Lecture #6: Histology

BIOL1410

What is the study of tissues?

Histology

What are the 4 major tissue types?

1. Epithelial Tissue

2. Connective Tissue

3. Muscle Tissue

4. Nervous Tissue

What are the 3 types of membrane junctions?

1. Tight Junctions

2. Desmosomes

3. Gap Junctions

Which junction are protein molecules that are fused together in the cell membrane?

Tight Juncitons

What is the purpose of tight juncitons?

To prevent substances from passing between cells.

What type of connection do desmosomes have?

Loosely attached.

What junction uses linker proteins to join adjacent cells?

Desmosomes

Gap junctions are protein ________ that _______ adjacent cells.

“channels”, “connect”

TRUE/FALSE: Gap junctions allow direct communication between cells.

TRUE: They allow substances to pass form the inside of one cell to the next.

What junctions are extremely important in smooth and cardiac muscle cells?

Gap Junctions

Where is epithelial tissue found?

On all of the body’s surfaces + lines all of the body cavities.

Epithelial tissue is “_________” tissue, meaning that they ____ blood vessels.

“avascular”, “lack”

Cells that form epithelial tissue have what and sit on top of what?

They have one free membrane and sit on top of a basement membrane.

_____ junctions hold together epithelial tissue.

“Tight”

Epithelial tissue reproduce via _______ division.

“mitotic”

Glands located in epithelial tissue are formed from?

Glandular Epithelium.

What are the 2 things that epithelial tissue is classified by?

• # of Cell Layers

• Shape of Cell

What are the types of cells based on # of cell layers?

• Simple Epithelium

  • 1 Layer on basement membrane.

• Stratified Epithelium

  • 2+ Layers with a free surface.

• Pseudostratified Epithelium

  • 1 Layer on basement membrane that looks like multiple.

What are the cell shapes of epithelial tissue?

• Cuboidal

  • Cube/Circular

• Columnar

  • Column/Long Rectangle

• Squamous

  • Irregular + Flattened

• Transitional

  • Cube/Circular → Irregular + Flattened

What are cuboidal cells and columnar cells specialized for?

Secretion + Absorption

Where are squamous cells found?

On the outer surfaces of the skin.

What are squamous cells specialized for?

Resist abrasion.

What are glandular subtype specialized for?

For Secretion.W

What are the 2 types of glands?

Exocrine + Endocrine

TRUE/FALSE: Exocrine glands are ductless.

FALSE: They use ducts as passage ways for secretions.

Where do exocrine glands secrete its products?

Onto a surface or into a cavity.

Single-celled exocrine gland example.

Goblet Cell

• Secretes mucous into a cavity.

• In digestive, urinary, reproductive, and respiratory tracts.

Multi-Cellular Exocrine Gland Examples

• Sudoriferous Glands

  • Produces Sweat

• Sebaceous Glands

  • Produces Sebum (oil)

• Salivary Glands

  • Produces Saliva

TRUE/FALSE: Endocrine glands are ductless.

TRUE: Hormones are released directly into the blood.

________ are the secretions of endocrine glands.

“Hormones”

What is the functions of epithelial tissue?

• Protection

  • Stratified Squamous Epithelium

• Secretion

  • Glandular Epithelium

• Control of Permeability

  • Simple Epithelium

What tissue has cells that are separated from one another by a matrix?

Connective Tissue (CT)

What are the 3 types of cells in CT?

• Blasts

  • Builds matrix.

• Cytes

  • Maintains matrix.

• Clasts

  • Breakdown matrix.

TRUE/FALSE: The matrix is intracellular.

FALSE: It is extracellular and surrounds the cells of the CT.

The ______ provides CT with its characterisitcs.

“matrix”

What are the 3 primary components of the matrix?

1. Protein Fibers

2. Grounds Substances

3. Water

What protein fibers are in the matrix?

• Collagen = Strength

• Elastin = Stretch + Recoil

What are the 3 primary characters of CT?

