartilage

•Cardiac muscle

•Nervous tissue