Anatomy > Bone > Flashcards

Bone Flashcards

Lecture 2 (61 cards)

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1
Q

What are the 4 types of tissue in the body?

A
  • Connective tissue (fat & other soft padding tissues, bone, tendon)
  • Epithelial tissue (lining of GI tract organs+ other hollow organs, skin surface [epidermis])
  • Muscle tissue (cardiac muscle, smooth muscle, skeletal muscle)
  • Nervous tissue (brain, spinal cord, nerves)
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2
Q

Connective tissue functions:

A
  • Provides a structural framework for the body
  • Transports fluids and dissolved materials
  • Stores lipids
  • Protects organs
  • Defends body from pathogens
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3
Q

What is bone?

A

Bone is a specialized type of connective tissue.
2 types: compact & spongy

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4
Q

Functions of bone:

A

Support: forms a supportive framework, giving shape and rigidity to the body.
* Locomotion: forms a system of levers that voluntary muscles attach to.
* Protection: protect soft and delicate organs e.g. the skull protects the brain.
* Haematopoiesis: Manufacturing of Red Blood Cells in red bone marrow,
situated in spongy tissue (medullary cavity) at ends of long bones.
* Mineral storage: bone is as a calcium reservoir to aid in maintaining blood Ca2+.
* Acid-base balance: absorbs or releases alkaline salts to aid in blood pH stability.
* Detoxification: store heavy metals and foreign elements to remove them.
* Sound transduction: bones are important in the mechanical aspect of hearing

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5
Q

What basic structures do long bones have?

A
  • Epiphysis = ends of long bones.
  • Diaphysis = shaft of long bones.
  • Metaphysis = between the other two.
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6
Q

Long bone eg + labels:

A

Eg: femur
Labels: articular cartilage, epiphyseal line, epiphysis, epiphyseal plate, spongy bone, metaphysis, medullary cavity, nutrient foramen, endosteum, periosteum, articular cartilage. (Tendon connects muscle to bone).

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7
Q

Articular cartilage

A

Articular surfaces of the epiphysis
are covered with articular
cartilage.

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8
Q

Periosteum

A

Tough fibrous membrane
covering the external
surface of bone.
* Its collagen fibres merge
with those of tendons
and ligaments.
* Well supplied with blood
vessels & nerve

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9
Q

What do most bones have?

A

A dense rigid outer shell = Compact bone
* a central cancellous zone of thin interconnecting narrow bone trabeculae
called spongy bone
-> major site of bone remodelling and
mineral homeostasis
* the spaces in the medullary cavity between the trabeculae of are occupied by
the haemopoietic bone marrow.

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10
Q

What is compact bone?

A

dense rigid outer shell around bone

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11
Q

What is spongy bone?

A

A central cancellous zone of thin interconnecting narrow bone trabeculae. This is a major site of bone remodelling & mineral homeostasis.

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12
Q

What occupies spaces in medullary cavity between trabeculae?

A

Haemopoietic bone marrow

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13
Q

Trabeculae

A

The number, thickness, orientation of
spongy bone trabeculae are dependant on
bone stress.
* e.g. weight bearing bones have many
others do not.

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14
Q

What is spongy bone?

A
  • Spongy bone makes up the interior of most bones
  • located deep to the compact bone
  • bony matrix consists of a 3D network of fine columns, which crosslink to form irregular trabeculae.
    » light, porous bone, strong against multidirectional lines of force
    » crucial in allowing the body to move.
    (if the only type of bone was compact, they would be too heavy to mobilise)
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15
Q

What is in the spaces between trebeculae?

A

Red marrow - for production of blood in immature animals.
* During age red marrow is mostly replaced by yellow,
or fatty marrow.

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16
Q

What is yellow bone marrow made of?

A
  • Yellow marrow= composed of adipose (fat) tissue.
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17
Q

What is an osteon?

A

basic structural unit of bone. Made bony
column layers (lamellae) containing mature bone cells
called osteocytes in lacunae.

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18
Q

What are lamellae?

A

Bony column layers. Surround neurovascular central canal which contain blood vessels, lymphatics & nerves.

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19
Q

What are osteocytes?

A

Mature bone cells in lacunae within the osteon.

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20
Q

What are osteogenic cells?

A

Stem cells of bone

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21
Q

What are Haversian systems composed of?

A

Collectively lamellae and central canals form Haversian
systems

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22
Q

What do perforating canals do?

A

Perforating canals run at right angles to the central
canals & link them up

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23
Q

What are canaliculi?

A

Fine canals between lacunae

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24
Q

What is contained within the central canal?

