23.1 Circulatory systems facilitate exchange with all body tissues
● To sustain life, an animal must
○ acquire nutrients,
○ exchange gases, and
○ dispose of waste products.
● In most animals, circulatory systems facilitate these exchanges.
● An internal transport system must bring resources close enough to cells for diffusion to be effective.
● A gastrovascular cavity in cnidarians and flatworms
○ functions in digestion and
○ distributes substances throughout the body.
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○ absorbs and distributes nutrients throughout the organism’s body
○ gastrovascular cavities are not effective in larger animals
● Animals with thick, multiple layers of cells use a true circulatory system that consists of ○ a muscular pump (heart) ,
○ a circulatory fluid (blood), and
○ a set of tubes (vessels) to carry the circulatory fluid.
● Open circulatory systems are found in all arthropods and most molluscs and consist of ○ a tubular heart,
○ open-ended vessels, and
○ blood that directly bathes the cells and functions as the interstitial fluid. Don't forget about the age old question of How does the mother behave in avoidant attachment style?
● Closed circulatory systems are found in vertebrates, earthworms, squids, and octopuses and consist of a circulatory fluid, blood, that is confined to vessels, keeping blood distinct from the interstitial fluid.
● The vertebrate circulatory system is often called a cardiovascular system, with three main types of vessels.
○ Arteries carry blood away from the heart to body organs and tissues.
○ Veins return blood to the heart. Don't forget about the age old question of Why is legalism not considered confucian?
○ Capillaries convey blood between arteries and veins within each tissue.
● The cardiovascular system of a fish includes a heart with two main chambers: ○ The atrium receives blood from veins.
○ The ventricle pumps blood to gills via large arteries.
● These large arteries branch into arterioles, which give rise to capillaries, which branch into networks called capillary beds, which infiltrate every organ and tissue in the body. ● Capillaries converge into venules, which in turn converge into larger veins that return blood to the heart.
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23.2 Vertebrate cardiovascular systems reflect evolution
● Blood passes through the heart of a fish once in each circuit through the body, an arrangement called single circulation.
● A single circuit would not supply enough pressure to move blood through the capillaries of the lungs and then to the body capillaries of a terrestrial vertebrate.
● Land vertebrates have a double circulation in which blood is pumped a second time after it loses pressure in the lungs.
○ The pulmonary circuit carries blood between the heart and gas exchange tissues in the lungs.
○ The systemic circuit carries blood between the heart and the rest of the body.
● Frogs and other amphibians have a three-chambered heart.
○ The right atrium receives blood returning from the systemic capillaries in the body’s organs. If you want to learn more check out What are the disadvantages of databases?
○ The ventricle pumps blood to the lungs and skin.
○ Because gas exchange occurs both in the lungs and across the thin, moist skin, this is called a pulmocutaneous circuit. We also discuss several other topics like What is the general conditions of the early jails in america?
● Although blood from the two atria mixes in the single ventricle, a ridge diverts most of the oxygen-poor blood to the pulmocutaneous circuit and most of the oxygen-rich blood to the systemic circuit.
○ In the three-chambered heart of turtles, snakes, and lizards,
■ the ventricle is partially divided, and
■ less mixing of blood occurs.
○ The ventricle is completely divided in crocodilians
● In all birds and mammals, the heart has four chambers:
○ two atria and
○ two ventricles.
● The right side of the heart handles only oxygen-poor blood.
● The left side receives and pumps only oxygen-rich blood.
The Human Cardiovascular System and Heart
23.3 The human cardiovascular system illustrates the double circulation of mammals ● Blood flow through the double circulatory system of humans
○ drains from the superior vena cava (from the head and arms) or inferior vena cava (from the lower trunk and legs) into the right atrium,
○ moves out to the lungs via the pulmonary artery,
○ returns to the left atrium through the pulmonary vein, and
○ leaves the heart through the aorta.
23.4 The heart contracts and relaxes rhythmically
● Your heart is
○ about the size of a clenched fish,
○ enclosed in a sac just under the sternum (breastbone), and
○ formed mostly of cardiac muscle tissue.
● The heart separately but simultaneously pumps
○ oxygen-poor blood to the lungs and
○ oxygen-rich blood to the body.
● One-way valves keep the blood flowing in one direction through the heart. ● The heart contracts and relaxes in a rhythmic sequence known as the cardiac cycle. The cycle consists of two main phases.
