Zoo-Lec (Sem-1) Integumentary System

integument

external covering of an animal; shows adaptations for the animal’s environment

integumentum

Latin word of origin for integument; meaning cover

protection; support; movement

the three main functions of the integumentary system

surface of exchange of gases, nutrients, and wastes

function of integument; some organisms (amphibians especially) use the skin as a respiratory organ

protection from injury and invasions of microorganisms

function of integument; forms a physical barrier between the external environment (bacteria, chemicals, and temperature) and the internal environment

regulation of body temperature

function of integument; keeping body temperature within limits even when environmental temperature varies (thermoregulation)

reception of environmental stimuli

function of integument; presence of sensory nerve endings that receive and interpret stimuli

prevention of desiccation

function of integument; presence of thick layers and outer lubrication film to avoid extreme moisture loss

desiccation

the state of extreme dryness, or the process of extreme drying

invertebrate

an umbrella term describing animals that neither develop nor retain a vertebral column (commonly known as a spine or backbone)

invertebrate integument

the outer covering of animals that lack a vertebral column; consists of a single layer of columnar epithelial cells (epidermis)

invertebrate epidermis

a single layer of epithelial cells; rests on a thin extracellular layer of collagenous fibers

basement membrane

a thin extracellular layer of collagenous fibers; separates the epidermis from underlying muscles or other tissues

cilia

modified outer layer; present in the epidermis of free-living flatworms (e.g. Platyhelminthes, Turbellaria) that move by ciliary locomotion

epidermal glands

may secrete mucus and noxious chemicals that protect the animal (e.g. Mollusca, Gastropoda) and secrete skeletal materials like calcium carbonate (e.g. Cnidaria, anthozoan hard corals)

syncytial tegument

the epidermis of parasitic flatworms (Cestoidea and Trematoda) that protects against host defenses and aids cestodes (e.g. tapeworms, Cestoda) in the absorption of nutrients from the host digestive tract

cuticle

non-living; possessed by all ecdysozoans; secreted by the epidermis; either collagenous or chitinous; hardened in arthropods; provide protection but restricts growth; is shed periodically

restrict growth

the cuticle provides protection, but they also…

sclerotization

biological processes that cause tissues to become hard and stiff

invertebrate hypodermis

the epidermis when it is overlain by a cuticle; secretes the cuticle

invertebrate dermis

a connective tissue layer below the basement membrane; secretes calcium ossicles that comprise endoskeletal elements in the Echinodermata

proglottid

each segment in the strobila of a tapeworm, containing a complete sexually mature reproductive system

scolex

the head of a tapeworm either in the larva or adult stage from which the proglottids are produced by budding

vertebrate

animals that possess a vertebral column and/or notochord at any point in their lives

vertebrate integument

often simply called skin; with multi-cell layered epidermis

vertebrate epidermis

often comprised of multiple cell layers and is underlain by a basement membrane

vertebrate dermis

comprised of collagenous and other connective tissue fibers and cells

vertebrate hypodermis

in contrast to that described for ecdysozoans, consists of connective tissues (including adipose), nerve endings, and blood vessels; separates the integument from deeper tissues, such as muscle tissue

Petromyzon

adult lamprey

fish epidermis

outer layer that is multilayered and richly supplied with glandular cells

hagfish (class Myxini); lampreys (class Petromyzontida)

fishes with a scaleless integument with mucous-secreting cells

granular cells

contribute to a mucous coat that reduces friction between the water and the surface of the animal

mucous coat

protects against bacteria and other infections

thread cells

found in hagfishes; produce cords of mucus that are secreted through multicellular slime glands

slime

secreted when the hagfish is irritated and discourages predators whose gills may be clogged by copious slime discharge

pheromones

secreted by epidermal cells; communicate danger or other chemical messages to members of the same species

dermally derived scales

absent in hagfishes and lampreys; protect a fish and are oriented in a fashion that reduces friction as the fish swims; present in Chondrichthyes and bony fishes

Chondrichthyes

sharks and their relatives

denticles

present in most Chondrichthyes; small placoid scales arising from and seated in the dermis; comprised of a bone-like calcified matrix called dentine, and each scale projects through the epidermis; wear and are replaced through the life of the fish

placoid

toothlike, being made of dentin with a pointed backward projection of enamel, as in sharks and rays

dentine

a bone-like calcified matrix

enamel

secreted by the epidermis; covers the dentine core

true

true or false: the scales of bony fishes do not lose their covering of epidermal cells

scales

are classified based on structure, but they are all comprised of a layering of dermal bone, dentine, and an epidermally derived layer of enamel

dermal bone; dentine; epidermal-derived layer of enamel

layers within a scale

dermal blood capillaries

associated with the scales of bony fishes; grow throughout the life of a fish; growth patterns produce the rings that are useful in determining the age of a fish