Biology Lecture 3: Epithelial Tissues

Questions and Answers

What is the main function of epithelial cells?

To facilitate the exchange and transportation of ions and molecules

What type of epithelial tissue is responsible for protection?

Non-ciliated epithelium

What is the primary function of connective tissue cells?

To provide structural support and connect the body's structures

What is the characteristic of epithelial cells that allows them to perform their functions?

Their ability to form layers of varying sizes and shapes Signup and view all the answers

What is the name of the type of epithelial tissue that helps in moving substances along the surface?

Ciliated epithelium Signup and view all the answers

Where are epithelial cells typically located in the body?

At the surfaces that cover the body and individual organs Signup and view all the answers

What is the primary component of the extracellular matrix (ECM)?

Proteins Signup and view all the answers

What is the main function of the extracellular matrix in providing a scaffold for cellular attachments?

To provide a framework for cellular growth Signup and view all the answers

What type of tissue is adipose tissue classified as?

Connective tissue Signup and view all the answers

What is the term for the rope-like fibers found in the extracellular matrix?

Collagen fibers Signup and view all the answers

What is the term for the loose, irregular connective tissue found in the skin?

Dermis Signup and view all the answers

What is the primary function of the extracellular matrix in transmitting information to cells?

To transmit chemical messengers Signup and view all the answers

What type of tissue is cartilage classified as?

Connective tissue Signup and view all the answers

What is the term for the skin as a whole, including the epidermis, dermis, and hypodermis?

Skin organ Signup and view all the answers

What is the main function of macrophages in connective tissue?

To engulf and digest invaders Signup and view all the answers

What is the main component of elastic fibers?

Elastin Signup and view all the answers

What is the role of lysyl oxidase in collagen synthesis?

To cross-link collagen fibers Signup and view all the answers

What is the main function of fibroblasts in connective tissue?

To synthesize collagen fibers Signup and view all the answers

What is the main component of proteoglycans?

Glycosaminoglycans Signup and view all the answers

What is the main function of ground substance in connective tissue?

To support the framework of the tissue Signup and view all the answers

What is the term for the condition characterized by faulty synthesis of fibrillin?

Marfan's syndrome Signup and view all the answers

What is the hierarchical structure of collagen?

Tropocollagen -> collagen fibers Signup and view all the answers

What percentage of dry mass of cartilage is composed of collagen II fibrils and fibres?

60% Signup and view all the answers

What type of cartilage is found on most joint surfaces?

Hyaline cartilage Signup and view all the answers

What is the function of tendons and ligaments?

To connect muscles to bone and bones to bones Signup and view all the answers

What is the hierarchical organization of collagen in tendons and ligaments?

Hierarchical organization of collagen into larger and larger fiber bundles Signup and view all the answers

What is the result of crimped collagen in tendons and ligaments?

Provides physical separation in case of damage Signup and view all the answers

How do tendons and ligaments respond to mechanical stimulus?

By upregulating collagen gene expression Signup and view all the answers

What is the effect of exercise on collagen production in tendons and ligaments?

Increases collagen production Signup and view all the answers

How are the mechanical properties of tissues determined?

By applying a force to the tissue and measuring how much it deforms Signup and view all the answers

What is the unit of measurement for stress?

N/m2 Signup and view all the answers

What is the modulus of a material?

Stress divided by strain Signup and view all the answers

What is the mechanical property of a material that is described as its ability to withstand compression?

Stiffness Signup and view all the answers

What is the role of lysyl oxidase (LOX) in collagen?

It crosslinks collagen Signup and view all the answers

What is the mechanical property of a material that is described as the force at which it breaks?

Absolute strength Signup and view all the answers

What is the characteristic of tendons that allows them to store and return elastic strain energy?

Extensibility Signup and view all the answers

What is the composition of cartilage that makes it strong in compression?

Dense network of very fine collagen II fibrils Signup and view all the answers

What is the mechanical property of a material that is described as the force at which it permanently deforms?

Yield strength Signup and view all the answers

What is the characteristic of collagen that makes it strong in tension?

Its ability to crosslink with other collagen fibers Signup and view all the answers

Study Notes

Epithelial Cells & Tissues

Located at the surfaces of the body and individual organs, and line inner surfaces of tubular and hollow structures
Function: specialized for selective secretion and absorption of ions and organic molecules, and for protection
Types of epithelium:
- Based on cell organization (structure)
- Based on tissue function: exchange, transportation, ciliated, secretory, and protection

Connective Tissue Cells

Function: specialized to connect, anchor, and support the structures of the body
Types: areolar, bone, skin, adipose, cartilage, tendons, and ligaments

Connective Tissue Components

Extracellular matrix (ECM) consists of proteins, polysaccharides, and minerals
Proteins: collagen, elastin, and proteoglycans
Glycosaminoglycans: large polysaccharides
Proteins: glycoproteins, protein core, and oxygen/nitrogen

General Connective Tissue Cells

Macrophages: engulf and digest invaders
Fibroblasts: produce and secrete collagen, part of connective matrix

Protein Fibers

Collagen: hierarchical structure, strong and stiff, provides scaffold for cellular attachments
Elastic fibers: elastin, cross-linked, provides elasticity

Connective Tissue Types

Blood: specialized connective tissue
Areolar: loose connective tissue
Bone: rigid connective tissue
Skin: organ composed of epithelial, connective, muscle, and nervous tissues
Adipose: loose connective tissue with adipocytes
Cartilage: avascular, dense network of collagen II fibrils and fibers
Tendons & ligaments: dense regular connective tissue

Cartilage

Types: hyaline, fibrocartilage, and elastic cartilage
Hyaline cartilage: found on most joint surfaces, high tension, no blood supply, surrounded by perichondrium
Fibrocartilage: more collagen, firm but flexible
Elastic cartilage: more elastic fibers, firm but flexible

Tendons & Ligaments

Connect muscle to bone (tendons) and bones to bones (ligaments)
Composed of fibroblasts, hierarchical organization of collagen into larger fiber bundles
Collagen is crimped, providing physical separation in case of damage

CT (Tendon) Remodeling

Responds to mechanical stimulus
Fibroblasts respond to chemical stimuli, such as growth factors
Upregulates collagen gene expression, producing and secreting collagen

Mechanical Properties of CT

Mechanical properties can be determined by applying force and measuring deformation
Stress: force per unit area
Strain: change in length or extension
Modulus: stress/strain
Yield strength: force at which it permanently deforms
Absolute strength: force at which it breaks

Collagen Mechanical Properties

Tropocollagen: very strong, quite stiff, good in tension
Lysyl oxidase (LOX) crosslinks: strong and stiff

Cartilage Mechanical Properties

Good in compression, resistant to compression and shear
Dense network of collagen II fibrils and fibers
Collagen orientation reflects resistance to compression or shear

Tendons Mechanics

Extensible, storing and returning elastic strain energy
High modulus of elasticity (young's modulus)

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Description

This quiz covers the structure, function, and types of epithelial cells and tissues, including their role in secretion, absorption, and protection.