Lesson 2

Protection, Support, and

Movement

INTEGUMENTARY,
MUSCULOSKELETAL
SYSTEM
Protection: Integumentary System

Integument - is the external

covering of an animal. It protects
the animal from mechanical and
chemical injury and invasion by
microorganism.
THE INTEGUMENTARY SYSTEM
OF INVERTEBRATES
➢ Single-celled protozoa
- Plasma membrane
➢ Paramecium
- Pellicle (a thick protein coat)
➢ Multicellular invertebrates
- Epidermis (the outer layer)
➢ Some invertebrates
- Cuticles (thin and elastic/,thick and rigid)
➢ Cnidarian (corals)
- Mucus glands
➢ Parasitic flukes and tapeworms
- Tegument
➢ Nematodes and annelids
- Epidermis
➢ Echinoderms
- thin, ciliated epidermis
➢ Arthropods
- exoskeleton
Integument of crustacean
Integument of vertebrates
THE INTEGUMENTARY SYSTEM
OF VERTEBRATES
 Skin - is the vertebrate integument
- largest organ
Skin has 2 main layers:
➢ Dermis
– is the connective tissue meshwork of
collagenous, reticular, and elastic fibers
beneath the epidermis.
➢ Hypodermis
– consisting tissue, adipose tissue, and nerve
endings, separates the skin from deeper tissue.
The Skin of Cartilaginous Fishes
 Multilayered and contains mucous and
sensory cells.
 The dermis contains bone in the form of
small placoid scales called denticles
 Cartilaginous fishes grow throughout life,
the skin area also increases.
 New denticles are produced to maintain
enough of these protective structures at
the skin surface.
 The Skin of Bony Fishes
 Contains scales compose of dermal bone.
 Scales are not shed, they grow at the margins and
over the lower surface.
 Permeable and function in gas exchange.
 The dermis is richly supplied with capillary beds to
facilitate its use in respiration.
 The Epidermis also contains many mucous glands.
 Mucus production helps prevent bacterial and
fungal infections and its reduces friction as fish
swims.
 The Skin of Amphibians
 Consists of stratified epidermis and a
dermis containing mucous and serous
gland plus pigmentation cells.
 Amphibians are transitional between
aquatic and terrestial vertebrates.
 Three problems associated with terrestial
environments are : desiccation, the
damaging effects of ultraviolet light, and
physical abrasion.
 During amphibian evolution, keratin production
increased in the outer layer of the skin cells.
 Keratin is a tough, impermeable protein that
protects the skin in the physically abrasive
rigorous terrestial environment.
 The mucus that mucous glands produce helps
prevent desiccation, facilitates gas exchange when
the skin is used as respiratory organ, and makes
the body slimy which facilitates escape from
predators.
 Within the dermis of some amphibians are poison
glands that produce an unpleasant-tasting or toxic
fluid that acts as a predator deterrent.
 The Skin of Reptiles
 Reflects their greater commitment to a terrestrial
existence.
 The outer layer of epidermis (stratum corneum)
is thick, lacks glands, and is modified into
keratinized scales, scutes (thick scales)
 The thick, keratinized layer resists abrasion,
inhibits dehydration, and protects like a suit of
armor.
 During shedding or molting of the skin of many
reptiles, the outer layer separates from newly
formed epidermis.
 Diffusion of fluid between the layers aids this
separation.
 The Skin of Birds
 Shows typically reptilian features with no
epidermal glands.
 The epidermis is usually thin and only two
or three cell layers thick.
 The most prominent part of the epidermis
are the feathers.
 Air spaces that are part of avian
respiratory system extend into the
dermis.
 Feather position is important in thermal
regulation, flying, and behavior.
The Skin of Mammals
The notable features of mammalian skin are:
➢Hair
➢Epidermal glands
➢Cornified epidermis
➢Dermis
Keratinized cells make up the outer layer,
called the stratum corneum.
 The thickest potion of mammalian skin
is composed of dermis which contains:
➢ Blood vessels
➢ Lymphatic vessels
➢ Nerve endings
➢ Hair follicles
➢ Small muscles
➢ glands
In humans
 The skin regulates body temperature by
opening and closing sweat pores and
perspiring or sweating.
 The skin screens out excessive harmful
ultraviolet rays from the sun
 The skin also an important sense organ,
containing sensory receptors for heat, cold,
touch, pressure, and pain.
 The skin of humans and other mammals
contains several types of glands.
 Sudoriferous glands
- are distributed over most of the human
body surface.
- secrete sweat by a process called
perspiration.
➢ Perspiration - helps to regulate body
temperature and maintain homeostasis.

