Skeletal system Flashcards
(105 cards)
1
Q
Components of the skeletal system
A
bones, cartilage, ligaments, other connective tissues
2
Q
bone
A
Primary organs of the system, form rigid framework of the the body, perform multiple other functions
Types: compact and spongy
3
Q
Compact bone
A
dense or cortical bone; relatively dense connective tissue; appears white, smooth, and solid; 80% of bone mass
4
Q
Spongy bone
A
cancellous or trabecular bone; located internal to compact bone; appears porous; 20% of bone mass
5
Q
Cartilage
A
Semi- rigid connective tissue; more flexible than bone
Types: Hyaline cartilage, fibrocartilage
6
Q
Hyaline cartilage
A
attaches ribs to the sternum; covers the ends of some bones, cartilage within growth plates; model for formation of most bones
7
Q
Fibrocartilage
A
Weigh- bearing cartilage that withstands compression; forms intervertebral disks and cartilage pads of the knees
8
Q
Ligaments
A
anchors bone to bone
9
Q
Tendons
A
anchors muscle to bone
10
Q
In what 3 locations do you use fibrocartilage?
A
Intervertebral disks, the pubic symphysis, and the cartilage pads of the knee joints
11
Q
Basic functions of bone
A
Support and protection; movement; hematopoiesis; storage of mineral and energy reserves
12
Q
Hematopoiesis
A
The process of blood cell production, occurs in red bone marrow connective tissues and contains stem cells that form blood cells and platelets.
13
Q
Calcium is one of the minerals stored and released from bone. What are some of its functions within the body?
A
Muscle contracting, blood clotting, nerve impulse transmission
14
Q
Classification of bones
A
Determines by shape: long bone, short bone, flat bones, irregular bones
15
Q
Long bones
A
Greater in length than width; have elongated, cylindrical shaft (diaphysis); most common bone shape, found in upper and lower limbs; vary in size; ex. femur, humerus
16
Q
Short bones
A
Length nearly equal to width; carpal bones (wrist bones); sesamoid bones- bones along tendons of muscles; patella, targets sesamoid bone
17
Q
Flat bones
A
Flat, thin surfaces, may be slightly curves; provides surfaces for muscle attachment; protecting underlying soft tissue; form: roof of the skull, scapulae, the sternum, the ribs
18
Q
Irregular bones
A
Have elaborate shapes; vertebrae, ossa coxae; (hip bones); several bones in the skill (ethmoid, sphenoid)
19
Q
What types of bones have a length nearly equal to their width?
A
Short bones
20
Q
Diaphysis
A
Elongated, usually cylindrical shaft; provides for leverage and major weight support; compact bone within thin spicules of spongy bone extending inward
21
Q
Epiphysis
A
Knobby regions at the ends of ling bone; Proximal epiphysis (closest to the trunk); Distal epiphysis (furthest from the trunk); made of: outer thin layer of compact bone, inner region of spongy bone (primarily spongy bone), joint surface covered by thin layer of hyaline cartilage (termed articular cartilage it helps to reduce friction and absorb shock in moveable joints)
22
Q
Metaphysis
A
region of mature bone between diaphysis and ephysis
23
Q
Periosteum
A
Tough sheath outer surface of bone; outer fibrous layer of dense irregular connective tissue; protects bone from surrounding structures; anchors blood vessels and nerves to bone surface; attachment site for ligaments and tendons; inner cellular layer includes osteoprogenitor cells, osteoblasts, and osteoclasts; attached to bone by numerous collagen fibers (perforating fibers)
24
Q
Endosteum
A
Covers all internal surfaces of bone within medullary city; incomplete layer of cells; contains osteoprogenitor cells, osteoblasts, and osteoclasts; though sheath covering outer surface of bone
25
What portion of the bone contains the epiphyseal plate?
The metaphysis
26
Gross anatomy of short, flat, and irregular bones
external surface composed of compact bone; interior composed of spongy bone (also called diploë in flat skull bones; lack a medullar cavity
27
Blood supply of bone
Bone highly vascularize, especially spongy bone; vessels entering from periosteum
28
Nutrient foramen
Small opening or hole in the bone; artery entrance and vein exit here
29
Nerve that supply bone
Accompany blood vessels through foramen; innervate bone, periosteum, endosperm, and marrow cavity; mainly sensory nerves
30
Bone marrow
soft connective tissue of bone; includes red and yellow bone marrow
31
Red bone marrow
Myeloid tissue; hematopoietic (blood cell forming); contains reticular connective tissue, immature blood cells and fat; in children located in the spongy bone and medullary cavity of long bones; in adults, located in portions of axial skeleton, located in proximal epiphyses of humerus and femur; e.g., skull, vertebrae, ribs, sternum, ossa coxae
32
Yellow bone marrow
Product of red bone marrow degeneration; fatty substance; may cover back to red bone marrow; may occur during sever anemia (condition with reduced erthyrocytes/ red blood cells) facilitates the production of additional erthyocytes
33
Where is red bone marrow found in the adult skeleton?
