namma kalvi 11th bio-zoology chapter 9 study material em...1. hydrostatic skeleton 2. exoskeleton...

__ 11th BIO-ZOOLOGY CHAPTER-9 (C. KARUNAKARAN. M.Sc., M.Phil., PhD

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11TH BIO-ZOOLOGY UNIT- 4 STUDY MATERIAL

9. LOCOMOTION AND MOVEMENT

Locomotion:

✓ Movement of the organism from one place to another is called locomotion.

Uses of locomotion

✓ Search for food ✓ Shelter mating (reproduction) ✓ To escape from the predator ✓ Locomotion has evolutionary significance and etc.…

Types of movement:

The different types of movements that occur in the cells of our body. 1. Amoeboid movement:

• The movement by means pseudopodium is called amoeboid movement. • Amoeboid movement characteristic feature of an amoeba. • Pseudopodium is a temporary projection of cytoplasm formed on the body to

protect pathogens. • It occurs in macrophages.

2. Ciliary movement:

• Ciliary movement occurs in the respiratory passages and genital tract. • It is made of ciliated epithelial cells.

3. Flagellar movement:

• Flagellar movement is the swimming brought about by the beating of flagella. • The sperm cells show flagellar movement.

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4. Muscular movement:

• This type of movement occurs in the muscle cells so it is called muscular movements.

• E.g. the movements of hand, legs, jaws, and tongue etc.….

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Muscular systems:

Types of muscles:

▪ Muscles are specialized tissues which are derived from the embryonic `mesoderm’s`

▪ Muscles are made of a group of cells called `myocytes`. ▪ Muscle is a soft tissue found in most of the animals. ▪ The study of tissue is called `Histology`.

Types:

The muscle is classified into three types, based on the locomotion.

1. Skeletal muscles (Striated muscles)

Skeletal muscle is closely associated with skeletal components. So it is called skeletal muscles.

These muscles are exhibit striation so it is also called `striated muscles` They are voluntary in nature.

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2. Visceral muscle (Striated muscles)

Visceral muscles are located in the inner walls of hollow visceral organs of the body like an alimentary canal, and reproductive tract etc...

They do not exhibit any striation. So they are called smooth muscles or non-striated muscles.

3. Cardiac muscles

Cardiac muscles are the muscles of the heart. It is striated and voluntary in nature.

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Types of skeletal muscle contraction:

The process by which muscles are shortening is termed `muscle contraction` They are two types of muscle contractions namely isometric and isotonic

contraction.

1. Isometric contraction:

Iso - same

Metric - Length

A contracting muscle retains its original length so this type of contraction is called an isometric contraction.

E.g pushing against a wall, holding a heavy bag etc…

2. Isotonic contraction:

Iso - same

Tonic – tension

The muscle is able to move a load and it shortens during a contraction so it is called `isometric contraction`

E.g the body muscle help in the process of walking.

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Types of skeletal muscle fibers:

The skeletal muscle fibers are classified as different types.

Based on

Rate of shortening Either fast or slow ATP needed for contraction and Either oxidative or glycolytic.

1. Red / slow:

Type I fibers – slow twitch fibers

2. Red / fast:

Type II a fibers – fast oxidative fibers or termed as red muscle fibers.

3. White / fast:

Type II b fibers – fast glycolytic fibers or termed as white muscle fibers.

a) Oxidative fibers

Oxidative fibers primarily use oxidative phosphorylation. The oxidative fibers are termed as `red muscle fibers`

b) Glycolytic fibers (GF)

Large stores of glycogen are called glycolytic fibers. Gf –are termed as white muscle fibers because there is myoglobin are absent

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Mechanism of muscle contraction:

Mechanism of muscle contraction is processed by which muscle are shortening is termed `muscle contraction`

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

This theory was proposed by Huxley, Andrew F. and Rolf Niedergerke in 1954-1957

Mechanisms:

An action potential is originating in the central nervous system (CNS) and reach as to the alpha motor neuron.