In some animals, certain sweat glands also

produce pheromones.
➢ Pheromones - chemical that animal
secretes and that communicate with
other members the same species to elicit
certain behavioral responses.
 Sebaceous (oil) glands
- are simple glands connected to hair
follicles in the dermis.
- they lubricate and protect by
secreting sebum.
➢Sebum – is a permeability barrier, an
emollient and protective agent against
microorganisms
- can also act as a pheromone.
 Mammalian skin color is either to pigment
or to anatomical structures that absorbs of
reflect the light.
 Some skin color is due to color of the
blood in superficial blood vessels reflected
through the epidermis.
 Other skin colors may camouflage the
animal.
 In addition, color serve in social
communication, helping members of the
same species to identify each other, their
sex, reproductive status, or social rank.
 Hair – is composed of keratin-filled cells
that develop from the epidermis.
➢ An arrector pili muscle attaches to the
connective tissue sheath of the a hair
follicle surrounding the bulb of the hair
root.
 Nail – like hair, are modifications of the
epidermis.
- are flat, horny plates on the dorsal
surface of the distal segments of the digits.
➢ Horns
➢ Baleen plates
 MOVEMENT AND SUPPORT:
SKELETAL SYSTEM
Four cells types contribute movement:
1. Amoeboid cells
2. Flagellated cells
3. Ciliate cells
4. Muscles cells
With respect to support, organism have three
kinds of skeletons:
1. Fluid hydrostatic skeletons
2. Rigid exoskeletons
3. Rigid endoskeletons
Hydrostatic Skeletons
- is a core liquid surrounded by a
tension resistant sheath of longitudinal
and/or circular muscles.
 Contracting muscle push against a
hydrostatic skeleton, and the transmitted
force generates body movement.
 The hydrostatic skeleton of invertebrates
is an excellent example of adaptation of
major body functions to this simple but
efficient principle of hydrodinamics – use of
the internal pressure of body fluids.
Exoskeletons
- also have locomotion functions because
they provide sites for muscle attachment and
counterforces for muscle movements.
- also support and protect the body,
In arthropods, the epidermis of the body wall
secretes a thick, hard cuticle that water proofs
the body. The cuticle also protects and support
the animal’s soft internal organ.
In crustaceans, the exoskeleton contains
calcium carbonate crystals that make it hard and
inflexible – except at the joints.
Exoskeleton limit an animals growth.
Endoskeletons
 The endoskeletons of sponges consist of
mineral spicules and fibers of spongin that
keep the body from collapsing. Since adult
sponges attach to the substrate, they have
no need for muscle attached to the
endoskeleton.
 The endoskeletons of echinoderms consist
of small, calcareous plates called ossicles.
 Mineralized Tissues and
Invertebrates
 Cartilage – is the supportive tissue that
makes up the major skeletal component
of some gastropods, invertebrate
chordates (amphioxus), jawless fishes such
as hagfishes and lampreys, and sharks and
rays.
- is lighter than bone, it gives these
predatory fishes the speed and agility to
catch prey. It also provides buoyancy
without the need for a swim bladder.
 The Skeletal System of Vertebrates
This endoskeleton consist of two main types
of supportive tissue: cartilage and bone.
 Cartilage – provides site for muscle
attachment, aids in movement at joints,
provides support, and transmits the force of
muscular contraction from one part to the
body to another during movement,
- it consist of cells, fibers, and cellular
matrix.
Bone or Osseous Tissue
- that provides a point of attachment for
muscles and transmits the force of muscular
contraction from one part of the body to another
during movement.
 Bone tissue is more rigid than the other
connective tissues because its homogeneous,
organic ground substance also contains in
organic salts.
 Bone cells are in minute chambers called
lacunae which are arranged in concentric rings
around osteonic canals (formerly called
Haversian systems).
The Skeleton of Fishes
 Both cartilaginous and bony endoskeletons
first appeared in the vertebrates.
 Water has a buoyant effect on the fish body,
the requirement for skeletal support is not
as demanding in these vertebrates as it is in
terrestrial vertebrates.
 Most jawed fishes have an axial skeleton that
includes a notochord, ribs, and cartilaginous
or bony vertebrae.
 Muscle used in locomotion attach to the
axial skeleton.
The Skeleton of Tetrapods
 Tetrapods must lift themselves to walk on land.
 The first amphibians needed support to replace the
buoyancy of water.
 This added support resulted from the
specializations of the intervertebral disk that
articulate with adjoining vertebrae.
 The intervertebral disk help to hold the vertebral
column together and also absorb shock and provide
joint mobility.
 Bone replaced cartilage in the ribs, which became
more rigid.
 Appendages became elongated for support on hard
surface, and changes in the shoulder enabled the
neck to move more freely.
 The Human Endoskeleton
The human endoskeleton has two
major parts:
➢Axial skeleton – is made up of the
skull, vertebral column, sternum, and
ribs.
➢Appendicular skeleton – is
composed of the appendages, the
pectoral girdle, and the pelvic girdle.
MOVEMENT: NONMUSCULAR MOVEMENT
AND MUSCULAR SYSTEM
Nonmuscular Movement
 All cells have some capacity to move and
changes shape due to their cytoskeleton.
 Protozoan protists move by means of
specific nonmuscular (pseudopodia, flagella,
or cilia) that involve the contractile
proteins actin and myosin.
 Interactions between these proteins are
also responsible for muscle contraction in
animals.
Amoeboid Movement
 The plasma membrane of an amoeba has
adhesive properties since new
pseudopodia attach to the substrate as
they form.
 The plasma membrane also seems to slide
over the underlying layer of cytoplasm
when an amoeba moves.
 The plasma membrane may be “rolling” in
a away that is (roughly) analogous to a
bulldozer track rolling over its wheels.
Ciliary and Flagellar Movement
➢ Cilia – are shorter and more numerous.
➢ Flagella – are long an generally occur singly or
in pairs.
 Ciliary movements are coordinated.
 The epidermis of free-living flatworms and
nemertines is abundantly ciliated.
 The smallest specimen lie at the upper end of
the size range for efficient locomotion using
cilia.
 Larger flatworms have retained ciliary creeping
as the principal means of locomotion, and the
largest animals move by ciliary creeping are the
nemertines.
 AN INTRODUCTION TO ANIMAL
MUSCLE
Muscle tissue has three other important
properties:
1. Excitability ( or irritability )
2. Extensibility
3. Elasticity
Animals may have one or more of the
following types of muscle tissue: smooth,
cardiac, and skeletal. The contractile cells of
these tissue is called muscle fibers.
 Smooth muscle – is called involuntary
muscle because higher brain centers do not
control its contractions.
➢ Single nucleus
➢ Spindle shaped
➢ Arranged in a parallel pattern to form sheets
Striated muscle fibers – with single
nuclei are common in invertebrates, but they
occur in adult vertebrates only in the heart,
where they are called cardiac muscle.
Skeletal muscle – a striated muscle, is a
voluntary muscle because the nervous system
consciously controls its contraction
 THE MUSCULAR SYSTEM OF
INVERTEBRATES
A few functional differences among
invertebrates muscle indicate some of the
differences from the vertebrate skeletal
muscle.
The Locomotion of Soft-Bodied
Invertebrates
 Pedal locomotion – move by means of
waves of activity in the muscular system that
applied to the substrate.
 Looping movement – arching
movements are equivalent to the
contraction of longitudinal muscle.
 Polychaete worms move by the alternate
movement of multiple limbs ( parapodia ).
 The water vascular system of
echinoderms provides a unique
means of locomotion.
 Along each canal are reservoir
ampullae and tube feet.
 Terrestrial Locomotion in
Invertebrates: Walking
 They required structural support, and those
that move quickly make use of rigid skeletal
elements that interact with the ground.
 These The limbs are composed of a series of
jointed elements that become progressively less
massive toward the tip.
 Each joint articulated to allow movement in
only one plane.
 The limb plane at the basal joint with the body
can also rotate and this rotation is responsible
for forward movement.
Terrestrial Locomotion in
Invertebrates: Flight
 The physical properties of an arthropods
cuticle are such that true flight evolved
for pterygote insects some 100 million
years ago.
 The basic mechanism for flight has been
modified.
 Present day insects exhibit a wide range
of structural adaptations and mechanism
for flight.
 Terrestrial Locomotion in
Invertebrates: Jumping
Long legs increase the mechanical advantage
of the leg extensor muscle.
 MUSCULAR SYSTEM OF
VERTEBRATES

