7-STRUCTURAL ORGANIZATION IN ANIMALS

CHAPTER NO.7 STRUCTURAL ORGANIZATION IN ANIMALS

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An epithelium is a tissue composed of one or more layers of cells covering the external and internal surfaces of various body parts. Epithelial tissue also forms glands.The term “epithelium” was given by a Dutch anatomist Ruysch to refer to the

fact that epithelial tissues grow upon other tissues.

LOCATION Cover exposed surfaces Forms inner lining of body cavities Lines hollow organs

Produces glandular secretions Epithelial tissues evolved first and are also formed first in the embryo. The epithelial tissues arise from all the three primary germ layers: ectoderm,mesoderm and endoderm of the embryo.

CHARACTERISTICS Cover all body surfaces, line organs, are major tissues of glands

One side is exposed to open space; underside is attached to connective tissue by a thin, non-cellular basement membrane

Lack blood vessels, fed by diff usion from well vascularized connective tissues

Reproduce rapidly Tightly packed

Good barriers: Skin, lining of mouth

Involved in secretion, absorption, excretion, sensory reception.There are two types of epithelial tissues namely:

1. SIMPLE EPITHELIUM

2. COMPOUND EPITHELIUM

SIMPLE EPITHELIUM It is composed of a single layer of cells and function as a lining for body cavities, ducts and tubes.

On the basis of structural modifications of the cells, simple epithelium is further divided into three types:One layer, cells are thin, flattened.Broad, disc shaped prominent central nuclei.Things pass through these easily by diffusion or filtration.Cells are bind with neighboring cells.It is also called pavement membrane due to its tile-like appearance.Easily damaged.

One layer, cube shaped cells Central, spherical nucleus Covers ovaries, kidney tubules, glandular ducts (salivary, thyroid,pancreas, liver) Secretion (in glands and secretion of gastric juices)Absorption (kidneys)

Elongated, slender pillar like cells, one layer Oval nuclei located near basement membrane on about the same level Line uterus, most organs of digestive tract(intestinal lining) Thick, protective of underlying structures

Secretes digestive fluids, absorbs nutrients Can have microvilli Can have goblet cells embedded, secrete mucus onto surface

iv. CILIATED EPITHELIUM Cilia are present on the free surface of columnar or cuboidal

cells.Present on the inner surface of hollow organs like bronchioles and fallopian tubes.Cilia can move, and their movement pushes substances like mucus forward to clear it from the ducts. The beating of the cilia moves solid dust particles in one direction through ducts.

v. GLANDULAR EPITHELIUM Some columnar and cuboidal cells get specialised for secretion Unicellular ; consisting of isolated glandular cells( globlet cells of

the alimentary canal) Multicellular; consisting of cluster of cells (salivary glands) On the basis of mode of pouring of their secretions, glands are exocrine and endocrine glands.

COMPOUND EPITHELIUM It is composed of more than one layer of cells and has limited secretion in secretion and absorption. Due to the appearance of stratified; hence it is known as stratified epithelial cells.

FUNCTION Provide protection against chemical and mechanical stresses Cover dry surface of the skin,The moist surface of buccal cavity, pharynx, inner lining of ducts of salivary glands and pancreatic ducts.

All cells in epithelium are held together with little intercellular material.Specialised junctions provide both structural and functional links between

its individual cells. Three types of cell junctions are found in the epithelium

and other tissues.

LET US KNOW WHAT WE HAVE LEARNT!

PART-A [VERY SHORT ANSWER TYPE QUESTIONS]

|. Multiple choice questions:

1. Which one of the following types of cell is involved in making of

the inner walls of large blood vessels?

a) Cuboidal epithelium

b) Columnar epithelium

c) Squamous epithelium

d) Stratified epithelium

2. The moist surface of the buccal cavity has:

a) Glandular epithelium

b) Ciliated epithelium

c) Compound epithelium

d) Columnar epithelium

3. The ciliated columnar epithelium is present in:

a) Bronchioles and fallopian tube

b) Bile duct and oesophagus

c) Fallopian duct and urethra

d) Eustachian tube and stomach lining

4. Gap, tight and adhering junctions are found in:

a) Epithelial tissue

b) Connective tissue

Cc) Muscular tissue

d) Neural tissue

5. Tissues having very less or no intercellular matrix is:

a) Epithelial

b) Muscular

c) Connective

d) Cardiac

ll. Fillin the blanks:

1. Simple cuboidal epithelium is found in for absorption.

2. types of cells line blood vessels.

3. The shape of cells of columnar epithelium is .

lll. True/False

1. Epithelial tissues help in secretion, absorption, excretion, sensory reception.

2. Glandular epithelium helps in secretion.

PART-A [ANSWER KEY]

I. MULTIPLE CHOICE QUESTIONS:

1. c) Squamous epithelium ( As they are thin and provide easy passage

for diffusion.)

2. c) Compound Epithelium (to provide protection from wear and tear)

3. a) Bronchioles and fallopian tubes(cilia help in the movement of material in one direction only)

4. a) Epithelial tissue(Specialised junctions provide both structural and

functional links between its individual cells)

5. a) Epithelial tissue(Characteristic feature of epithelial tissue)

ll. FILL IN THE BLANKS:

1. The lining of kidneys

2. Squamous epithelium

3. Elongated

lll. STATE TRUE OR FALSE:

1. True

2. True

PART-B [SHORT ANSWER TYPE QUESTIONS]

1. Name the tissue that lines the intestine internally. State its advantages.

2. State differences between simple and compound epithelium.

3. What are Cel! Junctions? Give its different types.

PART-C [LONG ANSWER TYPE QUESTION]

1. Describe various types of epithelial tissues with the help of labelled

diagrams.

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INRODUCTION:Dear students, Today we will study about connective tissues, there types

and functions.

TISSUES :- Tissues are groups of cells that have a similar structure and act together to perform a specific function.There are mainly four different types of tissues present in our body.

