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Bio 111 > Muscles > Flashcards

Muscles Flashcards

0
Q
  1. Motion
A

Movement of skeletal muscles. I.e. Walking.
Breathing and movement of body fluids.
Cardiac muscle and digestion.

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1
Q

Functions of muscles:

A
  1. Motion
  2. Heat production
  3. Posture and body support
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2
Q
  1. Heat production
A

40% of body weight is muscle and produces friction and heat with contraction.

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3
Q
  1. Posture and body support
A

The skeleton gives shape, muscles support joints and give posture.

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4
Q

3 muscle types:

A

Cardiac, skeletal, smooth

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5
Q

Properties of muscle:

A
  1. Irritability
  2. Contractility
  3. Extensibility
  4. Elasticity
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6
Q
  1. Irritability
A

Muscle tissue receives and responds to nerve stimulus

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7
Q
  1. Contractility
A

Muscle contracts due to stimulus

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8
Q
  1. Extensibility
A

Muscle contracts with stimulus. After stimulus an opposing muscle contracts and stretches the 1st muscle to it’s original length.

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9
Q
  1. Elasticity
A

Muscle can stretch and return to it’s original length

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10
Q

Muscle development:

A
  • 4 weeks after conception blocks of mesoderm (myotomes) in the trunk begin rapid mitotic division. New cells are called myoblasts.
  • Syncytial myotubule.
  • At 9 weeks primitive myofilaments appear.
  • Growth continues by adding myoblasts.
  • Quickening - fetal movement. Occurs at the 17th week or 5th month.
  • Just before birth myoblast production stops. You are born with all the muscle cells you will have. Conditioning, weight training increases size, but not the # of muscle cells.
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11
Q

Syncytial myotubule –

A

A multi nucleated mass from the union of many myoblasts

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12
Q

Connective tissues:

1. Origin -

A

The fixed end of a muscle. Usually proximal to the trunk.

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13
Q

Connective tissues:

2. Insertion -

A

The moveable end of a muscle. Usually distal to the trunk.

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14
Q

Connection tissues:

3. Belly or gastor -

A

Thickened center portion of a muscle.

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15
Q

Connective tissues:

4. Tendon -

A

Dense fibrous connective tissue which spans a joint and joins muscle to bone.
Connects to the periosteum of bone. Transfers contraction force from the muscle to the bone and causes movement.

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16
Q

Connective tissues:

5. Aponeuroses -

A

A flat sheet like tendon over broad areas. I.e. Connects frontalis to occipitalis over the top of the head.

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17
Q

Connective tissues:

6. Retinaculum -

A

Connective tissue that houses a group tendons

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18
Q

Associated Connective Tissue:

A

Arranged in muscle to protect, strengthen, and bind muscle fibers into bundles.

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19
Q

Associated Connective Tissue:

1. Endomysium -

A

Binds adjacent fibers into groups & supports nerves and capillaries

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20
Q

Associated Connective Tissue:

2. Perimysium -

A

Binds groups into bundles called fascicle

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21
Q

Associated Connective Tissue:

3. Epimysium -

A

Covers entire muscle and is continuous with a tendon

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22
Q

Associated Connective Tissue:

4. Fascia -

A

Binds separate muscles together

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23
Q

Muscle groups:

- Synergistic -

A

Muscles that work together for one function.

I.e. Biceps brachii and the brachialis muscle that work together to flex the forearm.

