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

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

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

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

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

LE 20-04 Free surface of epithelium Basement membrane Cell nuclei Underlying tissue Simple squamous epithelium (lung) Stratified squamous epithelium (esophagus) Simple cuboidal epithelium (kidney) Layers of dead cells Rapidly dividing epithelial cells Colorized SEM Stratified squamous epithelium (skin) Simple columnar epithelium (intestine)

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

LE 20-05 Fat droplets Cartilage- forming cells Adipose tissue Matrix nucleus Cartilage (at the end of a bone) Collagen fiber Central canal Fibrous connective tissue (forming a tendon) White blood cells Matrix Cell Bone- forming cells Red blood cell Collagen fiber Elastic fibers Bone Plasma Loose connective tissue (under the skin) Blood

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

LE 20-06 Unit of Muscle muscle Muscle fiber contraction Junction fiber 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

LE 20-07 Cell body Nucleus Cell extensions LM 330

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

LE 20-09 Small intestine Lumen (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

Excretory system Endocrine system Nervous system Integumentary system Skeletal system Muscular system Reproductive systems

Digestive system Mouth Esophagus Liver Stomach Small intestine Large 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

Immune system Lymphatic system Bone marrow Thymus Spleen Lymph nodes 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

Endocrine system Pituitary gland Thyroid gland Thymus Adrenal gland 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

Reproductive system Male Female Prostate gland Vas deferens Oviduct LE 20-10l Reproductive system Male Female Prostate gland Vas deferens Oviduct Urethra Ovary Penis Uterus Testis Vagina

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

External environment Internal environment Homeostatic mechanisms Small 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

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 3638C Temperature increases Thermostat shuts off warming mechanisms Temperature falls below normal Blood vessels in skin constrict, minimizing heat loss Thermostat in brain activates warming mechanisms Skeletal muscles rapidly contract, causing shivering, which generates heat