1. EPITHELIAL - provides covering or lining

2. MUSCULAR - helps in movement

3. NEURAL -responds to stimuli

4. CONNECTIVE - supports, links and cushions

What is Connective Tissue?

Connective tissues, as the name implies, support and connect different tissues and organs of the body. They are widely distributed in every part of the body. They originate from the mesoderm (the middle germinal layer of the embryo). Connective tissue is made up of a few cells present in the intercellular framework of protein fibres secreted by the cells, known as

collagen or elastin. The cells also secrete a thin gel of polysaccharides,which together with fibres make matrix or ground substance. The elasticity,flexibility and strength of the connective tissues are due to fibres. The function and types of connective tissues depend on the nature of the intercellular substance present.

Collagen fibres are the most widespread and made up of fibrous protein,collagen. Collagen fibres are flexible and have high tensile strength (comparable to steel).

Elastic fibres form a network and can be stretched like a rubber band.They are made up of protein elastic. They retain their original shape and size once the force is removed.Reticulate fibres consist of collagen and glycoproteins. They are thin

and form a delicate network. They join connective tissues to neighbouring

tissues.There are various kinds of cells present in different types of connective tissues. They secrete different types of fibres and matrices.Fibroblasts or adipose cells are stationary and macrophages, mast cells,monocytes, lymphocytes are migrating cells.

TYPES OF CONNECTIVE TISSUE :

Broadly connective tissues of animals are divided into three types:

1. PROPER CONNECTIVE TISSUE

2. SUPPORTIVE CONNECTIVE TISSUE

3. FLUID CONNECTIVE TISSUE

Fibroblasts are present in all connective tissue proper.Fibrocytes, Adipocytes, and Mesenchymal cells are fixed cells,which means they remain within the connective tissue. Other cells move in and out of the connective tissue in response to chemical

signals.Macrophages, mast ells,lymphocytes, plasma cells, and phagocytic cells are found in connective tissue proper but are

actually part of the immune system protecting the body.

It is further divided into two types:

1. LOOSE CONNECTIVE TISSUE

2. DENSE CONNECTIVE TISSUE

1. LOOSE CONNECTIVE TISSUE:

It is further of two types:

A) AREOLAR TISSUE

B) ADIPOSE TISSUE

A) AREOLAR TISSUE :

AREOLAR TISSUE:Areolar tissue shows relatively little specialization and is the most widely distributed connective tissue in the body. It contains all the cell types and fibers previously described and is structured in an apparently random, web-like fashion.FUNCTIONS: It fills the spaces between muscle fibers, surrounds blood and lymph vessels, and supports organs in the abdominal cavity. Areolar tissue underlies most epithelia and represents the connective tissue component of epithelial membranes.

B) ADIPOSE TISSUE:Adipose tissue consists mostly of fat storage cells, with little

extracellular matrix. A large number of capillaries allow rapid storage and

mobilization of lipid molecules. White adipose tissue is most abundant. It

can appear yellow and owes its color to carotene and related pigments from

Plant food.

FUNCTIONS:White fat contributes mostly to lipid storage and can serve as insulation

from cold temperatures and mechanical injuries. White adipose tissue can be

found protecting the kidneys, cushioning the back of the eye, within the abdomen, and in the hypo-dermis. Brown adipose tissue is more common in infants, hence the term "baby fat.Brown adipose tissue is thermogenic,meaning that as it breaks down fats, it releases metabolic heat, rather than producing adenosine triphosphate (ATP), a key molecule used in metabolism.

2. DENSE CONNECTIVE TISSUE :Dense connective tissue contains more collagen fibers than does loose connective tissue. As a consequence, it displays greater resistance to stretching and a higher tensile strength.There are three major categories of dense connective tissue:

REGULAR, IRREGULAR, and ELASTIC.Dense regular connective tissue fibers are parallel to each other,enhancing tensile strength and resistance to stretching in the direction of the fibre orientations.Ligaments and tendons are mostly formed from dense regular connective tissue.

A)TENDONS: A tendon is a fibrous connective tissue which attaches muscle to bone. Tendons may also attach muscles to structures such as the eyeball. A tendon serves to move the bone or structure.

B) LIGAMENTS: A ligament is a fibrous connective tissue which attaches bone to bone, and usually serves to hold structures together and keep them stable.

C) White Fibrous Tissue :The main constituent of white fibrous connective tissue is the protein collagen. White fibrous tissue is dense regular connective tissue that has a silvery white colour/appearance and is physically

tough, yet pliable. It consists of fibroblasts interspersed among many collagen fibres which are often aligned in the same direction,forming a mechanically strong structure.

FUNCTIONS:White fibrous tissue connects structures that require a mechanically

strong bond. The main functions of white fibrous tissue involve supporting

and protecting the surrounding structures.Supportive connective tissue includes the BONES and CARTILAGE.They are strong and durable tissues, that serve as supportive structures for other types. Bones are protective structures for critical organs like the brain,spinal cord, heart and lungs. Bones are very strong and durable but relatively inflexible. It is of following types:

A) BONES: Bones are rich in collagen fibres and calcium, which give strength. The cells of the bone are known as osteocytes. They are present in lacunae and secrete the matrix. There is substantial blood supply in bony tissues.Spongy bone is present in the core surrounded by the compact bone.

Osteons is the spindle-shaped unit present in the compact bone. Osteocytes are present in the concentric layers of the matrix in each osteon, called lamellae.There is a central marrow cavity made up of spongy tissues (marrow).The yellow marrow contains fat, whereas red marrow produces blood cells.

FUNCTIONS:Bones have many functions. They support the body structurally,protect our vital organs, and allow us to move. Also, they provide an environment for bone marrow, where the blood cells are created, and they act as a storage area for minerals, particularly calcium.

B) CARTILAGE:Cartilage is mostly present in the embryonic stages and works as a

supporting skeleton. Most of the cartilage is replaced by bones in adults.

