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Skeletal System

Bio 209 Skeletal System

The human skeletal system is what percentage of total body weight? 15-20%
Functions of skeletal system support, protection, movement, mineral homeostasis (largly Calcium), and blood cell production
Location of blood cell (white, red, and platelets) production. Red bone marrow
3 main portions of a bone diaphysis (shaft), epiphysis (end), and metaphysis (middle)
Usual location of growth plate. metaphysis
Growth plate epiphyseal plate
what growth plate becomes when growth stops. epiphyseal line
At watch age do all human bones stop growing? around 25 years of age
Where does a bone usually elongate? Epiphyseal plate
What happens if growth plate is broken? Bone growth is disrupted and growth my cease.
What sits at the end of a bone (name?)? What is it's function? Articular cartilage sits on the epiphysis and reduces friction and acts as a shock absorber.
How long can the cartilage at the end of a bone last? 144 years
What is the fluid around joints and it's function? Synovial fluid lubricates
Why would someone take glucosamine? Humans lose the ability to make synovial fluid with age and take this as it is an ingredient in synovial fluid.
Describe what helps with growth in bone thickness. How? Periosteum (tough-not stretchy, dense, irregular, connective tissue) is a thin membrane on the outside of the bone that folds over itself to make bone thicker.
What are growing pains? The tough periosteum is getting stretched along a bone longwise because it is not keeping up with bone lengthening growth from epiphyseal plate.
What other tissue shares characteristics similar to the outer layer of bone? scar tissue
Hollow part of bone shaft and what happens here. Medullary cavity for yellow bone marrow (fat), -medulla=marrow
Thin membrane lining of hollow part of bone shaft. Endosteum
Another name for bone tissue osseous tissue
Surrounds the bone cells (give ingredients) Like other connective tissues, an extracellular matrix surrounds the cells. 25% H2O, 25% collagen, 50% crystallized mineral salts.
What is needed for bone calcification? Crystals of calcium hydroxyapatite (calcium phophate + calcium hydroxide-don't need to know) and ions (K, F, Mg, and S)
Bone calcification is initiated by what cells? osteoblasts
4 types of cells in bone tissue osteogenic cells, osteoblasts, osteocytes, and osteoclasts are present in osseous tissue
Dividing cells (Where are they found? What do they become? Osteogenic (-genic=producing) cells are the only bones that undergo cell division. They sit in the inner periosteum, in the endosteum, and in Volkmann's canals. They become osteoblasts.
Build bone. (Become what/) Osteoblasts (-blasts=buds or sprouts, in any name it means the cell secretes extracellular matrix) build bone and become osteocytes.
Maintain bone. Osteocytes (-cytes=cell, in name means cell maintains the tissue) are mature bone cells ("maintains" the daily metabolism, such as the exchange of nutrients and wastes with the blood)
Break down bone. Made of what? osteoclasts (-clast=break, in name means cells break down extracellular matrix) are huge cells made of up to 50 monocytes (type of white blood cell). Found in endosteum. (Side of cell facing bone) releases (lysosomal enzymes and)acids .
Osteoparosis could be from what activity of bone cells? Overexageration of osteoclasts and not enough oseoblasts.
What activity builds bone? Weight baring exercise (increased deposition of mineral salts and production of collagen fibers by osteoblasts). Without mechanical stress, resorption occurs more quickly than formation.
What supplements help build bone? Calcium WITH Vitamin D, Vitamin A
Types of bone tissue. What determines whether bone is as one type or another? Compact and spongy bone tissue. Size and distribution of spaces.
Osseous tissue with few spaces. Function and structure. Compact bone tissue is for protection and support. Made up of parallel tree-trunk-like osteons.
Cannals in compact bone. Volkmann's canals run transverse and contain blood vessels and nerves from the periosteum. The canals running longitudinally are haversian canals. They sit in the middle of each osteon.
Osseous tissue with more spaces. Location. Spongy bone tissue (w/in compact bone) makes up most of short, flat, irregular bones (clavicle, ribs, sternum, pelvis, scapula, scull...) and epiphysus of long bones.
Structure and function of spongy bone tissue. Trabeculae (=little beams) ("fingers") create spaces between them (helping make bones lighter) and can be filled with red bone marrow (produce blood cells). They have no osteons, but do have lacunae and canaliculi.
Location of osteocytes. Lacunae (=little lakes)
Radiating from sight of osteocytes. Canaliculi (=small channels) radiate in all directions from each lacuna and all these channels form an interconnected system for "communication of cells"(waste removal and O2 and nutrient provision)
Bone portion with the most nerve supply. Periosteum
Significance of old growth plate in nerve and blood supply. No nerve or blood supply goes through the epiphyseal line. There are separate supplies for either side of line.
process of bones growing ossification
when does bone formation begin? ossification begins at 6wks of embryonic development.
2 methods of bone formation Intramembranous ossification forms only the skull and mandible. Endochondral ossification (bone replacing cartilage) is the method used by all other bones of the body. Cartilage remains as epiphyseal plate until adulthood.
