Skeletal System Flashcards
describe the following:
- diaphysis
- epiphysis
- metaphysis
- Articular cartilage
- periosteum
- medullary cavity
- endosteum
- physis
- shaft of the bone. tubular. compact bone
- ends of bone. formed of cancellous bone
- region between epiphysis and diaphysis. transitional region between cancellous and compact bone
- thin layer of hyaline cartilage covering part of the epiphysis where a bone forms an articulation
- tough connective tissue layer and associated blood supply that surrounds the bone surface. Osteoblasts are found in the deeper layer
- hollow space within the diaphysis; contains yellow bone marrow in adults
- highly vascular membrane that lines the medullary cavity
- layer of cartilage that separates the epiphysis and metaphysis. Responsible for longitudinal growth
Compact Bone Structure
- what are concentric lamellae?
- how are the concentric lamellae arranged?
- what are osteons and how are they arranged?
- what are the spaces between concentric lamellae called and what do they contain?
- what are canaliculi filled with?
- how do neighbouring osteocytes communicate?
- circularised plates of mineralised ECM of increasing diameter
- they are arranged around a central canal (network of nerves and vessels)
- the functional unit of compact bone; formed of concentric lamellae. Arranged in parallel to the long axis of the bone
- lacunae. Contain osteocytes
- ECF and the processes of osteocytes
- via gap junctions
Cancellous Bone Structure
- how does cancellous bone differ from compact bone?
- where is cancellous bone found?
- what does cancellous bone consist of?
- what are the spaces filled with?
- does not contain osteons
- interior of bones, protected by a covering of compact bone. e.g. interior of short, flat, irregular bones and the core of epiphyses of long bones
- lamellae, arranged in an irregular pattern of thin struts called trabeculae
- bone marrow
- what does bone ECM consist of?
- what does ground substance consist of? Why are these components important?
- Describe the function of the following cells:
a) osteoprogenitor cells
b) osteoblasts
c) osteocytes
d) osteoclasts
- collagen fibres, ground substsance, water and mineral salts
- glycoproteins and proteoglycans. They have a high ion binding capacity therefore are important in calcification
3a) mesenchymal derived bone stem cells. undergo cell division to form osteoblasts
3b) bone building cells. Secrete collagen to build ECM and initiate calcification. As they become surrounded and thus trapped by ECM, they become osteocytes
3c) mature bone cells. Maintain bone metabolism
3d) derived from monocytes. Have a deeply ruffled border from which it releases lysosomal enzymes and HCl to digest bone
Name 6 functions of bone
- support
- protection of internal organs
- assistance in movement
- mineral homeostasis - phosphate and calcium
- haematopoeisis
- triglyceride storage - yellow bone marrow
- from which embryological structures is the skeleton derived from?
- which structures give rise to the head?
- which structures give rise to the axial and appendicular skeletons?
- by which process does the skull develop?
- by which process do the limbs develop?
- which genes are involved in patterning the vertebrae? What are their gene products? What is their expression guided by?
- mesenchyme of the neural crest and mesoderm
- neural crest
- somites and lateral plate mesoderm
- intramembranous ossification
- endochondrial ossification
- Hox genes
- what is the basis of endochondrial ossification?
- describe the development of the cartilage model
- describe the growth of the cartilage model
- describe how the primary ossification centre develops
- describe the development of the medullary cavity
- describe the development of the secondary ossification centres
- replacement of cartilage with bone
- mesenchymal cells condense in the general shape of the future bone and develop into chondroblasts. Chondroblasts secrete ECM forming a hyaline cartilage model
- chondroblasts become surrounded by ECM, thus becoming chondrocytes. Continuous cell division causes the cartilage model to grow in length, accompanied by further secretion of ECM. Chondrocytes within calcifying ECM die; spaces left behind form lacunae
- nutrient artery penetrates calcifying cartilage model. Stimulates osteoprogenitor cells in perichondrium to differentiate into osteoblasts.
Periosteal capillaries grow into disintegrating calcified cartilage in moddle of model, inducing formation of primary ossification centre. Osteoblasts deposit bone ECM over remnants of calcified cartilage. Primary ossification spreads from centre outwards - osteoclasts begin to break down newly formed trabeculae, leaving a cavity
- branches of epiphyseal artery enter epiphyses and develop secondary ossification centres.
describe the stages of intramembranous ossification
- mesenchymal cells cluster together and differentiate into ostroprogenitor cells and osteoblasts, forming an ossification centre
- osteoblasts secrete EXM until they are surrounded by it
- osteocytes extend cytoplasmic processes into canaliculi
- mineral salts and calcium are deposited.
- where does growth of long bones occur from?
- Describe the following structures of the growth plate:
a) zone of resting cartilage
b) zone of proliferating cartilage
c) zone of hypertrophic cartilahe
d) zone of calcified cartilage - On which side of the growth plate is cartilage replaced with bone?
