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THE HIERARCHY OF STRUCTURAL ORGANIZATION IN AN ANIMAL Copyright © 2009 Pearson Education, Inc. 20.1 Structure fits function at all levels of organization in the animal body Anatomy—structure Physiology—function Animals consist of a hierarchy of levels or organization Copyright © 2009 Pearson Education, Inc. 20.2 EVOLUTION CONNECTION: An animal’s form reflects natural selection Sharks, seals, and penguins have streamlined, tapered bodies Video: Galápagos Sea Lion Video: Shark Eating a Seal Copyright © 2009 Pearson Education, Inc. Shark Penguin Seal A Cellular level Muscle cell A Cellular level Muscle cell B Tissue level Muscle tissue A Cellular level Muscle cell B Tissue level Muscle tissue C Organ level Heart A Cellular level Muscle cell B Tissue level Muscle tissue C Organ level Heart D Organ system level Circulatory system A Cellular level Muscle cell B Tissue level Muscle tissue C Organ level Heart D Organ system level Circulatory system E Organism level Many organ systems functioning together 20.3 Tissues are groups of cells with a common structure and function Animals have four main categories of tissues – Epithelial tissue – Connective tissue – Muscle tissue – Nervous tissue Copyright © 2009 Pearson Education, Inc. 20.4 Epithelial tissue covers the body and lines its organs and cavities Epithelial cells come in three shapes – Squamous—like a fried egg – Cuboidal—as tall as they are wide – Columnar—taller than they are wide Copyright © 2009 Pearson Education, Inc. Apical surface of epithelium Basal lamina Cell Underlying nuclei tissue A Simple squamous epithelium (air sacs of the lung) D Pseudostratified ciliated columnar epithelium (respiratory tract) B Simple cuboidal epithelium (kidney) C Simple columnar epithelium (intestine) E Stratified squamous epithelium (esophagus) 20.5 Connective tissue binds and supports other tissues Connective tissue can be grouped into six major types The tissue consists of a matrix which can be hard, semi soft or fluid in which are embedded cells. Copyright © 2009 Pearson Education, Inc. Fat droplets Cartilageforming cells C Adipose tissue Matrix Cell nucleus D Cartilage (at the end of a bone) Collagen fibers Central canal Cell B Fibrous connective tissue (forming a tendon) White blood cells Matrix Collagen fiber Red blood cell Elastic fibers A Loose connective tissue (under the skin) Plasma F Blood E Bone Boneforming cells 20.6 Muscle tissue functions in movement Skeletal muscle causes voluntary movements Cardiac muscle pumps blood Smooth muscle moves walls of internal organs, such as the intestines Copyright © 2009 Pearson Education, Inc. Unit of muscle contraction Muscle fiber Muscle fiber Junction between two cells Nucleus Nucleus Muscle fiber Nucleus B Cardiac muscle A Skeletal muscle C Smooth muscle 20.7 Nervous tissue forms a communication network Neurons carry signals by conducting electrical impulses Supporting cells insulate axons and nourish neurons Copyright © 2009 Pearson Education, Inc. Cell body Nucleus 20.8 Organs are made up of tissues Each tissue performs specific functions The heart has epithelial, connective, and nervous tissues – Epithelia line the heart chambers – Connective tissues make the heart elastic – Neurons regulate contractions Copyright © 2009 Pearson Education, Inc. Small intestine Lumen Epithelial tissue (columnar epithelium) Connective tissue Smooth muscle tissue (2 layers) Connective tissue Epithelial tissue Lumen 20.9 CONNECTION: Bioengineers are learning to produce tissues and organs for transplants Artificial skin Used to heal burns Copyright © 2009 Pearson Education, Inc. 20.11 CONNECTION: New imaging technology reveals the inner body New technologies show body organs without surgery X-rays help to see bones and teeth Copyright © 2009 Pearson Education, Inc. 20.11 CONNECTION: New imaging technology reveals the inner body Magnetic resonance microscopy (MRM) – Provides three-dimensional images of very small structures Copyright © 2009 Pearson Education, Inc. 20.11 CONNECTION: New imaging technology reveals the inner body Positron-emission tomography (PET) – Helps identify metabolic processes at specific body locations Copyright © 2009 Pearson Education, Inc. 20.10 Organ systems work together to perform life’s functions An organ system usually consists of many organs Each organ system has one or more functions Copyright © 2009 Pearson Education, Inc. 20.10 Organ systems work together to perform life’s functions Endocrine system controls body functions Skeletal and muscular systems support and move the body Circulatory system transports the food and oxygen Respiratory system absorbs oxygen and releases carbon dioxide Integumentary system covers and protects the body Copyright © 2009 Pearson Education, Inc. C Circulatory system D Respiratory system