Chapter 42 Circulation and Gas Exchange. Material Exchange The exchange of materials from inside to...
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Chapter 42Chapter 42
Circulation and Gas ExchangeCirculation and Gas Exchange
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Material ExchangeMaterial Exchange
• The exchange of materials from inside to outside is an important function for organisms.
• It’s easy for unicellular organisms.
• It becomes more difficult for multicellular organisms.
• Complex organ systems have evolved to move materials throughout an organism.
• The exchange of materials from inside to outside is an important function for organisms.
• It’s easy for unicellular organisms.
• It becomes more difficult for multicellular organisms.
• Complex organ systems have evolved to move materials throughout an organism.
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DiffusionDiffusion
• Diffusion takes time.• It is difficult to move substances more than a few millimeters with diffusion.
• Circulatory systems evolved to circumvent this problem.
• Bulk movement coupled with diffusion across small distances.
• Diffusion takes time.• It is difficult to move substances more than a few millimeters with diffusion.
• Circulatory systems evolved to circumvent this problem.
• Bulk movement coupled with diffusion across small distances.
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InvertebratesInvertebrates
• Many animals have a simple body plan and don’t require a circulatory system.
• These animals have a thin gastrovascular system (2 cells thick).
• Materials enter and exit through a single opening and nutrients/wastes diffuse through the thin cell layer.
• Many animals have a simple body plan and don’t require a circulatory system.
• These animals have a thin gastrovascular system (2 cells thick).
• Materials enter and exit through a single opening and nutrients/wastes diffuse through the thin cell layer.
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Other AnimalsOther Animals
• Many animals consist of multiple cell layers and diffusion becomes inefficient.
• 2 circulatory systems have evolved in invertebrates to accommodate this:
• 1. Open• 2. Closed
• Many animals consist of multiple cell layers and diffusion becomes inefficient.
• 2 circulatory systems have evolved in invertebrates to accommodate this:
• 1. Open• 2. Closed
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1. Open Circulatory Systems
1. Open Circulatory Systems
• Invertebrates.• There is no distinction between blood and interstitial fluid.
• It is called hemolymph.
• Invertebrates.• There is no distinction between blood and interstitial fluid.
• It is called hemolymph.
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2. Closed Circulatory System
2. Closed Circulatory System
• Invertebrates.• Blood is confined to vessels and is distinct from interstitial fluid.
• Both systems have 3 basic components:
• 1. Circulatory fluid (blood)
• 2. A set of tubes (blood vessels)
• 3. A muscular pump (heart)
• Invertebrates.• Blood is confined to vessels and is distinct from interstitial fluid.
• Both systems have 3 basic components:
• 1. Circulatory fluid (blood)
• 2. A set of tubes (blood vessels)
• 3. A muscular pump (heart)
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The Pump of Circulatory Systems
The Pump of Circulatory Systems
• 1. “Single” chambered hearts• Example: earthworm-peristalsis pumps blood.
• 2. 2 chambered hearts• Example: fish
• 1. “Single” chambered hearts• Example: earthworm-peristalsis pumps blood.
• 2. 2 chambered hearts• Example: fish
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The Pump of Circulatory Systems
The Pump of Circulatory Systems
• 3. 3 chambered hearts• Example: amphibians and reptiles (not birds), pulmocutaneous circuit picks up O2, and the heart pumps the blood through the system.
• 4. 4 chambered hearts• Example: mammals and birds, a pulmonary circuit picks up O2 and returns it to the heart. The heart distributes the oxygenated blood to the rest of the body.
• 3. 3 chambered hearts• Example: amphibians and reptiles (not birds), pulmocutaneous circuit picks up O2, and the heart pumps the blood through the system.
• 4. 4 chambered hearts• Example: mammals and birds, a pulmonary circuit picks up O2 and returns it to the heart. The heart distributes the oxygenated blood to the rest of the body.
