Locomotion and Movement part 1 notes (Biology)

All locomotions are movement but all movement not locomotion.

Types of movement:-

1) Pseudopodial/ amoeboid:- cyclosis (streaming movement of cytoplasm) e.g. Macrophage.

 2) Ciliary:- e.g. Trachea and fallopian tubes.

3) Flaggelar:- e.g. Sperm 

4) Muscular:-e.g. All body part movement.

Skeletal Muscles:- 

• These are voluntary muscles.
• Fascia is covering of connective tissue present beneath skin surrounding entire muscle.
• Muscle is made up of bundles of muscle cells called fascicle covered by perimysium.
• Many such bundles are covered with epimysium.
• Skeletal muscles are syncytial i.e. multinucleated due to the fusion of cells.
• It shows light and dark bands, therefore, called striated.
• The endoplasmic reticulum is called sarcoplasmic reticulum which stores calcium with protein calsequestrin.
• The plasma membrane is sarcolemma covered by endomysium.
• Invaginations in the plasma membrane are called T-tubules(Transverse tubules) which help in spreading signal deep inside the muscle. It is found near the Z  line and sarcoplasmic reticulum.

• Muscle is made up of two types of myofilaments/ myofibrils present in parallelly arranged sarcomere.

  Two contractile protein are  Actin and Myosin:-
Actin:-

• Light filament.
• The polymer of Globular actin( G- actin)
• G-actin joins to form F-actin (Filament actin).
• Two such filaments coil together to form Actin.
• Each F-actin has its own filament of tropomyosin (Regulatory protein).
• All regular interval Troponin (Regulatory protein) made up of 3 subunits are found.
• Three subunits of troponin:- 

1. Troponin for inhibition. 
2. Troponin for Tropomyosin.
3. Troponin for calcium.

• Each G-actin has myosin binding site which is covered by tropomyosin and troponin at regular interval.
• Actin is surrounded by three myosins.
• One end of actin is free, others joined to the Z membrane.
• Diametre = 50 A.
• It forms a light band.

Myosin:-

• Heavy filament.
• The polymer of meromyosin-II.
• Meromyosin has two parts 

1. Heavy meromyosin(HMM)
2. Light meromyosin (LMM)

•  Head has actin binding site at the tip and ATP binding site at sides.
• Centre of the head has ATPase activity.
• Diametre-100A.
• Free at both ends.
• Present in center of sarcomere.
• Each myosin is surrounded by 6 actin.
• Forms dark band.

 Sliding Filament Theory for muscle contraction:-

• Given by Huxley and Huxley.
• Supported by Niedergerk and Hanson.
• ATP binds to head of myosin.
• ATPase activity of myosin converts ATP into ADP + Pi. This requires magnesium.
• Myosin forms cross the bridge with Actin and swirls towards the center of sarcomere.
• Actin filament slides over myosin causing contraction of sarcomere thus muscle.
• Calcium comes out from SR and binds to troponin. This removes tropomyosin and troponin complex away from myosin binding site of Actin.
• Myosin can now easily bind actin.

Relaxation of muscle:-

• Relaxation of muscle also requires ATP.
• When the new ATP binds to myosin ATP and Pi is removed. This shifts myosin back to its original site and sarcomere relaxes.
• Entry of calcium back into SR is against a concentration gradient. Therefore active transport also requires ATP.

A-band - Anisotropic

I-band - Isotropic 

H-band - Hanson`s

Z-line - memb. of Krauz.

M-line - Middle line 

• A-band never changes its size.
• I and H-bands reduce.

 Motor unit - one neuron plus all muscle cells forms one motor unit. A muscle is made up of many motor units.

Muscle Twitch- Sudden spontaneous contraction followed by relaxation. It is found only in the laboratory.

Muscle Tetanization-Sequential recruitment of motor units to maintain contraction.

Muscle Tone- A very low level and sustained contraction of our back muscle to maintain posture.

All or none phenomena-There is a minimum threshold value of neurotransmitters required for the muscle to contraction below which muscle can`t contract. Any value above this threshold will cause the same amount of contraction. The strength of contraction depends upon the number of motor units working .

Rigor Mortis- Stiffening of the body after death due to depletion of ATP.

Cori Cycle-

Muscle Fatigue-Accumulation of lactic acid at neuromuscular junction causing pain and preventing contraction is called muscle fatigue.

Oxygen Debt- Additional oxygen required to remove all lactic acid formed during exercise is called oxygen debt. Breathing rate, therefore, remains high for some time after exercise.  

Summation-Many sub-threshold signal, when given in a quick manner, adds up to cross a threshold value.

Difference between Red muscle fibres and white muscle fibres-
Red muscle fibres                      White  muscle fibres 
-Tonic muscle                                                       -Twitch muscle.
-High myoglobin .                                                -Less myoglobin.
-High mitochondria                                               - Less mitochondria
-Aerobic respiration                                             - Anaerobic respiration
-No fatigue                                                           -Fatigue
-Slow and sustained contraction                          - Quick and short duration contraction
-Less ER                                                               - Many ER
e.g. back extensor muscle, flight                          -e.g. eye muscle, flight muscle of crow etc.
      muscle of migratory birds 

Antagonistic muscle:-
 Each part is supplied with a pair of antagonist's muscles with opposite action. 

1) Flexor - Bends e.g. Biceps.

    Extensor -extends e.g. Triceps.

2) Abductor - moves the arm away from the body. e.g. Deltodius.
    Adductor- Moves arm towards the body. e.g. Latisimus dorsi.

3) Depressor- Moves jaw below e.g. Depressor mandibuli
     Elevator - Moves jaw up  e.g. Massetor

4)Sphinctor
    Dilator

5) Supinator- Moves palm/sole anterior / up
    Pronator- Moves palm/sole posterior/ down.