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76 Cards in this Set
- Front
- Back
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During intramembranous ossification, which type of tissue is replaced by bone?
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mesenchymal or fibrous connective tissue
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In endochondral ossification, what is the original source of osteoblasts?
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The cells of the inner layer of the perichondrium differentiate into osteoblasts.
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How could x-rays of the femur be used to determine if a person has reached full height?
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If the epiphyseal lines are completely made of bone and there is no cartilage line, full growth has been reached.
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What are the sections of a long bone?
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Epiphysis (end)... then metaphysis... then diaphysis (shaft)
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Why would a weight lifter have larger bones than a runner?
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Muscles put stress on bone and it gets bigger
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Why is a child entering puberty late usually taller?
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They are taller before they hit puberty, so after the growth spurt they are taller overall.
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Increased levels of GH before puberty does what?
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Make the bones grow more, so the person will be taller
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Why does a child with rickets have trouble walking?
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They have soft bones, usually makes them bow-legged.
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What does PTH do to blood calcium levels?
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Increases them by stimulating osteoclasts, increasing intestinal absorption of calcium, and decreasing kidney excretion of calcium
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What does calcitonin do to blood calcium levels?
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Lowers blood calcium, inhibits osteoclast activity, increases kidney excretion of calcium
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At which point in fracture repair do you find an external callus?
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Early, when cells from the endosteum and periosteum migrate to the area
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Why do women have a higher chance of getting osteoporosis?
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Lower estrogen levels make replacing calcium in the bones harder
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The 2 types of bone marrow are...
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red (blood cell formation) and yellow (lipid storage)
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What mineral makes up 2/3 of bone?
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calcium phosphate interacts with calcium hydroxide to form hydroxyapatite crystals
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A bone is covered by the __ and lined by the __.
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periosteum, endosteum
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What is the basic functional unit of compact bone?
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the osteon
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Which hormones coordinate the storage, absorption, and excretion of calcium?
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calcitonin and parathyroid hormone
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Loss of bone because of aging.
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osteopenia
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What are the 4 cell populations of osseuous tissue?
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osteoblasts, osteoclasts, osteoprogenitor cells, osteocytes
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What are the primary parts of a typical long bone?
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diaphysis (shaft)
epiphysis epiphyseal cartilages/lines articular cartilage medullary canal periosteum endosteum |
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What are the components of bone matrix?
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Collagen-organic
Hydroxyapatite crystals- inorganic |
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Which organs/tissues control calcium ion concentration?
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bones, kidneys, intestinal tract
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Why does inactivity harm bones?
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It causes removal of calcium salts and bone weakening
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How do the digestive and urinary system interact with the skeletal system?
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They provide calcium and phosphate minerals for the bones, in return the bones store the minerals and protect the organs
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The connective tissue coverings of a skeletal muscle, from superficial to deep...
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epimysium, perimysium, endomysium
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The command to contract is distributed into the muscle by
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transverse tubules
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The detachment of myosin cross-bridges is triggered by
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the attachment of ATP to myosin heads
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A muscle producing almost peak tension during rapid cycles of contraction and relaxation is said to be in
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incomplete tetanus
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The type of contraction in which the tension rises, but the resistance does not move, is
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an isometric contraction
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Which of the following statements about myofibrils is not correct?
a. each skeletal muscle fiber contains hundreds to thousands of myofibrils b. myofibrils contain repeating units called sarcomeres c. myofibrils extend the length of a skeletal muscle fiber d. filaments consist of bundles of myofibrils e. myofibrils are attached to the cell membrane at both ends of a muscle fiber |
filaments consist of bundles of myofibrils
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An action potential can travel quickly from 1 cell to another because of
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gap junctions & intercalated dics
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List the 3 types of muscle tissue
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skeletal, cardiac, smooth
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What are the 3 layers of muscular connective tissue and what do they do?
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epimysium- covers entire muscle
perimysium- covers fascicle endomysium- covers single muscle fiber |
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The __ contains vesicles filled with acetylcholine
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synaptic terminal
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What 5 interlocking steps are involved in the contraction process?
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1. exposure of active sites
2. attachment of cross-bridges 3. pivoting of myosin head (power stroke) 4. detachment of cross-bridges 5. activation of myosin heads (cocking) |
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What 2 factors affect the amount of tension produced when a skeletal muscle contracts?
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1. the frequency of motor unit stimulation
2. the number of motor units involved |
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What forms of energy reserves do resting skeletal muscle fibers contain?
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ATP, creatine phosphate, & glycogen
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What 2 mechanisms are used to generate ATP from glucose in muscle cells?
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aerobic metabolism & glycolysis
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Areas you would not expect to find slow twitch muscle fibers
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eye and hand
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During relaxation muscles return to original length because of
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-contraction of opposing muscles
-pull of gravity -elastic nature of the sarcolemma -elastic forces |
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According to the length-tension relationship
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-the greater the zone of overlap in the sarcomere the greater the tension the muscle can develop
-there is an optimum range of actin and myosin ovrelap that will produce the greatest amount of tension |
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Describe the action on a myogram as tension is developed in a stimulated muscle fiber during a twitch
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1. latent period- after stimulus but before tension, action potential in muscle is generated and calcium is released from the SR
2. contraction phase- calcium binds to troponin, cross-bridges form, tension increases 3. relaxation phase- tension drops as cross-bridges detach because calcium levels fall, active sites covered again by troponin-tropomyosin complex |
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What 3 processes are involved in repaying the oxygen debt during a muscle's recovery period?