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Circulatory SystemsCirculatory Systems
• The heart acts to increase the hydrostatic pressure which flows down a pressure gradient and back to the heart.
• Blood pressure is the motive force that moves the fluid through the circulatory system.
• Both open and closed systems are widespread throughout the animal kingdom.
• The heart acts to increase the hydrostatic pressure which flows down a pressure gradient and back to the heart.
• Blood pressure is the motive force that moves the fluid through the circulatory system.
• Both open and closed systems are widespread throughout the animal kingdom.
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Circulatory SystemsCirculatory Systems
• Both open and closed have their advantages and disadvantages.
• Both open and closed have their advantages and disadvantages.
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Circulatory Systems--Open
Circulatory Systems--Open
• Open systems have lower hydrostatic pressure.
• They are less costly in terms of metabolic energy expenditure for construction and maintenance.
• Open systems have lower hydrostatic pressure.
• They are less costly in terms of metabolic energy expenditure for construction and maintenance.
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Circulatory Systems--Closed
Circulatory Systems--Closed
• They can achieve a higher blood pressure.
• They are more effective at transporting materials.
• They can accommodate larger, more active animals.
• They can achieve a higher blood pressure.
• They are more effective at transporting materials.
• They can accommodate larger, more active animals.
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Vertebrate CirculationVertebrate Circulation
• Vertebrates generally have 1 or 2 atria, and 1 or 2 ventricles.
• It is a closed system.• Cardiovascular.• Atria receive blood• Ventricles pump blood
• Vertebrates generally have 1 or 2 atria, and 1 or 2 ventricles.
• It is a closed system.• Cardiovascular.• Atria receive blood• Ventricles pump blood
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3 Main Blood Vessel Types
3 Main Blood Vessel Types
• 1. Arteries--carry blood away from the heart.
• 2. Veins--carry blood to the heart.
• 3. Capillaries--the spots where arteries and veins meet and nutrient exchange occurs.
• 1. Arteries--carry blood away from the heart.
• 2. Veins--carry blood to the heart.
• 3. Capillaries--the spots where arteries and veins meet and nutrient exchange occurs.
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Blood Vessel TypesBlood Vessel Types
• Networks of capillaries infiltrate each tissue and exchange many nutrients with the tissues.
• Arterioles are the sites where small vessels convey blood to the capillaries.
• At the downstream end, capillaries converge into venules which converge into veins.
• Networks of capillaries infiltrate each tissue and exchange many nutrients with the tissues.
• Arterioles are the sites where small vessels convey blood to the capillaries.
• At the downstream end, capillaries converge into venules which converge into veins.
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Different Circulation Systems
Different Circulation Systems
• Single circulation-invertebrates. Blood or hemolymph passes through one or more hearts on its way through the organism.
• Pulmocutaneous circulation-amphibians. Blood passes through the lungs and skin picking up O2 and giving off CO2.
• Single circulation-invertebrates. Blood or hemolymph passes through one or more hearts on its way through the organism.
• Pulmocutaneous circulation-amphibians. Blood passes through the lungs and skin picking up O2 and giving off CO2.
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Different Circulation Systems
Different Circulation Systems
• Double circulation-blood passes through a 3 (reptiles) or 4 (mammals & birds) chambered heart twice.
• The first time, as CO2 rich blood.
• The second time as O2 rich blood.
• Double circulation-blood passes through a 3 (reptiles) or 4 (mammals & birds) chambered heart twice.
• The first time, as CO2 rich blood.
• The second time as O2 rich blood.
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A Pulmocutaneous Circuit
A Pulmocutaneous Circuit
• A pulmocutaneous circuit leads to capillaries in the gas exchange organs--lungs and skin.
• Most of the O2 rich blood is pumped into the systemic circuit which supplies O2 to the rest of the body.
• A pulmocutaneous circuit leads to capillaries in the gas exchange organs--lungs and skin.
• Most of the O2 rich blood is pumped into the systemic circuit which supplies O2 to the rest of the body.
