Lesson 26 - Form and Function

26: form and function Friday, March 29, 2024 1:01 PM structure and function are linked • all animals must meet basic needs, but they have evolved many different strategies to do so • variation in phenotype reflects adaptations and tradeoffs ectoderm: epithelial & nerve tissue • epithelial tissue: ○ sheets of cells, vary in shape ○ cover outside, line the inside ○ interact with the environment ○ first line of defense; maintains homeostasis ○ protects the body from some substances while also permitting the entrance of others ○ selective permeability for secretion and gas exchange • nerve tissue: ○ sensing, processing, transmission of information ○ neurons as basic unit • other than vertebrates, some protostomes, any bilaterians, and organisms with radial symmetry may have ectoderm tissues • present in everything except sponges mesoderm: connective & muscle tissue • in bilaterians, less basal species organisms with radial symmetry may have ectoderm tissues • present in everything except sponges mesoderm: connective & muscle tissue • in bilaterians, less basal species • connective: ○ cells scattered in an extracellular matrix ○ found between other tissues ○ very broad ○ ex. tendons, blood, fat/adipose, bones, etc. • muscle: ○ cells made of filaments containing actin & myosin ○ skeletal (a): attach to bone, tendons § ex. biceps ○ smooth (b): involuntary activities § ex. digestive system ○ cardiac (c) heart walls • bilaterians; more derived organisms • mainly organs are derived from mesoderm which of the following tissues is mismatched with one of its organs/organ systems? a. connective - bone b. muscle - stomach walls c. epithelial - blood ○ connective ○ in extracellular matrix d. nerve - spinal cord responding to external environments: • requires communication and feedback between cells, tissues, organs, and environment • endocrine system - hormones ○ changes affect whole body • nervous system - nerve impulses ○ immediate changes, may be localized when the environment changes • acclimatization/acclimation: ○ physiological adjustment in response to change in environment ○ type of phenotypic plasticity § ability of genotypes to produce different phenotypes when exposed to different environmental conditions § developmental (water fleas) § seasonal (change in color of coat) ○ not heritable § phenotypic plasticity is, but not the trait • adaptation: ○ changes in phenotype increasing survival and reproduction ○ heritable managing internal environments • regulator: ○ maintains internal environment when external environment changes • conformer: ○ internal environment changes as external environment changes ○ correlation with the internal body and external environment • animals may regulate some conditions and conform to others homeostasis • maintaining internal environment at relatively constant conditions • temperature, pH, blood glucose, salinity, pressure, water levels • important for: ○ enzyme function ○ organ function ○ metabolic efficiency ○ structural integrity of cells, proteins § optimal performance • homeostasis is regulated by negative feedback feedback • negative: ○ reduces the change or output ○ reduced reaction to bring the system back to a stable state ○ more common; homeostasis • positive: ○ increases the change or output • negative: ○ reduces the change or output ○ reduced reaction to bring the system back to a stable state ○ more common; homeostasis • positive: ○ increases the change or output ○ amplified result to achieve the goal more quickly ○ ex. childbirth an organism has a relatively constant internal temperature during the day and night despite fluctuations of more than 20 °F between 12 pm and 12 am. when the seasons change, the organism experiences changes in its phenotype to help maintain its constant internal temperature. this organism is best described as: a. a regulator that acclimates to its environment ○ regulator: maintains its constant temperature ○ acclimation: seasonal phenotype b. a regulator that adapts to its environment c. a conformer that acclimates to its environment d. a conformer that adapts to its environment homeostasis is not static • circadian rhythm: daily cycle of physiological patterns ○ measurable and predictable variation ○ temperature, blood pressure, sleep/wake cycles ○ range is greater in conformers than in regulators ○ in various organisms, such as plants • can be maintained with minimal cues ○ present in plants as well ○ blind mole rats exhibit daily cycles ○ not the same for all organisms; requires evolution • disruptions cause problems: ○ jet lag (difference in timing of sunlight) ○ metabolism and weight gain ○ ex. obesity when rhythms are irregular metabolism • all chemical reactions within an organism ○ energy to fuel cellular processes, to build proteins, lipids, nucleic acids • metabolic rate → energy used over a period of time ○ measured as: § heat loss § oxygen used § calories consumed comparing basal metabolic rates (BMR) • in mammals, elephants use more total energy than shrews • per kg, small mammals have higher metabolic rates than larger animals metabolism and body size • larger animals have proportionally less surface area to support metabolic needs ○ as body size increases, total BMR increases due to increased overall consumption ○ mass-specific BMR decreases due to reduced surface area to volume ratio of tissues homeostasis: a. will fluctuate more in regulators than in conformers b. is primarily driven by positive feedback c. is important for enzyme function d. all of the above an animal's metabolic rate is related to a. its size b. its thermoregulator strategy c. its level of activity d. all of the above