muscle function

Question 1

explain muscle metabolism on terms of creatine phosphate

Answer 1

Creatine phosphate is Rapid changes from very low ATP consumption to high levels of consumption can happen very quickly

Creatine phosphate= a rapidly metabolite in skeletal muscle and brain (high energy store)

Fast & good for ~ 15 sec (so not very long lasting source of energy, but is fast responding)

Question 2

explain glycolysis in terms of for producing energy for muscle function

Answer 2

Break down 1 molecule of glucose to 2 pyruvates yielding 2 ATP molecules

If insufficient mitochondria or oxygen, pyruvate => lactic acid

Get about 30-40 seconds more at max of energy than from phosphocreatine.

This is not the greatest source of ATP, as for every glucose, 2 ATP produced

Question 3

which metabolic process provides the greatest ATP abundance

Answer 3

Aerobic Cellular Respiration

Question 4

explain aerobic cellular respiration in terms of for producing energy for muscle function

Answer 4

Provides greatest abundance of ATP.

This is often called krebs cycle/ citric acid cycle

Production of ATP occurs in mitochondria

Requires oxygen and carbon substrate

Produces CO2 and H2O and heat byproducts.

Question 5

what is muscle fatigue

Answer 5

Inability to contract forcefully after prolonged activity due to being worked continually

Question 6

name some factors that can limit muscle contraction such as in muscle fatigue

Answer 6

Ca2+
Creatine Phosphate
Oxygen
Build up of acid
Neuronal failure

Question 7

explain oxygen use after exercise

Answer 7

Lactic acid converted back to glucose in liver from the muscle, this will be used to once again synthesize glucose

Liver stores glucose for transport to other tissues

Creatine Phosphate and ATP can be resynthesized, and used in tissues to drive contraction and other processes

Oxygen binds to deoxymyoglobin to form myoglobin again to correct some of those deficiencies after long periods of prolonged exercise have depleted the muscle of its oxygen

Question 8

Diff types of muscle contraction occur depending on what

Answer 8

on the strength of the stimulus that it receives

Question 9

name the 4 types of muscle contraction

Answer 9

Single Action Potential (AP)

wave summation

unfused tetanus

fused tetanus

(weakest to strongest force of contraction)

Question 10

describe single Action Potential (AP)

Answer 10

creates a twitch

Contraction that’s Smaller than maximum muscle force

Question 11

what does Total tension of fibre depend on

Answer 11

on frequency of APs (number/second)(no large or small, but frequ which they receive will dictate the force of contraction that occurs)

• Requires wave summation
• Maximum = tetanus (muscle cannot contact anymore)

Question 12

what does Total tension of muscle depend on

Answer 12

on number of fibres contracting simultaneously

Increasing numbers = Motor unit recruitment (the more motor units you have, the greater the contraction will be)

Question 13

what are the 3 parts to a force of contraction

Answer 13

latent period (flat part before the increase in force)

contraction period (increasing part in force)

relaxation period (when force starts to decrease)

Question 14

name the 3 fibre types

Answer 14

slow oxidative (SO)

fast oxidative - glycolytic (FOG)

fast glycolytic fibres (FG)

Question 15

explain Slow oxidative (SO) fibres

Answer 15

small diameter & red

large amounts of myoglobin and mitochondria

ATP production is primarily oxidative

Fatigue resistant as effective at carrying oxygen and ATP production

Question 16

explain Fast oxidative- glycolytic (FOG) fibres

Answer 16

Large diameter = so many myofibrils

Many mitochondria and high glycolytic capacity (so glycolysis will be high in these fibres)

Intermediate level

Question 17

explain Fast glycolytic fibres (FG)

Answer 17

white, fastest & powerful and fast fatiguing

Used For strong burst of energy, but short term use

Question 18

describe recruitment in terms of fibres

Answer 18

Muscle contractions only use the fibres for the work required.

Question 19

explain the order of fibre recruitmnet

Answer 19

1. Slow oxidative
2. Fast oxidative – glycolytic
3. Fast glycolytic

Question 20

name the 2 types of contraction

Answer 20

isotonic
isometric

Question 21

explain isotonic contractions

Answer 21

If force is constant and the muscle shortens = Isotonic Contraction (associated with lifting arm or leg)

Question 22

explain isometric contractions

Answer 22

If length is constant and the force varies = Isometric Contraction

The latter is often a postural muscle activity

Question 23

in exercise how is the SO/FG fibre ratio determined

Answer 23

genetically

Question 24

explain high FG fibres in exercise

Answer 24

sprinters (as need strong short burst of energy)

Question 25

explain high SO fibres in exercise

Answer 25

marathon runners (gradual energy release over long period due to their good oxygen supply)

Question 26

what fibres are involved in endurance exercise

Answer 26

exercise gives FG => FOG (fast oxidative – glycolytic) (uses both methods combined)

Increased diameter and numbers of mitochondria

Question 27

what does strength exercise do to FG fibres

Answer 27

increases size & strength of FG fibers

Question 28

explain cardiac muscle appearance and contraction

Answer 28

Striated, short fibres that are branched

Single central nucleus; Cells joined by gap junctions & desmosomes

Thickened joint area called intercalated discs

Some cardiac muscles generate own action potential- autorhythmicity

Involuntary

No nerve input required - internal pacemaker that can be modified by the autonomic nervous system.

Ca2+- from S.R. and extracellular space, this means that contractions are more prolonged.

separate cells with gap junctions -> electrical connections

Question 29

describe smooth muscle

Answer 29

Involuntary

Found in internal organs

Filaments not regular so not striated

Question 30

name the 2 types of smooth muscle

Answer 30

Visceral (single unit) type

Multi-unit type

Question 31

explain the Visceral (single unit) type of smooth muscle

Answer 31

Form sheets and are autorhythmic e.g walls of viscera

Contract as a unit

Question 32

explain the Multi-unit type of smooth muscle

Answer 32

Functions independentaly

each has own nerve and can contract independently e.g. arrector pilii of hair

Question 33

describe the contractions and response of smooth muscle

Answer 33

Graded contractions and slow responses

Question 34

describe the tone that smooth muscle sustains

Answer 34

long term tone

Question 35

what are smooth muscle contractions often triggered by

Answer 35

autonomic nerves

Question 36

what are smooth muscle contractions modulated by

Answer 36

by hormones, local chemical factors , nerves, by mechanical events (stretching) which can all trigger a response to that

Question 37

briefly compare smooth muscle appearance to cardia and skeletal muscle appearance

Answer 37

Smooth muscle fibre has a very Diff appearance from cardiac and skeletal muscle as not straited and its arrangement is very irregular

Question 38

explain the effect of ageing on skeletal muscle mass

Answer 38

There is a slow progressive loss of skeletal muscle mass (atrophy) after the age of 30

• Sarcopenia

Question 39

explain the effect of ageing on the number of slow oxidative (SO) fibres

Answer 39

Relative number of slow oxidative fibres tends to increase, so less ability to carry out fast type

Question 40

what can slow down the changes occurring from ageing on muscle

Answer 40

Endurance and strength training