Class 9/6: Cells and Tissues

Identify the four basic types of Tissues Define and identify epithelial tissues based on layers and cell type Define and identify connective tissue proper based on the cell type and components of the ECM Identify the five membranes of the body Identify and differentiate between superficial and deep fascia

Identify the 4 basic types of tissues

Identify the 4 basic types of tissues

• epithelial tissue

• connective tissue

• muscle tissue

• nervous tissue

What is each tissue composed of?

• Cells

• Extracellular matrix

what is the function of the connective tissue?

connects and supports structures

function of muscle tissue.

produces movement

function of nervous tissue

for control and sending messages

function of epithelial tissue

think lining of a surface

What does the ratio of cells:Ecm depend on?

depends on function

Two types of epithelial tissue

membranous and glandular

Structure of epithelial tissue

many cell + little extracellular matrix

Membranous epithelial tissue

cover the outer and inner surfaces of body organs and cavities

Where would you find epithelial tissues in the body?

• line body surfaces

• line inside and outside of hollow organs

• line body cavities and the outside of hollow organs

Characteristics of exocrine glands

• have ducts, secrete locally onto surfaces or in cavities

  • unicellular or multicellular

goblet cell

only unicellular exocrine gland

• produces mucin that turns in to mucus when mixed with water

• wedged in between the epitheileal

exocrine glands characteristics

• multicellular

• continuation of epithelial sheet that invaginates into connective tissue

  • ex: sweat glands, mammary glands, salivary glands

Characteristics of Epithelia:

• Cells are held together by tight junctions

• Avascular (no blood supply) but innervated

• Nutrients reach epithelia from capillaries in underlying connective tissue

• Supported by a Connective tissue via the basement membrane

What is the purpose of an intercellular junction?

provide a physical connection between the adjacent cells or between a cell and the extracellular matrix in plants and animals.

What is the difference between the apical and basal surface?

The apical surface faces the lumen (inside of a hollow organ) while the basal or basolateral surface is adjacent to the underlying tissue.

What is the difference between simple, pseudostratified and stratified epithelium?

• simple: one layer of cells

• stratified: more than one layer of cells

• pseudostratified: appear to be more than one

  • all pseudo will have goblet cells and cilia

  • nucleus, not all in a row

describe squamous cells

• flat, plate-like

• wider than tall

• oval nuclei that bulges into the lumen

describe cuboidal cells

as wide as they are tall, circular nuclei

describe columnar

taller than they are wide, oval nuclei

Transitional Epithelium

Special ability to stretch and change shape, UMBRELLA CELLS

Cells transition between cuboidal when relaxed and squamous when stretched

function of the transitional epithelium

Allow stretch in the structures of the urinary tract

where is the transitional epithelium exclusively found

urinary tract

What features identify the apical cells of transitional epithelium?

Nucleus is always round

Identify two types of cell specializations

Goblet cells and Cilia

Goblet cells

produce mucus • Lubricates apical surfaces • Protection

cilia

Move mucus across apical surface

What features identify a simple cuboidal epithelium?

Simple:

• One layer of cells is present

Cuboidal:

• Apical surface cells are cube shaped in cross section

• As wide as they are tall

• Round nuclei

What features identify a simple columnar epithelium?

Simple:

• One layer of cells is present

Columnar:

• Apical cells are column shaped in cross section

• Cells are taller than they are wide

• Oval nuclei, located near the basal surface

• Cells may display apical cilia and/or goblet cells

Function of Simple Cuboidal and Columnar Epithelium

Absorption and secretion

What features identify a pseudostratified columnar epithelium?

Pseudostratified:

• All cells touch the basement membrane, but not

all cells reach the apical surface

• All cells have cilia and goblet cells; AKA

respiratory epithelium

Columnar:

• Apical cells are column shaped in cross section

• Cells are taller than they are wide

• Oval nuclei, located near the basal surface

Function of the pseudo stratified columnar epithelium

protection

Where can Pseudostratified Columnar Epithelium be found in the body?

respiratory tract

Which tissue is the most abundant and diverse?

connective tissue

function of connective tissue

• Anchors muscles for movement

• Carries/stores nutrients

• Insulation

• Immunity

Fibroblasts

• Spindle or star shaped

• Found in connective tissue proper

Adipocytes

• Fat cells which store lipid in cytoplasm

• Provide cushion, insulation and thermoregulation

Blood cells

Defend against infection by launching an immune response when antigens are present

Chondrocytes

• Found in cartilage

• Reside in spaces called lacunae

Osteocytes

• Found in bone

• Reside in spaces called lacunae

Macrophages

Immune cells

Name the cells that are found in connective tissues.

