Test Three Module 7 Flashcards
The skeletal system consists of: (4)
- The bones of the skeleton
- Cartilages between bones
- Ligaments connecting bones
- Connective tissues surrounding all of these
What are the 6 functions of the skeletal system?
- Support
- Protection (e.g. skull, ribs)
- Leverage for muscle contractions
- Storage of calcium, phosphate
- Storage of lipids (yellow bone marrow)
- Blood cell production (red bone marrow)
What is stored in the yellow bone marrow?
lipids
Bone itself is a _____?
tissue
Bone is formally called _____?
osseous tissue
Bone or osseous tissue is a type of _____ tissue?
supporting connective tissue
Osseous tissue has more extracellular matrix than _____?
cells
The extracellular matrix is the _____?
solid bone mineral
Bones can be classified and categorized by?
(Shape and location)
- Shape of individual bone
- How the bone tissue is organized in a specific location within a larger bone
Within an individual bone, the osseous tissue/bone can be organized into one of what two ways?
- Compact bone
2. Spongy bone
Compact bone is also known as?
- Dense bone
- Cortical bone
_____ bone is the outer layer of bones?
Compact
Ho much of compact bone can be space?
30%
In compact bone only 5-30% is ____ or ___?
pores or spaces
What are mostly the pores or spaces in compact bone?
Lacunae and canaliculi holding osteocytes
Compact bone consists of _____of bone grouped together?
cylinders
Each cylinder of bone is called an _____?
osteon
What is another name for a osteon?
Haversian system
Each osteon is made up of concentric rings called ______?
lamellae
Spongy bone is also called?
- Cancellous bone
- Trabecular bone
______ bone is the inner layer of all bone?
Spongy
Spongy bone is 30-90% _____ created by a lattice of rods and plates?
pores
_____ and ____ travel through the spaces in spongy bone and the rest of the space is often filled with re or yellow bone marrow?
blood vessels and nerves
In spongy bone, _____ are the small projections of bone that make up the solid part of spongy (trabecular) bone?
Trabeculae
Long bones have an additional feature, a ______?
Cavity
What is a cavity?
Empty of bone but filled with other tissues
In long bones, the ______ is where additional red or yellow bone marrow is kept?
Medullary cavity
Where else in bone marrow found?
It is kept between trabeculae of spongy bones
In childhood the medullary cavity is filled with ______ bone marrow?
Red bone marrow
In adulthood all the marrow in the medullary cavity has switched over to _____ bone marrow?
Yellow bone marrow
The spongy bone around the medullary cavity still has some _____ marrow in between its trabeculae?
Red marrow
_____ marrow is a respiratory of specialized mesenchymal stem cells that have specialized into hematopoietic stem cells?
Red bone marrow
In red bone marrow, the ______ stem cells divide and specialize into all the red and white blood cells that will leave bone marrow and enter the blood?
hematompoietic stem cells
Most of the developing hematompoietic stem cells will specialize into _____ blood cells, which is why red bone marrow is red?
red blood cells
Mesenchymal stem cells can develop into any connective tissue cell type, but _____ stem cells have specialized into a stem cell that will only develop into blood cells?
hematopoietic
_____ bone marrow is a repository of mostly adipose tissue (fat)?
Yellow bone marrow
As a person ages, the hematopoietic stem cells of red bone marrow are replaced with _____ tissue in the medullary cavities of all the long bones, converting red bone marrow to yellow bone marrow?
adipose tissue
Adipose tissue is vaguely _____ colored, which is why it is called yellow bone marrow?
Yellow
In adults red bone marrow with hematopoietic stem cells remains only in spongy bone and only in a few locations: (4)
- In the spongy bone at the ends (heads) of the femur and tibia bones.
- In the spongy bone of flat bones like the skull bones and ribs.
- In the spongy bone of the coxal bones.
- In the spongy bone of the vertebrae.
Bones are osseous tissue, the densest type of _____ connective tissue?
supportive connective tissue
Like all connective tissue, _____ tissue consists of interspersed cells in an elaborate extracellular matrix?
osseous
Two thirds of bone extracellular matrix is _____?
