Unifying Concepts of Animal Structure and Function Chapter 20 Unifying Concepts of Animal Structure and Function

Climbing the Walls Spiderman is a familiar character Climbing the Walls Spiderman is a familiar character Known for his ability to climb walls

Geckos, small lizards commonly found in the tropics Geckos, small lizards commonly found in the tropics Can walk up a wall and across ceilings, but how do they do this?

The explanation relates to hairs called setae, on the gecko’s toes The explanation relates to hairs called setae, on the gecko’s toes Containing many split ends called spatulae The ability to “stick” to surfaces Results from attractions between molecules on the spatulae and the surface on which the gecko is crawling Rows of setae on a gecko’s foot Spatulae coming from a single seta

Correlation between structure and function Is one of biology’s most fundamental concepts e.g. integumentary system (human skin)

THE HIERARCHY OF STRUCTURAL ORGANIZATION IN AN ANIMAL Structure fits function in the animal body Anatomy is the study of structure Physiology studies how structures function

The functions of specific structures Result from their specific structures Palm Finger 2 Finger 3 Shaft Barb Barbule Hook Feather structure Wrist Forearm Finger 1 Internal bone structure Figure 20.1

Animal structure has a hierarchy Structure in the living world Animal structure has a hierarchy Structure in the living world Is organized in a series of hierarchical levels 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 Figure 20.2A–E

Organ Organism System Level Level (Chapters 5–20) Organ Level Endocrine Cardiovascular Lymphatic Nervous Respiratory Muscular Digestive Skeletal Urinary Integumentary Reproductive Organ Level The heart Cardiac muscle tissue Atoms in combination Tissue Level (Chapter 4) Heart muscle cell Complex protein molecule Protein filaments Chemical or Molecular Level (Chapter 2) Cellular Level (Chapter 3) Figure 1-1 1 of 7 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Tissues are groups of cells with a common structure and function Tissues are groups of many similar cells that perform a specific function Main types: Epithilial Connective Muscle Nervous

Epithelial tissue covers the body and lines its organs and cavities Epithelial tissue occurs as sheets of closely packed cells That cover surfaces and line the cavities and tubes of internal organs

Epithelial tissue Functions in protection, secretion, and exchange Free surface of epithelium Basement membrane (extracellular matrix) Underlying tissue Cell nuclei A  Simple squamous epithelium      (lining the air sacs of the lung) D  Stratified squamous epithelium      (lining the esophagus) B  Simple cuboidal epithelium      (forming a tube in the kidney) Layers of dead cells Rapidly dividing epithelial cells Colorized SEM E  Stratified squamous epithelium      (human skin) C  Simple columnar epithelium      (lining the intestine) Figure 20.4A–E

Connective tissue binds and supports other tissues The various types of connective tissue Are characterized by sparse cells in an extracellular gel matrix

Connective tissue Binds and supports other tissues Figure 20.5A–F Cartilage- forming cells Matrix D  Cartilage      (at the end of a bone) Central canal Bone- forming cells E  Bone F Blood A  Loose connective tissue      (under the skin) Elastic fibers Collagen fiber Cell Collagen fibers Cell nucleus B  Fibrous connective tissue      (forming a tendon) White blood cells Red blood cell Plasma C  Adipose tissue Fat droplets Figure 20.5A–F

Muscle tissue functions in movement Skeletal muscle is responsible for voluntary body movements Cardiac muscle pumps blood Smooth muscle moves the walls of internal organs such as the stomach

The three types of muscle tissue Unit of muscle contraction Muscle fiber Nucleus A  Skeletal muscle Junction between two cells C  Smooth muscle B  Cardiac muscle Figure 20.6A–C

Nervous tissue forms a communication network The branching neurons of nervous tissue Transmit nerve signals that help control body activities Cell body Nucleus Cell extensions LM 330 Figure 20.7

CONNECTION Artificial tissues have medical uses Artificial tissues Can assist in the healing of several injuries Figure 20.8 CONNECTION

Small intestine (cut open) Several tissues are organized to form an organ Each organ is made of several tissues that together perform specific functions Small intestine (cut open) Lumen Epithelial tissue (columnar epithelium) Connective tissue Smooth muscle tissue (2 layers) Epithelial tissue Figure 20.9

