Skeletal System Flashcards
How many bones compose the adult skeleton?
206
Axial Skeleton
Skull
Vertebral Column
Rib Cage
Laryngeal skeleton
Bones along body centre
Appendicular System
Pelvic & shoulder girdle
Limbs (Arms,hands,legs,foot)
What are the skeletal system functions?(6)
Supporting soft tissue & providing sites for attachment of skeletal muscles
Enable movement & postural control, together w/skeletal muscle
Storage of Ca2+ and K+
Protecting internal tissue (rib cage)
Red bone marrow producing red blood cells
Yellow bone marrow stores triglycerides aka fat
Which are the types of bones?
Flat bones in skull and ribs
Long bones in arms and legs
Short bones in wrists,ankles
Irregular shape in vertebra
How are flat bones structured?
2 outer layers of fairly tough flat material connected by spongy tissue arranged orthogonally to the flat compact layer surfaces
Allows for better protection of soft tissue in the skull and rib cages
Long Bones functionality
Hollow which makes them much lighter than otherwise but tough enough to achieve their function
Core of the bone used for yellow or red bone marrow
Bones Composition
Minerals improve rigidity. Without bone bendy
like rubber
Collagen adds flexibility. Without bone too brittle, would fracture more easily under physical stress
Optimal balance 60%-40% rigidity and flexibility
Long Bone Structure
(proximal)Epiphysis»Metaphysis»Diaphysis»Metaphysis»(distal)Epiphysis
hollow core=medular cavity
Epiphysis made of spongy/trabecular bone,covered in articular cartilage.
Diaphysis made of compact/cortical bone
Arteries enter medular cavity through foramen holes, nutrient arteries
Shaft cross sectional structure (inner to outter layers)
Medullary cavity ( w/ yellow bone marrow)»_space; endosteum»_space; compact bone»_space; periosteum
Thin layers of connective tissue: endosteum,inner,it can be reabsorbed if malnourished, & periosteum,outer, is continuous w ligaments/tendons connecting to muscles.
Blood vessels pass from periosteum to the bone
Blood Tissue Cells/Histology
Osteogenic cell (mitosis able), stem cell, in periosteum & endosteum
Osteoblasts,build bone matrix (collagen>ossification)
Osteocytes, maintain bone tissue
Osteoclasts reabsorve bone using enzymes,multinuclear from fused osteocytes.
Bone Growth: Where in the bone?
In Epiphysis
Proliferation zone of cartilage in epiphyseal plate.
Older cartilage is ossified forming new bone.
New cartilage produced in proliferation zone increases bone length.
Bone Growth : How is it controlled?
Stimulated by sex hormones in children to young adults.
Epiphyseal plate degenerates after growth spurt in adolescence - bone growth stops
Once fully grown bone continues to remodel
Foetal Growth
Bones in foetus formed from cartilage.
Ossification begins w/ accumulation of minerals as Calcium deposits.
Osteoblasts then continue to calcify cartilage cells
As child grows osteocytes replace osteoblasts
How often do bones remodel?
3 years, constantly under mechanical stress so they wear out
Mechanical Stress Stimulus on bones?
Positive!
Exercise increases bone strength
Inactivity decreases it & can lead to osteoporosis, where bones become brittle and fragile
Maintenance & remodelling:
Role of Calcium and Potassium?
Bone matrix formation.
WITHOUT IT?
soft,bendy bone
Maintenance & remodelling:
Role of Vitamin C?
bone matrix development, collagen synthesis
If concentration drops certain level > repair inhibition
WITHOUT IT?
Retarded growth & repair
Maintenance & remodelling:
Role of Magnesium & Vitamin A?
Required osteoblasts activity
WITHOUT IT?
bone poorly developed, bone stunting
Maintenance & remodelling:
Role of Vitamin D?
Positive effect Calcium absorption from gut.
Poor concentration indirectly leads to retarted growth & soft bones.
WITHOUT IT?
children suffer from rickets - defective calcification, bone fracture
Adults suffer osteomalacia - bone softening
Lack of ……. leads to retarde bone growth
Vitamin C
Osteoblasts activity is affected by lack of …….
Magnesium and Vitamin A
How is pre-puberty hormonal control maintained?
Human Growth Hormone from Anterior Pituitary Gland
Insulin Like Growth Hormone from bone and liver
Hormonal Control Disfunctions
Oversecretion»_space; gigantism
Undersecretary» dwarfism
Describe bone repair process ( 4 steps )
- Hematoma(blood clot) forms, area swells up
- collagen fibres connect pieces of bone inside internal callus. (w/ new blood vessels growing to increase blood supply locally)
- osteoblasts form the Bony callus, made of spongy bone. Hematoma is by now reabsorbed
- New compact bone is formed, spongy bone is reabsorbed & new medullary cavity is created
Red Marrow (function & where?)
Haematopoiesis: all blood cells formation except lymphocytes
Infants, nearly all bone marrow is red.
In medular cavity & spongy parts of long bones & in flat,short and irregular bones.
Adults, medular cavity of long bones contains now yellow bone marrow
Yellow Marrow (function & where?)
Fat Storage
In Medullary cavities long bones!
Can turn into red marrow in cases of extreme blood loss.
Abnormal Calcium concentration levels lead to ………. .
Ca2+»_space;> ; (HIGH) non responsiveness of nerves, abnormal calcium deposits
Ca2+ «
Calcium Regulation:
How body responds to low Ca2+?
Increase firing at parathyroid gland of PTH
- Increases no. & activity osteoclasts
- Decrease Calcium loss in urine
- Increase Calcitrol ( related to Vitamin D) in kidney>bigger calcium absorption from gut
> > > > > Levels of Calcium back to normal
(PTH -parathyroid hormone)
SKULL ANATOMY
Protect brain & provide attachment for facial & jaw muscles
Foraging enable blood vessels to enter bone core & build entry/exit for nerves
Babies sutures are moveable & meet at the fontanells. Allows frontal & parietal bones to move closer together.
In childbirth this allows skull to be slightly compressed without risk of fracture.
SPINAL COLUMN ANATOMY
Protects spinal cord
Support of body weight, posture & allows articulation
Curvature helps absorb shock & vibrations caused by walking
Intervertebral foramina provide space for relative movements between neighbouring vertebra & entry/exit points for peripheral nerves
RIB CAGE ANATOMY
Protects inner organs - heart & lungs, serve as attachments points for intercostal muscles that allow us to breathe
LIMBS ANATOMY
Hands & feet are mainly irregular bones
Legs & arms long bones
PECTORAL GIRDLE ANATOMY
*structural support for shoulder joints
PELVIC GIRDLE ANATOMY
- protection of reproductive & renal systems
- structural support for leg joints
- hips wider in females to support pregnancy & childbirth
Types of Joints?(3)
Fibrous joints - skull sutures, between fibula and tibia, nails or teeth
Cartilaginous joints - ends of long bones, moveable, in intervertebral disks
Synovial joints -highly mobile, joint cavity holds bones within a fibrous capsule, in shoulders,knees,..
