© 2012 pearson education, inc. organs and organ systems perform complex functions organs –contain...
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© 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
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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 cavityThoracic
cavity
Posterior cavity
Vertebral canal
Cranial cavity
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• Membranes cover the surface of the body, line body cavities, and cover organs
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Tissue Membranes
• Serous membrane: reduces friction between organs
• Mucous membrane: lubricates surface, captures debris
• Synovial membrane: lines spaces in movable joints
• Cutaneous membrane: skin
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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 4.10ReceptorsNerveSweat gland
Adipose tissue
Smooth muscle
VeinArtery
Sebaceous gland
Hypodermis
Dermis
Epidermis
Small blood vessels
Hair shaft Free nerve endings
Hair root
Hair follicle
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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
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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
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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
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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
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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 variableControlled variable
HigherHigher
Set point Set point
Lower Lower
Effector EffectorSensor Sensor
Control center 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
SensorEffector
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
SensorEffector
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 Core temperature
Higher
Set point Set point
Higher
Lower Lower
Constriction of bloodvessels in skin(saves heat)
Dilation of bloodvessels in skin(promotes heat loss)
SensorsSensors
Shivering(generates heat) Sweating
Control center(hypothalamus)
Control center(hypothalamus)
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