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A Pulmocutaneous Circuit
A Pulmocutaneous Circuit
• There is some mixing of the O2 rich and CO2 rich blood.
• A ridge in the ventricle diverts most of the O2 rich blood to the systemic circuit.
• There is some mixing of the O2 rich and CO2 rich blood.
• A ridge in the ventricle diverts most of the O2 rich blood to the systemic circuit.
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Double CirculationDouble Circulation
• The organization called double circulation provides for vigorous blood flow.
• Blood gets pumped a second time after leaving the capillaries.
• Reptiles have double circulation with a pulmonary circuit.
• The organization called double circulation provides for vigorous blood flow.
• Blood gets pumped a second time after leaving the capillaries.
• Reptiles have double circulation with a pulmonary circuit.
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Double CirculationDouble Circulation
• Some of these circuits contain a 3 chambered heart--amphibians, reptiles.
• The ventricle is partially divided by a septum to reduce blood mixing.
• Double circulation restores pressure to the systemic circuit after blood has passed through the lung capillaries.
• Some of these circuits contain a 3 chambered heart--amphibians, reptiles.
• The ventricle is partially divided by a septum to reduce blood mixing.
• Double circulation restores pressure to the systemic circuit after blood has passed through the lung capillaries.
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Double CirculationDouble Circulation• Double circulation contrasts with single circulation seen in fish.
• In fish, the blood flows from the respiratory organs to the other organs under pressure.
• In double circulation pressure is restored to the systemic circuit after blood has passed through the lung capillaries.
• Double circulation contrasts with single circulation seen in fish.
• In fish, the blood flows from the respiratory organs to the other organs under pressure.
• In double circulation pressure is restored to the systemic circuit after blood has passed through the lung capillaries.
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Advantages of a 4 Chambered Heart
Advantages of a 4 Chambered Heart
• The 4 chambered heart was an essential adaptation.• It helps support the endothermy.
• It delivers the high quantity of O2 and fuel necessary for metabolism.
• It removes wastes produced via metabolism.
• This movement of substances is made possible by the separate systemic and pulmonary circuits and the 4 chambered heart.
• The 4 chambered heart was an essential adaptation.• It helps support the endothermy.
• It delivers the high quantity of O2 and fuel necessary for metabolism.
• It removes wastes produced via metabolism.
• This movement of substances is made possible by the separate systemic and pulmonary circuits and the 4 chambered heart.
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The 4 Chambered HeartThe 4 Chambered Heart• Consists mostly of cardiac muscle.
• It goes through a series of rhythmic contractions and relaxations to move blood.
• When the chambers relax they fill; when they contract, they empty.
• Systole-contraction• Diastole-relaxation
• Consists mostly of cardiac muscle.
• It goes through a series of rhythmic contractions and relaxations to move blood.
• When the chambers relax they fill; when they contract, they empty.
• Systole-contraction• Diastole-relaxation
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The 4 Chambered HeartThe 4 Chambered Heart• Ventricles are usually larger because they move more blood.
• The AV valve is between the atria and ventricles.
• They prevent the backflow of blood during contraction.
• Semilunar valves prevent backflow of blood while it’s in the aorta.
• Ventricles are usually larger because they move more blood.
• The AV valve is between the atria and ventricles.
• They prevent the backflow of blood during contraction.
• Semilunar valves prevent backflow of blood while it’s in the aorta.
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Heart RhythmHeart Rhythm• Maintaining rhythm is important because O2 is very important.
• Some cardiac muscles are self-excitable and do not need any input from the nervous system to contract.
• The heart’s pacemaker is the SA node.
• Maintaining rhythm is important because O2 is very important.
• Some cardiac muscles are self-excitable and do not need any input from the nervous system to contract.
• The heart’s pacemaker is the SA node.
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The SA NodeThe SA Node• It sets the rate and timing of heart contractions.