○ When the heart is relaxed, called diastole, blood flows from veins into heart chambers. ○ During the contraction phase of the cardiac cycle, called systole, blood flows from atria into ventricles.
● Cardiac output is the volume of blood that each ventricle pumps per minute.
● Heart rate is the number of heartbeats per minute.
23.5 The SA node sets the tempo of the heartbeat
● The SA (sinoatrial) node
○ generates electrical impulses in atria and
○ sets the rate of heart contractions.
● The AV (atrioventricular) node
○ relays these signals to the ventricles and
○ triggers ventricular contractions.
● An electrocardiogram (ECG)
○ detects electrical impulses in the heart and
○ can provide data about heart health.
● In certain kinds of heart disease, the heart’s self-pacing system fails to maintain a normal heart rhythm, and doctors can implant in the chest an artificial pacemaker, a device that emits electrical signals to trigger normal heartbeats.
23.6 What causes heart attacks?
● Heart muscle cells require nutrients and oxygen-rich blood to survive.
● Where blood exits the heart via the aorta, several coronary arteries immediately branch off to feed the heart muscle.
● A heart attack
○ is damage or death of cardiac muscle tissue and
○ usually results from a blocked coronary artery.
● More than half of all deaths in the United States are caused by cardiovascular disease—disorders of the heart and blood vessels.
● A stroke is the death of brain tissue due to the lack of O2 resulting from the rupture or blockage of arteries in the head.
● Arteries of most victims of a stroke or heart attack became impaired gradually by a chronic cardiovascular disease known as atherosclerosis.
● During the course of this disease, fatty deposits called plaques develop in the inner walls of arteries, narrowing the passages through which blood can flow.
● For more than 20 years, researchers have known that atherosclerosis and blood clot formation are associated with inflammation, the body’s general response to tissue damage. ○ Some researchers hypothesize that the body’s inflammatory response causes heart attacks.
○ Some studies show that certain anti-inflammatory drugs, such as aspirin, decrease the risk of heart attack.
○ However, aspirin is an anticlotting agent and an anti-inflammatory, so it is unclear which property makes it effective against heart attacks.
● Two large clinical trials to test the inflammation hypothesis were begun in 2013. ○ In these double-blind studies, members of the experimental groups are receiving drugs that specifically target inflammation.
○ The control group participants are given placebos.
○ Researchers will collect data on the occurrence of heart attacks, strokes, and other measures of cardiovascular health.
○ If blocking the inflammatory response proves to be an effective method of treating atherosclerosis, new approaches to treating cardiovascular disease could be developed that will save thousands of lives.
Structure and Function of Blood Vessels
23.7 The structure of blood vessels fits their functions
○ have thin walls consisting of a single layer of epithelial cells,
○ are narrow, about as wide as one red blood cell, and
○ exchange gas and fluid with the interstitial fluid.
● Arteries and veins
○ are lined by a single layer of epithelial cells and
○ have elastic fibers in an outer connective tissue layer that allows these vessels to recoil after stretching.
● Arteries contain a thick layer of smooth muscle in their walls that can constrict and reduce blood flow.
● Veins have one-way valves that restrict backward flow of blood.
23.8 Blood pressure and velocity reflect the structure and arrangement of blood vessels ● Blood pressure
○ is the force blood exerts on vessel walls,
○ depends on cardiac output and resistance of vessels to expansion, and
○ decreases as blood moves away from the heart.
● Blood pressure is
○ highest in arteries and
○ lowest in veins.
● Blood pressure is measured as
○ systolic pressure, caused by ventricular contraction, and
○ diastolic pressure, low pressure between contractions.
● How does blood travel against gravity, up legs?
○ Veins are squeezed by pressure from muscle contractions between two muscles or muscles and bone or skin.
○ One-way valves limit blood flow to one direction, toward the heart.
23.9 Measuring blood pressure can reveal cardiovascular problems
● A typical blood pressure for a healthy young adult is about 120/70.
● Blood pressure is commonly measured using a sphygmomanometer.
● Hypertension (high blood pressure) is a serious cardiovascular problem in which blood pressure is persistent at or above 140 systolic and/or 90 diastolic.
● Hypertension causes
○ the heart to work harder, weakening the heart over time,
○ increased plaque formation from tiny ruptures, and
○ increased risk of blood clot formation.
● Hypertension can contribute to
○ heart attacks,
○ strokes, and/or
○ kidney failure.
