2. tissues (1)
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Chapter 2. Animal Tissues
Animals are multicellular heterotrophs whose cells lack cell walls. At some point during their
lives, all animals are capable of movement, although not all animals have muscles they use for this. In themost commonly encountered animals, the mobile stage is the adult, although some animals (such as corals
and sponges) have sessile (or nonmobile) adult phases and mobile juvenile forms. Both animal and plant
evolutionary history show the development of multicellularity and the move from water to land (as well
as a secondary adaptation back to water, for example dolphins, whales, duckweed, and elodea).
Animals developed external or internal skeletons to provide support, skin to prevent or lessen
water loss, muscles that allowed them to move in search of food, brains and nervous systems for
integration of stimuli, and internal digestive systems.
Organs in animals are composed of a number of different tissue types. For example, the stomach
has epithelial tissue making linings and secreting gastric juices, connective tissues. Plants are simpler
organisms than animals, having three organ systems and fewer organs than do vertebrate animals. Organs
are composed of tissues, which are in turn composed of cells. Plants have three tissue types: ground,
dermal, and vascular. Animals have four: epithelial, connective, muscle, and bone.
EPITHELIAL TISSUE
Epithelial tissue is made of closely-packed cells arranged in flat sheets. Epithelia form the surface
of the skin and line the various cavities and tubes of the body. The epithelia that form the inner lining of
blood and lymph vessels are called endothelia. The apical surface of epithelial cells is exposed to the
"external environment", the lumen of the organ or the air. The basolateral surface is exposed to the
internal environment (ECF). The entire sheet of epithelial cells is attached to a layer of extracellular
matrix that is called the basement membrane or, better (because it is not a membrane in the biological
sense), the basal lamina. Epithelial tissue covers body surfaces and lines body cavities. Functions include
lining, protecting, and forming glands. Three types of epithelium occur:
Squamous epithelium consists of flattened cells with a centrally located oval or sphericalnucleus. It forms the inner lining of lungs alveoli, heart, blood vessels, lining of eye lens, outer and
inner lining of Bowman’s capsule.
Cuboidal epithelium consists of cube-shaped cells which are as tall as wide with a central
nucleus. They often form microvilli at their free surfaces giving a brush like appearance, hence called brush bordered cuboidal epithelium. They also develop cilia in certain parts of nephrons of kidney
hence called ciliated cuboidal epithelium.
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Fig. 2.1. Types of epithelial tissues on the basis of arrangementof layers.
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Columnar epithelium consists of elongated cells with a basally located nucleus. They also develop
microvilli and cilia like the cuboidal epithelium. In the lining of the epididymis they develop non-
motile stereocilia. They are secretory in nature (glandular) in gastric glands and mucus secreting
(goblet cells) in lining of the gastrointestinal tract.Any epithelium can be simple or stratified. Simple epithelium has only a single cell layer where
every cells on basement membrane. Stratified epithelium has more than one layer of cells and only the
deepest cells rest on the basement membrane. Pseudostratified epithelium is a single layer of cells but
due to difference in the size of the cells they appear at first glance to form two layers.Functions of epithelial cells include:
• Movement of materials in, out or around the body.
•
Protection of the internal environment against the external environment.• Secretion of a product.
Glands can be single epithelial cells, such as the goblet cells that line the intestine. Multicellular
glands include the endocrine glands. Many animals have their skin composed of epithelium. Vertebrates
have keratin in their skin cells to reduce water loss. Many other animals secrete mucus or other materials
from their skin, such as earthworms do.