The junction between an alpha motor neuron and sarcolemma of the muscle fibers is called neuromuscular junction (JMN) or motor end plate.

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The signal reaching this junction releases a chemical called acetylcholine. It leads to the depolarization of the motor end plate.

Utilizing the energy from ATP hydrolysis, the head of the myosin bind active sites on actin and form a cross bridge and causes of muscle contraction.

The ATP molecule split again and myosin head is reactive for the next cycle to begin.

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Structure of contractile proteins:

o Contraction of the muscle depends on the presence of contractile proteins such as actin and myosin in the myofilaments.

o Each myosin molecule is made up of a monomer called meromyosin. o Meromyosin: (two regions)

a) Short arm-Heavy meromyosin (HMM)

b) Tail portion- Light meromyosin (LMM)

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Skeletal functions its function:

• The skeletal system is constituted by a framework of bones and cartilages. It is derived from the embryonic mesoderm.

• Muscles are attached to the bones by means of tendons and provide the necessary force required for the bones of the skeleton to operate as levers.

• There are three types’ of skeletal systems. They are,

1. Hydrostatic skeleton 2. Exoskeleton and 3. Endoskeleton

▪ In human beings, the skeletal system is made up of 206 bones and cartilages. It is grouped into two principal divisions – the axial skeleton and the appendicular skeleton.

▪ The axial skeleton consists of 80 bones and the appendicular skeleton consists of 126 bones

Functions:

1. Supports surrounding tissues (Total body) 2. Protects vital organs and soft tissues. 3. Manufactures blood cells. 4. Stores minerals & salts 5. Locomotion- It acts as a liver along with the muscles attached to it.

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Parts of skeletal muscles:

Each muscle cell is called ‘muscle fibers’ Each muscle fiber is surrounded by ‘endomysium’ A group of muscle fibers bundled together by collagen to form fasciculi or

fascicle. Each fascicle is surrounded by perimysium. All the fascicle collectively from the muscle belly. Each muscle belly is

surrounded by a connective layer called epimysium.

The plasma membrane of the muscle fiber is called sarcolemma and the cytoplasm is called sarcoplasm.

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The sarcoplasm contains numerous protein filaments are called myofibrils. Each myofibril contains thin filament actin and thick filament myosin. Myofibrils are surrounded by a network of tubules and channels called

sarcoplasmic reticulum. The calcium stored in this area.

Actin

▪ Actin is a muscle protein. ▪ It is present in the thin filament of muscles. ▪ It is a fibrous protein ▪ It is an insoluble protein. ▪ It exists in two forms, namely G-actin and F-actin. ▪ The formation of F-actin from G-actin is called polymerization. ▪ Polymerization requires salts and ATP. ▪ During muscle contraction, actin combines with myosin to form actomyosin.

Actin + myosin → Actomyosin

Myosin

▪ Myosin is a muscle protein. ▪ It is present in the thick filaments brings about the contraction. ▪ It is a fibrous protein. ▪ It is an insoluble protein. ▪ It consists of a rod-like tail, a neck, and a head. ▪ When myosin is treated with trypsin (enzyme). It is split into two components,

namely light meromyosin and heavy meromyosin.

Tropomyosin and troponin:

➢ Tropomyosin and troponin are the two main proteins that regulate actin and myosin interactions.

➢ Tropomyosin is a long strand that twisted around F-actin filaments and prevents muscle contraction.

➢ Troponin is distributed in regular intervals on the surface of tropomyosin.

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Structure of Sarcomere:

• A sarcomere is the basic unit of skeletal muscle tissue. • It is made of central dark band and two half - light bands.

• The light band contains actin and it is called I band or isotropic band. • The dark band contains myosin and it’s called A band or anisotropic band. • The actin is a thin filament and myosin is a thick filament.

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Human skeletal system:

In human beings, the skeletal system is made up of 206 bones and cartilages.

It is grouped into two principal divisions.