 Tendons – which are tough, fibrous,

bands or cords, attach skeletal muscle to
the skeleton.
 Myomeres segments – cause the
lateral undulations of the trunk and tail
that produce fish locomotion.
Fish movement based on the myomere
contraction:
1. The muscular forces cause the myomere
segment to rotate rather than constrict.
2. The rotation of cranial and caudal
myomere segments bend the fish’s body
about a point midway between two
segments.
3. Alternate bends of the caudal end of the
body propel the fish forward.
Skeletal Muscle Contraction
 Each skeletal muscle has a pattern alternate
dark and light bands.
 This striation of whole fibers arises from the
alternating dark and light of many smaller,
threadlike myofibrils in each muscle fiber.
➢Myosin
➢Actin
- I band
- A band
➢Sarcomere
➢Cross bridges
 Control of Skeletal Muscle
Contraction
➢ Motor unit
- consist of one motor nerve fiber and all
the muscle fibers with which it communicates.
➢ Neuromuscular junction
- a space separates the specialized end
body of the motor nerve fiber from the
membrane of muscle fiber.
➢ Acethylcholine
-released by the synaptic vesicles in the
nerve ending
➢ Transverse tubules
- conducting paths
➢ The calcium then binds with a regulatory
protein called troponin that is on
another protein called tropomyosin.