SIMPLE STRATIFIED PSEUDOSTRATIFIED
1. Squamous (Lining of pleural cavityand Blood vessels)
2. Cuboidal (Bronchioles, Sweatglands)
(i) Brush bordered (PCT)
(ii) Germinal (Testes and Ovary)
(iii)Ciliated (Nephrons)
3. Columnar (Glandular ducts, Gallbladder)
(i) Ciliated (Fallopian tube)
(ii) Stereociliated (Epididymis)
(iii)Sensory (Retina, Tongue, Brain)
1. Stratified Squamous(Buccal cavity, Oesophagus,Cornea, Vagina)
(i) Keratinized (Epidermis
of skin)
(ii) Non-keratinized
(Buccal cavity, Pharynx,Oesophagus)
2. Stratified Cuboidal (Mammary glands)
3. Stratified Columnar (Pharynx, Epiglottis)
1. Ciliated (Trachea,Bronchi, Bronchioles)
2. Pseudostratified withstereocilia (Epididymis,
Urethra)
Table. 2.1. Classification of epithelial tissues.
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Fig. 2.2. (a) Photograph of peripheral portion of the chick blastodisc atabout 33 hours of incubation. Even though there are several layers of cellsvisible, they are all distinct and separate simple squamous epitheliumlayers. (b) CS through small intestine. The tall, vertical cells seen at the topof the tissue are columnar cells (red arrow)- simple columnar epithelium
(the cells at the bottom are connective tissue).
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CONNECTIVE TISSUE
The cells of connective tissue are embedded in a great amount of extracellular material. This matrix is
secreted by the cells. It consists of protein fibers embedded in an amorphous mixture of protein- polysaccharide (proteoglycan) molecules. Fibres in connective tissue can be divided into three types:
collagen fibres,
reticular fibres and
elastic fibres.
1. Collagen fibres are
the dominant fibre
type in most
connective tissues.
The primary function
of collagen fibres is
to add strength to the
connective tissue.2. Reticular fibres are
very delicate and
form fine networksinstead of thick
bundles. They are
usually not visible in
histological sections
but can be
demonstrated by
using special stains.
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Fig. 2.3. Types of fibres in the connective tissues.
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For example, in silver stained sections reticular fibres look like fine, black threads - coarse collagen fibres
appear reddish brown in the same type of preparation.
3. Elastic fibres are coloured in fresh tissues - they are light yellow - but this colouration is only visible if
large amounts of elastic fibres are present in the tissue, for example, in the elastic ligaments of the
vertebral column.Connective
cells are separatedfrom one another by
a non-cellular
matrix. The matrix
may be solid (as in
bone), soft (as in
loose connective
tissue), or liquid (as
in blood). Two
types of connective
tissue are Loose
Connective Tissue
(LCT) and DenseConnective Tissue
(DCT). These two
tissues are
distinguishedaccording to the
relative amounts of
fibres they contain. Dense connective tissues are completely dominated by fibres. They are subdivided
according to the spatial arrangement of the fibres in the tissue.
In dense irregular connective tissue the fibres do not show a clear orientation within the tissue but
instead form a densely woven three-dimensional network. A good example is the dermis of the skin. We
talk about regular dense connective tissue if the fibres run parallel to each other. Good examples of
regular dense connective tissue are tendons, ligaments and the fasciae and aponeuroses of muscles. Loose connective tissue is relatively cell rich, soft and compliant. It is also rich in vessels and
nerves. It is best understood as a kind of generalised connective tissue in which all connective tissue cell
types may occur. Loose connective tissue may occur in some special variants: mucous connective tissue,
reticular connective tissue and adipose tissue. LCT occurs beneath epithelium in skin and many internal
organs, such as lungs, arteries and the urinary bladder. This tissue type also forms a protective layer over
muscle, nerves, and blood vessels.
Connective tissue cells are usually divided into two groups based on their ability to move within
the connective tissue. Fibrocytes (or fibroblasts) and fat cells are fixed cells. Macrophages, monocytes,
lymphocytes, plasma cells, eosinophils and mast cells are wandering cells.
