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

20.2 Animal structure has a hierarchy Structure in the living world 20.2 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

20.4 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

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

20.6 Muscle tissue functions in movement Skeletal muscle attaches bones by tendons and is responsible for voluntary movements of the body. Cardiac muscle forms the contractile tissues of the heart. Smooth muscle found on the walls of digestive tract, urinary bladder, arteries, and other internal organs.

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

20.7 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

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

20.10 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 Mouth Nasal cavity Larynx Esophagus Liver Trachea Stomach Bronchus Small intestine Lung Large intestine Anus A  Digestive system B  Respiratory system Figure 20.10A, B

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

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

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

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

20.11 New imaging technology reveals the inner body CONNECTION 20.11 New imaging technology reveals the inner body New technologies Enable us to see body organs without surgery

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 MAX HEARING WORDS SEEING WORDS MIN SPEAKING WORDS GENERATING WORDS Figure 20.11D

EXCHANGES WITH THE EXTERNAL ENVIRONMENT 20.12 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 Mouth Diffusion Two cell layers Diffusion 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 External environment Mouth Food CO2 O2 Animal Respiratory system Digestive system Interstitial fluid Nutrients Circulatory system Body cells Intestine Excretory system Anus Figure 20.12B Unabsorbed matter (feces) Metabolic waste products (urine)

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

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

20.14 Homeostasis depends on negative feedback Negative feedback mechanisms Keep internal variables fairly constant, with small fluctuations around set points 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 Figure 20.14