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Respiratory and Digestive Systems in Biology

Explore the functions and mechanisms of the respiratory and digestive systems in animals, focusing on gas exchange and nutrient absorption processes. Learn about countercurrent exchange, tracheae in insects, human lungs, and the respiratory system. Understand the importance of ventilation mechanisms in different animals and the osmoregulation processes in aquatic vertebrates.

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Respiratory and Digestive Systems in Biology

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  1. DOR: Digestive System • ___________ is the process of smooth esophageal muscles contracting to move food down into the stomach. • Name the acid located in the stomach. • __________ are located in the small intestine and contain capillaries for nutrient absorption. • What is the main function of the large intestine? • Name the accessory organ that stores bile.

  2. Respiratory System Chapter 35

  3. Why do we need respiration???

  4. Gas-exchange, simple animals • Diffusion • Presence of capillaries help • Animal’s surface becomes important, huge surface area to allow for gas exchange • Oxygen, transport to mitochondria

  5. Gas exchange, aquatic animals • More energy spent with respiration • Possess large surface area (ex. Cnidarians, flatworms) • Invertebrates/vertebrates—gills • contain vascular/blood system • Divided growths from surface/pharynx

  6. Gills • Molluscas: gills located in mantle where water goes through • Fish—mouth and opercula (gill covers) put in a combined effort • Countercurrent exchange utilized—blood always surrounded by water with high oxygen content, prevents equilibrium

  7. Countercurrent Exchange- blood & water flow in opposite directions

  8. Countercurrent Exchange (Aquatic Animals) • Countercurrent exchange allows for the efficient transfer of oxygen to the blood • As blood flows through the capillary, it becomes more and more loaded with oxygen • Steep concentration gradient allows for efficient uptake of oxygen

  9. Insect Tracheae • Open circulation system so this transport not well-developed • Tracheae • Air tubes throughout insect, transport O2 to cells • Branching systems (small tubes—tracheoles) close to cells to ensure O2 transport/CO2 removal • Air sacs • Located at wings, legs, abdomen • Help circulate air and pass through air tubes **Insects can contract and relax air sacs at muscles to circulate air---similar to human lungs

  10. Human Lungs • Located within thoracic cavity • Air filtered as it moves into lungs • Hairs/cilia line respiratory tract to “sweep” debris out and mucus traps particles • Branching: Trachea---bronchi----bronchioles----alveoli • Alveoli— • take up most of the surface area, • surrounded by capillaries to facilitate gas exchange between lungs and blood

  11. Human Respiratory System • Air enters the lungs by a system of branching ducts • Nostrils • Pharynx • Larynx • Trachea (w/ cilia) • 2 bronchi • Bronchioles • Alveoli

  12. Human Respiratory System

  13. Mechanism of Breathing • Negative pressure— • Used to get air in lungs • Positive pressure forces air out • Ex. Birds, mammals, reptiles • Positive pressure— • Air is forced into the lungs • Ex. Amphibians

  14. Mechanism (cont.) • Inspiration— • Air movement INTO lungs • Expiration— • Air movement OUT of the lungs • Other structures • Diaphragm—horizontal muscle separating thoracic cavity and abdominal cavity • Intercostal muscles—aids in inspiration, muscles along the rib cage.

  15. Inspiration • Diaphragm moves down • Rib cage moves • Thoracic cavity expands to allow air to move in • Pressure decreased in lungs, air flows in. • Active phase, intercostal muscles contract

  16. Inspiration

  17. Expiration • Diaphragm relaxation, returns to location • Passive phase, no contractions • Air moves OUT of the lungs--- pressure increases to force air out !

  18. Expiration

  19. Tidal ventilation mechanism • Most vertebrates, not birds • Air passes through the same path going in OR out • Some air does not completely leave the lungs, air mixing occurs—water conservation

  20. What about birds? • One-way ventilation mechanism • Only with birds • Air coming in goes FIRST to posterior air sacs • Then lungs to anterior air sacs • No air mixing occurs, better gas exchange efficiency.

  21. Respiratory Gas Exchange • Mainly by diffusion • How O2 gets in/CO2 gets out of tissues and lungs • Partial pressure— • Amount of pressure given off by gases • PO2 , PCO2 • Pressure different causes diffusion to occur • Alveoli– HIGH PO2 , LOW PCO2 • Tissues—LOW PO2, HIGH PCO2

  22. Oxygen Transport • 1) External Respiration • CO2 enters lungs from tissues via hemoglobin, mostly bicarbonate (HCO3-) • Involves carbonic anhydrase • O2 combines with hemoglobin via iron • 2) Internal Respiration • PO2 in tissues < blood PO2 • Oxygen leaves hemoglobin, moves into tissues • PCO2 in tissues > blood PCO2, movies into blood

  23. Excretory/Urinary System

  24. Osmoregulation Overview • Water and salt balance in body • Doubles as excretory system

  25. Osmoregulation (cont.) • 1) Aquatic Vertebrates • Main function of kidneys: urine production • Cartilaginous fish: excrete urea, plasma isotonic in seawater • Marine bony fish: potential for dehydration due to hypertonic environment, always “drinking” water • Freshwater bony fish: potential to gain TOO much water, make “dilute” urine, no drinking of water

  26. Osmoregulation (cont.) • 2) Terrestrial Vertebrates • Specialized glands to get rid of salt • Ex. Sea birds • Kidneys produce concentrated urine • Prevents dehydration and enhances water conservation • Ex. Kangaroo rat

  27. Excretion • Metabolic waste removal • Many molecules broken down into nitrogen-containing compounds • Toxic in excess so removal necessary • 3 methods of removal • 1) Ammonia • 2) Urea • 3) Uric Acid

  28. 1. Ammonia Excretion • Amino groups formed from immediate removal from amino acids • Easily eliminated, no energy needed • Potentially toxic, requires lots of water available • Ex. Fish, animals with gills in aquatic environment.

  29. 2. Urea Excretion • Moderately toxic, can be eliminated as a slightly toxic substance • Helps with water conservation • Production via liver, does require energy • Ex. Sharks, amphibians, mammals

  30. 3. Uric Acid • Very energy intensive • Requires a series of reactions to be produced • Does not dissolve in water, great for water conservation • Least toxic • Protects reptilian and bird eggs from toxic nitrogen excess in developing eggs • Ex. Insects, reptiles, birds, humans occasionally.

  31. Invertebrate Excretion • 1) Flatworms • Excretory tubules that secrete wastes through pores • Removes water and waste • 2) Earthworms • Nephridia located at every segment and reabsorbs nutrients • Urine eliminated via pores • 3) Insects • Malpighian tubules • Uric acid moves from hemolymph to tubules • Water moves down salt gradient • Reabsorption occurs at rectum but uric acid eliminated • Aquatic---waste removal through gills

  32. Homework • Read Chapter 35, pp. 681-684 • Pp. 678-679, “Testing Yourself” #1-13

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