Chapter 5Tissues

Intercellular Connections

• Individual cells connect to form tissues 3 ways:– Tight junctions-

– Desmosome- adhesion between cells in spots. Allows from some permeability.

– Gap junctions- cytoplasms of adjacent cells are connected through transport proteins. • Ions can pass freely through cells.

Intercellular Connections

Tissue TypesA tissue is a group of cells with a common

structure & functionThe human body is composed of four

main tissue types:

1. 2. Connective 3. 4. Nerve

Epithelial Tissue

Epithelial Tissue

Characteristics Always has a free (apical) surface

exposed to outside or open space. Has a basement membrane to

anchor underlying tissue

Functions Covers body surfaces Protects Absorbs Excretes

Classified by Shape Squamous – Cuboidal – Columnar –

Classified by ShapeMay occur in layers: Simple – Stratified – 2 or more layers Pseudostratified –

Example – simple cuboidal Example – stratified columnar

Examples of Epithelial Tissue

s

Simple Squamous- Thin, flattened cells. Allow for diffusion and filtration. Line air sacs of

lungs and walls of capillaries.

Simple cuboidal-single layer of cube shaped cells. Lines follicles of thyroid gland, kidneys and ducts of certain glands.

Simple columnar- single layer of elongated cells. Can contain cilia, used for protection and absorption in digestive tract.

Stratified squamous- Layers of squamous cells. Make up epidermis and line cavities exposed to external environment.

Stratified columnar- Several layers of columnar cells overlying cuboidal cells near the basement membrane.

Pseudostratified ciliated columnar- Appear stratified but are not. Often contain cilia and goblet cells which secrete mucus.

Pseudostratified ciliated columnarw/goblet cells- Line Respiratory passages to trap

unwanted particles

Transitional tissue- Changes in response to change in tension. Line urinary bladder and urethra.

Glandular Epithelium• Specialized to secrete substances•

• Those that secrete substances into ducts that open onto a surface are

• Those that secrete into tissues or blood are

Classifying Glands by Structure• Simple-

• Compound- duct that does branch before secretory portion.

Classifying Glands by Type of Secretions

3 types:

• • • Small portions of cells • in secretions• No loss of cytoplasm Ex. – mammary glands

in secretions• Ex. – pancreas

Classifying by Secretions

• Secretions w/entire cells filled w/secretoryproducts; ex. – sebaceous (oil) glands

Connective Tissue

Functions 1. connects 2. 3. protects 4. 5. fills spaces

Functions 6. stores fat 7. 8. protects against infection 9. 10.helps repair damaged tissue

Characteristics 1. Consists of cells in a matrix

(intercellular material) 2. Cells some distance apart 3. 4.

Types of Fibers:1. collagenous – composed of

collagen (protein); have great tensile strength; slightly elastic; compose bones, tendons & ligaments

Types of Fibers - continued

elastic – composed of elastin (protein); very elastic but weaker; compose vocal cords & air passages of lungs

Types of Fibers - continued Reticular – composed of very fine

collagenous fibers.

Types of Cells1. Fixed cells – stay in one place &

have stable numbers; 2 types:

fibroblasts – large & star-shaped; most prevalent

Types of Cells - continued mast cells – may release heparin

(for blood clotting) & histamines (promotes allergic reactions & inflammation); usually located near blood vessel walls

Types of Cells - continued2. Wandering cells – macrophages –

(Purple cells – macrophages, Green cells – T-lymphocytes)

Examples of Connective Tissue

Areolar tissue- binds the skin to underlying organs and under epithelium to provide bloodflow.

Adipose tissue- connective tissue composed of fats, cushion joints and provide insulation

Regular dense connective- strong fibers bind body parts together. Found in ligaments and tendons.

Irregular dense connective- disorganized and strong. Found in the dermis

Hyaline cartilage- Most common, found on ends of bones, nose cavity and supporting rings of resp. system.

Fibrocartilage- tough tissue containing collagenous fibers. Shock absorbers between vertebrae.

Elastic cartilage- flexible cartilage make up ears and larynx

Blood - platelets

Blood – red cells & white cell

Elastic connective

Reticular connective

Bone- A- central canal (contains blood vessels) B- Canaliculi- minute tubes allow for movement between cells.

Bone- D- Lamellae (layers of osetocytes), C- osteocytes

Muscle & Nerve Tissue

Muscle Tissue3 types: Skeletal-

Used for movement Smooth- lacks striations found in

skeletal, used for involuntary movements Ex- move food through digestive tract

Cardiac-

3 Types of Muscle Tissue

Smooth muscle- B- nucleus

Skeletal muscle- A- striations, B- nucleus

Cardiac muscle

Nervous Tissue

• Found in the brain, spinal cord and peripheral nerves.

• Cells called neurons–

• Also include neuroglia cells (support cells)– Support the function of the neurons

Nerve tissue – A- neuron, B- Axon, C- neuroglia