• It is located in the wall of the right atrium and is made of specialized cells.• Myogenic hearts have a pacemaking ability that originates in the heart.
• Neurogenic hearts have contractions that originate from motor nerves.
• It sets the rate and timing of heart contractions.
• It is located in the wall of the right atrium and is made of specialized cells.• Myogenic hearts have a pacemaking ability that originates in the heart.
• Neurogenic hearts have contractions that originate from motor nerves.
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The SA NodeThe SA Node• The SA node generates electrical impulses similar to those produced by nerve cells.
• The cardiac muscle contains the SA node that sets the tempo for the entire heart.
• The impulse is quickly passed through the muscles and passes a relay point called the AV node.
• The SA node generates electrical impulses similar to those produced by nerve cells.
• The cardiac muscle contains the SA node that sets the tempo for the entire heart.
• The impulse is quickly passed through the muscles and passes a relay point called the AV node.
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The AV nodeThe AV node• The AV node is located in the wall between the right atrium and right ventricle.
• The AV node slightly delays the signal impulse.
• The delay ensures that the atria empty before the ventricles contract.
• The AV node is located in the wall between the right atrium and right ventricle.
• The AV node slightly delays the signal impulse.
• The delay ensures that the atria empty before the ventricles contract.
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Purkinje FibersPurkinje Fibers
• These are specialized muscle fibers that conduct signals to the apex of the heart and throughout the ventricles.
• These are specialized muscle fibers that conduct signals to the apex of the heart and throughout the ventricles.
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The HeartThe Heart
• Although the SA node sets the tempo for the heart, it is innervated by 2 nerves that affect heart rate.
• One speeds it up.• The other slows it down.• Hormones, body temperature, and physical activity also have an effect on heart rate.
• Although the SA node sets the tempo for the heart, it is innervated by 2 nerves that affect heart rate.
• One speeds it up.• The other slows it down.• Hormones, body temperature, and physical activity also have an effect on heart rate.
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Blood VesselsBlood Vessels• Arteries and veins.• They are all built from similar tissues:
• 1. The outside layer consists of connective tissue with elastic fibers.
• This allows for functional stretch and recoil.
• Arteries and veins.• They are all built from similar tissues:
• 1. The outside layer consists of connective tissue with elastic fibers.
• This allows for functional stretch and recoil.
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Blood VesselsBlood Vessels• 2. The middle layer consists of smooth muscle and more elastic fibers.
• 3. The inner layer is lined with a smooth layer of flattened endothelial cells.
• 2. The middle layer consists of smooth muscle and more elastic fibers.
• 3. The inner layer is lined with a smooth layer of flattened endothelial cells.
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ArteriesArteries
• Arteries have thicker walls and are more elastic.
• They are for pumping quickly at high pressure.
• Their elastic walls allow for pressure to remain high even when the heart isn’t contracting.
• Arteries have thicker walls and are more elastic.
• They are for pumping quickly at high pressure.
• Their elastic walls allow for pressure to remain high even when the heart isn’t contracting.
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CapillariesCapillaries• These are different from arteries and veins.
• They lack the 2 outer layers (connective tissue and smooth muscle) and consist of only endothelial cells.
• This facilitates the exchange of materials between blood and interstitial fluid.
• These are different from arteries and veins.
• They lack the 2 outer layers (connective tissue and smooth muscle) and consist of only endothelial cells.
• This facilitates the exchange of materials between blood and interstitial fluid.
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CapillariesCapillaries• Generally, the smaller the diameter of the pipe, the faster liquid has to flow.
• Due to the large cross-sectional area of capillaries, blood moves very slowly through them.
• Blood pressure is low at the capillary due to the resistance encountered.
• Generally, the smaller the diameter of the pipe, the faster liquid has to flow.
• Due to the large cross-sectional area of capillaries, blood moves very slowly through them.
• Blood pressure is low at the capillary due to the resistance encountered.
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CapillariesCapillaries
• As the blood leaves the capillary, it speeds back up as it enters the vein.
