Chapter 4 The Integumentary System and Body Membranes HAP Susan Chabot Lemon Bay High School

Classification of Body Membranes Epithelial Membranes –Cutaneous Membranes = The Skin –Mucous Membranes –Serous Membranes Connective Tissue Membranes –Synovial Membranes

Cutaneous Membranes The Skin

Mucous Membranes Lines body cavities that open to the outside, such as THOSE OF HOLLOW ORGANS of the RESPIRATORY, DIGESTIVE, URINARY, REPRODUCTIVE systems. Adapted for ABSORPTION or SECRETION The lining of the RESPIRATORY and DIGESTIVE tracts secrete large amounts of Protective, lubricating mucus.

Serous Membranes Lines body cavities that are closed to the exterior. Occur in pairs –Parietal: lines the wall of the ventral body cavity. –Visceral: covers the outside of the organ in that cavity. Serous Fluid: thin, watery fluid secreted by the membranes. Function/Importance of Serous Fluid: allows the organs to slide easily across one another without creating friction.

Synovial Membranes Composed of soft connective tissue Contain NO epithelial cells Line the capsules surrounding joints Provides smooth, lubricating fluid to cushion during muscle movement.

Cutaneous Membranes: The Skin Functions Protection from –Mechanical Damage –Chemical Damage –Bacterial Damage –Ultraviolet Radiation –Temperature Damage –Desiccation/Drying out Temperature control: sweat and goosebumps Excretion of urea and uric acid Synthesis of vitamin D

Layers of The Skin

EPIDERMIS Composed of 5 Layers/strata Innermost – Stratum basale = dividing layer S. spinosum S. granulosum S. lucidum Outermost – S. corneum CHARACTERISTICS Avascular – lacks rich blood supply Most cells are keratinocytes that produce KERATIN Average person sheds 40 pounds of skin in a lifetime Completely new epidermis every 25 – 45 days Melanin production is performed by MELANOCYTES in the s. basale during UV exposure.

DERMIS AKA hide Strong and elastic Made of dense fibrous connective tissue

2 Regions of the Dermis Papillary layer = Most superficial layer of the dermis Dermal papillae attaches DERMIS to s. basale –Forms fingerprints which provide gripping action for fingers Provides nourishment to the s. basale to keep those cells dividing. Reticular layer = Deepest layer of the dermis Contains blood vessels, sweat and oil glands, and pressure receptors. Phagocytes prevent bacteria from entering interior of body –NONSPECIFIC Collagen (protein) provides toughness for attachment Elastin (protein) provides flexibility and elasticity. Maintains body temperature by promoting sweat production and release and contraction of muscles for goosebumps.

HYPODERMIS Made of adipose tissue = FAT Deepest layer of the skin Anchors skin to underlying tissues/organs. Provides shock absorption and insulation

NORMAL Skin Pigments 3 main pigments contribute to skin color Melanin: yellow, reddish brown, dark brown, black. Protection from UV light. Carotene: orange-yellow fat soluble vitamin that can be stored in adipose tissue. Hemoglobin: red; found in red blood cells. The more blood in the area, the more red the skin appears.

ABNORMAL Skin Coloration Cyanosis: blue cast to skin due to low blood oxygen levels or poor circulation. Erythema: redness due to blushing, inflammation, fever, high blood pressure Pallor: pale skin due to anemia (low RBC), low blood pressure, loss of blood flow. Jaundice: yellow cast due to bile build up; signifies liver damage Bruises: loss of blood due to injury. Color changes to bruise occur as pigments are broken down.

Albinism Vitligo Cyanosis ErythemaJaundice

Cutaneous Glands Exocrine Glands Secrete products onto surface of epithelium through ducts. 2 Main types –Sebaceous glands AKA Oil Glands –Sudoriferous glands AKA Sweat Glands

Sebaceous Glands OIL GLANDS Found all over the skin except palms and soles Empty into hair follicle Sebum: product of sebaceous glands –Acts as lubricant; keeps skin soft –Kills bacteria

Sudoriferous Glands SWEAT GLANDS 2.5 million per person, found ALL OVER the body Eccrine/Merocrine = most numerous and widespread. –Produces sweat –Highly efficient temp control mechanism –Sweat: mostly salt water and some wastes. Weak acidic pH from 4-6 Can lose up to 7 liters of sweat on a hot day. Apocrine –Only found in axillary and genital regions –Only becomes puberty. –Odorless but bacteria feed off the oily secretion producing an odor.