BIOB34 Facilitated Study Groups PDF

Facilitated Study Groups (FSGs) for BIOB34 FSGs are weekly collaborative learning sessions for students who want to improve their understanding of challenging content in some courses at UTSC. In FSGs, you’ll discuss lecture material and important concepts, develop study strategies, and work...

Facilitated Study Groups (FSGs) for BIOB34 FSGs are weekly collaborative learning sessions for students who want to improve their understanding of challenging content in some courses at UTSC. In FSGs, you’ll discuss lecture material and important concepts, develop study strategies, and work through problems as a group to prepare for assignments and tests. FSGs will be led this semester by Shangzhi who excelled in the course previously and has been trained as a peer facilitator. Shangzhi is not a TA, and his role is not to teach or give you answers, but to help you strengthen your problem-solving ability so that you take charge of your learning. He will be contacting you through the UTSC FSG BIOB34 Quercus with a poll for when you would like sessions to be held  please complete this as soon as possible. 2 hours of sessions (both in-person and online) will be spread across the week to accommodate different schedules. Online sessions will also be recorded.  Module 1: What is an animal? What is animal physiology? What is animal “physiology”? An (incomplete) bit of history What is, and is not, an “animal” ≈ metazoan? Multicellular eukaryotes What do we study? Some unifying principles or themes: August Krogh Homeostasis, regulation Physical, chemical, electrical laws apply Size and temperature (affect everything) Evolutionary history (usually) matters Complexity and specialization What is animal physiology? The study of how animals work (function) Integrated function Protein structure 3 © K. Welch - Do not distribute  Aristotle emphasized relation of structure and function Greek classified organisms by “blood/no-blood” (384 – 322 BCE) speculated on body function considered father of physiology by some Greek physician and anatomist that applied physical laws to study of human function Erasistratus Greek first to suggest the heart was a pump (304 - ~250 BCE) named and identified function of cardiac tricuspid valve perhaps most accomplished physiologist of antiquity Galen first to use systematic, carefully-designed experiments to probe function Roman (129 - 216 CE) e.g. tied laryngeal nerve off in pig  no more squealing (nerves + larynx control voice) tied ureters off in apes  swelling of kidneys (kidneys involved in urine prod.) first to correctly describe pulmonary circulation, heart anatomy, coronary circulation Ibn al-Nafis first to confirm heart was a pump Syrian-Egyptian corrected some of Galen’s erroneous beliefs (1213 – 1288 CE) © K. Welch - Do not distribute 4  provided first complete description of circulatory system and properties of blood William Harvey English showed contractions of heart powered blood movement (1578 – 1657 CE) could not see capillaries, but speculated they must exist to complete “closed” circulatory system identified/named oxygen and hydrogen Antoine Lavoisier French discovered/described role of oxygen in combustion and aerobic metabolism (1743 – 1794 CE) first to suggest ‘blind’ experiments to ensure objectivity Claude Bernard discovered hemoglobin carries oxygen, nerves can regulate blood flow French (1813 – 1878) coined term “Milieu intérieur”: “stability of the internal environment (despite variable external environment) is the condition for the free and independent life” coined term “fight or flight response” Walter Cannon coined term “homeostasis” (expanding on Bernard’s work) American Dry Mouth Hypothesis: regulates thirst (1871 – 1945) © K. Welch - Do not distribute 5  1920 Nobel Prize: The August Krogh principle Physiology For every biological problem there is an animal on which it can or Medicine most conveniently be studied. Bar-headed goose: understanding adaptation to hypoxia David Keilen Fly: discovery of Cytochrome C and Giraffe: dynamic control of eventually “Krebs cycle” blood pressure © K. Welch - Do not distribute 6 Unifying themes Physiological processes governed by: Laws of chemistry, governed by: Laws of physics Mechanical theory is useful (help understand locomotion, cell motility, muscle function, skeletal dynamics) Laws of electricity apply (help understand excitable cells, membrane potential, neural circuits) © K. Welch - Do not distribute 7 What makes a metazoan (an animal)? Metazoans are eukaryotes Distinguished from prokaryotes © K. Welch - Do not distribute 8 What makes a metazoan (an animal)? Like all eukaryotes, metazoans are multicellular But not all eukaryotes are multicellular Multicellularity evolved several times independently © K. Welch - Do not distribute 9 What makes a metazoan (an animal)? Many potential selective https://doi.org/10.1016/j.mib.2022.102141 advantages to evolving multicellularity Let’s consider a few… © K. Welch - Do not distribute 10 Unifying themes: Homeostasis and regulation Exposure to a changing environment Food sources pH Temperature Oxygen Toxins/waste products Etc…. Single cell Direct interaction with environment © K. Welch - Do not distribute 11  Unifying themes: Rufous hummingbird (Selasphorus rufus) Homeostasis and regulation Multi-celled animals No/few cells directly exposed to environment “Environment” of cells is the interstitial fluid Defense (maintenance) of environment cells exist in = homeostasis Defended by: behaviour multiple tissue/organ systems © K. Welch - Do not distribute 12  Unifying Themes: Temperature, Body