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53 Cards in this Set
- Front
- Back
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Erythrocytes
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Red blood cells
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Leukocytes
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White blood cells
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Primary Functions of Bone
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Support, Storage of lipids and minerals, Blood cell production, Protection, Leverage
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Bone Shapes
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Long bones, Sutural (Wormian) bones, Irregular bones, Short bones, Sesamoid bones
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Long bone anatomy
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Epiphysis- spongy bone, head
Metaphysis- neck Diaphysis- shaft, compact bone and medullary cavity Periosteium- outer covering |
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2/3 of bone is:
Composed of: |
Mineral
Calcium, phosphorus, fluoride, sodium, magnesium |
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1/3 of bone is:
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Collagen- flexible, strong, resistant to pull, no resistance to compression
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Osteocyte
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Mature bone cells
Most of cell population Held within lacuna |
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Osteoblast
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Produces new boney matrix
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Osteoclast
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Remove and recycle bony matrix
Important for maintaining blood calcium levels |
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Bone Marrow
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Supplies nutrients and removes wastes via diffusion at spongy bone
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Endochondral Ossification
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Cartilage converted to bone
I. Cartilage enlarges, condrocytes in the center of shaft enlarge, die and leave calcified matrix ii. Blood vessels grow around cartilage, osteoblasts synthesize thin layer of outer bone iii. Blood vessel goes to center, osteoblasts synthesize spongy bone at center iv. Osteoclasts arrive at bone center, creates medullary cavity by dissolving spongy bone v. Blood supply and osteoblasts enter epiphysis, ossifies vi. Entire epiphysis becomes spongy bone , except at joint cavity and epiphysedal plate vii. If epiphyseal cartilage continues to grow, process continues viii. Epiphyseal closure results when the epiphyseal cartilage is ossified; increases in length cease ix. Appositional growth: widening of bone |
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Intramembranous Ossification
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Dermal bones; occurs in deep layers of dermis
i. Forms the flat bones of skull, mandible, clavicle ii. Undifferentiated cell clusters, differentiate to osteoblasts at ossification center, grow outward iii. Blood vessels grow into area |
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Remodeling
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Dynamic process of recycling and renewing bony matrix
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If calcium concentration FALLS in blood
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1) Parathyroid hormone released
2) Stimulates osteoclast activity a) Dissolves bone, releases Ca into blood 3) Increased absorption of Ca at intestines 4) Decreased excretion of Ca at kidneys 5) Homeostasis is preserved |
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If calcium concentration RISES in blood
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1) Calcitonin secreted by thyroid gland
a) Understood to be important during pregnancy, starvation, and childhood b) decreased osteoclast activity c) increased Ca excretion at kidneys 2) Osteoblasts continue to function 3) Intestinal absorption of calcium is reduced |
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Rickets
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Vit D required for Ca absorption
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Scurvy
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Vit C, required for collagen synthesis
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Osteopenia
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inadequate ossification; reduction in bone mass,
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Osteoporosis
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Severe osteopenia that alters daily living
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Trauma
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1) Fracture hematoma
2) Internal external callus forms 3) Spongy bone fills external callus (cast removed) 4) Spongy bone replaced w/compact bone |
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Sarcolema
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Cell membrane of a muscle fiber
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Sarcoplasm
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Cytoplasm of a muscle fiber
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Sarcoplasmic Reticulum
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Forms tubular complex around each myofibril, holds calcium for muscle contraction
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Transverse tubules
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Narrow tubes that are continuous with the sarcolemma and extend into the sarcoplasm at right angles to cell surface
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Myofibrils
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cylindrical structures that run the length of a muscle fiber (>100/cell), allow a muscle to contract
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Thin Filaments
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Composed of mainly actin
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Thick Filaments
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Composed of mainly myosin
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Sarcomere
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Repeating units of myosin/actin (thick/thin filaments), smallest functional unit of muscle cell, ~10,000 sarcomeres per myofibril
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Sliding Filament Theory
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Thin filaments slide inwards toward thick filament and muscle contracts
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Epimysium
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Entire muscle surrounded by this layer, separates muscle from surrounding tissue and organs
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Perimysium
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Divides skeletal muscle into fascicles
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Endomysium
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Surround individual muscle cells or fibers
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Nerves
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axons enter the endomysium to innervate muscle fibers
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Motor Unit
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Motor neuron and all the fibers it innervates
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Fine control
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(Eye muscle) 4-6 muscle fibers innervated by one motor neuron
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Gross control
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(Quadriceps) >1000 muscle fibers innervated by one motor neuron. When the motor neuron is stimulated, one big muscle contracts
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Functions of Skeletal Muscle
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1) Produce movement
2) Maintain posture and body position 3)Support soft tissues 4) Guard entrances/exits 5) Maintain body temperature 6) Store nutrient reserves |
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Cachexia
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Tissue wasting occurs within chronic diseases
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Sarcopenia
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Muscle atrophy that occurs with aging
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Rhabdomyolosis
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Rapid skeletal muscle breakdown, can cause kidney damage
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Neuromuscular Junction
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Intercellular connection between motor neuron and muscle fiber
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Synaptic Cleft
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Space between the motor neuron and the muscle fiber
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Motor End Plate
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Region on the sarcolemma of the muscle that receives neurotransmitter
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Stimulation of a Muscle Fiber
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i. Arrival of action potential
ii. Release of Ach iii. Ach binds at motor end plate iv. Action potential spreads along sarcolemma and T-Tubercles v. Return to baseline (Ach is degraded by acetylcholinestrase) |
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Excitation Contraction Coupling
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Link between generation of an action potential in the sarcolemma and the start of muscle contraction
i. Action potential along sarcolemma triggers release of calcium from sarcoplasmic reticulum ii. Calcium binds to troponin; which moves the entire troponin-tropomysoin complex iii. Myosin head binds to active site on actin, forming a cross bridge iv. Mysoin-Actin crossbridge then move toward the center of the sarcomere; called a powerstroke v. Atp is now needed to release myosin from the crossbridge and to re-pivot the myosin for another powerstroke vi. Repeats until calcium of ATP run out |
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Rigor Mortis
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Atp no longer available after death to re-pivot myosin, stays contracted; Ca released into sarcoplasm and stays since ATP is no longer available to pump Ca back into SR causing continuous contraction
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Length-Tension Relationship
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Sarcomere has an optional optimal length
Too short: sarcomere cannot shorten anymore Too long: reduces the zone of overlap between myosin and actin, decreasing the number of possible crossbridge interactions |
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Twitch Summation
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Repeating twitches, occurs when full relaxation does not occur
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Pathophysiology
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Tetanus pathogen, no inhibition of motor neuron, constant contractions
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Recruitment
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i. smaller motor neuron activated first, typically the fiber itself contracts slower
ii. larger motor neuron activated later (with more excitation/stimulations) faster and more powerful muscles iii. To maintain constant tension at the muscle a certain # of fibers are always contracted, but they take "breaks" so some are contracted while others are relaxed, but overall the same # of fibers are contracted at any given timeframe to maintain the tension |
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Fast Fibers
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Large diameter, densly packed myofibrils, few mitochondria, large glycogen reserves
Easily fatigued White in color Glycolytic (doesn't require oxygen to synthesize ATP) Type II B EDL is primarily composed of II B Used only in quick bouts Sprinters have more fast fibers |
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Slow Fibers
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Smaller diameter, longer to reach peak tension, more capillaries
Slower to fatigue Red in color from myoglobin Dark meat of poultry are the legs Oxidative (requires oxygen to synthesize larger amounts of ATP) Type I Soleus is primarily composed of type I Marathon runners have more slow fibers |