23.10 Smooth muscle controls the distribution of blood
● Smooth muscles in arteriole walls can influence blood pressure by changing the resistance to blood flow out of the arteries and into arterioles.
● Blood flow through capillaries is also restricted by precapillary sphincters.
● By opening and closing these precapillary sphincters, blood flow to particular regions can be increased or decreased.
● At any given time, only about 5–10% of your body’s capillaries have blood flowing through them.
23.11 Capillaries allow the transfer of substances through their walls
● Capillaries have very thin walls.
● Substances leave blood and enter interstitial fluid by
○ vesicles that form by endocytosis on one side of the cell and then release their contents by exocytosis on the other side, and
○ pressure-driven flow through clefts between epithelial cells.
● Blood pressure forces fluid out of capillaries at the arterial end.
● Osmotic pressure draws in fluid at the venous end, because the blood has a higher concentration of solutes than the interstitial fluid.
● Lost fluid is also picked up by the lymphatic system, which includes a network of tiny vessels intermingled among the capillaries.
Structure and Function of Blood
23.12 Blood consists of red and white blood cells suspended in plasma
● Blood consists of several types of cells suspended in a liquid called plasma, which ○ is about 90% water and
○ contains many different substances.
● Two classes of cells are suspended in blood plasma.
○ Red blood cells, or erythrocytes, transport O2 bound to hemoglobin.
○ White blood cells, or leukocytes, function inside and outside the circulatory system and fight infections.
■ Monocytes and neutrophils are white blood cells called phagocytes, which engulf and digest bacteria and debris from our own dead cells.
● Also suspended in plasma are platelets, cell fragments that are involved in the process of blood clotting.
23.13 Too few or too many red blood cells can be unhealthy
● Adequate numbers of red blood cells are essential for healthy body function. ● After circulating for three or four months, red blood cells are broken down and their molecules recycled.
● Much of the iron removed from the hemoglobin is returned to the bone marrow, where new red blood cells are formed at the amazing rate of 2 million per second.
● Anemia can be caused by
○ abnormally low amounts of hemoglobin or
○ a low number of red blood cells.
● Anemia causes fatigue due to lack of oxygen in tissues.
● The hormone erythropoietin (EPO) stimulates the bone marrow to produce more red blood cells.
● Some athletes artificially increase red blood cell production by
○ training at high altitudes,
○ injecting synthetic erythropoietin, and
○ blood doping in which blood is withdrawn, stored, and then reinjected just before a competition.
● Abuse of these methods can lead to clotting, stroke, heart failure, or even death.
23.14 Blood clots plug leaks when blood vessels are injured
● When a blood vessel is damaged,
○ platelets rapidly adhere to the exposed connective tissue and release chemicals that make nearby platelets sticky,
○ a cluster of sticky platelets forms a plug, and
○ clotting factors set off a chain of reactions that culminate in the formation of a reinforced patch, called a scab. In this complex process, an activated enzyme converts fibrinogen to a threadlike protein called fibrin.
■ Threads of fibrin reinforce the plug, forming a fibrin clot.
● Within an hour after a fibrin clot forms, the platelets contract, pulling the torn edges closer together.
● Chemicals released by platelets also stimulate cell division in smooth muscle and connective tissue, initiating the healing process.
23.15 Stem cells offer a potential cure for blood cell diseases
● The red marrow inside bones is a spongy tissue in which unspecialized stem cells differentiate into blood cells.
● When a stem cell divides,
○ one daughter cell remains a stem cell and
○ the other can take on a specialized function.
● Stem cells in bone marrow can differentiate into two main types of stem cells: ○ Lymphoid stem cells, which can then produce two types of lymphocytes, which function in the immune system.
○ Myeloid stem cells, which can differentiate into
■ other white blood cells, and
○ is cancer of white blood cells (leukocytes),
○ results in extra leukocytes that do not function properly, and
○ is usually fatal unless treated.
● Leukemia may be treated by
○ chemotherapy, or
○ the replacement of cancerous bone marrow with healthy bone marrow.
Questions & Answers
● Describe the general functions of a circulatory system.
○ These are the main roles of the circulatory system. The heart, blood and blood vessels work together to service the cells of the body. Using the network of arteries, veins and capillaries, blood carries carbon dioxide to the lungs (for exhalation) and picks up oxygen.