However, it supports some structures in adults too. In humans,cartilage is present between the bones of the vertebral column, in the

external ear, nose and hands. The cartilage consists of chondrocytes cells,which are enclosed in a hard, rubbery matrix secreted by them. They secretecollagen fibres also, which provide additional strength.

Functions:Cartilage is a flexible connective tissue that keeps joint motion fluid by coating the surfaces of the bones in our joints and by cushioning bones

against impact. It is not as rigid as bone, but is stiffer and less flexible than

muscle tissue.Blood and lymph are fluid connective tissues. Cells circulate in a liquid extracellular matrix. The formed elements circulating in blood are all derived from hematopoietic stem cells located in bone marrow.Erythrocytes (red blood cells), transport oxygen and some carbon dioxide.

A) BLOOD: Blood is a type of fluid connective tissue made up of various

cells present in the plasma. The blood contains red blood cells (RBCs), white

blood cells (WBCs) and platelets.

FUNCTIONS :RBCs have haemoglobin and transport oxygen.WBCs form a defence system and protect from foreign antigens.

Platelets are important for blood clotting.

Plasma contains proteins, water, hormones, salts, etc. to transport to different parts of the body.

B) Lymph:Lymph drains into the blood and transports absorbed fat to the blood,

which cannot enter the bloodstream directly. Lymph has white blood cells in

the liquid matrix. They help in getting rid of toxins and waste materials. They

contain WBCs, which help in fighting infection.

LET US KNOW WHAT WE HAVE LEARNT!

A)MULTIPLE CHOICE QUESTIONS:

1. Under the microscope, a tissue specimen shows cells located in spaces scattered in a transparent background. This is probably

a) Loose connective tissue

b) bone

c) hyaline cartilage

d) tendon

2. Which connective tissue specializes in storage of fat?

a) dense connective tissue

b) tendon

C) adipose tissue

d) reticular tissue

3. Ligaments connect bones together and withstand a lot of stress.What type of connective tissue should you expect ligaments to contain?

a) dense irregular connective tissue

b) areolar tissue

c) dense regular connective tissue

d) adipose tissue

4. In bone, the main cells are

a) fibroblast

b) condroblast

c) lymphocytes

d) osteocytes

5. Connective tissue is made of which three essential components?

a) Cells, ground substance, and protein fibers

b) Matrix, ground substance, and fluid

c) Cells, ground substance, and carbohydrate fibers

d) Collagen, ground substance, and protein fibers

B) Fill ups

1. Areolar tissue is a................... connective tissue.

2. In comparasion to human erythrocytes, frogs erythrocytes are.................

3. Tips of the nose and external ears are ...............

C) True /false

1. collagen is globular protein.

2.Ligament is modified white fibrous tissue.

3. Histamine is secreated by histiocytes.

A) MULTIPLE CHOICE QUESTION

Ans 1. c) hyaline cartilage

Ans 2. c) adipose tissue

Ans 3. c) dense regular connective tissue

Ans 4. d) osteocytes

Ans 5. a) Cells, ground substance, and protein fibers

B) FILL UPS

1. loose

2. nucleated and with haemoglobin

3. cartilage

C) TRUE/FALSE

1. False (fibrous protein)

2. False (modified yellow elastic fibrous tissue)

3. False (mast cells)

1. Write a short note on Areolar tissue.

2. Differentiate between tendon and ligament.

3. Differentiate between bone and cartilage.

4. Discuss various functions of blood in animals.

1. Discuss in detail supportive connective tissue its types and functions.

2. Discuss in detail fluid connective tissues, its types and functions.

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INTRODUCTION:Dear student, till now we have studied about Epithelial and Connective tissues and their types. Today we will study about a Movement is one of the most important characteristics of living organisms. Non-living objects do not move. The movement of non-living organisms is induced while of living organisms are autonomic (self-sustained).

BASIC TYPES OF MOVEMENTS:Amoeboid. It is typical of Amoeba. It helps in food capture and change of place. This type of movement is found in leucocytes.Ciliary Movement. |t is characteristic way of ciliated protozoans such as Paramecium. Cilia of feeding apparatus of Paramecium drive water and food. The cilia of Fallopian tubes and vasa efferentia of human females and males, transport ova and spermatozoa, respectively.Muscular Movement. This basic mechanism is used in the majority of

vertebrates, including humans. The universal property of this mechanism is to exert a force by alternate contraction and relaxation.Locomotion in Humans .Locomotion in Humans depends on the movement of muscle fibres. Skeleton and joints also help in locomotion.

MUSCLES:In humans muscles constitute about 40-50 percent of the total body weight. These muscles are broadly classified into three categories:

1. Skeletal or Striped or Voluntary muscles

2. Smooth or Unstriped or Involuntary muscles

3. Cardiac or heart muscles

SKELETAL MUSCLES. These muscles are found in the limbs, body wall, tongue,pharynx and beginning of oesophagus. These muscles are under the control of animals will. These muscles are normally attached to the skeleton. Potassium is the most abundant mineral element in muscles. Muscles store glycogen. They have oxygen carrying pigment MYOGLOBIN. Muscles contain ATP, Creatinine,Phosphocreatinine, Urea etc.

SMOOTH MUSCLES: These are found in posterior part of oesophagus, stomach.

intestine. lungs. urinary bladder, blood vessels. iris of eyes, dermis of skin and

arrector pili muscle of hair. Smooth muscles are never connected with skeleton.

Action of these muscles is controlled by autonomic nervous system and hence they

are NOT under the control of the animal's will.

CARDIAC MUSCLES: The cardiac muscles are found in the wall of the heart and

in the wall of large veins (e.g. pulmonary and superior vena cava) where these veins

enter the heart. These show the characters of both unstriped and striped muscle

fiber. Each fibre is a long and cylindrical has a definite sarcolemma.