Hydroxyapatite
Hydroxyapatite is _____ that has reacted with _____ to form crystals of hydroxyapatite?
Calcum phosphate and calcium hydroxide
The _____ binds up other calcium salts and other ions and incorporates them into the now solid extracellular matrix?
hydroxyapatite
One third of bone extracellular matrix is _____?
collagen protein fibers
The hydroxyapatite crystals deposit on the _____, creating a solid matrix around them?
collagen protein fibers
What are the two things that make up bone extracellular matrix?
hydroxyapatite and collagen protein fibers
Cells make up only __% of bone mass?
2%
Bone contains what 4 types of cells?
- osteocytes
- osteolasts
- osteprogenittor cells
- osteoclasts
_____ are mature bone cells that maintain the bone matrix?
osteocytes
Where are osteocytes found?
Throughout the bone interior, completely surrounded by solid extracellular matrix
Cytoplasmic extensions from one osteocyte meets up and is joined via _____ to a cytoplasmic extension from a neighboring osteocyte?
gap junctions
Osteocytes are found in openings in extracellular matrix called _____?
lacunae
If the osteocytes were not in _____, the mineral extracellular matrix would crush them?
lacunae
What are canaliculi?
Canaliculi are not the cellular extensions; they are the tunnels the extensions are found in.
Osteocytes are found between _____ (concentric rings) of osteons and trabeculae?
lamellae
_____ do not divide?
osteocytes
What are the main functions of osteocytes?
+To maintain protein and mineral content of nearby existing extracellular matrix by both removing and replacing nearby extracellular matrix components.
+Osteocytes alter the contents of the bone extracellular matrix on small-scale; other bone cells remove and replace bone mineral on a larger scale.
_____ are immature bone cells that secrete extracellular matrix compounds and build new extracellular matrix in a process called osteogenesis?
Osteoblasts
_____ are located in the periosteum the membrane surrounding the exterior of bones and in the endosteum lining medullary canals, central canals, and spongy bone?
Osteoblasts
Osteoblasts first lay down _____?
osteoid
_____ is extracellular matrix produced by osteoblasts, with collagen and phosphate, but not any calcium?
osteoid
Osteoblasts that have secreted enough extracellular matrix to become surrounded by bone mineral and collagen convert to _____?
osteocytes
Osteoblasts just _____ bone, don’t actively remove and replace it like osteocytes?
build
What does osteoid lack?
calcium
_____ is a somatic stem cell that divides to produce two daughter cells, one that remains an osteoprogenitor cell, the other specializes into an osteoblast. The osteoblast will eventually specialize into an osteocyte?
osteoprogenitor cells
Osteoprogenitor cells assist in _____ repair, but not much in normal growth of intact bones?
fracture
_____ stem cells can be converted to osteoprogenitor cells?
mesenchymal stem cells
What is another name for osteoprogenitor cells?
osteogenic cells
_____ cells are giant, multi-nucleate cells?
osteoclast
_____ cells secrete protein-digesting enzymes that break down the collagen fibers in bone extracellular matrix?
Osteoclast
_____ cells also secrete acids that release the calcium and phosphate in bone extracellular matrix dissolving the bone mineral?
Osteoclast
Osteoclast _____ small portions of bone?
collapse
This process of using osteoclasts to collapse small portions of bone is called _____ or ____?
osteolysis or bone resorption
_____ are not derived from osteoprogenitor cells, but derive from the same hematopoietic stem cells that produce macrophages (white blood cells that engulf & digest pathogens)?
osteoclasts
Where are osteoclasts found or located?
In the inner layer o the endosteum lining the medullary cavity, central canal, and trabeulae
where are osteocytes found or located?
In the lamellae of compact and spongy bone
Where are osteoblasts found or located?
in the periosteum lining the outside of bones and in inner layer of the endosteum?
Where are osteoprogenitor cells found or located?
in the periosteum lining the outside of bones and in the inner layer of the endosteum
What are the two “membranes” that line bones?
Periosteum and endosteum
Periostuem lines _____ bones?
outside
Endosteum lines_____ bones?
