Bio 225 Circulation, Gas Exchange, Thermal Physiology

red blood cells v white blood cells

-Red blood cells, or erythrocytes (erythro- = "red"; - cyte = "cell"), deliver oxygen to cells. In mammals, red blood cells are small biconcave cells that at maturity do not contain a nucleus or mitochondria. In birds and non-avian reptiles, a nucleus is still maintained in red blood cells -The red coloring of blood comes from the iron-containing protein hemoglobin. This protein carries oxygen but it also transport carbon dioxide as well. -In mammals, the lack of organelles in erythrocytes leaves more room for the hemoglobin molecules and the lack of mitochondria also prevents the use of the oxygen for metabolic respiration. -Only mammals have nucleated red blood cells. The advantage of nucleated red blood cells that have other mammals, for instance camels, is that this cells can undergo mitosis. -nucleated red blood cells metabolize anaerobically without oxygen, making use of a primitive metabolic pathway to produce ATP and increase the efficiency of oxygen transport. -But not all organisms use hemoglobin as a method of oxygen transport. Invertebrates that utilized hemolymph rather than blood, use different pigments to bind to the oxygen. For example, hemocyanin, a blue-green corporate containing protein, is found in molluscs, crustaceans, and some of the anthropods. -White blood cells, also called leukocytes (leuko = white), make up approximately one percent by volume of the cells in blood. They are primarily involved in the immune response to identify and target pathogens, such as invading bacteria, viruses, and other foreign organisms. -WBCs are formed continually; some only live for hours or days, but some live for years. -WBCs have nuclei and do not contain hemoglobin and the different types of white blood cells are identified by their microscopic appearance after histologic staining and each has a different specialized function Two main WBC groups: 1. Granulocytes, which include the neutrophils, eosinophils, and basophils, and 2. the Agranulocytes which include the monocytes and lymphocytes. -Lymphocytes are the primary cells of the immune system, and include the B cells, T cells, and natural killer cells. B-cells destroy bacteria and inactivate their toxins. They also produce antibodies. T cells attack viruses, fungi, some bacteria, transplanted cells, and cancer cells. T cells attack the viruses releasing the toxines that kill the viruses. The natural killer cells attack a variety of infectious microbes and certain tumour cells.

plasma

-The liquid component of blood is called plasma, and it is separated by. The blood cells and platelets are separated by centrifugal forces to the bottom of a specimen tube. The upper liquid layer, the plasma, consists of 90 percent water. The plasma also contains the coagulation factors and antibodies. -also contains various substances required for the maintenance of the pH body, and osmotic load, and for protecting the bdody. The plasma also contains the coagulation factors and antibodies. -The plasma component of blood without the coagulation factors is called the serum.

LUNG, PLEURA, and CHEST WALL

-The lungs are pyramid-shaped, paired organs that are connected to the trachea by the right and left bronchi-The lungs are enclosed by the pleurae (pleura in singular) -The pleurae perform two: They produce pleural fluid and create a division between major organs that prevents interference due to the movement of the organs-The pleural sac consists of two layers of cells with a small amount of fluid between them -In a healthy person, the pleural pressure remains negative relative to atmospheric pressure throughout the entire respiratory cycle. This is called the transpulmonary pressure. -If the pleural sac is punctured, it causes a pneumothorax During pneumothorax, the pulmonary alveoli or airway becomes connected to pleural cavity and air migrates from the alveoli to the pleural cavity until the pressures of both areas are in equilibrium. The small airways and alveoli collapse and this condition causes trouble to breathe because the alveoli is no longer efficient in the gas-exchange process.

MECHANISMS of FROG RESPIRATION

1. Gills- The gills filter oxygen from the water and dispose of respiratory waste products. Upon maturation from a tadpole into a frog, these gills are lost. 2. Cutaneous Respiration- The skin of many frogs is thin and highly vascular to allow for gas exchange. Cutaneous respiration also allows for the frog to remain almost completely submerged under water for long periods of time, while still oxygenating their blood. 3. Buccopharyngeal Membrane- Frogs can also have gas exchange across the thin, highly vascular buccopharyngeal membrane, a lining along the mouth. -This type of respiration, can only occur while the frog is not submerged in the water and as it requires opening of the mouth. 4. Lungs- Postive Pressure Breathing- Many frogs use lungs to respire, bringing in air through their nares and mouth, into the trachea and then to the lungs for gas exchange and uptake of oxygen. However, frogs lack the diaphragm that is an anatomical structure present in many other species. Because they lack this feature, frogs use positive pressure breathing and must actively push air into their lungs.