Age that growth plate becomes a "line." The Epiphyseal plate become the Epiphyseal line between 18 and 21 years, females generally earlier than males (more estrogen).
4 Zones of the growth plate/_______ 1)Resting Cartilage Zone (used as an anchor. No bone growth taking place) 2)Proliferating C.Z. (division of cells. Looks like stack of coins) 3)Hypertrophic C.Z. (columns of mature bone cells) 4)Calcified C.Z. aka New Diaphysis (a few cells thick)
Width growth of bone called what? Describe. Appositional Growth- periosteum folds over blood vessels and nerves ( now in haversian canal of osteon) and itself to adjust bone thickness.
Cells involved in bone homeostasis. Osteoblasts calcify bone and osteoclasts resorp bone.
3 main factors affecting bone growth. Vitamins (D,A,C,K,B12), minerals (P,Ca), and hormones.
Vitamin that stimulates osteoblast activity. Vitamin A
"Gatekeeper" of calcium absorption. Vitamin D (aka calcitriol) promotes absorption of calcium from foods in the gastrointestinal tract into the blood.
2 vitamins needed in synthesis of bone proteins Vitamins K and B12
Vitamin need for collagen synthesis. Vitamin C
Main bone protein collagen
Minerals needed for bone growth and remodeling and their relationship. What disrupts this? Phosphorus and Calcium have an inverse blood level relationship in adults. Soda containing phosphoric acid lowers calcium levels.
Hyperpetuitary and hypopetuitary Giantism and dwarfism.
Sits in sella turcica. petuitary gland.
Excretes hGH The Anteriorpetuitary excretes human growth hormone.
Role of hGH in bone growth. hGH once secreted by the anterior petuitary travels to the liver and bone tissue which then secrete the hormones insulinlike growth factors (IGFs) which increase osteoblast activity.
Gland that releases hormone directly stimulating osteoblasts. NAME hormones and conditions. Thyroid releases T3 and T4. Hypothyroid people are slow, cold, have weak bones. Hyperthyroid people are hot, active, have good bone structure.
Role of sex hormones in bone growth. Responsible for increased osteoblast activity, teenage "growth spurts," shutting down of epiphyseal plate. As adult, sex h. slow resorption (apoptosis of osteoclasts) and promote new (by osteoblasts).
Types of bone breaks. Open (compound) fracture breaks skin versus closed (simple) fracture doesn't break the skin. A comminuted fracture the bone is in many pieces between the 2 main fragments. A stress fracture is a series of microscopic fissures seen in bone scan not x-ray
-minuted = crumble
Most common place of stress fractures. 25% in tibia bone
What do we need to know about bone repair? A fracture repair is stronger than the original bone because of a bony callus around the break.
Does bone or cartilage heal faster? Why? Bone heals faster than cartilage because it has a blood supply running through it.
When is bone a "buffer?" Bones help "buffer" blood Ca2+ levels, releasing using osteoclasts or absorping using osteoblasts = calcium homeostasis.
Bone is a reservoir for what? 99% of total body calcium
What cells get Ca2+ from the blood? What else is Ca2+ needed for? Nerve and muscle cells. Blood clotting. Enzyme cofactor.
Required blood plasma Ca2+ level. Or what happens? 9-11 mg/100mL. If high, heart may stop. If low, breathing may stop.
What cells may be malfunctioning if calcium blood level is on low side? High side? Low- osteoblasts overworking or osteoclasts underworking. High- osteoblasts underworking or osteoclasts overworking.
How is blood calcium level increased? Parathyroid hormone (PTH) increases number and activity of osteoclasts AND causes kidneys to decrease loss of Ca2+ in the urine(more in blood) AND kidneys make more calcitriol formed (V.D).
Active form of vitamin D calcitriol
How does body decrease blood calcium level? When Ca2+ level rises above normal, the thyroid gland secretes calcitonin (CT) which slows osteoclasts and stimulates osteoblasts to store Ca2+ in bone.
Age of peak bone density for females. 20 to 21 years of age (max calcium)
Rate of bone density reduction occuring after menopause. 2% reduction/year (loss of calcium)
What gives bones their tensile strength? Collagen
What happens with decreased rate of protein synthesis? What causes this decreased rate? Less collagen means less tensile strength means brittleness. Caused by diminished production of hGH.
Low bone mass Osteopenia (-penia=poverty). Reduced bone mass from reduced bone synthesis not keeping up with bone resorption. Includes many conditions.
Systemic condition of porous bones. Osteoporosis (-por=pore + -osis=condition)(type of osteopenia) afflicts the entire skeletal system.
Deterioration of a joint. Usual 1st place. Osteoarthritis. ("bone joint inflimation") Saddle joint (thumb) from constant heavy use.
Problems associated with joint deterioration. 1)Joint space narrowing. 2)Bone hypertrophy, spurs, osteophytes. 3)Cartilage fragments. 4)Synovial fluid forced into bone ends (low pressure systems cause expansion of bubbles=pain)
Common name for deterioration of joint that gives wrong info. "Degenerative Disk (or Joint) Disease" NOT a disease.
Bone distruction due to infection, usually staff' bacteria. What does it look like? Osteomyelitis ("bone marrow inflimation"). Bone often turns black.
What are the roles of the thyroid vs parathyroid? Thyroid hormones T3 and T4 and calcitonin stimulate osteoblasts (if blood Ca too high). Parathyroid increases osteoclast activity and tell kidneys to flush out LESS Ca and make more calcitriol for Ca absorption in digestive tract (if blood Ca low).
Created by: 741879016



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