A

Blood vessels, lymphatics & nerves

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25
What are bones?
Bones are solid network of: a) Living cells b) Collagenous extracellular matrix (type I collagen) (called Osteoid). Bones are composed of 4 cell types: osteogenic cells, osteoblasts, osteocytes & osteoclasts.
26
What are osteogenic cells (stem cells)?
Osteogenic cells are undifferentiated & develop into osteoblasts. Located in periosteum and endosteum
27
How are osteocytes formed?
When osteoblasts get trapped within the calcified matrix, their structure & function changes, & they become osteocytes.
28
How do osteoclasts develop?
Osteoclasts develop from monocytes & macrophages & differ in appearance from other bone cells.
29
What are + functions of osteoblasts:
* bone forming cells -they are immature bone cells * synthesize uncalcified/unmineralized extracellular matrix called osteoid (by making alkaline phosphate), this will later become calcified/mineralized
30
What are + functions of osteocytes:
They are inactive osteoblasts in formed bone, with numerous cytoplasmic processes. Are smaller than osteoblasts, provide bone nutrition. Release calcium for purpose of homeostasis in whole body. * Activity is controlled by plasma calcium levels, parathyroid & calcitonin. * Osteoblasts & osteocytes respond to mechanical stress. * They maintain bone tissue * as the osteoid mineralizes, the osteoblasts become entombed between lamellae in lacunae where they mature into osteocytes. * monitor the minerals and proteins to regulate bone mass
31
What are + functions of osteogenic cells:
* maintain bone tissue * as the osteoid mineralizes, the osteoblasts become entombed between lamellae in lacunae where they mature into osteocytes. * monitor the minerals and proteins to regulate bone mass
32
What are + functions of osteoclasts:
* They are large phagocytic cells which contain many mitochondria * Important for constant bone turnover & restructuring. * Located in Howship’s lacunae. * Contain many lysosomes ->break down bone matrix * Parathyroid hormone simulates. - Calcitonin inhibits They develop from monocytes & macrophages * dissolve and break down old or damaged bone cells
33
What is osteoid?
Uncalcified/unmineralized extracellular matrix synthesised by osteoblasts. Will later become calcified/mineralized.
34
How do osteoblasts become osteocytes?
As the osteoid mineralizes, the osteoblasts become entombed between lamellae in lacunae where they mature into osteocytes.
35
Where are osteogenic cells located?
In the periosteum and endosteum (inner lining of bone)
36
What do osteogenic cells form?
osteoblasts and osteocytes
37
What do osteoclasts develop from?
Monocytes & macrophages
38
What do osteocytes provide and for what purpose do they provide it?
Provide bone nutrition - they release calcium for purpose of homeostasis in the whole body.
39
What is osteocyte activity controlled by?
Activity is controlled by plasma calcium levels, parathyroid & calcitonin.
40
What do osteoblasts & osteocytes respond to?
Mechanical stress.
41
What are osteoclasts NB for?
Important for constant bone turnover & restructuring.
42
Where are osteoclasts found?
* Located in Howship’s lacunae.
43
What do lysosomes do?
Break down bone matrix
44
What stimulates & inhibits osteoclasts?
Parathyroid hormone simulates. Calcitonin inhibits
45
What is ossification + when does it occur?
process of bone formation occurs via one of the two mechanism during fetal development
46
List the mechanisms of ossification + Eg:
Intramembranous ossification. Eg: Flat bones (e.g. Skull, Clavicle, Mandible and Endochondral ossification. Eg Long bones (e.g. Femur, Tibia, Humerus, Radius).
47
What is Intramembranous ossification?
: replacement of connective tissue sheets with bone tissue. >> bone develops directly from sheets of connective tissue (mesenchym).
48
What is Endochondral ossification?
replacement of a hyaline cartilage model with bone tissue. >> bone develops by replacing hyaline cartilage.
49
How do bones grow in length?
Activity in the epiphyseal plate (=stacks of chondrocytes) enables bones to grow in length. Epiphyseal plate = region of growth.
50
Endochondral Ossification Layers:
- bone in the epiphysis -proliferating chondrocytes (rapidly dividing cartilage cells form stacks that run parallel to the long axis of the bone) -calcification of carilage+ chondrocytes die -New bone formed
51
What is osteoporosis?
Osteoporosis: “A disease characterized by low bone mass and microarchitectural deterioration of bone tissue, leading to enhanced bone fragility and an increase in fracture risk.” 15% ( age 50s) and 70% (over 80)
52
Osteoporosis risk factors:
* menopause: low levels of estrogen * surgical removal of the ovaries * Smoking * Anorexia (Malnutrition) * Alcoholism * Vitamin D deficiency * Kidney diseases * Hyperthyroidism * Certain medication: antiseizure, proton pump inhibitors
53
Osteoporosis symptoms:
No symptoms until a bone is broken * typical fragility fractures (wrist, spine shoulder, hip) * acute and chronic pain, result in disability * impair mobility and may require surgery * (hip fracture, average mortality rate Europe 23.3 %) *curved back (compression fractures of back bones)
54
What is the average hip fracture mortality rate?
Hip fracture, average mortality rate Europe 23.3 %
55
How is osteoporosis diagnosed?
Dual-energy X-ray absorptiometry (DEXA). -Bone Mineral density (BMD) test results. BMD has 3 zones: green (normal), yellow (osteopenia) and red (osteoporosis). - T-score is the main result produced - it is the calculated value from the BMD within a standardised range representing a 30-year old patient of the same gender and ethnicity.
56
What is DEXA?
Dual-energy X-ray absorptiometry (DEXA).
57
What is BMD?
Bone Mineral density (BMD) test results. BMD has 3 zones: green (normal), yellow (osteopenia) and red (osteoporosis).
58
What is a T- score?
T-score is the main result produced - it is the calculated value from the BMD within a standardised range representing a 30-year old patient of the same gender and ethnicity.
59
Therapy for Osteoporosis:
Lifestyle: * Weight-bearing endurance exercise and/or exercises to strengthen muscles improve bone strength * Daily intake of calcium and vitamin D Pharmacological therapy: e.g. Bisphosphonates are a class of drugs that prevent the loss of bone density
60
What medication can be taken for osteoporosis?
Bisphosphonates - a class of drugs that prevent the loss of bone density
61
What is the endosteum?
Inner lining of bone - where osteogenic cells are located
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