Chapter 6- Bones and skeletal tissues Flashcards
Chondro-
Cartilage
Osteo-
bone
Functions of bones (6)
- Support
- Protection
- Attachment point
- Storage
- Blood cell formation
- Hormone production
How do bones support the body
holds up the body and cradles organs- bone is second hardest substance produced by the body (teeth are the hardest)
Occurs in conjunction with skeletal muscle tissue
Which general areas of the body do the bones protect (2)
- Central nervous system- the skull protects the brain, the vertebrae wrap around the spinal cord
- Visceral organs- rib cage wraps around organs in thorax and the upper abdominal cavity
What attaches muscle to bone
skeletal muscle attaches to bone via tendons
How do the muscles use the bones to allow for voluntary movement?
Tendons allow the muscles to use the bones as levers. Shortening (contracting) muscle pulls on the tendon which pulls on the bone, producing movement.
What substances do bones store? (2)
Minerals- calcium
Fat- yellow marrow in the bones of adults
Hematopoiesis
formation of blood cells in red bone marrow
Which hormone is produced by bones?
Osteocalcin- regulates insulin release, glucose homeostasis, and energy expenditure
Before the osseous skeleton is formed, what 2 things is it composed of?
Before the osseous skeleton forms, it is composed of cartilage and connective fibers
Why is cartilage ideal for the skeleton before bone is formed?
Cartilage cells accommodate mitosis very well. Ground substance is viscous and makes it firm, but cartilage is still mostly water
Characteristics of all cartilage types (4)
- Strength and resilience- it can be compressed and return to original shape
- Cartilage is mostly water- contributes to flexibility
- No nerve supply and avascular
- Surrounded externally by perichondrium (tissue sheet)
Perichondrium
Tissue sheet that surrounds cartilage externally. Contains blood vessels and resists outward expansion of cartilage- prevents it from being too compressed
2 basic components found in all types of cartilage
- Chondrocytes
2. Extracellular matrix- has fibers, more viscous
Types of cartilage (3)
- Hyaline
- Elastic
- Fibrocartilage
Hyaline cartilage
Most abundant type of cartilage. Chondrocytes are spherical, contains collagen fibers
Where is hyaline cartilage typically found?
articular cartilage (forming joints), costal cartilage, respiratory cartilage, nasal cartilage
Elastic cartilage
Similar to hyaline, but contain more elastic fibers
Where is elastic cartilage typically found
Examples- external ear, epiglottis (like a trap door closing over the trachea when you swallow).
Fibrocartilage
Most compressible, great tensile strength- can support a lot of weight without damage
Contain rows of chondrocytes alternating with thick collagen bands
Where is fibrocartilage typically found
Examples- vertebral discs, knee, pubic symphysis (joint between pubic bones)
Types of growth of cartilage (2)
- Appositional
2. Interstitial
Appositional cartilage growth
laying down new cartilage on old cartilage
Cells in perichondrium deposit new matrix on top of preexisting cartilage, like stacking bricks
Occurs at surface, used for growth in width
Interstitial cartilage growth
growth from within
Associated with growth in length
Cells divide and secrete matrix in pre-existing cartilage
Occurs throughout tissue
Which 2 characteristics are used to classify bones?
- Location (axial, appendicular)
2. Shape (long, short, flat, irregular)
Axial skeleton
makes up long axis of body- skull, vertebral column, ribs
Appendicular skeleton
makes up limbs of body, girdles- pectoral and pelvic girdles, arms and legs
Important for production of skeletal muscle movement
Long bones
Long- longer than they are wide. They don’t necessarily have to be overall long in length- you are referring to the shape of the bone instead (the bones in the fingers are also long bones). Usually column shaped
Includes almost all limb bones
Short bones
cube shaped (have more equal dimensions in terms of width and height). Includes wrist and ankle bones as well as sesamoid bones.
Sesamoid bones
bone that forms in a tendon (the kneecap). Acts like a pulley allowing the tendon to slide over surrounding surfaces and reduces stress or pulling forces on the tendon.
Flat bones
thin, flat, curved
Sternum, scapulae, ribs, most cranial bones
Irregular bones
Vertebrae, os coxa
Don’t fit any of the previously mentioned shape categories
Which 2 elements do all bones contain?
- Compact bone
- Spongy (trabecular) bone
These components will be found in different amounts in different places
Compact bone
looks smooth and solid
Spongy (trabecular) bone
has open spaces with needle like pieces of bone called trabeculae (located on the inside of the bone).
Space between trabeculae is filled with red or yellow marrow in living bone
Where are trabeculae found in the greatest concentration?
Trabeculae are found in greatest concentration along lines of stress (that part of the bone is frequently put under pressure). Prevent the bone from twisting, bending, or even breaking.
Structure of flat, irregular, and short bone (3)
- Thin plate of spongy bone covered by compact bone- compact bone forms a spongy bone sandwich
- No well defined cavities for bone marrow
- Covered externally by bone membrane (periosteum)
Where is bone marrow found in flat, irregular, and short bone?
All bone marrow is found around trabeculae of spongy bone. There is no bone marrow cavity
4 similar features of long bones
- Diaphysis
- Epiphysis
- Membranes
- Vascularized and innervated
Diaphysis
bone shaft. Makes up most of the length of the long bone and is the cylinder portion
Characteristics of the diaphysis in long bones (3)
- Composed of compact bone “collar” with internal medullary cavity. Helps with bearing weight loads
- Medullary cavity filled with yellow marrow in adults
- Very thin layer of spongy bone separates the bone marrow from compact bone
Epiphysis
Bone ends that form joint surfaces. Irregularly shaped because these are the locations of articulation (joint formation). Composed of compact bone externally, spongy bone internally, and they are covered in hyaline cartilage
What 2 membranes are found in long bones?
- Periosteum
2. Endosteum
osteoprogenitor cells
Undifferentiated stem cells that are mitotically active (constantly reproducing)
Can remain as osteogenic cells or differentiate to form osteoblasts. They are found in the periosteum and endosteum
Periosteum
The membrane that covers the bone surface, except at joints. It is double layered:
outermost layer is fibrous (tougher, helps protect bone, prevents periosteum from tearing when bone bends), inner layer composed of osteoprogenitor cells
It is very well vascularized and innervated. If a bone is broken badly enough that it breaks the periosteum, the tear will contribute to the pain and bleeding experienced.
Endosteum
The membrane that covers the internal bone surface- trabeculae in spongy bone, canals in compact bone
Also contains osteoprogenitor cells- bone growth must occur on the inside of bone to balance out the growth occurring on the outside