Connective Tissue

Functions mainly to bind and support other tissues

• Areolar Tissue is loose connective tissue that consists of a meshwork of collagen, elastic tissue, and reticular fibres - with many connective tissue cells in between the meshwork of fibres.

• Found in dermis• also found in or around mucous membranes, and

around blood vessels, nerves, and the organs of the body.

Adipose Tissue loose fibrous connective tissue packed with

many cells (called "adipocytes") specialized for storage

of triglycerides more commonly referred to as "fats".

• Adipose tissue forms a thick layer under the skin, around the kidneys and in the buttocks.More generally, it is found at the same locations throughout the body as areolar connective tissue.

• Specific examples of the locations of adipose tissue include:o Subcutaneous layer deep to skino Around the hearto Around the kidneyso Yellow marrow of the long boneso Padding around the jointso Inside the eye-socket, posterior to the eyeball.

• White adipose tissue (WAT) or white fat is one of the two types of adipose tissue found in mammals.

•  brown adipose tissue.o Found in newborns and hibernating animals

• Connective tissues have a sparse population of cells scattered through an extracellular matrix

• Matrix generally consists of a web of fibers. o May be liquid, jellylike or solid

• In most cases, the connective tissue cells secrete the matrix

Connective Tissues• Unlike epithelial tissues, connective tissues have

abundant matrix (intercellular material) and have a good blood supply (expect cartilage)

• Fibroblast is common cell typeo Star shapedo Secretes high amounts of protein

• Leukocytes are a type of white blood cell wonder around connective tissues

• Macrophages function as scavenger cell and defend against infection

macrophage

Leukocytes• Neutrophils

o Most numerous (~60%)o Only occasionally found outside of bloodo Anti-bacterial cells which lyse bacterial cellso Rapidly gather during inflammation

• Eosinophilso 2-4%o Associated with allergies and parasites

• Basophilso >1% o Seems to function similar to mast cells, involved in inflammation

• Monocyteso largest WBC, 5%o Same function as macrophages – engulf and digest

• Lymphocyteso 30%o Commonly found in connective tissueso Respond to inflammation, mediating and regulating immune responses

• Mast Cell located throughout connective tissues adjacent to blood vesselo Help release heparin and histamine

Proteins within the connective tissues

• Three kinds of connective tissue fiberso Collagenous fibers

• Made of collagen protein.• Collagenous fibers are nonelastic and do NOT tear

easilyo Elastic fibers

• Made of protein called elastino Long threads o Elastin fibers provide a rubbery quality

o Reticular fibers• Most thin highly branched• Attached connective tissue to surrounding

tissue

Collagenous fibers

Elastic fibers

Reticular fibers

loose connective, adipose tissue, fibrous

connective tissue, cartilage, bone and

blood

Loose Connective Tissue

• Found throughout body • Binds body parts

together• Such as skin and

underlying organs• Majority are fibroblasts

o separated by gel-like substance

o Containing collagenous and elastic fibers

Loose connective tissue binds epithelia to underlying tissues and functions as

packing materials, holding organs in place

• Fibroblasts – secrete protein ingredients of the extracellular fibers

• Macrophages – WBC that roam the maze of fibers, engulfing bacteria and debris of dead cells

Adipose Tissue• Specialized form of loose connective tissue• Adipose tissue pads and insulates the body• Stores fuel as fat molecules• Each cell swells when fat is stored and shrinks

when the body uses fate as fuel

Fibrous Connective Tissue

• Extremely dense due to large amounts of collagenous fibers

• Organized into parallel bundles to maximize strength

• Tendons• Ligaments

Tendon

Cartilage• Has an abundance of collagenous fibers

embedded in rubbery matrixo Matrix is made of protein-carbohydrate complex

• Chondrocytes secrete collagen• Collagenous fibers make cartilage strong yet

flexible• Skeleton of shark is made of cartilage• Animals are made of embryonic skeletons are

cartilaginous• Flexible supports• Pinna, vertebral disks

Cartilage• Lacks a vascular system

• Heals slowly• Cartilage cells (chondrocytes) lie within

lacunae in the gel like fluid matrix

Hyaline Cartilage• Most common cartilage

• White in color• Abundant fine collagen fibers• Found at the end of the bone• Supports respiratory system

Hyaline cartilage in the trachea

Elastic CartilageStains a little darker

Made with elastic fibersProvides framework for external ears & part of

larynx

FibrocartilageHelps absorb shock

Found in intervertebral disks, knees and pelvis

Tough tissue with many collagenous fibers

Bone• Extremely dense!

• Most rigid connective tissue• Deposits of mineral salts and collagen

within the matrix• Protein and salt ratio is just perfect

• Internal support of bodyProtects

• Forms muscle attachments• Cite for blood cell formation

• Stores fats

• Skeleton is made of bone, a mineralized connective tissue

• Matrix of collagen (flexible) and minerals (hard)o Calcium, magnesium, phosphate ions

bone• Structure of bone - Repeating units called

osteons• Each osteon has a concentric layers of

mineralized matrix deposited around a central canal containing blood vessels and nerves that service the bone

• Arranged into osteons or Haversian systemso Store calcium saltso Withdraw

• Lacking calcium in diet• Create embryo

Blood• Matrix called plasma• Mainly water, salts and variety of

dissolved proteins• Suspended in plasma are

erythrocytes (red blood cells), leukocytes (white blood cells) and cell fragments called plateletso Red blood cells carry oxygeno White cells function in defense

against viruses, bacteria and other invaders

o Platelets aid in blood clotting