1 / 39

Chapter 42

Chapter 42. Circulation & Gas Exchange. Dzmitry Malyshka. Tal Eidenzon. Circulation in Animals. The need for a circulatory system arose with the increased size of the animal. That is due to the need to transport nutrients across the whole body.

avital
Download Presentation

Chapter 42

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 42 Circulation & Gas Exchange DzmitryMalyshka • Tal Eidenzon

  2. Circulation in Animals • The need for a circulatory system arose with the increased size of the animal. That is due to the need to transport nutrients across the whole body. • Smaller animals do not have a circulatory system and thus depend on diffusion. • Some small animals have a gastrovascular cavity which can both digest food and transport nutrients.

  3. Open Circulatory System • In this system, blood is pumped by the heart, but not in a closed circuit. • Instead, blood leaves the heart and then bathes the organs, only to be picked up by other vessels later on and returned to the heart. • Most of the time it does not transport oxygen, and the “blood” is actually hemolymph, which is the mixture of blood and the interstitial fluid that bathes tissues of organs. • This system is seen in arthropods and most mollusks.

  4. Closed Circulatory System • Present in earthworms, squids, octopuses, and vertebrates. • In this system, blood is confined to vessels, and has no mixing with the interstitial fluid. • In here, a heart or multiple hearts pump the blood through vessels that continue branching out into smaller vessels where the transported materials later diffuse into the interstitial fluid surrounding the tissue.

  5. Cardiovascular System • All vertebrates have a cardiovascular system, which is a closed circulatory system that transports nutrients across the body. • Composed of: • Arteries (carry blood away from the heart). • Veins (carry blood towards the heart). • Capillaries (“bridge” from arteries into veins). • Heart (the pump). • Fish, Amphibians, Reptiles, and Mammals all have a different cardiovascular system.

  6. Fish Cardiovascular System • Fish have a two-chambered heart and only one circuit of circulation. • Blood flows from the heart to the gills, where it gets oxygenated. • From the gills, blood flows directly to all the organs where it gets deoxygenated before going back to the heart.

  7. Amphibian Cardiovascular System • Amphibians have a three-chambered heart and two circuits of vessels. • There is some mixing of the blood in the middle chamber of the heart (the ventricle).

  8. Reptilian Cardiovascular System • Reptiles have a three-chambered heart and two circuits. • They have two aortas which ultimately transport blood to the tissues in the systemic circuit. • There is mixing of the blood, but no as much as in amphibians because the ventricle is partially seperated.

  9. Mammal & Bird Circulatory System • Birds and mammals have a four-chambered heart. • This setup allows for no mixing to occur. • There are also two circuits.

  10. Circuits of the Cardiovascular System • Fish have a single circuit, and that doesn’t allow fish to have a fast metabolism due to the slow movement of blood. The fact that blood slows down greatly after passing through the two sets of capillaries accounts for the slow speed. • Double circulation provides a vigorous flow of blood because the blood goes back to the heart after passing through only one set of capillaries. • The two circuits are: • Pulmonary – blood gets oxygenated in the lungs. • Systemic – blood goes to all the tissues of the body.

  11. The Heart

  12. The Heart • The cardiac cycle is one cycle of the contraction phase, the systole, and the relaxation phase, the diastole. • The cardiac output is the amount of blood that the left ventricle pumps out in one minute. • Heart rate is the number of beats per minute. • Stroke volume is the amount of blood that the left ventricle pumps in one contraction.

  13. Cardiac Cycle

  14. Heart rhythm • The sinoatrial (SA) node controls the pace of the heart by sending out electrical impulses to the whole heart. • These impulses are delayed at the atrioventricular (AV) nodebefore spreading to the rest of the heart through the Purkinje fibers.

  15. Blood vessels • Arteries and veins are composed of three layers: • Elastic connective tissue on the outside. • Connective tissue and smooth muscles in the middle. • The endothelium, which are smooth, thin, and flattened cells, on the inside.

  16. Blood Pressure • The hydrostatic pressure that the blood exerts on the vessels is called blood pressure. • It is the greatest during a systole because the blood cannot flow too quickly through the arterioles into the capillaries in what is known as peripheral resistance. When the blood is forced into the arteries, the arteries expand while it is trying to squeeze into the capillaries (this pressure is known as systolic pressure). During a diastole, the pressure is lower because there is enough time for the blood to enter the capillaries (known as diastolic pressure).

