THE INTEGUMENT ANDRELATED STRUCTURES Ms. Hendrickson
WHAT IS THE INTEGUMENT?• The Integument is one of the largest and most extensive organ systems in the body. It is composed of all four tissue types, it covers and protects underlying structures and forms a critical barrier between the delicate inner workings of the body and the harsh elements of the external world.
WHERE DO WE FIND IT?• The skin together with related structures, forms the integumentary system or common integument. • This includes hair, hooves, horns, claws, and various skin related glands. • Itincludes the mucous membranes that line the mouth, anus, and nostrils and has a remarkable ability to heal and regenerate.
THE LAYERS OF SKIN• Skin forms two distinct layers: The epidermis and the dermis.• Only the dermis contains blood Epidermis vessels.•A third layer (the hypodermis) is found below the dermis and is Dermis composed primarily of adipose tissues which act as a thermoinsulator.
THE DERMIS• The dermis makes up the greatest portion of the integument and is responsible for most of the structural strength of the skin.• The dermis is highly ﬁbrous• The dermis contains two layers: • The Papillary layer • The Dermal Papillae
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• Pigmentation: SPECIAL FEATURES • Pigmentation is caused by the presence or absence of melanin granules in the armlike extensions of the melanocytes.• Paw Pads: • The feet of many animals are padded and quiet. The pad’s outer surface is the toughest and thickest skin on the body.• Ergots or Chestnuts: • These are dark, horny structures found on the legs of horses, ponies and other members of the equine family.
SPECIAL FEATURES • Planum Nasale: • The top of the nose in cats, dogs, pigs, and sheep is called the planum nasale. • In the cow and horse, the nose is commonly called the muzzle and is technically referred to as the planum nasolabiale.
SPECIAL FEATURES• Cutaneous Pouches in Sheep: • Cutaneous pouches are infoldings of skin found in sheep. They are found in front of the eyes, between the digits above the hooves, and in the groin. • These pouches are technically called infraorbital, interdigital, and inguinal pouches.
RELATED STRUCTURES OF THE INTEGUMENT Hair Glands of the skin Claws and Dewclaws The Hoof Horns
HAIR• For most animals hair is essential for survival. Hair helps in maintaining body temperature.• Animalspossess a variety of hair types: In general, hair has been categorized into three broad groups: • Primary or Guard Hairs • Straight and thicker • Secondary or Wool Type Hairs • Shorter, Wavy and bristled in dogs • Tactile or Sinus Hairs • These are used as probes and feelers
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GLANDS• Two types of sweat glands are apocrine glands, with ducts that connect to hair follicles, and eccrine glands, which empty directly onto the skin surface.• Sweat glands are meant to trap moisture on the skin surface in order to prevent drying out.
CLAWS AND DEWCLAWS• Many animals have claws, which are the hard, often pigmented outer coverings of the distal digits. Claws are important for maintaining good traction while running, walking and climbing and serve as a lifesaving tool for defense and for catching prey.• Dewclaws are the remains of digits that have regressed in the course of evolution. • In dogs, the dewclaw is the ﬁrst digit. • Incattle, pigs and sheep the medial and lateral dewclaws are the second and ﬁfth digits.
THE HOOF• Thetechnical name for the hoof is the Ungula.• Ruminant animals have four hooves per foot, however weight is only carried on two of them.• Bothclaws and hooves rest on underlying sensitive tissue called the corium.
HORNS• Horns are epidermal in origin and are structurally similar to hair.• Hornsgrow continuously throughout the animals life.• Many domesticated animals are dehorned using a variety of instruments available depending on the species and the age of the animal.• Animals can be genetically bred to be horn free. These are called “polled” breeds.
COMPLETE THETEST YOURSELFQUESTIONS AS WELL AS THE SHORT ESSAYQUESTIONS :)