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Bio 239 > 5. Muscular System > Flashcards

5. Muscular System Flashcards

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Biology 101 flashcards
1
Q

What are the 3 types of muscle?

A
  1. skeletal muscle
  2. cardiac muscle
  3. smooth muscle
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2
Q

What are the characteristics of skeletal muscle?

A
  1. striated
  2. moves bones of skeleton
  3. voluntary
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3
Q

What are the characteristics of cardiac muscle?

A
  1. striated, located in heart
  2. pacemaker initiates contraction, autorhythmicity
  3. involuntary
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4
Q

What are the characteristics of smooth muscle?

A
  1. smooth or nonstriated, located in walls of hollow internal structures (blood vessels, airways, most organs in abdominopelvic cavity)
  3. involuntary
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5
Q

What are the 5 functions of muscle?

A
  1. movement
  2. stability: of body positions such as sitting or standing. Ex: sustained contractions in neck muscle hold head up
  3. communication: gestures, tongue
  4. control of body openings and passages: sustained contractions of sphincters may prevent outflow of contents of a hollow organ. Ex: esophageal, gastric, anal.. temporary storage of food in stomach, urine in bladder, smooth muscle in blood vessel walls contract and relax to regulate bloodflow
  5. heat production: muscles make heat when they contract. When you are cold, your muscles try to contract vigorously (shivering) to increase the rate of heat production
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6
Q

What are the 3 CTs and fascicles of the muscular system?

A

tendon (+periosteum) –> bell of skeletal muscle (+epimysium) –> fasciculus (+perimysium) –> muscle fiber (+endomysium) –> myofibril –> filament

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7
Q

What is endomysium?

A
  • loose CT on the inside of fascicle
  • helps bind muscle fibers together yet loose enough to allow them to freely move over one another. Carries small blood vessels that supply the fibers with nutrients.
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8
Q

What is fascicle?

A
  • muscle fiber bundles
  • muscle fibers can tear when working out, and they are not replaced (no mitosis). Hypertrophy - the muscle cells themselves get bigger by filling with protein
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9
Q

What are fascia?

A

surrounds all muscles

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10
Q

What are tendons? What are ligaments?

A
  • tendons: always attach muscle to bone
  • ligaments: dense regular CT composed of collagen and fibroblasts, attaches organs within structures and bone to bone. Ex: feet - all the bones (tarsals and metatarsals) are held together with ligaments. Ex: when you sprain your foot, you tear the ligaments.
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11
Q

What is perimysium?

A

-dense CT covering that holds the fascicles together. Can tear away if working out excessively

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12
Q

What is epimysium?

A

-thicker dense CT that binds all fasciculi together to form muscle belly. On the outside, extends to ends as fibrous band onto the tendon

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13
Q

What is superficial fascia? What is deep fascia?

A
  • superficial fascia: just beneath the skin, large CT sheets just beneath the skin that protect (grouped) skeletal muscles (like socks). Ex: fascitis - surgically open the skin to allow the expansion of infected muscles, or it will compress the blood vessels, leading to loss of the limb
  • deep fascia: deeper than superficial fascia
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14
Q

What are the 4 functional groups of muscles?

A
  1. agonist
  2. synergist
  3. antagonist and antagonistic pair
  4. fixator
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15
Q

What is the ultrastructure of muscles?

A
  1. sarcolemma
  2. sarcoplasmic reticulum
    - transverse tubules
    - terminal cisternae
    - sarcoplasm
    - calveolae
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16
Q

What is a sarcolemma?

A

(sarc = flesh, lemma = sheath) the plasma membrane of a muscle fiber. Has little holes (caveolae) like the nuclear membrane of nucleus

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17
Q

What is the sarcoplasmic reticulum (SR)?

A

fluid-filled system of membranous sacs, encircles each myofibril. Does the same thing as endoplasmic reticulum but also stores electrolytes. Contains calcium - if calcium-deficient, your muscles will get weak. No calcium, sodium, or potassium? results in shut-down of nervous system

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18
Q

What are transverse tubules (t-tubules)?

A
  • invaginations of sarcolemma filled with interstitial fluid. Tunnel in from surface toward center of each muscle fiber. Extensions of t-tubules form caveolae
  • arrangement allows superficial and deep parts of muscle fiber to be excited by an action potential almost simultaneously - calcium goes up into t-tubule and is stored in terminal cisternae so that when the message is delivered, calcium is released and the muscle can contract
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19
Q

What are terminal cisternae of SR?

A

dilated end sacs of SR that sandwiches T-tubules

20
Q

What is the sarcoplasm of SR?

A
  • cytoplasm of muscle fiber, surrounded by sarcolemma
  • has a lot of glucose for ATP, red protein myoglobin (binds oxygen and releases for ATP production by mitochondria), many myofibrils (appearance of striations)
21
Q

What are calveolae of SR?

A

little holes in sarcolemma that allow the skeletal muscle cells to take up calcium

22
Q

What are the 3 filaments in a myofibril (myofilaments) What are the 6 aspects of a sarcomere?

A
  1. thick filaments (myosin)
  2. thin filaments (actin)
  3. elastic filaments
  4. A band
  5. I band
  6. H band/zone
  7. Z disc/line
  8. M line
  9. protein titin (looks like a spring)
23
Q

What is a sarcomere?

A
  • the smallest unit of a myofibril/contraction; muscles are full of sarcomeres
  • protein fibers slide against one another, contract, and then relax
24
Q

What are the thick filaments of myofibril?

