Module 6: The Multicellular Animal Body PDF
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This document details the fundamental concepts of animal form and function, focusing on the organization and structure of multicellular organisms. It explores the relationship between animal structure and its interactions with the environment.
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MODULE 6: THE MULTICELLULAR ANIMAL BODY Interstitial Fluid: In flat animals (e.g. tapeworms), nimal form and function are correlated at all A...
MODULE 6: THE MULTICELLULAR ANIMAL BODY Interstitial Fluid: In flat animals (e.g. tapeworms), nimal form and function are correlated at all A mostcellsareindirectcontactwithitsenvironment levels of organization. = the interstitial fluid of other animals. Anatomy:It is the biological form of an organism. volutionary adaptations of more c E omplex organisms enable sufficient exchange with the hysiology:Itisthebiologicalfunctionsanorganism P environment. performs. Invertebrates,thespacebetweencellsisfilledwith S ize and shape affectthewayananimalinteracts interstitial fluid, which allows for the movement of with its environment.Thebodyplanofananimalis material into and out of cells. programmed by the genome, itself theproductof millions of years of evolution. IERARCHICAL ORGANIZATION OF BODY PLANS H Most animals are composed of specialized cells organized into tissues that have different functions. VOLUTION OF ANIMAL SIZE AND SHAPE E Physicallawsgovernstrength,diffusion,movement, T issues make up organs, which together make up and heat exchange. organ systems. roperties of water limit possible shapes for fast P S ome organs, such as the pancreas, belong to swimming animals. more than one system. s animals increase in size, thicker skeletons are A required for support. onvergent Evolution: results in similar adaptations C of diverse organisms facing the same challenge. In the ocean, fast swimmers have a streamlined fusiform shape. EXCHANGE WITH THE ENVIRONMENT utrients, Waste Products, and Gases: It must be N exchanged across the cell membranes of animal cells. ateofexchange:Shouldbeproportionaltoacell's R EXPLORING STRUCTURE AND FUNCTION IN ANIMAL surfaceareawhileamountofexchangematerialis TISSUES proportional to a cell's volume. Different tissues have different structures that are suited to their functions. S ingle-celled organism living in water hassufficient surface area to carry out all necessary exchange. T issues are classified into four main categories: Epithelial, Connective, Muscle, and Nervous. ulticellular organisms with a saclike b M ody plan have body walls that are only two cells thick, pithelial Tissue: It covers the outside of the body E facilitating diffusion of materials. andlinestheorgansandcavitieswithinthebody.It 9 is a barrier against mechanical injury, pathogen F ibrous ConnectiveTissue:Itisfoundintendons and fluid loss [tight junction]. (attach muscles to bones) and ligaments (connects bones at joints). hape: Be cuboidal (like dice), columnar (like S bricks on end), or squamous (like floor tiles). one: It is mineralized and forms the skeleton. B Bone cells are called Osteocytes. rrangement: May be simple(singlecelllayer), A stratified (multiple tiers of cells), or dipose Tissue: It stores fat for insulation and A pseudostratified (a single layer of cells of fuel. Its cells are called adipocytes. varying length). lood: Blood cells and cell fragments in blood B The Polarity of Epithelia plasma. olarity: It means two different faces. The P artilage: It is a strong and flexible support C Epithelial has two surfaces: Apical surface material. Its cells are called chondrocytes. (outer) and Basal surface. uscleTissue:Itisresponsiblefornearlyalltypesof M onnective Tissue: It mainly binds and supports C bodymovement.Musclecellsconsistoffilamentsof other tissues. It contains sparsely packed cells the proteins actin and myosin, which together scattered throughout an extracellular matrix. The enable muscles to contract. matrix consists of fibers in a liquid, jellylike, or solid foundation. Divided in the vertebrate body into three types: Three Types of Connective Tissue Fiber All of these are made of protein. keletal Muscle (Striated Muscle): S It is responsible for voluntary movement. ollagenous Fibers: It provides strength and C flexibility. mooth Muscle: It is responsible for involuntary S body activities. eticular Fibers: It joins connective tissue to R adjacent tissues. ardiac Muscle:Itisresponsibleforcontraction C of the heart. lastic Fibers: It stretches and snaps back to E their original length, The connective tissue also contains cells, including: Fibroblasts: These secrete the protein of extracellular fibers. Macrophages: These are involved in the immune system. Six Major Types of Connective Tissue ervous Tissue: It functions in the receipt, N processing, and transmission of information. It L oose Connective Tissue: It binds epithelia to contains: underlying tissues and holds organs in place. Neurons, or nerve cells, that transmit nerve impulses Glial cells, or glia (support cells) 10 egulator: It uses internal control mechanisms to R control internal change in the face of external fluctuation. onformer: Itallowsinternalconditionstovarywith C certain external changes. COORDINATION AND CONTROL It is in response to stimuli. It depends on the endocrine system and the nervous system. ndocrine System: It transmits chemical signals E called hormones to receptive cells throughout the body via blood. hormone may affect one or more regions A throughoutthebody[dependingoncellsthathave receptors for it]. ormones are relatively slow acting,butcanhave H OMEOSTASIS H long-lasting effects. Used to maintain a “steady state” or internal balance regardless of external environment. ervous System: It transmits information between N specific locations via the axons. In humans, body temperature, blood pH, and glucose concentration are each maintained at a T he information conveyed depends on a signal’s constant level. pathway, not the type of signal. Nerve signal transmission is very fast. echanisms of Homeostasis M It controls changes in the internal environment. Fluctuations above or belowasetpointserveasa stimulus;thesearedetectedbyasensorandtrigger a response. The response returns the variable to the set point. Feedback Control in Homeostasis egative Feedback: Homeostasis in animals N relies largely on negative feedback, which helps to return a variable to a normal range. ositive Feedback: It amplifies a stimulus and P does not usually contribute to homeostasis in The Chemical Factor animals. nimals may regulate some environmental A variables while conforming to others. 11 oikilotherm: The body temperature P of a poikilothermvarieswith its environment. omeotherm: The body temperature of a H homeotherm is relativelyconstant. lterations in Homeostasis A T he relationship between heat source and body Setpointsandnormalrangescanchangewithage temperatureisnotfixed(thatis,notallpoikilotherms or show cyclic variation. are ectotherms). Ectothermic marinefishesandinvertebrates ircadianRhythm:Inanimalsandplants,itgoverns C inhabit waters with such stable physiological changes that occurroughlyevery24 temperatures. hours. Metabolic activities undergo daily cycles in Bats drop from 40°C to a few degrees response to the circadian clock. above zero when they enter hibernation. alancing Heat Loss and Gain B Organisms exchange heat by four physical processes:radiation,evaporation,convection,and conduction. HEAT REGULATION IN MAMMALS cclimatization: A process by which homeostasis A It often involves the integumentary system (skin, can adjust to changes in the external environment. hair, and nails). irds and mammals can vary their insulation to B F ive adaptations help animals thermoregulate: acclimatize to seasonal temperature changes. insulation, circulatory adaptations, cooling by evaporative heat loss, behavioral responses, and hen temperatures are subzero, someectotherms W adjusting metabolic heat production. produce “antifreeze” compounds to prevent ice formation in their cells. Insulation: A major thermoregulatoryadaptationin mammalsandbirds.Skin,feathers,fur,andblubber omeostaticprocessesforthermoregulationinvolve H heat flow between an animal and its environment. form, function, and behavior irculatory Adaptations: Many endotherms and C T hermoregulation:Itistheprocessbywhichanimals some ectotherms can alter the amount of blood maintainaninternaltemperaturewithinatolerable flowing between the body core and the skin range. (vasodilation and vasoconstriction). ndothermic: Animals can generate heat by E T he arrangement of blood vessels in many marine metabolism; birds and mammals are endotherms. mammals and birds allows for countercurrent exchange. ctothermic: Animals gain heat from external E They transfer heat between fluidsflowingin sources; ectotherms include most invertebrates, opposite directions and thereby reduce fishes, amphibians, and nonavian reptiles. heat loss. Variation in Body Temperature 12 ooling by Evaporative Heat Loss: Many types of C animals lose heat through evaporation of water from their skin. weatingorBathing:Itmoistenstheskin,helping S to cool an animal down. anting: It increases the cooling effect in birds P and many mammals. ehavioral Responses: Both endotherms and B ectotherms use behavioral responses to control body temperature. S ome terrestrial invertebrates have postures that nergy Allocation and Use E minimize or maximize absorption of solar heat. Organisms can be classified by how they obtain chemical energy. oneybeeshuddletogetherduringcoldweatherto H retain heat. utotrophs:Harnesslightenergytobuildenergy-rich A molecules (ex: plants). djusting A Metabolic Heat Production: Thermogenesis istheadjustmentofmetabolicheat eterotrophs: Harvest chemical energy from food H production to maintain body temperature. (ex: animals). T hermogenesis is increasedbymuscleactivitysuch QUANTIFYING ENERGY USE as moving or shivering. etabolic Rate: It is the amount of energy an M hysiological Thermostats P animal uses in a unit of time. Thermoregulation in mammals is controlled by a region of the brain called thehypothalamus. It can be determined by: An animal’s heat loss T he hypothalamus triggers heat loss or heat Theamountofoxygenconsumedorcarbon generating mechanisms. Some ectothermic dioxide produced organisms seek warmer environments to increase Measuring energy content of food their body temperature in response to certain consumed and energy lost in waste infections. products. Metabolic Rate and Thermoregulation asal Metabolic Rate (BMR): Metabolic rate of B an endotherm at rest at a “comfortable” temperature. tandard Metabolic Rate(SMR):Metabolicrate S of an ectotherm at rest at a specific temperature. 13 INFLUENCES ON METABOLIC RATE ctotherms have muchlowermetabolicratesthan E endotherms of a comparable size. ther key factors: age, sex, size, activity, O temperature, and nutrition. Size and Metabolic Rate etabolic rate is proportional tobodymasstothe M power of three quarters (m3/4). S maller animals have higher metabolic rates per gramthan larger animals. igher metabolic rate ⇒ leads toahigheroxygen H delivery rate, breathing rate, heart rate, and greater (relative) blood volume. Activity and Metabolic Rate ctivity greatly affects metabolic A rate for endotherms and ectotherms. Ingeneral,themaximummetabolicrateananimal cansustainisinverselyrelatedtothedurationofthe activity. F or most terrestrial animals, the average daily rate of energy consumption is 2-4 times BMR (endotherms) or SMR (ectotherms). T hefractionofananimal’senergybudgetdevoted toactivitydependsonseveralfactors:environment, behavior, size, and thermoregulation. 14
