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Anatomy & Physiology > Chapter 9 Muscles > Flashcards

Chapter 9 Muscles Flashcards

1
Q

What does myo, sarco, pathy, hyper, trophy, a mean?

What is sarcolemma, sarcoplasm, sarcoplasmic reticulum***, hypertrophic, atrophy?

A
  • myo/sarco = muscle
  • patho = pathology (disease)
  • hyper = more
  • trophy = production
  • a = no
  • sarcolemma = muscle membrane
  • sarcoplasm = muscle cytoplasm
  • sacroplasmic reticulum = muscle ER
  • hypertrophic = muscle production, increase in numbers
  • atrophy = muscle decrease in size because don’t use them
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2
Q

What are the 4 special characteristics of the muscle tissue?

A
  1. excitability: ability to receive and respond to stimuli
  2. contractibility: ability to shorten when stimulated
  3. extensibility: ability to be stretched
  4. elasticity: ability to recoil resting length
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3
Q

What are the 4 functions of the muscle tissue?

A
  1. movement of bones or fluids such as blood
  2. maintaining posture and body position
  3. stabilizing joints
  4. heat generation
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4
Q

What are the 2 ways muscles attach? Through what?

A
  1. directly - epimysium fused to periosteum

2. indirectly - by CT tendon or CT aponeurosis

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5
Q

Origin is _____ bone, insertion is _____ bone. What is their relationship with each other?

A

immovable, moveable

movable (insertions) always move towards immovable (origin)

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6
Q

What is the hierarchy of muscle tissue?

A

fasicle > muscle fibers > myofibril > myofilaments > actin/myosin

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7
Q

Descriptions of a skeletal muscle fiber.

What is its shape (2)? What is the cytoplasm called? How many & what kind of nuclei does it contain? How many mitochondria do they contain? Why? What is used for glycogen storage? What is used for O2 storage? Why do muscle fibers look pink? The fiber breaks down into rod-like _____. _____ conducts impulses deep into muscle fiber. _____ ***surrounds each myofibril and forms a network of _____ that _____ (function).

A
  • long, cylindrical
  • sarcoplasm
  • multiple peripheral nuclei
  • many mitochondria because need lots of energy to move
  • glycosome for glycogen storage
  • myoglobin (protein): it is a hemoglobin in muscle, which makes it look pink
  • myofibrils
  • T (transverse) tubules
  • network of smooth ER surrounds each myofibril form pairs of lateral cisternae (end sacs) that stores & releases Ca++
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8
Q

What is the contractile unit? How many of it is in each myofibril

A

sarcomere, many many

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9
Q

What is in a sarcomere? What do their arrangement create? What makes it dark? What makes it light? What is the mechanism of muscle contraction?*** (2)

A
  • thick myosin, think actin myofilaments (contractile proteins)
  • striations
  • dark = thick myosin
  • light = thin actin
  • myosin head binds to actin, detatch, bind again
  • sarcomere shortens, muscle cell shorten, and whole muscle shortens
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10
Q

KNOW

What are the 2 contractile proteins? The 2 regulatory proteins?

Thick myosin has how many binding sites? Binding sites for what?

Thin actin
What do the actin subunits have? What covers them?*** What holds it in place? To move _____ you have to move _____. What removes the tropomyosin from the active site?

A
  • actin & myosin
  • tropomyosin & troponin

-2, one for ATP and other actin-binding site

  • active sites for myosin attachment
  • tropomyosin covers and blocks the active sites
  • troponin makes sure tropomyosin covers the active sites
  • to move the tropomyosin, have to move the troponin
  • Ca removes tropomyosin from active site by binding to troponin
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11
Q

***The neuromuscular junction. (7)

Where are the ligand-gated Na channels?
Where are the voltage-gated Na channels?
What is graded potential called in muscles?
What enzyme terminates the effect of ACH?

A
  • graded potential occurs in the dendrites, which has ligand-gated (Na) channels. this is where graded potential occurs
  • at the axon hillock, voltage-gated Na channels open
  • the AP travels down the axon to the synaptic knob
  • there, voltage-gated Ca channel open and Ca enters axon terminal
  • Ca trigger the release of ACH into the synaptic cleft by exocytosis
  • then, the ACH binds to the ligand gated Na channels on the motor end plate to allow the influx of Na into the end plate (K goes out)
  • this is a local change also called graded potential (graded potential also called the end plate potential); this entire process is called depolarization
  • ACH effects terminated by breakdown from acetylcholinesterase
  • thus, the muscle has been excited

(the AP is propagated, then repolarization occurs as Na channels close and potassium channels open)

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12
Q

What are the 3 requirements of skeletal muscle contraction?

