6 Flashcards
1
Q
What are the three types of muscle tissue?
A
Skeletal, smooth, and cardiac.
2
Q
Which type of muscle tissue is voluntary?
A
Skeletal muscle tissue.
3
Q
Which type of muscle tissue is involuntary and found in the walls of hollow organs?
A
Smooth muscle tissue.
4
Q
Which type of muscle tissue is involuntary and found in the heart?
A
Cardiac muscle tissue.
5
Q
What is the basic functional unit of skeletal muscle tissue?
A
The muscle fiber or muscle cell.
6
Q
What is the name of the connective tissue layer that surrounds an individual muscle fiber?
A
Endomysium
7
Q
What is the name of the connective tissue layer that surrounds a bundle of muscle fibers?
A
Perimysium
8
Q
What is the name of the connective tissue layer that surrounds the entire muscle?
A
Epimysium
9
Q
What is the name of the structure that attaches muscle to bone?
A
Tendon
10
Q
What is the name of the structure that attaches muscle to muscle?
A
Aponeurosis
11
Q
What is the name of the protein that makes up thick filaments in skeletal muscle?
A
Myosin
12
Q
What is the name of the protein that makes up thin filaments in skeletal muscle?
A
Actin
13
Q
What is the name of the neurotransmitter released at the neuromuscular junction?
A
Acetylcholine
14
Q
What is the name of the ion that binds to troponin, allowing myosin to bind to actin?
A
Calcium
15
Q
What is the name of the process by which ATP is used to detach myosin from actin?
A
ATP hydrolysis
16
Q
What are the three types of cartilage tissue?
A
The three types of cartilage tissue are hyaline, elastic, and fibrocartilage.
17
Q
What is the perichondrium?
A
The perichondrium is a layer of dense irregular connective tissue that surrounds the cartilage and contains blood vessels that nourish the cartilage cells.
18
Q
What is the most abundant skeletal cartilage?
A
Hyaline cartilage is the most abundant skeletal cartilage.
19
Q
What are the four types of skeletal hyaline cartilage?
A
The four types of skeletal hyaline cartilages are articular cartilages, costal cartilages, respiratory cartilages, and nasal cartilages.
20
Q
What are the two skeletal locations where elastic cartilages are found?
A
Elastic cartilages are found in the external ear and the epiglottis.
21
Q
What are fibrocartilages?
A
Fibrocartilages consist of roughly parallel rows of chondrocytes alternating with thick collagen fibers, and occur in sites that are subjected to both pressure and stretch.
22
Q
How does cartilage grow?
A
Cartilage grows through appositional growth and interstitial growth.
23
Q
When does cartilage growth typically end?
A
Cartilage growth typically ends during adolescence when the skeleton stops growing.
24
Q
What is calcified cartilage?
A
Calcified cartilage is cartilage that has become hardened due to deposit of calcium salts.
25
What is the difference between cartilage and bone?
Cartilage and bone are distinct tissues.
26
What are some key differences between cartilage and bone?
Some key differences between cartilage and bone are: bone is harder and has a hard matrix, while cartilage is more flexible and has a flexible matrix; bone has blood vessels, while cartilage does not; bone can repair itself more effectively than cartilage.
27
What is bone tissue?
Bone tissue, or osseous tissue, is a type of connective tissue that makes up bones. It consists of cells called osteocytes, a matrix of collagen fibers and mineral salts, and small blood vessels.
28
What are the functions of bone tissue?
Bone tissue has several important functions, including support and protection of body structures, assistance with movement, mineral storage (such as calcium and phosphorus), blood cell production in the bone marrow, and energy storage in the form of lipids.
29
What are the two types of bone tissue?
The two types of bone tissue are compact (dense) bone and spongy (cancellous) bone. Compact bone is dense and strong and makes up the outer layer of most bones, while spongy bone is less dense and more porous and makes up the inner layer of most bones.
