Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

BIOL1008 > Muscles > Flashcards

Muscles Flashcards

1
Q

How many muscles are there in the body

A

Approx 640 muscles

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

What is the strongest muscle?

A

The masseter (i.e. jaw)

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

What is the largest muscle?

A

The gluteus maximus

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

What is the smallest muscle

A

Stapedius muscle

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

What are the main roles of muscles

A

Allow for movement of the body, bones, food, blood and fluids

Responsible for energy metabolism and storage (glycolysis)

Thermoregulation (creates body heat)

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

What are the four basic properties of muscle

A

Contractility
Excitability
Extensibility
Elasticity

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

What is contractility

A

Ability of muscle to shorten with a force. It requires energy and relaxes passively

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

What is excitability

A

Capacity of muscle to respond to stimulation (nerves) - electrical stimulation

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

What is extensibility

A

Muscle can be stretched to its normal resting rate and beyond to a limited degree

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

What is elasticity

A

Muscles return or recoil to resting position when relaxed

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

What % of body mass is skeletal muscle for men compared to women

A

men = 40%

women = 30%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Does muscle mass decrease with agr

A

Yes it decreases, leading to sacropenia (involuntary loss of skeletal muscle) and ultimately loss of physical capacity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How do muscles function (basic)

A

They function by performing opposing actions (agonist and antagonist)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What does the agonist do

A

Agonist causes movement

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

What does the antagonist do

A

Antagonist provides opposite movement to agonist

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

What are the 3 different types of muscles

A

Skeletal

Cardiac (myocardium)

Smooth

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

What is skeletal muscle

A

Muscle attached to skeleton - its responsible for voluntary movement

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

What is cardiac muscle?

A

Forms the heart, which is also responsible for pumping blood, and it is ultimately an involuntary movement

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

What is smooth muscle?

A

Located in tissues and is responsible for controlling diameter of structures and peristalsis (involuntary constriction and relaxation of muscles, causing wave like movement that pushes contents forward in the gut)

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

Explain the structure of muscle fibers (in terms of ascending size)

A

Sarcomeres –> myofibril –> muscle fibre –> muscle bundle –> muscle

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

What are sarcomeres made up of?

A

Made up of actin and myosin filaments

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

What are actin filaments

A

These are the thin contractile filaments compared to myosin

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

What are myosin filaments

A

These are the thick contractile filaments compared to actin

24
Q

Explain the process of muscle contraction

A

1) ATP bound myosin is in the relaxed position

2) When ATP is dephosphorylated to ADP + Pi (inorganic phosphate), it is positioned to form a cross bridge. Tropomyosin inhibits/blocks binding sites on actin and prevents cross bridge formation

3) Electrical excitation of the muscle cell releases calcium from the sarcoplasmic reticulum. Calcium binds to troponin and moves the tropomyosin out of the way to allow cross bridge formation

4) Power stroke: Release of phosphate bound to the myosin head - myosin head moves along the actin filament

5) At the end of excitation, calcium pumps back into SR allowing tropomyosin to block myosin binding again, and ATP is bound again

