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Bio 111 > Muscles > Flashcards

Muscles Flashcards

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Biology 101 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
Q

Muscle groups:

- Antagonistic -

A

Muscles perform different functions.

I.e. Triceps brachii which functions to extend the forearm, is antagonistic to the biceps brachii and brachialis.

25
Q

Muscles classified by…?

A

Fiber arrangement.

26
Q
  1. Parallel or fusiform -
A

Contract over a long distance, good endurance, not necessarily strong.
I.e. Sartorius - a strap like muscle over the thigh.

27
Q
  1. Convergent -
A

Fibers converge at the insertion to maximize contraction force. Fan shape.
I.e. Deltoid or pectoralis major.

28
Q
  1. Pennate -
A

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
Q
  1. Circular -
A

Surround body openings.

I.e. Orbicularis oris (mouth), oculi (eye)

30
Q

Blood and nerve supply

A

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
Q

Muscle cell -

A

Multi nucleated, contains the usual cell organelles & is a cylinder up to 30 cm long.
Called a muscle fiber and striated (striped).

32
Q

Sacolemma -

A

Cell membrane

33
Q

Sarcoplasm -

A

Cytoplast

34
Q

Sarcoplasmic reticulum -

A

Endoplasmic reticulum. Modified to pump Ca+ to muscle fibers.

35
Q

Transverse tubules (T tubules)

A

Formed by sacrolemma. Open to the extra cellular fluid. Brings in Ca+ to the sacroplasmic reticulum.

36
Q

Actin -

A

The thin filament in the muscle composed of actin monomers.

Myosin cross bridge

37
Q

Myosin -

A

The thick filament of muscle composed of myosin. (Resembles golf clubs)

38
Q

Sacromere -

A

Unit of contraction in muscle

39
Q

Rigor Mortis -

A

All ATP binding sites are attached. No fresh supply of ATP, so myosin doesn’t detach.

40
Q

Isotonic contraction -

A

Force of contraction remains constant throughout the contraction.

41
Q

Isometric contraction

A

Muscle length is constant. The opposing force = muscle contraction force.

43
Q

Sliding filament theory of muscle contraction:

Myosin -

A

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
Q

Sliding filament theory of muscle contraction:

Actin -

A

Looks like a string of pearls. Each “pearl” monomer has has 3 active sites.

45
Q

Sliding filament theory of muscle contraction:

Tropomyosin -

A

A long chain protein molecule that covers the active sites of actin and prevents contraction.

46
Q

Sliding filament theory of muscle contraction:

Troponin -

A

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
Q

Sliding filament theory of muscle contraction: some steps

A
  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
Q

Neuromuscular junction:

Synaptic knob -

A

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
Q

Neuromuscular junction:

Synaptic cleft -

A

The space that separates the synaptic knob and motor end plate.

50
Q

Neuromuscular junction:

Motor end plate -

A

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
Q

Steps in contraction:

1.

A
  1. Release of ACH from synaptic knob into the synaptic cleft.
    ADH diffuses to motor end plate.
52
Q

Steps in contraction:

2.

A
  1. 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
Q

Steps in contraction:

3.

A
  1. Generation of action potential.
    Depolarization at the end plate spreads across the sarcolemma.
    -Excitability
    -Action potential
54
Q

Excitability -

A

Ability to conduct electrical impulse.

-Only muscle and nerve are excitable.

55
Q

Action potential -

A

Depolarization sweeps across the sarcolemma.

56
Q

Energy usage:

A
  • ATP –> ADP + P
  • Creatine Phosphate is a high energy storage compound in muscles
    • ATP + CP –> Creatine Phosphate + ADP –> ATP + Creatine
57
Q

Glycogen -

A

A polysaccharide chain of glucose stored in muscle between myofibrils
- Glycogen –> Glucose + ATP

58
Q

Types of stimulus and contraction

A

Myograms

59
Q

Steps in muscle contraction

A

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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