1. Highly Vascular (with some exception).

2. Lots of Extracellular Matrix.

3. Support + Connect Tissues.

What are the types of CT?

• CT Proper

  • Loose CT

    • Areolar CT

    • Adipose CT

  • Dense CT

    • Dense Regular

    • Dense Irregular

• Cartilage

• Bone

• Blood

What are adipocytes also called?

Fat cells.

How much matrix does adipose CT have?

Very little matrix.

How vascular are adipose CT?

Highly vascular which allows a lot of metabolic activity.

What are the functions of adipose CT?

• Shock Absorption

• Insulation

• Energy Storage

Areolar CT is ___ vascular.

“very”

What fibers are in areolar CT?

Collagen + Elastin

What is the ground substance of areolar CT have?

Hyaluronic Acid

When in areolar CT called lamina propria?

When found in mucous membranes.

What are the cells of the dense regular and irregular CT?

Fibroblasts.

How much ground substance is in dense regular CT?

Very little due to tightly packed bundles of collagen fibers.

TRUE/FALSE: Dense regular CT is poorly vasculature.

TRUE: This is because all of the collagen fibers are tightly packed.

Which direction(s) does dense regular CT run in?

All in the same direction.

Tendons are formed from dense _______ CT.

“regular”

What do tendons do?

Serves to attach muscle → bone.

TRUE/FALSE: Dense irregular CT has lots of matrix.

FALSE: It is also has very little matrix.

What direction(s) does dense irregular CT run in?

More than one direction.

Where is dense irregular CT found?

In areas of the body that gets pulled in more than one direction.

What are cartilage cells called?

Chondrocytes

Where are chondrocytes found in?

Compartments called lacunae.

What type of matrix forms cartilage?

Tightly bound collagen fibers which makes it firm.

What is the ground substance of cartilage?

Chondroitin Sulfate + Hyaluronic Acids

What is the water content of cartilage?

High as up to 80%.

Cartilage is _________, meaning no blood vessels.

“avascular”

Cartilage is both ____ and ________.

“firm”, “flexible”

What 2 forms does bone exist in?

Spongy + Compact

What are bone cells called?

Osteocytes

Osteocytes are found in compartments called _______.

“lacunae”

What is bone matrix made from?

• Densely packed collagen fibers.

• Inorganic calcium + phosphate salts → Hydroxyapetite Crystal

• Water

Are bone vascular?

Yes, bones are highly vascular.

What are the cells of the blood?

Red Blood Cells + White Blood Cells

What is the blood matrix called?

The plasma.

What are the 3 types of muscle?

1. Skeletal Muscle

   • Striated

   • Voluntary Movement

2. Cardiac Muscle

   • Striated

   • Involuntary Movement

3. Smooth Muscle

   • Non-striated

   • In areas that need to stretch.

   • Involuntary Movement

What cells are in nervous tissue?

• Neurons

  • Conduct electrical impulses.

• Glial Cells

  • Surrounds + protects neurons.

TRUE/FALSE: Membranes are organs.

TRUE: They have 2+ tissues which means they are simple organs.

Membranes form __________ multi-cellular sheets.

“continuous”

What are the 3 types of membranes?

1. Mucous Membranes → Mucosa

2. Serous Membranes → Serosa

3. Cutaneous Membranes → Skin

What do mucous membranes line?

Cavities that open to the outside of the body.

What type of epithelial tissue is present in mucous membranes?

Simple Squamous or Pseudostratified

What type of CT is present in mucous membranes?

ALWAYS areolar CT, called lamina proper.

What do serous membranes line?

Cavities that do not open to the outside of the body.

What two membranes form serous membrane?

• Visceral Layer

  • Covers Organ.

• Parietal Layer

  • Against the wall of the thoracic + abdominal cavities.

What are the 3 serous membranes do we talk about?

• Pleura

  • Surrounds the Lung.

• Pericardium

  • Surrounds the Heart.

• Peritoneum

  • Surrounds the abdominal cavity and the viscera.

What is viscera?

Soft internal organs inside body cavities.