Cartilage
The articular surfaces of bones are composed of _____________ cartilage
Hyaline cartilage
Name and describe the three functional classifications of joints
Synarthrosis (immoveable), amphiarthrosis (slightly moveable); diarthrosis (freely moveable)
What are the four functional characteristics of muscles and which one of them is exclusive to muscle tissue?
Excitability is the ability of a cell to receive and respond to a stimulus by changing its membrane potential. In the case of muscle, the stimulus is usually a chemical—for example, a neurotransmitter released by a nerve cell.
Contractility is the ability to shorten forcibly when adequately stimulated. This ability sets muscle apart from all other tissue types.
Extensibility is the ability to extend or stretch. Muscle cells shorten when contracting, but they can be stretched, even beyond their resting length, when relaxed.
Elasticity is the ability of a muscle cell to recoil and resume its resting length after stretching.
Where are the primary centers of ossification generally located? the secondary ossification centers?
The primary ossification center appears in shaft (diaphysis of the bone) and the secondary appears in the epiphyses shortly before or after birth
Reduced mechanical stress on bones (e.g. prolonged bed rest) leads to reduced ___________ cell activity---> decreased ______ mass
Reduced mechanical stress on bones (e.g. prolonged bed rest) leads to reduced osteoblast cell activity---> decreased bone mass
Cartilage is primarily composed of _______ and has no _________ or __________
Cartilage is primarily composed of water and has no blood vessels or nerves
Name and describe the three types of fibrous joints. Give an example of each.
Sutures: occur only between bones of the skull; junction is completely filled by a minimal amount of very short connective tissue fibers that are continuous with the periosteum. Allow skull to expand until fibrous tissue (fontanel) ossifies and skull bones fuse (synostosis)
Syndesmosis: joint held together by ligament, cords, or bands of fibrous tissue. Fibrous tissue can vary in length but is longer than in sutures. Amount of movement depends on length of connecting fibers.
Gomphosis: peg-in-socket fibrous joint. Only found in teeth with bony alveolar socket called periodontal ligament.
Of the three types of muscle tissue in the human body, which is striated and voluntary?
Skeletal muscles
What are the target sites for parathyroid hormone (PTH)?
Too little Ca in the blood-->stimulates parathyroid glands--> releases PTH--> stimulates osteoclasts to resorb bone--> blood concentrations of Ca rise-->stimulus for PTH secretion ends
Decreases rate of Ca secretion by kidneys, stimulates conversion of Vitamin D to active form in kidneys--> increased Ca absorption from food in small intestines
What are the organic portions of the bone matrix and what does it contribute to?
Osteoid, which makes up approximately one-third of the matrix, includes ground substance and collagen fibers, both of which are secreted by osteoblasts. These organic substances, particularly collagen, contribute both to a bone’s structure and to the flexibility and tensile strength that allow it to resist stretch and twisting.
Where is fibrocartilage found in the body?
Highly compressible with great tensile strength, fibrocartilages consist of roughly parallel rows of chondrocytes alternating with thick collagen fibers. Fibrocartilages occur in sites that are subjected to both pressure and stretch, such as the padlike cartilages (menisci) of the knee and the discs between vertebrae.
What structures and materials protect the bones in the articulation of a synovial joint?
Articular cartilage: hyaline cartilage covers the opposing bone surfaces as articular cartilage and absorb compression placed on the joint and thereby keep the bone ends from being crushed.
Joint (articular) cavity: has synovial fluid that reduces friction
Articular capsule: double-layered with external fibrous layer continuous with periosteum of bone and strengthens joint so bones not pulled apart. Inner synovial membrane makes synovial fluid
Reinforcing ligaments: thickened parts of fibrous layer (capsular) or outside of the capsule (extra capsular) to reinforce and connect bones
Fatty pads and articular discs
Muscle tone: muscle tendons that cross joints are most important stabilizing factor
Order from smallest to largest the organizational level of skeletal muscles starting with myofilaments.
Myofilaments, sarcomere (contractile unit), myofibril, muscle fiber, fascicle, muscle
What are the four types of bone cells and briefly describe their main function?
Osteoprogenitor cells, osteoblasts, osteocytes, osteoclasts
What type of bones make up the epiphyses?
An outer shell of compact bone forms the epiphysis exterior and the interior contains spongy bone. A thin layer of articular (hyaline) cartilage covers the joint surface of each epiphysis, cushioning the opposing bone ends during movement and absorbing stress.
Describe the zones into which chondrocytes are organized within the epiphyseal plate.