STRUCTURE OF SKELETAL MUSCLE:Each organised skeletal muscle in our body is made of a number of muscle bundles or fascicles held together by a common collagenous connective tissue layer called fascia.Each muscle bundle contains a number of muscle fibers and each muscle fibre is lined by the plasma membrane called ET enclosing

he Muscle fibre is a syncitium as the sarcoplasm contains many nuclei.The endoplasmic reticulum, i.e., sarcoplasmic reticulum of the muscle fibres is the store house of calcium ions.A large number of parallelly arranged filaments are present in the sarcoplasm called as.Each myofibril has alternate dark and light bands on it and it is due to the distribution pattern of two important proteins: ACTIN and MYOSIN

The light bands contain actin and is called I-band or isotropic band, whereas the dark band called ‘A’ or anisotropic band contains myosin.Actin filaments are thinner as compared to the myosin filaments, hence are commonly called thin and thick filaments respectively.In the centre of each ‘|’ band is an elastic fiber called ‘Z’ line which bisects it.The thin filaments are firmly attached to the ‘Z’ line and the thick filaments in the ‘A’ band are also held together in the middle of this band by a thin fibrous membrane called ‘M'’ line.The portion of the myofibril between two successive ‘Z’ lines is considered as the functional unit of contraction and is called a Sarcomere

In aresting state, the edges of thin filaments on either side of the thick

filaments partially overlap the free ends of the thick filaments leaving the

central part of the thick filaments, and the central part of thick filament, not

overlapped by thin filaments is called the ‘H’ zone.

FUNCTIONS OF MUSCLE TISSUE

MOVEMENT: Our body's skeleton gives enough rigidity to our body that skeletal muscles can yank and pull on it, resulting in body movements such as walking, chewing, running, lifting, manipulating objects with our hands, and picking our noses.

MAINTENANCE of posture: Without much conscious control, our muscles generate a constant contractile force that allows us to maintain an erect or seated position, or posture.

RESPIRATION: Our muscular system automatically drives movement of air

into and out of our body.HEAT GENERATION: Contraction of muscle tissue generates heat, which is essential for maintenance of temperature homeostasis. For instance, if our core body temperature falls, we shiver to generate more heat.

COMMUNICATION: Muscle tissue allows us to talk, gesture, write, and convey our emotional state by doing such things as smiling or frowning.CONSTRICTION OF ORGANS AND BLOOD VESSELS: Nutrients move

through our digestive tract, urine is passed out of the body, and secretions are

propelled out of glands by contraction of smooth muscle. Constriction or relaxation of blood vessels regulates blood pressure and blood distribution throughout the body.

PUMPING BLOOD: Blood moves through the blood vessels because our heart tirelessly receives blood and delivers it to all body tissues and organs.

LET US KNOW WHAT WE HAVE LEARNT!

PART: A VERY SHORT ANSWER TYPE QUESTIONS

A. MULTIPLE CHOICE QUESTIONS:

Q1 Functional unit of striated muscle is:

(a)band

(b)Z-line

(d) Sarcomere

Q2 Myoglobin occurs in:

(a) skeletal muscle

(b) smooth muscle

(d) Both a and b

Q3 Which of the following is multinucleated?

(a) Nonstriated muscle

(b) Striated muscle

(d) Nervous tissue

Q4 Largest Smooth muscle is present in:

(a) Leg

(b)Thigh

(c)Uterus of pregnant women

(d) Urethra

Q5 Muscles which are immune to fatigue are:

(a) Skeleton muscle

(b) unstriped muscle

(d) jaw muscle

B. FILLIN THE BLANKS:

1. In muscle fiber Ca** is stored in ;

2. Two important protein are and .

3. The ions of ............play an important role in muscle contraction.

C. TRUE/ FALSE:

1. Actin is present in thin filament.

2. H-zone of striated muscle fiber represents both thick and thin filaments.

ANSWER KEY: PART-A

A. MULTIPLE CHOICE QUESTIONS:

1.d Functional unit of Striated muscle is sarcomere.

2.a Skeletal muscle fibers are rich in myoglobin pigment.

3.b Striated muscles are syncitial

4.b Thigh have largest smooth muscle fibre.

5.c Cardiac muscles always work tirelessly

B. FILL IN THE BLANKS:

1. Sarcoplasmic Reticulum

2. Actin, Myosin

3. Calcium

C.TRUE/ FALSE:

1. TRUE

2. FALSE Z zone have thin and thick filaments.

PART: B SHORT ANSWER TYPE QUESTIONS

Q1. Distinguish between cardiac and striated muscles?

Q2. How are thick and thin filaments arranged in a muscle fiber?

Q3. Define role of myoglobin in the muscles.

PART: C LONG ANSWER TYPE QUESTIONS

Q1.Elaborate difference between Striated, Smooth and Cardiac muscle

fibre.

Q2. Briefly discuss role of following in muscles;Actin Myosin

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Dear students, as we have previously studied about Epithelial, Connective and

Muscular tissues, in this assignment we will study about Nervous Tissue its

Types and Functions.

NERVOUS TISSUE:Nervous tissue is ectodermal in origin. It exerts the greatest control

over the body’s responsiveness to changing conditions. Nerve cells are excitable by external and internal stimuli.

COMPOSITION OF NERVOUS TISSUE:

Nervous tissue is formed of four types of cells:Neurons, Nerve cells Neuroglia

Ependymal Cells Neuro-secretory cells.

A. NEURONS:A neuron is a nerve cell with all its branches. It is the structural

and functional unit of nervous system. It is the communication unit of nervous system. It may be elongated over 100 cm. Neurons can detect and receive and conduct the nerve impulses to various parts of the

body.A neuron is formed of two main parts:

Cyton, Nerve processes —Dendrites and Dendrons.

Cyton: It is also called perikaryon or soma or cell body. It is of variable

shape. Its granular cytoplasm is called neuroplasm.

