Locomotion and Movement Class 11 Notes Biology Chapter 20

 Page 1


Points To Remember
Arthritis : an inflammatory joint disease characterised by inflammation of 
joints.
Coccyx : tail bone formed by fusion of four coccygeal vertebrae in man.
Dicondylic Skull : A Skull with two occipital condyles.
Endo Skeleton : A skeleton present in side the body.
Fascicle : Bundles of muscles fibres held together by connective tissue.
Fascia : Collagenous connective tissue layer that surrounds muscle bundles.
Floating ribs : The ribs that remain free anteriorly, (last 2 pairs)
False ribs : 8th, 9th and 10th pair of ribs not directly joins the sternum but 
to seventh pair of ribs, hence called pseudoribs.
Myoglobin : A red colored pigment present in sarcoplasm of muscle.
Sarcomere : A portion of myofibril between two successive ‘Z’ lines.
Sarcocolema : The plasma membrane of a muscle.
Gout : Inflammation of joints due to accumulation of uric acid crystal.
Suture : immovable joints between skull bones.
Synovial joints : Freely movable joints between limb bones.
Patella : A seasmoid bone acting as kneecap.
Intervertebral disc : Fibro cartilaginous pad present between the vertebrae 
that act as shock absorbers.
Tendon—Connective tissue made of yellow fibrous tissue which connect 
muscle to bone. It is not flexible.
Ligament—Connective tissue made of white fibrous tissue which joins two 
bones. It is flexible.
L.M.M. : Light meromyosin
HMM : Heavy meromyosin
Types of Movement :
Page 2


Points To Remember
Arthritis : an inflammatory joint disease characterised by inflammation of 
joints.
Coccyx : tail bone formed by fusion of four coccygeal vertebrae in man.
Dicondylic Skull : A Skull with two occipital condyles.
Endo Skeleton : A skeleton present in side the body.
Fascicle : Bundles of muscles fibres held together by connective tissue.
Fascia : Collagenous connective tissue layer that surrounds muscle bundles.
Floating ribs : The ribs that remain free anteriorly, (last 2 pairs)
False ribs : 8th, 9th and 10th pair of ribs not directly joins the sternum but 
to seventh pair of ribs, hence called pseudoribs.
Myoglobin : A red colored pigment present in sarcoplasm of muscle.
Sarcomere : A portion of myofibril between two successive ‘Z’ lines.
Sarcocolema : The plasma membrane of a muscle.
Gout : Inflammation of joints due to accumulation of uric acid crystal.
Suture : immovable joints between skull bones.
Synovial joints : Freely movable joints between limb bones.
Patella : A seasmoid bone acting as kneecap.
Intervertebral disc : Fibro cartilaginous pad present between the vertebrae 
that act as shock absorbers.
Tendon—Connective tissue made of yellow fibrous tissue which connect 
muscle to bone. It is not flexible.
Ligament—Connective tissue made of white fibrous tissue which joins two 
bones. It is flexible.
L.M.M. : Light meromyosin
HMM : Heavy meromyosin
Types of Movement :
1. Amoeboid movement : These movements takes place in phagocytes
where leucocytes and macrophages migrate through tissue. It is affected by
pseudepodia formed by the streaming of protoplasm (as in amoeba)
2. Ciliary movement : These movement occurs in internal organs which are
lined by ciliary epithelium.
3. Muscular Movement : This movements involve the muscle fibers, which
have the ability to contract and relex.
Properties of Muscle : (i) Excitability  (ii) Contractility
(iii) Extensibility   (iv) Elasticity
Types of Muscles :
 (a) Skeletal muscles or striated muscles—These involved in locomotion and 
change of body postures. These are also known as voluntary muscles.
 (b) Visceral muscles or smooth muscles—These are located in inner wall of 
hollow visceral organ, smooth in appearance and their activity are not under 
control of voluntary nervous system. They are called involuntary muscles.
 (c) Cardiac muscles—The muscles of heart, involuntary in nature, striated and 
branched, These are uninucleated.
Characteristic Skeletal Muscle Smooth Muscle Cardiac Muscle
Location Muscles attached with muscles found in the inner wa- Muscles found only
skeletal components lls of hollow visceral organs in heart. 
Appearance Striated having light and unstriped, smooth in Striated in
dark bands. appearance with tapering appearance and
ends. branched
Control They are controlled by They are not under the not under the
our will hence called control of our will hence direct control of
voluntary muscles. called involuntary muscles. nervous system.
Structure of myofibril :
? Each myofibril consist of alternate dark and light band.
