Lecture 2 Connective Tissue, fibers, pathways

What are the four types of connective tissue?

Connective Tissue Proper (fat/fibrous)

Skeletal (bone)

Cartilage

Blood

Components of connective tissue.

Cells

Matrix

Ground Substance

Characteristics of Connective Tissue

Small number of cells

Large amount of Matrix

Ground substance

Originates from mesenchymes

Connective Tissue cells contain

Fibroblast (Fibrous tissue)

Chondroblast (Cartilage)

Osteoblast (Bone)

Fat (Adipose)

WBC (White blood cells)

Macrophage (kills stuff and worker)

Mast Cell (contains chemicals which trigger inflammation and allergic responses against Pathogens)

Connective Tissue Matrix is made out of three fibers…

Collagen

Elestin

Reticular

Difference between fibers and cartilage

(in minecraft terms)

Cartilage is like a a wood house

Fiber is like a wooden plank

Cartilage is it’s own structure

While fiber is just a building material for something else in this case (matrix)

Collagen Fiber Function

Structural support (holds stuff together and in place)

Tensile Strength (resist stretch)

Connective Tissue Component (main tissue)

Bone Health (main structural framework, giving it strength and withstanding stress)

Skin elasticity (collagen helps maintain firm skin, look younger)

Regeneration (tissue repair, scar formation boo… attracts cells needed for healing and provides scaffold for new tissue growth)

Major component for many things

Joint health

Organ support

Immune system support (amino acids in collagen are essential for immune system) (Also blocks stuff)

Collagen fibers location!

• Bone: Provides scaffolding and durability. 

• Tendons & Ligaments: Arranged in parallel to provide high tensile strength. 

• Skin: Found in the dermis, providing strength and structure. 

• Cartilage: Contributes to the structure of cartilage, such as in the nose and ears. 

• Blood Vessels: Forms a supportive network within arteries and other vessels. 

• Organs: Supports the structure of many internal organs. 

• Cornea: Type I collagen provides strength to the transparent outer layer of the eye. 

What are collagen fibers the building blocks of?

• Tendons & ligaments (strength)

• Dermis of skin (support, durability)

• Cartilage (flexibility + support)

• Bone (strength + framework for minerals)

• Areolar & reticular tissues (soft support)

• Scars & basement membranes (repair + anchoring)

Elestin Fiber function is to

provide elasticity and recoil (useful in lungs too)

support tissue structures

allows organs to withstand blood flow (like blood vessels like arteries)

It’s what allows things to stretch, like doing yoga or smth

Where tf is it found?

Skin dermis

Lungs

Blood Arteries

Ligaments, particular in the spine

Cartilage

Tissue

Reticular fiber function (had no idea what this was for a while)

• Structure: Unlike the thick, straight bundles of collagen fibers, reticular fibers are thin, delicate, and highly branched, forming a net-like pattern.

• basically just structure

Where? 🤔🤔

Stroma of the spleen,

lymph nodes, (kidney bean tissue)

red bone marrow,

liver,

kidneys.

What the hell is the Extracellular Matrix (ECM)?

The ECM is what makes connective tissue connective.

It’s a gel-like substance

It’s a non-living framework that provides mechanical and structural support. It’s non-living because the protein structures, and the ground substance isn’t living, also thus why it is avascular.

Is made out of the three fibers, collagen, elastin (or elastic?), and reticular, which give it its strength, stretch, and cushioning.

It also determines the tissue properties, such as whether it is rigid or soft.

It uses a “ground substance” which fills up the “empty space” often visualized. as a blank space.

It’s found ANYWHERE IN CONNECTIVE TISSUE. bone, blood, cartilage, etc

So what are the three things the ground substance is made of?

It’s made of three things,

proteoglycan (attract water, resist compression, hydrate cells)

glycosaminoglycan (bind water to provide firmness to cells)

glycoprotein (helps cells attach to the ECM)

and the ground substance’s function?

It cushions and supports cells

Fills space

Allows exchange of nutrient and waste diffusion between cells and blood

Regulates cell behavior, growth, migration, and differentiation

Remember the animated videos of blood cells moving through the tubes or veins? the empty space is the ground substance/matrix

First what is connective tissue proper?

One of the main categories of connective tissue, packing, binding, and supporting tissue.

Has Two main types of connective tissue proper, each with 3 different types with 6 in total. (add)

What is Loose CT, one of the two pathways of CT proper?

Soft, Flexible, few fibers with lots of ground substance or space

Like the name itself, loose, not very dense

Analogy: cotton padding

Location: squishy places like bone marrow, organs, fat, eyes, etc

What is Dense CT, the second pathway of CT proper?

Little Ground substance

Strong, tough, like the name, dense

Analogy: Ropes

Location: Tendons, Ligaments, Dermis, joints, organs, arteries

Areolar Loose connective tissue function

Wraps and cushions organs; macrophages (WBC) phagocytize (eat) bacteria

It plays an important role in inflammation and it holds and conveys tissue fluid

Location: Epithelia (any tissue that lines the or covers surfaces of the body) packages organs,

Forms lamina propria (thin layer of connective tissue) of mucous membranes

Adipose CT Loose function and location

Located in the skin of the hypodermis, around kidneys and eyeballs, within abdomen, in breasts

Provides reserve food fuel, and insulates against heat loss; supports and protects organs

Essentially the fat storages (long term)

Reticular Connective Tissue proper (F&L)

Forms a soft internal skeleton (stroma) (The cells and tissues that support and give structure to organs, glands, or other tissues in the body. The stroma is mostly made up of connective tissue, blood vessels, lymphatic vessels, and nerves)

that supports other cell types including white blood cells (attacks), mast cells (applies debuffs, inflammatory), and macrophages (engulfs bacteria, erase traces, helps tissue repair)

Dense irregular CT (F&L)

Withstands tension exerted in MANY DIRECTIONS; provides structural strength

Is the reason why your hand skin can stretch in any direction fine

Fibrous capsules of organs and joints

Dermis of skin

Submucosa (thick inner connective layer of digestive)

Dense regular CT (F&L)

Attaches muscles to bones or to muscles

attaches bones to bones

withstands great tensile stretch when pull is applied in ONE DIRECTION

because of this, your arms will break if pulled in the wrong direction

Tendons

most ligaments

aponeuroses

Dense Elastic CT (F&L)

allows recoil for tissue following stretching (twisting bending stretching, throwing)

Maintains pulsatile flow of blood through arteries (blood flows in pulses and waves synced with the heartbeat, not in a wave)

Aids passive recoil of lungs following inspiration (inhalation)

Found in walls of large arteries

certain ligaments associated with the vertebral column (spine)

Within the walls of the bronchial tubes (lungs)