Dendrites and Dendrons: These are one or more small sized tapering processes. Each is highly branched to form the terminal arborization.These are afferent in nature and conduct the impulses towards the

cyton.

MAIN FUNCTIONS OF NEURONS:Neuron is the basic unit of the brain Specialized cell designed to transmit information to other

nerve cells, muscles or gland cells.

It helps transmit nerve signals, or impulses, down a long axon.The main part of neuron is called cell body; it contains all

of the important parts of the cell that allow it to function properly.

B. NEUROGLIA OR GLIA CELLS:These are non-nervous cells which lie between the neurons of the CNS, ganglia and between photoreceptors of retina of eye.These protect and support the neurons and form more than one half the volume of nervous tissue.The Neuroglia cells are of three types:Microglial cells. . Oligodendrocytes

FUNCTIONS:These are capable of division and help in wear and tear of the CNS.These are insulate the adjoining neurons and prevent the lateral transmission of impulses.

These provide nutrition to the neurons.

These acts as phagocytes and eat up the microbes.These help in memory processes.

B.EPENDYMAL CELLS:These are cuboidal and ciliated epithelial cells which line the

cavities of brain and spinal cord. These form an epithelium called ependyma. Their cilia move the CSF.

FUNCTIONS:It plays an important role in the production and regulation of CSF.The apical surfaces are covered in a layer of cilia, which circulates CSF around the CNS.

The apical surfaces also covered with microvilli, which absorbs CSF (Cerebro Spinal Fluid)

C. NEUROSECRETORY CELLS:These are special type of neurons of the hypothalamus of brain. These are endocrine in function and secret neurohormones which are carried

by the blood. Ex. TSH, STH, FSH, etc.

FUNCTIONS:It is also a type of neuron or nerve cell, whose function is to translate

neural signals into chemical stimuli.

(A). Multiple choice questions:

(i). The structural and functional unit of nervous system is....

(a). Cell

(b). Tissue

(c). Neuron

(d). Nephron

(ii). Which cells lie between the neurons of the CNS, ganglia and between photoreceptors of Retina of eye

(a). Neurosecretory cells.

(b). Ependymal cells

(c). Neuroglia cells.

(d). Cyton

(iii). Which cells plays an important role in the production and regulation of CSF.

(a). Ependymal cells

(b). Glia Cells

(c). Neurosecretory cells

(d). Dendron

(iv). Neuron is the basic unit of

(a). Heart

(b). Brain

(c). Kidneys

(d). Lungs

(v). Cyton is also called.

(a). Perikaryon

(b). Nephron

(c). Dendron

(d). None of above

(B). True or False:

(i). Neuron is the structural and unctional unit of nervous system.

(ii). The main function of neurosecretory cells is to translate neural

signals into chemical stimuli.

(C). Fill in the blanks:

(i). cells are special type of neurons of the hypothalamus.

of brain.

(ii). CSF stands for .

(iii). cells are endocrine in function.

ANSWER KEY: PART-A

(A). Multiple choice questions:

(i). (c) Neuron Neuron is the structural and functional unit of nervous

system.

(ii). (c). Neuroglia cells. Cells lie between the neurons of the CNS,

Ganglia and between Photoreceptors of retina of eye.

(iii) (a). Ependymal cells. plays an important role in the production and

regulation of CSF.

(iv) (b). Brain. Neuron is the basic unit of brain, structural and

functional unit of nervous system.

(v) (a).Perikaryon. It is also called perikaryon or soma or cell body.

(B). True or False:

(i). True. Neuron is the structural and functional unit of nervous system.

(ii). True. It translate neural signals into chemical stimuli.

(C). Fill in the blanks:

(i). Neurosecretory cells.

(ii). Cerebro Spinal Fluid

(iii). Neurosecretory

(i). Define the term neuron. Write its types.

(ii). Draw a structure of typical neuron.

(iii). Write main functions of (i). Neurons (ii). Neurosecretory cells.

(iv). Write short note on. Cyton and Dendrites, Dendrons.

(i). Briefly explain types of neurons with its main functions.

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COCKROACHES are the most wide spread of all insects being worldwide in distribution. Cockroaches are brown or black bodied animals that are included in class Insecta of Phylum Arthropoda.

Phylum: Arthropoda

Class: Insecta

Subclass: Pterygota

Order: Dictyoptera

Family: Blattidae

Genus: Periplaneta

Species: americana

MORPHOLOGY Colour: Brownor Black. (Bright yellow, red and green coloured ones

have also been reported in tropical regions)Size: Ranges from % inches to 3 inches (0.6-7.6 cm.

Grossly: They have long antenna, legs and flat extension of the upper body wall that conceals head.Behaviour: Nocturnal omnivores live in damp places throughout the world. They have become residents of human homes and thus is serious pests and vectors of several diseases.

The adults of the common species of cockroach, INE

GE are about 34-53 mm long with the wings that extend beyond the tip of the abdomen in males.The body is segmented and divisible into three distinct regions

HEAD, THORAX and ABDOMEN.The entire body is covered by a hard chitinous exoskeleton (brown in colour). In each segment, exoskeleton has hardened plates called SCLERITES (Tergites dorsally and Sternites ventrally) that are joined to each other by a thin and flexible articular membrane (Arthrodial Membrane).

Triangular in shape and lies anteriorly at right angles to the

longitudinal body axis.Formed by fusion of six segments and shows great mobility in all directions due to flexible neck.

A pair of compound eyes and a pair of thread like antennae which have sensory receptors that help in monitoring the environment.Biting and chewing type of mouth parts.

Mouthparts-

a) Labrum(upper lip),

b) a pair of mandibles,

c) a pair of maxillae,

d) Hypopharynx (acting as tongue).

It consists of three parts: Prothorax, Mesothorax, Metathorax.Connected to the head by short extension of the prothorax

known as the neck.Each thoracic segment bears.a pair of walking legs.First pair of wings ( forewings) arises from mesothorax and second pair(hindwings) from metathorax.

Forewings (called teq miria) are opaque dark and leathery and cover the hind wings when at rest The hind wings are transparent, membranous and are used in

flight.

Females: The 7" sternum is boat shaped and together with 8" and 9 sterna forms a brood or genital pouch whose anterior part contains female gonopore, spermathecal pores and collateral glands.

Males: The genital pouch lies at the hind end of the abdomen bound dorsally by 9t* and 10* terga and ventrally by the 9%

sternum. It contains dorsal anus, ventral male genital pore and gonapophysis.Males bear a pair of short thread like [J which are absent in females.

In both sexes, the 10% segment bears a pair of joined filamentous structures called

COCKROACH is RR. However true coelom occurs only in

embryonic stage. The body cavity of adults is filled with J GR and is called a

The alimentary canal is divided into three regions:The mouth opens into a short tubular EE leading to a narrow tubular passage called IEE which inturn opens into a sac like structure called J used for storing of food.

The crop is followed by gizzard or proventriculus, which has six

highly chitinous plates called teeth. It helps in grinding the food particles.

Atjunction of foregut and midgut, a ring of 6-8 blind tubules called hepatic or gastric caecae is present, which secretes digestive

juice.At junction of midgut and hindgut is present another ring of 100-150 yellow coloured thin filamentous Malpighian tubules, which removes excretory products from hemolymph.

The hindgut is divided into ileum, colon and rectum. The rectum

opens out through anus.

Blood vascular is an open type. Blood vessels are poorly developed and open into haemocoel.

Visceral organs are located in haemccoel and bathed in haemolymph, which is composed of colourless plasma and haemocytes.

Heart consists of elongated muscular tube lying along mid dorsal line of thorax and abdomen. It is differentiated into funnel shaped chambers with ostia on either side. Blood from sinuses enter heart through ostia and is pumped anteriorly to sinuses again.It consists of a network of trachea, that opens through 10 pairs of small holes called spiracles present on the lateral side of the body.Tracheal tubes are divided into tracheoles and carry oxygen from air to all the parts.The opening of the spiracles is regulated by the sphincters.

Cockroach is jificetelic.Excretion is performed by Malpighian tubules. Each tubule is lined by glandular and ciliated cells. They absorb nitrogenous waste products and convert them into uric acid which is excreted out through the hindgut.

It consists of a series of fused, segmentally arranged ganglia joined by paired longitudinal connectives on the ventral side.Three ganglia lie in the thorax, and six in the abdomen.The head holds a bit of a nervous system while the rest is situated along the ventral side of the body.Brain is represented by supra-oesophageal ganglion which supplies nerves to the antennae and eyes.Sense organs- ne

Each eye consists of about 2000 hexagonal ommatidia. With help of several ommatidia, a cockroach receives several images of an object. This kind of vision is known as i with more sensitivity and less resolution.

Cockroaches are dioecious and both sexes have well developed reproductive organs.Male consists of a pair of testes one lying on each lateral side in the 4%"-6t* abdominal segments. From each testis arises a thin vas deferens, which opens into ejaculatory duct through seminal

vesicle. The ejaculatory duct opens into male gonopore situated ventral to anus.

Accessory reproductive organ- Mushroom shaped gland present in the 6%-7" abdominal segments.External genitalia- Male gonapophysis or phallomere.Sperms are stored in the seminal vesicles and are glued together in form of bundles called as spermatophores which are discharged during copulation.

Females consists of two large ovaries, lying laterally in 2"¢ -6"

abdominal segments. Each ovary is formed of a group of eight ovarian tubules or ovarioles, containing a chain of developing ova.Oviducts of each ovary unite into a single median oviduct(also called vagina) which opens into the genital chamber. A pair of spermathecal is present in the 6 segment which opens into the genital chamber.

Sperms are transferred through spermatophores.Their fertilised eggs are encased in capsules called Bjaaaaa

(Dark reddish to blackish brown capsule, about 3/8” (8mm)long), which are dropped or glued to a suitable surface.On an average, females produce 9-10 oothecae, each containing: 14-16 eggs.Development is paurometabolous, meaning there is development through nymphial stage. The nymph looks very much like adults.

The nymph grows by moulting 13 times to reach the adult form.The next to last nymphal stage has wing pads but only adult

cockroaches have wings.

A.) MULTIPLE CHOICE QUESTIONS:

1.) The body of cockroach is divided into how many parts?

a) Two

b) Three

c) One

d) Undivided

2.)Which of the following is not a mouthpart of the cockroach?

a.) Labrum

b.) Hypopharynx

c.) Sclerites

d.) Maxillae

3.) Which of the following segment in female’s abdomen is boat

shapes and takes part in brood formation?

a.) 6

b.) 7

c.) gm

d.) 10%

4.) Hepatic caecae are present at junction of:

a.) Hypopharynx and foregut

b.) Foregut and midgut

c.) Midgut and hindgut

d.) Foregut and hindgut

5.) Ovaries are present in which of the following segments?

a.) 1% -7'

b.)2nd.6"

c.) gth_gth

d.)5t-gtn

B.) FILL UPS:

1.)In both sexes, the 10 segment bears a pair of joined filamentous

structures called

2.). Heart is differentiated into funnel shaped chambers with

on either side.

3.) Brain is represented by which supplies nerves to the

antennae and eyes.

C.) TRUE OR FALSE:

1.) The hindwings are dark, leathery and opaque.

2.) Accessory reproductive organ in males (Mushroom shaped

gland) is present in the 6-7 abdominal segments.

ANSWER KEY: PART (A)

A) MULTIPLE CHOICE QUESTIONS :

1. b) Three parts

2 c)Sclerites

3. b) 7 segment

4 b) Foregut and midgut

5. b) 2nd.6th

B) FILL UPS:

1. Anal cerci

2. Ostia

3. Supra-oesophageal ganglion

C) TRUE/ FALSE:

1. False

2. True

PARTB: SHORT ANSWER TYPE QUESTIONS

1.) Name the mouthparts of the cockroach.