Organ systems work together to perform life functions Each organ system Has one or more functions

The digestive and respiratory systems Gather food and oxygen A  Digestive system Mouth Esophagus Liver Stomach Small intestine Large intestine Anus B  Respiratory system Nasal cavity Larynx Trachea Bronchus Lung Figure 20.10A, B

Overview of the Digestive Tract The Components of the Digestive System and Their Functions Overview of the Digestive Tract Figure 16-1

The circulatory system, aided by the lymphatic system Transports the food and oxygen The immune system Protects the body from infection and cancer C  Circulatory system Heart Blood vessels E  Lymphatic system D  Immune system Bone marrow Thymus Spleen Lymph nodes Lymph vessels Figure 20.10C–E

Overview of the Cardiovascular System Figure 12-1

The Surface Anatomy of the Heart Figure 12-3(a) 1 of 2

The endocrine and nervous systems The excretory system Disposes of certain wastes The endocrine and nervous systems Control body functions F  Excretory system Kidney Ureter Urinary bladder Urethra Pituitary gland Thymus Thyroid gland Testis (male) Adrenal gland Pancreas G  Endocrine system Ovary (female) Figure 20.10F–G

The integumentary system Skeletal and muscular systems Covers and protects the body Skeletal and muscular systems Support and move the body I  Integumentary system Hair Skin Nails Cartilage Bones J  Skeletal system K  Muscular system Skeletal muscles Figure 20.10I–K

The reproductive system Perpetuates the species Female Vas deferens Penis Urethra Testis Prostate gland Male Oviduct Ovary Uterus Vagina L  Reproductive systems Figure 20.10L

Organ Systems in Mammals

CONNECTION New imaging technology reveals the inner body New technologies Enable us to see body organs without surgery CONNECTION

X-rays Can be used for imaging bones and teeth

CT Computed tomography (CT) scans Are excellent diagnostic tools Figure 20.11A Figure 20.11B

MRI Magnetic resonance imaging (MRI) Allows visualization of soft tissues

MRM Magnetic resonance microscopy (MRM) Provides three-dimensional images of very small structures Figure 20.11C

PET Positron-emission tomography (PET) Yields information about metabolic processes at specific locations in the body HEARING WORDS SEEING WORDS SPEAKING WORDS GENERATING WORDS MIN MAX Figure 20.11D

EXCHANGES WITH THE EXTERNAL ENVIRONMENT Structural adaptations enhance exchange between animals and their environment An animal must exchange materials With its environment

Small animals with simple body construction Have enough surface area to meet their cells’ needs Diffusion Two cell layers Mouth Gastrovascular cavity Figure 20.12A

Larger, complex animals Have specialized structures that increase surface area Exchange of materials between blood and body cells Takes place through the interstitial fluid Respiratory system Excretory system Digestive system Circulatory system External environment Food Mouth Animal Body cells Interstitial fluid Anus Unabsorbed matter (feces) Metabolic waste products (urine) Intestine Nutrients CO2 O2 Figure 20.12B

The respiratory system Has an enormous internal surface area Figure 20.12C

Homeostatic mechanisms Animals regulate their internal environment In response to changes in external conditions Animals regulate their internal environment to achieve homeostasis, an internal steady state Homeostatic mechanisms External environment Internal environment Small fluctuations Large fluctuations Figure 20.13A Figure 20.13B

Homeostasis depends on negative feedback Negative feedback mechanisms Keep internal variables fairly constant, with small fluctuations around set points Homeostasis: Internal body temperature of approximately 36–38C Temperature rises above normal Temperature falls below normal Temperature decreases Temperature increases Thermostat shuts off warming mechanisms Blood vessels in skin constrict, minimizing heat loss Thermostat in brain activates warming mechanisms Skeletal muscles rapidly contract, causing shivering, which generates heat Thermostat in brain activates cooling mechanisms Sweat glands secrete sweat that evaporates, cooling body Blood vessels in skin dilate and heat escapes Thermostat shuts off cooling mechanisms Figure 20.14