? Dark band—contain myosin protein and is called A-band or Anisotroic band.
? Light band—Contain actin protein and is called I Band or Isotropic band.
? I Band is bisected by an elastic fiber called ‘Z’ line. Actin filament (thin
filament) are firmly attached to the ‘Z’ lines.
? Myosin filament (thick filament) in the ‘A’ Band are also held together in
the middle of T Band by thin fibrous membrane called ‘M’ line.
? The portion between two successive ‘Z’ lines is considered as functional
unit of contraction and is called a sarcomere.
Page 3


Points To Remember
Arthritis : an inflammatory joint disease characterised by inflammation of 
joints.
Coccyx : tail bone formed by fusion of four coccygeal vertebrae in man.
Dicondylic Skull : A Skull with two occipital condyles.
Endo Skeleton : A skeleton present in side the body.
Fascicle : Bundles of muscles fibres held together by connective tissue.
Fascia : Collagenous connective tissue layer that surrounds muscle bundles.
Floating ribs : The ribs that remain free anteriorly, (last 2 pairs)
False ribs : 8th, 9th and 10th pair of ribs not directly joins the sternum but 
to seventh pair of ribs, hence called pseudoribs.
Myoglobin : A red colored pigment present in sarcoplasm of muscle.
Sarcomere : A portion of myofibril between two successive ‘Z’ lines.
Sarcocolema : The plasma membrane of a muscle.
Gout : Inflammation of joints due to accumulation of uric acid crystal.
Suture : immovable joints between skull bones.
Synovial joints : Freely movable joints between limb bones.
Patella : A seasmoid bone acting as kneecap.
Intervertebral disc : Fibro cartilaginous pad present between the vertebrae 
that act as shock absorbers.
Tendon—Connective tissue made of yellow fibrous tissue which connect 
muscle to bone. It is not flexible.
Ligament—Connective tissue made of white fibrous tissue which joins two 
bones. It is flexible.
L.M.M. : Light meromyosin
HMM : Heavy meromyosin
Types of Movement :
1. Amoeboid movement : These movements takes place in phagocytes
where leucocytes and macrophages migrate through tissue. It is affected by
pseudepodia formed by the streaming of protoplasm (as in amoeba)
2. Ciliary movement : These movement occurs in internal organs which are
lined by ciliary epithelium.
3. Muscular Movement : This movements involve the muscle fibers, which
have the ability to contract and relex.
Properties of Muscle : (i) Excitability  (ii) Contractility
(iii) Extensibility   (iv) Elasticity
Types of Muscles :
 (a) Skeletal muscles or striated muscles—These involved in locomotion and 
change of body postures. These are also known as voluntary muscles.
 (b) Visceral muscles or smooth muscles—These are located in inner wall of 
hollow visceral organ, smooth in appearance and their activity are not under 
control of voluntary nervous system. They are called involuntary muscles.
 (c) Cardiac muscles—The muscles of heart, involuntary in nature, striated and 
branched, These are uninucleated.
Characteristic Skeletal Muscle Smooth Muscle Cardiac Muscle
Location Muscles attached with muscles found in the inner wa- Muscles found only
skeletal components lls of hollow visceral organs in heart. 
Appearance Striated having light and unstriped, smooth in Striated in
dark bands. appearance with tapering appearance and
ends. branched
Control They are controlled by They are not under the not under the
our will hence called control of our will hence direct control of
voluntary muscles. called involuntary muscles. nervous system.
Structure of myofibril :
? Each myofibril consist of alternate dark and light band.
? Dark band—contain myosin protein and is called A-band or Anisotroic band.
? Light band—Contain actin protein and is called I Band or Isotropic band.
? I Band is bisected by an elastic fiber called ‘Z’ line. Actin filament (thin
filament) are firmly attached to the ‘Z’ lines.
? Myosin filament (thick filament) in the ‘A’ Band are also held together in
the middle of T Band by thin fibrous membrane called ‘M’ line.
? The portion between two successive ‘Z’ lines is considered as functional
unit of contraction and is called a sarcomere.
Structure of Actin and Myosin Filament
1. Actin 	 filament	 : An actin filament is made of two ‘F’ actins which are
helically wound to each other. Two filaments of tropo myosin protein also
run close to ‘F’ actins throughout its length. A complex protein Troponin is
distributed at regular intervals on tropomyosin which mask the actin binding
site for myosin.
2. Myosin 	 filament	 :	 Each myosin filament is a polymer of meromyosin.
Each meromyosin has  two components—a globular head with a short arm
and a tail. Head is made of heavy meromyosin while tail is made of light
meromyosin. The head with its short arm project outward at regular distance
and angle from each other and is known as cross arm. The head has an active
site for actin and binding site for ATP.