Order for the sequence of the blood vessels that blood would travel in the systemic circuit, starting at the aorta? 1. venules 2.arterioles 3. capillaries 4. elastic arteries 5. medium veins 6. large veins 7. muscular arteries

4,7,2,3,1.5,6

Sponge Circulatory System

-Animals such sponge lack a circulatory system that transports internal fluid, but they have mechanisms to propel fluids around their bodies. -the sponge body is full of pores that opens into the spongocoel cavity. The water goes inside through the pores. -Cnidarians use muscular contraction to propel the water in their mouth and the Plathelminths contract the muscular pharynx to get the fluid through the gastrovascular cavity.

ALVEOLI

-Epithelial cells secrete pulmonary surfactant which is a mixture of lipids andproteins -Type II alveolar cells secrete pulmonary surfactant which is a mixture of lipids and proteins -The main function of surfactant is to lower the surface tension at the air/liquid interface within the alveoli of the lung

respiratory systems in mollusks

All mollusks breathe by gills that they are called the ctenidia because of their comb-like shape. An organ that is found exclusively mollusk is the mantle. The mantle is a soft tissue a layer of soft tissue that is formed from folds of the dorsal body walls. It lies beneath the shell where it covers the body of the animal. The mantle has several critical functions, one of them is the formation of this cavity, the mantle cavity where are the gills.

Aneurism

An aneurysm occurs when an artery's wall weakens and causes and abnormally large bulge, this bulge can rupture and cause an internal bleeding. Although an aneurysm can occur in any part of your body, there most common in the brain, aorta, or in the legs. Aneurysm has a variety of causes including high blood pressure and atherosclerosis, trauma, and heredity. The wall tension is creating a bulge, and if this is sustained is going to result in an aneurysm.

arteries, capillaries, veins,

Arteries are the specialized tubes which take the blood away from the heart, and the veins are dedicated vessels which bring back the blood from all parts of the body to the heart. The pumping organ (heart) pumps the blood. Arteries take the blood from the heart the blood from the heart and carry it to the tissues. For the exchange of materials between blood and tissues, arteries divide and subdivide into very tiny and fine branches called capillaries. These one-celled thick capillaries exchange nutrients between blood and tissues. The capillaries join and form bigger blood vessels called venules. These venules, them form veins which in the end bring blood back to the heart.

role of blood

Blood helps maintain homeostasis by stabilizing pH, temperature, osmotic pressure, and by eliminating excess heat. Blood supports growth by distributing nutrients and hormones, and by removing waste. Blood plays a protective role by transporting clotting factors and platelets to prevent blood loss and transporting the disease-fighting agent or white blood cells to the site of the infection.

action of epinephrine in cardiac cell

Both norepinephrine and epinephrine can increase contractility. The receptors for these molecules are beta-1 adrenergic receptors in the cardiomyocytes. After binding, adenylate cyclase is activated, and mediates a signal transduction pathway with the goal of phosphorylate several proteins to increase the rate and strength of contraction, as we can see here, by allowing calcium entry into the cytoplasm.

Pacemaker cells

Cells with the fastest intrinsic rhythms are called the pacemaker cells, because the contraction of the entire heart is determine by them. In vertebrates are usually located in the right atrium and Vena Cava, termed sinoatrial node, near the junction between these structures. Pacemaker cells initiate the heartbeat. Electrical activity initiated in the pacemaker spreads over the muscle of the two atria and then, after a slight delay, to the muscles of the ventricles. And this point, electrical activity is conducted rapidly through the atrioventricular bundle to the apex of the ventricle, and then continues through specialized fibers (Purkinje fibers) up the walls of the ventricles. This arrangement allows the contraction to begin at the apex or tip of the ventricles and spread upward, to squeeze to squeeze out the blood in the most efficient way. It also ensures that both ventricles contract simultaneously. Pacemaker cells have an unstable resting potential called pacemaker potential around -60mV and reaches a threshold abound -40mV and initiates an action potential. Non-selective cation channels open, (they are called funny because the unusual behavior of the current that is also called funny current) and this opening increases the permeability of the membrane to sodium, which causes the membrane potential to increase. As the membrane reaches the threshold, L-type calcium channels open and trigger the action potential. After 200 milliseconds, these channels close and potassium channels open repolarizing the cell and the cycle begins again. The membrane potential in a pacemaker cell which initiates the heartbeat.

