bio exam

Mesenchymal cells

Stem cells that can differentiate into various cell types, including osteoblasts and chondrocytes.

Osteoblast

Bone-forming cell responsible for bone deposition.

Osteoclast

Bone-resorbing cell that breaks down bone tissue.

Chondroblast

Cartilage-forming cell that synthesizes extracellular matrix.

Cartilage vs Bone Tissue Growth

Cartilage grows mainly through interstitial and appositional growth, while bone grows through ossification.

Compact bone vs Spongy bone

Compact bone provides strength and structure; spongy bone contains red bone marrow and is lighter.

Bone Marrow

Soft tissue found within the cavities of bones, responsible for hematopoiesis.

Hematopoiesis

The process of blood cell formation, occurring in the bone marrow.

Intramembranous ossification

Bone development directly from mesenchymal tissue without prior cartilage model.

Endochondral ossification

Bone development using a cartilage model that gradually gets replaced by bone.

Ossification vs Calcification

Ossification is bone tissue formation; calcification is the deposition of calcium salts in tissue.

Epiphyseal plate vs Epiphyseal line

The plate is active in growth (growth plate); the line indicates the end of growth after puberty.

Endosteum vs Periosteum

Endosteum lines the medullary cavity; periosteum is a dense layer surrounding the outer surface of bones.

Interstitial growth vs Appositional growth

Interstitial growth increases length whereas appositional growth increases width of bones.

Parts of a long bone

Epiphysis (ends), diaphysis (shaft), metaphysis (growth plate area).

Osteon parts

Includes Haversian canal (center), lamellae (rings), lacunae (spaces for osteocytes), and perforating canals.

Function of PTH and Calcitonin

PTH increases blood calcium by stimulating osteoclasts; calcitonin lowers blood calcium by inhibiting osteoclasts.

Role of sex hormones in puberty

Sex hormones promote growth spurts and epiphyseal closure in bones.

Growth hormone origin and disorders

Secreted by the pituitary gland; associated disorders include gigantism and dwarfism.

Steps to bone repair

Include hematoma formation, callus formation, ossification, and remodeling.

Joints classification

Joints can be classified as fibrous, cartilaginous, or synovial structurally, and as synarthrosis, amphiarthrosis, or diarthrosis functionally.

Types of synovial joints

Include plane, hinge, saddle, condylar, and ball-and-socket; classified as nonaxial, uniaxial, biaxial, multiaxial.

Movements of synovial joints

Include flexion, extension, hyperextension, abduction, adduction, and depression.

Types of muscles

Skeletal (voluntary, striated, multinucleated), cardiac (involuntary, striated, single nucleus), smooth (involuntary, non-striated, single nucleus).

Cell vs Skeletal muscle fiber

Skeletal muscle fibers are specialized cells that can contract and are organized into bundles.

Muscle terms confusion

Sarcolemma (cell membrane), sarcoplasm (cytoplasm), sarcoplasmic reticulum (smooth ER), sarcomere (contractile unit), myofibril (muscle fiber bundles), myofilament (contractile structures).

Surrounding structures

Epimysium surrounds the whole muscle, perimysium surrounds fascicles, endomysium surrounds individual muscle fibers.

Fascicle vs Fascia vs Fiber

Fascicle is a bundle of muscle fibers; fascia is connective tissue surrounding muscles; fiber refers to the muscle cell.

Major filaments in muscle

Actin (thin), myosin (thick), troponin (regulatory), tropomyosin (regulatory, covers binding sites on actin).

Bands in muscle contraction

I band and H band shorten during contraction; A band remains the same length.

Neuromuscular junction function

The site where a motor neuron communicates with a muscle fiber to initiate contraction.

Actin-myosin cross bridge cycle

The process by which myosin heads bind to actin filaments to produce muscle contraction.

Muscle relaxation

Results from calcium ions being pumped back into the sarcoplasmic reticulum, leading to troponin resetting and muscle fiber relaxing.

Clinical conditions

Include polio (motor neuron damage), tetanus (excessive contraction), botulism (muscle paralysis), myasthenia gravis (autoimmune block at neuromuscular junction).

Twitch phases

Include latent phase, contraction phase, and relaxation phase; calcium binds to troponin during the contraction phase.

Treppe vs Multiple Wave Summation

Treppe shows increased tension with each stimulus; wave summation shows increasing tension without relaxation.

Incomplete vs Complete Tetanus

Incomplete tetanus has partially relaxes between contractions; complete tetanus has no relaxation and maximal tension.

Aerobic vs Anaerobic Respiration

Aerobic respiration requires oxygen and produces more ATP; anaerobic respiration occurs without oxygen and produces less ATP.

Glycolytic vs Oxidative muscle fibers

Type I fibers are slow-oxidative, Type IIa are fast-oxidative, and Type IIb are fast-glycolytic.

Isotonic vs Isometric contraction

Isotonic contractions involve change in muscle length with tension; isometric contractions involve tension without change in muscle length.

Smooth vs Skeletal muscle contraction similarities

Both involve actin and myosin and require calcium for contraction, but mechanisms of contraction differ.