Proximal epiphyses of humerus and femur and portions of the axial skeleton: skull, vertebrae, ribs, sternum, and ossa coxae
34
Bone connective tissue
Primary components of bone, also called osseous connective tissue, composed of cells and extracellular matrix
35
Cells of the bone
Osteoprogenitor cells, osteoblasts, osteocytes, osteoclasts
36
osteoprogenitor cells
Stem cells derived from mesnchyme; produced cells that mature to become osteoblasts; located in periosteum and endosteum
37
osteocytes
mature bone cells derived form osteoblasts; have lost bone forming ability; maintain bone matrix; detect mechanical stress on bone; may trigger deposition of new bone matrix
38
osteoblasts
often positioned side by side on bone surfaces; synthesized and secrete osteoid, initial semisolid form of bone matrix, later calcify; become entrapped within the matrix they produce
39
osteoclasts
large, multicellular, phagocytic cells; derived from fused bone marrow cells; ruffled border to increase surface area exposed to bone; often located within or adjacent to a depression or pit on bone, termed resorption lacuna; involved in break down bone
40
Organic components
osteoid produced by osteoblasts: collagen protein, semisolid ground substance of proteoglycans, glycoproteins; give bone tensile strength by resisting stretching; contribute to bone flexibility
41
Inorganic components
Made of salt crystal, primarily calcium phosphate, Ca3(PO4)2; Interacts with calcium hydroxide, forms crystals of hydroxyapatite Ca10(PO4)6(OH)2; other substance incorporated into crystal, e.g., calcium, carbonate, sodium, magnesium ions; crystals deposited around collagen fibers; harden the matrix and account for relative rigidity of bones
42
Proportion of organic and inorganic substances
correct proportion allows optimal functioning; loss of protein resulting in brittle bones; insufficient calcium resulting in soft bones
43
Bone formation
Begins with secretion of osteoid
Proceeds with calcification, when hydroxyapatite crystals deposited (calcium phosphate ions precipitating out forming crystals)
Process requires Vitamin D (enhances calcium absorption from gastrointestinal tract)
Requires vitamin C (Needed for collagen formation)
Requires calcium and phosphate for calcification
44
Bone Resorption
Bone matrix destroyed by substances released from osteoclasts; proteolytic enzymes released from lysosomes within osteoclasts (chemically digest organic matrix components); calcium and phosphate dissolved by hydrochloric acid; may occur when blood calcium levels low
45
Compact spongy bone microscopic anatomy
Compact bone composed of osteons; small cylindrical structures, also known as Haversian system, basic functional and structural unit of mature compact bone, oriented parallel to bone diaphysis, in cross appears like bull's-eye target
46
Components of osteons of compact bone
Central Canal, concentric lamellae, osteocytes, canaliculi,
47
Central Canal
Cylindrical channel, lies at center of osteons and runs parallel to it, blood vessels and nerves traveling here
48
Concentric lamellae
Rings of bone bone connective tissue, surrounding the central canal, contain collagen fibers, oriented at an angle 90 degrees from previous and next lamellae, give bone part of its strength and resilience
49
Osteocytes
Mature bone cells, found in small spaces between concentric lamellae (lacunae), maintain bone matrix
50
Canaliculi
Tiny interconnecting channels within bone connective tissue, extends from each lacuna, travel through lamellae, connect to other lacunae and central canal, house osteocyte projections permitting intercellular contact, allow travel of nutrients, minerals, gases, and wastes between blood vessels and osteocytes
51
Perforating canals (Volkmann Canals)
Contains blood vessels and nerves, run perpendicular to the central canals, help connect multiple central canals within different osteons
52
Circumferential lamellae
Rings of bone, may run immediately internal to bone periosteum (external circumferential lamellae), may run internal to the endosperm (internal circumferential lamallae) run the entire circumference of bone
53
Interstitial lamellae
May be components of compact bone between osteons, may be partially resorbed osteons, look like a "bite" taken out of them
54
What is the function of an osteoblast? An osteoclast?
Osteoblast secrete osteoid and build bone
Osteoclasts break down (resorb) bone
55
What organic substances compose bone matrix? what inorganic substance?