• Fibroblasts

• Adipocytes

• Blood cells

• Chondrocytes

• Osteocytes

• Macrophages

What type is collagen?

• Type I (bone, skin, tendons, ligaments)

• Type II (hyaline cartilage)

What type is reticular

• Type III collagen

function of collagen

Provide tensile strength

function of reticular

Support tissue structure

function of elastic fibers

• Allow stretch and recoil

• Stain black (verhoeffs)

Name three types of fibers that may be found in connective tissues

• collagen

• reticular

• elastic fibers

Ground Substance

Complex gel secreted by fibers that is made of huge, water attracting macromolecules that produces a flexible medium through diffusion of nutrients and waste can occur.

What is the function of the ground substance?

Because it is so flexible it can also resist compression.

4 types of connective tissue

1. Connective tissue proper

2. Cartilage

3. Bone

4. Blood

Loose Areolar Connective Tissue

• Underlies epithelia, surrounds muscle, nerves and blood vessels

• Retains bodily fluid

Loose Areolar Connective Tissue Cells and fibers which may be present:

• Fibroblasts

• Blood cells

• Adipocytes

• Collagen and elastic fibers

Reticular Connective Tissue

cells and fibers which may be present:

• Fibroblasts

• Reticular fibers (type III collagen)

Reticular Connective Tissue

Forms a network that creates a support for adipose, lymph nodes, bone marrow, kidney, liver, etc

Adipose Connective Tissue “Fat” Cells and fibers which may be present:

• Lobulated fat cells arranged in a cluster

• Maintains shape, cushions and provides insulation

Adipose Connective Tissue “Fat”

• Adipocytes

• Reticular fibers (type III collagen)

Dense Connective Tissues Contain the following cells and fibers:

• Fibroblasts

• Mostly collagen I (elastic or a combination)

What are the similarities and differences between dense regular and irregular connective tissue?

Dense Regular Connective Tissue

• Fibers are arranged in parallel

• Location: Uni-directional strength, e.g. ligaments and tendons

Dense Irregular Connective Tissue

• Fibers are arranged randomly

• Location: Multi-directional strength, e.g. dermis of the skin

Membranes are formed by which two structures.

Epithelium + Connective Tissue

All epithelium must maintain a connective tissue. Why?

If not, they won’t be able to receive support or nutrients

Identify the epithelium and connective tissue of the skin

Epithelium (Epidermis)

• Stratified Squamous

Connective Tissue (Dermis)

• Dense irregular connective tissue

Cutaneous Membrane (Skin):

True epithelium; exposed to an external environment

Mucus Membrane

• Produce mucus

• Are true epithelia

• Have goblet cells

• Cilia always present

Identify the epithelium and connective tissue of a mucus membrane.

Epithelium

• Simple Columnar OR

• Pseudostratified columnar

Connective Tissue

• Loose connective tissue

• “Lamina Propria” specific to mucus producing membranes

identify the mucus membrane

Pseudostratified Columnar

identify the mucus membrane

Simple Columnar

Identify the epithelium and connective tissue of a serous membrane

Epithelium

• Simple squamous

Connective Tissue

• Loose connective tissue

Serous membranes (Mesothelium)

• Produce serous fluid within a body cavity

• Lines a body cavity (mesothelium)

Identify the epithelium and connective tissue of an endothelial membrane

Epithelium

• Simple squamous

Connective tissue

• Loose connective tissue

Endothelial Membrane

• Lines blood vessels and the heart

• Release substances that affect the vessels and the heart

Fascia

Mixed layer of connective tissues

Superficial fascia:

Loose Areolar Connective Tissue

Adipose Connective Tissue

Deep fascia

Dense Regular Connective Tissue Dense Irregular Connective Tissue

blood

• Distributes nutrients, oxygen and protection

• The ground substance of blood is less viscous

White blood cells (Leukocytes)

• have distinctive nuclei and cell size

• Function in immunity

Red blood cells (Erythrocytes)

• Concave and are anucleate

• Function in gas transportation (O2 and CO2)

Platelets

• Cell fragments, anucleate

• Function in blood clotting