Skeletal system Flashcards
what are 6 functions of the skeleton
support, body movement, protection, storage of minerals, blood cell production, fat storage
what bone protects the brain
the cranium
what bone protects the spinal cord
vertebral column
where are haemopoietic stem cells found?
red bone marrow
what is the difference between bone marrow in babies and adults?
babies have only red bone marrow- yellow marrow is produced over time due to a decrease in erythropoietin
what minerals are stored in the bones
99% of body’s calcium, 85% of phosphate, 50% of magnesium
give an example of a hormone which regulates and maintains mineral levels in the bones
parathyroid hormone
what function has yellow marrow in the body?
can store fat- has adipose cells which can store triglycerides
what are the two divisions of the skeleton
axial skeleton and appendicular skeleton
describe the bone structure of the skull
8 cranial and 14 facial bones. cranial bones fuse after 12-18 months
describe the structure of the sternum
flat and dagger shaped, located in the mid chest
describe the structure of the ribs
thin, flat and curved. 24 bones in 12 pairs
write a note on the three categories that the ribs are divided into
true ribs- are the first seven bones and they go all around the chest diameter. False ribs are the next 3 pairs and these are not connected directly to the sternum (coastal cartilage). Last two are floating ribs- protect the kidneys and do not cover the whole chest
how many vertebrae are in the vertebral column
33
name the 5 categories of the vertebral column
cervical vertebrae, throracic, lumbar, sacrum, coccyx
what is the function of the cervical vertebrae
support the head and neck - flexible framework
what is the function of the throacic vertebrae
move with the ribs and form the rear anchor of the rib cage- larger than the cervical vertebrae and increase in size from top to bottom
what is the function of the lumbar vertebrae
support most of the body’s body weight, attach to many back muscles and are the largest vertebrae in the spinal column
what is the function of the sacrum
triangular bone located below the lumbar vertebrae- composed of 4-5 bones in a child which fuse in adulthood (age 26). forms the back of the pelvic girdle and is able to move with it.
how many bones are in the coccyx
3-5 bones fused together in adults
what are between the vertebrae
intervertebral discs (fibrous cartilage)
what is included in the term “upper extremities”?
the arm (humerus), forearm (radius and ulna) and the hand which has 27 bones- wrist (carpels), palm (metacarpals) and five fingers (phalanges)
what bones are included in the term “lower extremities”
thigh (femur), leg (fibula and tibia), kneecap (patella) and foot which has 26 bones including 7 tarsel bones, metatarsels and phalanges
what 4 bones make up the pectoral/shoulder girdle
two clavicles and two scapulae
What bones make up the pelvic/hip girdle?
2 coxal bones (made up of ilium, ischium, & pubis - fused in adults)
Where do the 2 coxal bones meet?
Either side of the sacrum, connected by the pubis symphysis
What are the 5 types of bones?
Long bone, short bone, flat bone, sesamoid bone, irregular bone
What is a long bone?
Longer than they are wide, act as lever, upper & lower extremities
What is a short bone?
Short, cube shaped, wrists and ankles
What are flat bones?
Broad surface - protection and connection to muscle - ribs, cranium, shoulder girdle
What is a sesamoid bone?
Small round bone embedded in tendon - reinforce and decrease stress - knee, thumb, big toe
What is an irregular bone?
Various shape & size - vertebrae, skull
What is the structure of a long bone?
A long shaft (diaphysis) & 2 bulky ends (epiphysis)
Outer consists of compact bone, inner consists of spongy bone(bone marrow), medullary cavity
What is bone matrix made of?
25% organic matrix (osteoid) (90% Type-I collagen & 10% proteins such as glycoprotein, osteocalcin, proteoglycans
50% inorganic material (salt) - Ca2+ supports & hardens
25% water
What is the composition of bone?
Connective tissue - widely separated living bone cells embedded in a matrix of collagen fibres, mineral salts (needle-shaped crystals) in a semisolid gel
What are the mineral crystal in bones made of?
Calcium phosphate and calcium carbonate
What is compact bone?
Highly organised, made of tubular units (osteons) containing osteocytes in lacunae arranged in concentric rings around the central canal, matrix between lacunae, tiny canals called canaliculi run through matrix and connect lacunae
What is spongy bone?
Higher surface area, irregular structure, less dense, softer, weaker and less stiff - ends of long bones, proximal to joints & interior of vertebrae - highly vascular, red bone marrow (site of hematopoiesis) - units called trabecula
What are lacunae?
Cavity where bone cells are found
What are lamellae?
Thin membranes
What are canaliculi?
Narrow canals connecting lacunae
What is an osteon?
Structural unit of a bone cell
What is a periosteum?
Outer fibrous layer
What are trabeculae?
Spongy, porous, soft tissue
What is the Haversian canal?
Location of nerves and capillaries
What are Volkmann’s canal?
Perpendicular to Haversian canal
What are the 5 bone cells?
Osteogenic cells, osteoblasts, osteocytes, osteoclasts, and bone-lining cells
What are osteogenic cells?
Respond to trauma (fractures), gives rise to osteoblasts and osteoclasts
What are osteoblasts?
Bone-forming cells - synthesise & secrete unmineralised ground substances - found in areas of the bone with high metabolism
What are osteocytes?
Mature bone cells from osteoblasts - maintain healthy bone tissue - enzyme secretion and control the release of calcium from bone to blood
What are osteoclasts?
Large cells that break down bone - important for growth, healing, & regeneration
What are bone-lining cells
Derived from osteoblasts, regulates the movement of calcium & phosphate in & out of the bone
How long does it take for the skeleton to replace itself?
7 years
Why is bone broken down and replaced?
Minerals transported to other parts of the body, in response to stress (weight-bearing exercise=stronger bones)
What are the 2 types of bone formation?
Intramembranous ossification (direct ossification of embryonic connective tissue) & Endochondral ossification (replacement of hyaline cartilage)
What are the stages of intramembranous bone formation?
- increased vascularity
- Proliferation of mesenchymal cells (give rise to osteogenic cells > osteoblasts)
- Osteoblasts lays down to osteoid (organic part of bone)
- Osteoblasts either retreat or become trapped as osteocytes in osteoid
- Osteoid calcifies (inorganic salts deposit as fine crystals in an orderly fashion in collagenous fibres) to form spicules of spongy bone. Spicules unite to form trabeculae.
- Periosteum & compact bone formed
What are the stages of endochondral ossification?
(most bones)
1. Hyaline cartilage model develops in foetus - replaced by bone development
2. cartilage breaks down in centre of diaphysis - now surrounded by periosteum
3. Osteoblasts invade & create a primary ossification centre - spongy bone first laid down
4. Compact bone laid down - osteoclasts create medullary cavity
5. At birth, secondary ossification centre forms at epiphysis - spongy bone
6. Band of cartilage remains between primary and secondary ossification sites (growth plates) - bones keep growing until plates ossify
Describe bone repair.
- Haematoma forms from blood from ruptured vessels within 6-8 hours
- Fibrocartilage fills the space in 2-3 weeks
- Bony callus forms - osteoblasts produce the trabeculae of spongy bone - joins bone after 3 months
- Osteoblasts remodel & osteoclast form new medullary cavity
