chapter 5 tissues. intercellular connections individual cells connect to form tissues 3 ways:...

Chapter 5Tissues

Intercellular Connections

• Individual cells connect to form tissues 3 ways:– Tight junctions- prevents permeability of ions

through junction.– 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:

1. Epithelial 2. Connective 3. Muscle 4. Nerve

Epithelial Tissue

Epithelial Tissue

Characteristics

Always has a free (apical) surface exposed to outside or open space.

Lacks blood vessels Readily divide and replicate Has a basement membrane to

anchor underlying tissue Between epithelial and connective

tissue

Functions

Covers body surfaces Makes up glands Protects Absorbs Secretes Excretes

Classified by Shape

Squamous – flattened cells Cuboidal – cube-shaped Columnar – tall, column-shaped

Classified by Shape

May occur in layers: Simple – 1 layer of cells Stratified – 2 or more layers Pseudostratified – appears to be

layered, but is not 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. Used for secretion and absorption

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

Stratified squamous- Layers of squamous cells. Make up epidermis and line cavities exposed to external environment. Outer layer die and accumulate keratin.

Stratified columnar- Several layers of columnar cells overlying cuboidal cells near the

basement membrane. Found in male reprod. System and pharynx

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

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

unwanted particles

Transitional tissue- Changes in response to change in tension (stretching). Line urinary bladder and urethra. Larger cells at surface, smaller cells deeper.

Glandular Epithelium

• Specialized to secrete substances• Usually glands are lined w/cuboidal or

columnar epithelium• Those that secrete substances into ducts

that open onto a surface are exocrine glands (salivary, oil glands, etc.)

• Those that secrete into tissues or blood are endocrine glands (pituitary)

Classifying Glands by Structure

• Simple- does not branch off before reaching secretory portion

• 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. supports 3. protects 4. provides framework 5. fills spaces

Functions

6. stores fat 7. produces blood cells 8. protects against infection 9. transports nutrients 10.helps repair damaged tissue

Characteristics

1. Consists of cells in a matrix (intercellular material)

2. Cells some distance apart 3. Most can divide 4. Good blood supply

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.

Form support network.

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 –

travel through body; numbers change in response to infection; scavengers

(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. Binds and protects. A- fibroblast, B-collagen, C- elastin

Adipose tissue- connective tissue composed of fats, cushion joints and provide insulation. A- nuclei, B- fat globules

Regular dense connective- strong fibers bind body parts together. Found in ligaments and tendons. Poor blood supply so slow healing. A- fibroblasts. B- collagen and elastin

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. A- chondrocytes, B- Matrix (fine collagen fibers), C- Lacunae

Fibrocartilage- tough tissue containing collagenous fibers. Shock absorbers between vertebrae and pubic girdle. A- Chondrocyte, B- Collagen fibers

Elastic cartilage- flexible cartilage make up ears and larynx. Used for flexible support. A- chondrocytes, B- elastin, C- Lacunae

Blood – platelets, found in plasma. Used for blood clotting

Blood – red cells & white cellRed- used for transport, white- immunity

Elastic connective- allows for stretching, found in attachments between vertebrae. A- elastic fibers

Reticular connective- walls of liver and spleen. Used for support.

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

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

Muscle & Nerve Tissue

Muscle Tissue

3 types: Skeletal- Attached to bone and

controlled by conscious effort (Voluntary). Used for movement Striated Long and thin with multiple nuclei

Muscle Tissue Cont.

Smooth- lacks striations found in skeletal, used for involuntary movements Ex- move food through digestive tract

Cardiac- striated muscle found only in the heart At intercellular junction contain

intercalated discs. Allows for heart to contract as one unit

3 Types of Muscle Tissue

Smooth muscle- B- nucleus

Skeletal muscle- A- striations, B- nucleus

Cardiac muscle- A- Intercalated discs, B- cell

Nervous Tissue

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

• Cells called neurons– Responsible for transmitting nervous impulses

to muscles and glands.• Also include neuroglia cells (support cells)

– Support the function of the neurons

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