30
What is the structure of compact bone tissue?
Compact bone tissue is composed of osteons, or Haversian systems, which are cylindrical structures that run parallel to the long axis of the bone. Each osteon contains concentric layers of bone tissue called lamellae, which surround a central canal that contains blood vessels and nerves.
31
What is the structure of spongy bone tissue?
Spongy bone tissue consists of a network of thin, bony plates called trabeculae that are arranged in a lattice-like pattern. The spaces between the trabeculae are filled with bone marrow, which produces blood cells.
32
What is bone remodeling?
Bone remodeling is the continuous process of resorption and deposition of bone tissue that occurs throughout life. It is important for maintaining bone strength and structure, and is influenced by factors such as hormones, physical activity, and diet.
33
What are the cells involved in bone remodeling?
Bone remodeling involves several types of cells, including osteoclasts (which break down bone tissue), osteoblasts (which form new bone tissue), and osteocytes (which help regulate bone remodeling by communicating with other cells).
34
What is a synapse?
A synapse is a junction between two neurons or between a neuron and a target cell.
35
What is synaptic cleft?
The synaptic cleft is a tiny gap between the presynaptic and postsynaptic membranes of a synapse.
36
What is a presynaptic neuron?
A presynaptic neuron is a neuron that sends a message across a synapse to another neuron or target cell.
37
What is a postsynaptic neuron?
A postsynaptic neuron is a neuron that receives a message across a synapse from another neuron or target cell.
38
What are neurotransmitters?
Neurotransmitters are chemical messengers that transmit signals across a synapse between neurons or from a neuron to a target cell.
39
What is synaptic vesicles?
Synaptic vesicles are small sacs in the presynaptic neuron that contain neurotransmitters.
40
What is the synaptic delay?
The synaptic delay is the brief time delay between the arrival of an action potential at the presynaptic terminal and the postsynaptic response.
41
What is synaptic fatigue?
Synaptic fatigue occurs when a synapse is stimulated repeatedly and becomes temporarily unable to transmit signals.
42
What is a neural circuit?
A neural circuit is a group of interconnected neurons that work together to perform a specific function in the nervous system.
43
What is synaptic plasticity?
Synaptic plasticity is the ability of synapses to change in strength or efficiency in response to changes in neural activity.
44
Function of Bones
Support: Bones provide a framework that supports the body and cradles its soft organs.
Protection: The fused bones of the skull protect the brain, vertebrae surround the spinal cord, and the rib cage protects the vital organs of the thorax.
Anchorage: Skeletal muscles, which attach to bones by tendons, use bones as levers to move the body and its parts.
Mineral storage: Bone is a reservoir for minerals, most importantly calcium and phosphate.
Blood cell formation: Most blood cell formation, or hematopoiesis, occurs in the red marrow of certain bones.
Triglyceride (fat) storage: Fat is stored as yellow marrow in the cavities of long bones.
Hormone production: Bones produce osteocalcin, a hormone that helps to regulate insulin secretion, glucose homeostasis, and energy expenditure.
45
In summary, what are the 7 functions of bones?
support, protection, anchorage, mineral storage, blood cell formation, triglyceride (fat) storage, hormone production
46
Periosteum
A dense fibrous membrane covering the surface of bones.
47
Diaphysis
The elongated shaft of a long bone.
48
Epiphysis
The end of a long bone.
49
Articular Cartilage
Hyaline cartilage covering the epiphysis where bone forms a joint.
50
Epiphyseal Plate
A flat plate of hyaline cartilage in the metaphysis of a growing bone.
51
Medullary Cavity
A central cavity within the shaft of the long bones filled with bone marrow in adults.
52
Endosteum
A delicate membrane lining the medullary cavity of bones.
53
Compact Bone
Dense, hard bone that forms the outer layer of bone.
54
Spongy Bone
Honeycomb of small needle-like or flat pieces called trabeculae.