• As the blood leaves the capillary, it speeds back up as it enters the vein.
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VeinVein• Veins have thinner walls.
• The blood moves slower through them and is under low pressure.
• The movement is facilitated by muscle contraction.
• Veins have valves that prevent the backflow of blood down the vein due to low pressure.
• Veins have thinner walls.
• The blood moves slower through them and is under low pressure.
• The movement is facilitated by muscle contraction.
• Veins have valves that prevent the backflow of blood down the vein due to low pressure.
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VeinsVeins
• Blood returns to the heart via action of smooth muscles in the venules and veins.
• Contraction of skeletal muscle greatly assists movement of the blood.
• Blood returns to the heart via action of smooth muscles in the venules and veins.
• Contraction of skeletal muscle greatly assists movement of the blood.
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Blood Flow Through Capillaries
Blood Flow Through Capillaries
• There are 2 mechanisms that regulate the distribution of blood flow through the capillaries:
• 1. Smooth muscle constricts, decreasing the diameter of the arteriole reducing blood flow through it.
• There are 2 mechanisms that regulate the distribution of blood flow through the capillaries:
• 1. Smooth muscle constricts, decreasing the diameter of the arteriole reducing blood flow through it.
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Blood Flow Through Capillaries
Blood Flow Through Capillaries
• 2. Precapillary sphincters that control the flow of blood through the arterioles and sphincters.
• 2. Precapillary sphincters that control the flow of blood through the arterioles and sphincters.
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In The Capillary BedsIn The Capillary Beds
• Substances move in and out by diffusion, endocytosis, and exocytosis.
• There are many clefts between the endothelial cells--diffusion occurs here.
• Blood pressure is largely responsible for movement of materials through the clefts however.
• Substances move in and out by diffusion, endocytosis, and exocytosis.
• There are many clefts between the endothelial cells--diffusion occurs here.
• Blood pressure is largely responsible for movement of materials through the clefts however.
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In The Capillary BedsIn The Capillary Beds• Many substances are too large to cross the endothelium.
• Osmotic pressure between the arteriole and venule remains constant.
• However, blood pressure drops significantly between the arteriole and venule.
• Many substances are too large to cross the endothelium.
• Osmotic pressure between the arteriole and venule remains constant.
• However, blood pressure drops significantly between the arteriole and venule.
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In The Capillary BedsIn The Capillary Beds• At the arteriole end, blood pressure is high compared to the osmotic pressure.
• Fluids flow out of the arteriole and into the interstitial fluid.
• At the arteriole end, blood pressure is high compared to the osmotic pressure.
• Fluids flow out of the arteriole and into the interstitial fluid.
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In The Capillary BedsIn The Capillary Beds• At the venule end, the blood pressure is low compared to the osmotic pressure.
• Fluid flows into the venule from the interstitial fluid.
• 85% of the fluid lost from the arteriole end is recovered.
• 15% of the fluid is recovered by the lymphatic system.
• At the venule end, the blood pressure is low compared to the osmotic pressure.
• Fluid flows into the venule from the interstitial fluid.
• 85% of the fluid lost from the arteriole end is recovered.
• 15% of the fluid is recovered by the lymphatic system.
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Lymphatic SystemLymphatic System• The fluid of the lymphatic system is called lymph.• It has roughly the same composition as interstitial fluid.
• Lymph capillaries are interspersed throughout the cardiovascular capillaries.
• These assist with the reabsorption of fluid.
• The fluid of the lymphatic system is called lymph.• It has roughly the same composition as interstitial fluid.
• Lymph capillaries are interspersed throughout the cardiovascular capillaries.
• These assist with the reabsorption of fluid.
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Lymphatic SystemLymphatic System
• The lymph vessels are very similar to veins.
• They have valves that prevent the backflow.
• Rhythmic contractions of smooth muscle assist in lymph flow.
• Skeletal muscle contractions are the main sources of lymph movement.
