The Skeletal System Flashcards
*The skeletal system consists of:
- Bones
- Joints
- Cartilage
*Functions for the body:
- Support and shape
- Protection
- Movement
- Mineral reservoir
- Blood cell formation
Support and shape:
Supporting framework for body
Protection:
E.g. skull protects the brain,
Rib cage protects heart and lungs
Movement:
Bones and joints constitute levers. Muscles are anchored firmly to bones as muscles contract and shorten; they pull on bones, producing movement at a joint.
Mineral reservoir:
Bones store calcium, phosphorus and certain other minerals.
*Blood cell formation:
Vital process carried by red bone marrow
*As an infant gets older, what does red bone marrow turn into?
Yellow marrow, which is inactive fatty tissue
*Main adult red bone marrow sources:
Sternum Spinal Column Base of skull Upper arm And thigh
*We can’t survive without red bone marrow because?
It forms blood cells
*Types of bones:
Long bones (leg, arm) Short bones (wrist, ankle) Flat bones (ribs, skull) Irregular bones (face bones, ear bones, spine or vertebrae)
Structure of a long bone:
Diaphysis
- main shaft like portion
Composed of thick compact bone
*Structure of long bone:
Epiphyses
- both ends of a long bone
- Yellow marrow fills spaces of spongy bone in most adult epiphyse; but not in proximal epiphyses and femur. These contain red bone marrow
Structure of long bone:
Articulate cartilage
Thin layer of hyaline cartilage (glassy, translucent) that covers joint surfaces of epiphysis.
*Structure of long bones:
Periosteum
- dense white fibrous membrane that covers bone, except at joint surfaces
- bone forming cells called OSTEOBLASTS, compose inner layer of PERIOSTEUM
*Osteoblasts are essential for:
Bone cell survival and bone formation
*Structure of long bones:
Medullary (or bone marrow) cavity
- tube like hollow in diaphysis of long bone
- in adult it contains yellow marrow
Structure of long bone:
Endosteum
-membrane that lines medullary cavity of long bones
Structure of long bones:
Compact bone
- hard and dense
- makes up main shaft of the long bone and the outer layer of other bones
*Short, flat, irregular bones:
[Red bone marrow] fill spaces in spongy bone inside a few irregular and flat bone (e.g vertebrae)
The other irregular, short and flat bones contain [yellow bone marrow]
*Microscopic structure of bone:
- bone consists of living and non living intercellular substance
- intercellular material (called matrix of bone) is more abundant than bone cells and it contains fibres of collagen
*Bone differs from other connective tissue in that..
It is ridged, not soft and flexible; it is calcified (it has calcium in it)
*Human skeleton consists of 2 main divisions:
- Axial skeleton (74 bones)
2. Appendicular skeleton (126 bones)
*Axial skeleton:
Skull
28 irregular shaped bones form the skull Consists of 2 divisions: 1. Cranium (8 bones) 2. Face (14 bones) 3. Ear (6 bones)
*Spinal column (5):
(7) cervical vertebrae
(12) thoracic vertebrae
(5) lumbar vertebrae
(1) sacrum
(1) coccyx
*Sternum:
- breast bone: dagger shaped bone
- red marrow can be drawn up in a syringe by inserting needle through skin and bone; examined for abnormal or normal cells
*Ribs:
12 pairs of ribs
Skeletal differences in men and women:
Male skeleton generally larger and heavier
*Age changes:
- As bones mature, they lose calcium
- In most women, calcium loss from bone diseases develops after 40 y/o
- femur especially vulnerable
- if we live long enough, most of us will develop bone disease osteoporosis
- generalized decrease in organic matrix
- thinning of intervertebral disks
**Bone growth and resorption:
A
Growth in length by continual thickening of epiphyseal (articular) cartilage followed by ossification (replacement of cartilage by bone)
**Bone growth and resorption:
B
Growth in diameter- medullary cavity enlarged by osteoclasts destroying bone around it, while new bone is added around outside by osteoblasts (build)
**Bone growth and resorption:
C
Opposing processes of bone tissue formation and destruction (resorption) go on concurrently through life.
- (infancy to adolescence) bone formation exceeds resorption
- (young adulthood) resorption balance each other
- (after young adulthood) 35-40 bone resorption, than formed; become weaker and fracture easily
*Osteocytes:
Mature bone cells
**Factors that affect the development of bones include:
- Genetic factors: length thickness of a bones are inherited
- Nutrition: A balanced diet high in vitamin D and minerals such as calcium maintains a healthy bone development.
- Hormones: affect the growth and development of bones hormones are chemical/messengers, which are sent via the blood supply to the bones. They are responsible for informing the bones about when to stop growing etc.
*Cartilage:
- both resembles and differ from bone
- flexible of a firm plastic material
- cartilage has no blood vessels
Response to stress:
- walking, jogging, and other forms of exercise subject bones to stress
- they respond by laying down more collagen fiber, and mineral salts (e.g. calcium) in bone matrix
*Skeletal system:
Articulations (joints)
Articulations in the body or joints between bones.
Their purpose:
•holds bones bound to one another or spine
•Permit movement between them
**Hyoid bone:
- Only free floating bone in the body
- Helps with tongue movement
- Helps with swallowing
**Long bone:
Diagram
Left side:
proximal epiphysis (top)
Diaphysis (middle)
Right side: Endosteum Compact bone Medullary cavity Periosteum Artery Distal epiphysis (bottom)
Collagen:
A fibrous protein that gives strength and resilience to tissue and bone matrix
