Lecture notes including Bacterial Symbionts of animals, Animal form, function, and physiology, and Animal Homeostasis, water and food.
Lecture notes including Bacterial Symbionts of animals, Animal form, function, and physiology, and Animal Homeostasis, water and food. ECOL 182R
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This 14 page Class Notes was uploaded by Camille Hizon on Monday February 29, 2016. The Class Notes belongs to ECOL 182R at University of Arizona taught by Bonine, Hunter, Martinez in Spring 2016. Since its upload, it has received 106 views. For similar materials see Introductory Biology II in Science at University of Arizona.
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Date Created: 02/29/16
Animal Form, Function, and Physiology I. Introduction A. Animal structure is fundamentally related to function B. Animals are generally studied through their anatomy and physiology 1. Anatomy the study of an organism’s physical structure 2. Physiology the study of how the physical structures in an organism function C. Both are iverse! II. Anatomy A. Anatomy: Physical structure (akform) of an organism/and or its components III. Physiology A. refers to “nature, origin”, “knowledge” B. Definition: study of the mechanical, physical, and biocheunctions f living organisms. IV. Tissues, Organs, and Systems A. If a structure found in an animadaptive 1. The structure’s size, shape, or composition will correlate w/ its function 2. Ex: beak size and shape in ground finches on the Galapagos Islands B. If amutant allele alters the size and shape of a structure to make function more efficient 1. Individuals with that allele produce more offspring 2. Allele will increase in frequency over time V. Structure and Function at Cellular and Molecular Levels A. Correlations between form and function begin at the molecular level 1. Ex: protein shape correlates with protein role as enzymes, structural components of the cell, or transporters B. Similar function between structure and function occur atcellular level 1. Ex: cells that secrete digestive enzymes contain a lot of rough ER and Golgi bodies C. Likewise, cell shape and function correlate 1. Absorptive cells have a larsurface area. VI. Tissues are Groups of Cells that Function as a Unit A. Animals are multicellular their bodies contain distinct types of cells that are specialized for different functions. B. A tissueis a group of similar cells that function as a unit 1. Embryonic tissues give rise our adult tissue types a) Connective b) Nervous c) Muscle d) Epithelial C. Connective Tissue 1. Consists of cells loosely arranged in a liquid, jellylikeatrix. d m 2. Matrix comprises extracellular fibers and other materials 3. Is secreted by the connective tissue cells themselves 4. The nature of the matrix determines the nature of the connective tissue 5. Loose connective tissue contains an array of fibrous proteins in a soft matrix a) Examples include adipose and fat tissue 6. Dense connective tissue found in the tendons and ligaments; connects muscles, bones, and organs 7. Supporting connective tissue has a firm extracellular matrix; includes bone and cartilage 8. Fluid connective tissu cells surrounded by a liquid extracellular matrix a) Ex: blood contains various cell types and has a specialized extracellular matrix called plasma D. Nervous Tissue 1. Nervous tissue consists of nerve celleurons and several types of supporting cells 2. Most neurons have two distinct types of projections from the cell body, where the nucleus is located a) Short, branching dendrites, which transfer electrical signals from other cells to the cell body b) Long axons, which carry electrical signals from the cell body to other cells E. Muscle Tissue 1. A key innovation in the evolution of animals like nervous tissue, it appears in no other lineage a) Functions in movement 2. Three types: a) Skeletalmuscle b) Cardiac muscle c) smooth muscle F. Epithelial Tissue 1. Epithelial tissue(epithelia) are tissues that cover the outside of the body,ine the surfacesof organs, and form glands 2. An organ is a structure that serves a specialized function and consists of several tissues. 3. A gland is a group of cells that secrete specific molecules or solutions 4. Epithelia carry out several functions a) Protection b) Transport of water and nutrients 5. Epithelial cells typically form layers of closely packed cells 6. All epithelial tissue has a polarity a) The picalside faces away from other tissues b) The asolateralside faces the animal’s interior (1) Thebasal laminaconnects the epithelial ot the connective tissue c) The apical and basolateral sides of an epithelium have distinct structures and functions G. Functions of Apical and Basolateral Epithelia 1. The apical side of an epithelium generaines organs and secretes mucus. a) An example of this is the lining of the esophagus b) Cells are actively undergoing mitosis 2. Basolateral side links the apical to the basal lamina H. Organs and Organ Systems 1. Cells with similar functions are organized into tissues 2. tissues are organized into structures called organs 3. organs are part oorgan systems which consist of groups of tissues and organs