CTR connective tissue

what are the six functions of connective tissue?

1. insulating (eg. fat)
2. storage of reserve fluids and energy
3. movement
4. support
5. protection (3-5, bones, cartilage etc)
6. transport (eg. blood)

what 3 factors do all connective tissue have in common that differentiates them from other tissue types?

1. share a common origin, all arise from the mesenchyme


1. mesenchyme = loose and fluid embryonic tissue which can be manipulated (like clay) and move easily (unlike other tissue types such as epithelial tissue which is formed in sheets)
2. have different degrees of blood flow (vascularity)


1. eg. cartilage = avascular, bones = vascular
3. all connective tissue is made up of nonliving material known as the extracellular matrix


1. the actual cells float/are found within this matrix

what is the extracellular matrix composed of? (2)

1. ground substance


1. a watery, rubbery unstructured material that fills spaces btw cells + protects cells
2. made up of starch + protein molecules mixed with water
3. flexible
4. is anchored by proteoglycans, proteins that are connected to a bunch of starchy molecules called glycosaminoglycans (GAGs)
2. FIBERS


1. function: provides support and structure to the ground substance
2. collagen, elastic, reticular

collagen fibers: features + functions

features: strongest + most abundant fiber

* is tough and flexible

function: can withstand tensile forces

elastic fibers: features + functions

long + thin

form branching framework in matrix

made up of the elastin protein, allows it to stretch and recoil (like rubber bands)

found in skin, lungs and blood vessel walls

reticular fibers: features + functions

short finer collagen fibers with an extra coating of glycoprotein

connect together to form networks that cradle/support organs

connective cell phases

immature: suffix -blast

* function: secretes ground substance + fibers to form extracellular matrix

mature: suffix -cyte

* less active
* maintain health of matrix built by the blast cells
* can revert back to blast state to repair/generate matrix

connective tissue proper subtypes (6)

1. loose = more ground substance > fibres


1. areolar
2. reticular
3. *adipose*
2. dense = more fibres > ground substance


1. regular
2. irregular
3. elastic

areolar tissue

1. a delicate network throughout body with lots of flexible ground substance


1. all 3 types of fibers present (collagen, reticular, elastic)
2. *mostly fibroblasts with* transient cells that monitor tissue for pathogens + damaged cells


1. transient cells incl eg. macrophages
3. *most common connective tissue*
4. function: links skin to muscle and organs + allows passage of nerve & blood vessels
5. *found directly beneath epidermis of skin*

adipose tissue

1. primarily composed of adipocytes with large lipid vacuoles (the vacuole squishes the nucleus to side of cell)
2. provides storage for fuel/*nutrients* and energy, physical protection, insulation
3. *found under skin (subcutaneous fat), between internal organs (visceral fat) and in inner cavities of bone (bone marrow adipose tissue)*

reticular tissue

networks of reticular fibres cradle/support organs/tissue

* supporting framework for lymph nodes, spleen, tonsils, bone marrow + liver

dense regular

bundles of collagen fibres organized neatly in parallel rows with flattened nuclei in between

* supports/protects/holds bones, muscles and other tissue in place
* *makes up ligaments, tendons, inner layer of skin and the sclera (white outer layer of the eye)*
* *resists unidirectional tensile stress*

dense irregular

1. bundles of collagen and elastic fibres arranged in disorderly fashion/all different directions


1. absorbs tension in all directions → good for areas that need full range of motion eg. joint capsule of shoulder
2. more rounded nuclei
3. makes up the dermis

elastic dense connective tissue

* mostly made of elastic fibres
* varies on how sparsely/tightly arranged it is
* *allows for stretching and recoiling to original configuration*
* *found in walls of large arteries and bronchial tubes, ligaments associated with the vertebral columns*

features of cartilage tissue

* avascular but have bloodstream go close to cartilage for diffusion of substances

elastic cartilage

* has elastic fibers in matrix
* maintains structure while allowing great flexibility
* makes up external ear + epiglottis

hyaline cartilage

* makes up the costal cartilage of the ribs, trachea, larynx, articular cartilage of joints, nose
* function: supports/cushions; resists compressive stress
* has collagen fibers in matrix but not visible; matrix appears glassy under microscope

Fibrocartilage

* makes up discs in between each vertebrae (intervertebral discs), pubic symphysis and discs of knee joints
* composed of many thick collagen fibers
* less firm than hyaline cartilage matrix
* function: tensile strength allows it to absorb compressive shock

functions of bones (5)

* movement: joints
* structure
* protection: of internal organs
* hemopoiesis
* production of blood cells
* mineral storage: calcium esp

periosteum

*irregular connective tissue* layer that covers outside of bone

* *holds in place blood vessels and nerves that vascularize the osseous tissue*

compact bone

* made up of osteons, well vascularized
* has osteocytes maintaining calcified matrix in lacunae (spaces between osteons)
* very dense

spongy bone

* made up of projections called trabeculae
* bone marrow fills spaces between trabeculae
* trabeculae are covered by the endosteum

osteon

* structural unit of compact bone
* made up of lamellae, rings of collagen fibers that run in alternating directions
* function: disperse twisting forces when moving
* *in the centre of the osteon is the central canal aka. the Haversian canal where the blood vessels and nerves are found*
* has blood vessels and nerves throughout

lacunae

* spaces between the lamellae where osteocytes are situated

medullary cavity

hollow cavity within shaft of long bones (diaphysis) where bone marrow is stored (yellow bone marrow, lipid rich in adults, red bone marrow in children)

surrounded by a thin layer of spongy bone and a layer of compact bone

what is the extracellular matrix in blood? what is the ground substance? cells?

the soluble fibres in the plasma (ground substance) = fluid matrix

cells: erythrocytes and leukocytes

rbc vs other cells?

mature rbc has no nucleus or organelles, instead has 250 million molecules of hemoglobin

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note: easy to mix up pics of blood and adipose tissue

* big coloured dots, the same size as the other cells = wbc
* big blobs with darkened blobs as nuclei = adipose