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Obtaining Nutrients

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Obtaining Nutrients

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  1. Essential Knowledge: 2.A.3 Organisms must exchange matter with the environment to grow, reproduce, and maintain organization2.D.2 Homeostatic mechanisms reflect both common ancestry and divergence due to adaptation in different environments.4.A.4 Organisms exhibit complex Properties due to interactions between constituent parts4.B.2 Cooperative interactions within organisms promote efficiency in the use of energy and matter

  2. Obtaining Nutrients • What are the main feeding mechanisms of Animals? How do they ingest food? • Suspension feeders – aquatic animals that sift small food particles from water • Substrate feeders – animals that live in or on their food source • Fluid feeders – animals that suck nutrient-rich food from host • Bulk feeders – animals that eat relatively large pieces of food

  3. Obtaining Nutrients • What are the two modes of digestion? • Intracellular – hydrolysis of food inside vacuoles; vacuoles fuse with lysosomes where food can be broken down without damaging the cell. • Extracellular – breakdown of food in compartments that are continuous with the outside of the animal’s body • Gastrovascular cavity – one opening; food enters through the mouth and waste exit through the mouth • Complete digestive system / alimentary canal – two openings; food enters through the mouth and waste exits through the anus

  4. Tentacles Crop Gizzard Intestine Esophagus Pharynx Anus Gastrovascularcavity Food Mouth Mouth Typhlosole Lumen of intestine (a) Earthworm Foregut Midgut Hindgut Esophagus Rectum Anus Crop Mouth Gastric cecae (b) Grasshopper Stomach Gizzard Intestine Mouth Esophagus Epidermis Crop Anus Gastrodermis (c) Bird

  5. Tongue Sphincter Salivaryglands Oral cavity Mouth Salivary glands Pharynx Esophagus Esophagus Sphincter Liver Stomach Gall-bladder Stomach Ascendingportion oflarge intestine Gall-bladder Duodenum ofsmall intestine Smallintestine Pancreas Liver Smallintestine Smallintestine Pancreas Largeintestine Largeintestine Rectum Rectum Anus Anus Appendix A schematic diagram of thehuman digestive system Cecum

  6. Obtaining Nutrients • How do humans get nutrients from food to our cells? • Ingest food and begin to digest food in the mouth.Mostly mechanical breakdown; some enzymatic breakdown of starch. • Food/bolus passes from the mouth through the pharnx and esophagous to the stomach • What is the structure called that keeps food from passing into the trachea • Epiglottis closes over the glottis (the opening to the trachea)

  7. Obtaining Nutrients Food Epiglottisup • What do we call the rhythmic contractions of the esophagus that moves the bolus to the stomach? • perstalsis Tongue Epiglottisup Pharynx Esophagealsphinctercontracted Epiglottisdown Glottis Glottisdownand open Esophagealsphinctercontracted Larynx Trachea Esophagus Esophagealsphincterrelaxed Glottis upand closed Relaxedmuscles Tolungs Tostomach Contractedmuscles Relaxedmuscles Sphincterrelaxed Stomach

  8. Obtaining Nutrients • What do you call the muscles that regulate entrance and exit of the stomach? • Sphincter muscles • What are the primary functions of the stomach? • Continued Digestion – chemical and mechanical • Storage of food • Upon entry into the stomach ingested food is mixed with gastric juice. What is this mixture called? • chyme

  9. Obtaining Nutrients • What unique structures found within in the stomach allow it to do its job? • Highly folded interior surface of stomach – rugae • Gastric pits in the surface lead to gastric glands • Gastric glands have 3 types of specialized cells • Mucus cells – secrete mucus to protect lining of stomach • Parietal cells – secrete hydrochloric acid (HCl) • Chief cells – secrete pepsinogen which becomes pepsin in the presence of HCl – used to break down proteins

  10. Fig. 41-12 Esophagus Sphincter Stomach Sphincter 5 µm Small intestine Folds ofepithelialtissue Interior surfaceof stomach Epithelium 3 Pepsinogen and HClare secreted. 1 Pepsinogen Pepsin 2 HCl Gastric gland 2 HCl convertspepsinogen to pepsin. 1 3 Pepsin activatesmore pepsinogen. Mucus cells H+ Cl– Chief cells Chief cell Parietal cells Parietal cell

  11. Obtaining Nutrients • Where does most of the enzymatic break down of macromolecules from food occur? • Small intestine • Where does most of the absorption of nutrients take place? • Small intestine • How is the structure of the small intestine specialized for absorption? • Huge surface area created by finger-like projections called villi • Each epithelial cell of villi have microvilli that are exposed to the interior of the intestine

  12. Microvilli (brushborder) at apical(lumenal) surface Vein carrying bloodto hepatic portal vein Lumen Bloodcapillaries Epithelialcells Basal surface Muscle layers Largecircularfolds Epithelial cells Villi Lacteal Key Lymphvessel Nutrientabsorption Villi Intestinal wall

  13. Obtaining Nutrients • How are sugars such as glucose and fructose absorbed? • The simple sugar fructose moves via facilitated diffusion down their concentration gradient from the lumen of the small intestine into epithelial cells. • Fructose continues to move from high to low concentration until they enter microscopic blood vessels in the villi • Glucose and other nutrients are pumped against concentration gradients by the epithelial cells – to allow for maximum uptake of nutrients into blood vessels

  14. Obtaining Nutrients • What is the energy content of food measured in? • Kilocalories = Calories on a food label • What do we call the number of Calories a resting animal requires to fuel processes essential to life? • Basal Metabolic Rate (BMR) – the amount of energy we “burn” lying motionless • 1,300 to 1,500 for females • 1,600 to 1,800 for males • What happens when we take in too many Calories? • Excess energy stored as glycogen or fat

  15. Eliminating Wastes • What are two roles of the large intestine? • Absorption of water by osmosis • Elimination of digestive waste – feces • How do the bacteria that reside in our large intestine help us? • They produce vitamins, such as biotin, vit K and several B vitamins, including folic acid. • What is the terminal portion of the large intestine called? • rectum

  16. Eliminating Wastes • What are the main processing centers for liquid waste? • Kidneys Renal medulla Posterior vena cava Renal cortex Renal artery and vein Kidney Renal pelvis Aorta Ureter Urinary bladder Ureter Urethra Section of kidney from a rat (a) Excretory organs and major associated blood vessels (b) Kidney structure 4 mm

  17. Eliminating Wastes Afferent arteriole from renal artery Glomerulus Juxtamedullary nephron Cortical nephron Bowman’s capsule 10 µm SEM Proximal tubule • How is the structure of a kidney specialized for excretion? • Each kidney contains about a million nephrons Peritubular capillaries Renal cortex Efferent arteriole from glomerulus Collecting duct Distal tubule Branch of renal vein Renal medulla Collecting duct Descending limb To renal pelvis Loop of Henle Ascending limb Vasa recta (c) Nephron types (d) Filtrate and blood flow

  18. Eliminating Wastes • How do Nephronselinimate waste? • Filtration: Fluid called filtrate is forced out of the glomeruls (a ball of capillaries) and into the Bowman’s capsule (the cup-shaped swelling of a nephron) • Reabsorption and Secretion: As the filtrate travels through the various sections of the neprhon - the prximal tubule, descending limb of the loop of Henle, the ascending limb of the loop of Henle, and the distal tublule - ions and nutrients are reabsorbed and waste is secreted • Excretion: waste travels from nephron to collecting duct to the renal pelvis to the ureter to the urinary bladder and out the urethra

  19. Eliminating Wastes • What happens at the Bowman’s Capsule? • Filtrate from the blood enters the nephron • What happens at the proximal tubule? • Drugs, poisons, and H+ are excreted • Nutrients, NaCl, Water, HCO3- are reabsorbed • What happens in the Loop of Henle? • Water and NaCl are reabsorbed • What happens in the distal tubule? • NaCl, Water, and HCO3- are reabsorbed • K+ and H+ are secreted • What happens in the collecting duct? • NaCl, Urea and water are reabsorbed

  20. Eliminating Wastes • How does the solute concentration of the medulla and cortex maximize reabsorption? • The solute concentration is lowest in cortex of the kidney and highest in the medulla

  21. Proximal tubule Distal tubule NaCl Nutrients H2O HCO3– H2O K+ HCO3– NaCl H+ H+ NH3 K+ Filtrate CORTEX Loop of Henle NaCl H2O OUTER MEDULLA NaCl NaCl Collecting duct Key Urea NaCl Active transport H2O INNER MEDULLA Passive transport

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