● Compare the structures and functions of gastrovascular cavities, open circulatory systems, and closed circulatory systems.
○ The gastrovascular cavity is a structure found in primitive animal phyla. It is responsible for both the digestion of food and the transport of nutrients throughout the body. The cavity has only one opening to the environment.
○ Open circulatory systems (evolved in crustaceans, insects, mollusks and other invertebrates) pump blood into a hemocoel with the blood diffusing back to the circulatory system between cells. Blood is pumped by a heart into the body cavities, where tissues are surrounded by the blood.
○ In a closed circulatory system, blood is always contained within vessels (arteries, veins, capillaries, or the heart itself).
● Compare the cardiovascular systems of a fish, an amphibian, a reptile, a bird, and a mammal. ○ The Cardiovascular System in Fish. A fish's cardiovascular system comprises of two main parts: the heart and the system of pipes (veins, arteries and capillaries) that carry blood throughout the body. Every organ and cell in the fish's body is connected to this system, which serves a wide variety of purposes.
○ The frog heart has 3 chambers: two atria and a single ventricle. The atrium receives deoxygenated blood from the blood vessels (veins) that drain the various organs of the body. The left atrium receives oxygenated blood from the lungs and skin (which also serves as a gas exchange organ in most amphibians).
○ The three-chambered reptilian heart is composed of two atria, which receive blood from the lungs and body, and a large ventricle, which pumps blood into arteries. Snakes and other reptiles have an interesting adaptation to their cardiovascular system that mammals lack.
○ A bird's circulatory system consists of a four-chambered heart and blood vessels. With each beat, or stroke, of the heart, a large volume of blood is carried throughout the bird's body by vessels called arteries. Blood is then returned to the heart by vessels called veins.
○ By circulating blood throughout the body, the cardiovascular system functions to supply the tissues with oxygen and nutrients, while removing carbon dioxide and other metabolic wastes. (mammals)
● Describe the pathway of blood through the mammalian cardiovascular system. ○ Blood drains from the superior vena cava (from the head and arms) or inferior vena cava (from the lower trunk and legs) into the right atrium,
○ Moves out to the lungs via the pulmonary artery,
○ Returns to the left atrium through the pulmonary vein, and
○ Leaves the heart through the aorta.
● Distinguish between diastole and systole.
○ During diastole, blood flows from veins to heart chambers
○ During systole, (contraction phase) blood flows from atria into ventricles to large arteries
● Explain how heartbeats are controlled.
○ The SA (sinoatrial) node generates electrical signals in atria and sets the rate of heart contractions.
○ The AV (atrioventricular) node relays these signals to the ventricles and causes ventricular contraction
■ Signals from the SA node spread through the atria.
■ Signals are delayed at the AV node. (0.1 sec)
■ Specialized muscle fibers pass signals to the heart apex.
■ Signals spread throughout the ventricles.
● Define a heart attack and cardiovascular disease.
○ A heart attack is the damage or death of cardiac muscle and usually results from a blocked coronary artery
○ Cardiovascular diseases are disorders of the heart and blood vessels.
■ A stroke (death of brain tissue from blocked or ruptured arteries in the head) and atherosclerosis (in which fatty deposits in the walls of arteries narrow the blood vessels and restrict blood flow)
● Relate the structure of blood vessels to their function.
○ Capillaries have thin walls, single layer of epithelial cells, are narrow, about as wide as one red blood cell, and increase surface area for gas and fluid exchange with the interstitial fluid.
○ Arteries and veins are lined by a single layer of epithelial cells and have elastic fibers in an outer connective tissue layer that allows these vessels to recoil after stretching. ■ Arteries contain a thick layer of smooth muscle in their walls that can constrict and reduce blood flow.
■ Veins have one-way valves that restrict backward flow of blood.
● Explain how and why blood pressure changes as blood moves away from the heart. ○ As larger arteries divide into smaller and more numerous arterioles, the total combined cross sectional area of the many vessels is much greater that the diameter of the one artery that feeds into them.
○ If there were only one arteriole per artery, the blood would actually flow faster through the arteriole. But it's like taking the nozzle off of a hose.
○ The velocity of blood is slowest through the capillaries due to the fact that it enhances the exchange of substances through body cells.
○ Pressure drops to near zero when it reaches the veins since it has passed through so much.
● Explain how blood is moved back to the heart.
○ Whenever the body moves, muscles squeeze blood through the veins which are often sandwiched between skeletal muscles.
