muscle systems - action/myosin

Question 1

how many primary tissues are there in the human body

Answer 1

1. connective tissue
2. epithilial tissue
3. muscle tissue
4. nervous tissue

Question 2

what are muscles

Answer 2

made up of small fibres

Question 3

what are the 3 main types of muscles and their features

Answer 3

CARDIAC MUSCLE :

• Involuntary
• Branched
• 1 or 2 nuclei on each fibre

SMOOTH MUSCLE :

• In hollow organs like (stomahc, blood vessels)
• Involuntary
• Spindle shaped
• Smooth
• Single nucleus in each fibre

SKELETAL MUSCLE :

[most abundant - 650]

• Attached to a tendon on a bone (arms, legs) or directly
• Voluntary - you choose
• Long and tubular
• Striated
• Many nuclei on each fibre

Question 4

what is a sarcromere in muscle tissue?

Answer 4

A sarcomere is the smallest unit in a muscle that helps it contract and move.

Question 5

what are the functions of muscles

Answer 5

movement
maintaining posture and body position (skeletal)
stabilizing jooints
generating heat (skeletal)
propels food
control pupil size
express emotions
protect internal prgans

Question 6

what is a myocyte/ muscle fibre

Answer 6

A muscle cell—long, tube-shaped, and responsible for muscle contraction.

Question 7

what is a myofibril

Answer 7

Tiny threads inside a muscle fibre that are made of repeating units called sarcomeres.

Question 8

what are myofilaments

Answer 8

The proteins (actin and myosin) inside myofibrils that actually do the contracting.

Question 9

myofibrils vs myofilaments

Answer 9

Myofibrils are long strands inside muscle cells.

Myofilaments are the tiny proteins inside those strands.

Question 10

what is the sarcoplasmic reticulum

Answer 10

A special type of smooth ER in muscle cells that stores and releases calcium for muscle contraction

Question 11

what is the sarcolemma

Answer 11

The cell membrane of a muscle fiber

Question 12

A young athlete is very good at long-distance running but is not good at sprinting.
Discuss how this difference relates to the types of muscle fibre in his legs

Answer 12

• 🏃‍♂️ Long-distance running (endurance)
  He is good at this because he likely has more slow-twitch muscle fibers (Type I), which are:

Fatigue-resistant – good for long periods of activity

Use aerobic respiration (with oxygen)

Have lots of mitochondria and blood supply

Generate less power but can keep going longer

• 🏃‍♂️ Sprinting (short bursts of speed)
  He is not good at this likely because he has fewer fast-twitch muscle fibers (Type II), which are:

Powerful and fast but tire quickly

Use mostly anaerobic respiration (without oxygen)

Better for short, intense bursts like sprinting or jumping

Question 13

name the two myofilaments found in a skeletal fibre that give it its striated appearance

Answer 13

actin and myosin

Question 14

what is the fucntion of the sarcoplasmic reticulum in the skeltal muscle tissue

Answer 14

The sarcoplasmic reticulum (SR) in muscle tissue:

Stores calcium.

When the muscle needs to contract, it releases calcium.

The calcium helps the muscle fibers contract by allowing actin and myosin to interact.

After contraction, the SR puts the calcium back so the muscle can relax.

In short, the SR controls calcium to make muscles contract and relax

Question 15

what is the organisation of skeletal muscles

Answer 15

muscle
fascicles
muscle fibres
muscle cells
myosytes
myofibrils
thick and thin filaments

Question 16

what are the 3 layers of connective tissue and what are their features

Answer 16

• epimysium - dense irregular connective tissue
  (biggest one)
• perimysium - surrounds the fascicle (this surrounds the muscle fibres)

-enfomysium - covers the muscle fibre

Question 17

sacrolemma vs sarcoplasm

Answer 17

sarcolemma - cell membrane of a muscle cell

sarcoplasm - cytoplasm of a muscle cell

Question 18

what are glycosomes

Answer 18

granules of stored glycogen

Question 19

what is myoglobin

Answer 19

a red pigment which stores oxygen

Question 20

what is the sarcoplasmic reticulum

Answer 20

specialised smooth endoplasmic reticulum which stores and releases CALCIUM

Question 21

does smooth muscle contain myofibrils

Answer 21

does not contain myofibrils but contains myofilaments actin and myosin

Question 22

what is the role of calcium

Answer 22

calcium binds to troponin and causes it to pull tropomysin away from the actin strands so the heads are now out

