W10 The Skeletal System Flashcards

Bones and Bone tissue

1
Q

What are the major functions of bones and bone tissue? (5)

A
  1. Support
    ▪ Provides a framework, and provides attachment points for muscle and tendons; ligaments connect bone to bone
  2. Protection
    ▪ Containment of valuable organs
  3. Assistance in movement
    ▪ Muscle provides the power; skeleton provides the movement; tendons connect
  4. Mineral storage and release
    ▪ Blood/bone Calcium and phosphorous levels maintained
  5. Blood cell production
    ▪ Red marrow present in certain bones use haematopoiesis to produce RBCs, white cells, platelets
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2
Q

Axial and Appendicular systems:
How many bones are in each?

A

Axial = along the axis
~80 Bones
Essentially houses the vital parts of the
body

Appendicular = appendage
~126 Bones
- locomotion

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3
Q

The Skeletal System:
What is included?

What does cartilage protect?
What do tendons connect?
What do ligaments connect?

A
  • Axial Bones and Appendicular bones
  • Associated connective tissues
  • Cartilage, tendons, and ligaments

Cartilage –protects joints,
Tendons –connects muscles to bone
Ligaments –connects bones to bones

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4
Q

What is the function of bones?
What are the types of bone? (5)

A

Function: Support and articulation

  • Sesamoid ( lie within tendons)
  • Short bones- wider than they are long (found in ankles and wrists)
  • Flat bones e.g. skull, ribs
  • Long bones- longer than they are wide
  • Irregular bones
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5
Q

What are the 2 structures of bones?

A

Compact bone
Cancellous (spongy) bone

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6
Q

What is compact bone? (5)
What does it consist of?
Where is it found?

A
  • Dense and solid in appearance
  • Protection and strength
  • Repeating circular units
  • Consists of Osteons
  • Found in long bones
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7
Q

What is Cancellous (spongy) bone/trabecular bone?

A
  • Characterised by open space partially filled with needle-like structures = trabeculae
  • Strength without weight (weighs way less than compact)
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8
Q

Short, flat, and irregular bones:
What are the inner and outer portions like?

A

Inner portion = cancellous /spongy bone
Outer portion = covered on the outside with compact bone

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9
Q

Anatomy of a long bone (need to know)

A
  • Diaphysis/Shaft
  • Hollow
  • Outside compact bone
  • Inner = spongy- support without weight
  • Epiphyses (plural)
  • Both ends
  • Cancellous / spongy
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10
Q

What is bone matrix composed of? (2)

A
  1. Inorganic salts
    Hydroxyapatite :
    - Chemical crystals of Calcium and Phosphate
    -Compression strength
  2. Organic matrix
    - Composite of collagen (rope-like) fibres and proteoglycans
    -Flexible strength

Bone- Relatively small number of bone cells in a matrix

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11
Q

What is Bone Marrow?
What is it the site of?

A
  • A specialised type of soft, diffuse connective tissue; called myeloid tissue
  • Site for the production of blood cells- Haematopoiesis
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12
Q

Where is bone marrow found?

A
  • Found in medullary cavities of long bones and in the spaces of spongy bone
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13
Q

What are the 2 types of bone marrow?
Where are they found?

A

Red marrow and Yellow marrow

Red
-Found in virtually all bones in an infant’s or child’s body
- Produce red blood cells

Yellow
- As an individual ages, red marrow is replaced by yellow marrow
- Marrow cells become saturated with fat and are no longer active in blood cell production

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14
Q

In which bones does haematopoiesis take place?

A

Cranium
Ribs
Skulls
Pelvis
Ends of long bones (epiphyses)

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15
Q

What are the major bone cells? (4)

A
  • Progenitor cells
  • Osteoblasts
  • Osteocytes
  • Osteoclasts
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16
Q

What are mature osteoblasts called?

A

Osteocytes

17
Q

What are osteoblasts?