Inside
Both “membranes”, periosteum and endosteum consist of a layer of _____ over a layer of bone cells without the bone extracellular material around them?
irregular dense connective tissue proper
The _____ on the exterior surface of bones is a layer of irregular dense connective tissue proper + a layer of bone cells?
periosteum
The _____ covers the surfaces of all bones regardless of location or bone type?
periosteum
What are the functions of periostium? (3)
+It isolates bone from surrounding tissues.
+Its outer layer of irregular dense connective tissue proper provides a route for blood vessels, lymph vessels, nerves to connect to bone.
+Its inner layer of cells (not surrounded by bone mineral) participates in bone growth and repair because it is a layer of osteoprogenitor cells and osteoblasts – bone cells which build new bone mineral.
The _____ is attached tightly to the bone underneath it and allows tight attachment of tendons and ligaments to bones due to its perforating fibers?
periosteum
What three things do perforating fibers connect?
bone, periosteum, ligaments/tendons
What are perforating fibers?
The collagen fibers of the periosteum that extend out of the periosteum and connect
These perforating fibers provide a very strong attachment between bones and their _____ or _____?
ligaments or tendons
The _____ is the layer of irregular dense connective tissue proper plus a layer of bone cells found inside bones?
endosteum
What does the endosteum line and cover? (3)
+It lines the medullary cavity (contains marrow) of long bones.
+It covers trabeculae of spongy bone.
+It lines central canals of compact bone osteons.
What is the main difference between endosteum and periosteum/
endosteum’s inner layer of bone cells has osteoclasts,(not found in periosteum), as well as osteoprogenitor cells and osteoblasts (are found in periosteum.).
_____ is active in bone growth, bone repair, and bone remodeling because its inner layer houses osteoclasts as well as osteoblasts and osteoprogenitor cells ?
Endosteum
_____ outside bones only have osteoprogenitor cells and osteoblasts next to its irregular dense connective tissue proper layer?
periosteum
What two cells are involved in bone remodeling?
Osteoblast and osteoclast
_____ Dismantle some bone existing extracellular matrix, but _____ deposit some new bone extracellular matrix around existing extracellular matrix?
osteoclast / osteoblast
What happens during bone remodeling?
Bones extracellular matrix is removed and then immediately replaced
When bone _____ is maintained the extent of bone dismantling by osteoclasts is balanced by the extent of bone deposition by osteoblasts?
homeostasis
In a young adult, approximately _____ of all bone is removed and replaced each year without significant changes in total bone mass?
1/5th
Removal of bone by _____ is balanced by equal amounts of new bone formation by ______?
osteoclasts / osteoblasts
_____ such as lead, strontium, cobalt, uranium, plutonium can be “accidentally” incorporated into new bone if too abundant in the body?
heavy metals
_____ are also known for building brand new bone?
osteoblasts
_____ do not dismantle any extracellular matrix, only add to it?
osteoblasts
If osteoblast bone deposition outpaces osteoclast bone removal the net result is _____?
bone growth
osteoblast are found both in _____ outside of bone and in the _____ inside of bone, so growth can occur outwards and inwards?
periosteum and endosteum
_____ are also involved in the dismantling existing bone?
osteoclasts
Some bones change shape during growth so _____ needed to dismantle unneeded sections?
osteoclasts
If the body’s calcium ion levels are too low, osteoclasts will be signaled to dismantle bone to release _____ that can be taken up by cells throughout the body that need it?
calcium
If osteoblast activity drops below osteoclast activitym there is _____?
net bone loss
_____ bones becomes thicker and stronger?
heavily stressed (ex. exercise)
The _____ induces osteoblasts to build extra bone?
stress
Bone _____ quickly, up to one third on bone mass can be lost in a few weeks of inactivity probably because of lower _____ activity?
degenerates and osteoblast
Compact bone mostly consists of _____ of bone grouped together?
cylinders
Each cyclinder in compact bone is called an ______?
