Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Muscular System > Muscle Tissue > Flashcards

Muscle Tissue Flashcards

1
Q

Skeletal muscle tissue
•Description
•Function
•Location

A

Description:
•long cylindrical multinucleated cells; obvious striations
Function:
•voluntary movement, locomotion, manipulation, facial expression, voluntary control
Location:
•in skeletal muscles attached to bones or occasionally to skin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

3 types of muscle tissue

A
  • skeletal
  • cardiac
  • smooth
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Cardiac muscle tissue
•description
•function
•location

A

Description:
•branching, striated, generally uninucleated cells that interdigitate at specialized junctions
Function:
•as it contracts it propels blood into the circulation; involuntary control
Location
•the walls of the heart

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Cardiac muscle tissue
•description
•function
•location

A

Description:
•branching, striated, generally uninucleated cells that interdigitate at specialized junctions
Function:
•as it contracts it propels blood into the circulation; involuntary control
Location
•the walls of the heart

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Smooth muscle
•Description
•Function
•Location

A

Description:
•spindle shaped cells with central nuclei; no striations; cells arranged closely to form sheets
Function:
•propels substances or objects along internal passageways; involuntary control
Location:
•mostly in the walls of hallow organs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Special physical characteristics of muscle

A

Excitability
Contractility
Extensibility
Elasticity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Excitability

A

The ability to respond to certain stimuli by producing electrical signals (action potentials)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Contractility

A

The ability to shorten forcefully when adequately stimulated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Extensibility

A

The ability to be stretched or extended

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Elasticity

A

The ability to recoil after being stretched

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Muscle functions

A
  • producing movement
  • maintaining posture and body position
  • stabilizing joints
  • generating heat
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Nerve supply

A
  • Has a rich nerve supply
  • Each muscle fibre is innervated by its own nerve ending
  • allows precise neural control of the entire muscle during contraction
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Blood supply

A
  • has a rich blood supply because contracting muscle fibres uses a huge amount of energy and a more or less continuous delivery of oxygen and nutrients
  • muscle capillaries are long and winding
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Connective tissue sheaths

A

Support and reinforce the muscle as a whole
•epimysium
•perimysium
•endomysium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Epimysium

A

Surrounds the whole muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Perimysium

A

Surrounds the fascicles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Endomysium

A

Surrounds each fiber

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Attachments of muscle

A

Skeletal muscles span joints and are attached to bones in at least two places
•during contraction the insertion (moveable bone) moves towards the origin (less/immovable bone)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Direct attachments

A

The muscles epimysium is fused to the bones periosteum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Indirect attachments

A

The muscles connective tissue sheaths are attached to the bone either as a rope like tendon or as a sheet like aponeurosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the sarcolemma

What does it have

A
  • Plasma membrane

* T tubules that help an electrical impulse to get to the cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is the sarcoplasm

A

The cytoplasm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is different about the sarcoplasm in a skeletal muscle fiber

A

Contains large amounts of
•glycosomes: bags of glycogen
•myoglobin: red coloured protein stores oxygen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Specialized organelles

A
  • myofibrils
  • sarcoplasmic reticulum
  • T tubules
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Myofibrils

A
  • rodlike, run the length of the cell
  • myofibrils are composed of myofilaments that are organized into sarcomeres
  • has repeating light and dark bands
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Sarcomere

A
  • Smallest contractile unit of muscle fibre
  • the region between two Z disks
  • aligned end-to-end like boxcar trains
27
Q

Proteins that make up the thick and thin filaments

A
  • Myosin

* Actin

28
Q

What are the A bands thick filaments composed primarily of

A

Myosin protein

29
Q

Myosin protein and the muscle fibres

A

Contains ATP binding sites as well as ATPase enzymes.

•During contraction they form cross-bridges with thin filaments that overlap with thick filaments

30
Q

What are the I bands thin filaments primarily composed of

A

Actin protein

31
Q

Actin protein and muscle fibres

A
  • Has a myosin binding site which forms cross-bridges with to produce contraction
  • Each thin filament is composed of two strands of actin molecules twisted together one end of the strand is firmly attached to the Z disk
32
Q

What are two important regulatory proteins also present in thin filaments

A

•tropomysin
•troponin
Both help control the myosin-actin interactions involved in contraction

33
Q

Tropomysin

A

Rod shaped protein that spirals around each thin filaments and helps stiffen and stabilize it.
•In relaxed muscle fibre it blocks the myosin binding sites on actin so that the myosin heads on the thick filaments cannot bind to the thin filaments

34
Q

Troponin

A 
Globular three polypeptide complex, 
•one part binds to actin 
•another binds to tropomysin 
•the third part binds to calcium ions 
During muscle contraction troponin is signalled by calcium ion to lift tropomysin off the thin filament exposing it's myosin binding sites to the thick filaments
35
Q

Structural proteins involved in the contractile of muscles

A
  • Titin

* dystrophin

36
Q

Sarcoplasmic reticulum

And it’s major role

A

An elaborate network of smooth endoplasmic reticulum wrapped around each myofibril.
•to regulate intracellular levels of ionic calcium
•stores calcium and releases it on demand for contraction

37
Q

T tubules

A

At each A band I band junction is a hole going deep into the cell coming close in contact with the sarcoplasmic reticulum called T tubules

38
Q

What is the sliding filament theory of contraction

A

During contraction the thin filaments slide past the thick filaments.