size More cells ≈ bigger size More control over internal environment Digesting large meals Control of metabolites, ions Over temperature Microbiome/symbionts(?) Size and temperature impact almost every physiological function © K. Welch - Do not distribute 13  Scaling relationships D C B A Dimension Unit (e.g.) Equation Value A Value B Value C Value D Length cm = length 1 cm 2 cm 3 cm 4 cm Surface area cm2 = 6 x length2 6 cm2 24 cm2 54 cm2 96 cm2 Volume cm3 = length3 1 cm3 8 cm3 27 cm3 64 cm3 © K. Welch - Do Not Distribute 14  Scaling relationships Some things are function of volume D total metabolic rate total heat production C B Some things are function of surface area A Respiration Absorption, expulsion © K. Welch - Do Not Distribute 15 Scaling relationships: A sphere Surface area- based, e.g. Heat loss to environment and volume-based, e.g. Internal heat production phenomena scale differently with size © K. Welch - Do Not Distribute 16 Unifying Themes: Temperature, Body size Consider body temperature (~37-40°C in mammals) Balance heat production (internal) and heat loss/gain (to/from external environment) Heat production scales ∝ 𝑉𝑜𝑙𝑢𝑚𝑒 Heat loss/gain scales ∝ 𝑉𝑜𝑙𝑢𝑚𝑒2/3 If resting animal cells (regardless of animal size) had a similar metabolic (i.e. heat production) rate, larger animals would have relatively less and less surface area for dissipating extra heat. © K. Welch - Do not distribute 17 A curious, colonial choanoflagellate Choanoflagellates are closest living relatives to metazoans Solitary or found in small, simple colonies Mono lake (Eastern Sierras of California, USA) Inhospitable, volcanic origins Hypersaline Alkaline Arsenic-rich Few species Brine shrimp Alkali flies Choanoflagellates Bacteria, algae, etc. © K. Welch - Do not distribute 18 A curious, colonial choanoflagellate Choanoflagellates are closest living relatives to metazoans Solitary or found in small, simple colonies Except for Barroeca monosierra Form unusually large colonies Compare B. monosierra (D), to closely related S. rosetta (E) © K. Welch - Do not distribute 19 A curious, colonial choanoflagellate Choanoflagellates are closest living relatives to metazoans Solitary or found in small, simple colonies Except for Barroeca monosierra Form unusually large colonies Compare B. monosierra (D), to closely related S. rosetta (E) Staining for DNA shows ~70 B. monosierra nuclei Bacterial DNA inside colony lumen! © K. Welch - Do not distribute 20 A curious, colonial choanoflagellate Staining for DNA shows ~70 B. monosierra nuclei Bacterial DNA inside colony lumen! Bacteria closely associated with colony and extracellular matrix in lumen Analogous to ‘microbiome’ found in most animals? Microbiome increasingly recognized as important to animal function (“physiology”)… © K. Welch - Do not distribute 21  Unifying Themes: Temperature, Body size More cells ≈ bigger size More control over internal environment Digesting large meals Control of metabolites, ions Over temperature Microbiome/symbionts(?) Size and temperature impact almost every physiological function © K. Welch - Do not distribute 22  Porifera (sponges) Homo sapiens Unifying Themes: Only a “few” cell types ~200 cell types Complexity and specialization No clearly organized tissues Highly distinct tissues and organ systems Multicellularity permits divisions/ distinctions Of cell types Of tissues Into organs and organ systems © K. Welch - Do not distribute 23  Physiological phenotype is product of genotype and environment Phenotype may change Phenotypic plasticity Ontogenetic changes In response to controlled variable Reversible: Acclimation/ (e.g. in lab) acclimatization In response to Daphnia natural variation © K. Welch - Do not distribute 24 What makes a All animal species can utilize metazoan (an animal)? sexual reproduction* Some animals can utilize asexual reproduction © K. Welch - Do not distribute 25 Sexual versus asexual Sexual reproduction enables reproduction greater genetic variation across generations This greater variation might make some individuals better suited if climate/ecosystem changes Remember, there is inter-individual i.e. Could enhance chance of genetic variability in both groups survival for species © K. Welch - Do not distribute 26  If sexual reproduction is so Genetic variability of sexually- great, why do some animals still produced offspring may mean use asexual reproduction? some in a “litter” possess better “adapted” genes than Prussian carp (Carassius gibelio) others in that litter # of “Fit” Genotypes Asexual reproduction makes (potentially many) clones of a individual If you happen to have the ‘good genes’, so do ALL of your offspring Generation Remember, there is inter-individual genetic variability in both groups © K. Welch - Do not distribute 27  Phenotype may change over generations Adaptation (e.g. the beaks of Darwin’s “Galapagos finches” Not all phenotypic traits are result of adaptation © K. Welch - Do not distribute 28  Why comparative physiology? How do animals deal with unique environments/challenges? How do animals exploit different niches? How do we make sense of species diversity? What are similarities/differences among species? How do evolutionary relationships shape the above? © K. Welch - Do not distribute 29 Why comparative physiology? Working to advance veterinary medicine Informing conservation of species and important ecosystem services they provide Working to advance human medicine Use of model organisms (Krogh principle) Commonalities of physiological design and function Novel medical insights/treatments/approaches © K. Welch - Do not distribute 30