Skeletal and Muscle Systems Part 1

Question 1

Purpose of the Skeletal System

Answer 1

• Forms the body
• Supports tissues
• Permits movement by providing points of attachment for muscles
• Site of blood cell formation
• Mineral storage (especially Calcium)
• Rigid connective tissue
• Constituents
• Cells
• Fibers
• Ground substance

Question 2

Bone is an Organ

Answer 2

• bone tissue (connective tissue classification)
• cartilage tissue (connective)
• fibrous connective tissue
• blood (connective)
• nerve tissue

Question 3

Bone Structure

Answer 3

A. Parts of a long bone
1. Epiphyses at both ends
covered with articular cartilage; articulates w/ bone
2. Diaphysis - shaft
3. Periosteum covering
4. Compact bone - strength and resists bending
5. Spongy bone - strength with weight reduction
6. Medullary cavity - red or yellow marrow

Question 4

Bone Structure

Answer 4

B. Microscopic structure

1. CORTICAL or Compact bone has osteons cemented together
2. Osteonic canals with blood vessels
3. Intracellular matrix of collagen & inorganic salts (Ca, Mg, K, Carbonate, Na)
4. Spongy cells nourished by diffusion from thin bony plate surfaces
5. Osteocytes
6. Osteoblasts
7. Osteoclasts

Question 5

Osteoblasts- Modeling bone cells

Answer 5

– Derived from mesenchymal cells
– Produce type I collagen
– Respond to parathyroid hormone
– Produce osteocalcin
– assist in calcification
– Synthesize osteoid
• Nonmineralized bone matrix

Question 6

Osteocytes

Answer 6

– A transformed osteoblast that is surrounded in osteoid as it hardens from deposited minerals
– i.e. - mature bone cells (calcified matrix surrounding osteoblasts)

Question 7

Osteoclast

Answer 7

• cells to break down the calcified matrix
• The major reabsorptive cell of the bone
• produce acids to solubilize salts
• Large, multinucleated cells
• digest organic matrix
– Contain lysosomes filled with hydrolytic enzymes

Question 8

Bone Matrix

Answer 8

• 35% organic and 65% inorganic
• Collagen fibers
• Calcium and phosphate minerals
• Proteoglycans
• Glycoproteins

Question 9

Nerve Supply Bone

Answer 9

• sparse
• periosteum
• afferent sensory
• sympathetic efferent
• dilation of bone
  
  • blood vessels

Question 10

Bone Blood Supply

Answer 10

• small bones single artery and vein
• chief is Principle Nutrient artery
• internal branches

Question 11

Bone Tissue:

Compact (Cortical) bone

Answer 11

– 85% of the skeleton
– Haversian system
• Haversian canal, lamellae, lucunae, osteocyte, and canaliculi

Question 12

Bone Tissue:

Spongy (cancellous) bone

Answer 12

– Lack haversian systems

– Trabeculae

Question 13

Bone Tissue:

Periosteum

Answer 13

• See textbook

Question 14

Homeostasis of Bone

Answer 14

Constant modeling and remodeling

3 - 5% bone calcium exchanged each year

Question 15

Bone Remodeling

Answer 15

• Bone-remodeling units
• Repairs microscopic injuries and maintains bone integrity
• Phases
– Activation of the remodeling cycle
– Reabsorption
– Formation of new bone

Question 16

Factors Affecting Bone Growth (Formation)

Answer 16

• Calcium, Phosphorus
• Parathyroid Hormone
• Vitamin D
• Calcitonin
• Sex Hormones
• Growth Hormone
• Weight bearing
• Glucocorticoids
• Vitamins A and C

Question 17

Calcium, Phosphorus

Answer 17

• plasma and interstitial fluid
  -osteoblasts
• calcium salts precipitate on collagen fibers
  -hydroxyapatite crystals
  - crystalline structure of
  bone mineralization
• GI absorb
  -Vit D and PTH
  -PTH and calcitonin
• phosphorous absorb with Ca

Question 18

Parathyroid Hormone

Answer 18

 GI absorb Ca
 promotes formation osteoclasts
 retards formation of osteoblasts
 increase tubular reabsorb of Ca and decrease same of PO4

Question 19

Vitamin D (Vit D2 and Vit D3)

Answer 19

 diet and skin + UV
 Vit D2 and D3 same metabolism and bio. act.
 D2/D31,25[OH]2D3 = active form
 control GI Ca absorb

Question 20

Calcitonin

Answer 20

-hypercalcemia stimulus
-thyroid gland
-reduce bone reabsorption
 - decreases osteoclast and increases osteoblast

Question 21

Sex Hormones

Answer 21

• estrogen stim osteoblast
• testosterone increase bone thickness and epiphyseal closure
  - low test –> osteoporosis

Question 22

Growth Hormone

Answer 22

N/A

Question 23

Weight Bearing

Answer 23

• Stimulates osteoblast activity

- electrical potential ?

Question 24

Glucocorticoids

Answer 24

• Protein breakdown - bone collagen

Question 25

Vitamins A and C

Answer 25

N/A

Question 26

Factors that Retard Bone Formation

Answer 26

``` Estrogen/androgen deficiency Vitamin deficiency Starvation Diabetes Steroids Inactivity/Immobility Heparin Excess parathyroid hormone ```

Question 27

Bone Mass across the Life Span

Answer 27

* Peaks in third decade * Stable until approx 50 yrs women * Stable until approx 60 yrs men * Slowly declines (1% per year) * Women accelerated after menopause for a few years (2-3% year) * Men decline more slowly

Question 28

Why bone mass decrease with age?

Answer 28

• Net bone loss: | Because rate of resorption of old bone is faster than deposition of new bone.

Question 29

Why the Sex Differences ?

Answer 29

* Men initial bone mass is more, so takes longer for the decline to lead to disease * Men begin decline later than women * Men do not have menopause

Question 30

What is a Joint? | Articulations

Answer 30

- functional junctions between bones - classified by type of tissue - ---fibrous - ---cartilaginous - ----synovial - classified by degree of movement - ----synarthroses: immovable amphiarthroses: slightly movable diarthroses: freely movable

Question 31

What is a Joint?

Answer 31

``` A. Fibrous joints B. Cartilaginous joints C. Synovial joints 1. ball-and-socket 2. condyloid 3. gliding joints 4. hinge joint 5. pivot joint 6. saddle joint ```

Question 32

Fibrous Joints

Answer 32

- bones in close contact - thin layer of fibrous connective tissue - no movement: e.g. skull - limited move: e.g. leg - between tibia and fibula

Question 33

Cartilaginous Joints

Answer 33

-connect two bones with discs of fibrocartilage or hyaline cartilage -disc: ---band of fibrous tissue surrounding gelatinous core ---absorb shock and equalize pressure - limited movement: Vertebrae

Question 34

Synovial

Answer 34

-synovial membrane - lubrication -free movement: e.g. knee -complicated structure bursae - fluid sacs shock absorb menisci - fibrocartilage

Question 35

Ligaments and Tendons

Answer 35

See next cards

Question 36

Ligaments

Answer 36

viscera to viscera bone to bone stability connective tissue

Question 37

Tendons

Answer 37

extension of muscle/connective tissue attach muscle to bone or other tissue receive innervation poor blood supply