A
  1. activation/action potential/excitation
  2. excitation-contraction coupling (brief rise in intracellular Ca)
  3. cross-bridge formation (sliding A & M - myosin pulling actin) due to Ca and ATP
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13
Q

Objective

What are the characteristics of skeletal (5), smooth (4), cardiac muscle (3) tissues?

A
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14
Q

Objective (not much time)

Difference between a tendon and an aponeurosis is that

A 
tendon = CT at end of muscle attaches to bone
aponeurosis = CT connnects muscle to muscle
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15
Q

Objective

What are the major parts of a skeletal muscle? (7) What are they?

A
  1. sarcolemma - plasma membrane
  2. sarcoplasm - cytoplasm
  3. myofibrils
  4. myofilaments - actin & myosin
  5. z discs - where thin myosin attaches
  6. sarcomere - region between z discs
  7. transverse tubules - invagination of the sarcolemm
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16
Q

Objective

What is the function of T-tubules?

A

conduct AP deep into muscle fiber

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17
Q

What makes up the triad? What is its function? What is the “code” for gates to open?

A
  • T tubules + 2 lateral cisternae of smooth ER/sarcoplasmic reticulum
  • store and release Ca++
  • AP trigger opening of voltage-gated Ca channels
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18
Q

Objective

Why does a muscle fiber need many mitochondria, plenty of myoglobin and glycosomes?

Oxygen is needed for***

A
  • skeletal muscles use energy to move so needs lots of mitochondria
  • Glucose is stored as glycogen in the liver by glycosomes
  • O2 is stored in myoglobin which is needed for the formation of ATP
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19
Q

Objective

What is a motor unit? (2) What do ***small motor units and large motor units control? What do motor neurons connect?

A
  • nerve-muscle functional unit
  • a motor neuron with all muscle fibers it supplies (can be couple or hundreds)
  • small = fine movement of fingers, eyes
  • large = large, weight bearing muscle

-connect brain to muscle

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20
Q

Objective

Know anatomy of neuromuscular junction (NMJ) and steps in order, of muscle contraction from point of action potential (AP) coming down axon and causing neurotransmitter (NT) release, thru sliding of actin/myosin, to subsequent relaxation after NT is inactivated

After end plate potential occurs…

***What goes in and out with graded potential?
Excitation contraction coupling occurs when _____.

A
  1. AP arrives at the axon terminal of a motor neuron
  2. AP opens voltage gated Ca channels to allow influx of Ca into the axon terminal.
  3. Ca entery triggers releases synaptic vessicles to release acetylcholine thrugh exocytosis.
  4. Acetylcholine binds to ligand-gated Na channels on the motor end plate to allow Na in and K out to create an end plate potential. This is a local change and is called a graded potential.
  5. Acetylcholine effects are terminated by acetylcholinesterase.

After graded potential occurs…

  1. voltage-gated Na channels open to allow influx of Na inside the cell, making it positive. Depolarization and action potential has occured.
  2. AP travels down the T tuble and opens voltage gated Ca channels. Ca is released into the sarcoplasm. This event is called excitation contraction coupling.
  3. Ca attaches to troponin to expose the active site on the actin.
  4. Events at the cross bridge occur. Myosin head attaches to the actin. ATP also attaches to the myosin head. Phosphate is removed from ATP to make ADP and P. The energy is used by the myosin head to pull actin inward. Another ATP attaches to the myosin head and the myosin head detaches from the actin.
  5. Ca returns to the lateral cisterns.
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21
Q

Objective

What do the vesicles contain _________.

A

acetylcholine

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22
Q

Objective

What is meant by the term “voltage-gated channel”? Where would one be found in the muscle fiber?

A
  • channels open when there is a change in voltage or charge

- sarcolemma, t-tubles

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23
Q

Objective

Ligand or chemically gated channel? Where would one be found in the muscle fiber?

A
  • ligand-gated channels

- sarcolemma/junctional folds

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24
Q

Objective

The NMJ: what changes are brought about. e.g when AP travels down the axon

A

stimulates voltage-gated ca channels

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25
Q

Objective

The NMJ: What is the role of calcium in the axon Terminal.

A

stimulate the release of acetylcholine by synaptic vesicles via exocytosis

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26
Q

Objective

The NMJ: Explain the function of a neurotransmitter substance.

A

neurotransmitter (chemical stored in synaptic vessicles) when released, inhibits or excites the cell

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27
Q

Objective

What neurotransmitter is released at the NMJ?

A

acetylcholine

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28
Q

Objective

By what process is the NT released from the axonal terminal?

A

exocytosis

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29
Q

Objective

Define threshold stimulus.

A

the minimal strength of stimuli required for a muscle fiber to respond

30
Q

Objective

What is the normal ion situation in resting membrane potential?

A

High [Na] outside cell, high [K] inside cell

31
Q

Objective

What happens at the end plate and which kind of gates are stimulated and what ion enters the ICF of the muscle, DURING Depolarization.