39
Q

How does the sliding filament theory work

A

When muscle fibres are stimulated by the nervous system, the myosin heads of the thick filaments latch onto the myosin binding sites of the actin molecules making up the thin filaments.
The sliding of filaments and the shortening of sarcomeres causes the shortening of the whole muscle fibre and the entire muscle

40
Q

Overview of skeletal muscle contraction
3 events that must occur for a skeletal muscle fibre to contract
1st event is..

A

1) the fibre must be activated by a nerve ending causing a change in the fibres membrane potential
•action potential (AP) arrives at axon terminal at neuromuscular junction
•Ach released; binds to receptors on sacrolemma
•local change in membrane potential occurs (depolarization)
•local depolarization ignites AP in sarcolemma

41
Q

Overview of skeletal muscle contraction
3 events that must occur for a skeletal muscle fibre to contract
2nd event is..

A

2) the fibre must generate and propagate an electrical current (action potential) along its sarcolemma and down its T tubules

42
Q

Overview of skeletal muscle contraction
3 events that must occur for a skeletal muscle fibre to contract
3rd event is..

A

Ionic calcium must be released from the sarcoplasmic reticulum (SR)to trigger contraction
•SR releases ca2+; binds to troponin; myosin binding sites on actin exposed
•myosin heads to actin; contraction begins

43
Q

Where do action potentials arise

A

The neuromuscular junction

44
Q

What is a neuromuscular junction

A

The synapse between a somatic motor neuron and a skeletal muscle fiber.

45
Q

What is a synapse

A
  • Is a region of communication between two neuroma or a neuron and a target cell (ie skeletal muscle cell)
  • synapses separate cells from direct physical contact, neurotransmitters bridge that gap
46
Q

What neurotransmitter is at a neuromuscular junction

A

Acetylcholine (ACh)

47
Q

What happens when a nerve impulse reaches the neuromuscular junction and acetylcholine is released?

A

Ach binds to sarcolemma receptors which causes a change in sarcolemma permeability leading to a change in membrane potential.

48
Q

What first three events occur at the neuromuscular junction

A

1) action potential arrives at motor neurons axon terminal
2) voltage-gated ca channels open and ca enters the axon terminal
3) ca entry causes some synaptic vesicles to release acetylcholine by exocytosis

49
Q

What last three events occur at the neuromuscular junction

A

4) Ach diffuses across the synaptic cleft and binds to receptors in sarcolemma
5) Ach binding opens ion channels that allow Na to diffuse into the cell and K to diffuse out of the cell; more Na enters than K leaves, producing a local change in the membrane potential (depolarization)
6) Ach effects are terminated by its enzymatic breakdown in the synaptic cleft by acetylcholinesterase

50
Q

What is the potential of the sarcolemma

A

It is polarized

A potential difference across the membrane with the inside negative.

51
Q

Action potential

A

The act of releasing energy
Involves two steps:
•depolarization
•repolarization

52
Q

Depolarization

A

The binding of Ach to Ach receptors in the sarcolemma opens ion channels that allow Na to diffuse into the cell and K out. More Na moves then K causing a change in the membrane potential called depolarization

53
Q

Repolarization

A
  • Depolarization quickly returning to resting state– negative on the interior relative to the exterior
  • a result of the opening of membrane K channels, allowing K to diffuse rapidly out of the cell and repolarize it.
54
Q

Excitation-contraction coupling

A

Describes the events that connect nervous excitation of a skeletal muscle fibre to its contraction.

55
Q

Excitation-contraction coupling:

What happens when a nerve stimulates a muscle fibre

A

1)a nerve stimulating a muscle fibre sends an action potential along its sarcolemma down T tubules towards the sarcoplasmic reticulum

56
Q

Excitation-contraction coupling:

What happens when the action potential reaches the SR

A

When the action potential reaches the sarcoplasmic reticulum’s terminal cisterns, voltage gated Ca release channels in the SR open

57
Q

Excitation-contraction coupling:

What happens when the ca voltage gated channels open

A

Ca pours into the cytosol where it binds with troponin, causing it to change shape
Troponin moves tropomyosin away from the myosin-binding sites on actin
Myosin is now free to bind with actin-the contraction cycle begins

58
Q

Excitation-contraction coupling:

Contraction cycle

A

Continues until Ca active transport pumps return Ca to the sarcoplasmic reticulum. When Ca2 levels drop in the cytosol, tropomyosin falls back onto actin’s myosin binding sites and the contraction cycle stops

59
Q

The cross bridge cycle

A

A series of events during which myosin heads pull thin filaments toward the centre of the Sarcomere

60
Q

Steps of the cross bridge cycle

A

1) myosin heads hydrolysis ATP and become reoriented and energized
2) myosin heads bind to actin, forming crossbridges
3) myosin crossbridges rotate toward centre of the Sarcomere
4) as myosin heads bind ATP the crossbridges detach from actin

61
Q

The motor unit

A

A motor neuron and the muscle fibres it stimulates

The motor unit is the functional unit of skeletal muscle

62
Q

One single motor unit may innervate..

A

As few as 10 or as many as 2000 muscle fibres with an average of 150 fibres being innervated by each motor neuron

63
Q

The function of the motor unit

A

Stimulation of a single motor unit produces weak contraction of the entire muscle
Muscles that control precise movements consist of many small motor units, each consisting of a motor neuron and 10-20 muscle fibres

Muscular System (1 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions