Test 1

What are bones?

Connective tissue

What are bones used for?

System of levers, hematopoiesis, homeostasis, mineral storage, energy storage, protection

Hematopoiesis

The process of producing new blood cells

Hypercalcemia

Medical condition involving abnormally high levels of calcium in your blood

Morphology

Study of the form and function of things

Congenital diseases

medical or health problem that is present at or before birth

Exoskeleton

Skeleton outside of body

Endoskeleton

Skeleton inside body

Organogenesis

The process where the three germ layers differentiate and fold into the internal organs and tissues of an organism

What are the three germ layers?

Ectoderm, mesoderm and endoderm

Neural chest cells

a vertebrate-specific population of multipotent embryonic stem cells that arise from the border of the neural plate and non-neural ectoderm during neurulation

Mesenchymal Stem Cells

multipotent adult stromal cells capable of self-renewal and differentiation into multiple cell types

What is included in the mesoderm?

Notochord, skeletal system, muscular system, muscular layer of stomach and intestine, excretory system, circulatory and lymphatic systems, reproductive system (Except germ cells), dermis of skin, lining of body cavity and adrenal cortex

What are the two types of bone in development?

Intramembranous and endochondral

Osteogenic cells

unspecialized stem cells that divide and develop into bone forming osteoblasts

What is another name for osteogenic cells?

Osteoprogenitor cells

Osteoblasts

Forms and builds new bone tissue

Osteocytes

Mature bone cells trapped inside hardened bone matrix

Bone lining

Inactive osteoblasts that cover surfaces where no active building or breakdown is happening

What do osteocytes do?

regulate bone structure, sense mechanical stress and direct ongoing tissue maintenance

Hematopoietic stem cell

immature cell found in bone marrow and blood that can develop into all types of blood cells

Myeloid cell

group of blood cells that form in bone marrow that lead to red blood cells, platelets and white blood cells

Monocyte

Large type of white blood cell which is front line against germs

Osteoclasts

Specialized large cell that breaks down and reabsorbs old or damaged bone tissue

Cartilage

Type of connective tissue

Chondrogenesis

The process of making new cartilage

Chondrogenic cells

Stem cells found in the inner layer of the perichondrium

Chondroblasts

Active, immature cells that build cartillage

Chondrocytes

Mature cells trapped inside small pockets called lacunae

Hyaline cartilage

cartilage containing type 2 collagen fibres

Where is hyaline cartilage found?

End of nose, rings around the trachea, bronchi

What produces collagen?

Osteoblasts, chondroblasts and fibroblasts

What is the function of collagen?

Allows mineralization

What are the types of connective tissue?

Blood, loose connective, adipose, cartilage, bone and dense

Resident cells

Permanent cells that live, function and remain locally within specific connective tissue

Extracellular matrix

Complex, non-cellular network of proteins and carbohydrates secreted by cells into the surrounding space

What are the two parts of the extracellular matrix?

Ground substance and fibres

Fibroblasts

Large flat cells with branching processes. Present in all the general connective tissues and the most numerous

What is responsible for secreting the ECM and collagen in most tissues?

Fibroblasts

Macrophages

Develop from monocytes engulf bacteria and cellular debris

Plasma cells

Function in immune response

Mast cells

Abundant alongside of blood vessels that supply connective tissue

Adipocytes

connective tissue cells that store triglycerides

White blood cells

Not in significant numbers in most connective tissue

Ground substance

Contains water and an assortment of large biomolecules

Fibres

Embedded in extracellular matrix between cells

Collagen

Strong resists tensile forces allows tissue flexibility

Elastic

Consists of protein elastin, can be stretched up to 150% of relaxed length without breaking

Reticular

Provide support in walls of blood vessels and form network around the cell in some tissues (Adipose tissue, nerve fibres)

What is the osseous tissue matrix made up of?

Organic (30% total with 90% type 1 collagen and 10% non-collagenous proteins), 10% water, 60% inorganic minerals in the form of hydroxyapatite

What makes up the organic portion of bone composition?

Type 1 collagen (90%) and non-collagenous proteins NCPs (10%)

What are the functions of Non-collagenous Proteins?

Produced by some cells, regulate mineralization, remodeling, cell to cell interactions, secreted at various stages of osteogenesis, can be root of pathology with increase/ decrease expression, increase calcium binding

Osteonectin

Binds calcium, allows proper organization of the bone matrix through contacts with the cellular surface

Osteocalcin

10% of the NCP of bone, also found in dentin, produced by osteoblasts

NCP

Non-collagenous protein

What is the action of parathyroid hormone?

increase blood calcium, increase bone resorption, increase bone formation

What is the action of oestrogen (and testosterone)?

Decreases bone resorption and increases bone formation (smaller effect)

What is the action of RANKL?

Increases bone resorption (forms osteoclasts)

What is the action of OPG?

Decreases bone resorption (Blocks RANKL)

What is the action of sclerostin?

Decreases formation (blocks Wnt signalling)

What is the action of nitric oxide?

Increases bone formation (Dilates blood vessels)

What is the action of Hypoxia?

Increases bone resorption (forms osteoclasts) and decreases bone (blocks osteoblasts)

What is the action of acidosis (low pH)?

Increases bone resorption (activates osteoclasts)

What is the action of pyrophosphate?

Decreases bone mineralisation

What is the action of strain or deformation?

Increase bone formation

What are the four types of cells present in bone tissue?

Osteogenic cells, osteoblast, osteocytes, osteoclasts

Osteogenic cells

Stem cells

Osteoblast

Bone forming cells

Osteocytes

Mature un-dividing osteoblasts embedded in matrix 90% of cells

Osteoclasts

Large multinucleated cells, responsible for the erosion of bone surface

What constitutes 80% of the total bone mass?

Compact bone

What are the structures of osteon?

Lamellae, lacunae, canaliculi, haversian canal

Where are osteons found?

In compact bone

Lamellae

Ring like layers of bone matrix

Lacunae

Tiny, fluid filled spaces or cavities scattered between the lamellae rings

Canaliculi

hair like canals of tunnels that radiate outward from the lacunae

Haversian canal

Central, vertical tunnel running through the middle of each osteon unit

Connective tissue

type of animal body tissue that supports, protects, binds and gives structure to other tissues and organs

What is reflective of tissue?

Anatomy

Osseous tissue

Mineralized connective tissues

Proximal epiphysis

End of the long bone close to the point of attachment

Epiphysis

End of a long bone

Diaphysis

Middle shaft of a long bone

Distal epiphysis

End of the long bone furthest from the point of attachment

Where is the most cortical bone in a long bone?

The shaft/ diaphysis

Metaphysis

Tapered neck of long bone

Periosteum

Covers all of the bone except the ends where we see cartilage

What is the function of periosteum

Provides bone with vascularization

How many layers does the periosteum have?

Two layers

Endosteum

Surface on inside of bone (NOT a membrane)

Function of endosteum

lines the internal surfaces of bones

Where is cortical bone primarily found?

In the diaphysis

What surrounds trabecular bone?

Cortical bone

What is the function of cortical bone?

Support and protection

Where is the most trabecular bone found?

At the metaphysis and epiphysis

What bones are majority of trabecular bone found in adults?

Vertebrae, ribs and iliac crest

What percent of bone is bone tissue?

25-30%

Are there osteons in trabecular bone?

No osteons

Where do trabecular bones get their blood supply?

From marrow

How are osteons arranged?

Parallel to the shaft