1. Fibrocytes. Fibrocytes are the most common cell type in connective tissues. They are the "true"
connective tissue cells. The cytoplasm of a resting (i.e. inactive) fibrocyte does not contain many
organelles. This situation changes if the fibrocytes are stimulated, for example, by damage to the
surrounding tissue. In this case the fibrocyte is transformed into a fibroblast, which contains large
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Fig. 2.4. Types of dense connective tissues.
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amounts of the
organelles which
are necessary for
the synthesis and
excretion of proteins needed to
repair the tissuedamage. Fibrocytes
do not usually leave
the connective
tissue. They are,
however, able to
perform amoeboid
movement.
2. Reticular cells.Reticular cells are
usually larger than
an averagefibrocyte. They are
the "fibrocytes" of
reticular connective tissue and form a network of reticular fibres, for example, in the lymphoid organs.
Their nuclei are typically large and lightly stained and the cytoplasm may be visible amongst the cells
which are housed within the network of reticular fibres.
3. Adipocytes. Fat cells or adipocytes are fixed cells in loose connective tissue. Their main function is
the storage of lipids. If "well fed" the cytoplasm only forms a very narrow rim around a large central lipid
droplet. The flattened nucleus may be found in a slightly thickened part of this cytoplasmic rim - if it is
present in the section, which may not be the case since the diameter of an adipocyte (up to 100 µm) is
considerable larger than the thickness of typical histological sections. A "starving" adipocyte may contain
multiple small lipid droplets and gradually comes to resemble a fibrocyte.
4. Mast cells.Mast cells are -
like macrophages,
lymphocytes and
eosinophils - in
demand when
something goes
wrong in the
connective tissue.
Quite a few of
them are present inhealthy connective
tissue as they stand
on guard and
monitor the localsituation. The
cytoplasm of mast
cells is filled by
numerous largevesicles. Mast
cells discharge the
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Fig. 2.5. Types of adipose connective tissues.
Fig. 2.6. Wandering cells of the connective tissues.
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contents of these vesicles if they come in contact with antigens, for example, proteins on the surface of an
invading bacterium or, in allergic reactions, in response to antigens found, for example, on the surface of
pollen grains.
MUSCLE TISSUE
Muscle tissue facilitates movement of the animal by contraction of individual muscle cells
(referred to as muscle fibers). Three types of muscle fibers occur in animals are skeletal (striated), smoothand cardiac.
Muscle fibers are multinucleated, with the nuclei located just under the plasma membrane. Most
of the cell is occupied by striated, thread-like myofibrils. Within each myofibril there are dense Z lines. A
sarcomere (or muscle functional unit) extends from Z line to Z line. Each sarcomere has thick and thinfilaments. The thick filaments are made of myosin and occupy the center of each sarcomere. Thin
filaments are made of actin and anchor to the Z line.
1. Skeletal Muscles.These muscles are generally attached to bones and are at work every time, as they are responsible
for moving parts of the body, such as the limbs, trunk, and face, i.e. they are concerned with voluntary
movements of the body. A skeletal muscle is made up of elongated cells called muscle fibres. Contractionof these fibres tend the muscle to move as a whole. Skeletal muscle fibres are grouped into dense bundles
called as fascicles. A group of fascicles bound together by connective tissue to form a functional muscle.
When viewed under a microscope, skeletal muscles appear to have striations (bands or stripes).
This gives skeleton muscle the name of striated muscles. Mostly these muscles are under the control of
the central nervous system (CNS).
Since these are long and slender
in appearance, they are often
called as muscle fibres rather than
muscle cells. Muscle fibres
together with the connective
tissue, blood vessels, and nerves
form a skeletal muscle.
2. Smooth Muscles.These are spindle shaped,
uni-nucleate, non-striated and
intertwined to form a sheet of
smooth muscle tissue. These are
usually not under the voluntary
control and are found in the
internal organs such as stomach,
intestine, walls of blood vessels,
etc. Smooth muscle fibers are
surrounded by connective tissue,
but the connective tissue does notunite to form tendons as it does in
skeletal muscles. Most smooth
muscle cells can contract without
stimulation from the nervous
system. Because most of its
movements cannot be consciously
controlled, smooth muscles are
also referred to as involuntary
muscles.
