Chapter 7 Flashcards
What is the study of bone?
Osteology
What is the skeletal system made up of?
Bones, cartilages, and ligaments
What are ligaments?
Connective tissues that attach bone to bone
What are tendons?
Connective tissues that attach muscle to bone
What are the functions of the skeleton?
Support, protection, movement, electrolyte balance, acid-base balance, and blood formation
More abt the support function?
Limb bones and vertebrae support the body, jaw bones support teeth, some bones support viscera, etc.
More abt the protection function?
The skeleton protects the brain, spinal cord, heart, lungs, and more
More abt the movement function?
Skeletal system helps w limb movements, breathing, and more
More abt electrolyte balance function?
Skeletal system balances calcium and phosphate levels
More abt the acid-base balance function?
Buffers blood against large pH changes by altering phosphate and carbonate salt levels
More abt the blood formation function?
Red bone marrow is the chief producer of blood cells
What is bone made of?
AKA osseous tissue, made of connective tissue with the matrix hardened by calcium phosphate and other minerals
What is mineralization or calcification?
The hardening process of bone
What are individual bones made of?
Bone tissue, bone marrow, cartilage, adipose tissue, nervous tissue, and fibrous connective tissue
What are flat bones like?
Thin, curved plates that protect soft organs
What are long bones like?
Longer than wide, rigid levers acted upon by muscles and crucial for movement
What are short bones like?
Approximately equal in length and width, glide across one another in multiple directions
What are irregular bones like?
Elaborate shapes that don’t fit into the other categories
What is compact bone?
The dense outer shell/cortex of bone
What is spongy bone?
Loosely organized bone bound in the center of ends and shafts of long bones, and the middle of nearly all others.
What are the features of long bones?
Epiphyses and diaphysis, articular cartilage, epiphyseal line, compact and spongy bone, marrow cavity, periosteum, and endosteum
What is the diaphysis?
The shaft of a long bone, contains medullary cavity which has bone marrow and yellow marrow
What are epiphyses?
Enlarged ends of a long bone. Strengthen joint and anchor ligaments and tendons
What is articular cartilage?
A layer of hyaline cartilage that covers the joint surface, allowing it to move more freely
What is the epiphyseal plate?
AKA growth plate, an area of hyaline cartilage separating epiphyses and diaphyses of children’s bones. Enables length growth
What is the epiphyseal line?
In adults, marks where the growth plate used to be
What is the periosteum?
External sheath covering most of the bone. Has an outer fibrous layer of collagen and an inner osteogenic layer of bone-forming cells
What is the endosteum?
A thin layer of reticular connective tissue lining marrow cavity. Has osteoclasts and osteoblasts
What is the nutrient foramina?
Minute holes through which blood vessels and nerves enter the bone
Structure of flat bone?
Sandwich-like. 2 layers of compact bone enclosing a layer of spongy bone. Both surfaces covered w/ periosteum.
What is diploe?
The middle layer of flat bones. Spongy, absorbs shock. Marrow spaces are lined w/ endosteum. Has trabeculae - thin plate
What are osteogenic cells?
Stem cells found in endosteum and inner layer of periosteum. Multiply continuously and give rise to most other bone cell types
What are osteoblasts?
Bone-forming cells. Form single layer of cells under endosteum and periosteum. Nonmitotic.
What do osteoblasts do?
Synthesize soft organic matter of matrix which then hardens by mineral deposition. Stress stimulates osteogenic cells to multiple rapidly and increase the number of osteoblasts which reinforce bone
What are osteocytes?
Former osteoblasts that have become trapped in the matrix they deposited.
What are lacunae?
Tiny cavities where osteocytes reside
What are canaliculi?
Little channels that connect lacunae
What are cytoplasmic processes of osteocytes?
They reach into canaliculi and contact processes of neighboring cells.
What do osteocytes do?
Some reabsorb bone matrix, some deposit it. They act as strain sensors, producing biochemical signals that regulate bone remodeling
What are osteoclasts?
Bone-dissolving cells found on bone surface. Develop from the bone marrow stem cells that give rise to blood cells.
What do osteoclasts do?
Resorption - dissolving bone and returning minerals to the bloodstream
Osteoclasts structure?
Very large cells formed from fusion of several stem cells, w/ multiple nuclei in each cell. Ruffled border faces bone
What is the bone matrix?
1/3 organic and 2/3 inorganic matter. Organic matter is fibers and proteins synthesized by osteoblasts, and inorganic matter is mostly hydroxyapatite, some calcium carbonate, and small amounts of other minerals
Bone is a composite material, made up of what?
A ceramic (hydroxyapatite) and a polymer (collagen). Ceramic lets bone support body weight, polymer gives flexibility
What are osteons?
A system. A round portion of a compact bone
What is a central canal?
Large “hole” in the middle of an osteon
What are concentric lamellae?
Rings surrounding the central canal
What are perforating canals?
Horizontal passages that connect to central canals
Where are interstitial lamellae?
Filling irregular regions between osteons
Where are circumferential lamellae?
The outer region of dense bone (not really in the rings)
What are lacunae?
Dark spots in rings around the central canal of an osteon
What are spicules?
Slivers of bone in spongy bone
What are trabeculae?
Thin plates of bone in spongy bone
What fills the space of spongy bone?
