Muscle Structure and Function

Question 1

_____ Muscles mainly line hollow organs (eg gut, blood vessels) and are not
under voluntary control.

Answer 1

Smooth

Question 2

_____ muscle is located only in the heart, it generates force to pump blood
around the body and is not under voluntary control.

Answer 2

Cardiac

Question 3

_____ muscle applies force to the bones to control posture and body
movements. It is mostly under voluntary control.

Answer 3

Skeletal

Question 4

Which muscle type(s) are made up of cells called fibres

Answer 4

All 3
Skeletal, Cardiac, Smooth

Question 5

Volunatary control in muscles is…

Answer 5

Being in control
(Using mind to control and activate them)

Question 6

Muscles develop force by contracting (True or false)

Answer 6

True

Question 7

…Individual muscle cells are called muscle fibres, They
gather into bundles called ____

Answer 7

Fascicles
[Fa-Sick-Kill]

Question 8

*Fascicles are further bundled into _____

Answer 8

Muscles

Question 9

A muscle fibre is comprised of bundles of myofibrils, which are made of repeating
units known as ______

Answer 9

sarcomeres

Question 10

What is a sarcomere?

Answer 10

-The basic contractile unit of a muscle fiber.
- Made up of actin (thin) and myosin (thick) filaments.
- Shortens during muscle contraction to generate force.

Question 11

Whats special about apperance of skeletal muscle cells?

Answer 11

-Long and tube-like
(Due to repeating sarcomeres)

Question 12

The ______ is the muscle fiber’s version of the phospholipid bilayer (cell membrane).

Answer 12

sarcolemma (Sar-Co-Lemma)

Question 13

What is the job of the SR (Sarcoplasmic reticulum) which is wrapped around muscle cells

Answer 13

The sarcoplasmic reticulum (SR) in muscle cells is responsible for **storing, releasing, and reabsorbing calcium ions (Ca2+)

Question 14

Sarcoplasmic reticulum (SR) is associated with the T tubules at regular intervals?
(True false)

Answer 14

True
Transverse tubules (t-tubules) are extensions of
the sarcolemma deep into the fibre.

Question 15

What are the three key proteins involved in excitation during Excitation-Contraction Coupling (EC-Coupling?

Answer 15

DHPR (voltage sensor), RyR (calcium channel), SERCA (calcium pump).

Question 16

How does the signal lead to muscle contraction in EC-Coupling?

Answer 16

The electrical signal travels down the T-tubules, activates a receptor (DHPR), which then triggers another receptor (RyR) on the SR to release calcium, causing the muscle to contract.
The signal is coming from the nerves running throughout the muscle
(If Lost look at diagram on One note skeletal muscles)

Question 17

How does the muscle relax in EC-Coupling?

Answer 17

After contraction, calcium is pumped back into the SR by Calcium Pump using ATP, reducing calcium in the cell and allowing the muscle to relax.

Question 18

striated appearance is like..

Answer 18

Striped
(Like long strips)

Question 19

Transverse tubules (T-tubules) are tube-like
extensions of the sarcolemma.
What is their job

Answer 19

Their job is to conduct electrical signals
(action potentials) deep into the core of the
fibr

Question 20

*When the nerves signal to the muscle that it’s time to contract, how does
that signal get inside the cell and how does it cause a contraction? How
is the signal stopped so the contraction can end?

Answer 20

A motor neuron sends an electrical signal (action potential) down its axon.
It then binds to binds to sarcolemma, triggering an action potential in the muscle cell.
The action potential spreads along the sarcolemma and travels deep into the muscle fiber through T-tubules (invaginations of the membrane).
T-tubules carry the signal to the sarcoplasmic reticulum (SR), which stores calcium ions (Ca²⁺).
Then the nerve signal stops and Ca²⁺ is pumped back in.