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Fig. 2.7. Summary of major types of tissues with their locationin the human body.
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3. Cardiac Muscles.These are striated muscles but not under voluntary control. Cardiac muscles are found only inside
the heart and contract without direct stimulation from the nervous system. A bundle of specialized muscle
cells in the upper part of the heart sends electrical signals through cardiac muscle tissue, causing the heartto rhythmically contract and pump blood through the body. The cardiac muscle cell contains one nucleus
which is located near the center so that adjacent cells form branching fibers pass the nerve impulses from
cell to cell.
NERVOUS TISSUE
Nervous tissue functions in the integration of stimulus and control of response to that stimulus.
Nerve cells are called neurons. Each neuron has a cell body, an axon and many dendrites. The axons of
most neurons are covered with a lipid layer known as the myelin sheath. The myelin sheath both
Insulates and speeds up transmission of action potentials through the axon. In the peripheral nervous
system, myelin is produced by Schwann cells, which surround the axon. Gaps (nodes) in the myelin
sheath along the length of the axon are known as the nodes of Ranvier. Neurons transmit nerve
messages. Glial cells are in direct contact with neurons and often surround them.
• Cell body – It is the largest part, contains the nucleus and much of the cytoplasm (area between the
nucleus and the cell membrane). It is responsible for most of the metabolic activity of the cell,
including the generation of ATP and synthesis of protein.
• Dendrites – These are short branch extensions spreading out from the cell body. Dendrites receive
stimulus (action potentials) and carry impulses from the environment or from other neurons and carry
them towards the cell body.
• Axon – It is a long fiber that carries impulses away from the cell body. Each neuron has only one
axon. The axon ends in a series of small swellings called axon terminals.
The neuron is the functional unit of the nervous system. Humans have about 100 billion neurons
in their brain alone! While variable in size and shape, all neurons have three parts. Dendrites receive
information from another cell and transmit the message to the cell body. The cell body contains the
nucleus, mitochondria and other organelles typical of eukaryotic cells. The axon conducts messages awayfrom the cell body.
SKIN
Skin is an organ of the integumentary system made up of multiple layers of epithelial tissues that
guard underlying muscles and organs. As the interface with the surroundings, it plays the most important
role in protecting against pathogens. Its other main functions are insulation and temperature regulation,
sensation and vitamin D and B synthesis. Skin is considered one of the most important parts of the body.
Skin has pigmentation, or melanin, provided by melanocytes, which absorb some of the
potentially dangerous ultraviolet radiation in sunlight. It also contains DNA repair enzymes which help to
reverse UV damage, and people who lack the genes for these enzymes suffer high rates of skin cancer.
One form predominantly produced by UV light, malignant melanoma, is particularly invasive, causing itto spread quickly, and can often be deadly.
Mammalian skin often contains hairs, which in sufficient density is called fur. The hair mainly
serves to augment the insulation the skin provides, but can also serve as a secondary sexual characteristic
or as camouflage.
The skin is often known as the largest organ of the human body. This applies to exterior surface,
as it covers the body, appearing to have the largest surface area of all the organs. Moreover, it applies to
weight, as it weighs more than any single internal organ, accounting for about 15 percent of body weight.
For the average adult human, the skin has a surface area of between 1.5-2.0 square meters, most of it is
between 2-3 mm thick. The average square inch of skin holds 650 sweat glands, 20 blood vessels, 60,000
melanocytes, and more than a thousand nerve endings.
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Skin is composed of three primary layers: the epidermis, which provides waterproofing and
serves as a barrier to infection; the dermis, which serves as a location for the appendages of skin; and the
hypodermis (subcutaneous adipose layer), which is called the basement membrane.