Organic component- Osteoid, composed of collagen, proteoglycans, and glycoproteins
Inorganic component- hydroxyapatite, which includes calcium phosphate. Other salts and ions are also incorporated, e.g., calcium carbonate and magnesium ions
56
Structure of hyaline cartilage
Population of cells scattered through matrix of protein fibers; embedded in a gel-like grout substance, included proteoglycans but not calcium; resilient and flexible; high percentage of water; highly compressible and a good shock absorber; avascular and contains no nerves
57
Chondroblasts
produce cartilage matrix
58
Chondrocytes
Chondroblasts that have become encased within the matrix, occupy small spaces called lacunae, maintain matrix
59
Perichondrium
dense irregular connective tissue, convers cartilage and helps maintain its shape
60
What cells secrete the cartilage matrix? What cells maintain matrix?
Chondroblasts secrete the cartilage matrix. Mature chondroblasts trapped in the matrix are known as chondrocytes. They maintain the matrix
61
Process of cartilage growth
Begins during embryological development; growth in length through interstitial growth (occurs within the internal regions of cartilage); growth in width by appositional growth (occurs on cartilage's outside edge)
62
Steps of Interstitial growth
1. a chondrocyte within a lacuna is stimulates to mitotically divide
2. 2 cells, how called chondroblasts, occupy a single lacuna
3. Chondroblasts secrete new material and are pushed apart. Each is now called a chondrocyte
4. Cartilage continues to grow internally
63
Steps of Appositional growth
1. mitotic activity occurs in stem cells within the perichondrium
2. New undifferentiated stem cells and new chondroblasts are formed. Chondroblasts produce new matrix at the periphery of old cartilage.
3. Chondroblasts push apart and become chondrocytes
64
Where does interstitial growth of cartilage occur? Appositional growth?
Interstitial growth- internal regions of cartilage
Appositional growth- along the cartilage's outside edge
65
Ossification
Osteogenesis, the formation and development of bone connective tissue; begins in embryo; continues through childhood and adolescence; begins by the 8th-12th week of embryonic development; occurs through intramembrous ossification or echondrial ossicication
66
Intramembranous ossification
Dermal ossification
Produces: flat bones of the skulll, some of the facial bones, mandible, central part of the clavicle
Begins when mesenchyme become thickened with capillaries
67
steps of intramembranous ossification
1. Ossification centers form within thickened regions of mesenchyme (some cells becoming osteoprogenitor cells, some cells becoming osteoblasts secreting osteoid)
2. Osteoid undergoes calcification (calcium slats deposited onto osteoid and crystalize, entrapped cells become osteocytes)
3. Woven bone and surrounding periosteum form (At first, bone immature and poorly organized, termed woven bone which is primary bone, mesenchyme surrounding woven bone beginning to form periosteum)
4. Lamellar bone (secondary bone) replaced woven bone (compact and spongy bone formed trabecular, typical structure of a flat cranial bone which is composed of 2 external layers of compact bone, layer of spongy bone in between)
68
What bones are formed from intramembranous ossification?
Flat bones of the skill, some of the facial bones, the mandible, the central part of the clacivle
69
Endochondral ossification
Begins with hyaline cartilage model, produces most of the bone os the skeleton including: bones of the upper and lower limns, pelvis, vertebrae, ends of the clavicle
70
Steps of long bone development
1. Fetal hyaline cartilage model develops
2. cartilage calcifies, and a periosteal bone collar forms around diaphysis
3. Primary ossification centers forms in the diaphysis
4. secondary ossification centers form in epiphyses
5. Bone replaces cartilage, expect articular cartilage and epiphyseal plates
6. Epiphyseal plates ossify and form epiphyseal line
71
In what portion of a long bone do primary ossification centers form? Secondary ossification centers?
Primary ossification centers- the diaphysis
Secondary ossification centers- the epiphyses
72
Zones of epiphyseal plate
zone of resting cartilage, zone of proliferating cartilage, zone of hypertonic cartilage, zone of calcified cartilage, zones of ossifcation
73
zone of resting cartilage
Nearest the epiphysis, composed of small chondrocytes disturbed throughout the matrix, resembles mature hyaline cartilage, secures epiphysis to epiphyseal plate
74
zone of proliferating cartilage
Chondrocytes undergo rapid mitotic divison, become aligned into longitudinal columns of flattened lacunae, columns parallel to diaphysis
75
zone of hypertonic cartilage
Chondrocytes cease to divide, chondrocytes being to hypertrophy, walls of the lacunae become thin
76
zone of calcified cartilage,
Composed of 2-3 layers of chondrocytes, minerals deposited between columns of lacunae, destroy chondrocytes
77
zones of ossifcation
Walls break down between lacunae in columns, spaces invade by capillaries and osteoprogenitor cells, new bone matrix deposited on the calcified cartilage matrix
78
Bone growth in length
Occurs specifically within zone 2 (proliferating cartilage) and zone 3 (hypertonic cartilage), pushed zone of resting cartilage toward the epiphysis, flexible hyaline cartilage permitting growth, new hyaline cartilage replaced by bone, similar to endochondral ossification during development
79
What is the term for bone growth in width? For bone growth in length?