that work together to perform one or more functions I. Form, Function, and Adaptation 1. Biologists who study animal anatomy and physiology are studying adaptations 2. Heritable trait allow individuals to survive and reproduce in a certain environment better than individuals that lack those traits 3. Adaptation results from evolution by natural selection VII. The Role of Fitness TradeOffs A. Trade Offs inescapable compromises between traits 1. Ex: qualityand quantity f offspring B. Researchers investigated the predicted tradeoff between egg size and egg number (clutch size) by manipulating these parameterrickets 1. mating in crickets involves a behavioral adaptation 2. their results showed that such tradeoffs do exist VIII. Adaptation and Acclimation A. Adaptation is a genetic change that occurs over generations in response to natural selection in a population B. Acclimatization, or acclimation 1. A phenotypic change that occurs in an individual 2. In response to a shortterm change nvironmental conditions 3. Acclimation often is applied to change that take place in the laboratory setting C. Allometry 1. Which animal was bigger in real life? 2. Isometry (1:1) is rare D. What are effects of changing body size among species? How does SA/V ratio change as we consider larger and larger species? 1. How do things change with body size? a) Allometry E. Surface Area/Volume Relationships: Theory 1. The cell surface areadetermines the rate at which gases and nutrients diffuse across the membrane 2. The cell volume determines the rate of diffusion a) As a cell gets larger, its volume increases much faster than its surface area does b) The physiological activity can be measured as thetabolic rate 3. Volume increases faster han surface area as animals become longer (bigger) 4. Metabolic rate the rate at which oxygen and energy are consumed a) Often measured as oxygen consumption per unit time b) The consumption of energy is measured as the basal metabolic rate (BMR) c) BMR is the rate at which an animal consumes oxygen while at rest with an empty stomach, under normal temperature and moisture conditions d) The BMR is measured in mL of O consumed per gram of body 2 mass per hour F. Comparing Mice and Elephants 1. Small animals have higher BMRs than do large animals a) Ex: an elephant has more mass than a mouse, but a gram of elephant tissue consumes much less energy than a gram of mouse tissue does 2. As an organism’s size increases, its massspecific metabolic rate must decrease a) Or the surface area available for exchange of materials would fail to keep up with the metabolic demands of the organism 3. Pergram metabolic rate isLOWER if animal arger. IX. How Do Animals Regulate Body Temperature? A. Heat exchange is critical in animal physiology 1. overheating can cause proteins to denature 2. protein denature can lead to dehydration 3. low body temperatures can slow down enzyme function and energy production B. Mechanisms of Heat Exchange 1. All animals exchange heat with their environment in four ways: a) Conduction (solidsolid) b) Convection (solidliquid/gas) c) Radiation (no direct contact) d) Evaporation (phase change) C. Variation in Thermoregulation 1. There is also a continuum regarding whether animals hold their body temperature constant 2. Homeotherms keep their body temperature constant 3. Heterothermscan tolerate changes in body temp 4. Many animals lie somewhere in between these two extremes D. Chemical and biological reactions tend toasterat highetemperatures. E. Q10 effec; how much does metabolic rate change with 10C change in temperature? 1. Q10 typically betw2 and 3 X. Variation in Thermoregulation A. Many animals can control their body temperature through process of thermoregulation including 1. obtaining heat 2. holding body temperature constant B. An endotherm produces adequate heat to warm its own tissue C. an ecotherm relies on heat gained from the environment D. humans are endothermi omeotherms XI. How do endotherms and ectotherms differ with respect to metabolic rate? A. Higher for endotherms because they rely own energy reserves for thermoregulation XII. Ectotherms more efficient than endotherms A. Lizard uses 3% of energy of similarsized mammal 1. about 1/10 the metabolic requirements at a given Tb 2. Let Tb decrease at night 3. overall lower activity B. Production vs. maintenanconversion efficien 1.4% mammal vs. 50% lizard. XIII. Torpor vs. Hibernation A. small mammals that inhabit cold climates lose heat rapidly because their surface area is large relative to their volume B. to survive when temperatures are cold, species such as ground squirrels reduce their metabolic rate and allow their temperop. to d C. This results in: 1. Torpor a temporary drop in body temperature 2. Hibernatio a longer drop in body temperature XIV. Saved by Torpor A. Hummingbirds burn energy fa they eat 1.53 times their weight per day B. During torpor, body temp drop almost50℉.Heart rate may slow from 500 beats/min to less than 50. C. Breathing may be intermittent D. While torpor has benefits, theisks al. It takes as long souror the bird to come back into an activeRADE OFF) XV. Endothermy and Ectothermy A. Endotherms warm themselves because their basal metabolic rates are very high 1. heat given off is enough to warm body 2. mammals and birds retain this heat because they have elaborate insulating structures such as feathers or fur B. Ectotherms gain heat directly from environment and generate heat as a byproduct of metabolism 1. generate small amount of heat due to a low metabolic rate C. Endothermy and ectothermy are understood aontrasting adaptive strategie. Like all adaptations, it inradeoffs. D. Endotherms have higher metabolic rates and are considered to bective. E. Ectotherms can thrive with lower food intakes and use a greater proportion of total energy to support reproduction. Bacterial Symbionts of Animals I. Symbiosis A. Symbiosis Intimate association between unrelated organisms B. Includes parasitic (harmful), mutualistic (beneficial) relationships, and ones that are difficult to categorize C. A symbiont is a smaller organism that lives in or on the larger one. D. Microbial symbionts are everywhere (not just in animals), and not just bacteria E. Not all bacteria are germs; skin bacteria protect against infection II. Why are we only learning this now? A. Less than1% of bacteria can be cultured B. Many bacteria look similar, even when using electron microscopes C. We have a limited ability to investigate complex communities of bacteria with just morphology. III. Review A. Polymerase chain reaction (PCR makes lots of DNA outof a very small amount. 1. Short segments of DNA (primers) bind to genes of interest at each end. Then: heating and cooling, a DNA polymerase, and free nucleotides, causes exponential increase in number of copies. a) What’s the value of making lots of DNA out of a very small amount? (1) makes it easier to study 2. DNA sequencing ew techniques relatively inexpensive, makes sequencing a single bacterial gene from thousands of cells affordable. a) Critical technique that changed our ability to understand the mammalian gut flora (the bacteria in the gut) 3. The axenic (NO gut microbes) angnotobiotic (reduced and known number of microbial species) mouse models. a) Why do you think this might have been an important breakthrough? (1) You can start looking at responses to individual components to give you an idea of what these things do and how they function 4. A critical effort to characterize all of the bacteria associated with humans: The Human Microbiome Project a) Sequenced a singlebacterial ribosomal gen16S rDNA) that allows assignment to bacterial group IV. Bacteria ON animals A. Human Skin Bacteria 1. Found about 1000 species of bacter trillion ce most nonpathogenic 2. Amazing variation in the communities, e.g. compare “manubrium” (high chest) with front and forearm completely different bacteria 3. What do they do? a) Bacteria and sweat cause acid environment that makes it more difficult for pathogenic bacteria to establish b) May secrete antimicrobial substances that keep pathogenic bacteria from dominating c) A common theme: pathogens common in/on healthy individuals, not just causing disease d) Ex: Bacteria on beewolves (1) capture bees; nest in sandy soil, put paralyzed bee in burrow larvae feed on bees. When larval beewolves complete development, they spin cocoon, overwinter. Nest is moist: risk bacterial or fungal infection (2) Beewolves carry bacteria on their antennae (a) Actinobacteria (b) Transmitted from mother to offspring (c) secreted in burrow by mother, incorporated into cocoon by larvae (d) each species of beewolf has its own species of bacterium (e) Bacteria live in pockets in antenna, fed by wasp secretions (3) What do you think the bacterium role is? How would you test this idea? (a) You’re more likely to have successful offspring if you have the bacteria. (b) remove actinobacteria so that bacteria can grow and potentially kill of larvae V. Bacteria in animal cells A. Not just in bacteria but lots of viruses, some protists parasitic symbionts( = pathogens) of human cells B. Bacterial cell pathogens are less dangerous now than they were why? C. The bacterium Rickettsia prowazekii is carried by human lice, and causes typhus. D. Typhus 1. very high fever, potentially leading to death 2. epidemics often followed wars and natural disastershere lice density was high 3. During WWI typhus caused 3 million deaths 4. thousands of inmates in Nazi concentration died of typhus 5. Can be effectively treated with antibiotics. E. In insects, many bacteria in cells are then transmitted from mother to offspring in the egg cytoplasm F. They arevertically transmitt(parentoffspring), not horizor lly o contagiously, like a cold, or most diseases we can think of 1. Can we guess anything about the relationship between insect and bacteria from knowing how the bacteria are transmitted? G. Many of these interactions beneficial for both partners (mutualism) 1. Aphids plant sap sucking insects live on a diet that’s mostly sugar water witlow levels omino acidsmany not the kind they need to make proteins 2. They house bacteria in special organ bacteria synthesize essential amino acids 3. Aphids without bactericannot reproduce 4. Aphids and bacteria have evolved together VI. Bacteria in guts A. In “mice and men” 1. Historical (and quite recent) characterization of gut bacteria as commensal” (i.e. beneficial to bacteria) B. In humans 1. What’s in there? a) About 1000 species, 100 trill cells b) we may carrymore bacterial cell than human cells c) about 25 pounds of our weight 2. Where do they come from? a) Birth cana a few species b) Mother’s mil 600 species; in first few years, more and more bacteria are acquired 3. In humans, what do they do? a) Make vitamins, digest complex starches b) Help the gut develop normally c) Help the immune system develop normally d) Keep pathogens from making ussick. e) Many more claims, including roles in autism, reducing stress, etc. C. Communities of bacteria differ: 1. an environmental component(some similarity within a househo d) 2. genetic component (identical twins bacteria more similar than fraternal twins) 3. Differences in bacterial communities between obese and thin people 4. Obese people have more bacteria from the phylum Firmicutes, fewer Bacteroidetes 5. Thin people had the reverse, and a more diverse set 6. Obese people who became thin acquired ahin person’s bacterial community’ 7. Nutrition diffepending on what bacteria one has 8. Ex: study performed in Malawi in 317 pairs of twins a) Of the pairs of twins: (1) 43% both wellnourished (2) 7% both malnourished (3) 50% one wellnourished, one malnourished (4) In cases where twin differed, the gut= community of gut bacteri also differed b) Does this show the gut flora is responsible? 9. Critical experimen mice with gut flora from malnourished children lacked the abilitymake some vitamins and digest complex carbohydrates. 10. Ex: when Jason and Jonah compete in this twinkie eating contest...They may eat the same number of twinkies bet different numbers of calories from them D. Correlative data may not differentiate betause and effect. 1. Does the gut flora in an obese person CAUSE obesity? (causal explanation)? Or does obesity (the different physiological state of an obese person) AFFECT the type of bacteria that thrive in an obese person? 2. What kind of experiment would you like to do? a) one that has a control, manipulated variable, etc 3. Study: a) Collected microbes from guts of human twins, in each case one lean, one obese b) Inserted collection of microbes from each twin into axenic mice c) First result: mice that received flor from obese twin gained weight, ones that received lean twin flora didn’t even though ate similar amounts d) Then wondered what if mice arethe same environment? e) The ‘lean’ bacteraid not transfer or preveweight gain when mice were fed a high fat, low fiber diet (e.g. pelleted pizza and sweet breakfast cereal). But did when the diet was low in saturated fat, high in fruits and vegetables. 4. So should you get a thin roommate to stay thin? a) May need a thin housemate who also eats well.’ 5. What can we conclude from this study? a) Does the study suggest a direct role of the gut flora on tendency to gain weight? b) What role might diet play? c) How much can we extrapolate from mice to people? E. Role of gut bacteria in development 1. the gut lining (epithelium) does not develop correctly in axenic mice 2. among other things, the bacteria influence the number of microvilli, and the intestine's capacityabsorb nutrients 3. Early exposure to microbes may be necessary fcalibrating the immune response to microbes 4. Desired immune response activate for pathogens, not against oneself or harmless bacteria 5. Axenic mice produce abnormallyhigh numbers of killer T cel caused inflammation 6. As adults, more likely to have asthma and inflammatory bowel disease 7. The woman who almost died: a) Likely contracted a pathogenic bacterial infelostridium diffici, in hospital stay Clostridium infections linked with overuse of certain antibiotics, 3 million people infected in US/year. b) Had ongoing diarrhea, cramps, and vomiting for a year antibiotic treatment didn’t help (and helps only 1525% of patients generally) (1) Why might they not have worked? (a) developed resistance c) Eventually got a fecal transplant from her husband tube went down her nose, past the stomach and into the small intestine d) Cured within 24 hours e) Feces: about 50% bacteria f) was initially the cure of last resort 8. Recent clinical trial a) patients with C. difficile infections b) 16 received bowel lavage + fecal transplant, 13 received bowel lavage + antibiotics, and 13 received antibiotics alone 9. Results % of patients cured a) 81% fecal transplant b) 23% on bowel lavage + antibiotics c) 30% patients on antibiotics alone d) 83% cured that were treated with antibiotics first then were given a fecal transplant 10. Interpret the result: Why did just adding lots of bacteria cure the infection? a) Likelyompetition ith otheacteriasuppressed the dominance of C. difficile. 11. Think oantibioticas alarge hammer tremendously, miraculously effective in some cases. 12. For many years, antibiotics have alleviated human diseaseacterial pathogens. 13. Buteven a large hammer is not effective at pounding in a be(i.e. resistant bacteria) Animal Homeostasis: Water and Food I. Water and Food, Animal Homeostasis A. Why did circulatory systemsvolve B. In flatworm, all cells within 1 mm of water. C. No need for a circulatory system II. Homeostasis “the coordinated physiological processes which maintain most of the [constant] states in the organism” III. regulate/maintaistable conditions in tnternalenvironment. IV. Two alternative approaches re: Homeostasis A. conformational homeostasis occurs by conformation to the external environment 1. Ex: body temp of antarctic rock cod close to seawater it lives in B. Regulatory homeostasis requires a physiological mechanisms tadjusts the internal statto keep it within limits that can be tolerated, regardless of the external conditions 1. Ex: dog maintains body temp of 38 degrees C despite outdoor temperatures C. A stable internal environmenofextracellular flumakes complex multicellulaanimals possible D. cells arespecializedfor maintaining parts of the internal environment E. External functions 1. transport of nutrients and waste; maintenance of ion concentrations F. Internal functions 1. circulation, energy storage, movement, and information processing G. Homeostasis external fluctuatiinimized internally V. Epithelium in Achieving homeostasis A. helps maintain physical and chemical conditions inside animal that are relatively constant B. Basic function control the exchange of materials across its surfaces in a way that is consistent with homeostasis 1. Membrane proteins regulate the transport of molecules and ions 2. Homeostasis depends on this regulation of transport VI. Homeostasis and Enzyme Function A. Dependent on enzyme function 1. Enzymes proteins that catalyze chemical reactions within the cells B. Temp, pH, and other physical and chemical conditions have a dramatic effect on the structure and function of enzymes C. Molecules, cells, tissues, organs, and organ systems function at an optimal level when homeostasis occurs VII. The Role of Regulation and Feedback A. To achieve homeostasis, most animals have regulatory systems that constantly monitor internal conditions such as temperature, blood pressure, blood pH, and blood glucose. B. Each variable has asetpoint a normal or target value C. a homeostatic system is based on three general components: 1. a ensor a structure that senses some aspect of the external or internal environment 2. an integrator a component of the nervous system that evaluates the incoming sensory information and decides if a response is necessary to achieve homeostasis 3. an effector any structure that helps restore the desired internal condition VIII. Negative Feedback A. Homeostatic systems are based on egative feedback effectors reduce/oppose the change in internal conditions B. Ex: changes in blood pH, body temp, body pressure IX. Temperature homeostasis in Endotherms A. Thermoregulation is an important aspect of homeostasis in some animals. 1. Neural signals are received by temperature receptors in the skin (the sensors) 2. The hypothalamus (the integrator) interprets the signal 3. The hypothalamus both interprets and responds to changes in blood temperature 4. The body is then returned to the set point X. The Role of HeatShock Proteins A. Within cells, temperature spikes that are dramatic enough to denature proteins may activateeat shock proteins 1. these proteins speed the refolding of proteins a key step in the recovery process XI. Water and Temperature A. How are water and temperature related? B. For terrestrial animalevaporation s an effective cooling mechanism. C. For aquatic animals, it is very difficult to be a different temperature than the water (water has high specific hea D. This is even more difficultwater breathing animals because rate of heat transfer is greater than rate of transfe in water. 2 XII. What are the effects of changing body size among species? A. For example, how does the SA/V ratio change as we consider larger and larger species? 1. Allometry how things change with body size XIII. Metabolism A. Metabolism chemical reactions in the body B. Temperaturedependent rates C. Not 100% efficient, energy lost as heat (not ‘lost’ if used to maintain Tb) D. Anabolic 1. creation, assembly, repair, growth E. Catabolic 1. energy release from complex molecules (carbohydrates, fats, proteins) 2. energy storage in phosphate bonds (ATP) and metabolic intermediates (glucose, lactate) F. Energy Available for: 1. growth, maintenance, reproduction 2. SDA (specific dynamic action) G. Changes during development 1. king salmon undergo a dramatic increase in body mass during development 2. young individuals exchange gas across the body surface and also have rudimentary gills used for gas exchange 3. as the young develop, individuals switch from skinbreathing to gillbreathing H. Adaptations that Increase Surface Area 1. Increases in surface area relative to its volume achieved in three ways: a) Flattening (1) ex: fish gills, have flattened, sheetlike structures called lamellae b) Folding (1) ex: the mammal small intestine has folds called villi c) Branching (1) Small blood vessels called capillaries are highly branched 2. The circulatory system allowed animals to get igger 3. Animals with higher oxygen needs larger diffusion area
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