Epidermis.Epidermis is the outermost
layer of the skin. It forms the
waterproof, protective wrap over the
body's surface and is made up of
stratified squamous epithelium with
an underlying basal lamina. The
outermost epidermis consists of
stratified squamous epithelium with
an underlying connective tissue
section, or dermis, and a hypodermis,
or basement membrane. It contains no
blood vessels, and is nourished by
diffusion from the dermis. The main
type of cells which make up theepidermis are keratinocytes,
melanocytes, Langerhans cells and
Merkels cells. Epidermis is divided
into several layers where cells are
formed through mitosis at the
innermost layers. They move up the
strata changing shape and composition
as they differentiate and become filled
with keratin. They eventually reach
the top layer called stratum corneum
and become sloughed off, or desquamated. This process is called keratinization and takes place within
weeks. This keratinized layer of skin is responsible for keeping water in the body and keeping other harmful chemicals and pathogens out, making skin a natural barrier to infection. The outermost layer of
epidermis consists of 25 to 30 layers of dead cells. Epidermis is divided into the following 5 sublayers or
strata:
Stratum corneum
Stratum lucidum
Stratum granulosum
Stratum spinosum
Stratum germinativum (also called
"stratum basale")
Dermis.The dermis is the layer of skin beneath the
epidermis that consists of connective tissue and
cushions the body from stress and strain. The
dermis is tightly connected to the epidermis by a basement membrane. It also harbors many nerve
endings that provide the sense of touch and heat. It
contains the hair follicles, sweat glands, sebaceous
glands, apocrine glands and blood vessels. The
blood vessels in the dermis provide nourishment
and waste removal to its own cells as well as the
Stratum basale of the epidermis. The dermis is structurally divided into two areas: a superficial area
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Fig. 2.8. Section of skin showing the position of layers andglands.
Fig. 2.9. Enlarged view of epidermis showingthe location of melanocytes.
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adjacent to the epidermis, called the papillary region, and a deep thicker area known as the reticular
region.
(a) Papillary region. The papillary region is composed of loose areolar connective tissue. It is named
for its fingerlike projections called papillae, which extend toward the epidermis. Dermal papillae containcapillaries, bare nerve endings, Meissner corpuscles and Merkel discs. The papillae provide the dermis
with a “bumpy” surface that interdigitates with the epidermis, strengthening the connection between the
two layers of skin. In the palms, fingers, soles, and toes, the influence of the papillae projecting into the
epidermis forms contours in the skin's surface. These are called friction ridges, because they help the hand
or foot to grasp by increasing friction. Friction ridges occur in patterns (see fingerprint) that are
genetically determined and are therefore unique to the individual, making it possible to use fingerprints or
footprints as a means of identification.
(b) Reticular region. The reticular region lies deep in the papillary region and is usually much thicker.
It is composed of dense irregular connective tissue, and receives its name from the dense concentration of
collagenous, elastic, and reticular fibers that weave throughout it. These protein fibers give the dermis its
properties of strength, extensibility, and elasticity. Located within the reticular region are also the roots of
the hair, sebaceous glands, sweat glands, receptors, nails, and blood vessels. Tattoo ink is injected into the
dermis. Stretch marks from pregnancy are also located in the dermis.The hypodermis is not part of the skin, and lies below the dermis. Its purpose is to attach the skin
to underlying bone and issue and elastin as well as supplying it with blood vessels and nerves. It consists
of loose connective tissue and elastin.. The main cell types are fibroblasts, macrophages and adipocytes
(the hypodermis contains 50% of body fat). Fat serves as padding and insulation for the body.
Microorganisms like Staphylococcus epidermidis colonize the skin surface. These microorganisms
serve as ecoorgan. The density of skin flora depends on region of the skin. The disinfected skin surface
gets recolonized from bacteria residing in the deeper areas of the hair follicle, gut and urogenital
openings.
Functions of Skin.