A
  • Bone-forming cells found in all bone surfaces
  • Ossification/osteogenesis (lay down bone)
  • Secretes organic component –collagen
  • Produce vesicles: release Ca2+ and phosphate ions which contribute to hydroxyapatite formation
  • Osteoid
18
Q

What are osteocytes?

A
  • Differentiated mature non-dividing osteoblasts
  • Trapped in lacuna (calcified matrix) and serve mainly as mechanosensors/ mineral homeostasis
    *They sense what’s happening in bone
19
Q

What are osteoclasts?

A
  • Giant cells
  • Resorb bone through dissolving mineral and
    breaking down collagen
  • The “macrophages” of bone
  • (develop from blood cells called monocytes and macrophages)
    *They break down bone
20
Q

What happens during Bone Remodelling? (6)

A
  • Removal of existing bone by osteoclasts and the deposition of new bone by osteoblasts
  • Growth
  • Changes in bone shape
  • The adjustment of bone to stress
  • Bone repair
  • Calcium ion regulation in the body fluids
21
Q

How are calcium levels regulated?

A
  • Skeletal system: storehouse for about 98% of body calcium reserves
  • Calcium moves into and out of blood
  • Bone formation: osteoblasts remove calcium
    from blood (and lay it down in bone)
  • Bone breakdown: osteoclasts release calcium into blood
  • Calcium homeostasis : hormonal control
  • Parathyroid hormone (PTH)* Primary regulator
  • Stimulates osteoclasts to breakdown bone matrix
  • Increases kidney absorption of calcium from urine
  • Increases blood calcium levels
  • Vitamin D * Increases calcium absorption from the small intestine
  • Increases blood calcium levels
  • Calcitonin* Hormone produced in the thyroid gland
  • Stimulates bone deposition by osteoblasts
  • Inhibits osteoclast activity
  • decreases blood calcium levels
22
Q

What are the 3 hormones that are important in calcium homeostasis?

A
  1. Parathyroid hormone (PTH) (inc blood levels)
  2. Vitamin D (inc blood levels)
  3. Calcitonin (dec blood levels)
23
Q

How does Parathyroid (PTH) hormone help regulate calcium homeostasis?

A
  • Primary regulator
  • Stimulates osteoclasts to breakdown bone matrix
  • Increases kidney absorption of calcium from urine
  • Increases blood calcium levels
24
Q

How does Vitamin D help regulate calcium homeostasis?

A
  • Increases calcium absorption from the small intestine
  • Increases blood calcium levels
25
Q

How does Calcitonin help regulate calcium homeostasis?

A
  • Hormone produced in the thyroid gland
  • Stimulates bone deposition by osteoblasts
  • Inhibits osteoclast activity
  • Decreases blood calcium levels
26
Q

What changes occur to the skeleton during ageing?
What bone is lost first?
What decreases?

A
  • Decreased collagen makes bones more brittle
  • Cancellous bone lost first
  • Decrease in no of trabeculae
  • Followed by compact bone
  • Incomplete remodelling
27
Q

What is osteoporosis?

A
  • Bone resorption exceeds bone deposition.
  • First Line Therapy: oral bisphosphonates eg alendronic acid and risedronate sodium
  • Induce osteoclast apoptosis (death) and suppress bone resorption
28
Q

Bones in the wrist are categorised as what?

A

Short bones

29
Q

Long bones grow in length due to activity in the ____?

epiphyseal plate

perichondrium

periosteum

medullary cavity

A

epiphyseal plate

30
Q

Which of the following are capable of undergoing Mitosis?
-Osteoblasts
-Osteocytes
-Osteoclasts
-Progenitor cells

A

Progenitor cells

31
Q

Which of the following lay down bone?
-Osteoblasts
-Osteocytes
-Osteoclasts
-Progenitor cells

A

Osteoblasts

32
Q

The major bone cells produce in which order?

A

Progenitor- Osteoblast- Osteocyte