55
Trabeculae
Needle-like or flat pieces that form the spongy bone.
56
Osteon
Structural unit of compact bone.
57
Lamellae
Concentric rings of hard, calcified matrix surrounding the Haversian canal.
58
Central (Haversian) Canal
Canal running through the core of each osteon containing blood vessels and nerve fibers.
59
Osteocyte
Mature bone cell.
60
Canaliculi
Hairlike canals that connect lacunae to each other and the central canal.
61
What are all parts of long bones?
Periosteum, Diaphysis, Epiphysis, Articular Cartilage, Epiphyseal Plate, Medullary Cavity, Endosteum, Compact Bone, Spongy Bone, Trabeculae, Osteon, Lamellae, Central (Haversian) Canal, Osteocyte, Canaliculi
62
What are the two types of bone tissue?
Compact bone and spongy (cancellous) bone.
63
What is compact bone and where is it found?
Compact bone is dense and looks smooth and homogeneous. It is found on the outer surfaces of bones.
64
What are osteons?
Osteons are the structural units of compact bone.
65
What are the components of an osteon?
An osteon consists of concentric lamellae, central (Haversian) canals, osteocytes, lacunae, and canaliculi.
66
What are concentric lamellae?
Concentric lamellae are circular layers of bone matrix that surround a central canal within an osteon.
67
What is the function of the central (Haversian) canal?
The central (Haversian) canal contains blood vessels and nerves that supply the osteon.
68
What are osteocytes?
Osteocytes are mature bone cells that maintain the bone matrix.
69
What are lacunae?
Lacunae are small cavities in bone that contain osteocytes.
70
What are canaliculi?
Canaliculi are hairlike canals that connect lacunae to each other and to the central canal.
71
What is spongy (cancellous) bone and where is it found?
Spongy (cancellous) bone is composed of small, needlelike pieces of bone and lots of open space. It is found in the interior of bones.
72
What are the two groups of bones in the human skeleton, and what are their relative functions?
The two groups of bones in the human skeleton are the axial skeleton and the appendicular skeleton.
73
What is the axial skeleton?
The axial skeleton forms the long axis of the body and includes the bones of the skull, vertebral column, and rib cage, which generally protect, support, or carry other body parts.
74
What is the appendicular skeleton?
The appendicular skeleton consists of the bones of the upper and lower limbs and the girdles (shoulder bones and hip bones) that attach the limbs to the axial skeleton, which help us move from place to place (locomotion) and manipulate our environment.
75
What are the four classes of bones and provide examples of each class?
The four classes of bones are long bones, short bones, flat bones, and irregular bones.
76
What are long bones?
Long bones are considerably longer than they are wide and have a shaft plus two ends, which are often expanded. Examples include all limb bones except the patella (kneecap) and the wrist and ankle bones.
77
What are short bones?
Short bones are roughly cube shaped, such as the bones of the wrist and ankle.
78
What are flat bones?
Flat bones are thin, flattened, and usually a bit curved, such as the sternum (breastbone), scapulae (shoulder blades), ribs, and most cranial bones of the skull.
79
What are irregular bones?
Irregular bones have complicated shapes that fit none of the preceding classes, such as the vertebrae and hip bones.
80
What are the different levels of bone structure?
Bones have three levels of structure: gross, microscopic, and chemical.
81
What is compact bone?
Compact bone is the dense outer layer of bone that looks smooth and solid to the naked eye.
82
What is spongy bone?
Spongy bone (also called trabecular bone) is the internal honeycomb of small needle-like or flat pieces called trabeculae.
83
What is the function of red and yellow marrow in living bones?
In living bones, the open spaces between trabeculae are filled with red or yellow bone marrow.
84
What are the different types of tissue present in bones?
Bones contain nervous tissue in their nerves, cartilage in their articular cartilages, dense connective tissue covering their external surface, and muscle and epithelial tissues in their blood vessels.
85
What is the structure of short, irregular, and flat bones?
Short, irregular, and flat bones consist of thin plates of spongy bone (diploë) covered by compact bone. They contain bone marrow (between their trabeculae), but no well-defined marrow cavity.
86
What is the structure of a typical long bone?
A typical long bone has a shaft (diaphysis), bone ends (epiphyses), and membranes (periosteum and endosteum).
87
What is the function of the sarcoplasmic reticulum?
The sarcoplasmic reticulum is a specialized smooth endoplasmic reticulum that regulates calcium ion concentration in the cytoplasm of muscle cells, which is essential for muscle contraction.
88
What is a triad in muscle physiology?
A triad is a group of three structures consisting of two terminal cisternae of the sarcoplasmic reticulum and a T-tubule that surrounds them. Triads are important for transmitting the electrical signal that triggers muscle contraction from the surface of the muscle fiber to the interior.
89
What is the sliding filament theory?
The sliding filament theory is the mechanism by which muscle cells contract. It proposes that muscle fibers shorten or contract when the thin filaments slide past the thick filaments, causing the sarcomere (the basic contractile unit of a muscle) to shorten.
90
What is the role of ATP in muscle contraction?
ATP is the energy source that fuels muscle contraction. When ATP is hydrolyzed (broken down) into ADP and inorganic phosphate, energy is released that allows myosin to bind to actin and move the thin filaments towards the center of the sarcomere.
91
What is a motor unit?
A motor unit is a motor neuron and all of the muscle fibers that it innervates. Motor units are responsible for initiating and controlling muscle contraction.
92
What is the neuromuscular junction?
The neuromuscular junction is the point of contact between a motor neuron and a muscle fiber. At the neuromuscular junction, the motor neuron releases a neurotransmitter called acetylcholine, which triggers the muscle fiber to contract.
93
What is the role of calcium ions in muscle contraction?
Calcium ions are essential for muscle contraction because they bind to the regulatory protein troponin, causing a conformational change that exposes binding sites on actin for myosin to attach. Calcium ions also trigger the release of additional calcium ions from the sarcoplasmic reticulum, which amplifies the strength of the muscle contraction.
94
What is the difference between isometric and isotonic muscle contractions?
Isometric muscle contractions occur when the muscle generates force but does not change length (e.g. pushing against an immovable object). Isotonic muscle contractions occur when the muscle generates force and changes length (e.g. lifting a weight).
95
What is muscle fatigue?
Muscle fatigue is the inability of a muscle to maintain force production after prolonged activity. It is caused by a variety of factors, including depletion of energy stores (e.g. ATP), accumulation of metabolic byproducts (e.g. lactic acid), and impaired calcium ion regulation.
96
What is muscle tone?
Muscle tone refers to the partial contraction of resting muscles, which helps to maintain posture and joint stability. Muscle tone is regulated by the central nervous system and is influenced by factors such as muscle length, muscle strength, and muscle activity.
97
What is the name of the white, double-layered membrane that covers the external surface of the entire bone except the joint surfaces?
Periosteum
98
What is the outer fibrous layer of the periosteum made of?
Dense irregular connective tissue
99
What is the inner osteogenic layer of the periosteum responsible for?
It contains osteoprogenitor cells, osteoclasts, and osteoblasts.
100
What type of cells does the endosteum contain?
It contains the same cell types as the inner layer of the periosteum.
101
What is red marrow?
Hematopoietic (blood-forming) tissue.
102
Where is hematopoietic tissue found in infants?
In infants, the medullary cavity of the diaphysis and all areas of spongy bone.
103
Where is yellow marrow found in adults?
In adults, yellow marrow is found in the medullary cavity of most long bones, and it also extends well into the epiphysis. In most adult long bones, little red marrow is present in the spongy bone cavities.
104
What are bone markings?
Distinct bone markings that provide a wealth of information about how that bone and its attached muscles and ligaments work together.