The cartilage is relatively inactive on the side of the epiphyseal plate facing the epiphysis, a region called the resting zone. Below the resting zone, the cartilage cells form tall columns, like coins in a stack, that allow fast, efficient growth.
Proliferation zone: The cells at the epiphysis-facing side of the stack next to the resting zone comprise the proliferation or growth zone. These cells divide quickly, pushing the epiphysis away from the diaphysis and lengthening the entire long bone.
Hypertrophic zone: The older chondrocytes in the stack, which are closer to the diaphysis, hypertrophy. Their lacunae erode and enlarge, leaving large interconnecting spaces.
Calcification zone: The surrounding cartilage matrix calcifies, the chondrocytes die, and the matrix begins to deteriorate, allowing blood vessels to invade. This leaves long, slender spicules of calcified cartilage at the epiphysis-diaphysis junctions, which look like stalactites hanging from the roof of a cave.
Ossification zone: The calcified spicules are invaded by marrow elements from the medullary cavity. Osteoclasts partly erode the cartilage spicules, then osteoblasts cover them with new bone. Ultimately spongy bone replaces them. Eventually, as osteoclasts digest the spicule tips, the medullary cavity also lengthens.
What is the difference between osteoarthritis and rheumatoid arthritis?
Osteoarthritis: chronic wear-and-tear. Prevalent in old age (normal aging process). breaking down of the articular cartilage, especially collagen. More damaged than is replaced. Eroded articular cartilages and bony spurs form and restricts joint movement. Crepitus. Mostly in spine, fingers, knuckles, knees, hips
RA: chronic inflammatory disorder. Age 30-50. W>M. Joint tenderness and stiffness. Small joints of the fingers, wrists, ankles, and feet, are afflicted at the same time and bilaterally. Exacerbations and remission. AUTOIMMUNE DISEASE.
What is the appearance and location of smooth muscle?
Smooth muscle tissue is found in the walls of hollow visceral organs, such as the stomach, urinary bladder, and respiratory passages. Its role is to force fluids and other substances through internal body channels. Smooth muscle also forms valves to regulate the passage of substances through internal body openings, dilates and constricts the pupils of your eyes, and forms the arrector pili muscles attached to hair follicles.
Like skeletal muscle, smooth muscle consists of elongated cells, but smooth muscle has no striations. Like cardiac muscle, smooth muscle is not subject to voluntary control. Its contractions are slow and sustained.
What is the function of the nutrient foramen?
Main vessels serving the diaphysis are a nutrient artery and a nutrient vein. Together these run through a hole in the wall of the diaphysis, the nutrient foramen. The nutrient artery runs inward to supply the bone marrow and the spongy bone. Branches then extend outward to supply the compact bone. Several epiphyseal arteries and veins serve each epiphysis in the same way. Nerves accompany blood vessels through the nutrient foramen into the bone.
Name and describe the two types of cartilaginous joints. Give an example of each.
Synchondroses: plate of hyaline cartilage unites bones and virtually all are synarthrotic (immovable). Ex. epiphyseal plates in children, costal cartilages between first rib and sternum
Symphyses: fibrocartilage unites bones. Since fibrocartilage is compressible and resilient, it acts as a shock absorber and permits a limited amount of movement at the joint. Even though fibrocartilage is the main element of a symphysis, hyaline cartilage is also present in the form of articular cartilages on the bony surfaces. Symphyses are amphiarthrotic joints designed for strength with flexibility. Ex. intervertebral joints and the pubic symphysis of the pelvis
What is the difference between appositional growth and interstitial growth of cartilages?
In appositional growth, cartilage-forming cells in the surrounding perichondrium secrete new matrix against the external face of the existing cartilage tissue.
In interstitial growth, the lacunae-bound chondrocytes divide and secrete new matrix, expanding the cartilage from within.
Why does a contracture develop? How is it prevented?
Stiffness or contracture in muscles, tendons, ligaments, joint capsules, and skin.
Caused by shortening of muscles, tendons, ligaments, and joint capsules.
Need to stretch, passive and active ROM
What are the two types of indirect muscle attachments?
Tendons: mostly tough collagen fibers, which can withstand the abrasion of rough bony projections that would tear apart the more delicate muscle tissues. Because of their relatively small size, more tendons than fleshy muscles can pass over a joint—so tendons also conserve space.
Aponeurosis: sheetlike CT
Describe the process of endochondral ossification?
1. Develop of the hyaline cartilage model
2. Growth of the cartilage model
3. Development of the primary ossification center and invasion of the periosteal bud
4. Development of the secondary ossification centers
5. Formation of the articular surfaces and epiphyseal plate
What bones develops through intramembranous ossification?
Cranial bones of the skull and the clavicles