Types of pumping structures

Chambered hearts are found in both vertebrates and invertebrates with different degree of complexity. In the case of muscular contractions of the heart, this increases the pressure within the heart chambers, when the pressure in the heart is higher than in the rest of the body, blood flows down this pressure gradient into the circulatory system. Contractile chamber such as the vertebrate heart that increases the flood pressure contracting the muscular walls. The pressure increases and the valve opens. One-way valve: the skeletal muscle acts as a pump; contraction and relaxation of the muscle compress and expands the blood vessel. Ex) The leg muscles that helps to push blood back to the heart Peristaltic contraction: the embryonic heart is seen as a pulsating blood vessel. Despite the absence of valves, this tubular heart generates unidirectional blood flow. Ex) The human heart starts beating around the 21st embryonic day, and during the initial phase of its pumping action, the embryonic heart is seen as a pulsating blood vessel. Despite the absence of valves, this tubular heart generates unidirectional blood flow.

regulation of ventilation in mammals

Chemoreceptors detect changes in CO2, hydrogen and O2 and send afferent sensory information to the brain. In the brain the information is integrated and provides input to the respiratory rhythm generators to modify the rate or depth of breathing. These changes in breathing act by negative feedback to maintain blood co2 and o2 levels within a narrow range.

compliance

Compliance is the ability of any compartment to expand to accommodate increased content. A metal pipe is not compliant, whereas a balloon it is. The greater the compliance of an artery the more effectively it is able to expand to accommodate surges in blood flow without increased resistance or blood-pressure. Veins are more compliant than arteries and can expand to hold more blood. When vascular disease causes stiffening of arteries, compliance is reduced and resistance to blood flow is increased. The result is more turbulence, higher pressure within the vessel, and reduced blood flow. This increases the work of the heart.

Effects of damage to cells

Damage to cells can trigger one of two opposing responses: 1. apoptosis (a form of cell death) and 2. the heat shock or stress response that prevents damage or facilitates recovery to maintain cell survival. Heat shock proteins are chaperones (this is a protein that helps in the folding or unfolding of other molecules). Many cells exposed to extreme temperatures undergo a heat shock response that leads to an increase in the levels of a specific protein that help in cell repair, as we can see in the figure, like the heat shock protein 70, HSp70. During a heat shock, the cell starts synthesizing certain proteins that help repair the damaged proteins. These proteins are crucial for ectothermic animals to survive brief periods of extreme temperature that often occur within their natural environment.

types of blood vessels: arteries v veins

Different types of blood vessels vary slightly in their structures, but they share the same general features. Arteries and arterioles have thicker walls than veins and venules because they are closer to the heart and receive blood that is surging at a far greater pressure. Each type of vessel has a lumen, a hollow passageway through which blood flows. Arteries has smaller lumens than veins, a characteristic that helps to maintain the pressure of blood moving through the system. Together, their thicker walls and smaller diameters give arterial lumens a more rounded appearance in cross section than the lumens of veins.

RESPIRATORY SYSTEM in ECHINODERMS

Echinoderms have diverse respiratory structures, many of them use their tube-feed for gas exchange. The thin walls of their tube-feed allow oxygen to diffuse in and wastes to diffuse out. Sea stars also have external gill structures called respiratory papulae, that they are scattered across the body surface.

Ventilation

Eupnea apnea hyperpnea tachypnea DYSPNEA hyperventilation hypoventilation

Animals have the ability to tolerate changing temperatures

Eurytherm animals can tolerate a wide range of ambient temperature, and a stenotherm animal can just tolerate a narrow range of ambient temperature. These categories are valid for either ecto or endotherms. The range of tolerance is the difference between the incipient upper lethal temperature of IULT, and the incipient lower temperature of ILLT as we can see in the figure. The ability to tolerate temperature changes with thermal history for both ectotherms and poikilotherms, in other words, many animals can remodel their tissues and systems to alter their sensitivity to the temperature, either through thermal acclimation, or through seasonal changes (seasonal acclimatization) in order to cope better with the temperature. In this figure we can see the impact of thermal history. (Acclimation is the coordinated phenotypic response developed by the animal to a specific stressor in the environment while acclimatization refers to the coordinated response to several individual stressors simultaneously, e.g., temperature, humidity, and photoperiod).

short term cooling

Even though homeotherms regulate their body temperatures around a specific set point, the body temperature of most homeotherms is not completely uniform. Heterothermy describes variations in body temperature along both spatial and temporal scales. For example, animal body temperature is usually warmest at the core but may be much lower in the extremities. The extremities are usually allowed to cool in homeotherms, while the body core temperature can be conserved by warming the blood returning from the extremities through counter-current exchange. In jackrabbits, the ears are allowed to warm above core body temperature, in order to facilitate body heat dissipation by radiation. The heterothermy benefits both ecto- and endotherms: It allows an endotherm to conserve energy in cold temperatures reducing the costs of thermoregulation, and allows an ectotherm having a period of accelerated metabolism to speed digestion, nutrient assimilation, and biosynthesis. In this graph, we can see that birds can undergo dramatic and prolonged changes in body temperature when exposed to cold temperatures at nighttime and their body temperature decreases by several degrees. Although these animals are allow to have low body temperatures, still is higher than the ambient temperature so this is why they are considered homeotherms, and they are called, temporal heterotherms (example: hibernating mammals). Other homeotherms may temporarily use fever in response to pathogen presence. A special case of temporal heterothermy involves animals that not only adjust their body temperature but also adjust their metabolic rates. Regional heterotherms are those animals that lose their metabolic heat to the environment, and cannot elevate their body temperature much above the ambient temperature, so they have to retain heat in certain regions of the boy. Some fish like swordfish are ectotherms but can warm specific parts of their bodies.