25
What is tropomyosin
ropomyosin is the guard mechanism that prevents a skeletal muscle from contracting irregularly or on its own. Tropomyosin is a protein filament used to create a barrier between actin and myosin protein filaments and prevent the skeletal muscle from contracting.
26
What is troponin
Troponin (Tn) is the sarcomeric Ca2+ regulator for striated (skeletal and cardiac) muscle contraction. On binding Ca2+ Tn transmits information via structural changes throughout the actin-tropomyosin filaments, activating myosin ATPase activity and muscle contraction.
27
What is the myosin head
In addition to binding actin, the myosin heads bind and hydrolyze ATP, which provides the energy to drive filament sliding.
28
What are the two different muscle fiber types
Type 1 and Type 2
29
What are type 1 muscle fiber types
They are also called slow twitch and red muscle fibers. They contract slowly, but are slow to fatigue. It uses aerobic (slower) metabolism to generate large amounts of ATP - adapted to deliver O2 to the mitochondria Fibers are red due to the myoglobin content which transports O2 to the area
30
WHat are type 2 muscle fiber types
They are also called fast twitch or white muscle fibers They contract quickly and are fast to fatigue. They use anaerobic (faster) metabolism to generate less ATP - not adapted to deliver O2 to mitochondria
31
WHat are the two types of white muscle fiber
Type 2A and type 2B
32
What does type 2A and type 2B muscles do
Type IIA fibers have high myosin ATPase activity (pH 9.4), are fast twitch, have high oxidative and glycolytic capacity, and are relatively resistant to fatigue. Type IIB fibers have high myosin ATPase activity (pH 9.4), are fast twitch, have low oxidative and high glycolytic capacity, and fatigue rapidly.
33
What are the characteristics of smooth muscles
Single shaped cells without striations Single central nucleus Contracts more slowly with less power than skeletal muscle
34
What are the two types of contractions in smooth muscles
Phasic - rapid Tonic - slower, maintain tension longer
35
Where are smooth muscles formed
Walls of organs, vessels Respiratory tract Eye - dilation constriction of pupil Skin kidneys
36
What is the process of smooth muscle contractions
1) Ca2+ influx into cell from SR and extracellular sources via L type Ca2+ channels 2) Ca2+ binds calmodulin in sarcoplasm 3) Ca2+-/calmodulin activates MLCK which phosphorylates head of myosin filament (ATP) - cross bridge formation 4) No influx - relaxation Overall. There is increase in cytosolic Calcium. Calcium ions bind to calmodulin in cytosol. Calcium calmodulin complex binds to myosin light chain kinase. This kinase uses ATP to phosphorylate myosin cross bridges. Phosphorylated myosin cross bridges bind to actin filaments. The cross bridge cycle produces tension and shortening
37
What are the differences between smooth and skeletal muscle contraction?
Ca2+ binds to calmodulin in cytosol in smooth muscle contraction vs binding to troponin on thin filaments in skeletal muscle MLCK phosphorylation of myosin cross bdirge Smooth muscle contraction is 100-1000 times slower than skeletal - allows smooth muscle to maintain prolonged tonic contraction while consuming little ATP and O2 Stimulus for smooth muscle contraction can be varied - stretch, neural (automatic NS), hormonal, skeletal-innervation(somatic NS)
38
What is a motor unit
It is one motor neuron which supplies a group of muscle cells
39
What are the features of small motor units
Innervate less muscle fibers Generate less tension Enable fine control Fatigue resistant I.e. eye movements
40
What are the features of large motor units
Generate more tension Fatigues more quickly
41
What are slow motor units
Typically help with type 1 fibers - sustained contraction
42
What are fast motor units
Typically help with type 2 fibers - large rapid forces
43
How can an increase in force be generated
By activating more motor units simultaneously
44
What is the overall tension produced in a skeletal muscle a function of?
The frequency of neural stimulation and the number of motor units
45
What are the two types of smooth muscle cells?
Single unit and multi unit
46
What are single unit smooth muscle cells
All cells function collectively and simultaneously as a single unit (unitary) i.e. abdomen or bladder
47
What are multi unit smooth muscle cells
All cells cannot function collectively and instead work independently
48
What are the 3 periods to muscle tension
Latent period, contraction period and relaxation period
49
What is the latent period
Action potential is being propagated along the membrane and Ca2+ ions are released from the sarcoplasmic reticulum
50
What is the contraction period
Period of cross bridge formation
51
What is the relaxation period
When Ca2+ is pumped back into SR and cross bridge cycling stops
52
Describe the muscle tension across the periods of muscle tension
During latent and contraction period it is increasing, and peaks right at the end of the contraction period. Then, during the relaxation period, the muscle tension decreases
53
What is a muscle twitch
It is a single contraction from one action potential from a motor neuron
54
What is the idea of summation in muscle tension
If a muscle cell is stimulated while a previous twitch is still occurring, the second twitch will be stronger. The second stimulus releases more Ca2+ ions and allows more cross bridge formations
55
What is a tetanic contraction
It is a sustained muscle contraction evoked by a motor nerve emitting action potentials at a very high rate
56
What is the sarcoplasmic reticulum
The sarcoplasmic reticulum (SR) is a specialized form of the endoplasmic reticulum of muscle cells, dedicated to calcium ion (Ca2+) handling, necessary for muscle contraction and relaxation.

BIOL1008 (17 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions