Unit f: Homeostasis & Unifying Concepts of Biology Unit f: Homeostasis & Unifying Concepts of Biology Chapter 20

Unit f Standards I can describe the structural hierarchy of the body: cell, tissue, organ, organ system and organism I can describe the structure and function of the 4 types of tissues: epithelial, connective, muscle and nervous I can state the structures (organs) of the 12 organ systems I can describe the function of the 12 organ systems I can explain how and why animals regulate their bodies via homeostasis I can provide examples of negative feedback loops at work in the human body and explain why they function to maintain homeostasis

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

A little Hank  Intro to Anatomy and Physiology Tissues Part 1: Intro, Nervous and Muscle Tissues Part 2: Epithelial Tissues Part 3: Connective Tissues Part 4: Types of Connective

THE HIERARCHY OF STRUCTURAL ORGANIZATION IN AN ANIMAL THE HIERARCHY OF STRUCTURAL ORGANIZATION IN AN ANIMAL Correlation between structure and function is one of biology’s most fundamental concepts 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 Palm Finger 2 Finger 3 Shaft Barb Barbule Hook Feather structure Wrist Forearm Finger 1 Internal bone structure Figure 20.1

20.2 Animal structure has a hierarchy 20.2 Animal structure has a hierarchy Structure in the living world is organized in a series of hierarchical levels Muscle cell A  Cellular level B  Tissue level Muscle tissue C  Organ level Heart E  Organism level Many organ systems functioning together D  Organ system level Circulatory system Figure 20.2A–E

20.3 Tissues are groups of many similar cells with a common structure and that perform a specific function 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 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

20.6 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 Figure 20.6A–C 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

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

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

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 Small intestine (cut open) Lumen Epithelial tissue (columnar epithelium) Connective tissue Smooth muscle tissue (2 layers) Epithelial tissue Figure 20.9

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 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 Bozeman: Organ Systems

The immune system protects the body from infection and cancer 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

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 covers and protects the body Skeletal and muscular systems support and move the body I  Integumentary system Hair Skin Nails K  Muscular system Skeletal muscles Cartilage Bones J  Skeletal system 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

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

X-rays 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 20.12 Structural adaptations enhance exchange between animals and their environment Small animals with simple body construction have enough surface area to meet their cells’ needs Diffusion Two cell layers Mouth Gastrovascular cavity

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 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 Homeostatic mechanisms External environment Internal environment Small fluctuations Large fluctuations Figure 20.13B Figure 20.13A Bozeman: Homeostasis

20.14 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

Your Turn!! To help understand the connection between the body systems and homeostasis go to this website: https://ats.doit.wisc.edu/biology/ap/ho/ho.htm and proceed through the 3 topics in order 1. Ben’s Bad Day 2. Ben’s Homeostasis: The Inside Story 3. Does Ben Have Diabetes?