Chapter 5 Tissues

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 Types A tissue is a group of cells with a common structure & function The human body is composed of four main tissue types: Connective Nerve

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 Shape May 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 columnar w/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/secretory products; ex. – sebaceous (oil) glands

Connective Tissue

Functions 1.connects protects 4. 5.fills spaces

Functions 6. stores fat protects against infection 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 Cells 1. 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 - continued 2. 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 Tissue 3 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