Level 4- The Tissue of Level Organization

Tissue

-A group of cells that usually have a common embryonic origin in an embryo and function together to carry out specialized activities

4 basic types of tissue

-Epithelial

-Connective

-Muscular

-Nervous

Epithelial

Cover body surfaces and form glans and line hollow organs, body cavities and ducts

Connective

Protect, support, and bind organs

Is blood a type of connective tissue?

Yes

Is fat a type of connective tissue?

Yes

Muscular

Generate the physical force needed to make body strctures move. They also generate heat used by the body

Nervous

Detects changes in the body and repspond by generating nerve impulses

Cell junctions

- Gap junction

- Basement membrane

- Hemidemosome

- Desmosome

- Adherens junction

- Tight junctions

Tight Junctions

Leak-proof seal between cells

Tight junctions examples

Stomach, Intestines, and bladder

Adherens Junctions

Make and adhesion belt that keeps tissues from separating as they stretch and contract

Cadherin

A transmembrane glycoprotein that forms the belt-like "plaque" (attached to microfilaments to the cytoskeleton)

Desmosomes

act as "spot welds". They also use cadherin glycoprotein.

Very similar to adherens, however the plaque attaches to intermediate filaments oppsed to microfilaments

where do desmosomes occur?

Cardiac muscle and skin

Hemidesmosomes

Half-welds that join cells to the basement membrane

-look like a half desmosome

Gap junction

Pores (connexons) that allow small substances like ions to pass between cells

Epithelial vs Connective. Which as a more dense cell population?

Epitelial

Epithelial vs Connective. Which is Avascular?

Epithelial

Avascular

Not having blood vessels

Epithelial vs Connective. Which usually forms a surface layer with connective tissue underlying and immediately adacent?

Epithelial

Why does epithelial tissue usually form a surface layer with connective tissue underlying and immediately adjacent?

It has a supply of blood vessels, to get nutrients, wastes and oxygen

Epithelial vs Connective. Which has a right rate of cell division?

Epithelial

Why does epithelial tissue have a high rate of cell divison?

If it is a surface layer, epithelial cell have a lot of cell damage from external environmet

General features of epithelial tissue

-Cells are arranged in sheets and are densely packed

-Many cell junctions are present

-Epithelial cells attach to a basement membrane

-Epithelial tissue is avascular but does have a nerve supply

-Mitosis occurs frequently

3 major functions of Epithelium

1. Selective barriers that limit or assist in the transfer of substances

2. Line surfaces and form protective barriers

3. Secreting things like mucous, hormones, and other substances

Apical surface

faces the body surface, cavity , lumen, or duct

Lateral surface

face adjacent cells

Basal surface

Adhere (hemidesmosomes) to the basement membrane (contains basal and reticular lamina)

How are epithelia named?

according to the shape of their cells, and the thickness or arrangement of their layers (of cells)

Squamous

Flat, wide "paving stone" cells- rapid movement between cells

Cuboidal

Cells as tall as they are wide

-Help of absorption, protection, bronical tubules, bladder

Columnar

Cells taller than they are wide

-Ears, eyes, severtion, absorption

Simple

One layer. All cells in contact with basement membrane

-Last line of defence from the outside

Pseudostratified

Appears to have layers, but in reality all cells go from the apex to the base

Stratified

Two or more layers. Only basal layer in contact with basement membrane- that layer gets blood flow. the rest of the layer dont get direct blood flow

Glandular Epithelium

A gland in a single cell or a mass epithelial cells adapted for secretion

Connective tissue

Most abundant and widely distributed tissue in the body

Connective tissue perform these functions

-Bind tissues together

-Support and strengthen tissue

-Protect and insulate internal organs

-Compartmentalize (muscles) and transport (blood)

-Energy reserves (fat) and immune responses

All connective tissues share two basic elements

Sparse cells

Extracellular matrix

Extracellular matrix

Non-cellular material located between and around cells

-Consists of protein fibers and ground substance(fluid, semifluid, gelatinous, or calcified)

Epithelial vs Connective

Which has free surfaces?

Epithelial

Collagen

The main protein of connective tissue and the most abundant protein in the body, making up about 25% of total protein content

Fibroblasts

Large flat cells that move through connective tissues and secrete fibers and ground substances

-The most numerous cell of connective tissue. They secrete protein fibers and a ground substance

Collagen fibers

Strong, Flexible bundles of the protein collagen, the most abundant protein in you body

Mast cells

Abundant along blood vessels. They produce histamine, which dialates small blood vessels during inflammation and kills bacteria

Plasma cells

Develop from B lymphocytes. They secret antibodies that attack and neatralize foreign substances

Ground substance

The material between cells and fibers. It is made of water and organic molecules. If supports cells and fibers, binds them together, and provides a medium for exchanging substances between blood and cells

