Skeletal, smooth and cardiac muscle pt.2

Question 1

Describe how fatigue is a protective mechanism?

Answer 1

stops you contracting muscles for far too long and using up huge stores of ATP and could go into rigor

Question 2

When are we able to stop responding to motor neuron commands?

Answer 2

if muscle feels its going to become damaged or if its exceeding biological limits

Question 3

What happens during high intensity, short duration exercise?

Answer 3

-conduction failure due to potassium accumulating outside the cells far faster than can be put pack in cells
-lactic acid concentration rise as using up glucose and other substrates to generate ATP- acidifies proteins in cellular environment and don’t work as effectively
-if accumulate bi products of ATP hydrolysis too much (ADP and Pi) inhibits cross bridge cycle, delaying myosin detachment from actin filaments

Question 4

What happens during long-term, low intensity exercise?

Answer 4

people tend to get fatigued because they run out of energy stores within muscle
running out of stores of glycogen within muscle
lower blood glucose
dehydration- muscle needs a lot of water

Question 5

What is central command fatigue?

Answer 5

unable to use CNS to excite motor neurons

Question 6

What are the characteristics of faster fibres?

Answer 6

myosin has high ATPase activity

Question 7

Characteristics of slower fibres?

Answer 7

myosin has low ATPase activity- not as good at ATP hydrolysis

Question 8

Describe characteristics of oxidative fibres?

Question 9

Describe characteristics of oxidative fibres?

Answer 9

-far more reliant on oxygen
-more mitochondria- lots of oxidative phosphorylation
-lots of blood vessels nearby
-short buffer storage facility for oxygen (myoglobin)
-fibres are red and have low diameters ( to minimise diffusion distance)

Question 10

Describe characteristics of glycolytic fibres?

Answer 10

-generate ATP via the process of glycolysis
-fewer mitochondria
-increased expression of glycolytic enzymes
-detect glycogen
-lower blood supply
-white fibres with large diameters

Question 11

What are the three types of muscle fibres ?(classified based on ability to resist fatigue)

Answer 11

slow oxidative (I) - resist fatigue
fast oxidative (IIa)- intermediate resistance to fatigue
fast glycolytic (IIb)- fatigue quickly

Question 12

What is recruitment?

Answer 12

increase the number of active motor units

Question 13

Describe the sequence in how muscle fibres are activated?

Answer 13

slow oxidative
then fast oxidative
then
fast glycolytic

Question 14

What does ability to generate control how much tension generated within muscle depend on?

Answer 14

amount of calcium we can release
amount of protein in muscle cells
frequency of APS to motor units
recruitment of motor units

Question 15

What happens if destroy nerve/NMJ?

Answer 15

denervation atrophy - muscle starts to shrink as not receiving that signalling traffic from neurons

Question 16

What happens if stop muscle being used?

Answer 16

nerve intact but get disuse atrophy.
Muscle gets smaller, lower protein content …

Question 17

What happens when we do strength and resistance exercise?

Answer 17

cause micro trauma in muscle
starts to try repair itself by taking in more protein