PROTECTION, SUPPORT AND MOVEMENT IN

ANIMALS

PROTECTION: INTEGUMENTARY SYSTEM

The Integumentary system’s primary function is to maintain homeostasis. It also protects the body, and its other organs and tissues, from infection, dehydration, sunburn and sudden changes in temperature.

The Integumentary System of animals includes an outer protective body covering called the integument and associated structures and secretions.

• the external covering of an animal• it may refer to the skin, cuticle or

membrane of an organism• protects the animal from

mechanical and chemical injury and invasion by other microorganisms

What is an Integument?

Integumentary Systemof

Invertebrates

Snails, slugs, oysters, and clams are protected by a hard shell made of calcium carbonate secreted by the mantle, a heavy fold of tissue that surrounds the mollusc's internal organs.

Spiders, insects, lobsters and shrimp have bodies covered by an external skeleton, the exoskeleton, which is strong, impermeable, and allows some arthropods to live on land.

The exoskeleton is composed of layers of protein and a tough polysaccharide called chitin, and can be a thick hard armor or a flexible paper-thin covering.

Plasma Membrane• structurally and chemically identical to

the plasma membrane of multicellular organisms

• used as protective covering of some single-celled protozoa

Pellicleoffers further environmental protection and

is a semi rigid structure that transmits the force of cilia or flagella to the entire body of the protozoan as it moves

protective covering of some protozoa

Cuticles• It is the noncellular, hardened or

membranous protective covering of many invertebrates

• consists of chitin and proteins in rigid plates that a flexible membrane links together

Structure of a Paramecium

rests on a basement membraneoutermost layer of epithelial tissue and is

one to several cell thickan integument or outer layer of various

invertebrates

• outer covering of parasitic flukes and tapeworms

Epidermis

Tegument of a tapeworm

Tegument

Integumentary System of Vertebrates

Integumentary System of Vertebrates

Skinvertebrate integument largest organ of the vertebrate body and

grows with the animal Its layers:

1) EpidermisThe outer, protective, nonvascular layer of

the skinIt covers the dermisIt consists of a basal layer of actively

dividing cellsThe epidermis may bear a variety of

specialized structures (Example: feathers, hairs)

Made up of connective tissues, cells and elastic fibers beneath the epidermis

It is thicker than the epidermisDense and fibrous

3) Hypodermis• “below the skin”• Consists of loose connective tissue, adipose

tissue, and nerve endings, separates the skin from deeper tissues

2) Dermis

Skin of Jawless Fishes• Have relatively thick skin• Slime protects the animals from external

parasites• Multicellular slime glands in their skin

secretes large amount of mucous to cover the body surface for protection

Examples: Lampreys and Hagfishes

Lamprey

Hagfish

Skin of Cartilaginous

Fishes• Multi layered and contains mucous and

sensory cells

Denticles– Are bones in the form of placoid scales

found in the dermis– Contains blood vessels and nerves and are

similar to vertebrate teeth• As cartilaginous fishes grow throughout

life, the skin area also increases.

• Once denticles reach maturity, they do not grow; thus, continually wear down and are lost

• Denticles give cartilaginous fishes a sandpaper textureExamples: Sharks, skates and rays

Denticles seen through an electron microscope

Skin of Bony Fishes

• Contains scales- Small flat bony overlapping plates that cover the bodies of fish and composed of dermal bone

Examples: Tuna and Seahorses

Skin of Amphibians• Consists of a stratified epidermis and a

dermis containing mucous and serous gland plus pigmentation cells

• Their skin is highly permeable and they us it to obtain both oxygen and water from their environment

• Earliest amphibians were covered by dermal bone scale like their fish ancestors

• Often times their skin is moist

Skin of Reptiles• is comprised of two main layers, the

epidermis and the dermis• Epidermis: Outer layer of the epidermis is

thick, lack glands, and is modified into keratinized scales, scutes (thick scales), beaks, claws, plaques, and spiny crests.

It is completely covered in keratin.  The keratin is composed of many layers of very thin, flat cells

• Dermis: consists of connective tissue. In some reptiles, there may be small

bones called osteoderms. These are what form the distinctive specialized scales on savannah monitors and crocodilians, for example.

• Reptile skin heals much more slowly than mammalian skin, often taking about 6 weeks for the defect to be fully restored.

• The thick keratinized layer resists abrasion, inhibits dehydration and protects like a suit of armor.

Skin of Birds• The epidermis is usually thin and only

two or three cell layers thick.• “Thin Skinned”• Outer keratinized layer is often quite soft• The most prominent parts of the

epidermis are the feathers (collectively known as plumage)

• Feathers, provides the strong yet lightweight surface area needed for powered, aerodynamic flight.

• They also serve as insulation, trapping pockets of air to help birds conserve their body heat.

• The varied patterns, colors, textures, and shapes of feathers help birds to signal their age, sex, social status, and species identity to one another.

Skin of Mammals• Notable features of mammalian skin :

HairA greater variety of epidermal glands

than in any other vertebrate classA highly stratified, cornified epidermisA dermis many times thicker than the

epidermis

• The skin of mammals is constructed of two layers, a superficial nonvascular epidermis and an inner layer, the dermis or corium. Epidermis

o is composed of stratified squamous epithelium and consists of several layers of a variety of cells.

othe cells pushed toward the surface ,from the deepest layer of the epidermis, dies and becomes keratinized.

oKeratinized cells make up the outer skin layer called stratum corneum.

Dermis The thickest portion of mammalian skin is

composed of dermis which contains blood vessels, lymphatic vessels, nerve endings, hair follicles, small muscles and glands.

• HypodermisIn mammals, it consists of loose connective

tissue, adipose tissue and skeletal muscles. Adipose tissue stores energy in the form of fat and provides insulation in cold environment.