105
Name the three categories of bone markings.
Projections that are sites of muscle and ligament attachment, surfaces that form joints, and depressions and openings for blood vessels and nerves.
106
Name one example of each of the three categories of bone markings.
Tuberosity (projections), Head (surfaces), Groove (depressions and openings).
107
What are osteoprogenitor cells?
Mitotically active stem cells found in the membranous periosteum and endosteum that differentiate into osteoblasts when stimulated
108
What are osteoblasts?
Bone-forming cells that secrete the bone matrix including collagen and calcium-binding proteins; can differentiate into bone lining cells or osteocytes
109
What are osteocytes?
Mature bone cells that occupy spaces called lacunae; monitor and maintain the bone matrix, act as stress or strain "sensors," and communicate with osteoblasts and osteoclasts for bone remodeling
110
What are bone lining cells?
Flat cells found on bone surfaces where bone remodeling is not occurring that are thought to help maintain the bone matrix
111
What are osteoclasts?
Giant multinucleate cells located at sites of bone resorption that are derived from the same white blood cell lineage that gives rise to macrophages; have a ruffled border that directly contacts the bone and enzymatically degrade the bones
112
What is the structural unit of compact bone?
Osteon (Haversian system), which is an elongated cylinder oriented parallel to the long axis of the bone and composed of hollow tubes of bone matrix called lamellae, with central canals containing small blood vessels and nerve fibers that serve the osteon's cells, and perforating canals connecting the blood and nerve supply of the medullary cavity to the central canals
113
What is the function of the axial skeleton?
The axial skeleton provides support and protection for the brain, spinal cord, and vital organs of the thorax.
114
What are the bones of the skull?
The bones of the skull include the frontal, parietal, temporal, occipital, sphenoid, and ethmoid bones.
115
What is the function of the fontanelles?
The fontanelles are soft spots on a baby's skull that allow for growth and molding during childbirth.
116
What are the three types of vertebrae and where are they located?
The three types of vertebrae are cervical (located in the neck), thoracic (located in the chest), and lumbar (located in the lower back).
117
What is the function of intervertebral discs?
Intervertebral discs act as shock absorbers and provide cushioning between vertebrae.
118
What are the three parts of the sternum?
The three parts of the sternum are the manubrium, body, and xiphoid process.
119
What is the function of the rib cage?
The rib cage protects the organs in the thoracic cavity, including the heart and lungs.
120
What is the difference between true ribs, false ribs, and floating ribs?
True ribs (1-7) attach directly to the sternum via costal cartilage; false ribs (8-12) attach indirectly to the sternum via costal cartilage; and floating ribs (11-12) do not attach to the sternum at all.
121
What is scoliosis?
Scoliosis is a condition in which the spine curves sideways, often causing uneven shoulders or hips.
122
What is kyphosis?
Kyphosis is a condition in which the spine curves outward at the thoracic level, causing a hunchback appearance.
123
What is ossification?
Ossification is the process of bone tissue formation.
124
What is the difference between endochondral and intramembranous ossification?
Endochondral ossification involves replacing hyaline cartilage with bone tissue, while intramembranous ossification involves the development of bone from fibrous membranes.
125
What is the purpose of using flexible structures to fashion the embryonic skeleton?
The purpose of using flexible structures like membranes and cartilages to fashion the embryonic skeleton is that they can accommodate mitosis. If the early skeleton was composed of calcified bone tissue from the outset, growth would be much more difficult.
126
What is the primary ossification center?
The primary ossification center is the area in the center of the diaphysis where a bone collar forms around the hyaline cartilage model.
127
What happens during step 3 of endochondral ossification?
During step 3 of endochondral ossification, the periosteal bud invades the internal cavities, and spongy bone forms.
128
What happens during step 5 of endochondral ossification?
During step 5 of endochondral ossification, the epiphyses ossify through secondary ossification centers that reproduce almost exactly the events of primary ossification.
