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 musle cells called fascicle covered by perimysium.
Many such bundles are covered with epimysium.
Skeletal muscles are syncitial i.e. multinucliated due to fusion of cells.
It shows light and dark bands therefore called striated.
Endoplasmic reticulam is called sarcoplasmic reticulum which stores calcium with protein calsequestrin.
Plasma membrane is sarcolemma covered by endomysium.
Invaginations in plasma membrane are called T-tubules(Transverse tubules) which help in spreading signal deep inside muscle. It is found near Z line and sarcoplasmic reticulum.
Muscle is made up of two types of myofilaments/ myofibrils present in parllely arranged sarcomere.
Two contractile protein are Actin and Myosin:-
Actin:-
Light filament.
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 tropomysin (Regulatory protein).
All regular interval Troponin (Regulatory protein) madre up of 3 subunits are found.
Three subunits of troponin:-
Troponin for inhibition.
Troponin for Tropomyosin.
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 myosin.
One end of actin is free, other joined to the Z membrane .
Diametre = 50 A.
It forms light band.
Myosin:-
Heavy filament.
Polymer of meromyosin-II.
Meromyosn has two parts
Heavy meromyosin(HMM)
Light meromyosin (LMM)
Head has actin binding site at tip and ATP binding site at sides.
Centre of head has ATPase activity.
Diametre-100A.
Free at both ends.
Present in centre of sacomere.
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 bridge with Actin and swirls towards centre of sacomere.
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 require ATP.
Whe 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 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-band reduces.
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 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 non phenomena-There is a minimum threshold value of neurotransmitters required for muscle to contraction below which muscle can`t contract.Any value above this threshold will cause same amount of contraction. Strength of contraction depands upon number of motor units working .
Rigor Mortis- Stiffening of 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 excercise is called oxygen debt . Breathing rate therefore remains high for some time after excercise.
Summation-Many sub-threshold signal when given in a quick manner adds up to cross 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 muscles with opposite action.
-
Flexor - Bends e.g. Biceps .
Extensor -extends e.g. Triceps. -
Abductor - moves arm away from body. e.g. Deltodius.
Adductor- Moves arm towards body . e.g. Latisimus dorsi. -
Depressor- Moves jaw below e.g. Depressor mandibuli
Elevator - Moves jaw up e.g. Massetor
4)Sphinctor
Dilator
- Supinator- Moves palm/sole anterior / up
Pronator- Moves palm/sole posterior/ down.