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1. o2 for aerobic respiration is consumed by liver cells, which make a lot of ATP to convert lactic acid to glucose
2. o2 for aerobic respiration is consumed by skeletal muscle fibers as they restore ATP, cp, and glycogen concentrations to their former levels 3. The normal o2 concentration in blood and peripheral tissues is replenished |
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How does cardiac muscle tissue contract without neural stimulation? What's this property called?
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automaticity
contractions are timed by pacemaker cells, specialized cardiac muscle fibers |
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A drug blocks ACh binding. Give an example of a site that such binding normally occurs, and predict the physiological effect of this drug.
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At the motor end plates of the neuromuscular junctions, the blocking would inhibit the contraction of the muscle. The muscle would remain relaxed.
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Explain rigor mortis.
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Dead cell membranes aren't permeable. SR can't retain calcium. Calcium enters sarcoplasm and sustained contraction develops. Muscles lock because there is no more ATP to detach the cross-bridges.
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What is an example of an isometric activity? An isotonic activity?
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maintaining an upright posture
writing, running, etc. |
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Inhaling an insecticide that interferes with acetylcholinesterase would do what?
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ACh in the synaptic cleft would not be broken down & would continue to stimulate the motor end plate causing persistent contraction (static peralysis)
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Which activity would be more likely to create an oxygen debt: swimming laps or lifting weights?
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Lifting weights because it requires a large amount of energy over a short period of time and the energy is made by anaerobic processes.
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Which type of muscle fibers would you find in leg muscles of a long-distance runner?
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They would most likely have a higher percentage of slow muscle fibers because they are more suited to endurance activities. Fast muscle fibers are less vascular and fatigue more quickly.
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How would a decrease in the concentration of o2 in the lungs affect the diffusion of o2 into the blood?
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The concentration gradient would decrease so the o2 would diffuse more slowly.
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During digestion in the stomach, H concentration rises to many times that of the cells of the stomach. Which transport process could be responsible?
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It would have to be active transport because the H is moving against its concentration gradient.
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If the cell membrane were freely permeable to Na, how would the transmembrane potential be affected?
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Sodium would go into the cell, so the potential would become more positive.
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How would severing a tendon attached to a muscle affect the muscle's ability to move a body part?
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It would disconnect the muscle from the bone, so if the muscle contracted nothin would happen.
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Why do skeletal muscles appear striated when viewed through a microscope?
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the z lines and thick filaments of the myofibrils are aligned
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Where would you expect the greatest concentration of Ca in resting skeletal muscle to be?
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in the cisternae of the sarcoplasmic reticulum
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How would a drug that interferes with cross-bridge formation affect muscle contraction?
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it would prevent contraction because a muscle depends on cross-bridge formation between actin and myosin to contract
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What would happen to the resting skeletal muscle if the sarcolemma suddenly became very permeable to Ca?
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greater degree of contraction and possible inability to relax because of excess Ca in the sarcoplasm
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Predict what would happen to a muscle if the motor end plate failed to produce acetylcholinesterase.
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the motor end plate would be continuously stimulated and the muscle would lock in contraction
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Why is it difficult to contract a muscle that has been overstretched?
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myosin and actin filaments would barely overlap, few cross-bridges would form, and contraction would be weak, with no overlap there would be no contraction
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Why does tension in the muscle gradually increase in treppe even though strength & frequency of stimulation stay the same?
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there isn't enough time between stimulations to reabsorb Ca, so they accumulate in higher levels in the sarcoplasm and cause more cross-bridges to form
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concentric vs. eccentric
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concentric is curling the weight up (shortens muscle), eccentric curling it back down (extends muscle)
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What feature of cardiac muscle tissue allows the heart to act as a functional syncytium?
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they are joined by gap junctions which allow ions to pass through, action potentials can spread rapidly so cells contract simultaneously
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Why are cardiac and smooth muscle contractions more affected by changes in extracellular Ca than are skeletal muscle contractions?
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because in cardiac and smooth muscles, most of the Ca ions that trigger a contraction come from extracellular fluid instead of the SR
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Smooth muscle can contract over a wider range of resting lengths than skeletal muscle can. Why?
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actin & myosin filaments are not as rigidly organized
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What effect would decreasing the concentration of extracellular potassium ions have on the transmembrane potential of a neuron?
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more potassium ions would leave the cell, so the transmembrane potential would increase (hyperpolarization)
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In a resting transmembrane potential, the inside of the cell is ___ and the exterior is ___
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slightly negative, slightly positive
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Diffusion is important in body fluids because it tends to
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eliminate local concentration gradients
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The sodium-potassium exchange pump
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is composed of a carrier protein located in the cell membrane
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When a sodium ion is moved across the cell membrane against its concentration gradient
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cellular ATP is used
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A molecule that blocks the ion channels in integral proteins in the cell membrane would interfere with
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the ability of the cell membrane to depolarize
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Explain facilitated diffusion
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Requires a carrier molecule but not cellular energy. Energy is provided by the concentration gradient of the substance being transported. When all carriers are busy, the rate of transport reaches a saturation point.
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The primary determinant of the resting membrane potential is
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the membrane permeability to potassium
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Receptors that bind ACh a the postsynaptic membrane are
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chemically regulated channels
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If the resting membrane potential is -70 and the threshold is -55, a -60 potential will
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make it easier to produce an action potential
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Describe the steps involved in the generation of an action potential.
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1-membrane depolarizes to threshold
2-voltage-regulated Na channels activated, membrane depolarizes 3-Na channels inactivated, K channels activated 4-normal permeability returns 5-voltage-regulated Na activated when repolarization is complete, voltage-regulated potassium channels close as the potential reaches normal |