2.) Write a short note on the Gastrointestinal system of the cockroach.

3.) Write salient features of the thorax of cockroach.

PARTC: LONG ANSWER TYPE QUESTIONS

1.) What are the major differences between male and female reproductive

system of a cockroach?

2.) Draw a well labelled diagram of female reproductive system of

cockroach.

A78

RECAPITULATION:Dear students in the chapter “STRUCTURAL ORGANISATION IN ANIMALS.

you have read all the topics in detail. As this chapter deals with the internal

structure of animals, we have learnt that animals have cells as the basic unit,

cells are organized into tissues and in tum the tissues are organized into organsand organs are organized to form organ systems and then into complete organism.

Now let us do NCERT book questions;

Q2. Answer the following.

(i) What is the function of nephridia?

Solution: (i) Nephridia are excretory organs of earthworm, which perform the

function of excretion and osmoregulation. Nephridia regulate the volume and

composition of the body fluids.

Q6. What are the ceilular components of blood?

Solution: Blood is a fluid connective tissue. It is composed of EERE Ge ee Cellular components of blood (blood corpuscles) OR See constitute about 45% of blood volume.Three types of blood cells are:Ree. they are most abundant blood cells.Normal RBC count is 5-5.5 million/mm? in males and 4.5-5 million/mm? in

females) RBCs help in transport of gases and maintain blood pH. The normal WBC count is 5000- 6000/mmé of blood. They are involved in immune response of body and act as soldiers and scavangers Ee. There are about 2,50,000 platelets/mm® of blood. They are involved in blood clotting.

Q7. What are the following and where do you find them in animal body?

(a) Chondrocytes

(b) Axons.

Solution: (a) Chondrocytes — Chondrocytes are the only cells found in cartilage. They are present in spaces called lacunae and they produce andmaintain the matrix of cartilage. Bending ability of cartilage is due to chondrocytes. Cartilage is present at tip of nose, pinna of ear, epiglottis etc.

(b) Axon — Axon is one of the processes of neuron, which is the structural and

functional unit of nervous system. It conducts impulses away from the

cyton. Neurons (nerve cells) are present in brain and spinal cord.

(c) Ciliated epithelium — If the columnar or cuboidal cells bear cilia on their

free surface they are called ciliated epithelium.Their function is to move particles or mucus in a specific direction over the epithelium.They are mainly present in the inner surface of hollow organs like bronchioles and Fallopian tube.

Q 8. Describe various types of epithelial tissues with the help of labelled

diagrams.

Solution: Epithelial tissue is a tissue made of one or more layers of compactly arranged cells that covers external surface and internal free surface of body organs and which is underlined by a basement membrane.The various types of epithelial tissue along with the diagram are given below:

(i) Siviple epithelium ; It is composed of single layer of cells resting on

basement membrane.Simple epithelium generally occurs over secretory and absorptive surfaces.imple epithelium is of several types.

(a) Squamous epithelium: It consists of single layer of flat cells, tightly linked

together and have centrally located oval or spherical nucleus.It is also called pavement epith lium. It is found in walls of "blood vessels, air sacs of lungs, and lining of eye lens.

(b) Cuboidal epithelium: Cells of cuboidal epithelium are as tall as wide, with centrally placed nucleus.Its main functions are secretion and absorption. It lines sweat gland, thyroid follicles, salivary glands.Brush bordered cuboidal epithelium, i.e., cells having microvilli on their free surface lines proximal part of uriniferous tubule,pancreatic duct, testis and ovary.

(c) Columnar epithelium: Cells are with basaily located nucleus.It helps in secretion and absorption.It occurs in lining of intestine, stomach, gall bladder.

(d) Ciliated epithelium: Free surface of columnar and cuboidal cells are

covered with cilia.Cilia help in moving fluids, particles, mucus, etc. in a specific direction.It occurs in the inner surface of Fallopian tubules, nasal passage,bronchioles.

(e) Pseudostratified epithelium: It consists of single layer of cells but some

cells are shorter than others.Due to difference in size of cells, the epithelium appears 2-3 layered.Pseudostratified columnar epithelium occurs in urethra and parotid salivary gland. Pseudostratified columnar ciliated epithelium (only larger

cells ciliated) occurs in lining layer of nasal’ chambers, trachea and large bronchi.

It helps in moving mucus and foreign particles.

(ii) Compound Epithelium / Stratified Epithelium:It is multilayered epithelium where cells of only the lowermost or basal layer are in contact with basement membrane.It provides protection against mechanical and chemical stresses and has

limited role in secretion and absorption.

It covers dry surface of skin, moist surface of buccal cavity, pharynx,etc.

Different types of compound epithelium are:

[he cells of outer layer are flattened

and squamous while the inner layers are cuboidal cells.Itis of two types: Non- kKeratinised lining oesophagus, pharynx, buccal cavity, cornea, vagina and anal canal and keratinised (comified):

forming epidermis of skin, hair, horn and nail.

he outer layer of cuboidal cells and

basal layer of columnar cells. It lines ducts of sweat glands, large salivary and

pancreatic ducts. Both upper and basal layers are made of columnar cells, e.g., epiglottis covering, part of urethra.

Pe. Outer layer consists of ciliated

columnar cells and basal layer of columnar cells, e.g., larynx.This is stratified epithelium which contains cuboidal or columnar shaped cells, which are thin and stretchable.No basement membrane is present.It lines the inner surface of renal calyces, urinary bladder, ureter.

It consists of specialised epithelial cells which synthesise intracellular macromolecules (protein in pancreas, lipids in adrenal glands, glycoprotein in salivary glands and all the three in mammary glands)

Q10. Mark the odd one in each series.

