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Lymphatic system. Plays important role in fluid distribution Important part of the immune system Lymphatic system.

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Presentation on theme: "Lymphatic system. Plays important role in fluid distribution Important part of the immune system Lymphatic system."— Presentation transcript:

1 Lymphatic system

2 Plays important role in fluid distribution Important part of the immune system Lymphatic system


4 Edema Pulmonary edema Peripheral edema

5 Skeletal muscle pump

6 Moving Blood Back to the Heart Blood in veins is under low pressure Two major pumps assist in moving blood back to the heart Skeletal muscle Respiratory pumps Inhalation: pressure in thoracic cage drops and draws blood into veins Exhalation: pressure increases in the thoracic cage and pushes the blood towards the heart; blood does not move backwards because of valves Figure 9.38

7 Veins – volume reservoir Veins have thinner and more compliant walls Small increases in blood pressure lead to large changes in volume In mammals veins hold more than 60% of the blood

8 Regulation of circulatory systems Q = DP/R Law of Bulk flow For circulatory system CO = MAP/ TPR HR x SV = MAP/ TPR

9 Regulation of circulatory systems


11 Baroreceptor reflex Important mechanism for regulating blood pressure “Pressure” (stretch) receptors located in carotid and aortic bodies

12 Baroreceptor reflex Rapid changes in blood pressure are possible through sympathetic changes in cardiac output & arteriolar tone Baroreceptors are stretch- sensitive mechanoreceptors located in the walls of many major blood vessels Most important of these are located in the carotid artery and aorta Baroreceptor reflex regulates MAP

13 Baroreceptor discharges Most sensitive in physiological range More sensitive to pulsatile pressures

14 Arterial Pressure and blood volume Blood volume regulation via kidneys 1.Simple filtration 2.Humoral controls Renin-angiotensin system (RAS) Antidiuretic hormone (ADH)

15 Measured blood pressure when standing includes a hydrostatic (gravity) component What happens when we change body positions? Effects of gravity on blood pressure

16 Effects of gravity

17 How Does Gravity Affect Blood Circulation?

18 Very tall animals (e.g. giraffe) must be able to pump blood up to the head They could also have difficulty with blood pooling in the feet, and peripheral edema How Does Gravity Affect Blood Circulation?


20 Differences in central arterial blood pressures systole/diastole Human 120/80 Elephant 120/70 Pigeon 135/100 gill lung ventral aorta pulmonary artery aorta dorsal aorta aorta pulmonary artery systole/diastole Trout45/33 systole/diastole Turtle31/25

21 Composition of Blood Primarily water containing ions and organic solutes Blood cells Proteins

22 Blood Proteins Invertebrates: primarily respiratory pigments Vertebrates: carrier proteins such as albumin and globulins, and proteins involved in blood clotting

23 Blood Cells or Hemocytes Functions: oxygen transport or storage, nutrient transport or storage, phagocytosis, immune defense, blood clotting Figure 9.44

24 Erythrocytes Red blood cells are the most abundant cells in the blood of vertebrates Contain high concentrations of respiratory pigments such as hemoglobin Major function is the storage and transport of oxygen Have evolved independently several times

25 Vertebrate Blood Separates into three main components when centrifuged Plasma Erythrocytes Other blood cells and clotting cells Hematocrit – fraction of blood made up of erythrocytes Figure 9.45

26 Erythrocytes Round or oval in shape Mammalian erythrocytes are biconcave disks This shape increases surface area, facilitating oxygen transfer

27 Leukocytes White blood cells Function in the immune response All are nucleated Found both in the blood and the interstitial fluid Some are able to move across capillary walls Five major types Figure 9.46

28 Thrombocytes Play a key role in blood clotting Spindle-shaped cells in nonmammals and classified as leukocytes Anucleated cell fragments in mammals called platelets Three steps in blood clotting Vasoconstriction Platelet plug formation Clot formation through coagulation cascade

