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BIO 240 Anatomy and Physiology I > Ch 10 Muscular System > Flashcards

Ch 10 Muscular System Flashcards

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1
Q

What is the PRIME function of muscle?

A

Convert chemical energy (ATP) into mechanical energy in order to:

  1. generate force
  2. perform work
  3. produce movements
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2
Q

What are the types of muscle tissue?

A

Skeletal Muscle

  • striated
  • voluntary
  • stimulated by nervous system only

Cardiac Muscle

  • striated
  • involuntary
  • stimulated/inhibited by nervous/endocrine system

Smooth Muscle

  • non-striated
  • involuntary
  • stimulated/inhibited by nervous/endocrine system
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3
Q

What are the 5 characteristics of muscle tissue?

A
  1. Excitability - stimulated by signal
  2. Conductivity - membrane carries elec signal
  3. Contractility - shortens
  4. Extensibility - Lengthens
  5. Elasticity - returns to orig shape
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4
Q

What are the 3 GENERAL functions of muscle tissue?

A
  1. Motion
  2. Stabilizing body positions and regulation of organ volume, ie sphincter
  3. Thermogenesis
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5
Q

What are the types of fascia?

A

Superficial fascia - hypodermis

Deep fascia - fibrous connective tissue that allows muscle to ove past eachother w/o friction

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6
Q

What are the connective tissues of skeletal muscles?

A

Epimysium - out layer surrounds entire muscle

Perimysium - surrounds fascicles

Endomysium - surrounds individual muscle cells (fibers). provides insultation to excite one cell but not another.

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7
Q

What is a tendon? What is a tendon sheath? What is aponeurosis?

A

Tendon - the three types of connective tissue that connect muscle to bone

Tendon sheath - band that surrounds tendons to reduce friction w/ synovial membrane

Aponeurosis - tendon that forms a flat sheet instead of cord

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8
Q

What are the following:

  • myofiber
  • sarcolemma
  • sarcoplasm
  • myofibrils
  • myofilaments
  • sarcomeres
A

myofiber - muscle cell

sarcolemma - cell membrane of muscle cell

sarcoplasm - cytoplasm of muscle cell

myofibrils - bundle of myofilaments

myofilaments - actin+myosin

sarcomeres - function unit of muscle that contracts/extends

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9
Q

What is a sarcomere?

A

The functional unit of the muscle within myofibrils composed of thin actin and thick myosin fliaments

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10
Q

Name the segments of the sarcomere pictured.

A
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11
Q

Go over the anatomy of the thin myofilament. What is the purpose of the interaction of all the different parts of this myofilament?

A

Each actin molecule on the strand of actin filament has a myosin-binding site

  • at rest this binding site is hidden to prevent binding which will cause contraction
  • the tropomyosin-troponin complex covers these binding sites
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12
Q

What are the parts of the thick myofilament pictured?

A
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13
Q

What is the sarcoplasmic reticulum?

A

Intracellular tubules wrapping the myofibrils

  • stores Ca2+​ ions at rest
  • releases Ca2+​ ions into sarcoplasm when stimulated causing tropmyosin-troponin complex to release myosin binding sits on thin actin myofilaments
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14
Q

What are the transverse tubules?

A

Tunneled extension of the sarcolemma perpendicular to the myofibrils in between the terminal cisternae

-carries electrical signal from the sarcolemma to signal the sarcoplasmic reticulum to open Ca2+ channel

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15
Q

What is a motor unit? What is recruitment?