Red muscle fibres :
— These are red in colour due to presence of high content of myoglobin.
— These contain plenty of mitochondria.
— Sarcoplasmic reticulum is less in these fibres.
— Show slow but sustained contractions for longer periods.
Thick 
filament
Thin 
filament
I-Band
Page 4


Points To Remember
Arthritis : an inflammatory joint disease characterised by inflammation of 
joints.
Coccyx : tail bone formed by fusion of four coccygeal vertebrae in man.
Dicondylic Skull : A Skull with two occipital condyles.
Endo Skeleton : A skeleton present in side the body.
Fascicle : Bundles of muscles fibres held together by connective tissue.
Fascia : Collagenous connective tissue layer that surrounds muscle bundles.
Floating ribs : The ribs that remain free anteriorly, (last 2 pairs)
False ribs : 8th, 9th and 10th pair of ribs not directly joins the sternum but 
to seventh pair of ribs, hence called pseudoribs.
Myoglobin : A red colored pigment present in sarcoplasm of muscle.
Sarcomere : A portion of myofibril between two successive ‘Z’ lines.
Sarcocolema : The plasma membrane of a muscle.
Gout : Inflammation of joints due to accumulation of uric acid crystal.
Suture : immovable joints between skull bones.
Synovial joints : Freely movable joints between limb bones.
Patella : A seasmoid bone acting as kneecap.
Intervertebral disc : Fibro cartilaginous pad present between the vertebrae 
that act as shock absorbers.
Tendon—Connective tissue made of yellow fibrous tissue which connect 
muscle to bone. It is not flexible.
Ligament—Connective tissue made of white fibrous tissue which joins two 
bones. It is flexible.
L.M.M. : Light meromyosin
HMM : Heavy meromyosin
Types of Movement :
1. Amoeboid movement : These movements takes place in phagocytes
where leucocytes and macrophages migrate through tissue. It is affected by
pseudepodia formed by the streaming of protoplasm (as in amoeba)
2. Ciliary movement : These movement occurs in internal organs which are
lined by ciliary epithelium.
3. Muscular Movement : This movements involve the muscle fibers, which
have the ability to contract and relex.
Properties of Muscle : (i) Excitability  (ii) Contractility
(iii) Extensibility   (iv) Elasticity
Types of Muscles :
 (a) Skeletal muscles or striated muscles—These involved in locomotion and 
change of body postures. These are also known as voluntary muscles.
 (b) Visceral muscles or smooth muscles—These are located in inner wall of 
hollow visceral organ, smooth in appearance and their activity are not under 
control of voluntary nervous system. They are called involuntary muscles.
 (c) Cardiac muscles—The muscles of heart, involuntary in nature, striated and 
branched, These are uninucleated.
Characteristic Skeletal Muscle Smooth Muscle Cardiac Muscle
Location Muscles attached with muscles found in the inner wa- Muscles found only
skeletal components lls of hollow visceral organs in heart. 
Appearance Striated having light and unstriped, smooth in Striated in
dark bands. appearance with tapering appearance and
ends. branched
Control They are controlled by They are not under the not under the
our will hence called control of our will hence direct control of
voluntary muscles. called involuntary muscles. nervous system.
Structure of myofibril :
? Each myofibril consist of alternate dark and light band.
? Dark band—contain myosin protein and is called A-band or Anisotroic band.
? Light band—Contain actin protein and is called I Band or Isotropic band.
? I Band is bisected by an elastic fiber called ‘Z’ line. Actin filament (thin
filament) are firmly attached to the ‘Z’ lines.
? Myosin filament (thick filament) in the ‘A’ Band are also held together in
the middle of T Band by thin fibrous membrane called ‘M’ line.
? The portion between two successive ‘Z’ lines is considered as functional
unit of contraction and is called a sarcomere.
Structure of Actin and Myosin Filament
1. Actin 	 filament	 : An actin filament is made of two ‘F’ actins which are
helically wound to each other. Two filaments of tropo myosin protein also
run close to ‘F’ actins throughout its length. A complex protein Troponin is
distributed at regular intervals on tropomyosin which mask the actin binding
site for myosin.
2. Myosin 	 filament	 :	 Each myosin filament is a polymer of meromyosin.
Each meromyosin has  two components—a globular head with a short arm
and a tail. Head is made of heavy meromyosin while tail is made of light
meromyosin. The head with its short arm project outward at regular distance
and angle from each other and is known as cross arm. The head has an active
site for actin and binding site for ATP.
Red muscle fibres :
— These are red in colour due to presence of high content of myoglobin.
— These contain plenty of mitochondria.
— Sarcoplasmic reticulum is less in these fibres.
— Show slow but sustained contractions for longer periods.
Thick 
filament
Thin 
filament
I-Band
199
White muscle fibres
— These are pale or whitish due to presence of less content of myoglobin.
— These contain fewer mitochondria
— Sarcoplasmic reticulum is more/high
— During strenuous exercise, lactic acid accumulates in large quantity so muscle 
fatigues
Mechanism or Muscle contraction : Sliding filament theory
The contraction of muscle fiber takes place by the sliding of actin (thin 
filament) on myosin (thick filament)
? Muscle contraction is initiated by a signal sent by the CNS via a motor
neuron.
? Impulse from motor nerve stimulates a muscle fiber at neuro muscular
junctions.
? Neurotransmitter releases here which generates an action potential in
sarcolema.
? This causes release of Ca
++
 into sarcoplasm. These Ca
++
 binds with troponin,
thereby remove masking of active site.
? Myosin head binds to exposed active site on actin to form a cross bridge,
utilising energy from ATP hydrolysis.
? This pulls the acin filament towards the centre of ‘A’ band.
? ‘Z’ lines also pulled inward thereby causing a shortening of sarcomere i.e.
contraction.
? I band get reduced, whereas the ‘A’ band retain the length.
? During relexation,  the cross bridge between the actin and myosin break.
Ca
++
 pumped back to sarcoplasmic cisternae. Actin filament slide out of ‘A
band and length of I band increase. This returns the muscle to its original
state.
Page 5


Points To Remember
Arthritis : an inflammatory joint disease characterised by inflammation of 
joints.
Coccyx : tail bone formed by fusion of four coccygeal vertebrae in man.
Dicondylic Skull : A Skull with two occipital condyles.
Endo Skeleton : A skeleton present in side the body.
Fascicle : Bundles of muscles fibres held together by connective tissue.
Fascia : Collagenous connective tissue layer that surrounds muscle bundles.
Floating ribs : The ribs that remain free anteriorly, (last 2 pairs)
False ribs : 8th, 9th and 10th pair of ribs not directly joins the sternum but 
to seventh pair of ribs, hence called pseudoribs.
Myoglobin : A red colored pigment present in sarcoplasm of muscle.
Sarcomere : A portion of myofibril between two successive ‘Z’ lines.
Sarcocolema : The plasma membrane of a muscle.
Gout : Inflammation of joints due to accumulation of uric acid crystal.
Suture : immovable joints between skull bones.
Synovial joints : Freely movable joints between limb bones.
Patella : A seasmoid bone acting as kneecap.
Intervertebral disc : Fibro cartilaginous pad present between the vertebrae 
that act as shock absorbers.
Tendon—Connective tissue made of yellow fibrous tissue which connect 
muscle to bone. It is not flexible.
Ligament—Connective tissue made of white fibrous tissue which joins two 
bones. It is flexible.
L.M.M. : Light meromyosin
HMM : Heavy meromyosin
Types of Movement :
1. Amoeboid movement : These movements takes place in phagocytes
where leucocytes and macrophages migrate through tissue. It is affected by
pseudepodia formed by the streaming of protoplasm (as in amoeba)
2. Ciliary movement : These movement occurs in internal organs which are
lined by ciliary epithelium.
3. Muscular Movement : This movements involve the muscle fibers, which
have the ability to contract and relex.
Properties of Muscle : (i) Excitability  (ii) Contractility
(iii) Extensibility   (iv) Elasticity
Types of Muscles :
 (a) Skeletal muscles or striated muscles—These involved in locomotion and 
change of body postures. These are also known as voluntary muscles.
 (b) Visceral muscles or smooth muscles—These are located in inner wall of 
hollow visceral organ, smooth in appearance and their activity are not under 
control of voluntary nervous system. They are called involuntary muscles.
 (c) Cardiac muscles—The muscles of heart, involuntary in nature, striated and 
branched, These are uninucleated.
Characteristic Skeletal Muscle Smooth Muscle Cardiac Muscle
Location Muscles attached with muscles found in the inner wa- Muscles found only
skeletal components lls of hollow visceral organs in heart. 
Appearance Striated having light and unstriped, smooth in Striated in
dark bands. appearance with tapering appearance and
ends. branched
Control They are controlled by They are not under the not under the
our will hence called control of our will hence direct control of
voluntary muscles. called involuntary muscles. nervous system.
