Flashcards in Muscle and Skeletal System Deck (38):
What synthesizes cartilage?
-Specialized mineralized connective tissue
-Dense bone deposited in units called osteons
-Channels called Haversian canals surrounded by bony matrix (lamellae)
-Much less dense
-Interconnecting spicules with yellow marrow (adipose) or red marrow (blood formation)
-Synthesize/secrete organic components of bone matrix - collagen
-Mature into osteocytes
-Lg, multinucleated cells
What are the methods of bone formation?
-Endochronal Ossification (cartilage)
-Intramembranous ossification (mesenchymal tissue)
Axons of pyramidal cells of motor cortex synapse on lower motor neurons
What is the extrapyramidal system?
-Somatic motor commands at the involuntary level
-Skeletal muscle tone primarily controlled by red nucleus in midbrain
-Controlled by SNS, voluntary movements
-Myofibrils (divided into sacromeres) enveloped in sarcoplasmic reticulum
-High energy requirements --> mitochondria rich
-Transverse tubules perpendicular to myofibrils
-Ion channels --> propagate action potentials
Which bands reduce in size during muscle contraction?
-I and H band
What is the neuromuscular junction?
-Link between nerve terminal and sarcolemma of muscle fiber
How is an action potential generated in muscle contraction?
-Enough neurotransmitters diffuse across cleft and stimulate receptors on sarcolemma, changing permeability
What occurs once an action potential is generated?
-Potential is conducted along sarcolemma and T system into interior of muscle fiber
-SR release Ca++ into sarcoplasm --> bind troponin C on actin --> actin/myosin slide --> sarcomere contracts
What is rigor mortis?
-Muscle contract w/o potentials due to lack of ATP which is needed to release myosin heads from actin filaments
-Muscle shortens against fixed load
-Concentric and eccentric contractions
-Change length of muscle and tension
-Muscle fibers shorten, tension increases
-Muscle fibers lengthen, tension increases
-Both ends of muscles are fixed, no change in length
How can strength of muscle contraction be increased?
-All or nothing response
-Increase by recruiting more muscle fibers
-Single muscle fiber to brief stimulus
-Latent, contraction, relaxation
-Contractions combine --> stronger/prolonged
-Muscle fibers continuously stimulated and can't relax
-Muscle will fatigue and contraction weakens
-Muscles are never completely relaxed
-Converts lactic acid in liver to glucose --> bloodstream
-Muscle uses glucose or stores as glycogen
-NOT include breaking down glycogen/production of lactic acid
-Digestive tract, bladder, uterus, blood vessel walls
-One central nucleus
-Smooth, continuous contractions
-Actin/myosin arranged in sarcomeres (striated)
-Only 1-2 nuclei
What are forms of energy reserves for muscles?
-Myoglobin (store oxygen)
What do the inorganic components of bone form?
-Hydroxyapatite crystals (phosphate, calcium, hydroxide)
Which bones are typically formed from endochondral ossification?
Which bones are typically formed by intramembranous ossification?
What makes up the diaphysis?
-Bone marrow surrounded by compact bone
What makes up the epiphysis?
-Spongy bone coated with thin layer of compact bone
What is the epiphyseal plate?
-Separate the diaphysis and epiphsis
-Cartilage in growing bones
-Source of longitudinal growth