Chapter 7 Flashcards
The skeletal system is composed of…
Bones, cartilage, and ligaments joined tightly together to for a strong, flexible framework for the body.
The forerunner of most bones in embryonic and childhood development is…
Cartilage
What are the tissues that compose the skeleton?
Cartilage covers…
Many joints surfaces in the mature skeleton.
What are the organs that compose the skeleton?
What are the 8 functions of the skeletal system?
Support, protection, movement, electrolyte balance, acid-base balance, blood formation, hormone secretion, and triglyceride storage.
What is the support function of the skeletal system?
Limb bones and vertebrae support the body. Jaw bones support teeth. Some bones support viscera.
What is the protection function of the skeletal system?
Cranial bones protect the brain, vertebrae bones protect the spinal cord, the bones in the thoraces protect the heart, lung etc. The pelvis protects the pelvic cavity organs.
The only organs not protected by bone are the…
Abdominal organs
What is the movement function of the skeletal system?
Limb movements, breathing, and other movements depend on bone
What is the electrolyte balance function of the skeletal system?
Bones are a store house of minerals, especially calcium and phosphorus
What is the acid-base balance function of the skeletal system?
Buffers blood against large pH changes by altering phosphate and carbonate salt levels to maintain an acid-base balance
Phosphate is an…
Intracellular buffer
Carbonate is an…
Extracellular buffer
What is a buffer?
A chemical that resists changes to pH
What is the blood formation function of the skeletal system?
Red bone marrow (red in color) is the chief producer of blood cells
What is the hormone secretion function of the skeletal system?
Bone cells secrete hormones that affect action of insulin and moderate the stress response
What is the triglyceride storage function of the skeletal system?
Most areas of the bone, instead of forming the blood cells, get replaced into fat
Bone that gets replaced into fat is called…
Yellow bone marrow
If there is a need for increased blood cells, the yellow bone marrow can…
Change itself into red bone marrow
What is bone (osseous tissue)?
Connective tissue with the matrix hardened by calcium, phosphate and other minerals
What is mineralization/calcification?
The hardening process of bone
What is the hardest substance in the body?
Tooth enamel
What is the second hardest substance in the body?
Bone
Why are bones classified as organs?
Because they are made up of more than 2 tissues
What is bone made up of?
It is made up of blood, bone tissue, bone marrow, cartilage, adipose tissue, nervous tissue, and fibrous connective tissue
How are bones classified?
Bones are classified on the bases of their length, meaning how long or tall they are
Distinguish between bone as a tissue and bone as an organ.
What are the general features of a long bone?
They are longer than wider
What are some examples of long bones?
Humerus, radius, ulna, femur, tibia, fibula, metacarpals, metatarsal, and phalanges
What are the general features of a flat bone?
They are thin curved plates
What are some examples of flat bones?
Parietal bones of skull, sternum, scapula, ribs, and hip bones
Bones that don’t fit the long bone and flat bone categories are either…
Short bones or irregular bones
What are the general features of short bones?
Approx. equal length and width
What are some examples of short bones?
Bones of wrist and ankle
What are the general features of irregular bones?
Elaborate shapes. The bones don’t fit in the other categories. They are neither long, short, or flat.
What are some examples of irregular bones?
Vertebrae and some skull bones.
What are the general features of sesamoid bones?
They look like a sesame seed magnified 1000x.
What is an example of a sesamoid bone?
Patella organ kneecap
What the general feature of sutural bones?
Wherever these cranial bones come together (where those zigzag lines come together), when it gets replaced those are called sutural bones.
Where are sutural bones found?
Found in the sutures, especially in the areas of the cranial bones.
Much of a long bone is composed of an outer shell of dense white osseous tissue called…
Compact, dense or cortical bone.
What does the outer shell of a long bone enclose?
A space called the marrow (medullary) cavity.
What does the marrow (medullary) cavity contain?
Bone marrow
How is compact (dense or cortical) bone packed?
It it tightly/closely packed.
Does compact (dense or cortical) bone have a lot of empty spaces?
No, it doesn’t have a lot of empty spaces
At the ends of the bones, what is the central space occupied by?
Spongy bone
What is spongy bone?
Loosely organize bone tissue.
What does spongy bone look like?
It looks like a sponge. It has lots of empty spaces.
Where is spongy bone found?
Found in the center of ends and center of shaft of long bones, and the middle of nearly all other bones.
What does spongy bone appear to be?
It appears to be irregular, but it is not.
What is spongy bone covered by?
Durable compact bone.
How much of the skeleton is compact bone by weight?
Three-fourths
How much skeleton is spongy bone by weight?
One-fourth
What would happen if bone was made up of all compact bone?
