Integumentary System Flashcards
(40 cards)
What are the three layers of skin called? What order from top to bottom are they in?
1) Epidermis, 2) Dermis, 3) Hypodermis
What is the Epidermis?
The top layer of skin, composed of layers of cells, with dividing cells in the lower layers. Top cells are dead with a lot of keratin in them and fall off. Cells deeper in the Epidermis don’t keratinise but can produce melanin.
What is the Dermis?
The second layer of skin, which contains collagen and elastic protein fibres which give skin its strength and elasticity.
What is the Hypodermis?
Attaches the skin to the underlying structures. It consists of fat or adipose tissue.
What is Keratin?
It is a tough, fibrous protein which is resistant and waterproof.
What does Keratin form?
Hair, feathers, scales, nails, claws, hooves and the outer layer of horns and the outermost layer of skin.
What gives skin pigmentation?
Melanin. Melanin producing cells are called melanocytes.
What does the Dermis contain?
At various levels, it contains hair follicles, sweat and sebaceous glands, blood vessels and capillaries, nerves and nerves endings (pain, pressure and temperature).
Why don’t tattoos slough off with dead skin cells?
Tattoo ink is injected into the dermis layer of the skin, which doesn’t slough off.
What is mitosis?
Mitosis of a parent cell produces two daughter cells that are identical to both the parent cell and each other. A chromosome from the parent cell is replicated and a copy of each chromosome goes to each of the daughter cells.
What are the functions of the skin?
Protection, temperature regulation, stimulus reception and vitamin production.
What does the skin protect from?
Minor knocks and bumps, UV rays, microbes, heat loss and water loss.
How does the skin regulate temperature?
Sweating cools the skin, pilo-erection, receptors for temperature, fat, vasodilation or vasoconstriction.
What stimuli does the skin have receptors for?
Touch, pressure, pain, hot and cold.
What are some waste products removed by the skin?
Water and salts.
What role does skin have in sexual attraction?
Pheromones and colouration can attract mates.
What vitamin is produced in the skin? What is its use in the body?
Vitamin D. It is used to build healthy bones.
What is the hypodermis also called?
The subcutaneous layer.
What is mitosis used for?
Growth, repair and body maintenance.
What are calluses and footpads made of?
Thickenings or swellings of the outermost, keratinised layers of the epidermis. Usually present on surfaces subject to wear.
What is a claw? What is the difference between a nail and a claw?
It forms a protection for the top, sides and tip of a terminal toe joint. Beneath the claw there is a growing layer, protected on its base by a fold of skin, from which the claw continually grows outwards. On the under surface is a pad of softer, less keranised tissue, a subunguis, which effects a transition between the claw and the epidermis. A nail is a broadened and flattened claw restricted to the upper surface of the finger or toe.
What is a hoof made of?
It is a shorted and broadened shealth of keratinised material that surrounds the toe tip. It is characteristic of ungulate mammals.
What are horns?
The core of a horn is a spike of bone arising in the dermis and fused with the skull. Sheathing and extending this is a hollow cone of true horn substance, formed by kerantinisation of skin epidermis. Neither core nor sheath is ever shed, and these typical horns, variously curved, are never branched.
What are antlers?
The antlers usually consist solely of bone. During growth it is covered by skin in the form of velvet. An antler is shed annually and tends to be branched, increasingly so in older animals.