Osteon or haversion system
Interior of compact bone consists of many _____ stacked on top of each other?
osteons
The bone in each osteon is arranged in concentric circles, each circle is a _____?
concentric lamella
Where are osteocytes found in osteons?
they are found at the edges of lamellae
What is the central canal?
It is the tunnel in the center of each osteon
What does the central canal contain?
Blood vessels and nerves that penetrate the compact bone
What lines the central canal?
Endosteum
What are perforating canals?
they travel perpendicular to the central canal and carry blood vessels into deeper bone, eventually reaching spongy bone and the medullary cavity in the center of long bones
Within the concentric lamellae of osteons, the collagen protein fibers in the bone ecm ______?
run up the osteon and run at a slant
The partially dismantled osteons are called _____?
interstitial lamellae
Intact osteons are partially dismantled by _____ creating irregularly shaped interstitial lamellae?
osteoclasts
What are interstitial lamellae?
Partially dismantled osteons
On the outer surfaces and the most inner surfaces of bones is _____ that circle the entire bone?
circumferential lamellae
_____ bone does not have true osteons?
spongy bone
The tissue forms an open web like network of _____ which are the threads that make up the solid portions of spongy bone?
trabeculae
Each _____ has concentric rings of lamellae similar to the make up of an osteon but without a central canal?
trabeculae
What do trabeculae lack that is found in osteons?
Central canals
Trabeculae have no ____ or no _____?
central canal or blood vessels
But the spaces between trabecular have _____, _____, and _____ that travel from perforating canals in compact bone?
blood vessels, lymph vessels, and nerves
Trabeculae are covered with ____ the connective tissue + bone cells wrapper that also line central canals in compact bone?
endosteum
The remaining spaces (not filled with blood vessels, lymph vessels, or nerves) between trabeculae are filled with _____ ?
bone marrow
Initially _____ bone marrow fills the spaces in spongy bone, where new red and white blood cells are formed?
red
In later life, some red bone marrow is replaced with _____ which mostly consists of fat in the form of adipocytes?
yellow bone marrow
What are some nutritional factors needed for normal bone growth? (3)
+A dietary source of calcium and phosphate salts
+Plus small amounts of magnesium, fluoride, iron, and manganese
+and various vitamins
What vitamin deficiency causes rickets?
Vitamin D deficiency
How do we get vitamin D3?
it is produced in skin using UV light or obtained through diet
What is vitamin D3 use?
Its used to produce the hormone calcitriol, which allows the body’s cells to take up ca2+ efficiently
Why do bone cells need to take up Ca2+?
in order to deposit it in osteoid and solidify into true bone
What is rickets?
When developing bones of legs do not have enough calcium to solidify entirely, bend under weight of body
What is required for collagen sythesis?
vitamin C
What is required for stimulation of differentiation of osteoprogenitor cells in osteoblast?
vitamin C
What cause scurvy?
Vitamin C deficiency
What are symptoms of scurvy?
Bleading, hair and tooth loss, joint pain, fatigue, and eventually death
What stimulates osteoclast activity, necessary for proper bone remodeling?
vitamin A
What vitamin deficiency causes blindness?
vitamin A
Vitamin A also affects ____ but eyes are more noticeably affected?
bones
What vitamin is necessary for proper osteoblast activity?
vitamin K
What vitamin deficiency cause hemophilia and lower bone density?
vitamin K
______ deficiency results in less bone growth, but it is also necessary for blood clotting, so a _____ deficiency is more noticeable for producing excess bleeding?
vitamin K
What 5 hormones are needed for bone growth and maintenance?
- Calcitriol
- Growth hormones
3, Thyroxine - Estrogens and adrogens
- Calcitonin and parathyroid hormone
Where is calcitriol produce and from what?
produced from vitamin D3 in kidneys
What does calcitriol help?
helps in calcium, phosphate absorption in digestive tract
Where is growth hormone produced?
in pituitary gland, stimulates protein synthesis & cell growth in all cells, including osteoblasts
Where is thyroxine produced?
in the thyroid gland and stimulates osteoblasts
What do estrogens and androgens do?
