Nutrition in Animals - BIOL 206 Lecture Slides PDF

Nutrition in Animals BIOL 206 Dr. Jason Lambert Office: BI 365; F 2:00pm – 4:00pm Email: [email protected] Learning Objectives Identify and Describe the nutrients that are “essential” to the structure and function of mult...

Nutrition in Animals BIOL 206 Dr. Jason Lambert Office: BI 365; F 2:00pm – 4:00pm Email: [email protected] Learning Objectives Identify and Describe the nutrients that are “essential” to the structure and function of multicellular organisms. Describe how multicellular organisms acquire nutrients. Explain from where nutrients are absorbed and how they are processed. Explain examples of nutritive strategies, including the role of symbiotic relationships. Outline Contrast with Plants Macromolecules Energy Obtaining energy & essential nutrients Heterotrophy Nutritive strategies Digestive tracts Ingestion Digestion & Absorption Symbiosis Nutritional Control Hormones Homeostasis Animal Nutrition: Contrasted with Plants While most plants are autotrophs, all animals are heterotrophs Depend on nutrients synthesized by autotrophs Animal Nutrition: Key Terms Food – material that contains nutrients Nutrient – a substance that provides organisms with energy and raw materials Carbohydrates These 3 = major macromolecules used Fats as carbon-containing building blocks Proteins Energy – capacity to do work Motion (of bodies or molecules) Ability to maintain concentration, electrochemical, or thermal gradients Measuring Energy Heat energy 1 calorie is the amount of heat needed to raise 1 gram of water 1°C 1 kilocalorie (kcal) = 1,000 calories NOTE: the “Calorie” (Cal) on nutrition labels is actually a kcal! Energy in Macromolecules Energy in Macromolecules Energy storage Carbohydrates – stored in liver and muscle cells as glycogen; typically, enough is stored for about 1 day’s worth of energy needs Fat – higher density energy storage used for long term energy storage Proteins – not used as a specific store of energy, but our bodies are capable of breaking down proteins for an energy source – it’s the last resort. Macromolecules: The acetyl group One of the major organic molecules animals require are compounds which contain acetyl groups, because they are the basis for carbon skeletons. Obtaining Energy & Essential Nutrients Four classes of essential nutrients Essential amino acids Essential fatty acids Vitamins Minerals Obtaining Energy & Essential Nutrients Four classes of essential nutrients Essential amino acids Essential fatty acids Two essential fatty acids in humans Vitamins Linoleic acid (an omega-6) Minerals α-linolenic acid (an omega-3) Obtaining Energy & Essential Nutrients Four classes of essential nutrients Essential amino acids Vitamins are organic compounds we need to obtain Essential fatty acids from our diet for normal function of our metabolism. Vitamins Minerals Obtaining Energy & Essential Nutrients Four classes of essential nutrients Essential amino acids Minerals are inorganic elements (ions/atoms) we need to obtain from our diet for normal function of our metabolism. Essential fatty acids Vitamins Minerals Obtaining Energy & Essential Nutrients Classifications of Heterotrophs based on feeding strategies Detritivores Relationships between 4 major classes of feeding strategies: Feed on dead organic matter Scavengers Saprotroph decomposers Predators Feed on living organisms Predation = killing (usually targeting animals) Parasitism = not killing Herbivory = targeting plants Diagram by Ian Alexander Obtaining Energy & Essential Nutrients Discuss the following multiple-choice question with a neighbor: To maintain adequate nutrition, animals must have access to sources of certain amino acids. An amino acid that is NOT considered “essential” would be best described as one that... a. can be made by the animals’ body from other substances. b. is not used by the animal to make proteins. c. must be ingested in the diet. d. is not readily absorbed by the gastrointestinal tract. Nutritive Strategies Digestive Systems Animal processes for getting energy and raw materials are interdependent and coordinated across multiple organs: 1. Ingestion Overview 2. 3. Digestion Absorption 3 4 4. Elimination 2 1 Animal digestive functions are interdependent and occur simultaneously, usually coordinated across multiple organs. Slide 15 Lecture 4 Nutritive Strategies Ingestion – the act of acquiring food and bringing it into the animal body Suspension feeder Deposit feeders Fluid feeders Mass feeders Nutritive Strategies Ingestion Mouth parts are specialized adaptations for maximizing food acquisition Primarily grabbing and biting off chunks of prey, but may also facilitate pre-digestion breakdown of food into smaller particles (i.e., chewing). Pharyngeal jaws of rift lake cichlids Nutritive Strategies Ingestion Mouth parts are specialized adaptations for maximizing food acquisition Without chewing, animals swallow their prey whole and another adaptation (gizzard) in the digestive tract must mechanically process the chunks of food so they may be digested. Nutritive Strategies Digestive Tracts – structures for digestion and absorption 2 types: Gastrovascular cavity – only one opening also called an “incomplete digestive tract” ingestion and elimination occur at same opening Tubular guts – opening at each end of the animal “complete digestive tract” ingestion occurs at mouth elimination occurs at anus Nutritive Strategies Digestive Tracts You’ve already seen an example of an organism with a gastrovascular cavity digestive tract... Dugesia flatworm Nutritive Strategies Digestive Tracts – Tubular gut What are the advantages of a tubular gut over a gastrovascular cavity? Nutritive Strategies Digestive Tracts – Human example Overview: Mouth – mechanical breakdown; enzymes in saliva begin chemical breakdown of carbs and lipids Stomach – mechanical breakdown cont.; acidic environment; chemical digestion of proteins begins Small intestine – chemical digestion of carb/lipid/protein; absorption of breakdown products, water, vitamins, ions Large intestine – more water absorbed; remaining material prepared for excretion. Nutritive Strategies Human stomach # 𝐂𝐎𝟐 + 𝐇𝟐 𝐎 ↔ 𝐇𝟐 𝐂𝐎𝟑 ↔ 𝐇𝐂𝐎𝟑 + 𝐇$ Nutritive Strategies Human small intestine Site of most digestion and absorption Nutritive Strategies Human small intestine Site of most digestion and absorption What is the function of folds, villi, and microvilli? What’s the difference between villi and microvilli? Nutritive Strategies Human small intestine Breakdown of proteins, carbs, and fats using enzymes produced by the liver and pancreas Liver produces bile which helps emulsify fat for digestion Pancreas produces digestive amylases, lipases, and proteases + bicarbonate (HCO3-) Emulsification Vital process for digestion of fats! Emulsification Vital process for digestion of fats! Nutritive Strategies Human small intestine Breakdown of proteins, carbs, and fats using enzymes produced by the liver and pancreas Liver produces bile which helps emulsify fat for digestion Pancreas produces digestive amylases, lipases, and proteases + bicarbonate (HCO3-) Nutritive Strategies Absorption Uptake of simple sugars, short peptides, and amino acids by: Facilitated diffusion Co-transport Selective Active transport Uptake of fatty acids and monoglycerides Simple diffusion WHY? Nutritive Strategies Absorption Import of glucose when concentration gradient favors movement into the cell Facilitated diffusion though carrier proteins No energy input required Selective – only lets in what fits the binding pocket! Outside cell Glucose GLUT-1 Inside cell 1. Unbound 2. Glucose 3. Conformational 4. Release protein binding change Nutritive Strategies Absorption Import of glucose when concentration gradient does not favor movement into the cell Co-transport and secondary active transport  Active Transport Energy for active transport can be extracted by the transporter (primary active transport) OR Energy for active transport can be harnessed from an existing electrochemical gradient (secondary active transport). Slide from BIOL 205 Lecture 7 – Membrane Transport  Nutritive Strategies Symbiosis The microbiome of your gut assists you greatly in breaking down food. Anaerobic bacteria break down complex carbs in the fiber we ingest Produce many metabolites which we secondarily consume from them: Short chain fatty acids (SCFAs) like acetate (cholesterol metabolism and lipid production) and propionate (regulates sugar conversion and storage in the liver and the sensation of satiety). Vitamin K – important for blood clotting and bone development Vitamin K1 structure by Tony27587 Nutritive Strategies Symbiosis Ruminants Herbivores cannot break down cellulose, and yet, that is primarily what they ingest... Their “food” is more accurately the microbes they grow in their rumen and reticulum! A ruminant derives 100+ grams of protein per day from digestion of endosymbionts! Nutritive Strategies Symbiosis Elysia chlorotica (emerald elysia) A member of the “sap sucking sea slugs” which feed on algae It retains functional chloroplasts after digesting the algae for food and uses them to perform photosynthesis! Maybe a little less than mutualistic... Elysia supports the survival of the chloroplasts through at least one photosystem gene acquired through horizontal gene transfer 500 µm Nutritional Control Stimulus Hormones are used to Endocrine cell coordinate whole body Feedback inhibition responses to a stimulus. Hormone The signal is distributed through the bloodstream Effector Each effector cell cell responds, no matter how distantly spaced. Response We will talk more about these mechanisms in our Sensing theme... Nutritional Control Example: Stomach and Intestine coordinate their activity using hormones. Stomach produces gastrin When food is present gastrin stimulates release of HCl and pepsin Low pH negatively feeds back on gastrin release Increased activity in the stomach leads to increased delivery of chyme to the small intestine Intestine produces secretin & cholecystokinin Secretin and cholecystokinin both signal to the stomach to slow down Secretin stimulates release of bicarbonate from the pancreas Cholecystokinin stimulates release of bile from the gallbladder and digestive enzymes from pancreas Nutritional Control Homeostasis of glucose (cellular fuel) Glucose Glycogen Insulin stimulates cells in liver and muscle to synthesize glycogen Pancreas secretes Glycogen: energy storage INSULIN polysaccharide (lots of glucose monomers chained together) If glucose level is too high Glucose stored in liver and muscles Homeostasis (normal glucose level falls Regulated by hormones synthesized If glucose level in blood) Glucose level is too low level rises in the pancreas Insulin – promotes conversion of glucose Pancreas secretes to glycogen GLUCAGON Glucagon stimulates cells in Glucagon – stimulates the liver to break liver to catabolize glycogen down glycogen and release glucose into the bloodstream Glycogen Glucose Nutritional Control Homeostasis of glucose (cellular fuel) Blood sugar levels have a set point of ~100 mg/dL Proteins in β-cells of the pancreas act as sensors, integrators, and insulin acts as the effector. β-cell diagram from Röder et al. (2016)  Nutritional Control Homeostasis of glucose (cellular fuel) The insulin receptor on liver cells (and other cells) is a transmembrane signaling protein called a Receptor Tyrosine Kinase (RTK) 824 Chapter 15: Cell Signaling Insulin binding changes the RTK’s shape, which changes its behavior. extracellular Figure signal molecule comple phosphoinositide plasma interac docking sites membrane based o an enzy tyrosine P P P P CYTOSOL the acti P P itself on PH PH phosph protein P PTB Sos (IRS1) v SH3 domain activated phosph receptor P P SH2 Grb2 (adaptor protein) the plas recepto P SH3 and one P the SH2 Grb2. N scaffold protein domain IRS1 (docking protein) a protei Cryo-EM structures and structure diagrams from Gutmann et al. (2018) downst