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Biology > Bio 150- Muscles > Flashcards

Bio 150- Muscles Flashcards

1
Q

General functions of the muscular system

A

-Body movement
-Maintenance of posture and stability
-Support soft tissues
-Guard “entrances and exits”
-Production of body heat
-Also:
Communication
Constriction of organs and vessels
Heart beat
Storage of nutrient reserves

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2
Q

Muscle tissue: defining characteristics

A

-Able to contract (“contractility”)
Can shorten forcibly
Causes movement of attached structures, or change in volume/pressure…
(note: lengthening of muscle is passive! Muscles can only “pull”, they can’t “push”!)
-Excitable! (“excitability”)
Muscle can respond to a stimulus (from nerves, hormones…)
-Conductivity
-Extensibility (can stretch)
-Elasticity (can recoil after being stretched)

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3
Q

Skeletal muscle

A
  • Striated
  • Attached to bone
  • Cells are long and cylindrical, with many nuclei (peripherally located)
  • Under voluntary control
  • body movement
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4
Q

Smooth muscle

A
  • Not striated
  • Cells are spindle shaped, each with one central nucleus
  • Involuntary control
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5
Q

Cardiac muscle

A
  • Striated
  • Cells are cylindrical and branched, each with one, central nucleus
  • *intercalated discs (with gap junctions) join neighbouring cells
  • Involuntary control
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6
Q

Skeletal muscles are made up of:

A

-Muscle fibers (cells): Number of fibers remains fairly constant after birth!
But they can increase in size

  • Connective tissue
  • (+blood vessels and nerves)
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7
Q

Muscle fiber

A

-Each muscle fiber (cell) is surrounded by sarcolemma (the cell’s plasma membrane)
-Sarcoplasm: cytoplasm
-Each fiber is surrounded by endomysium (CT)
-T tubules:
Invaginations of the sarcolemma
-Sarcoplasmic reticulum (SR):
Specialized smooth ER
-Triad:
T-tubules
Terminal cisterna (enlargement of SR near T tubules)

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8
Q

A bundle of fibers (and their endomysium) are surrounded by perimysium
This is called a

A

fascicle

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9
Q

Many fascicles are grouped together, and surrounded by

A

epimysium (dense CT)

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10
Q

CT layers form

A

tendon/ aponeurosis

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11
Q

Epimysium =

A

fascia

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12
Q

Nerve and blood supply to muscle

A
  • An axon (of a motor neuron), an artery, and a vein tend to travel together through the CT layers
  • Each axon branches so that each muscle fiber (=cell) receives a branch of an axon
  • Arteries branch to form capillary beds (supply muscle tissue with O2, glucose, etc.)
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13
Q

Muscle fiber microstructure :Most of the cell is filled with

A

myofibrils

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14
Q

Each myofibril goes the length of the cell, and is made up of 2 main different protein filaments:

A

actin (thin) and myosin (thick)!

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15
Q

two myofilaments (actin and myosin, plus a 3rd called titin) form the

A

sarcomeres

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16
Q

The actin myofilaments are anchored by the

A

Z-disk

17
Q

The myosin myofilaments are held in place by the titin filaments, and in the middle of the

A

H band

18
Q

A sarcomere extends from

A

one Z-disk to the next Z-disk

19
Q

I band

A

(isotropic, l-I-ght band)

Includes Z-disk; between the myosin myofilaments

20
Q

A band

A

(anisotropic, d-A-rk band)

Extends the length of the myosin filaments

21
Q

H zone

A

In the middle of the A band; only myosin (no actin)

22
Q

Actin (thin) myofilaments

A
  • Two strands of F actin (fibrous actin), plus tropomyosin and troponin molecules
  • F actin is actually a chain of G actin molecules (globular)
  • Allows for attachment of myosin heads!
23
Q

Myosin myofilaments

A

-Each myosin myofilament is made up of many myosin molecules
Each one looks like a golf club!
-Rod portion + head
-The heads form cross-bridges with the actin

24
Q

Titin myofilaments

A
  • Very elastic
  • Anchors myosin to the Z-disc
  • Keeps actin and myosin in alignment
  • Helps the muscle to resist extreme stretching
25
Q

Origin:

A

the “fixed end”.

26
Q

Belly:

A

thick midregion of the muscle.

27
Q

Insertion:

A

the “moveable end”. Muscle contraction pulls the insertion point closer to the origin.

28
Q

Agonist:

A

the “prime mover”

29
Q

Synergist:

A

helps the agonist (e.g., stabilize?)

synergist is usually smaller than the agonist

30
Q

Antagonist:

A

opposes the action of the agonist

31
Q

Fixator:

A

prevents a bone from moving

32
Q

Types of movements – Angular movements

A

Flexion
Extension
(Hyperextension)

Abduction
Adduction

Circumduction

33
Q

Types of movements – Rotational movements

A

Lateral (external) rotation
Medial (internal) rotation
Right and left rotation

Pronation
Supination

34
Q

Types of movements – Special movements

A 
Eversion
Inversion
Dorsiflexion
Plantar flexion
Opposition
Protraction
Retraction
Depression
Elevation
Lateral flexion

Biology (12 decks)

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