Stimulate osteoblast
What do calcitonin and parathyroid hormone do?
regulate calcium and phosphate levels
As an embryo starts developing, most of the bones in the skeleton are initially made out of _____?
hyaline cartilage
When does cartilage start to gradually convert from cartilage to bone?
after the embryo develops into a fetus
What are most bones initially made from during fetal development?
cartilage
The fetus’ cartilage is replace by bone in a process known as _____?
endochondral ossification
What are the 6 steps of endochondral ossification?
- A skeletal component is made of cartilage.
- Chondrocytes (cartilage cells) die.
- Osteoprogenitor cells move in.
- Osteoprogenitor cells convert to osteoblasts.
- Osteoblasts replace cartilage extracellular matrix with bone extracellular matrix.
- Osteoblasts surround themselves with bone mineral and convert to osteocytes.
Growth in long bone is both in ______ and _____?
width and length
To allow lengthwise growth in long bones there is an _____?
epiphyseal plate
Where are the epiphysis?
on either end of the long bone
Where is diaphysis?
on the shaft of the bone, between the 2 epiphysis on each end of long bone
The _____ is a band of cartilage near each end (epiphysis) of any long bone? AKA the growth plate?
epiphyseal plate
After birth, the _____ is the site at which length is added to long bones?
epiphyseal plate
What are the 3 steps that the epiphyseal plate allow long bone to add length after birth?
- At the side of the epiphyseal plate closer to the end of the bone, chondrocytes in the cartilage produce more cartilage.
- On the side of the epiphyseal plate closer to the shaft of the bone, osteoblasts remove cartilage and replace it with bone mineral (called calcification).
- It lengthens the bone without lengthening the epiphyseal plate.
Once a person reaches adulthood and stops growing, the entire epiphyseal plate is converted to _____ (calcified) and all that remains is an epiphyseal line, still visible in X-rays or by direct examination?
compact bone
What are some of the bones that never start out as cartilage and develop later by intramembranous ossification?
flat bone of skull , clavicle, and mandible
Name the 6 steps of intramembranous ossification?
- Dense connective tissue proper forms in the region that will later be bone.
- Messenchymal stem cells from the connective tissue convert to osteoprogenitor cells that line the inner layer of the connective tissue.
- The osteoprogenitor cells convert to osteoblasts.
- The osteoblasts lay down bone mineral.
- Osteoblasts surround themselves with bone mineral and convert to osteocytes.
- Most of the connective tissue is replaced with bone, but the outer layer becomes periosteum.
What is osteopenia?
The condition where bone density is less the optimal
Bones become thinner and weaker with age s part of the _____?
normal aging process
When do most people start to experience osteopenia?
between the ages of 30 and 40
Why does osteopenia happen?
Because osteoblast activity starts to drop and less new bone is made, but osteoclast activity remains steady and bone removal starts outpacing bone productions
Once osteopenia has started, women lose __% of bone mass per decade and men lose __%?
8% and 3%
What is most affected by osteopenia?
the ends of long bones, the vertebrae, and jaws
What are some results of the ends of long bones, the vertebrae, and jaws being the most affected by ostoepenia?
Fragile bones, reduction in height, and tooth loss
What is not a symptom of osteopenia?
Kyphosis or dowager humps
What is osteoporosis?
severe bone loss that adversely affects normal function
What age does osteoporosis mostly occur?
over age 45
What is osteoporosis linked to?
Linked to the drop in estrogens (in women post-menopause) and androgens (in men not dramatic until post-60s) with age
_____ is extreme osteopenia?
Osteoporosis
What test, test bone mineral density?
DEXA test
What do angrogens and estrogens stimulate?
osteoblast
So when androgen and estrogen levels drop with age, ____ keep removing bone, but osteoblasts are slower to replace it?
osteoclasts
What can cause kyphosis or dowager humps?
osteoporosis weakening the vertebrae in backbone and leading to them cracking and compressing
______ can weaken vertebrae in backbone and lead to them cracking and compressing?
osteoporosis
What is kyphosis?
An extreme forward rounding of the back
Dowager humps are more common in _____ than _____ because osteoporosis is more common in older _____?
women / men / women
