Skeletal system Flashcards
Major functions of the skeletal systems;
- support
- protection
- assistance in movement (muscles, power, tendons connect)
- mineral storage and release (blood/boje Calsium and Phosphorous levels maintained)
- blood cell production (red marrow present in certain use haematopoesis to produce RBCs, white cells, platelets)
Axial
Axial = along the axis
~80 Bones
Essentially houses the vital parts of the body
Appendicular
Appendicular = appendage
~126 Bones
- locomotion
Cartilage – protects joints,
Tendons – connects muscles to bone
Ligaments – connects bones to bones
The skeletal system
Bones
Associated connective tissues; include cartilage, tendons and ligaments
List the types of bones;
Sesamoid ( lie within tendons)
Short bones
Flat bones
Long bones
Irregular bones
Functions of Bones
support and articulation
Structure of different bones
Vary in proportions of:
Compact bone
dense and solid in appearance
Protection and strength
Repeating circular units
osteons
Cancellous (spongy) bone
characterized by open space partially filled with needle-like structures = trabeculae
Strength without weight
Short, flat, and irregular bones»_space;
Inner portion = is cancellous /spongy bone
Outer portion = covered on the outside with compact bone
Anatomy of a long bone
Diaphysis
Hollow
outside compact bone
Inner - spongy
Support without weight
Epiphyses (plural)
Both ends
Cancellous / spongy
Composition of bone matrix
Inorganic salts; Hydroxyapatite :
chemical crystals of Calcium and Phosphate
Compression strength
Organic matrix; Composite of collagen (rope-like) fibres and proteoglycans
Flexible strength
How many cells in a matrix of bones?
relatively small number
What is the bone marrow?
Specialized type of soft, diffuse connective tissue; called myeloid tissue
Bone marrow - haematopoiesis
Site for the production of blood cells
Medullary cavities of Long bone and in spaces of spongy bone= name two types of bone marrow
1) Red marrow
2) Yellow marrow
1) Red marrow
Found in virtually all bones in an infant’s or child’s body
Produce red blood cells
2) Yellow marrow
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Marrow cells become saturated with fat and are no longer active in blood cell production
3 major Major bone cells:
- Progenitor cells
- Osteoblasts
- Osteocytes
- Progenitor cells
differentiate into a specific cell type
- Osteoblasts (giant cells)
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
- Osteocytes
Differentiated mature non-dividing osteoblasts
Trapped in lacuna and serve mainly as
mechanosensors/ mineral homeostasis
- Osteocytes - functions and roles
Resorb bone through dissolving mineral and breaking down collagen
The “macrophages” of bone
(develop from blood cells called monocytes and macrophages)
Explain the process of bone remodelling
Removal of existing bone by osteoclasts and the deposition of new bone by osteoblasts
What are the results of bone remodelling?
growth
changes in bone shape
the adjustment of bone to stress
bone repair
calcium ion regulation in the body fluids
How is calcium levels maintained?
[ Skeletal system is a storehouse for 98% of body calcium ]
Calcium moves into and out of blood
Bone formation: osteoblasts remove calcium from blood
Bone breakdown: osteoclasts release calcium into blood
Calcium homeostasis : hormonal control
What happens to vit D, Calciyomnin, parathyroid hormone LEVELS?
Parathyroid hormone (PTH) (increase blood levels)
Vitamin D (increase blood levels)
Calcitonin ( decrease blood levels)
Parathyroid hormone (PTH)
Primary regulator
Stimulates osteoclasts to breakdown bone matrix
Increases kidney absorption of calcium from urine
= Increases blood calcium levels
Vitamin D
Increases calcium absorption from the small intestine
= Increases blood calcium levels
Calcitonin
Hormone produced in the thyroid gland
Stimulates bone deposition by osteoblasts
Inhibits osteoclast activity
decreases blood calcium levels
What is the affect of aging skeletol?
Decreased collagen makes bones more brittle
Cancellous bone lost first
Decrease in no of trabeculae
Followed by compact (lesser)
Incomplete remodelling
Why is the decrease in bone growth slightly more in female?
Due to menopause
Loss of the protective effect of oestrogen
(males - reduction in bone mass with age)