Question 23

Explain how having more mitochondria, myoglobin and glycosomes in their muscle fibres enables marathon runners to run for longer distances than sprinters

Answer 23

Marathon runners can run for longer distances than sprinters mainly because their muscles are adapted for endurance rather than short bursts of power. These adaptations include having more mitochondria, myoglobin, and glycosomes in their slow twitch muscle fibres. Here’s how each of these helps with endurance:

1. More Mitochondria
   
   • Mitochondria are the “powerhouses” of the cell; they carry out aerobic respiration, producing ATP, the energy molecule needed for muscle contractions.

   • In endurance activities like marathon running, energy needs to be produced slowly but continuously over a long period.

   • More mitochondria allow muscle fibres to generate more ATP over time using oxygen and fuel sources like glucose and fatty acids.

   • This supports sustained muscle activity without fatigue.

2. More Myoglobin
   
   • Myoglobin is a protein that binds and stores oxygen in muscle cells.

   • It gives slow twitch fibres their red color.

   • Having more myoglobin means the muscle can store and deliver more oxygen to mitochondria.

   • This ensures a steady supply of oxygen for aerobic respiration, allowing marathon runners to keep going without switching to anaerobic respiration (which causes fatigue more quickly due to lactic acid build-up).

3. More Glycosomes
   
   • Glycosomes are storage sites for glycogen, a form of carbohydrate stored in muscle.

   • Glycogen is a key fuel source for making ATP during prolonged activity.

   • With more glycosomes, slow twitch fibres have a larger reserve of energy, which is crucial for endurance events like marathons.


Question 24

• There are two main types of skeletal muscle fibre: slow twitch and fast twitch. Marathon runners have a higher percentage of slow twitch fibres in their skeletal muscles. There are more mitochondria in slow twitch fibres than in fast twitch fibres. Marathon runners can run longer distances than sprinters

Answer 24

Marathon runners have more slow-twitch muscle fibres, which are good for endurance. These fibres:

Have more mitochondria, which produce energy using oxygen (aerobic respiration).

Work for a long time without getting tired.

Are ideal for long-distance running.

Sprinters, on the other hand, rely more on fast-twitch fibres, which:

Produce quick, powerful movements.

Get tired faster.

Use less oxygen and more anaerobic energy.

So, marathon runners can run longer distances because their muscles are built for long-lasting energy and endurance.

Question 25

slow twitch muscle fibres

Answer 25

slow-twitch muscle fibers, which move more slowly but help to keep you moving longer | Feature | **Slow Twitch Fibers (Type I)** | **Fast Twitch Fibers (Type II)** | | -------------------------- | -------------------------------------------------------- | ---------------------------------------------------------------------- | | **Contraction Speed** | Slow (contract more slowly) | Fast (contract rapidly) | | **Force Generated** | Low force production | High force production | | **Fatigue Resistance** | High endurance, fatigue-resistant | Fatigue quickly, suited for short bursts | | **Energy Source** | Primarily **aerobic metabolism** (using oxygen) | Primarily **anaerobic metabolism** (using glycogen, no oxygen) | | **Mitochondria Content** | High, many mitochondria | Low, fewer mitochondria | | **Myoglobin Content** | High (stores oxygen) | Low (less reliance on oxygen) | | **Capillary Density** | High, rich blood supply for oxygen and nutrient delivery | Low, fewer capillaries for blood flow | | **Fiber Color** | Dark red (due to high myoglobin content) | White or pale (less myoglobin) | | **Role in Movement** | Suited for sustained, low-intensity activity | Suited for quick, powerful bursts of energy | | **Fat Storage** | High, can store fats for energy over time | Low, relies more on glycogen stores | | **Key Muscle Groups** | Postural muscles (e.g., muscles in the back, core) | Muscles used in sprinting, weightlifting, or other explosive movements | | **Example Activities** | Long-distance running, cycling, swimming, walking | Sprinting, weightlifting, high-intensity sports | | **Adaptation to Training** | Increase in endurance, efficiency in using oxygen | Increase in power, muscle size, and strength |