• The lymph vessels are very similar to veins.
• They have valves that prevent the backflow.
• Rhythmic contractions of smooth muscle assist in lymph flow.
• Skeletal muscle contractions are the main sources of lymph movement.
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Lymphatic SystemLymphatic System• Lymph nodes are lymph vessel organs.
• They contain WBC’s (lymphocytes) and cells specialized for defense (macrophages).
• They filter the lymph and attack foreign invaders (antigens).
• They often swell when we are ill.
• Lymph nodes are lymph vessel organs.
• They contain WBC’s (lymphocytes) and cells specialized for defense (macrophages).
• They filter the lymph and attack foreign invaders (antigens).
• They often swell when we are ill.
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Blood CellsBlood Cells• Blood cells and cell fragments occupy about 45% of the blood volume.• 55% is plasma.• Plasma is 90% water, it contains electrolytes.
• Plasma proteins help to maintain pH, osmotic balance, and blood viscosity.
• Some of these proteins are immunoglobulins that function in defense.
• Blood cells and cell fragments occupy about 45% of the blood volume.• 55% is plasma.• Plasma is 90% water, it contains electrolytes.
• Plasma proteins help to maintain pH, osmotic balance, and blood viscosity.
• Some of these proteins are immunoglobulins that function in defense.
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PlasmaPlasma
• Blood plasma suspends 3 elements:
• 1. RBC’s--oxygen transport, most numerous.
• 2. WBC’s--defense of body.
• 3. Platelets--fragments of cells which help in the clotting process.
• Blood plasma suspends 3 elements:
• 1. RBC’s--oxygen transport, most numerous.
• 2. WBC’s--defense of body.
• 3. Platelets--fragments of cells which help in the clotting process.
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This image is copyright Dennis Kunkel
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1. Red Blood Cells1. Red Blood Cells• Shape is related to its function.
• Biconcave increases its surface area.
• Small size and number increases surface area--related to function.
• Mammalian lack nuclei--allows for more hemoglobin.
• Shape is related to its function.
• Biconcave increases its surface area.
• Small size and number increases surface area--related to function.
• Mammalian lack nuclei--allows for more hemoglobin.
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1. Red Blood Cells1. Red Blood Cells
• RBC production is stimulated by a negative feedback mechanism.
• When the amount of O2 reaching body tissues decreases, this stimulates the kidney to synthesize EPO.
• When more O2 reaches the tissues, EPO levels fall and erythrocyte production slows.
• RBC production is stimulated by a negative feedback mechanism.
• When the amount of O2 reaching body tissues decreases, this stimulates the kidney to synthesize EPO.
• When more O2 reaches the tissues, EPO levels fall and erythrocyte production slows.
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Heart DiseaseHeart Disease• LDL’s are bad.• HDL’s are good.• Cholesterol is bad in large quantities.
• It sticks to the inside walls of arteries and results in a narrowing of the arteries, a stiffening of their walls (called atherosclerosis).
• This increases the risk of heart attack and stroke.
• LDL’s are bad.• HDL’s are good.• Cholesterol is bad in large quantities.
• It sticks to the inside walls of arteries and results in a narrowing of the arteries, a stiffening of their walls (called atherosclerosis).
• This increases the risk of heart attack and stroke.
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2. Leukocytes (WBC’s)2. Leukocytes (WBC’s)
• These are white blood cells and there are 5 types:• 1. Monocytes• 2. Neutrophils• 3. Basophils• 4. Eosinophils• 5. Lymphocytes
• Collectively, these fight infection.
• These are white blood cells and there are 5 types:• 1. Monocytes• 2. Neutrophils• 3. Basophils• 4. Eosinophils• 5. Lymphocytes
• Collectively, these fight infection.
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The Contents of BloodThe Contents of Blood
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Erythrocytes
NeutrophilLymphocyte
Monocyte
Eosinophil
Platelets
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Basophil
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2. Leukocytes (WBC’s)2. Leukocytes (WBC’s)
• These spend most of their time in the interstitial fluid where they fight invaders.
