CH11 Musculoskeletal Sytem

Question 1

Types of Muscle:

1. Skeletal (white vs red fibers)
2. Smooth Muscle
3. Cardiac Muscle

what is (Myogenic activity)

Answer 1

Types of Muscle:

1. Skeletal: Voluntary movement striated due to sarcomeres (actin and myosin repeating units). Red fibers contain a lot more myoglobin (oxygen carries) endurance muscles i.e for posture. White fibers=fast-twitch muscles
2. Smooth Muscle: Not striated, one nucleus Involuntary muscle movements. i.e digestive system, bladder, respiratory tract, blood vessel walls. Also, it can contract without nervous system signal (Myogenic activity)
3. Cardiac Muscle: Striated, can have multiple nuclei, involuntary. Cell connected by gap junctions for easy ion flow

Question 2

The Sarcomere composition

• Think
• Thick
• I, Z, A, H, M

Answer 2

The Sarcomere:

• Thin: Actin with troponin and tropomyosin
• Thick: bundles of myosin
• I = thin (thin filaments only
• Z= at the end of the sarcomere
• H = thick letter (thick filaments only)
• A = All thick filaments with some thin
• M = middle of myosin filaments

Question 3

Myofibrils and sarcoplasmic reticulum

and muscle fiber, what makes what

Answer 3

Sarcomeres attached end-to-end are called myofibrils.

Surrounded by sarcoplasmic reticulum (SR)

A myocyte (muscle Cell) contains many myofibrils in parallel which is then called a muscle fiber

Question 4

Muscle contraction Stages:

1. Acetylcholine from synapse binds to receptor on the sarcolemma causing depolarization
2. AP travels down the T-tubules and reaches sarcoplasmic reticulum and releases Ca+2
3. Ca2+ binds to troponin causing a conformational change in tropomyosin which expose actin
4. Myosin attaches to actin
5. ADP and P1 dissociate from myosin and causes pull on the actin towards the M line
6. New ATP attaches and causes Myosin to disconnects
7. ADP and Pi are formed and cycle beings again

Answer 4

Muscle contraction Stages:

1. Acetylcholine from synapse binds to receptor on the sarcolemma causing depolarization
2. AP travels down the T-tubules and reaches sarcoplasmic reticulum and releases Ca+2
3. Ca2+ binds to troponin causing a conformational change in tropomyosin which expose actin
4. Myosin attaches to actin
5. ADP and P1 dissociate from myosin and causes pull on the actin towards the M line
6. New ATP attaches and Myosin disconnects
7. ADP and Pi are formed and cycle beings again

Question 5

Bones, tendons, and ligaments

Osteoblasts vs Osteoclasts

effect of:

• Parathyroid hormone
• Vitamin D
• Calcitonin

Answer 5

Bones are attached to muscles by tendons and to each other by ligaments

• Osteoblasts: Build bone
• Osteoclasts: resorb bone (chew bone)
• Parathyroid hormone: increase in bone resorption = increases Ca2+ and Phosphate concentrations
• Vitamin D: Increases resorption of bone = stronger bone
• Calcitonin: Increases in bone formation = decreases Ca2+ concentration
  *

Question 6

Bone parts and composition

Red vs yellow marrow

Articular cartilage

Answer 6

Red Marrow: Hematopoietic stem cells generation of all cells in blood

Yellow Marros: composed of fat and is inactive

Articular cartilage: found in bw joints