29 Blood Cell Formation Process is called hematopoiesis Location of stem cells Adult mammals: only in bone marrow Fishes: kidney Amphibians, reptiles, birds: spleen, liver, kidney, bone marrow Specific signaling factors are involved, e.g., erythropoietin is a hormone released by the kidney in response to low blood oxygen

30 Blood flow distribution & circulatory patterns Separation of respiratory & systemic circulations Air-breathing fishes Lungfishes Amphibians Reptiles Mammalian fetal circulation In-series circuits 1 atrium + 1 ventricle Single pump In-parallel circuits 2 atria + 1 ventricle Single pump or a functional double pump In-series circuits 2 atria + 2 ventricles Double pump Evolution of air breathing: Plumbing & pressures

31 Fish Heart has four chambers arranged in series

32 Air-Breathing Fishes Air-breathing evolved several times in fishes Air-breathing organs are arranged in parallel; oxygenated and deoxygenated blood mix Lungfish are the most specialized air-breathing fishes and have only limited mixing of the oxygenated and deoxygenated blood Various organs serve as ABOs in fish Can use: Swimbladder, mouth, gut, gills, skin, etc. Common problems: O 2 blood enters venous system  mixed venous blood Single atrium receives mixed venous blood

33 Lungfish: true lung (developmentally) Largely solved the problem of mixed venous blood Atrium has a partial septum: oxygenated on one side; deoxygenated on the other Ventricle has partial septum: separation maintained Outflow vessel has a partial septum: separation is maintained Lungfish

34 Amphibians and Reptiles Like lungfish, the heart is only partially divided; two atria and one ventricle Oxygenated and deoxygenated blood can mix Two streams of blood are kept fairly separate although the mechanism is not completely understood Crocodilians have a completely divided ventricle

35 Anatomically undivided heart, in-parallel circulations Amphibians heart systemic capillaries pulmonary capillaries The beauty vagal vasoconstriction can close off lung circulation during breath-hold or diving Single ventricle Blood mixing Single outflow vessel High lung pressure Two atria Separate pulmonary & systemic venous return Solutions Trabecular heart Spiral valve Lymph hearts

36 Amphibian heart Spongy myocardium & spiral valve in conus help separate oxygenated & deoxygenated blood within the single ventricle Three chambered heart: two atria and one ventricle Trabeculae within the ventricle and a spiral fold within the conus arteriosus help to keep oxygenated and deoxygenated blood separate

37 Spongy myocardium & ventricular septa (creating cava) helps separate oxygenated & deoxygenated blood within the single ventricle Right atrium largely to cavum pulmonale Two outflow vessels: pulmonary & systemic arteries Reptilian hearts: 3 major strategies 1. Anatomically undivided heart, in-parallel circulations Blood pressures in cavum venosum, cavum pulmonale & cavum arteriosum are identical during ventricular contraction Pulmonary capillaries protected by outflow resistance site (vagal constriction) Squamate lizards, turtles, tortoises & most snakes

38 Highly developed ventricular muscular ridge Systolic pressure in cavum pulmonale is lower than cavum arteriosum, but no difference during diastole: low pulmonary pressure = functional, but not anatomical separation Reptilian hearts: 3 major strategies 2. Functionally divided heart, in-parallel circulations Varanid lizards & pythons

39 3. Anatomically divided heart, double circulation with a by-pass Crocodilian heart: best of both worlds: heart  pulmonary capillaries  heart  systemic capillaries Powered by 2 atria & 2 ventricles with same wall thickness Cog valve Can close off lung circulation (vagal vasoconstriction) Right ventricle has pulmonary artery & a right systemic aorta Left ventricle has a “left” systemic aorta Foramen of Panizza provides a pressure connection between “left” & “right” aortae

40 Reptiles Can shunt blood to bypass either the pulmonary or systemic circuit Right-to-left shunt: deoxygenated blood bypasses the pulmonary circuit and reenters the systemic circuit Left-to-right shunt: some pulmonary blood reenters the pulmonary circuit Figure 9.16a

41 Mammalian fetal circulation No air ventilation of lungs O 2 comes from placenta In-series circuits 2 atria + 2 ventricles Double pump Low pulmonary pressure placenta

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