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EK Bio 8
muscle, bone, and skin
| Question | Answer |
|---|---|
| three types of muscle tissue | skeletal, cardiac, and smooth |
| four functions of muscle | body movement, stabilization of body position, movement of substances through the body, generating heat to maintain body temperature |
| characteristics of skeletal muscle | voluntary (consciously controlled), connects one bone to another, striated (composed of sarcomeres); multinucleate; don't generally undergo mitosis to create new muscle cells but grows by hypertrophy |
| characteristics of heart muscle | involuntary, striated, contains only 1 nucleus, and separated from its neighboring cells with intercalated disc; grows by hypertrophy |
| sarcomere | smallest functional unit of skeletal muscle, composed of many strands of thick and thin filaments, laid side by side to form myofibril |
| sarcoplasmic reticulum | specialized ER of the muscle cell that surrounds each myofibril; its lumen is filled with calcium ions |
| myosin | protein that makes up the thick filament |
| actin | globular protein that makes up the thin filament |
| 1st stage of skeletal muscle contraction | tropomyosin covers an active site on acti preventing myosin from binding (it remains in cocked high energy position with phosphate and ADP group attached) |
| 2nd stage of skeletal muscle contraction | in presence of Ca2+, troponin pulls tropomyosin back exposing the active site so myosin head can bind to actin |
| 3rd stage of skeletal muscle contraction | myosin head expels phosphate and ADP and bends into low energy position while dragging actin along with it (power stroke) --> SARCOMERE SHORTENS -- MUSCLE CONTRACTION |
| 4th stage of skeletal muscle contraction | ATP attaches to myosin head so myosin releases from active site (which is immediately covered by tropomyosin) |
| 5th stage of skeletal muscle contraction | ATP splits into inorganic phosphate and ADP causing myosin head to cock into high energy position |
| muscle contraction begins with ____ | action potential when neuron releases acetylcholine into synaptic cleft thereby activating ion channel in sarcolemna |
| t-tubules | small tunnels in muscle membrane that allow uniform contraction of muscle by allowing action potential to spread thru the muscle cell more rapidly |
| what happens to calcium at the end of 5 stage muscle contraction cycle? | actively pumped back into sarcoplasmic reticulum |
| motor unit | neuron and the muscle fibers that innervate it; independent of each other; usually smaller ones are recruited first, then larger; intricate movements have smaller motor units and those requiring greater force have large motor units |
| myoglobin | oxygen storing protein similar to hemoglobin but only has 1 protein subunit, found in type I or slow-twitch muscle fibers, make muscles have redder color |
| intercalated disc | contain gap junctions which allow action potential to spread from 1 cardiac cell to the next via electrical synapse |
| hypertrophy | increase in muscle cell diameter and change in muscle conformation |
| what is special about the action potential of cardiac muscle? | they exhibit plateau after depolarization (plateau from slow voltage-gated Ca2+ channels that allow Ca to enter and hold the inside of the membrane at (+) potential distance) which will lengthen the time of contraction |
| characteristics of smooth muscle | involuntary and innervated by autonomic nervous system, contain thick and thin filaments (not organized into sarcomeres), contain intermediate filaments attached to dense bodies |
| two types of smooth muscle | single unit and multi-unit |
| single unit smooth muscle | aka visceral, most common smooth muscle type, connected by gap junctions spreading the AP from single neuron thru a large group of cells so they act as a single unit, found in small arteries and veins, stomach, intestines, uterus and urinary bladder |
| multi-unit smooth muscle | attached directly to a neuron, a group of multiunit smooth muscle cells can contract independently, found in large arteries, bronchioles, pili muscles attached to hair follicles and the iris |
| what can cause smooth muscle to contract? | neural stimulus, hormones, changes in pH, O2, CO2, temperature, and ion concentrations |
| bone | living tissue which supports soft tissue, protects inner organs, assists in body movement, mineral storage, blood cell production, and energy storage (in the form of adipose) |
| osteoprogenitor | differentiate into osteoblasts |
| osteoblast | secrete collagen and organic cmpds upon which bone is formed, incapable of mitosis; release matrix materials to surround themselves and will differentiate into osteocytes |
| osteocytes | incapable of mitosis, exchange nutrients and waste materials with the blood |
| osteoclast | resorbs bone, releasing minerals back into the blood |
| typical long bone | epiphysis - metaphysis - diaphysis - metaphysis - epiphysis |
| spongy bone | contain red bone marrow, the site of hemopoiesis |
| compact bone | surrounds medullary cavity which holds the yellow bone marrow; highly organized; contains haversion system (osteons) |
| yellow bone marrow | storage of fat cells (adipose) |
| Haversion canals | tunnels in compact burrowed by osteoclasts then the osteoblasts lay down new matrix to form concentric rings (lamellae); contain blood and lymph vessels |
| canaliculi | how trapped osteocytes between lamallae exchange nutrients |
| volkmann's canals | crossing canals that connect the blood and lymph vessels of the Haversion canals |
| Ca2+ is stored in the body mostly in... | the bone matrix as hydroxyapatite |
| hydroxypatite | calcium phosphate hydroxyl containing compound that lies alongside collagen fibers to give bone greater compressive strength than the best reinforced concrete |
| what are the four types of bone? | long, short, flat, or irregular |
| cartilage | flexible resilient connective tissue composed primarily of collagen and has great tensile strength, contains no blood vessels, types include: hyaline, fibrocartilage, and elastic |
| three types of joints are.. | fibrous (ex skull), cartilagenous (ex: btw ribs), and synovial (wide range of movement) |
| 7 functions of skin | 1. thermoregulation 2. protection 3. environmental sensory input 4. excretion 5. immunity 6. blood reservoir 7. vitamin D synthesis |
| epidermis | avascular epithelial tissue; consists of keratinocytes, melanocytes, langerhans cells, and merkel cells; have 5 layers w/ keritnocytes pushed to top |
| dermis | connective tissue derived from mesodermal cells; embedded by blood vessels, nerves, glands, and hair follicles; contains collagen and elastic fibers to provide strength, extensibility, and elasticity |
| subcutaneous layer of skin | under the dermis that is an important heat insulator (fat maintains normal core body temp while skin approaches temp of environment) |
Created by:
miniangel918
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