1. Protection: Skin is an anatomical barrier between the internal and external environment in bodily
defense; Langerhans cells in the skin are part of the adaptive immune system2. Sensation: Skin contains a variety of nerve endings that react to heat, cold, touch, pressure,
vibration, and tissue injury; see somatosensory system and touch.
3. Heat regulation: The skin contains a blood supply far greater than its requirements which allows
precise control of energy loss by radiation, convection and conduction. Dilated blood vessels increase
perfusion and heat loss while constricted vessels greatly reduce cutaneous blood flow and conserve
heat. Erector pili muscles are significant in animals.
4. Control of evaporation: The skin provides a relatively dry and impermeable barrier to fluid loss.
Loss of this function contributes to the massive fluid loss in burns.
5. Aesthetics and communication: Others see our skin and can assess our mood, physical state and
attractiveness.
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Skin Glands
Sudoriferous glands: Secrete sweat.Sebaceous glands: Secrete oily material, the sebum which keeps the hair and skin smooth, soft,supple and water-proof.Mammary gland: Modified apocrine sweat glands, functional in females only and secrete milk.Meibomian glands: Also called tarsal glands. These add a film of oil over the cornea.Zeis glands: Pours oily substance in the follicles of eyelashes.Ceruminous glands: Secrete ear-wax or cerumen into the ear canal.Perineal glands: Also called as scent glands. They are present around the genital organs andsecrete pheromones.
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6. Storage and synthesis: Skin acts as a storage centre for lipids and water, as well as a means of
synthesis of vitamin D and B by action of UV on certain parts of the skin. This synthesis is linked to
pigmentation, with darker skin producing more vitamin B than D, and vice versa.
7. Excretion: The concentration of urea is 1/130th that of urine. Excretion by sweating is at most a
secondary function to temperature regulation.
8. Absorption: Oxygen, nitrogen and carbon dioxide can diffuse into the epidermis in small
amounts, some animals using their skin for their sole respiration organ. In addition, medicine can be
administered through the skin, by ointments or by means of adhesive patch, such as the nicotine patchor iontophoresis. The skin is an important site of transport in many other organisms.
COMPETITION DESK # 02
1. The gland cells and nerve plexus lie
(a) in between outer and inner epithelial
layer
(b) in the outer epithelial layers(c) in the inner epithelial layers
(d) amidst ectodermal cells
2. Human skin has a keratinized and water-
impermeable layer of flattened cells. This is
called stratum(a) lucidum (b) corneum
(c) malpighi (d) granulosum
3. The epidermis of mammals is characterized
by the absence of
(a) mucous glands (b) femoral glands(c) poison glands (d) all of these
4. Basic unit of muscle contraction is
(a) actin (b) myosin
(c) sarcomere (d) tropomyosin
5. The base of the placoid scale is attached to
stratum compactum by
(a) subcutaneous fibres
(b) laxum fibres
(c) Sharpey’s fibres
(d) fibres of stratum Malpighi
6. Cells of peritoneum comprise
(a) ciliated epithelium
(b) columnar epithelium
(c) glandular epithelium
(d) squamous epithelium
7. Endothelium lining a blood vessel is formed
of
(a) ciliated epithelium
(b) columnar epithelium
(c) cuboidal epithelium
(d) simple squamous epithelium
8. When a person is exposed to coldsurrounding which of the following does not
occur?
(a) Secretion of adrenal medulla and thyroid
increase
(b) Shivering occurs
(c) Vasoconstriction in skin vessels
supplying blood to hairs
(d) Heart beat and volume of blood per
stroke increases
9. The term blubber refers to
(a) a substitute for natural rubber (b) a subcutaneous deposition of fat in
whale
(c) none of these
(d) the irregular heart beat sounds
10. Tendons and ligaments belong to
(a) muscular tissue
(b) epithelial tissue
(c) fibrous connective tissue
(d) areolar connective tissue
11. Mast cells secrete(a) serotonin (b) heparin
(c) histamine (d) all of these
12. A tissue in which matrix is the source of
structural and functional performance is
(a) muscular (b) epithelial
(c) connective (d) nervous
13. Which of the following are dermal in origin?
(a) sebaceous glands
(b) mammary glands
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(c) Piscean glands
(d) none of these
14. Which of the following muscles are
responsible for moving and shaking of theskin?