The Structure of the Mammal’s Skin

Skin of Mammals: Glands• Sudoriferous glands (Sweat

Glands)

They are distributed over most of the human body surface. These glands secrete sweat by a process called perspiration which helps regulate the body tempera-ture and maintain homeostasis. In some mammals ,sweat glands also produce pheromones.

• Sebaceous glands

are simple glands connected to hair (oil) follicles in the dermis.

They lubricate and protect by secreting sebum. Sebum is permeability

barrier, an emollient and a protective agent against microorganisms.

Sebum also acts as a pheromone.

AppendagesHair is composed of keratin filled cells that

develop from the epidermis. The portion of hair that protrudes from the

skin is the hair shaft and the portion embedded beneath the skin is the root.

The arrector pilli muscle(smooth involuntary muscles) attaches to the connective tissue sheath of hair follicle surrounding the bulb of the hair root.

Arrector Pilli MuscleWhen this muscle contracts, it pulls the follicle

and its hair to an upright/erect position. In human, this is referred to as a ‘goose

bump.’This action helps to warm an animal by

producing an insulating layer of warm air between the erect hair and skin.

If hair is erect because the animal is frightened instead of cold, the erect hair also makes the animal look larger and less vulnerable to attack.

Nails

¨ Like hair, they are modification of the epidermis.

¨ They are flat, horny plates on the dorsal surface of the distal segments of the digits (e.g. finger and toes of primates).

¨ Other mammals have claws and hooves. ¨ Other keratinized derivatives of mammalian

skin are horns and the baleen plates of the tooth less whales.

SUPPORT: SKELETAL SYSTEM

There are 3 kinds of Skeletons:

A. Fluid Hydrostatic Skeletons / Hydroskeleton

(Gr. Hydro, water + statikos, to stand)A core of fluid (such as blood) surrounded

by a tension-resistant sheath of longitudinal and/or circular muscles

B. Rigid Exoskeletonsª (Gr. Exo , outside + skeleton)ª Have loco motor functions because they

provide sites for muscle attachment and counter forces for muscle movements

ª Support and protect the body, but these are secondary functions

C. Rigid Endoskeletons (Gr. Endo, within + skeleton) A skeleton that lies beneath the surface of

the body

The Skeletal System

of Vertebrates* An endoskeleton enclosed by other body

tissues* Consists of 2 main types of supportive

tissues :1. Cartilage

A specialized type of connective tissue that: provides a site for muscle attachmentaids in movement at jointsprovides supporttransmits the force of muscular contraction

from one part of the body to another during movement

2. Bone or Osseous TissueA specialized connective tissue that:

◊ provides a point of attachment for muscles ◊ transmits the force of muscular contraction

form one part of the body to another during movement

Skeleton of Fishes

Most jawed fishes have an axial skeleton that includes a notochord, ribs, and cartilaginous or bony vertebrae.

Skeleton of Tetrapods• Tetrapod endoskeleton become

modified for support on land.

Human EndoskeletonHas two major parts :• Axial Skeleton

– Made up of the skull, vertebral column, sternum, and ribs

• Appendicular Skeleton

- Composed of the appendages, pectoral girdle, and pelvic girdles

MOVEMENT: MUSCULAR SYSTEMMOVEMENT: MUSCULAR SYSTEM

Nonmuscular Movement and Muscular Movement

Movement is a characteristic of certain cells, protists, and animals

4 cell types that contribute movement:• Amoeboid cells• Flagellated cells• Ciliated cells• Muscle cells

Muscle Cells

– Smooth Muscles / involuntary muscles• Higher brains do not control its

contractions– Cardiac Muscles

• Involuntary• have a single nucleus and are striated

– Skeletal Muscles/ Striated Muscle• A voluntary muscle• The nervous system consciously controls

its contractions

Nonmuscular Movement• It is from the basic framework of the

cell that specialized contractile mechanisms emerged

The Muscular System of Invertebrates

Locomotion of Soft-Bodied Invertebrates

• Pedal locomotion– Can mover a firm substratum

Examples: flatworms, cnidarians, gastropod molluscs

• Looping MovementLeeches : have interior and posterior

sucker that provide alternating temporary point of attachment

Lepidoteran Caterpillars: arching movements are equivalent to the contraction of longitudinal muscles

• Water-Vascular SystemStar Fish: along each canal are

reservoir ampullae and tube feet. The tube feet extend by hydraulic pressure and can perform simple step-like motions

Terrestrial Locomotion in Invertebrates: Walking

• Has flexible joints, tendons, and muscles that attach rigid skeletal cuticle and form limbs

• Examples: arthropods –Crabs : sideward–Lobsters, spider : forwards

Terrestrial Locomotion in Invertebrates: Flight• Muscles changing the shape of the thorax

cause wings to move up and down

• An insect must exert a force against the ground sufficient to impart a take-off velocity greater than its weight

• Examples: Fleas, Grasshoppers, Leafhoppers

Terrestrial Locomotion in Invertebrates: Jumping

The Muscular System of Vertebrates• Provides sites for skeletal

muscles to attach• Tendons : tough, fibrous

bands or cords, attach skeletal muscles to the skeletons

Structure of Skeletal Muscle Tissuea. A skeletal muscle in the forearm consists of

many muscle fibers (cells)b. Bundled inside a connective tissue sheathc. A skeletal muscle fiber contains many

myofibrilsd. Myofibrils consists of functional units called

sarcomerese. The characteristics striations of a

sarcomeres are due to the arrangement of actin and myosin filaments

References

Book: Miller, S. and Harley, J. (2005). Zoology. Avenue of

the Americas, New York. McGraw-Hill Companies, Inc.

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