Skeletal System Flashcards
What are the major functions of bones?
*support
*protection
*assistance in movement
*mineral storage and release
*blood cell protection
What makes up the skeletal system?
*bones
*associated connective tissues
- cartilage
-tendons
-ligaments
What does the cartilage do?
*protects joins
What do the tendons do?
*connects muscles to bone
What do ligaments do?
*connects bones to bones
What is the axial part of the ss?
*axial= all along the axis
- 80 bones
- houses vital parts of the body
What is the appendicular part of the ss?
*appendicular = appendage
*126 bones
*locomotion
What are the type of bones?
*sesamoid (lie within tendons)
*short bones
*flat bones
*long bones
*irregular bones
What is the structure of compact bone?
*dense and solid in appearance
*protecting and strength
*repeating circular units
-osteons
What is the structure of the cancellous (spongy) bone?
*characterised by open space partially filled with needle like structures = trabeculae
*strength without weight
What types of bone is in short, flat and irregular bones?
*inner portion = cancellous/ spongey bone
*outer portion = covered on the outside with compact bone
What types of bone make up the long bone?
*diaphysis (middle)
*outside - compact bone
*inner - spongy
*both ends of bone have epiphyses
= cancellous/ spongy in this region
*epiphyseal line = growth plate, bone will only extend in this region (new cells multiply here)
What is a part of the inorganic composition of bone matrix?
*inorganic salts
*hydroxyapatite
*chemical crystals of calcium and phosphate
*compression strength
What is a part of the organic composition of bone matrix?
*organic matrix
*composite of collagen (rope like) fibres and proteoglycans
*flexible strength
What is bone marrow like? + what are the two types of marrow?
*specialised soft like diffuse connective tissue
*red marrow
*yellow marrow
Where is red marrow found + what it produces?
*found in all bones in an infants or Childs body
*produce red blood cells
Where is yellow marrow found + what it produces?
*as an individual ages, red marrow is replaced by yellow marrow
*marrow cells become saturated with fat and are no longer active in blood cell production
What do progenitor cells develop into?
osteoblasts
What do osteoblasts do?
Bone-forming cells found in all bone surfaces
Ossifiction/osteogenesis
Secretes organic component – collagen
Produce vesicles: release Ca2+ and phosphate ions which contribute to hydroxyapatite formation
Osteoid
cannot divide again (no mitosis)
What do osteoblasts develop into?
osteocytes
What do osteocytes do?
Differentiated mature non-dividing osteoblasts
Trapped in lacuna and serve mainly as mechanosensors/ mineral homeostasis,
*cannot divide (no mitosis)
What do osteoclasts do?
Giant cells
Resorb bone through dissolving mineral and breaking down collagen
The “macrophages” of bone
(develop from blood cells called monocytes and macrophages)
What is entailed in bone remodelling?
*removal of existing bone by osteoclasts and the deposition of new bone by osteoblasts
*growth
*changes in bone shape
*the adjustment of bone to stress
*bone repair
*calcium ion regulation in the body fluids
What is entailed in the regulation of blood calcium levels?
*stores 98% of calcium reserves
*osteoblasts remove calcium from blood
*osteoclasts release calcium into blood
*calcium homeostasis:hormonal control
regulated by the parathyroid hormone(released when low lvl)
Vitamin D,(released when low lvl) Calcitonin (released when high lvl)
What does the PTH do?
Primary regulator
Stimulates osteoclasts to breakdown bone matrix
Increases kidney absorption of calcium from urine
What does Vit D do?
*increases the absorption of calcium from the small intestine
*increases blood calcium levels
What does Calcitonin do?
*hormone produced in the thyroid gland
*stimulates bone deposition by osteoblasts
*inhibits osteoclast activity
*decreases blood calcium levels
What happens to the structure of aging skeleton?
*Decreased collagen makes bones more brittle
*Cancellous bone lost first
*Decrease in no of trabeculae
*Followed by compact (lesser)
*Incomplete remodelling
