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LOCOMOTION AND �MOVEMENT

By :

Mrs. Sheela Jayakumar

(PGT Biology)

JNV LEPAKSHI

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INTRODUCTION

Movement of body parts and locomotion are two important properties of living organism.

Animals including human beings can move their body parts like limbs, jaws, eyelids, tongue etc.

Some movements results in a change of place or location of the organism; such voluntary movements are called locomotion.e.g., walking, running, climbing etc.

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TYPES OF CELLULAR MOVEMENT

AMOEBOID MOVEMENTs	CILIARY MOssVEMENT	MUSCULAR MOVEMENT
1.Some specialized cells like macrophages and leukocytes move by the formation of pseudopodia.	1. It occurs in most of the internal tubular organs, which are lined by ciliated epithelium.	1. The muscle shows special properties like excitability, contractility, extensibility and elasticity.
2. Such a movement occurs by streaming of the protoplasm (as in amoeba)	2. Passage of ova through female reproductive tract occur by ciliated epithelium	2. The muscles have been classifies using criteria like location, appearance and nature of regulation of their activities

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Types of muscles

Skeletal muscles

Visceral muscles

Cardiac muscles

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They are closely associated with the skeletal system of the body.

Muscle cells are cylindrical, unbranched and multinucleate.

They have a striped appearance hence called striated muscle.

Their activities are under voluntary control, hence are called voluntary muscles.

They are involved in locomotory action and changes of body posture.

Skeletal muscles

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They are located in the inner walls of hollow visceral organs of the body.

Muscle fibers are spindle shaped and uninucleate.

They do not have striation, hence are called smooth or non-striated muscles.

Their activities are not under voluntary control, hence are called involuntary muscles.

Visceral muscles

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They are present in the walls of the heart.

Many cardiac muscle cells assemble in a branching pattern to form a cardiac muscle.

The muscle fibers are uninucleate and have faint striation.

The fibers have intercalated discs.

They are involuntary as the nerves system does not control their activity directly.

Cardiac muscles

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1.Skeletal muscle is made of muscle bundles or fascicle

2.Fascicles are held together by a connective tissue layer called fascia.

3.Inside the fascicle present muscle fibres.

4. myofibrils are arranged in the form of filaments in the sarcoplasm of muscle fibre.

STRUCTURE OF SKELETAL MUSCLE

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5.Light bands of myofibrils contain actin and dark bands contain myosin protein.

6.In the Centre of actin lies elastic fibre called Z-line and M-line in the myosin.

7.The portion of myofibril between two Z-line is called sarcomere.

8.The middle part of the myosin is not overlapped by actin filament is called H-zone.

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ACTIN ( thin filament)

Each actin filament is made up of three types proteins namely F- actin, tropomyosin and troponin.

Each F-actin is a polymer of monomeric G-globular actins.

Two F-actins are helically wound to each other, two filaments of tropomyosin also run close to the F-actin along their length.

Troponin, a complex protein is present at regular intervals on the tropomyosin.

Troponin masks the binding site of myosin.

STRUCTURE OF CONTRACTILE PROTEINS:

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STRUCTURE OF MYOSIN PROTEINS:

Myosin is a polymer of monomeric proteins called meromyosins.

It has two important parts, a globular head with a short arm and a tail.

The head is called the heavy meromyosin(HMM), and tail is called the light meromyosin(LMM).

The HMM component projects outwards from the surface of the meromyosin, and is called cross arm.

The globular head functions as ATPase enzyme and has binding sites for ATP and active site for actin.

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MECHANISM OF MUSCLE CONTRACTION

The mechanism of muscle contraction is explained by the sliding filament theory.

When a neural signal reaches the neuromuscular junction, it releases a neurotransmitter, which generates an action potential in the sarcolemma.

The action potential spreads through the muscle fiber and causes the release of Ca²⁺ions from sarcoplasmic reticulum into the sarcoplasm.

The Ca²⁺ions bind to the subunit of troponin of actin filament and thereby remove the masking of the active sites for myosin.