A

during depolarization, voltage-gated Na channels open to allow Na inside the cell

32
Q

Objective

What ion exits during repolarization?

A

K

33
Q

Objectives

What inactivates and destroys the NT in the synaptic cleft?

A

acetylcholinesterase

34
Q

Objective

How does calcium get out of the sarcoplasmic reticulum (SR) and how does it get back in after contraction is over?

A
  • AP triggers the release of Ca by opening the voltage-gated Ca channels
  • gets back into SR by active transport
35
Q

Objective

What causes the muscle to relax?

A

tropomyosin blocking the actin active site

36
Q

Objective

Name the two contractile proteins

A

actin & myosin

37
Q

Objective

What are the two regulatory proteins. Which one blocks actin.

A
  • troponin and tropomyosin

- tropomyosin

38
Q

Objective

What is the role of Troponin

A

hold tropomyosin in place

39
Q

Objective

Depict the number of sites on Myosin head and what attaches to them

A

2, ATP and actin

40
Q

Objective

Explain how rigor mortis occurs and why does it end?

A

since the human is no longer alive, it is not producing the ATP needed to bind to the myosin head that allows the actin to detach and relax

41
Q

Objective

Know what specific effect each of the following has at the NMJ and whether each causes muscle spasms or paralysis - Curare

A
  • blocks ACH receptors. second cells not stimulated so no AP occurs. So cannot breath and die
  • paralysis
42
Q

***Objective

Know what specific effect each of the following has at the NMJ and whether each causes muscle spasms or paralysis - Myasthenia gravis.

A
  • shortage in Ach receptors because destroyed (autoimmune disease)
  • muscle weakness (flaccid paralysis)
43
Q

Objective

Know what specific effect each of the following has at the NMJ and whether each causes muscle spasms or paralysis - nerve gas.

A
  • inhibits acetylcholinesterase, which causes muscle to contract all the time, so cannot get O2 and dies
  • convulsions
44
Q

Objective

Know what specific effect each of the following has at the NMJ and whether each causes muscle spasms or paralysis - Botulism toxin.

A
  • blocks ACH release, which causes the muscle to not move, resulting in young and pretty looking faces
  • paralysis
45
Q

Objective

Know what specific effect each of the following has at the NMJ and whether each causes muscle spasms or paralysis - Tetanus toxin.

A
  • causes excessive ACH release
  • convulsions
  • causes lockjaw
46
Q

Objective

Know what specific effect each of the following has at the NMJ and whether each causes muscle spasms or paralysis. Chart.

A
47
Q

Objective

What is a muscle twitch? Know the 3 periods of a muscle twitch and what is happening in the fiber during each phase.

A
  • single stimulus results in a single contraction = twitch
    1. Latent period - excitation-contraction coupling
    2. Period of contraction - cross-bridge formation (tension increase)
    3. Period of relaxation - Ca reentry into the SR (tension declines to 0)
48
Q

Personal note

What is excitation-contraction coupling?

A

AP generated and Ca is released

49
Q

Objective

Predict if Wave summation is brought about by increasing the ___________________________ of stimulation.

A

frequency

50
Q

Objective

Predict Multiple motor unit summation is brought about by increasing the stimulus _____________________ .

A

intensity/voltage

51
Q

*****Objective (not much time)

What is Treppe staircase effect?

A

phenomenon in which muscle undergoes a series of twitches with complete relaxation in between, and the strength of each successive contraction increases, reaching a maximum

  • increased contraction in response to multiple stimulli of the same stregth
  • inceased contraction because increasing availability of Ca in the sarcoplasm
52
Q

Objective

Describe 3 ways muscle generates ATP besides what is already stored there. How many ATP is produced in each?

Which of the 3 ways ATP is generated generates the most ATP per glucose molecule used?

Which requires oxygen?

A
  1. phosphorylation of ADP by creatine phosphate (CP) - 1 ATP
  2. anaerobic pathway (glycolysis) - 2 ATP
  3. aerobic repiration (ETC) - 32-36 ATP

-aerobic respiration

53
Q

Objective

Which activities do ATP (from which of the 4 stores of ATP) power?

A
  1. short-duration exercise
    - ATP stored in muscle first used
    - then ATP from ADP + CP
    - then glucogen stored in muscle broken down by anaerobic respiration/glycolysis to produce 2 ATP and lactic acid
    - weight lifting: ATP stores + ADP/P
  2. prolonged duration exercise (jogging, can breathe)
    - ATP from aerobic pathway
54
Q

What causes muscle soreness in short duration exercises?

A

lactic acid

55
Q

*****Objective

How is lactic acid formed? (4)
_____ takes over when muscles exceed their ____ reserves.
_____ converted to lactic acid due to _____.
_____ diffuses out of the muscle and is taken to the _____ by blood where it changes lactic acid back to ____ but that requires _____.
During exercise, _____ not the _____ using O2 so _____ accumulates.