• These spend most of their time in the interstitial fluid where they fight invaders.
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Stem CellsStem Cells
• Recall that they are pluripotent.
• They can develop into many different types of things:• 1. Erythrocytes• 2. Leukocytes• 3. Platelets
• They are found in bone marrow.
• Recall that they are pluripotent.
• They can develop into many different types of things:• 1. Erythrocytes• 2. Leukocytes• 3. Platelets
• They are found in bone marrow.
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3. Platelets3. Platelets
• These plug wounds and prevent blood loss.
• Wounds release factors that make platelets sticky and enable them to adhere to collagen fibers in connective tissue slowing blood loss.
• These plug wounds and prevent blood loss.
• Wounds release factors that make platelets sticky and enable them to adhere to collagen fibers in connective tissue slowing blood loss.
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Respiratory SystemRespiratory System
• Respiratory surfaces allow for the exchange of gases.
• They are always thin and bathed in water.
• In most animals, the respiratory medium is a thin, moist epithelium.
• This separates the respiratory medium from the blood.
• Respiratory surfaces allow for the exchange of gases.
• They are always thin and bathed in water.
• In most animals, the respiratory medium is a thin, moist epithelium.
• This separates the respiratory medium from the blood.
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Respiratory SystemRespiratory System
• In animals that don’t respire through their skin, there are three common respiratory surfaces:
• 1. Gills• 2. Trachea• 3. Lungs
• In animals that don’t respire through their skin, there are three common respiratory surfaces:
• 1. Gills• 2. Trachea• 3. Lungs
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1. Gills1. Gills
• Are out-foldings of the body surface suspended in water.
• They are loaded with capillaries.
• Animals with gills ventilate them which moves water with a high concentration of O2 over them.
• Are out-foldings of the body surface suspended in water.
• They are loaded with capillaries.
• Animals with gills ventilate them which moves water with a high concentration of O2 over them.
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1. Gills1. Gills• Blood moves in an opposite direction to the movement of water past the gills.
• The O2 transfer is highly efficient.• This is called counter-current exchange, and loads the blood with O2.
• It keeps a diffusion gradient over the entire length of the capillary.
• Blood moves in an opposite direction to the movement of water past the gills.
• The O2 transfer is highly efficient.• This is called counter-current exchange, and loads the blood with O2.
• It keeps a diffusion gradient over the entire length of the capillary.
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2. Tracheal System2. Tracheal System• Found in insects.• It is made up of tubes that branch through the body which is a variation on a folded, internal respiratory surface.
• The trachea branches smaller and smaller and contacts nearly every cell.
• Found in insects.• It is made up of tubes that branch through the body which is a variation on a folded, internal respiratory surface.
• The trachea branches smaller and smaller and contacts nearly every cell.
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3. Lungs3. Lungs
• These are respiratory organs found in one spot of the body.
• They have a dense net of capillaries immediately below the epithelium on the respiratory surface.
• They are connected to a closed system that transports gases to and from other regions of the body.
• These are respiratory organs found in one spot of the body.
• They have a dense net of capillaries immediately below the epithelium on the respiratory surface.
• They are connected to a closed system that transports gases to and from other regions of the body.
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Air PathwayAir Pathway
• Nares pharynx, larynx, trachea, bronchi, bronchioles, alveoli
• It is like a tree tipped upside down.
• The epithelial lining of the three major branches of the respiratory system are covered by cilia and a thin film of mucus.
• Nares pharynx, larynx, trachea, bronchi, bronchioles, alveoli
• It is like a tree tipped upside down.
• The epithelial lining of the three major branches of the respiratory system are covered by cilia and a thin film of mucus.
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Air PathwayAir Pathway
• The mucus traps particulate matter and the cilia sweeps it out.
• The thinnest bronchioles are dead end sacs called alveoli, have a high SA.