A

1 Motor Neuron + ALL of the muscle cells it innervates

  • small motor units for precise movements
  • large motor units for gross movements

Recruitment is how many motor units you are activating

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16
Q

Name the components of the neuromuscular junction pictured. What oes each of the following component do

Axon terminals

Synapse and synaptic cleft

Motor end plate

Synaptic vesicles

Neurotransmitter = acetylcholine (ACh)

ACh receptors on motor end plate

A

Axon terminals - end of the neuron that holds synaptic vesicles

Synapse and synaptic cleft - releases neurotransmitter into cleft where it is uptaked by receptors

Motor end plate - part of muscle cell interacting w/ neuron ridged for more surface area

Synaptic vesicles - hold neurotransmitters

Neurotransmitter = acetylcholine (ACh) - activates muscle cell

ACh receptors on motor end plate - bind the ACh

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17
Q

How does the neuromuscular junction work?

A
  1. Nerve impulse travels down membrane of neuron causing neuron Ca2+ channels to open
  2. Synaptic vesicles rupture into synapse
  3. ACh diffuses to receptors on motor end plate
  4. ACh binding to receptors starts impulse in sarcolemma by opening Na+ channels causing voltage change
  5. The voltage change travels along sarcolemma and down T-Tubules causing voltage change in sarcoplasmic reticulum
  6. Voltage change in sarcoplasmic reticulum causes Ca2+ channels to open and remove tropomyosin-troponin from myosin binding sites on actin
18
Q

How does the sliding filament theory work for excitation-contraction coupling?

A

Cross bridges attach to binding sites on thin myofilaments

  • The cross bridges tilt
  • Thin myofilaments slide across thick myofilaments shortening sarcomeres
19
Q

What is the power stroke?

A

Power stroke is the muscle contraction

  • Ca2+ channels in sarcoplasmic reticulum open and bind topomyosin-troponin complex and activate ATPase
  • Cross bridges bind and swivel
20
Q

What is the recovery stroke?

A

Muscle relaxation

  • ACh removed from synapse
  • Ca2+ pumped back to sarcoplasmic reticulum
  • W/ no Ca2+ tropomyosin-troponin complex covers myosin binding sites
  • W/ no Ca2+ myosin cross bridges release and thin myofilaments slide back to resting position
21
Q

Go through excitation-contraction coupling from beginning to end muthafucka.

A
  1. Arrival of nerve impulse at axon terminal of motor neuron
  2. Acetylcholine released
  3. Acetylcholine binds to receptors on motor end plate
  4. Electrical message created in sarcolemma
  5. It travels down T-tubules and throughout sarcoplasmic reticulum
  6. Ca++ released over the myofibrils
  7. Ca++ binds to troponin; tropomyosin-troponin complex shifts to expose binding sites
  8. Energy from ATP activates and “cocks” myosin cross bridges
  9. Cross bridges attach to binding sites on actin molecules
  10. Power stroke; thin myofilaments “slide” over thick myofilaments
  11. Binding of new ATP, breaking cross bridge; repeat steps 9 – 10
  12. Cessation of nerve impulse and ACh release at motor neuron
  13. Acetylcholinase breaks down ACh
  14. Ca++ actively transported back into sarcoplasmic reticulum
  15. Loss of Ca++ from sarcoplasm allows tropomyosin-troponin to block active sites on actin
  16. Thin myofilaments “slide” back across thick myofilaments into resting position
22
Q

How does sarcomere length affect contraction?

A

Muscle strength depends on how stretched/contracted the muscle is before it is stimulated

  • too contracted/stretched=too much/not enough overlap of myofilaments resulting in less force
  • there is an optimum resting length
23
Q

What is muscle tone?

A

state of partial contraction of a resting skeletal muscle

  • a few motor units are contracting while others are at rest
  • essential for maintaining posture
  • ASYNCHRONOUS FIRING of motor units (take turns)
24
Q

What enzymes are involved in providing IMMEDIATE energy to skeletal muscle?

A

Myokinase

-transfers the Pi from ADP→AMP+Pi to ADP+Pi→ATP

Creatine Kinase

-takes Pi from creatine phosphate and donates to ADP+Pi→ATP

Phosphagen system - provides all energy for short intense activity. Around 15 secs

25
Q

Once the phosphagen system is exhausted, what provides short-term energy?