129
What is the neuromuscular junction?
The neuromuscular junction is the point where a motor neuron connects with a muscle fiber.
130
What is a motor unit?
A motor unit is a motor neuron and all the muscle fibers it innervates.
131
What is the role of acetylcholine in muscle contraction?
Acetylcholine is a neurotransmitter that binds to receptors on the motor end plate of a muscle fiber, triggering depolarization and muscle contraction.
132
What is the sliding filament theory of muscle contraction?
The sliding filament theory of muscle contraction proposes that muscle fibers contract by the sliding of thin actin filaments over thick myosin filaments, shortening the sarcomeres.
133
What is the role of calcium ions in muscle contraction?
Calcium ions bind to troponin, causing a conformational change in tropomyosin and exposing the active sites on actin filaments, allowing for myosin to bind and initiate muscle contraction.
134
What is muscle fatigue?
Muscle fatigue is the decline in muscle tension that occurs after prolonged activity, which can be caused by a lack of ATP, buildup of lactic acid, or failure of the neuromuscular junction.
135
What is the difference between isotonic and isometric muscle contractions?
Isotonic contractions involve a change in muscle length, while isometric contractions involve tension without a change in length.
136
What is a twitch contraction?
A twitch contraction is a brief contraction of all the muscle fibers in a motor unit in response to a single action potential.
137
What is a tetanic contraction?
A tetanic contraction is a sustained contraction of a motor unit in response to repeated stimuli.
138
What is muscle tone?
Muscle tone is the small amount of tension present in a muscle at rest, which helps maintain posture and stability.
139
What is bone remodeling?
Bone remodeling is the process of bone deposition and removal that occurs continuously in the adult skeleton.
140
What is the function of bone resorption?
The function of bone resorption is to remove old or damaged bone tissue.
141
What is the function of bone deposition?
The function of bone deposition is to add new bone tissue to the skeleton.
142
What are the cells involved in bone remodeling?
Osteoblasts, osteocytes, and osteoclasts are the cells involved in bone remodeling.
143
What is an osteoid seam?
An osteoid seam is an unmineralized band of gauzy-looking bone matrix that is deposited by osteoblasts during bone deposition.
144
Where does bone remodeling primarily occur in the adult skeleton?
Bone remodeling primarily occurs at the endosteal surface in the adult skeleton.
145
What cells accomplish bone resorption?
Osteoclasts accomplish bone resorption by secreting acid and lysosomal enzymes that dissolve the bone minerals and organic matrix.
146
How does the osteoid become calcified during bone deposition?
The proteins of the newly deposited osteoid bind calcium ions, raising the local concentration of calcium. This triggers osteoblasts to release matrix vesicles studded with the enzyme alkaline phosphatase, which cuts phosphate ions off of the osteoid proteins, raising the local concentration of phosphate. When the concentrations of calcium and phosphate are high enough, tiny calcium phosphate crystals form and act as seeds around which hydroxyapatites form.
147
How is bone remodeling regulated?
Bone remodeling is regulated by two control loops: a hormonal negative feedback loop involving parathyroid hormone that maintains homeostasis in the blood, and mechanical and gravitational forces acting on a bone that drive remodeling where it is required to strengthen that bone.
148
Why is maintaining extracellular fluid calcium levels within homeostatic levels critical?
Maintaining extracellular fluid calcium levels within homeostatic levels is critical for maintaining the resting membrane potential of all cells. Without normal levels of blood calcium, nerves cannot fire as needed and muscles are unable to contract.
149
What is bone growth and how does it differ in length and thickness?
Bone growth is the process by which bone tissue forms. There are two types of bone growth: appositional growth and interstitial growth. Appositional growth is growth in bone thickness and occurs at the bone's outer surface. Interstitial growth is growth in bone length and occurs at the bone's epiphyseal plate.
150
What are the major hormones involved in bone growth?
