The Crayfish

Common name Crayfish PhylumArthropoda; subphylum Crustacea Body Plan Organization Level Organ-systems Symmetry Bilateral Cephalization Present Body Cavity Present Segmentation Present Cephalothorax Internal Systems Movement Four pairs of walking appendages. Five pairs of swimmerets. Support Exoskeleton composed of chitin Body Covering Exoskeleton Nutrition Scavengers; will living and dead material; vegetative and animal. Respiration Possess gills attached to walking legs Circulation Open circulatory system Excretion Rid nitrogenous wastes through green glands located posterior to the antennules Nervous Dorsal ganglia with ventral nerve chord Possesses compound eyes, antennules. Reproduction Regeneration, dioecious

The Integumentary System Hair, Skin, and Nails

Major roles of the Integumentary System ● ● protection ● ●maintenance of normal body temperature ● ●storage (of fat – adipose tissue) ● ●synthesis (of vitamin D) ● ●excretion (of salts, water and wastes in sweat) ● ●sensory perception through receptors in skin

The Skin: Three Major Layers

Did You Know?... At 8-10 pounds, the skin is bodies’ largest organ!

Layer One: The Epidermis   The epidermis is the outer layer of skin. The thickness of the epidermis varies in different types of skin. It is the thinnest on the eyelids at.05 mm and the thickest on palms and soles at 1.5 mm.   Cells of the epidermis are constantly sloughing off and replacing themselves.

The Epidermis’ Five Layers   Cells are shaped like columns at the base and migrate upward, as dead cells are continuously sloughed off at the surface stratum corneum stratum lucidum stratum granulosum stratum spinosum stratum basale cells filled with keratin but allow absorption of water Contains one columnar layer of undifferentiated cells Shape changes to polygonal and begins to synthesize keratin Nuclei are lost, keratin and water-proofing lipids are formed

The Epidermis’ Five Layers   Cells are shaped like columns at the base and migrate upward, as dead cells are continuously sloughed off at the surface stratum corneum stratum lucidum stratum granulosum stratum spinosum stratum basale Contains one columnar layer of undifferentiated cells Shape changes to polygonal and begins to synthesize keratin Nuclei are lost, keratin and water-proofing lipids are formed Only present in thick skin cells filled with keratin but allow absorption of water

Specialized Epidermal Cells   The melanocyte- produces pigment (melanin)   The Langerhans' cell- frontline defense of the immune system in the skin

Layer Two: The Dermis   This layer varies in thickness as well, depending on the area of the body. It is a mere 0.3 mm on the eyelid and 3.0 mm on your back.   The dermis is composed primarily of connective tissue, blood vessels, sweat glands, hair follicles, nerves receptors, and oil glands.

What makes these hairs stand on end? Why?

Can you name structures 1-4?

Layer 3: The Subcutaneous  Also referred to as the “hypodermis,” this layer of the skin is composed primarily of adipose tissue (fat). This layer plays a key role in insulating the body and regulating the temperature of the skin.  The hypodermis can vary significantly in thickness and incorporates larger blood vessels and nerves.

The Nails  Your nails extend from the epidermis and contain a tough protein called keratin.  They play an important role in grasping objects, scratching, and protecting fingers and toes.

The Hair   Also composed of the protein keratin hair acts as an effective insulator between you and the environment.   hair follicles originate in the dermis.

Did You Know?   Hair can grow as little as 0.1 inches per month or as fast as 0.5 inches per month depending on genetics and your diet.

Aging and the integumentary system Marked declines in:   Cell division in stratum basale   Melanocyte production   Glandular activity   Hair follicle function   Elastic fiber function in dermis   Blood supply to skin   Rate of repair

Disorders of the skin Lesions and tumors Infections (bacterial, viral, fungal, parasitic) Inflammatory reactions and allergies Genetic diseases Acne

Anatomy of a Pimple