Signalling in the Muscle Skeletal System

Question 1

What are the types of muscles in vertebrates?

Answer 1

Cardiac (striated and involuntary), skeletal (striated and voluntary), and smooth muscle (unstriated and involuntary)

Question 2

How are skeletal muscles attached to bones?

Answer 2

Connective tissues called tendons; skeletal muscles are controlled by the somatic nervous system

Question 3

What is the type of skeletal muscle contractions?

Answer 3

Neurogenic, which means tehy require synaptic input from motor neurons

Question 4

Type of contraction in smooth and cardiac muscles?

Answer 4

Myogenic, which means the contraction activity is a property of the cells that compose the tissues; modified by the ANS

Question 5

What are varicosities?

Answer 5

Allow terminal expansion of terminal axons; they allow muscles to be contracted in a coordinated fashion; they are vesicles that contain mitochondria and neurotransmitters

Question 6

How are muscle fibres bound?

Answer 6

by connective tissue termed fascicles

Question 7

What is responsible for the passive elasticity of muscle?

Answer 7

Titin, which binds actin and myosin

Question 8

Briefly describe how muscle contraction occurs

Answer 8

Motor neurons from the somatic NS generate APs that release Ach; this binds at the neuromuscular junction, and binds to nicotinic receptors in the cell’s membrane; Ca is released from the SR; now it binds troponin to drag of tropomyosin

Question 9

What decreases myosin’s affinity for actin?

Answer 9

Binding of ATP; not hydrolyzed

Question 10

How does the power stroke muscle movement thing work?

Answer 10

ATP binds to myosin head and is hydrolyzed; this energizes myosin and causes a conformational change and bidning to a different site on the actin; causes myosin head to “snap” toward the tail and pull the thin filament over the thick filament

Question 11

Maximal force produced in fast and slow fibres stays the same, speed varies

Answer 11

ye

Question 12

Slow oxidative fibres?

Answer 12

• Contain a large number of mitochondria, meaning they have a high capacity for oxidative phosphorylation and therefore energy production
• Exists in ducks
• Is red because of all the blood vessels containing myoglobin to transfer oxygen
• Have low rates of myosin Atpase activity but make larges amounts of ATP
• Good for flight, long-distance swimming

Question 13

Fast oxidative fibres

Answer 13

 Do not fatigue easily
 Have high myosin ATPase activity and make large amounts of ATP
 Good for long-term activity
 Also good for rapid actions; e.g. trilling made by throat muscles in song birds

Question 14

Fast glycolytic

Answer 14

• Few mitochondria but high concentration of glycolytic enzymes and large stores of glycogen
 Limited use of oxygen
 Few blood vessels, so pale in colur
• Have high myosin ATPase activity but make relatively low amounts of ATP compared to oxidative fibres
• Best for rapid, short actions (such as weight-lifting)
• Fatigue more rapidly