• O2 dissolves in the moist film covering the epithelium and quickly diffuses into the web of capillaries surrounding the alveolus.
• CO2 diffuses in the opposite direction.
• The mucus traps particulate matter and the cilia sweeps it out.
• The thinnest bronchioles are dead end sacs called alveoli, have a high SA.
• O2 dissolves in the moist film covering the epithelium and quickly diffuses into the web of capillaries surrounding the alveolus.
• CO2 diffuses in the opposite direction.
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BreathingBreathing
• The diffusion of a gas depends on partial pressures.
• When water is exposed to air, the amount of gas dissolved in the water is proportional to the partial pressure in the air, and its solubility in water.
• Gases always diffuse from regions of high partial pressure to regions of low partial pressure.
• The diffusion of a gas depends on partial pressures.
• When water is exposed to air, the amount of gas dissolved in the water is proportional to the partial pressure in the air, and its solubility in water.
• Gases always diffuse from regions of high partial pressure to regions of low partial pressure.
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BreathingBreathing
• Positive pressure breathing-amphibians
• Negative pressure breathing-humans• Tidal volume is the volume of air inhaled with each breath.• Max. during forced breathing is 3-4.8L
• Residual volume is the amount remaining in the lungs after a forced exhale.
• Positive pressure breathing-amphibians
• Negative pressure breathing-humans• Tidal volume is the volume of air inhaled with each breath.• Max. during forced breathing is 3-4.8L
• Residual volume is the amount remaining in the lungs after a forced exhale.
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BreathingBreathing
• Human breathing is mostly under autonomic control.
• 2 regions of the brain control this:• The pons and the medulla.
• The pons controls the medulla which sets a basic breathing rhythm.
• Human breathing is mostly under autonomic control.
• 2 regions of the brain control this:• The pons and the medulla.
• The pons controls the medulla which sets a basic breathing rhythm.
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BreathingBreathing
• Sensors in the aorta and carotid arteries exert secondary control over breathing.
• These sensors monitor O2, CO2 and blood pH.
• The pH is largely controlled by CO2 levels.
• Sensors in the aorta and carotid arteries exert secondary control over breathing.
• These sensors monitor O2, CO2 and blood pH.
• The pH is largely controlled by CO2 levels.
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BreathingBreathing
• When CO2 levels increase, carbonic acid levels increase lowering the blood pH.
• When pH drops, the depth and rate of breathing increases helping to remove excess CO2.
• O2 levels only have an effect on breathing rate at high altitudes.
• When CO2 levels increase, carbonic acid levels increase lowering the blood pH.
• When pH drops, the depth and rate of breathing increases helping to remove excess CO2.
• O2 levels only have an effect on breathing rate at high altitudes.
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BreathingBreathing
• In addition to transporting O2, hemoglobin helps transport CO2 and assists in buffering.
• Respiring cells produce CO2. Carbonic anhydrase catalyzes the reaction of CO2 with H2O to form H2CO3.
• H2CO3 dissociates into H+ + HCO3-
• Most of the H+ attaches to hemoglobin and other proteins minimizing the change in blood pH.
• In addition to transporting O2, hemoglobin helps transport CO2 and assists in buffering.
• Respiring cells produce CO2. Carbonic anhydrase catalyzes the reaction of CO2 with H2O to form H2CO3.
• H2CO3 dissociates into H+ + HCO3-
• Most of the H+ attaches to hemoglobin and other proteins minimizing the change in blood pH.
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BreathingBreathing
• HCO3- diffuses into the plasma.
• As blood flows through the lungs, the process is reversed.
• Diffusion of CO2 out of the blood shifts the chemical equilibrium in favor of the conversion of HCO3
- to CO2.
• HCO3- diffuses into the plasma.
• As blood flows through the lungs, the process is reversed.
• Diffusion of CO2 out of the blood shifts the chemical equilibrium in favor of the conversion of HCO3
- to CO2.