○ One way valves allow the blood to flow only toward the heart. Breathing also helps return blood to the heart.
● Explain how blood pressure is measured. Give examples of normal and high blood pressure readings.
○ Blood pressure is measured as
■ systolic pressure—caused by ventricular contraction, and
■ diastolic pressure—low pressure between contractions.
● commonly measured using a sphygmomanometer.
○ healthy is 120/70.
○ unhealthy (hypertension) 140 systolic and/or 90 diastolic.
● Explain how blood flow through capillaries is regulated.
● Explain how the structure of a capillary relates to its functions.
○ Capillaries have very thin walls.
○ Substances leave blood and enter interstitial fluid by diffusion and pressure-driven flow through clefts between epithelial cells.
○ Blood pressure forces fluid out of capillaries at the arterial end.
○ Osmotic pressure draws in fluid at the venous end.
● Describe the components of blood and their functions.
○ Blood is a specialized body fluid. It has four main components: plasma, red blood cells, white blood cells, and platelets. Blood has many different functions, including: transporting oxygen and nutrients to the lungs and tissues.
● Describe the structure, function, and production of red blood cells.
○ Erythrocytes - red blood cells, Formed elements. Biconcave, lack nuclei and most organelles, filled with hemoglobin.
○ Biconcave - Large surface area ratio, Enables RBC's to form stacks that flow through narrow blood vessels (Rouleau)
○ Enables RBC's to flex, using spectrin protein
○ Hematopoiesis -Blood formation, occurs in the red bone, starts with hemocytoblast Begins with hemocytoblast, then reticulocytes and finally erythrocytes.
○ Erythropoietin (EPO) - hormone that controls the production of erythrocytes. ○ Erythropoietin is made via hypoxia. 3 million/sec
● Describe the process of blood clotting.
○ The immediate process of stopping bleeding after injury is known as hemostasis and involves three events which are: blood vessel spasm, the formation of the platelet plug and the blood clot formation process; known as blood coagulation.
○ Clotting of the blood occurs only when thrombin converts fibrinogen to fibrin clot. ● Define leukemia and describe the most common forms of treatment.
○ Leukemia is cancer of the body's blood-forming tissues, including the bone marrow and the lymphatic system.
○ But in people with leukemia, the bone marrow produces abnormal white blood cells, which don't function properly.
○ Treatment for leukemia can be complex — depending on the type of leukemia and other factors.
Control of Body Temperature and Water Balance
● During the Antarctic winter, male emperor penguins go approximately 110 days without nourishment while they
○ incubate eggs that must be kept above 35°C and
○ survive Antarctic temperatures as low as –50°C
● Most animals can survive fluctuations in the external environment because of homeostatic control mechanisms that keep their internal temperature and water levels within an optimal range.
25.1 An animal’s regulation of body temperature helps maintain homeostasis
● Thermoregulation is the homeostatic mechanism by which animals maintain an internal temperature within an optimal range despite variation in external temperature.
● Endotherms derive body heat mainly from their metabolism.
● Ectotherms absorb heat from their surroundings.
● Heat exchange with the environment occurs by conduction, convection, radiation, and evaporation
● Checkpoint question: If you are sweating on a hot day and turn a fan on yourself, what two mechanisms contribute to your cooling?
○ Evaporation (of sweat) and convection (fan moving air)
25.2 Thermoregulation involves adaptations that balance heat gain and loss
● Endotherms and many ectotherms maintain a fairly constant internal temperature within an optimal range despite external temperature fluctuations.
● Adaptations for thermoregulation include
○ the ability to adjust metabolic heat production,
○ circulatory adaptations,
○ evaporative cooling, and
○ behavioral responses
25.3 Coordinated waves of movement in huddles help penguins thermoregulate ● Scientists observing these huddles have wondered if each penguin has access to the center. ○ One hypothesis is that huddles are static—a penguin on the periphery of a huddle remains there.
○ An alternative hypothesis is that huddles are changing—a penguin on the periphery can eventually find itself in the center of a huddle.
○ These two hypotheses were tested with field observations, rather than experiments in a laboratory.
● A German study in 2011 used time-lapse photography and tracked individual birds. ● The study supports the hypothesis that huddles rearrange, allowing all penguins time in the warmest parts of these masses.
Osmoregulation and Excretion
25.4 Animals balance their levels of water and solutes through osmoregulation ● Osmoconformers have body fluids with a solute concentration equal to that of the surroundings.
