Physiology Muscle Part 2

Front 1

Substances resulting in muscle contractions

Back 1

1. Nicotine

2. Black widow vemon

Front 2

Nicotine in muscles

Back 2

Binds to receptors (mimics ACh)

- causing muscle to contract by releasing Ca++

Causes muscle spasms

Front 3

Black widow spider venom

Back 3

Causes massive release if ACh

- causes a person to stop breathing

Front 4

Long term effects of nicotine and B.W.S venom

Back 4

Depresses firing due to receptors desensitization

Front 5

Muscle tension

Back 5

Force exerted by a muscle or muscle fibre

- determined by # of cross bridges form

Front 6

Individual Muscle tension effected by

Back 6

1. Frequency of stimulation

2. Fibre length

3 size of fibre

4. Fatigue

Front 7

Whole muscle tension affected by

Back 7

1. Number of fibres contracting

2. # fibres/motor units

3. Muscle size

4. Fatigue

Front 8

1 stimulus stages

Back 8

1. One AP (last 1-2msec)

2. Latent period (2msec)

- AP propagating down T-tubules

3. Contraction period (10-100msec)

4. Relaxation

Front 9

Latent period

Back 9

Processes associated with excitation and contraction coupling

Front 10

Single stimulus

Back 10

Produces a twitch = weak contraction and relaxation

Front 11

Contraction period

Back 11

1. Cross bridges form and sliding filiments

2. Ca++ released from SR and taken back rapidly by SR Ca-ATPase

- causes only some of the myosin heads to be actived at a time

Front 12

Relaxation caused by

Back 12

Ca being pumped into SR, (no no bonds form)

ATP releasing myosin heads

Front 13

2nd stimulus causes

Back 13

1. Increase of Ca++ release from SR

2. Increase contraction with increase tension (I.e. wave summation)

Front 14

Incomplete tetanus

Back 14

Quivering of muscles caused by partial relaxation between contractions

Front 15

Complete tenanus

Back 15

No relaxation between contractions

happens only at highest stimuli frequency

Front 16

Highest tension of muscle

Back 16

1. ALL troponin saturated with Ca++

2. Fibres warms from ATP synthesis

3. Occurs normally in body

Front 17

Size of muscle fibre

Back 17

Thicker = more myofibrils/fibre

Thicker = more tension

Increase with exercise and testosterone

Front 18

Types of muscles

Back 18

Fast: white/anaerobic

Slow: red/aerobic (e.g. postural muscles)

Front 19

Muscle tone

Back 19

Low level of tension at a few fibres (generates heat)

Gives firmness to muscle

Front 20

Isotonic muscle contraction

Back 20

Muscle changes length

Uses ATP

Front 21

Isometric muscle contraction

Back 21

Muscle length constant

Uses ATP

Tension increase (cross bridges form but don't shorten)

Front 22

Durning rest muscle energy

Back 22

1. Fatty acids (aerobic)

2. Storage of Glycogen, creatine phosphate and little ATP

Front 23

Energy use in short term exercise

Back 23

Primarily anaerobic

1. Use available ATP (4-6sec)

2. Use Creatine phosphate (15 sec)

3. Muscle glycogen - anaerobic pathway (30 sec)

Front 24

Long term energy for muscles

Back 24

ATP from aerobic pathways

-glucose (from liver)

- fatty acids (used later on)

O2 Sources

- blood and muscle hemoglobin

Front 25

Physiology fatigue

Back 25

Inability to maintain tension

Decrees ATP use (protection)

-depletion of energy supplies (glycogen)

- build up of end products

Front 26

Muscle energy end products

Back 26

1. H+ from lactic acid (muscle contractions compress blood vessel, decress O2 to muscle)

2. Pi (from ATP break down)

- Pi binds to Ca++

- slows release of Pi from myosin

Front 27

Why can failures of AP happen in muscles

Back 27

1. increase of K+ in small T-Tubules, disturbs MP, stops Ca++ release

2. Neurons runs out of ACh (long term)

Front 28

Psychological fatigue

Back 28

Failure of CNS to send commands to muscles (due to lactic acid)