  17. Blood Pressure Measuring

  18. Capillary Exchange • The exchange of nutrients and gases between the blood and the interstitial fluid occurs in the capillaries. • Because of the high pressure in the capillaries, some of the blood plasma gets pushed into the interstitial fluid. Though, most of it returns because of osmotic pressure. • The rest enters the lymphatic system which later drains into the circulatory system.

  19. Blood • Blood is composed about 55% of plasma. • Plasma is connective tissue that is mostly composed of water. The rest includes ions, nutrients, plasma proteins, waste products of metabolism, respiratory gases, and hormones. • The other 45% of blood is cellular mass.

  20. Blood • The cellular mass of blood is composed of erythrocytes, leukocytes, and platelets. • Erythrocytes help with the transport of oxygen and carbon dioxide. • Leukocytes are involved in the body defense. • Platelets help with blood clotting.

  21. Blood Clotting • When there is damage to the blood vessel, the platelets are the first on the site. • They stick to the site of injury and release chemicals which stimulate the production if fibrin. • Anticlotting factors help us by inhibiting the platelets from sticking to the sides of the vessels and creating plaque.

  22. Cardiovascular Problems • Heart attacks occur because the coronary artery became clotted by a thrombus and cardiac muscle cells of the heart have died. • Strokes occur because the blood vessels in the brain became blocked with an embolus or ruptured because of high pressure (hypertension), and the brain cells in the region died.

  23. Cardiovascular Problems • Thrombi and emboli result from atherosclerosis, or the accumulation of plaque in the blood vessels. • Causes of atherosclerosis are: • Hypertension • Smoking • High-cholesterol diet • Lack of exercise

  24. Gas Exchange • Gas exchange is defined as • Respiratory medium – the source of oxygen for the animal. Can be air or water. • Respiratory surface – the part of the animal’s body where gases are exchanged with the environment. This occurs through diffusion.

  25. Gills • Gills are respiratory adaptations of most aquatic animals • They’re outfoldings of the body surface that are suspended in water. • They get oxygen from the water by diffusion. • Ventilation helps by speeding up the movement of water past the gills. • Countercurrent exchange is a very effective and beneficial part of the gas exchange in the gills.

  26. Gills – Concurrent Exchange

  27. Tracheal System • The tracheal system is the respiratory adaptation of insects. • It consists of many tubes that reach all of the body cells. • This system of tubes is open to the air, and through complex movements of the body the insect can speed up the movement of air through the tubes.

  28. Tracheal System

  29. The Respiratory System Each lung contains ~ 2 million alveoli, with a total surface area of ~ 100 m2 .

  30. The Respiratory System Alveoli have thin, moist walls and are surrounded by capillaries

  31. The Respiratory System Oxygen diffuses from the air in the air spaces of the alveoli into the blood of the capillaries.

  32. The Respiratory System Carbon dioxide diffuses from the blood of the capillaries into the air of the air spaces of the alveoli.

  33. The Respiratory System When the diaphragm contracts, the chest cavity expands, and the lungs fill with air.

  34. The Respiratory system When the diaphragm contracts, the chest cavity expands, and the lungs fill with air.

  35. Birds have especially efficient respiratory systems When a bird inhales, some of the air passes through its lungs and some fills its air sacs.

  36. Birds have especially efficient respiratory systems When a bird exhales, air continues to move in the same direction through the lungs, as the air sacs empty.

  37. Birds have especially efficient respiratory systems The microscopic, tube-like chambers of gas exchange in bird lungs are known as parabronchi.

  38. Respiratory pigments • Respiratory pigments help with the transport of oxygen and carbon dioxide. • Hemoglobin is the respiratory pigment of almost all vertebrates; it has 4 subunits with iron atoms to which oxygen binds to. Oxygen bonded to iron gives blood the red color. • Hemocyanin is the respiratory pigment found in the hemolymph of arthropods and mollusks; it has a copper atom to which oxygen can bind to, giving the blood a pale blue color.

  39. CO2 transport • The respiratory pigments help with the transport of carbon dioxide. • Some of it goes into solution with blood plasma. • Most of it is transferred as bicarbonate. Bicarbonate results from

More Related