Nasal cavity Larynx Trachea Bronchus Lung Heart A Endocrine Hypothalamus system Pituitary gland Thyroid gland Parathyroid gland Ovary (female) B Skeletal system Blood vessels Bone Adrenal gland Cartilage E Muscular system Pancreas Testis (male) Skeletal muscles F Integumentary system Hair Nails Skin 20.10 Organ systems work together to perform life’s functions Excretory system disposes of certain wastes Lymphatic and immune systems protect the body from infection and cancer Reproductive system perpetuates the species Digestive system absorbs food Nervous system controls body functions Copyright © 2009 Pearson Education, Inc. G, H Lymphatic and immune systems K Reproductive system Thymus Bone marrow Spleen Lymph nodes Male Female Lymphatic vessels Seminal vesicles Prostate gland Oviduct Ovary Vas deferens Penis Urethra Testis Uterus Vagina I Urinary system Brain Sense organ Mouth Kidney Ureter Urinary bladder Urethra J Digestive system Spinal cord Esophagus Liver Stomach Small intestine Large intestine Anus L Nervous system Nerves 20.12 The integumentary system protects the body The skin consists of two layers – Epidermis, at the surface – Dermis, inner layer Copyright © 2009 Pearson Education, Inc. Hair Epidermis Sweat pore Muscle Dermis Nerve Sweat gland Hypodermis Adipose tissue Blood vessels Oil gland Hair follicle 20.12 The integumentary system protects the body Skin has many functions – Epidermis – Resists damage – Decreases water loss – Prevents penetration by microbes – Dermis – Sensory information – Synthesis of vitamin D – Temperature regulation Copyright © 2009 Pearson Education, Inc. EXCHANGES WITH THE EXTERNAL ENVIRONMENT Copyright © 2009 Pearson Education, Inc. 20.13 Structural adaptations enhance exchange between animals and their environment Animals must exchange materials with the environment Respiratory system exchanges gases Digestive system acquires food and eliminates wastes Excretory system eliminates metabolic waste Copyright © 2009 Pearson Education, Inc. External environment CO2 O Food 2 Mouth Animal Respiratory system Digestive system Interstitial fluid Heart Nutrients Circulatory system Body cells Urinary system Intestine Anus Unabsorbed matter (feces) Metabolic waste products (urine) 20.13 Structural adaptations enhance exchange between animals and their environment Adaptations that increase surface area promote exchanges with the environment Copyright © 2009 Pearson Education, Inc. 20.14 Animals regulate their internal environment Homeostasis is an internal steady state Copyright © 2009 Pearson Education, Inc. External environment Internal environment Homeostatic mechanisms Large fluctuations Small fluctuations 20.14 Animals regulate their internal environment Humans promote homeostasis by – Adding clothing when we are cold – Drinking water when we are dehydrated – Eating when our calories are running low – Urinating when our bladders are full Copyright © 2009 Pearson Education, Inc. 20.15 Homeostasis depends on negative feedback Negative feedback mechanisms permit only small fluctuations around set points Animation: Negative Feedback Animation: Positive Feedback Copyright © 2009 Pearson Education, Inc. Sweat glands secrete sweat that evaporates, cooling body Thermostat in brain activates cooling mechanisms Blood vessels in skin dilate and heat escapes Temperature decreases Thermostat shuts off cooling mechanisms Temperature rises above normal Homeostasis: Internal body temperature of approximately 36–38°C Temperature increases Thermostat shuts off warming mechanisms Temperature falls below normal Blood vessels in skin constrict, minimizing heat loss Skeletal muscles rapidly contract, causing shivering, which generates heat Thermostat in brain activates warming mechanisms Tissue Function Structure Epithelial (20.4) Connective (20.5) Muscle (20.6) Nervous (20.7) Sheets of closely packed cells Sparse cells in extracellular matrix Long cells (fibers) with contractile proteins Neurons with branching extensions Protection, exchange, secretion Binding and support of other tissues Movement of body parts Transmission of nerve signals a. b. c. d. e. You should now be able to 1. Explain the relationship between anatomy and physiology 2. Describe the structural hierarchy of the body from cell to organism 3. Explain how an animal’s form is influenced by its environment 4. Describe an example of convergent evolution 5. Describe the general structures and functions of the major tissues of the human body Copyright © 2009 Pearson Education, Inc. You should now be able to 6. Describe several recent advances of bioengineering 7. List and describe the functions of the major systems of the body 8. Explain how materials are exchanged between an organism and its environment 9. Define homeostasis and describe several examples Copyright © 2009 Pearson Education, Inc.