Red bone marrow
Does spongy bone have central canals?
No
What is red bone marrow?
Bone marrow which produces blood
What is yellow bone marrow?
Fatty marrow only found in long bones. Children don’t have any. Doesn’t produce blood but can turn back into red marrow
What is the formation of bone called?
Ossification or osteogenesis
What is intramembranous ossification?
Process of developing flat bones as a fetus, later thickens and remodels adult long bones. Makes skull and clavicle bones!
What is endochondral ossification?
Process of bone developing from a pre-existing cartilage model. Most bones made this way
What is bone elongation?
When cartilage on the epiphyseal plate transitions to bone
What is interstitial growth?
Bones increase in length
When all cartilage in a bone has been turned into bone, what happens?
The epiphyses close and the epiphyseal line marks where the plate used to be
What are the 2 types of dwarfism?
Achondroplastic - bones stop growing
Pituitary - lack of growth hormone
What is appositional growth?
Growth at the bone surface, bones become wider
How much bone remodeling occurs each year?
About 10% of your skeleton is remodeled a year
Are mature bones still active or no? What do they do?
Yes, they are still metabolically active, maintaining their remodeling and exchanging minerals w tissue fluid
What is mineral deposition?
Process in which calcium, phosphate, and other ions are taken from blood and deposited in bone
What is mineral resorption?
Process of dissolving bone and releasing minerals into the blood. Performed by osteoclasts
What is abnormal calcification?
Formation of a calcified mass in an otherwise soft organ
What does phosphate do?
Besides being a part of bone structure, it is a component of DNA, RNA, ATP, phospholipids, and pH buffers
What does calcium do?
Besides bone structure, it’s used in neuron communication, muscle contraction, blood clotting, and exocytosis
What regulates calcium homeostasis?
Calcitriol, calcitonin, and parathyroid hormone
What is calcitriol?
Most active form of vitamin D, produced by skin, liver, and kidneys
How is calcitriol produced?
Keratinocytes convert a steroid into choleocalciferol using UV energy, and then a hydroxyl group is added, then it goes through the kidneys to become calcitriol
What does calcitriol do?
Raise blood calcium level
Why is calcitriol important?
It makes bones strong and solid, a lack of it means soft bones
What is calcitonin?
A hormone secreted by the thyroid gland when blood calcium levels are too high
What does calcitonin do?
Lowers blood calcium concentration by inhibiting osteoclasts and stimulating osteoblasts
Who is calcitonin most vital in?
Children
What does parathyroid hormone do?
When calcium levels are low, it raises blood calcium in 4 ways
How does PTH raise calcium levels?
Stimulates osteoblasts to secrete RANKL, which increases osteoclast population.
Promotes calcium reabsorption by kidneys.
Promotes calcitriol synthesis in kidneys, enhancing calcium-raising effect.
Inhibits collagen synthesis, which inhibits bone deposition
What is hypocalcemia?
Calcium deficiency in blood
What is hypercalcemia?
Excessive calcium levels
Effects of hypocalcemia?
Overly excitable nervous system and tetany (muscle spasms)
Effects of hypercalcemia?
Nerve and muscles are less excitable, can cause weakness, sluggishness, cardiac arrest
How much phosphorous does an average adult have?
500-800g, with 85-90% in the bones
What affects bone tissue?
Calcium, phosphorous, and 20+ hormones, vitamins, and growth factors
When is bone growth most rapid?
Puberty and adolescence, because of surges of growth hormone, estrogen, and testosterone occur
What is orthopedics?
Branch of medicine dealing w/ prevention and correction of bone, joint, and muscle injuries/disorders
What is a stress fracture?
A break caused by abnormal trauma to a bone (like a fall)
What is a pathological fracture?
A break in a bone weakened by disease (like bone cancer or osteoporosis)
How are fractures classified?
Direction of fracture line, break in the skin, and multiple pieces
What is a nondisplaced bone fracture?
The bone pieces remain in proper anatomical alignment
What is a displaced bone fracture?
At least one piece is shifted out of alignment with the other
What is a comminuted bone fracture?
A bone is broken into 3 or more pieces
What is a greenstick bone fracture?
A bone is incompletely broken on one side and bent on the opposite side
4 steps of fracture healing?
1 - Hematoma formation (converted to granulation tissue)
2 - Soft callus formation (granulation tissue turns into soft callus bc of collagen and fibrocartilage)
3 - Hard callus formation (osteoblasts make bony collar around fracture)
4 - Bone remodeling (small bone fragments are removed while spongy bone is deposited and then turned into compact bone)
What are the ways of treating a fracture?
Closed reduction, open reduction, cast, traction, and pins
What is closed reduction?
A procedure where bone fragments are manipulated into their normal positions without surgery
What is an open reduction?
Surgical exposure of the bone and use of plates, screws, or pins to realign fragments
When are tractions used often?
Children femur fractures
What is osteoporosis?
Most common bone disease, a severe loss of bone density
How does estrogen affect bones?
It maintains bone density in both sexes and inhibits resorption by osteoclasts. (When women get older and have less estrogen, their osteoclasts are no longer inhibited)
How can you slow down osteoporosis?
Prevention - exercise and eat foods w/ calcium from age 25-40