Neutrophils

White blood cells that migrate to sites of infection that destroy microbes phagocytosis

Eosinophils

White blood cells that migrate to sites of parastic infection and allergic responses

Adipocytes

Fat cells that store fats. They are found below the skins and around organs

Elastic fibers

Stretchable but strong fibers made of proteins, elastin, and fibrillin. They are found in skin, blood vessels, and lung tissue

Macrophages

Develop from monocytes and destroy bacteria and cell debris by phagocytosis

Reticular fibers

Made of collagen and glycoproteins. They provide support in blood vessel walls and form branching networks around various cells

..."Blast"

Immature cell

..."Cyte"

Mature cell

Chondroblast

give rise to cartilage

Osteoblast

give rise to bones

Connective tissue cells secrete 3 common fibers

Collagen fibers

Elastin fibers

Reticular fibers

Embryonic connective tissue

-Mesenchyme

-Mucous connective tissue

Mature connective tissue

1. Loose connective tissue

2. Dense connective tissue

3. Cartilage

4. Bone

5. Blood

1. Loose connective tissues

Areolar connective tissue

The most widely distributed in the body. It contains several types of cells and all three fiber types

-Used to attach skin and underlying tissues, and as a packing between glands, muscles and nerves

1. Loose connective tissue

Adipose tissue

Located in the subcutaneous layer deep to the skin and around organs and joints.

-Reduces heat loss and serve as padding and as an energy source

1. Loose connective tissue

Reticular connective tissue

A network of interlacing reticular fibers and cells

-it forms a stroma (scaffolding) used by cells of lymphoid tissues as the spleen and lymph nodes

2. Dense Connective Tissue

Consists predominantly of fibroblasts and collagen fibers randomly arranged in sheets

-Provides strength when forces are pulling from many different directions

2. Dense connective tissue

Dense regular connective tissue

Comprise tendons, ligaments, and other strong attachments where the needs for strength along one axis is mandatory

2. Dense connective tissue

Elastic connective tissue

Consists predominantly of fibroblasts and freely branching elastic fibers

-It allows stretching of certain tissues

Cartilage

A tissue with poor blood supply that grows slowly. When injured or inflamed, repair is slow

3. Cartilage

Hyaline cartilage

The most abundant type of cartilage; it covers the end of long bones and parts of the ribs, nose, trachea, bronchi, and larynx.

-It provides a smooth surface for joint movement

3. Cartilage

Fibrocartilage

Its thick bundles of collagen fibers, is a very strong, tough cartilage

FIbrocartilage discs

The intervertebral spaces and the knee joints support the huge loads up and down the long axis of the body

3. Cartilage

Elastic cartilage

Consists of chondrocytes located in a threadlike network of elastic fibers

-It makes up the malleable part of the external ear and the epiglottis

Interstitial growth

-Growth from within the tissue

-Chondrocytes rapidly divide and form matrix

-Childhood and adolescence

Appositional growth

-Growth at the outer surface of the tissue

- cells on the inner layer of perichondrium differentiate into chondroblasts and create extracellular matrix causing matrix to be deposited on the outer surface of cartilage and a growth in width

- starts later and continues through adolescence

Bone

A connective tissue with a calcified intracellular matrix. Bones work with skeletal muscles to provide movement, and protection, they store triglycerides, red bone marrow, and calcium

Blood and lymph

Atypical liquid connective tissues

Location of Dense fibruos connective tissue

Tendons, ligaments, and attachments between organs and dermis of the skin

Location of Reticular connective tissue

Liver, lymph nodes, spleen, and bone marrow

Location of Elastic connective tissue

Lung tissue and arteries

Location of loose connective tissue

Packing between glands, muscles, and nerves; attachments between skin and underlying tissue

Location of Hyaline cartilage

End of long bones, joints, respiratory tubes, costal cartilage of ribs, nasal cartilage, and embryonic skeleton

Location of elastic cartilage

Auditory tube, external ear, epiglottis

Location of fibrocartilage

Connection between pubic bones, intervertebral disks

Electrical excitability

The ability to respond to certain stimuli by producing electrical signal

-action potentials

Epithelial membranes

epithelium+connective tissue

Mucous membranes

Line interior body surfaces open to the outside

-digestive tract

-Respiratory tract

-Reproductive tract

Serous membranes

Line some internal surfaces

-Parietal layer next to body wall

-Serous fluid between layers

-Visceral layer next to organ

Cutaneous membrane

Skin

Endocrine glands

Glands that secrete their own contents directly into the interstitial fluid which then diffused directly into blood

Exocrine glands

Glands that secrete their own contents into a lumen or duct

Parenchymal

Cells of an organ consist of that tissue which conducts the specific function of the organ

Stroma

Connective tissue, blood vessels, nerves