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Chapter 20 Unifying Concepts of Animal Structure and Function PowerPoint Lectures for Biology: Concepts and Connections, Fifth Edition – Campbell, Reece, Taylor, and Simon Lectures by Chris Romero Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Climbing the Walls • Like Spiderman, geckos can walk up a wall and across ceilings • The gecko's ability to "stick" to surfaces results from special structural adaptations of its body – Setae, hairs made of protein on the gecko's toes, contain many spatulae – Molecules on the spatulae are attracted to molecules on the walking surface • The correlation between structure and function is an overarching concept of biology Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings THE HIERARCHY OF STRUCTURAL ORGANIZATION IN AN ANIMAL 20.1 Structure fits function in the animal body • Anatomy is the study of structure • Physiology studies how structures function • The functions of the various parts of the body result from their specific structures – Example: Flight apparatus of birds provides strength, support, insulation, stability, minimal weight Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 20-01 Forearm Wrist Finger 1 Internal bone structure Palm Shaft Finger 2 Finger 3 Shaft Feather structure Barb Barbule Hook 20.2 Animal structure has a hierarchy • Structure in the living world is organized in a series of hierarchical levels – Cell: smallest independent unit of life – Tissue: integrated group of cells that perform a specific function – Organ: two or more types of tissues that together perform a specific task – Organ system: multiple organs that together perform a vital body function – Organism: integrated unit made up of a number of organ systems functioning together Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 20-02 Cellular level Muscle cell Tissue level Muscle tissue Organ level Heart Organ system level Circulatory system Organism level Many organ systems functioning together 20.3 Tissues are groups of cells with a common structure and function • The cells composing a tissue are specialized to perform a specific function • In almost all animals, most body cells are organized into four main categories of tissues – Epithelial – Connective – Muscle – Nervous Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 20.4 Epithelial tissue covers the body and lines its organs and cavities • Epithelial tissue occurs as sheets of closely packed cells anchored to underlying tissues by a basement membrane • Categories of epithelial tissues – Simple: single layer of cells – Stratified: multiple layers of cells – Shapes: squamous, cuboidal, or columnar • Epithelial tissue functions in protection, secretion, and exchange Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 20-04 Free surface of epithelium Basement membrane Cell Underlying nuclei tissue Simple squamous epithelium (lung) Simple cuboidal epithelium (kidney) Stratified squamous epithelium (esophagus) Layers of dead cells Rapidly dividing epithelial cells Simple columnar epithelium (intestine) Stratified squamous epithelium (skin) 20.5 Connective tissue binds and supports other tissues • The various types of connective tissue consist of sparse cells in an extracellular gel matrix – Loose connective tissue – Fibrous connective tissue – Adipose tissue – Cartilage – Bone – Blood Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 20-05 Fat droplets Cartilageforming cells Adipose tissue Cell nucleus Matrix Cartilage (at the end of a bone) Collagen fiber Fibrous connective tissue (forming a tendon) Cell Collagen fiber Elastic fibers Central canal White blood cells Matrix Red blood cell Bone Plasma Loose connective tissue (under the skin) Blood Boneforming cells 20.6 Muscle tissue functions in movement • Muscle tissue consists of bundles of long cells called muscle fibers – Skeletal muscle is responsible for voluntary body movements – Cardiac muscle forms the contractile tissue of the heart – Smooth muscle moves the walls of internal organs such as the stomach, bladder, and arteries Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 20-06 Unit of muscle contraction Muscle fiber Muscle fiber Junction between two cells Nucleus Nucleus Muscle fiber Nucleus Cardiac muscle Skeletal muscle Smooth muscle 20.7 Nervous tissue forms a communication network • Nervous tissue senses stimuli and rapidly transmits information through the body • The neuron is the structural and functional unit of nervous tissue – Specialized to conduct electrical impulses – Consists of cell body, axon, and dendrites – Nourished by supporting cells Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 20-07 Cell body Nucleus LM 330 Cell extensions CONNECTION 20.8 Artificial tissues have medical uses • Many, but not all, body tissues are self-repairing • Artificial tissues can assist in the healing of tissues that cannot recover on their own – Skin – Cartilage, teeth (under study) Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 20.9 Organs are made up of tissues • Each organ is made of several tissues that collectively perform specific functions – In some organs, tissues are arranged in layers • An organ performs functions that none of its component tissues could carry out alone Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 20-09 Lumen Small