Structure of myofibril :
? Each myofibril consist of alternate dark and light band.
? Dark band—contain myosin protein and is called A-band or Anisotroic band.
? Light band—Contain actin protein and is called I Band or Isotropic band.
? I Band is bisected by an elastic fiber called ‘Z’ line. Actin filament (thin
filament) are firmly attached to the ‘Z’ lines.
? Myosin filament (thick filament) in the ‘A’ Band are also held together in
the middle of T Band by thin fibrous membrane called ‘M’ line.
? The portion between two successive ‘Z’ lines is considered as functional
unit of contraction and is called a sarcomere.
Structure of Actin and Myosin Filament
1. Actin 	 filament	 : An actin filament is made of two ‘F’ actins which are
helically wound to each other. Two filaments of tropo myosin protein also
run close to ‘F’ actins throughout its length. A complex protein Troponin is
distributed at regular intervals on tropomyosin which mask the actin binding
site for myosin.
2. Myosin 	 filament	 :	 Each myosin filament is a polymer of meromyosin.
Each meromyosin has  two components—a globular head with a short arm
and a tail. Head is made of heavy meromyosin while tail is made of light
meromyosin. The head with its short arm project outward at regular distance
and angle from each other and is known as cross arm. The head has an active
site for actin and binding site for ATP.
Red muscle fibres :
— These are red in colour due to presence of high content of myoglobin.
— These contain plenty of mitochondria.
— Sarcoplasmic reticulum is less in these fibres.
— Show slow but sustained contractions for longer periods.
Thick 
filament
Thin 
filament
I-Band
199
White muscle fibres
— These are pale or whitish due to presence of less content of myoglobin.
— These contain fewer mitochondria
— Sarcoplasmic reticulum is more/high
— During strenuous exercise, lactic acid accumulates in large quantity so muscle 
fatigues
Mechanism or Muscle contraction : Sliding filament theory
The contraction of muscle fiber takes place by the sliding of actin (thin 
filament) on myosin (thick filament)
? Muscle contraction is initiated by a signal sent by the CNS via a motor
neuron.
? Impulse from motor nerve stimulates a muscle fiber at neuro muscular
junctions.
? Neurotransmitter releases here which generates an action potential in
sarcolema.
? This causes release of Ca
++
 into sarcoplasm. These Ca
++
 binds with troponin,
thereby remove masking of active site.
? Myosin head binds to exposed active site on actin to form a cross bridge,
utilising energy from ATP hydrolysis.
? This pulls the acin filament towards the centre of ‘A’ band.
? ‘Z’ lines also pulled inward thereby causing a shortening of sarcomere i.e.
contraction.
? I band get reduced, whereas the ‘A’ band retain the length.
? During relexation,  the cross bridge between the actin and myosin break.
Ca
++
 pumped back to sarcoplasmic cisternae. Actin filament slide out of ‘A
band and length of I band increase. This returns the muscle to its original
state.
200
Vertebral formulae of man C
7
T
12
L
5
S
(5)
 C
(4)
 = 33
Human skeleton – 206 bones
       Axial skeleton (80 bones) Appendicular
skeleton (126 bones)
skull (29 bones) vertebrae (26) (33)             1
cranium-8 face-14 Cervical-7    stemum        Ribs
Ear ossicle-6 Thoracic-12        1    12 pairs (24)
Hyoid-1 Lumber-5
sacral-1 (5-fused to form 1 sacrum)
Caudal-1 (4-coccygeal fused to form 1 coccyx)
Girdles (6 bones)  Clavicle 2           Limbs (120 bones)
Pectoral (Shoulder girdle) 
Pelvic (Hip gridle(    (2) Scapula-2
Fore limbs (60 bones) - 30 in each limb Hind limbs (60) 30 in each limb
Humerus-2 Femur-2
Radius-2 Tibia-2
Ulna-2 Fibula-2
Carplas-16 Patella-2
Meta Carpals-10  Tarsals-14, Meta Tarsal-10
Phalanges-28=2× (2, 3, 3, 3, 3) Phalanges-28
Joints
 Fibrous joints Cartilaginous joints Synovial joints
do not allow allo very slight Freely
movement movement movable
e.g., joints between e.g., joint between
the bones of skull adjacent vertebrae
Ball and socket Hinge Pivot Gliding Saddle
Joints Joints Joints Joints Joints
e.g., between humerus e.g., knee e.g., Atlas e.g., between e.g., between
 and pectroal girdle Joint and axis carpals Carpals and meta
 between femur Elbow joint carpals of thumb
 and pelvic girdle