width- appositional growth
length- interstitial growth
80
Bone remodeling
continual process of bone deposition and resorption; occurs at periosteal and endosteal surfaces of the bone; occur at different rates; 20% of the skeleton is replaces yearly; dependent on then coordinated activities of osteoblasts, osteocytes, and osteoclasts
81
Mechanical stress (bone remodeling)
Occurs in weight-bearing movement and exercise; required for normal bone remodeling; detected by osteocytes and communicated to osteoblasts; causes increase in bone strength; resulted from skeleton contraction and gravitational forces
82
Increased bone mass (bone remodeling)
From weight-bearing activities; can increase total bone mass throughout the lifetime
83
Decreased bone mass (bone remodeling)
From removal of mechanical stress; reduced collagen formation, demineralization
84
Hormones (bone remodeling)
Molecules released from one cell into the blood; travel through the body to affect other cells; bind to cellular changes; initiate specific cellular changes; some altering rates of chondrocytes, osteoblasts, and osteoclast activity's affect bone composition and growth patterns
85
Growth hormones
Somatotropin, produced by then anterior pituitary gland; stimulates the liver to produce somatomedin
86
Thyroid Hormone
Secreted by thyroid gland; influences basal metabolic rate of bone cells; helps regulate normal activity at the epiphyseal plates
87
Sex Hormones
Estrogen, Testosterone; begin to be secreted in large amounts at puberty; dramatically accelerate bone growth; Increase rate of cartilage growth and bone formation in epiphyseal plate; results in increased length of bones; bone formation rate greater than cartilage growth; growth plates closing more quickly in response to estrogen
88
Glucocorticoids
Group of steroid hormones; released from adrenal cortex; regulate blood glucose level; cortisol the primary glucocorticoid; high amounts of increasing bone loss
89
Serotonin
Neurotransmitter and hormone; most bones with serotonin receptors; plays a role in rate and regulation of normal bone remodeling; if levels are too high osteoprogenitor cells prevented from becoming osteoblasts
90
What hormone stimulates the liver to produce somatomedin, causing cartilage proliferation at the epiphyseal plate?
Growth hormone
91
Calcium is required for:
Initiation of muscle contraction; exocytosis of molecules from cells, including neurons; stimulation of the heart by pacemaker cells; blood clotting
92
2 primary hormones regulate blood calcium
calcitriol and parathyroid hormone
93
Activation of Vitamin D to calitriol
1. UV light converts precursor molecule in blood to vitamin D3
2. Vitamin D3 circulates through the body (both 1 and 2 occur continuously with limited regulation)
3. Calcidiol circulates in blood
94
What organs are involved in activating vitamin D3 to calcitriol?
Kidney (converts vitamine D3 to calcidiol)
Liver (which converts calcidiol to calcitriol)
95
Parathyroid hormone (PTH)
Secreted and released by parathyroid glands; secreted in response to reduced blood calcium levels; Calcitriol formed more readily in the presence of PTH
96
Actions of parathyroid hormone and calcitriol
Elevate blood calcium; return calcium within homeostatic range; regulated by negative feedback
97
PTH and calcitriol
Act synergistically to increase release of calcium from bone to blood; act synergistically to work on the kidney; calcitriol alone increasing absorption from small intestines
98
Parathyroid hormones and calcitriol are secreted in response to what?
low blood calcium levels
99
How does calcitonin work on bones connective tissue and the kidneys to regulate blood calcium levels?
Inhibits osteoclast activity (less calcium released from bone into blood)
Stimulates kidneys to increase the loss of calcium in the urine (reducing calcium blood levels)
100
Effects of again on bone
Decreased tensile strength of bone; bone loss of calcium and other minerals
101
Osteopenia
Occurs in all people with age; begins as early as age 35- 40; osteoblast activity declining, osteoclast activity at previous levels; Vertebrae, jaw bones, epiphyses losing large amounts of mass; women losing more of their skeletal mass every decade than men
102
Osteoporosis
Reduced bone mass sufficient to compromise normal function; occurs in a significant percentage of older women
103
Reduced hormones with age
include growth hormones, estrogen, and testosterone; contributes to reduction in bone mass; reduced bone mass sufficient to compromise normal function
104
What condition displays a reduction in bone mass by loss of calcium and other minerals, but without yet compromising normal function?
Osteopenia
105
4 steps to fracture healing
1. Fracture hematoma forms from clotted blood
2. Fibrocartilaginous callus forms
3. Hard (bony) callus forms
4. Bone is remodeled