The major hormones involved in bone growth are growth hormone, thyroid hormone, estrogen, and testosterone. Growth hormone and thyroid hormone stimulate bone growth, while estrogen and testosterone promote the growth spurt at puberty and later induce epiphyseal closure.
151
What is the role of mechanical stress in bone growth?
Mechanical stress on bones stimulates bone growth by increasing bone density and strength. Bones that are not subjected to sufficient stress may become weaker and thinner over time.
152
What are some factors that influence bone growth and remodeling?
Factors that influence bone growth and remodeling include diet, hormonal balance, physical activity, and age. Adequate calcium and vitamin D intake, as well as appropriate exercise, are necessary for optimal bone health. Hormonal imbalances, such as those associated with menopause, can lead to bone loss. Older individuals generally have slower bone turnover and may be at increased risk of osteoporosis.
153
How do bone fractures heal?
Bone fractures heal by a process called fracture repair. This process involves hematoma formation, soft callus formation, hard callus formation, and remodeling. During hematoma formation, blood vessels in the bone break, leading to bleeding and the formation of a blood clot. Soft callus formation involves the deposition of fibrocartilage and hyaline cartilage. Hard callus formation involves the deposition of bony tissue. Remodeling involves the replacement of immature bone tissue with mature bone tissue.
154
What percentage of calcium is contained in the extracellular fluid?
Less than 0.1% of calcium is in the extracellular fluid.
155
What is the role of hormones in regulating calcium levels?
Hormones use the vast amount of calcium in bone as a "storage bank" from which they can make withdrawals (resorption) or deposits as needed to maintain extracellular fluid calcium levels.
156
What is the active form of vitamin D that controls calcium absorption from the intestine?
Calcitriol is the active form of vitamin D that controls calcium absorption from the intestine.
157
Which hormone is produced by the parathyroid glands to regulate blood calcium levels?
Parathyroid hormone (PTH) is produced by the parathyroid glands to regulate blood calcium levels.
158
What is Wolff's law?
Wolff's law holds that a bone grows or remodels in response to the demands placed on it.
159
What is the primary function of parathyroid hormone (PTH) in bone remodeling?
PTH stimulates osteoclasts to resorb bone, releasing calcium ions into the blood to maintain extracellular fluid calcium levels.
160
What is the primary function of calcitonin in bone remodeling?
Although calcitonin is produced by parafollicular cells of the thyroid gland and thought to regulate blood calcium levels, in humans, its effects on calcium homeostasis are negligible.
161
What is the effect of glucocorticoids on bone resorption and deposition?
Glucocorticoids stimulate osteoclast activity by increasing the synthesis of RANK-L and decreasing the synthesis of its antagonist, osteoprotegerin.
162
What is the effect of sex hormones on bone resorption and deposition?
Sex hormones have the opposite effect of glucocorticoids, as they increase the synthesis of RANK-L's antagonist.
163
What is Wolff's law?
Wolff's law states that a bone grows or remodels in response to the demands placed on it.
164
How does mechanical stress affect bone remodeling?
Bone remodeling responds to mechanical stress, as a bone grows or remodels in response to the demands placed on it. Bending compresses the bone on one side and subjects it to tension on the other, and in response, the compact bone of long bones is thickest where bending stresses are greatest.
165
How do mechanical forces communicate with the cells responsible for bone remodeling?
Deforming bone pushes fluid containing ions through the canaliculi, creating an electrical current that triggers cellular responses in the cells responsible for bone remodeling.
166
What is bone repair?
Bone repair is the process of self-repair that bones undergo after they have been fractured.
167
What are the steps involved in bone repair?
The steps involved in bone repair include hematoma formation, fibrocartilaginous callus formation, bony callus formation, and bone remodeling.
168
What is a fracture?
A fracture is a break in a bone.
169
How are fractures classified?
Fractures may be classified by the position of the bone ends after fracture, the completeness of the break, and whether the bone ends penetrate the skin.