- epiphyseal growth plate
2a) nearest to epiphysis. acts to anchor the growth plate to the epiphysis
b) chondrocytes are arranged in stacks
c) large chondrocytes arranged in collumns
d) dead chondrocytes. Site of endochondrial ossification - diaphyseal side.
Describe and give examples of the following joints:
- fibrous
- cartilagenous
- synovial
- hinge
- pivot
- bicondylar
- condylar
- saddle
- pivot
- solid joint. Bones held together with connective tissue. E.g. sutures
- solid joint. Bones held together with cartilage. E.g. symphyses
- flexible joint. Bones involved are separated by articular cavity, and a layer of hyaline cartilage covers the articulating surfaces. Joint capsule consists of inner synovial membrane and outer fibrous membrane.
- movement (flexion and extension) around 1 axis (e.g. elbow)
- movement (rotation) around one axis (e.g. antaloaxial)
- movement mostly in one axis, with limited movement in a second (e.g. knee)
- movement in 2 axes at right angles to one another (e.g. wrist)
- movement in 2 axes at right angles to one another. Articulating surfaces are saddle shaped (e.g. thumb)
- movement in multiple axes (e.g. shoulder, hip)
Name and describe the 3 stages of fracture healing
- reactive phase - early inflammatory phase; fracture haematoma forms at the site of fracture; nearby bone cells die due to lack of blood flow. Phagocytes and osteoclasts remove dead and damaged tissue
- reparative phase - formation of fibrocartilaginous callus as fibroblasts grow into fracture haematoma and produce collagen. Cells from periosteum develop into chondroblasts which form fibrocartilage. Osteoprogenitor cells develop into osteoblasts which produce trabeculae and the fibrocartilage is converted to cancellous bone
- bone remodelling - remodelling of bony callous by osteoclasts
- describe the production of vitamin D3
- describe the negative feedback mechanism that prevents against vitamin D3 toxicity
- name 3 factors that regulate calcium homeostasis
- what occurs under levels of decreased calcium?
- what occurs under levels of increased calcium
- what do high levels of PTH stimulate?
- what do intermittent low levels of PTH stimulate?
- what is the major mediator of hypercalcemia in malignancy?
- what is calcitonin released by and how does it act?
- vitamin D3/cholecalciferol is produced from 7-dehydroxycholestrol in the skin by UV light
in the liver, it undergoes hydroxylation, forming 25 (OH) Vitamin D3
Further hydroxylation occurs in the kidney, forming 1,25 (OH) vit D3. This is metabolically active. - Further hydroxylation to produce 24,35 (OH) vit D3 or 1,24,25 (OH) vit D3. These prodices are not metabolically active.
- vitamin D3, parathyroid hormone and calcitonin
- PTH is secreted. This acts to increase renal Vit D3 hydroxylation; vit D3 acts to increase intestinal absorption and decrease renal excretion of Vit D3. PTH also stimulates osteoblasts, which stimulate osteoclasts to resorb bone.
- Decreased VitD3 production. Increased calcitonin secretion. Calcitonin inhibits osteoclasts.
- osteoclastic bone resorption (and vitD3 production)
- osteoblastic bone formation
- Parathyroid related protein. It is secreted by most malignant tumours and promotes hypercalcemia by activating the PTH receptor
- released by parafollicular cells of the thyroid in response to high plasma calcium. It acts to inhbit osteoclastic bone resorption.
- How to oestrogens act to maintain bone?
2. how do androgens act to maintain bone?
- they maintain bone mass by inhibiting resorption
2. they maintain bone mass by inhibiting resorption
- Name 5 causes of hypercalcemia
2. name 4 causes of hypocalcemia
- primary hyperparathyroidism; malignancy; hyperthyroidism; immobilisation; vitamin D toxicity
- renal failure; vitamin D deficiency; prematurity; secondary hyperparathyroidsm (a physiological response to hypocalcemia)
- what is osteomalacia and rickets?
- name 6 features
- name 6 causes
- what is osteoporosis?
- Name 6 causes
- name 5 treatments of osteoporosis
- softening of the bones
- diffuse bone pain; localised bone pain around hips; muscle weakness; elevated alkaline phosphatase levels; decreased mineralisation; bowing deformity of weight bearing long bones
- vitamin D deficiency; malabsorption; renal disease; lack of sunlight; anticonvulsants; inherited
- decreased bone density due to uncoupled bone remodelling. Deterioration of bone microarchitecture increases susceptibility to fracture
- lack of sex hormones. calcium deficiency. vitamin D deficiency. lack of weight bearing exercise; overuse of corticosteroids; thyroid problems
- calcium supplimentation; HRT; bisphosphonates; calcitonin; selective oestrogen receptor modulators