A

Anaerobic Metabolism

  • switch to anaerobic metabolism once phosphagen system is exhausted b/c O2 in myoglobin is used up
  • Need ATP before Aerobic Respiration kicks in and delivers O2 to muscles
  • Anaerobic metabolism buys you time until Aerobic metabolism kicks in
  • 30-40 secs of maximum activity
26
Q

What kind of metabolism provides long term energy?

A

Cardiovascular and respiratory systems ‘‘catch up’’ after about 40 secs and start delivering sufficient oxygen so aerobic respiration meets ATP demand

27
Q

What will prevent activity once aerobic metabolism kicks in?

A

Activity will continue until loss of glycogen, blood glucose, fluids and electrolytes coupled with lactic acid buildup

-ie. fatigue

28
Q

What is oxygen debt?

A

The difference between O2 consumption at rest and the evated O2 consumption after exercise

-debt repaid to replenish O2 in myoglobin, replenish phosphagen system

29
Q

What are the types of muscle fibers?

A
  1. Slow oxidative, Slow-Twitch, Red, Type I Fibers
    - abundant in mitochondria, myoglobin and capillaries
    - aerobic respiration
    - don’t fatigue easily
  2. Fast Glycolytic, Fast-twitch, White, Type II Fibers
    - poor in mitochondria, myoglobin, and capillaries
    - Phosphagen pathways
    - Anaerobic metabolism
    - Fatigue quickly
  3. Intermediate fibers
    - characteristics of both
30
Q

Go through the controlled condition, receptor, control center, effectors and return to homeostasis for body temperature control for decrease in body temp.

A

Controlled condition - stimulus disrupts homeostasis by causing decrease in body temp

Receptor - thermoreceptors in skin send signals to hypothalamus

Control Center - hypothalamic control center sends nerve impulse to stimulate skeletal muscles

Effectors - skeletal muscles increase their tone involuntarily, ie. shiver

Return to Homeostasis - innefficient use of energy of contracting skeletal muscles generate heat and return to homeostasis

31
Q

What is the all or none principle?

A

In order to contract the neuron must meet threshold stimulus

32
Q

What kind of contraction is this and what are the phases of the contraction?

A

Twitch Contraction

  • One single contraction due to a single electrical impules
  • not sustained
33
Q

What kind of contraction is this?

A

Treppe contraction

  • staircase phenomenon
  • multiple stimuli with complete rest in between
  • force goes up with each contraction
34
Q

What are isotonic and isometric contractions?

A

Isotonic contraction

-length of muscle changes but force stays the same

Isometric contraction

-length of muscle stays the same but force changes

35
Q

What is wave summation?

A

Stimulate the muscle after the refractory period but before muscle has a chance to fully relax

-more force with 2nd twitch

36
Q

What is incomplete tetany (non-fused)?

A

some relaxation then another stimulus

  • 20-30 stim/sec
  • daily movement
37
Q

What is complete (non-fused) tetany?

A

Experimental only

  • no relaxation
  • 80-100 stim/sec
  • tetanus
38
Q

What differentiates cardiac muscle?

A

Striated

Single nucleus/cell

Intercalated discs

Functional syncytium

Involuntary

39
Q

What differentiates smooth muscle?

A

Non-striated (has actin/myosin but no sarcomeres)

Single nucleus/cell

Two types

visceral (functional syncytium) - digestive tract

multiunit - blood vessels

40
Q

How do muscle cells produce movement?

A

exert force on tendons

the tendons cross joints

the joints act as fulcrum for lever system

41
Q

What is the origin, insertion, and gaster of the muscle?

A

Origin

part of muscle with least movement

Insertion

part of muscle with most movement

Gaster

belly of muscle that bulges with flexing

42
Q

What is the agonist and antagonist for flexion of the elbow?

A

Agonist or ‘Prime Mover’ is the Biceps brachii

Antagonist is the triceps brachii

BIO 240 Anatomy and Physiology I (19 decks)

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