The bone would be so dense that we wouldn’t be able to walk. It would be too heavy to move.
What does physis mean?
Growth
What is the shaft of a long bone called?
Diaphysis
What is diaphysis?
A long cylindrical tubular shaft that provides leverage.
How much of the diaphysis is made up of compact bone?
The outer third layer
What is on either side of the diaphysis?
Elongated expanded ends called epiphysis.
What does epiphysis provide?
Strengthens the joint and provides added surface area for the attachment of tendons and ligaments.
The joint surface where one bone meets another is covered with…
A layer of hyaline cartilage called articular cartilage.
What does cartilage enable a joint to do?
Move more easily than it would if bone rubbed directly against each other.
Externally, what is a bone covered with?
Periosteum
What is periosteum?
A tough surface membrane.
What is periosteum made up of?
It is made up of 2 layers and perforating fibers.
What are the 2 layers of periosteum?
Outer fibrous layer of collagen and inner osteogenic layer of bone-forming cells.
What do periosteum perforating fibers do?
They penetrate the underlying bone matrix.
What does the periosteum provide?
It provides strong attachment and continuity from muscle to tendon to bone.
Is articular cartilage covered by periosteum?
No
What is periosteum important for?
The growth of bone and healing of fractures.
What is endosteum?
It is a thin layer of reticular connective tissue.
What does endosteum line?
It lines marrow cavities and all internal bone surfaces.
What are the functions of flat bones?
Flat bones protect delicate organs such as the brain and heart, and form brood surfaces for muscle attachment, such as the scapula and hip bones.
Flat bones have a _______ like structure.
Sandwich
What is the sandwich like structure of flat bones?
Inner and outer tables of compact bone enclosing layer of spongy bone in between.
What is the sandwich like structure of flat bones in the cranium called?
Diploe
What is diploe?
It’s the spongy middle layer.
What does the diploe do?
It absorbs shock.
What are the 4 types of bone cells?
Osteogenic cells, osteoblasts, osteocytes, and osteoclasts.
What are osteogenic cells?
Stem cells
Where are osteogenic cells found?
They are found in endosteum and the inner layer of the periosteum.
What do osteogenic cells make up?
They make up the bone structure.
What do osteogenic cells arise from?
They arise from embryonic mesenchyme.
What is the function of osteogenic cells?
They multiply continuously (undergo cell division), make other bone cell types, and give rise to osteoblasts.
What can osteogenic cells transform into?
Osteoblasts
What are the only cells capable of dividing and producing more bone cells?
Osteogenic cells
What are osteoblasts?
Bone-forming cells
Where are osteoblasts found?
They are found in the endosteum and the inner layer of the periosteum.
What type of cells are osteoblasts?
Cuboidal epithelium
What is the function of osteoblasts?
They make ECM for bone. They make ground substance for bone, and make the fibers needed for bone, especially collagen fibers.
What process do osteoblasts perform?
Osteogenesis
What is osteogenesis?
Synthesize soft organic matter of matrix and promote its mineralization.
What does stress on osteoblasts simulate?
It stimulates osteogenic cells to multiply rapidly and increase the number of osteoblasts to reinforce bone
What substance do osteoblasts secrete?
A hormone called osteocalcin.
What is the function of osteocalcin?
It stimulates insulin secretion of the pancreas and increases insulin sensitivity of the adipose (fat cells) and limits its growth.
What can osteoblasts mature into?
Osteocytes
What are osteocytes?
Former osteoblasts that have become trapped the the matrix they deposited. They maintain ECM for bone.
What does it mean that osteocytes maintain ECM for bone?
This means that they make sure that nutrition is received and that waste products are removed.
How do osteocytes maintain ECM for bone?
Osteocytes talk to other osteocytes. However, they cannot move from one place to another so put out their extensions that look like little canals called canaliculi.
Who do osteocytes give their waste to?
Blood vessels
What is lacunae?
Tiny cavities where osteocytes reside. Little lakes.
What are canaliculi?
Little channels that connect lacunae.
What do canaliculi also act like? What is the function?
Strain sensors. They produce biochemical signals that regulate bone remodeling when we exercise.
What happens when an osteocyte says that the matrix isn’t being maintained?
The osteocytes will send messages to the osteoclasts. They will come and destroy the bone. They eat the area where the matrix isn’t being maintained then osteoblasts will deposit the matrix.
Some osteocytes _____ bone matrix while others ______ it.
Reabsorb, deposit
How do osteocytes act as strain sensors?
When stressed they produce biochemical signals that regulate bone remodeling.
What is bone remodeling?
Adjustments in bone shape and density to adapt to stress.
Osteoblasts and osteocytes are also what type of important cell?
Endocrine cell