A

homogenous structure of MYOSIN

25
Q

What are the thin filaments of myofibrils?

A

not homogenous, made of 3 distinct molecules

26
Q

What are the 3 components of thin filaments?

A
  1. G-actin (globular actin, like a balloon): beads with binding sites for myosin to bind
  2. tropomyosin: thread-like, covers the binding sites on G-actin
  3. troponin: cluster of elements that controls tropomyosin –> after calcium binds to troponin, troponin will shift the tropomyosin to uncover binding sites on G-actin for myosin to bind. Muscle relaxation requires ATP to make calcium leave and detach myosin from actin.
    - angle changes - there is a configurational change when myosin binds to actin. Binding, shifting motion allows myosin to contract
27
Q

What is the A band of a sarcomere?

A

entire length of myosin or thick filament (does not change when muscle contracts)

28
Q

What is the I band of a sarcomere?

A

the distance from the end of myosin in one sarcomere to end of myosin fibers in a neighboring sarcomere; only thin filaments

29
Q

What is the H band/zone of a sarcomere?

A

distance between one thin actin filament to the other one right across (within A band), because the actin filaments are separated with myosin in between (A band); only thick filaments

30
Q

What is the Z disc/line of a sarcomere?

A

forms the boundary of a sarcomere. They are the striations

31
Q

What is the M line of a sarcomere?

A

indicates the middle of the thick filaments (middle of myosin)

32
Q

What are the characteristics of protein titin?

A

(looks like a spring) can compress and then expand, secures and stabilizes myosin (thick filament)

33
Q

When a muscle contracts, what are the changing features?

A

spaces change because the muscle contracts:
I-band and H zone disappear - the ends of the filaments come together as muscle contracts, resulting in no space between. protein titin is compressed

34
Q

When a muscle contracts, what are the unchanging features?

A

Z-disc, M-line, A band are the same

35
Q

What are the 8 somatic motor fibers of motor neurons at a neuromuscular junction?

A
  1. synapse
  2. neuromuscular junction
  3. synaptic knob/end bulbs
  4. motor end plate
  5. synaptic cleft:
  6. synaptic vesicles
  7. ACh receptors
  8. AChE
36
Q

What is a synapse?

A
  • little space/gap

- synapses can be taken away or made; body will create more synapses when you are doing something constantly

37
Q

What is a neuromuscular junction?

A

synapse between somatic motor neuron and skeletal muscle fiber

38
Q

What are the synaptic knobs/end bulbs?

A

contains synaptic vesicles

39
Q

What are the motor end plates?

A

region of sarcolemma opposite synaptic end bulbs that contain ACh receptors

40
Q

What is a synaptic cleft?

A

a small gap that separates the 2 cells

41
Q

What are synaptic vesicles?

A
  • membrane-enclosed sacs or transport structures released by synaptic buttons (synaptic buttons must take up calcium to release vesicles)
  • full of neurotransmitter acetylcholine that our muscles/skeleton use for movement, and by the brain for storing long-term memory
42
Q

What is AChE?

A

acetylcholine esterase - an enzyme that breaks down acetylcholine which ends the action potential, so that you do not get contractile spasms

43
Q

What are the 2 classes of muscle fibers?

A
  1. slow oxidative: slow-twitch, red because high myoglobin content to bind more oxygen, more mitochondria, Type I fibers. Use ATP at a slow rate –> slow speed of contraction –> resistant to fatigue. Adapted for maintaining posture and running marathons
  2. fast glycolytic: fast-twitch, white because low myoglobin content, a lot of glycogen, generate ATP by glycolysis (anaerobic), use ATP at a fast rate –> fatigue quickly. contains the most myofibrils to generate the most powerful contractions. Adapted for weight-lifting or throwing balls
44
Q

What are the 2 characteristics of cardiac muscle?

A
  1. branched fibers, single nucleus
  2. contains intercalated discs: each muscle cell of the heart has its own beat but they are physically connected to each other, and once they make contact, they can synchronize the beat. 2 pacemakers synchronize. When the synchronicity is lost, the heart goes into arrythmia. Gap junctions and desmosomes allow swift communication
45
Q

What are the 4 characteristics of smooth muscle?

A
  1. spindle-shaped (tapered at both ends), single nucleus
  2. no sarcoplasmic reticulum
  3. syncitial: contraction of smooth muscle occurs like a wave rather than all at once like skeletal muscle. Net of intermediate filaments confers the syncitial movement. Ex: uterus is made of smooth muscle, it is contracting in a wave during labor
  4. lines blood vessels
46
Q

What is a reflex arc?

A

pathway followed by nerve impulses that produces a reflex
-autonomic reflexes: responses when nerve impulses pass over an autonomic reflex arc. Regulate BP, heart rate, digestion, urination…

47
Q

What are the characteristics of a reflex arc?

A
  1. sensory receptor: distal end of sensory neuron (dendrite), respond to stimulus by generating nerve impulses
  2. somatic afferent fibers (axons) - sensory fiber/neuron: nerve impulses conduct from the sensory receptor along the axon of sensory neuron to axon terminal (in CNS gray matter)
  3. interneuron(s) - association fibers: integrating center - a single synapse between a sensory neuron and motor neuron, includes 1 or more interneurons
  4. somatic efferent fiber:
  5. effectors - skeletal muscle: body part that responds to motor nerve impulse, such as a muscle or gland

Bio 239 (21 decks)

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