Midterm :s

Question 1

Myofibrils

Answer 1

specialized contractile organelles of the muscle cell

Contain a lot of sarcomeres arranged in series

Question 2

Sarcoplasmic reticulum

Answer 2

fluid filled tubes and sacs running along and surrounding each myofibril- they store and release calcium into the cells

Question 3

sarcomeres

Answer 3

the functional unit of a myofibril of contraction

Question 4

2 Contractile proteins?

Answer 4

actin and myosin

Question 5

actin

Answer 5

makes up the thin filaments

Question 6

Myosin

Answer 6

Makes up the thick filaments

Question 7

Neuromuscular Junction

Answer 7

axon terminals that form a junction with the sarcolemma of a number of different muscle cells

Question 8

Does the axon terminal or sarcolemma ever touch?

Answer 8

no

Question 9

The Sliding filament mechanism

Answer 9

• once the signal reaches the muscle fibers, it crosses the synaptic cleft
• the signal is then continued by the muscle fibres and spreads out across the sarcolemma
• it then travels down the transverse tubules and stimulates the sarcoplasmic reticulum to release calcium.
• the calcium allows the myosin of the thick filament to with the actin of the thin filament.
• the myosin pulls the actin/thin filaments together
• it disengages and starts the cycle again
• this ratcheting of the filaments uses ATP
• with repetition, it shortens the sarcomere, the myofibril, the muscle fibre, the muscle
• when the aps stop, the sarcoplasmic reticulum pumps calcium back inside (this uses ATP)
• without sufficient calcium, the thick filaments cannot continue their ratcheting of the thin filaments
• tension generation stops

Question 10

Creatine Phosphate

Answer 10

• a molecule that’s stores high amounts of energy in its chemical bonds
• PCr is split by an enzyme, the energy released is used to reform ATP.
• this happens very fast therefore PCr is the first source of energy used when muscle contraction begins
• Provides energy for 3-15 seconds of maximal contraction
• no oxygen needed
• no lactic acid produced (hence anaerobic alactic)

Question 11

Anaerobic Glycolysis

Answer 11

• when muscle activity is continued over time PCr is depleted so glucose is used to restore the ATP
• broken down into 2 molecules of pyruvic acid and 2-3 ATP
• no oxygen, pyruvic acid does not go into the mitochondria it is converted into lactic acid
• the lactic acid diffuses out into the blood
• capable of producing energy for 30-40seconds

Question 12

Aerobic Cellular respiration

Answer 12

this pathway is active when you are able to get oxygen in to the cells.

• oxygen is delivered from disusing in the blood or delivered by myoglobin.
• in the presence of oxygen, pyruvic acid enters the mitochondria and in a series of reactions that use oxygen, produces much more ATP (much more than glycolysis)
• carbohydrates, fats and proteins can be used in this process to make ATP

Question 13

What are the three types of skeletal muscle fibers?

Answer 13

1. Slow Oxidative.
2. Fast Oxidative
3. Fast Glycolytic

Question 14

Isotonic

Answer 14

muscle contraction through a range against a resistance that is not changing

Question 15

Concentric

Answer 15

A shortening contraction

Question 16

Eccentric

Answer 16

A lengthening contraction

Question 17

Isometric

Answer 17

Muscle contraction in which the length of the muscle does not visibly change

Question 18

Flaccidity

Answer 18

A lack of tine from the nerve being damaged or cut.

Question 19

Hypertrophy

Answer 19

Increase in muscle size

Question 20

Atrophy

Answer 20

Decrease in Muscle size

Question 21

Satellite cells

Answer 21

• undifferentiated muscle cells
• actively involved in muscle repair and regeneration
• capacity is limited

Question 22

Epimysium

Answer 22

Connective tissue component

Surrounds the entire muscle

Question 23

Perimysium

Answer 23

Surrounds the fascicles

connective tissue component

Question 24

Endomysium

Answer 24

Surrounds the muscle fibers

Question 25

Intercalated Discs

Answer 25

Junctions that fit between fibres in the heart muscle

Question 26

Autorhythmicity

Answer 26

• Specialized cells cells within the heart can generate their own electrical signals
• they act as a pacemaker