Question 21

Sarcomeress are at the _____ level
(size of them)

Answer 21

cellular

Question 22

In EC-Coupling RyR are the

Answer 22

Passive channel for Ca2+ to flow for muscle contraction

Question 23

In EC-Coupling DHPR are the

Answer 23

Voltage sensors
(Voltage from nerves telling muscle to contract)

Question 24

In EC-Coupling SERCA are the

Answer 24

ATP pump
(That pumps Casium back into Sarcoplasmic reticulum to relax the muscle)

Question 25

In T Tubles the (T) stands for (Prolly not important)

Answer 25

Transverse

Question 26

Tropomyosin is

Answer 26

The ribboin-like protein that wraps around actin that blocks myosin heads touching the actin for EC coupling

Question 27

Troponin is

Answer 27

The ball-like protein that blocks myosin heads touching the actin for EC coupling

Question 28

How does Calcium ions allow Myosin heads to pull on Actin

Answer 28

When Ca²⁺ is released from the sarcoplasmic reticulum, it binds to troponin, causing tropomyosin to shift and expose myosin-binding sites on actin. This allows myosin to bind, triggering muscle contraction.

Question 29

The Cross-Bridge Cycle for EC-Coupling

Answer 29

The head is attached to actin. Cross-Bridge Detachment – ATP binds to myosin, causing it to release actin. Myosin Reset (Reactivation) – ATP hydrolyzed → myosin head recocks (ADP + Pi). Cross-Bridge Formation – Myosin head (with ADP + Pi) binds to actin. Power Stroke – Pi is released → myosin pulls actin → ADP released.

Question 30

What two factors determine skeletal muscle force generation?

Answer 30

Recruitment (number of fibers contracting) and frequency of stimulation.

Question 31

What happens when the frequency of stimulation is super high in skeletal muscles?

Answer 31

It reaches tetanus, resulting in maximum possible force.

Question 32

What is a characteristic of muscles rich in fast fibers?

Answer 32

They produce a lot of force quickly but tire out quickly due to limited energy reserves. They are WHITE

Question 33

What is a characteristic of muscles rich in slow fibers?

Answer 33

hey can generate a lot of energy over time and are difficult to fatigue. They are RED

Question 34

Fibres are covered in

Answer 34

Endomysium

Question 35

Fascicles are covered in

Answer 35

Perimysium → Covers fascicles

Question 36

Muscle (whole thing) → Covered by ___

Answer 36

Epimysium

Question 37

Which of these describes an eccentric muscle contraction? A) Muscle shortens while generating force B) Muscle lengthens while generating force C) Muscle generates force without changing length D) Muscle fibers fatigue and stop contracting

Answer 37

B) Muscle lengthens while generating force

Question 38

What occurs in a concentric muscle contraction? (think about Biceps in curl)

Answer 38

The muscle shortens while generating force, such as lifting a dumbbell during a bicep curl.

Question 39

What defines an isometric muscle contraction? (think about Biceps in curl)

Answer 39

The muscle generates force without changing length, like holding a plank or carrying an object steady.

Question 40

What happens during an eccentric muscle contraction?

Answer 40

The muscle lengthens while generating force, often to control movement, like lowering a dumbbell.

Question 41

Which of the following occurs when a muscle is in tetanus? A) The muscle contracts and relaxes rapidly B) The muscle fails to contract C) The muscle remains in a sustained contraction D) The muscle generates a weak contraction

Answer 41

C) The muscle remains in a sustained contraction

Question 42

Which muscle is the prime mover for knee extension? A) Biceps femoris B) Gastrocnemius C) Rectus femoris D) Tibialis anterior

Answer 42

C) Rectus femoris

Question 43

2 Arrangement patterns of Muscle fibres

Answer 43

Parallel (Self explanitory) and Pennate (Diagonal, so more fibres in same area giving them morepulling power, but now less ROM due to shorter fibres)

Question 44

Penate muscles are _____ able to Contract further than Parallel muscle and provide a ______ maximum contraction force than Parallel

Answer 44

1) Less 2) Greater

Question 45

Liam Lawson Is..

Answer 45

Washed