life 103 week 5 class notes
life 103 week 5 class notes life 103
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This 8 page Class Notes was uploaded by Devrrae Russell on Monday September 26, 2016. The Class Notes belongs to life 103 at Colorado State University taught by Heather Baker Blackburn in Fall 2016. Since its upload, it has received 7 views.
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Date Created: 09/26/16
September 19, 2016 Animal form and function; the interaction of the body with the external environment Concepts 40. 1-3 Organisms have to exchange energy and materials with the environment ● Food, waste, gases, energy ● Materials must be dissolved in aqueous solution to move across a membrane ● Single cellular and diploblastic organism use diffusion ● Flatworms can get most of their needs from diffusion ; the rest is diffused from the gastrovascular cavity High surface area to volume ration ● Pro ○ Good diffusion ○ Less needed for efficient distribution systems ● Cons ○ More difficult to control gain and loss ○ Limits complexities More complex animals ● Advantages for function and versatility in different conditions ● Need more than body surface area for contact with environment ○ Lungs ● Exchange surfaces are highly branched or folded, often internal ● Cells have to be surrounded by fluid Internal exchange surfaces allow regulation of water loss ● Waterproof body covering reduces loss to evaporation ● Control of exposure to the environment ● Humid enclosure decrease evaporation rate Strategies for dealing with variations in the external environments ● Regulators ○ Limits internal change with internal mechanisms ● Conformers ○ Allow internal conditions change with external environment Homeostasis is a relatively constant set of internal conditions ● Animals may maintain homeostasis in ○ Body temp ○ Blood ph ○ Concentration of glucose and other solutes ■ Bass ● Temp conformer ● Regulates internal solute concentrations Animals use feedback loops to maintain variables near a set point or normal range ● Thermostat example ● Sensors detects stimulus ● Sensor signals control center ● Control center generates signal that triggers response ● Negative feedback reduces stimulus ○ Reduces stimulus ○ Response stops when the variable is back in the normal range ○ Not instant ● Positive feedback amplifies the stimulus ○ Child birth ■ Pressure near the cervix stimulates uterine contraction ■ Contraction increase pressure ■ Baby pops out ● Regulated changes in the normal ranges for homeostasis ○ Hormones shift at developmental stages ○ Cycles in metabolism ■ Circadian rhythms - 24 hrs ○ Responses to environment ■ Acclimatization ● Gradual adjustment to environment Homeostatic processes for thermo regulation involve form function and behavior ● Strategies for thermoregulation ○ Endotherms ■ Use metabolism to create heat ■ Eat more ○ Ectotherms ■ Warmed by environment ■ Eat less ○ Poikilothermic ■ Body temp varies widely ○ Homeothermic ■ Body temperature remain relatively constant ■ Lots of poikilotherms are ectothermic ● Exceptions ● Regulating heat loss ○ Radiation ■ Emissions from sun rays (emag waves) ○ Evaporation ○ Convection ○ Conduction ○ Insulation ○ Fur ○ Fat ○ Feature ○ blubber September 21, 2016 Animal form and function; the interaction of the body with the external environment Concepts 40.1-3 Circulatory adaptations affect heat flow ● Peripheral vasodilation ○ Increases blood flow to the skin ○ Increases heat loss by radiation ● Peripheral vasoconstriction ○ Reduces heat transfer and or loss ● Dive response in mammals reduces heat loss ○ Infants and water mammals hold their breath on contact with cold water ● Heat diverted to the core; smaller temp gradient th the environment minimizes heat loss ■ Countercurrent exchange ○ Duck feet ○ Flippers of marine mammals Evaporative heat loss can be used for cooling ● Respiratory surfaces and skin ● Bathing, sweating, panting; gasping in reptiles Behavioral mechanisms for regulating heat flow ● Orient or move toward or away from a warm surface or the sun ● Basking in the sun Animal nutrition Concept 41 Diet must supply: ● Chemical energy for cellular processes ● Organic building blocks for macromolecules ● Essential nutrients ○ Must be obtained from their diet ○ 4 classes ■ Essential amino acids ● 20 amino acids total ● Most animals can produce approximately ½ ● Humans have 9 amino acids ● Animal products vs vegetables ■ Essential fatty acids ● Only 2 in humans ○ Linoleic acid - omega 6 ○ Alpha linolenic acid - omega 3 ● Precursors to others that we can make with limited efficiency ■ Vitamins ● Organic molecules ● 13 are essential for humans ○ Fat soluble - A D E K ○ Water soluble - B C ● Toxic in large amounts ■ Minerals ● Simple inorganic nutrients ● Ingestion of large amounts can upset the homeostatic balance ● Animals may eat snail shells, salt lick, licking rocks, etc… Deficiencies in essential nutrients ● Can cause deformities, disease, and even death ● “ golden rice” with beta carotene, converted to vitamin A in the body Stages of food processing 1. Ingestion a. Taking food into the body 2. Digestion a. Breaking food down into pieces and molecules small enough to absorb i. Mechanical digestion 1. chewing ii. Chemical digestion 1. Into small molecules that can pass through membranes 2. Enzymatic hydrolysis a. Break down with the aid of water b. Intracellular digestion i. Phagocytosis ii. Food vacuoles, containing food, fuse with lysosomes containing enzymes iii. Sponges, single cellular organisms c. Extracellular digestion i. breakdown of food particles outside of cells ii. Animals with simple body plans 1. Gastrovascular cavity iii. More complex animals 1. Digestive tube with 2 openings 2. Alimentary canal 3. Can be specialized with regions to carry out digestion and absorption September 23, 2016 Mammalian digestive system consists of the alimentary canal and accessory glands ● Accessory glands: ○ Salivary glands ○ Pancreas ○ Liver ○ Gallbladder ● Food pushed by peristalsis and regulated by sphincters ● Heartburn? First steps 1. Chewing 2. Salivary glands 3. Saliva a. Amylase i. Enzyme breaks down starch and glycogen b. Mucous i. Slipperry c. pH buffer d. Antimicrobial agents 4. Bolus forms a. Pushed into the pharynx by the tongue 5. Pharynx opens into trachea and esophagus a. During swallowing the epiglottis flips down to seal trachea 6. Peristalsis pushes it down to the stomach 7. Chemical digestion a. About 1 L volume at rest; can stretch to accommodate 2 to 3 L b. Secrets gastric juice into the lumen and churns to mix it with food i. Forms chyme c. Gastric juice i. pH about 2 ii. HCl iii. Pepsin - protease break down of proteins into smaller polypeptides 1. Pepsin and HCl are not active till it reach the stomach a. Parietal cells secrete H+ and Cl- separately b. Chief cells secrete pepsinogen c. HCl and pepsin activate pepsinogen to pepsin 8. Moves down to the the duodenum 9. Moves to small intestine a. > 20 feet long in humans b. Most digestion occurs here c. Pancreatic secretion (liver gallbladder and pancreas) i. Lipases - Fats ii. Nucleases - DNA/RNA iii. Proteases - Proteins iv. Amylases - Polysaccharides d. Villi and microvilli - surface area ~ 200-300 m^2 e. Active or passive transport of amino acids vitamins, monosaccharides, etc… into epithelial cells f. Diffuse into blood i. Hepatic portal vein to the liver 10. Moves to large intestine a. Colon leads to rectum and anus b. Cecum is important for fermentation c. Colon reabsorbs remaining water leaves