© 2012 Pearson Education, Inc. Organs and Organ Systems Perform Complex Functions Organs –Contain two or more tissue types joined together; perform specific functions Organ systems –Groups of organs that perform a common function –Examples Digestive system: mouth, throat, stomach, intestines, and liver Lymphatic system: lymph nodes, tonsils, and spleen

© 2012 Pearson Education, Inc. Body Cavities Anterior cavity –Thoracic cavity Two pleural cavities Pericardial cavity –Abdominal cavity Posterior cavity –Cranial cavity –Spinal cavity Tissue membranes (serous membranes) line body cavities

© 2012 Pearson Education, Inc. Figure 4.8 Pelvic cavity Abdominal cavity Anterior cavity Diaphragm separates thoracic and abdominal cavities Pleural cavity Pericardial cavity Thoracic cavity Posterior cavity Vertebral canal Cranial cavity

© 2012 Pearson Education, Inc. Membranes cover the surface of the body, line body cavities, and cover organs

© 2012 Pearson Education, Inc. Tissue Membranes Serous membrane: reduces friction between organs Mucous membrane: lubricates surface, captures debris Synovial membrane: lines spaces in movable joints Cutaneous membrane: skin

© 2012 Pearson Education, Inc. The Skin as an Organ System The proper name is integumentary system Includes skin, hair, nails, glands Functions –Prevents dehydration –Protects from injury –Serves as defense against microorganisms –Regulates body temperature –Makes vitamin D –Provides sensation

© 2012 Pearson Education, Inc. Figure 4.10 ReceptorsNerve Sweat gland Adipose tissue Smooth muscle Vein Artery Sebaceous gland Hypodermis Dermis Epidermis Small blood vessels Hair shaft Free nerve endings Hair root Hair follicle

© 2012 Pearson Education, Inc. Skin Consists of Epidermis and Dermis Epidermis –Outer layer –Stratified squamous epithelial cells –No blood vessels –Two major cell types Specialized keratinocytes Melanocytes

© 2012 Pearson Education, Inc. Figure 4.11 Dead cells of epidermis Living cells of epidermis Dermis with blood vessel Keratinocyte containing melanin Melanocyte containing melanin granules Dividing keratinocyte (basal cell) Basement membrane Blood vessel

© 2012 Pearson Education, Inc. Skin Consists of Epidermis and Dermis Dermis –Lies underneath the epidermis –Supports tissues –Fibers Collagen Elastic –Cells Fibroblasts Mast cells White blood cells Fat cells

© 2012 Pearson Education, Inc. Accessory Structures of Dermis Hair –Shaft –Follicle Smooth muscle –Attached to hair follicle, raises hair to upright position Oil glands/sebaceous glands –Secretion moistens and softens skin

© 2012 Pearson Education, Inc. Accessory Structures of Dermis Sweat glands –Secrete sweat, help in temperature regulation Blood vessels –Supply nutrients, remove waste, assist in temperature regulation Sensory nerve endings –Detect heat, cold, touch, deep pressure, vibration

© 2012 Pearson Education, Inc. Multicellular Organisms Must Maintain Homeostasis Maintenance of relative constancy of the conditions of the internal environment Negative feedback control system: deviations from normal are detected and counteracted Components of a negative feedback control system –Controlled variable –Sensor –Control center –Effector

© 2012 Pearson Education, Inc. Figure 4.12 Controlled variable Higher Set point Lower Effector Sensor Control center a) An increase in the controlled variable causes events that lower the controlled variable toward its set point again. b) A decrease in the controlled variable causes events that raise the controlled variable toward its set point again.

© 2012 Pearson Education, Inc. Figure 4.12a Sensor Effector Control center Controlled variable Higher Set point Lower a) An increase in the controlled variable causes events that lower the controlled variable toward its set point again.

© 2012 Pearson Education, Inc. Figure 4.12b Controlled variable Higher Set point Lower Sensor Effector Control center b) A decrease in the controlled variable causes events that raise the controlled variable toward its set point again.

© 2012 Pearson Education, Inc. Negative Feedback Helps Maintain Core Body Temperature Controlled variable: body temperature Sensors: temperature sensors in skin and internal organs Control center: hypothalamus Effectors –Blood vessels –Sweat glands –Skeletal muscles

© 2012 Pearson Education, Inc. Figure 4.13 Core temperature Higher Set point Higher Lower Constriction of blood vessels in skin (saves heat) Dilation of blood vessels in skin (promotes heat loss) Sensors Shivering (generates heat) Sweating Control center (hypothalamus) Control center (hypothalamus) to

© 2012 Pearson Education, Inc. Homeostasis