TISSUE TYPES

TISSUE TYPES We define “tissue” as “groups of cells that are similar in structure or function”. There are 4 main types of tissue.

EPITHELIAL TISSUE Makes up linings, coverings, and glandular tissue Primary functions include absorption, filtration, and secretion Cells have no direct blood supply, they instead depend on diffusion from connective tissue capillaries

EPITHELIAL TISSUE One free edge exposed to the exterior of the body or interior of a body cavity is called the apical surface. Bottom edge bordering basement membrane is called basal surface. The basement membrane is a structureless material secreted by cells

EPITHELIAL TISSUE We categorize epithelial tissue based off of 2 factors: Relative number of layers The shape of the cells

SIMPLE EPITHELIAL TISSUE Simple Epithelial Cells have one layer of cells and their functions include: absorption, secretion, filtration Simple Squamous Epithelium Forms membranes where rapid exchange of substance occurs Air sacs in lungs, capillaries Simple Cuboidal Epithelium Found mainly in glands and ducts Simple Columnar Epithelium Houses goblet cells that secrete mucous Lines the digestive tract

STRATIFIED EPITHELIAL TISSUE Stratified Epithelial Tissue is 2 or more cell layers thick, and is mainly used for protection Stratified Squamous Epithelium: Most common. Usually several layers of cells. Found in areas that get a lot of friction or abuse Around the mouth, esophagus, and outer layer of the skin Stratified Cuboidal & Stratified Columnar Epithelium: Found in the ducts of large glands Rare

EPITHELIAL TISSUE Endocrine Exocrine Transitional Epithelium Cells form organ linings, and can stretch an slide past each other so organs can change shape. Glandular Epithelium Cells make up your glands. Endocrine Glands secrete hormones directly into the blood stream Exocrine Glands secrete into ducts that go to the surface, like sweat and tears. Endocrine Exocrine

CONNECTIVE TISSUE Connects body parts Most abundant tissue in the human body Extremely well vascularized Made up of different cell types and varying amounts of extracellular matrix

CONNECTIVE TISSUE The Extracellular Matrix is made up of extracellular molecules secreted by cells, providing structure and biochemical support to the cells around it.

CONNECTIVE TISSUE Blood Bone There are 5 main types of connective tissue Bone Dense Connective Tissue Cartilage Loose Connective Tissue Blood

CONNECTIVE TISSUE BONE Cells sit in lacunae cavities surrounded by a hard matrix of calcium and collagen fibers

CONNECTIVE TISSUE Cartilage Less hard and more flexible than bone Hyaline Cartilage Elastic Cartilage Fibrocartilage

CONNECTIVE TISSUE Dense Connective Tissue Matrix of collagen fibers with rows of fibroblasts Tendons (muscle to bone) Ligaments (bone to bone)

CONNECTIVE TISSUE Loose Connective Tissue – soft, with more cells and less fibers Adipose Tissue – used for fuel, insulation, and forms subcutaneous tissue beneath the skin Areolar Tissue – cushions and protects body organs, keeps them in place, and connects skin to muscle

CONNECTIVE TISSUE Blood Transport for cardiovascular system Transports oxygen Transports white blood cells from bone marrow

Muscular Tissue Skeletal Muscle Long and striated Used for voluntary movement Can have multiple nuclei

Muscular Tissue Cardiac Muscle Heart only Striated, branching cells that interlace and are filled with gap junctions that help ion movement for rapid electrical flow

Muscular Tissue Smooth Muscle No striations Only one nucleus Lines hollow organs Helps with motion

Muscular Tissue

NERVOUS TISSUE NEURONS receive information (stimulation) and send information (reaction)

NERVOUS TISSUE The Spinal Cord runs inside the vertebral column and is very heavily protected by both bone and fluid to keep it safe and absorb impact. All the nerves in the body stem from the spinal cord.

NERVOUS TISSUE

NERVOUS TISSUE The brain is the control center for the nervous system, regulating and controlling everything the body does. It is also where all your memories are stored.

Nervous Tissue is also responsible for the regulation of TISSUE REPAIR

NERVOUS TISSUE Tissue Repair, Stage 1 - Inflammation Swelling of tissue Feeling of warmth Pain and redness while repair starts Area flooded with blood to deliver white blood cells White blood cells destroy and remove unrepairable cells and bacteria in the area

NERVOUS TISSUE Tissue Repair, Stage 2 - Regeneration Mitotic rate increases New cells put in place Begins while cleanup is still in process Initial repair done by fibroblasts Fibroblasts lay down collagen fibers to stabilize tissue

NERVOUS TISSUE PUS When a foreign body is detected (like bacteria) and an infection starts, the body signals for NEUTROPHILS (fast-acting white blood cells) to attack. Bacteria fights back, killing off neutrophils as they attack. Pus is an accumulation of dead neutrophils.