They are,

1. Axial skeletal and (consist of 80 bones)

2. Appendicular skeleton (consist of 126 bones)

1. Axial skeletal and (consist of 80 bones)

Axial skeleton forms the main axis of the body. It consists of the skull, hyoid bone, vertical column, and thoracic cage.

a) Skull:

The skull is composed of two sets of bones

a) Cranial bones and

b) Facial bones (consistn14 bones)

The cranial bones form the hard protective outer covering of the brain is called the brain box.

The capacity of the cranium is 1500 cm3

The upper jaw is formed of the maxilla.

The lower jaw is formed of the mandible.




b) Hyoid bone:

o The hyoid bone is a U-shaped bone present at the base of the buccal cavity. o It is the only one bone without joints.

o It is movable bone. o It is connected to the cranium.

c) Vertibral column (consist 33 bones)

The vertibral column is also called the backbone.

The vertebral column has five major regions.

They are,

Vertebral column

1. Cervical 2. Thoracic 3. Lumbar 4. Sacrum and 5. Coccyx

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Atlas and axis

The first vertebra is called the atlas and the second vertebra is called the axis.

The Sternum (chest bone 1)

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

It provides space for the attachment of the thoracic ribs and abdominal muscle.

d) The rib cage (consist of 24 bones)

There are 12 bones pairs of ribs. Each rib is a thin flat bone connected dorsally to the vertebral column. It has two articulation surfaces on its dorsal end, hence called ‘bicephalic’ The first seven pairs of ribs called true ribs or vertebra-sternal rib. Rib cage protects the lungs, heart liver and also plays a role in breathing.

2. The appendicular skeleton.

The bones of the upper their girdles constitute the appendicular skeleton.

The appendicular skeleton is composed of 126 bones.




a) The pectoral girdle or shoulder girdle

The pectoral girdle is a set of bones in the appendicular skeleton.

The pectoral girdle consists of a clavicle or collarbone and a scapula.

The upper limbs are attached to the pectoral girdles.

Acromion:

The acromion is a bony process.

Together with the coracoid process, it extends laterally over the shoulder joint.

Glenoid cavity or fossa;

Below the acromion is a depression is called the glenoid cavity.

The upper limb:

The upper limb consists of 30 separate bones and is specialized for mobility.

The skeleton of the arm, the region between the shoulder and elbow is the humans.

b) The pelvic girdle

✓ The pelvic girdle is a heavy structure specialized for weight bearing. ✓ It is composed of two hip bones called coxal bones.




The lower limb

The lower limb consists of 30 bones which carry the entire weight of the erect body and is subjected to exceptional forces when we jump or run.

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Joints:

A joint, or articulation, is the place where two bones come together.

Fibrous- Immovable: connect bones, no movement. (Skull and pelvis).

Cartilaginous- slightly movable, bones are attached by cartilage, a little movement (spine or ribs).

Synovial- freely movable, much more movement than cartilaginous joints. Cavities between bones are filled with synovial fluid. This fluid helps lubricate and protect the bones.

Types of bone cells

1. Osteocytes

Mature bone cells

2. Osteoblasts

Bone-forming cells

3. Osteoclasts

Bone-destroying cells

Break down bone matrix for remodeling and release of calcium

Bone remodeling is a process by both osteoblasts and osteoclasts.

Disorders of muscular system:

o Myasthenia gravis o Tetany o Muscle fatigue o Atrophy o Muscle pull o Muscular dystrophy

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Disorders of skeletal system:

1. Arthritis - Inflammation of the joints

▪ Osteo arthritis ▪ Rheumatoid arthritis ▪ Gouts arthritis or gout

2. Osteoporosis

▪ Joint damage that occurs when articular cartilage softens & breaks down = pain, stiffness, & restricted movement

▪ Causes include: aging, irritation, wear & abrasion of joints ▪ Most common type of chronic arthritis ▪ Frequently affects fingers, spine, knees & hips

3. Osteomyelitis

Infection of the bone

Causes include: invading bacteria, pneumonia, typhoid, inflammation of teeth, and injury to bone

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namma kalvi 11th bio-zoology chapter 9 study material em...1. hydrostatic skeleton 2. exoskeleton...

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