● Osmoregulators have internal solute concentrations that are independent from those of the external environment.
● Through the process of osmoregulation, animals control the concentrations of solutes in their cells and bodies and prevent the excessive uptake or loss of water.
25.5 Several ways to dispose of nitrogenous wastes have evolved in animals
● Excretion is the disposal of toxic nitrogenous wastes.
● Ammonia (NH3) is poisonous but soluble and is easily disposed of by aquatic animals. ● Urea and uric acid are less toxic and easier to store but require significant energy to produce.
● Unlike ammonia and urea, uric acid is a water-insoluble precipitate, and thus water is not used to dilute it.
25.6 The urinary system plays several major roles in homeostasis
● The urinary system plays a central role in homeostasis, forming and excreting urine while regulating the amount of water and solutes in body fluids.
● Nephrons extract a filtrate from the blood and refine it into urine.
○ In filtration, blood pressure forces water and many small solutes into the nephron. ○ In reabsorption, water and valuable solutes are reclaimed from the filtrate. ○ In secretion, excess H+ and toxins are added to the filtrate.
○ In excretion, urine leaves the kidneys via the ureters, is stored in the urinary bladder, and is expelled through the urethra.
25.7 The kidney is a water-conserving organ
● The majority of water in the filtrate is reabsorbed in the proximal tubule.
● Further water conservation occurs because of a solute concentration gradient in the interstitial fluid.
25.8 Hormones regulate the urinary system
● Homeostasis is maintained through a change in the levels of hormones that act on the kidney’s collecting ducts.
● Antidiuretic hormone (ADH) is one hormone that regulates the amount of water excreted by the kidneys.
○ Signaling nephrons to reabsorb water from the filtrate, returning it to the blood and, ○ Decreasing the amount of water excreted
○ Inhibit the release of ADH and
○ Include alcohol and caffeine
25.9 Kidney dialysis can save lives
● Kidney failure can result from
○ diabetes, or
○ prolonged use of common drugs, including alcohol.
● A dialysis machine removes wastes from blood and maintains solute concentration. Questions & Answers
● Describe four ways that heat is gained or lost by an animal.
○ Convection- Transfer of heat from one place of another by the movement of others. ○ Radiation- Sunlight or heat source.
○ Evaporation- Liquid into gas.
○ Conduction- Spread through a substance when fast atoms glide with slow ones. ● Describe five categories of adaptations that help animals thermoregulate. ○ Increased metabolic production- ex. shivering.
○ Insulation- ex. hair.
○ Circulatory adaptation- ex. increased or decreased blood flow.
○ Evaporation cooling- ex. sweating.
○ Behavioral responses- ex. moving into the sun to get warmer.
● Compare the osmoregulatory problems of saltwater fish, freshwater fish, and terrestrial animals. ○ Freshwater fish: moving to keep water on their gills because there is no current ○ Saltwater fish: regulate PH with the salt content they intake
● Compare the three ways that animals eliminate nitrogenous wastes.
○ Ammonia through pee, Urea, Uric acid
■ ex. bird poop
● Describe the structure and functions of the human kidney.
○ The kidneys are two bean-shaped organs that extract waste from blood, balance body fluids, form urine, and aid in other important functions of the body.
○ They reside against the back muscles in the upper abdominal cavity.
○ They sit opposite each other on either side of the spine.
● Explain how the kidney promotes homeostasis.
○ Expels waste, regulates water balance, regulates ion balance.
● Explain how kidney filtrate is formed.
○ Glomerular filtration is the first step in urine formation and constitutes the basic physiologic function of the kidneys.
○ It describes the process of blood filtration in the kidney, in which fluid, ions, glucose, and waste products are removed from the glomerular capillaries.
● Describe the key events in the conversion of filtrate into urine.
○ Reabsorption removes nutrients, salt, and water for the urine.
● Explain how antidiuretic hormone contributes to homeostasis.
○ Antidiuretic hormone acts to maintain blood pressure, blood volume and tissue water content by controlling the amount of water.
● Explain why a dialysis machine is necessary and how it works.
○ The dialysis machine mixes and monitors the dialysate. Dialysate is the fluid that helps remove the unwanted waste products from your blood.
○ It also helps get your electrolytes and minerals to their proper levels in your body. ○ The machine also monitors the flow of your blood while it is outside of your body.