A
  • anaerobic respiration takes over when muscles exceed their O2 reserves
  • pyruvate converted to lactic acid due to lack of O2
  • lactic acid diffuses out of the muscle and taken to the liver by blood where liver changes lactic acid back to glucose but that requires ATP
  • during exercise, muscles and not the liver using the O2 so lactic acid accumulates
56
Q

Objective - not in lecture ppt

Define terms:
Hypertrophy
Atrophy
Oxygen debt

A
  • hypertrophy = increase in muscle cell numbers
  • atrophy = inherited muscle-destroying disease; muscle size shrinks because muscle cells not used
  • O2 debt = when do not have enough O2 while exercising which results in lactic acid formation
57
Q

Objective

Distinguish between isometric and isotonic contractions

A
  • isometric contraction = no shortening, muscle does not exceed load (object not lifted)
  • isotonic contraction = shortening, muscle tension exceeds load (object lifted)
58
Q

Objective

Distinguish between concentric and eccentric contractions and explain how each is used in body movements. Muscle contracts with greater/less force than resistance.

A

Concentric contractions

  • flexion
  • shortening occurs
  • muscles contract with greater force than resistance

Eccentric contractions

  • extension
  • lengthening occurs
  • muscles contracts with less force than resistance
59
Q

***Objective - not in lecture ppt

Distinguish between a tetanic contraction and muscle tone.

A
  • muscle tone = constant sightly contracted state is partial

- tetanic contraction

60
Q

Objective

Explain muscle tone. What does it stabilize?

A
  • constant, slightly contracted state of muscles due to spinal reflexes
  • keeps muscle firm, healthy, and ready to respond
  • stabilized joint
61
Q

Objective

Explain the disease Duchenne muscular dystrophy. It appears as a disease of which gender more frequently?

A
  • muscle atrophy due to a lack of dystrophin (protein) which causes muscles to be unstable
  • victims clumsy and fall frequently
  • inherited, sex linked, carried by females (found on X chromosomes) expressed in males
62
Q

Objective

List the 5 characteristics of Smooth muscle fibers.

A
  1. found in blood vessels & digestive tract
  2. have one nucleus
  3. elongated with tapering ends (spindle shaped)
  4. involuntary
  5. 2 layers (longitudinal and circular)
63
Q

Objective

List some basic differences between smooth and skeletal muscle? (6)

A
  1. The actin and myosin filaments are present but are thinner.
  2. endomysium only, SR less developed
  3. Ca2+ is stored in caveolae.
  4. No sarcomeres, myofibrils, or T tubules. No NMJ
  5. No troponin ; so Ca2+ binds to a protein calmodulin.
  6. Varicosities of nerve fibers store and release neurotransmitters
64
Q

Objective

Distinguish between multiunit and visceral smooth muscles.
(cell organization, where they are found, what they are stimulated by)

A

Multiunit smooth muscle

  • disorganized and occur as separate fibers
  • found in iris, walls of blood vessel
  • stimulation by motor nerve impulses

Visceral smooth muscle

  • composed of sheets
  • found in walls of hollow organs (stomach, intestine, urinary bladder, uterus)
  • stimulate each other
65
Q

Objective

Define peristalsis and explain its function.

A
  • alternating contractions & relaxations of smooth muscle layers that mix & squeeze substances
  • longitudinal & circular layer contract
66
Q

Objective

What are some special features of smooth muscle that make it good at its job of lining organs like the digestive tract?

A

special feature of smooth muscle cells: hyperplasia (can divide and increase numbers that allow the organ to get larger - like in pregnancy)

67
Q

Talked about in class

How does local and general anesthisia work?

A

local - hyper polarization by opening Cl- channels

general - block Na channels to stop AP

68
Q

Not in objectives

40% of the energy released in muscle activity is useful as _____. The remaining 60% is released as _____.

A

work, heat

69
Q

Not in objectives

Why must extra O2 must be taken after exercise? (4)

A
  • replenish O2 reserves in myoglobin
  • replace glycogen stores
  • reconvert lactic acid to pyruvate
  • resynthesize ATP and CP
70
Q

Talked about in class

What causes the iris of the eye to dilate? constrict?

A
  • dilate when the longitudinal layer contracts

- constrict when circular layer contract

71
Q

Not in objectives

What is muscular dystrophy?

A

muscles enlarge due to fat and CT deposits. muscle fibers atrophy and degenerate

72
Q

Not in objectives

What is muscle fatigue? _____ to contract though _____.
What causes muscle fatigue? (3) What causes contractures like writer cramp?

A
  • inability to contract tho receiving stimuli
    1. ionic imbalances
    2. damage to SR and interferes with Ca release
    3. lack of ATP causes contractures like writers cramp

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