Chapter 6 Flashcards
What does the Skeletal System include?
- Bones of skeleton
- Cartilages
- Ligaments
- Connective Tissue
What are the functions of the Skeletal System?
- Support
- Storage of minerals (Calcium (very important) & Lipid (yellow marrow (store little bit of fat))
- Blood Cell production ( Red marrow (cavities of bones inside))
- Protection
- Leverage (force of motion(bones are levers of our muscles))
Classification of Bones:
How are bones Identified by?
- Shape
- Internal Tissues
- Bone Markings
What are the 5 different bone shapes?(w/ example for each one)
- Long Bones - Humerus, Femur, Tibia
- Flat Bones - Parietal bone
- Irregular bone - Vertebra
- Short bones - Carpal bones
- Sesamoid bones - Patella
Long Bones - Femur
- Diaphysis - the shaft
- Epiphysis - Wide part at each end/ articulation with other bones
- Metaphysis - where diaphysis and epiphysis meet
bone ( OSSEOUS ) Tissue
- Dense, support connective tissue
- Contains specialized cells
- Produces solid matrix of calcium salt deposits
- Around collagen fiber ( makes shatter proof )
Bone Matrix Minerals ( what are they made up of)
2/3 bone matrix is calcium phosphate (Ca3PO4)2
1/3 protein fibers (collagen)
Bone Cells(how much mass % do they make up)
only makes up 2%
- Osteocytes
- Osteoblasts
- Osteoclasts
Osteocytes (what do they do)
- mature bone cells that maintain bone metrix (b y providing nutrients)
- help repair damaged bones
- do not divide
Osteoblasts (what do they do)
- they make bone
- immature bone cells that secrete matrix compounds (OSTEOGENESIS) new formation of bones. Makes bone tissue of the body
Osteoid( what is it)
Matrix produced by osteoblasts, but not yet calcified to form bone
- Osteoblasts surrounded by bone become Osteocytes
Osteoclasts (what they do )
- dissolves existing bones (if no underlying condition (its a good thing))
- gains, multinucleate cells
- dissolves bone matrix and release stored minerals (osteolysis (dissolving of bone))
Osteoclasts (how they dissolve?)
Secrete acids and protein0digesting enzymes.
- Body is in control how much bone to dissolve
Homeostasis (with bones)
Bone building(by osteocytes & osteoblasts) and bone recycling (osteoclasts) must balance:
= more breakdown than building, bones become weak
- Exercise causes osteocytes to build bone
- weight barring (besides swimming because no subject to gravity)
What’s the difference between compact bone and spongy bone?
Compact bones are dense and Spongy bones are much more delicate
Osteon
associated with compact bone
- basic unit mature
- osteocytes are arranged in concentric lamellae
- around a central canal (allows) containing blood vessels
Spongy Bone (associated with?)
-Associated with Trabeculae (= spongy)
-does NOT have osteons
- Metrix forms an open network of trabeculae
- Trabeculae have NO blood vessels
Red Marrow (what is it)
Space between trabeculae is filled with RED BONE MARROW:
- has blood vessels
- forms red blood cells
- supplies nutrients to osteocytes
Yellow Marrow (what is it)
In SOME bones, spongy bone holds yellow bone marrow:
- is yellow because it stores fat
its yellow because of the fat
Difference of Periosteum and Endosteum
- Compact bone is covered with membrane
= PERIOsteum on the outside(has alot of pain nerves)
= EDO on the inside (lines the marrow cavity)
Endosteum
an incomplete cellilar layer:
- lines marrow cavity and central canals
- covers trabeculae of spongy bone
- contains osteoblasts, osteoprogenitor cells, and osteoclasts.
- active in bone growth and repair
Skin cells are instructions to make another cell
Bone Development ( when do you fully grow bones and two )
what’s osteogenesis and ossification
- Human bones grow (vertically) until about age 25
- Osteogenesis- bone formation
- Ossification: the process of replacing other tissues with bone
Remodeling
the adult skeleton:
- maintains itself.
- replaces mineral reserves
remodeling
- recycles and renews bone matrix
- involves the 3 O’s - osteocytes, osteoblasts, & osteoclasts
Effects of exercise on Bone
- mineral recycling allows bones to adapt to stress
- heavily stressed bones become thicker and stronger
Bone Degeneration
- Bone degenerates quickly
- up to 1/3 of bone mass can be lost in a few weeks of inactivity
Effects of Hormones and Nutrition on Bone
Normal bone growth and maintenance requires nutritional and hormonal factors
Minerals (what)
A dietary source of calcium and phosphate salts:
- Plus VERY SMALL amounts of magnesium , fluoride, iron, and manganese.
Vitamins
- Vitamin C is requited for collagen synthesis(1/3 of bone mass), and stimulates osteoblast differentiation.
- Vitamin A stimulates osteoblast activity
- Vitamins K and B12 help synthesize bone proteins.
Other Hormones
- Growth hormone and thyroxine stimulate bone growth
- Estrogens and androgens testosterm stimulate osteoblasts
- Calcitonin and Parathyroid hormone regulate calcium and phosphate levels
The Skeleton as Calcium Reserve
-Bone store calcium and other minerals
-Calcium is the most abundant mineral in the body
Functions of Calcium
Calcium ions are vital to:
- membranes
- neurons
- muscle cells, especially heart cells
Calcium Regulation
- Calcium ions in body fluids; must be closely regulated
- Homeostasis is maintained:
- by calcitonin and parathyroid hormone
- which control storage, absorption, and excretion
Calcitonin and Parathyroid Hormone Control
bones: Where calcium is stored
Digestive tract: where calcium is absorbed
Kidneys: where calcium is excreted
Parathyroid Hormone (PTH)
- Produced by parathyroid glands in neck
- INCREASES calcium ion levels by:
- stimulating osteoclasts
- increasing intestinal absorption of calcium
- decreases calcium excretion at kidneys
Calcitonin
Secreted by C cells (parafollicular cells) in thyroid
- Decreases calcium ion levels by:
- inhibiting osteoclast activity
- increasing calcium excretion at kidneys
What are the effects of aging on the skeletal system?
bones become thinner and weaker with age
- Osteopenia begins between ages 30 and 40
- Women lose 8% of bone mass per decade, men 3%
Osteoporosis - is a disease (more than 30% loss of calcium in your bones)
Osteopenia - is a sign
Effects of Bone Loss
The epiphyses, vertebrae, and jaws are most affect:
- resulting in fragile limbs
- reduction in height
- tooth loss
Osteoporosis
- Severe bone less
- Affects normal function
- Over age 45, occurs in:
- 29% of woman
- 18% of men
Hormones and Bone Loss
Estrogens and androgens help maintain bones mass
Bone loss in women accelerates after menopause
Cancer and Bone Loss
- Cancerous tissues release osteoclast-activating factor:
- that stimulates osteoclasts
- and produces severe osteoporosis