(a) Areolar tissue; blood; neuron; tendon

(b) RBC; WBC; platelets; cartilage

(d) Maxilla; mandible; labrum; antennae

(e) Protonema; mesothorax; metathorax; coxa.

Solution:(a) Neuron: Areolar tissue, blood and tendon are connective tissues while

neuron is a part a nervous tissue.

(b) Cartilage: RBC, WBC and platelets are parts of vascular connective tissue

while cartilage is skeletal connective tissue.

(c) Ligament: Ligament is a connective tissue.

(d) Antennae: Maxilla, mandible and labrum are mouth parts of cockroach

while antennae are sense organs.

(e) Protonema: Protonema is a filamentous juvenile stage in life cycle of

Bryophytes, while mesothorax, metathorax and coxa are appendages of cockroach.

Q14. (b) Mention the function of the MALPIGHIAN TUBULES.

Solution. MALPIGHIAN TUBULES are the excretory organs in Cockroach.

These lie openly in the haemolymph. They extract excretory materials from

the haemolymph and open up at the junction of mid gut and the hind gut in the

food canal. They are around 150 in number.

A79

Dear students, as we have already studied about various tissues found in animals now we will sum up the chapter with important diagrams from the chapter and run through the chapter with the help of a test.

The structure of the cells varies according to their function. Therefore, the

tissues are different and broadly classified into four types:

1. EPITHELIAL TISSUE

2. CONNECTIVE TISSUE

3. MUSCULAR TISSUE

4. NEURAL TISSUE

EPITHELIAL TISSUE An epithelium is a tissue composed of one or more layers of cells covering the external and internal surfaces of various body parts. Epithelial tissue also forms glands.There are two types of epithelial tissues namely:

1. SIMPLE EPITHELIUM

2. COMPOUND EPITHELIUM

These tissues show different types on the basis of cell shape and number of layers they form. For eg. Squamous epithelium, Cuboidal epithelium,Columnar epithelium, Ciliated epithelium, Cuboidal epithelium and Glandular epithelium.

CONNECTIVE TISSUE Connective tissues, as the name implies, support and connect different tissues and organs of the body. Connective tissue is made up of a few

cells present in the intercellular framework of protein fibres secreted by

the cells, known as a es,

TYPES OF CONNECTIVE TISSUE:

1. LOOSE CONNECTIVE TISSUE

2. SPECIALISED CONNECTIVE TISSUE

3. DENSE CONNECTIVE TISSUE

MUSCULAR TISSUE In humans muscles constitute about 40-50 percent of the total body weight.These muscles are broadly classified into three categories:

1. SKELETAL OR STRIPED OR VOLUNTARY MUSCLES

2. SMOOTH OR UNSTRIPED OR INVOLUNTARY MUSCLES

3. CARDIAC MUSCLES

NEURAL TISSUE Nervous tissue is ectodermal in origin. It exerts the greatest control over the body’s responsiveness to changing conditions. Nerve cells are excitable by

external and internal stimuli.Nervous tissue is formed of: Neurons and Nerve cells, Neuroglia

Cockroaches are the most wide spread of all insects being worldwide in distribution. Cockroaches are brown or black bodied animals that are

included in class Insecta of Phylum Arthropoda.

Phylum: Arthropoda

Class: Insecta

Subclass: Pterygota

Order: Dictyoptera

Family: Blattidae

Genus: Periplaneta

Species: americana

Cockroach is coelomate. However true coelom occurs only in embryonic stage. The body cavity of adults is filled with haemolymph

(blood) and is called haemocoel. Internal anatomy shows following vital

organ systems

A.) MULTIPLE CHOICE QUESTIONS:

1. Gap, tight and adhering junctions are found in:

a) Epithelial tissue

b) Connective tissue

c) Muscular tissue

d) Neural tissue

2. Ligaments connect bones together and withstand a lot of stress.

What type of connective tissue should you expect ligaments to contain?

a) Dense irregular connective tissue

b) Areolar tissue

c) Dense regular connective tissue

d) Adipose tissue

3. Muscles which are immune to fatigue are:

a) Skeleton muscle

b) Unstriped muscle

c) Cardiac muscle

d) Jaw muscle

4. The structural and functional unit of nervous system is:

a) Cell

b) Tissue

c) Neuron

d) Nephron

5. The body of cockroach is divided into how many parts?

a) Two

b) Three

c) One

d) Undivided

B)FILL UPS:

1. Areolar tissue is a connective tissue.

2. In comparison to human erythrocytes, frog’s erythrocytes are .

3. Brain is represented by which supplies nerves to the antennae and eyes.

C) TRUE /FALSE:

1. Actin is present in thin filament.

2. Accessory reproductive organ in males (Mushroom shaped gland) is present in the 6-7" abdominal segments.

ANSWER KEY - PARTA

A)MULTIPLE CHOICE QUESTIONS:

1. a) These are junctions which help in joining of adjoining cells.

2. c) Dense regular connective tissue.

3. c) Cardiac muscles work tirelessly.

4. c) Neuron- helps in transmission nerve impulses.

5. b) Cockroach is divided into three parts.

B)FILL UPS:

1. Loose

2. Nucleated with haemoglobin

3. Supra-oesophageal ganglion

C) TRUE OR FALSE:

1. TRUE

2. TRUE

PART B: SHORT ANSWER TYPE QUESTIONS

1. Name the mouthparts of the cockroach.

2. How are thick and thin filaments arranged in a muscle fiber?

3. Write a short note on specialised connective tissue.

PART C: LONG ANSWER TYPE QUESTIONS

1. Draw a well labelled diagram of female reproductive system of cockroach.

2. Elaborate difference between Striated, Smooth and Cardiac muscle fiber.

3. Describe various types of epithelial tissues with the help of labelled

diagrams.

Plus One

Friday, 26 August 2022

7-STRUCTURAL ORGANIZATION IN ANIMALS

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