(a) arrector pili(b) collagen fibres
(c) Paniculus carnosus
(d) sphincter muscles
15. The surface of skin that is heavily used
becomes thicker and tougher and is full of
(a) eledin (b) keratohyalin
(c) keratin (d) albumin
16. Derivative of sweat gland is
(a) Moll’s gland (b) scent glands
(c) sebaceous glands(d) mammary glands
17. Proprio receptors respond to
(a) mechanical stimuli
(b) chemical stimuli(c) odour
(d) none of the above
18. Which of the following layer is the
outermost one of the skin with dead cells?
(a) Stratum lucidum
(b) Stratum corneum
(c) Stratum spinosum(d) Stratum granulosum
19. Stratum corneum is
(a) dead mid-dermal layer
(b) dead and innermost dermal layer
(c) dead outermost epidermal layer (d) outermost dermal layer
20. Stratum lucidum accumulates a shining
substance called(a) luciferin (b) cardiolipin
(c) cerumen (d) eleiden
21. In mammals melanocytes give protection
from (CBSE 2002)
(a) UV rays (b) Infrared rays
(c) X-rays (d) visible light
22. One of the following is scent gland of
mammals (CBSE 2000)
(a) Bartholin (b) anal
(c) prostate (d) adrenal
23. Pacinian corpuscles occur in the skin of
certain parts of body in mammals. These are
(AIIMS 1998)
(a) type of glands
(b) pain receptors(c) naked tactile receptors
(d) encapsulated pressure receptors
24. Sweat glands, in human skin, are located in
the (AIIMS 1996)
(a) dermis of skin
(b) glandular layer of epidermis
(c) malpighian layer of epidermis
(d) subdermal layer of fat cells.
25. The horns of Rhinoceros are composed of
(AIIMS 1996)
(a) bone (b) cartilage
(c) chitin (d) keratin
26. Camouflage of Chameleon is associated
with (AIIMS 1995)
(a) chromosome (b) chromomere(c) chromoplast (d) chromatopore
27. Which of the following layer of epidermis in
man provides the main protection of body
against water loss and the entry of disease
causing organisms? (AIIMS 1994)
(a) Stratum spongiosum
(b) Stratum corneum(c) Stratum lucidium
(d) Stratum germinativum
28. The colour of the skin is due to (AFMC
2001)
(a) neutrophils (b) mesophils(c) melanocytes (d) basophils
29. The receptors for touch superficially present
in the skin are called (BHU 1997)
(a) Pacinian corpuscles
(b) Krause’s end bulbs(c) Meissner’s corpuscles
(d) Stratum lucidium.
30. The deeper layer of the skin of vertebrates is
called (BHU 1996)
(a) dermis (b) cutaneous tissue
(c) epidermis (d) none of these.
31. Stratum lucidum is found in (BHU 1995)
(a) dermis and they release keratin
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(b) epidermis and situated below the
stratum corneum
(c) dermis and secrete keratin
(d) epidermis and originates from hair
follicle.
32. Epidermis is specialized for (CPMT 1998)(a) respiration (b) absorption
(c) protection (d) all of these
33. One of the following is an example of
cutaneous glands (CPMT 1998)
(a) Gastric (b) Pancreas
(c) Sebaceous (d) Salivary
34. Exposed surface of the human body is
covered by the tissue (CPMT 1998)
(a) glandular epithelium
(b) keratinized stratified squamousepithelium
(c) ciliated epithelium
(d) dermis
35. Inner lining of gut, stomach and liver is
made up of (CPMT 1997)
(a) simple squamous epithelium
(b) simple columnar epithelium
(c) simple cuboidal epithelium
(d) all of these
36. Which of these is not an animal tissue?(a) connective (b) xylem
(c) epithelial (d) nervous
37. Tissues are made up of
(a) groups of cells that perform a different
set of functions
(b) collections of cells that perform similar
or related functions
(c) subcellular structures that aid in the
performance of the cell’s role
(d) none of these
38. Which of these is not a function of epithelial
tissue?