170
What are the common types of fractures?
The common types of fractures include comminuted, spiral, depressed, compression, epiphyseal, and greenstick fractures.
171
What is reduction in the context of fracture treatment?
Reduction is the realignment of the broken bone ends.
172
How is a broken bone immobilized during the healing process?
A broken bone is immobilized either by a cast or traction to allow healing.
173
What is a hematoma?
A hematoma is a collection of blood that forms at the fracture site when blood vessels in the bone and periosteum are torn.
174
What is a callus?
A callus is a mass of repair tissue that forms at the fracture site and connects the broken bone ends.
175
What is bone remodeling?
Bone remodeling is the process by which the excess material on the diaphysis exterior and within the medullary cavity is removed and compact bone is laid down to reconstruct the shaft walls.
176
What is the primary function of cardiac muscle tissue?
To move substances through the body, such as food through the digestive tract.
177
What is the structure of skeletal muscle tissue?
Skeletal muscle tissue is striated and composed of long, cylindrical fibers that are multinucleated.
178
What is the primary function of cardiac muscle tissue?
To pump blood through the circulatory system.
179
What is the structure of smooth muscle tissue?
Smooth muscle tissue is nonstriated and composed of spindle-shaped cells that have a single, centrally located nucleus.
180
What is the structure of cardiac muscle tissue?
Cardiac muscle tissue is striated and composed of branched, cylindrical cells that have one or two centrally located nuclei.
181
What is a sarcomere?
The basic unit of muscle contraction, composed of overlapping myofilaments.
182
What are the two types of myofilaments?
Thick and thin myofilaments.
183
What is the sliding filament theory?
The theory that muscle contraction occurs as the thin filaments slide past the thick filaments, causing the sarcomere to shorten.
184
What is osteomalacia?
Osteomalacia is a disorder in which the bones are poorly mineralized, causing them to be soft and weak. The main symptom is pain when weight is put on the affected bones.
185
What is rickets?
Rickets is a disease analogous to osteomalacia that affects children. It is much more severe than adult osteomalacia and can cause bowed legs, deformities of the pelvis, skull, and rib cage, and visibly enlarged and abnormally long bones.
186
What causes osteomalacia and rickets?
Osteomalacia and rickets are caused by insufficient calcium in the diet or by a vitamin D deficiency.
187
How can osteomalacia and rickets be treated?
Increasing vitamin D intake and exposing the skin to sunlight (which spurs the body to form vitamin D) usually cures these disorders.
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What is osteoporosis?
Osteoporosis is a group of diseases in which bone resorption outpaces bone deposit. The bones become porous and light, making them fragile and prone to breaking.
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Who is most at risk for developing osteoporosis?
Osteoporosis occurs most often in postmenopausal women, but it can also affect men and women of all ages.
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What are some risk factors for developing osteoporosis?
Decreased sex hormones, low body weight or insufficient weight-bearing exercise, a diet poor in calcium, vitamin D, or protein, smoking, genetics, hormone-related conditions, consumption of alcohol or certain medications can all contribute to osteoporosis.
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How can osteoporosis be prevented and treated?
Osteoporosis can be prevented, or at least delayed, by minimizing the risk factors listed above that you can control. In particular, have an adequate diet and get lots of load-bearing exercise. Osteoporosis is treated with weight-bearing exercise and by ensuring that calcium and vitamin D intake is adequate. A number of different categories of drugs are also available.
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What is Paget's disease?
Paget's disease is a condition characterized by excessive and haphazard bone deposit and resorption. The newly formed bone is hastily made and has an abnormally high ratio of spongy bone to compact bone, causing a spotty weakening of the bones.
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What are some symptoms of Paget's disease?
Paget's disease may affect any part of the skeleton, but it is usually a localized condition. The spine, pelvis, femur, and skull are most often involved and become increasingly deformed and painful.