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The myosin head binds to the active sties on actin to form a cross bridge; this utilizes energy from the hydrolysis of ATP.

This pulls the actin filament towards the center of A-band.

As a result, the Z-line limiting the sarcomere are pulled closer together, causing the shortening of the sarcomere i.e. the contraction of the muscle.

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TYPES OF MUSCLE FIBER

RED MUSCLE

WHITE MUSCLE

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RED MUSCLE

They are red in colour due to the presence of high content of myoglobin.

They contain a plenty of mitochondria.

These muscles are called aerobic muscles.

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WHITE MUSCLE

They are white in colour due to the presence of less content of myoglobin.

They contain a less mitochondria.

These muscles are called anaerobic muscles.

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Skeletal system consists of a framework of bones and few cartilages.

The functions of skeletal system.

It protects the vital organs of the body.

It plays a vital role in movement and locomotion.

It serves as reservoir of many minerals like calcium and phosphate.

SKELETAL SYSTEM

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DIVISION OF SKELETON

Axial skeleton

Appendicular skeleton

Skull
Vertebral column
Sternum
Ribs

Limbs
Girdles

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SKULL

Skull is composed of two sets of bones

i. Cranial bones- 8

ii. Facial bone- 14

A single U-shaped bone called hyoid is present at the base of the buccal cavity.

Each middle ear contains 3 tiny bones: Malleus, Incus and Stapes collectively called Ear ossicles.

The skull region articulates with the superior region of the vertebral column with the help of two occipital condyles.

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VERTEBRAL COLUMN

The unit of vertebral column is vertebrae(26).

It extends from the base of the skull and constitute the main frame of the trunk.

It has central hollow portion through which the spinal cord passes.

The vertebral column is differentiated into:

i. Cervical-7

ii. Thoracic-12

iii. Lumbar-5

iv. Sacral-1

v. Coccygeal-1

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RIBS

Each rib is a thin flat bone.

First 7 pairs of ribs are called true ribs.

The 8^th, 9^th, and 10^th are called flase ribs.

Last two pairs(11^th and 12^th) are called floating ribs.

Totally there are 12 pairs of ribs.

The sternum is a flat bone on the ventral mid line of thorax.

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BONES OF FORELIMB

Each forelimb consists of 30 bones.

Humerus-1

Radius and Ulna- 2

Carples-8

Metacarples-5

Phalanges-14

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LOWER LIMB

Each lower limb consists of 30 bones.

Femur-1

Tibia and Fibula-2

Tarsals-7

Metatarsals-5

Phalanges-14

Patella-1

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PELVIC GIRDLE

PECTORIAL GIRDLE

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JOINTS

Joints are points of contact between two or more bones or between a bone and a cartilage.

Joints are essential for all types of movements involving the boney parts of the body

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CLASSIFICATION OF JOINTS

Fibrous joints

Cartilaginous joints

Synovial joints

Do not allow any movement.
Ex: Flat skull bones

Allows limited movement.
Ex: Joints between adjacent vertebrae.

Freely movable.

Ball and socket

Hinge joint

Pivot joint

Gliding joint

Saddle joint

Ex: Between humerus and pectoral girdle.

Ex: Knee joint.

Ex: Between atlas and axis vertebrae.

Ex: Between carpals.

Ex: Between carpal and metacarpal of thumb.

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DISORDERS OF MUSCULAR AND SKELETAL SYSTEM

Myasthenia gravis: Auto immune disorder affecting neuromuscular junction leading to fatigue, weakening and paralysis of skeletal muscle.

Muscular dystrophy: Progressive degeneration of skeletal muscle, mostly due to genetic disorder.

Tetany: Wild contractions in muscle due to low calcium in body fluid.
Arthritis: Inflammation of joints.

Osteoporosis: Age-related disorder characterized by decreased bone mass and increased chances of fractures.

Gout: Inflammation of joints due to accumulation uric acid crystals.