(a) covering surfaces
(b) secretion
(c) support of the body(d) lining internal exchange areas
39. Layered epithelial tissue is referred to as
which of these?
(a) squamous (b) stratified
(c) voluntary (d) pseudostratified
40. Which of these cell types covers the inside
of the mouth?
(a) squamous epithelium(b) cartilage(c) blood (d) cuboidal epithelium
41. Protection of the body from infectious
organisms is accomplished by which of
these tissues?
(a) bone (b) muscle
(c) nerve (d) blood
42. Linking of bone to bone in a skeletal system
is accomplished by which of these tissues?
(a) epithelial (b) connective
(c) muscle (d) nervous
43. Cells that line the tubules in the kidneymake up which of these tissues?
(a) adipose
(b) squamous epithelium
(c) cuboidal epithelium(d) stratified epithelium
44. The storage of fat is accomplished by which
of these cell types?
(a) adipose
(b) squamous epithelium
(c) cuboidal epithelium
(d) stratified epithelium
45. Glands are composed of which of these
tissue types?
(a) epithelium (b) connective
(c) muscle (d) nervous
46. Hard parts of the body would be made of
which of these cell/tissue types?
(a) blood (b) bone
(c) muscle (d) nerves
47. Bone acts as a reservoir for which of theseelements?
(a) carbon (b) nitrogen
(c) calcium (d) hydrogen
48. The blood cells that transport oxygen within
the body are
(a) macrophages (b) erythrocytes
(c) platelets (d) leukocytes
49. Contraction of your heart is accomplished
by which of these cell types?
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(a) cardiac (b) skeletal
(c) smooth (d) both a and b
50. Contractions of the uterus during birth are
accomplished by which of these cell types?
(a) cardiac (b) skeletal
(c) smooth (d) both b and c
ANSWERS # 02
1. a 2. b 3. d 4. c 5. c 6. d 7. d 8. d 9. b 10.c11. d 12. c 13. c 14. c 15. c 16. d 17. a 18. b 19. c 20. d21. a 22. b 23. d 24. a 25. d 26. d 27. b 28. c 29. c 30. a31. b 32. d 33. c 34. b 35. b 36. b 37. b 38. c 39. d 40. a41. d 42. b 43. c 44. a 45. a 46. b 47. c 48. b 49. a 50. c
EXPLANATION # 02
2. (b) The outermost cells of stratum lucidum forms a thick layer of hard scale-like, fully keratinized,
flattened cells called stratum corneum. It contains hard keratin filaments (horny cells) which prevents
the passage of water and solutes. In places of friction this layer becomes very thick.
9. (b) In whales and seals the fat of skin forms a thick layer called blubber which is not only reserve food
but also maintains the body temperature.
20. (d) In stratum lucidum, keratohyaline granules are dissolved and transformed into eleiden whichmakes cells semitransparent, shiny and waterproof. It is found in places of friction, such as soles and
palms.
23. (d) Pacinian corpuscles are located in deep layers of dermis of skin, joints, tendons and muscles. Theyrespond to strong pressure and also to vibrations.
29. (c) Meissner’s corpuscles are located in the papillary layer of the dermis just below the epidermis, e.g.
finger tip, lips and nipples. They respond to touch.
33. (c) Sebaceous glands are associated with hair follicles. These secrete oil or sebum which keeps the
hair and skin smooth, soft, supple and water-proof. Emotional stress may increase the secretion of
sebum.
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