intestine (cut open) Lumen Epithelial tissue (columnar epithelium) Connective tissue Smooth muscle tissue (2 layers) Connective tissue Epithelial tissue 20.10 Organ systems work together to perform life functions • There are twelve major organ systems in vertebrate animals – Digestive system – Respiratory system – Circulatory system – Immune system – Lymphatic system Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings – Excretory system – Endocrine system – Nervous system – Integumentary system – Skeletal system – Muscular system – Reproductive systems Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 20-10a Digestive system Mouth Esophagus Liver Stomach Small intestine Large intestine Anus LE 20-10b Respiratory system Nasal cavity Larynx Trachea Bronchus Lung LE 20-10c Circulatory system Heart Blood vessels LE 20-10d-e Immune system Lymphatic system Bone marrow Thymus Spleen Lymph nodes Lymph vessels LE 20-10f Excretory system Kidney Ureter Urinary bladder Urethra LE 20-10g Endocrine system Pituitary gland Thyroid gland Thymus Adrenal gland Pancreas Testis (male) Ovary (female) LE 20-10h Nervous system Brain Sense organ Spinal cord Nerves LE 20-10i Integumentary system Hair Skin Nails LE 20-10j Skeletal system Cartilage Bones LE 20-10k Muscular system Skeletal muscles LE 20-10l Reproductive system Male Female Prostate gland Vas deferens Urethra Penis Testis Oviduct Ovary Uterus Vagina CONNECTION 20.11 New imaging technology reveals the inner body • X-Rays – High-energy radiation passes through soft tissue – Hard structures (teeth, bones, tumors) show up most clearly on film – Problems: don't show soft tissue, are only 2D, can cause cancer in large doses Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Computed tomography (CT) – Computer-assisted X-ray technique – Produces images of a series of thin cross sections through the body – Images can be studied individually or combined into 3-D views – Excellent diagnostic tool, especially for abdomen and brain Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Magnetic resonance imaging (MRI) – Uses powerful magnets to align hydrogen atoms in water – Allows visualization of soft tissues; dense structures nearly invisible • Particularly good for detecting problems in nervous tissue surrounded by bone • Magnetic resonance microscopy (MRM) – Provides three-dimensional images of very small structures Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Positron-emission tomography (PET) – Scanner detects radiation taken up during metabolism – Yields information about metabolic processes at specific locations in the body – Most valuable for measuring brain activity • Alzheimer's disease, epilepsy, stroke Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 20-11d MAX HEARING WORDS SEEING WORDS MIN SPEAKING WORDS GENERATING WORDS EXCHANGES WITH THE EXTERNAL ENVIRONMENT 20.12 Structural adaptations enhance exchange between animals and their environment • An animal must exchange materials with its environment – Oxygen and nutrients enter – CO2 and metabolic wastes exit – Only molecules dissolved in water can move across the plasma membrane • In small, simple animals, each cell has enough surface area to meet its needs by direct diffusion and active transport Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 20-12a Mouth Diffusion Diffusion Gastrovascular cavity Two cell layers • Larger, complex animals have less surface area relative to volume – Rely on specialized surfaces for exchanging materials with the environment • Interstitial fluid provides for indirect exchange between blood and body cells • Branching and folding increase surface area of the lungs, intestines, and kidneys Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 20-12b Mouth External environment CO2 O 2 Food Animal Respiratory system Digestive system Interstitial fluid Heart Nutrients Circulatory system Body cells Excretory system Intestine Anus Unabsorbed matter (feces) Metabolic waste products (urine) 20.13 Animals regulate their internal environment • The internal environment of a vertebrate is the interstitial fluid surrounding the cells • In response to changes in external conditions, animals regulate their internal environment to achieve homeostasis, an internal steady state – Homeostasis is a dynamic state with constant small fluctuations Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 20-13b External environment Internal environment Homeostatic mechanisms Small fluctuations Large fluctuations 20.14 Homeostasis depends on negative feedback • In negative feedback, a change in a variable triggers mechanisms that reverse the change • Negative feedback mechanisms keep internal variables fairly constant, with small fluctuations around set points • In animals, most control centers that maintain homeostasis are located in the brain Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 20-14 Sweat glands secrete sweat that evaporates, cooling body Thermostat in brain activates cooling mechanisms Blood vessels in skin dilate and heat escapes Temperature rises above normal Thermostat shuts off cooling mechanisms Temperature decreases Homeostasis: Internal body temperature of approximately 3638C 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 Animation: Negative Feedback Animation: Positive Feedback Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings