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Homeostasis in mammals

Homeostasis in mammals. The body’s way of achieving a constant/stable internal environment Changes of external or internal environment stimulate homeostatic responses, feedback system Thermostat example. All body systems play a vital role in achieving this homeostasis. Digestive System.

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Homeostasis in mammals

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  1. Homeostasis in mammals The body’s way of achieving a constant/stable internal environment • Changes of external or internal environment stimulate homeostatic responses, feedback system • Thermostat example. • All body systems play a vital role in achieving this homeostasis.

  2. Digestive System

  3. Function Of Digestion Digestion contributes to animals homeostasis by providing the bodies cells with nutrients needed to sustain life. • Ingests food • Breaks down (B) done two ways • Absorption (A) of these molecules to circulatory system • Elimination (E) of nondigested materials.

  4. Mammalian Digestive System Breakdown is done by 2 mechanisms: • Mechanical: increase SA:Vol • Chemical: polymers into monomers(small enough to be transported across plasma membrane). The beginning: 1)Mouth(B): Salivary glands = Salivary Amylase; Enzyme that chemically breaks down polysaccharides into monosaccharides - Food  Bolus

  5. Mammalian Teeth(B) Incisors: Chisel-like; in front. fxn = cutting, gnawing, grooming Canines: Pointy, just lateral to incisors fxn = piercing, gripping, tearing. Molars: Flat and large SA; dorsally to canines fxn = crushing, grinding

  6. 2)Pharynx & Esophagus (B) • Pharynx = Where digestive and respiratory systems separate. Epiglottis covers opening to trachea. • Esophagus = Tube that takes bolus to stomach; done by peristalsis. (Sal. Amylase contd.)

  7. Peristalsis

  8. 3) Stomach (B) Deep folds = increase surface area for more efficient breakdown. 2 smooth muscles seal bolus in sac (cardiac & pyloric sphincters) Gastric juice: • Pepsin = Hydrolytic enzyme(?); breaks down proteins to amino acids • HCL = pH of 2 kills microorganisms - Shuts down Salivary Amylase Bolus  Chyme

  9. 4) Small Intestine (B&A): 3m long, 3 regions; duodenum, jejunum, & ileum 1)Duodenum (B&A): Accessory organs help complete the breakdown of proteins and carbohydrates & begin fat digestion. • Liver = produces Bile: Breaks down Lipids; Stored in gall bladder • Pancreas: sodium bicarbonate = High pH (why?) Pancreatic Amalyse = Starch  glucose Trypsin = Protein  Amino acids Lipase = also breaks down Lipids

  10. 2)Jejunum(B & A) : intestinal enzymes • Peptidase: proteins  Amino acids

  11. Villi: Folded furrows that increase S.A./ Vol. ratio. Found along entire sm. intest.(if stretched S. I. = 500-600m long) Small monomers absorbed by villi and microvilli. Each villus contains capillaries used to transport those nutrients to rest of body. Active and Facilitated transport involved. C) Ileum (A): Finishes absorption of monomers

  12. Small Intestine Histology

  13. 5) Large Intestine (E) 3 regions Cecum: Breakdown of cellulose (symbiosis; mutualism) Colon: Elimination of water from chyme  feces Rectum: storage for removal from body.

  14. Digestive Homeostasis: Regulation of Blood sugar by the pancreatic hormones

  15. Nutrition and Health Consequences

  16. The End

  17. Digestive Dissection Draw and identify the location and function of the following digestive organs: • Mandibular gland • Esophagus • Stomach • Cardiac Sphincter • Pyloric Sphincter • Small intestine • Duodenum • Jejunum • Ileum • 5. Large intestine • Ileuo-caecal sphincter • Caecum • Colon • Rectum • Accessory organs: • Liver • Pancreas

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