24
Muscle groups: | - Antagonistic -
Muscles perform different functions. | I.e. Triceps brachii which functions to extend the forearm, is antagonistic to the biceps brachii and brachialis.
25
Muscles classified by...?
Fiber arrangement.
26
1. Parallel or fusiform -
Contract over a long distance, good endurance, not necessarily strong. I.e. Sartorius - a strap like muscle over the thigh.
27
2. Convergent -
Fibers converge at the insertion to maximize contraction force. Fan shape. I.e. Deltoid or pectoralis major.
28
3. Pennate -
Many fibers per unit. Fibers arranged around one or more central tendons like the barbs of a feather. Pennate muscles shorten only to a limited extent, but they can produce very powerful actions. Strong, provides dexterity, short length, and tire quickly. I.e. Pinnate muscles in forearm, calf, or thigh.
29
4. Circular -
Surround body openings. | I.e. Orbicularis oris (mouth), oculi (eye)
30
Blood and nerve supply
Muscle has a high metabolic rate and needs food blood supply to provide O2 and remove waste & CO2. Small muscles have their own artery. Large muscles have many veins & arteries. Capillaries are in the endomysium surrounding each fiber.
31
Muscle cell -
Multi nucleated, contains the usual cell organelles & is a cylinder up to 30 cm long. Called a muscle fiber and striated (striped).
32
Sacolemma -
Cell membrane
33
Sarcoplasm -
Cytoplast
34
Sarcoplasmic reticulum -
Endoplasmic reticulum. Modified to pump Ca+ to muscle fibers.
35
Transverse tubules (T tubules)
Formed by sacrolemma. Open to the extra cellular fluid. Brings in Ca+ to the sacroplasmic reticulum.
36
Actin -
The thin filament in the muscle composed of actin monomers. | Myosin cross bridge
37
Myosin -
The thick filament of muscle composed of myosin. (Resembles golf clubs)
38
Sacromere -
Unit of contraction in muscle
39
Rigor Mortis -
All ATP binding sites are attached. No fresh supply of ATP, so myosin doesn't detach.
40
Isotonic contraction -
Force of contraction remains constant throughout the contraction.
41
Isometric contraction
Muscle length is constant. The opposing force = muscle contraction force.
43
Sliding filament theory of muscle contraction: | Myosin -
Looks like a golf club. The head of myosin will bond to 1 of 3 active sites on actin. ATP acts as the "glue" between actin and myosin.
44
Sliding filament theory of muscle contraction: | Actin -
Looks like a string of pearls. Each "pearl" monomer has has 3 active sites.
45
Sliding filament theory of muscle contraction: | Tropomyosin -
A long chain protein molecule that covers the active sites of actin and prevents contraction.
46
Sliding filament theory of muscle contraction: | Troponin -
A control protein that hold tropomyosin in place on the active sites of actin. Ca+ causes tropomyosin and troponin to roll off the active sites of actin.
47
Sliding filament theory of muscle contraction: some steps
1. Nervous stimulation releases Ca+ from the T tubules into the sarcoplasmic reticulum. 2. Ca+ bonds to troponin and rolls tropomyosin and troponin off the active site. 3. Myosin forms a cross bridge with ATP to actin. 4. ATP --> ADP + P The bond energy is used to bend the myosin head, pulling actin (a bit of contraction takes place). 5. New ATP is added. The cross bridge breaks and a new bond forms. This cycle continues until the muscle is contracted.
48
Neuromuscular junction: | Synaptic knob -
The expanded tip of the axon branch, on the sarcolemma called the motor end plate. Acetylcholine or neurotransmitter is released here & triggers Ca+ release and muscle contraction.
49
Neuromuscular junction: | Synaptic cleft -
The space that separates the synaptic knob and motor end plate.
50
Neuromuscular junction: | Motor end plate -
The end of the muscle that received the signal to contract. It also releases acetylcholinesterase to decompose acetylcholine in the cleft after the initial impulse.
51
Steps in contraction: | 1.
1. Release of ACH from synaptic knob into the synaptic cleft. ADH diffuses to motor end plate.
52
Steps in contraction: | 2.
2. Depolarization of the motor end plate. - Increases Na+ permeability. Na+ rushes in, depolarizers the membrane, and causes a (+) charge inside the muscle cell membrane. - Depolarization lasts 2-20 microseconds. - Acetylcholinesterase degrades ACH - The Sodium Potassium pump returns Na+ to the outside and the membrane is repolarized.
53
Steps in contraction: | 3.
3. Generation of action potential. Depolarization at the end plate spreads across the sarcolemma. -Excitability -Action potential
54
Excitability -
Ability to conduct electrical impulse. | -Only muscle and nerve are excitable.
55
Action potential -
Depolarization sweeps across the sarcolemma.
56
Energy usage:
- ATP --> ADP + P - Creatine Phosphate is a high energy storage compound in muscles - - ATP + CP --> Creatine Phosphate + ADP --> ATP + Creatine
57
Glycogen -
A polysaccharide chain of glucose stored in muscle between myofibrils - Glycogen --> Glucose + ATP
58
Types of stimulus and contraction
Myograms
59
Steps in muscle contraction
Action potential, Ca+ release, Ca+ binds, tropomyosin shifts and unblocks the active site on actin, actin is reattached across myosin

Bio 111 (12 decks)

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