Resistors in series and parallel

Fluids flow down pressure gradients, and resistance due to friction opposes this movement, the radius of a tube affects its resistance, and the resistance of a vessel determines the flow. Circulatory systems are similar to electrical circuits; like electrical resistors, blood vessels can be arranged in series or in parallel. The total resistance of a circuit, with resistors arranged in series is the sum of the individual resistances: Rt=R1+R2... However, when resistors are arranged in parallel, the total resistance is determined using this equation: 1/Rt=1/R1+1/R2... In this case, the total flow through each point of a circuit is equal, but the flow is divided among the resistors distributed in parallel.

Most carbon dioxide travels in the blood as: CO2 H2CO3 CH4 HCO3- CO

HCO3-

hemocytes of insects and vertebrates

Hemocytes are the cells found in the circulatory fluid of many animals. They are responsible for oxygen transport, storage, nutrient transport, phagocytosis of damaged cells, immune defense. Hemocytes of invertebrates: In insects, the main cells are: plasmotocytes, that are small cells that use phagocytosis to eliminate foreign cells or particles. -lamellocytes- cells produced in response to parasitic infections, and the crystal cells that contain enzymes and lysate foreign particles. hemocytes of vertebrates: -erytrocytes (this is the cell containing hemoglobin) -leukocytes are immune cells that develop specific immunity, and we have different type of leucocytes, they are:, the lymphocytes, monocytes, macrophages, granulocytes, and thrombocytes. Monocytes and macrophages engulf and destroy invading particles. Thrombocytes are involved in blood clotting, in mammals the most important ones are the platelets.

Blood and hemolymph

Hemolymph is the circulating fluid of open circulatory system. It moves through the open circulatory system, directly bathing the organs and tissues. The main component of hemolymph is water, which functions as a solvent for a variety of molecules. Insect hemolymph differs substantially from vertebrate blood with the absence of erythrocytes, and a high concentration of the amino acids being two of the common distinguishing features. Hemolymph serves as a water storage pool for use by tissues during desiccation and as storage depot but for other types of chemicals. It also contains circulating cells. In many invertebrates, the proteins in the in the hemolymph are mostly respiratory pigments that are used to transport or store oxygen. The major difference between insect blood and the blood of vertebrates, including humans, is that vertebrate blood contains red blood cells. Hemolymph is mostly water, but it also contains ions, carbohydrates, lipids, glycerol, amino acids, hormones, some cells and pigments -Blood and hemolymph have proteins -Blood and hemolymph contain cells: hemocytes

An electrocardiogram can tell us different things

How fast is the heartbeat, (the numbers of beats per minute) and a normal cardiac reading is called a sinus rhythm because the heartbeat is determined by the sinoatrial node. The P wave associated is between 0.12 seconds, and 0.22 seconds (this is a normal speed of conduction). Abnormal rhythms (arrhythmia), can be caused by different problems with the cardiac conduction system, the atrial fibrillation is characterized by a disturbed conduction through the atrium, so the atria contract in a uncontrolled fashion. There is not a clear P wave, the rhythm is irregular, and the R-R intervals are variable. It is not usually dangerous as long as the ventricular contraction stays normal. In contrast, we have the ventricular fibrillation, which is an uncoordinated contraction of the ventricles, and is potentially deadly because the pumping of blood to the tissues is ineffective leaving to oxygen deprivation in the tissues and if this affects the brain is going to be fatal. it appears as random waves, as we can see in C in the electrocardiogram with not recognizable QRS complex. In this case, an electronic defibrillation delivers an intense pulse of the current to the body, and all cells of the heart depolarize simultaneously. So the pacemaker cells are able to initiate a normal heartbeat since they are going to be the first to depolarize after the defibrillation. But if the pacemakers are already damaged, defibrillation won't be effective. In the case of atrioventricular blocks, this condition occurs when transmission of electrical signals from the atria to the ventricles is impaired. There are some degrees of this condition, and the third degree is the most serious one. And it's characterized by lack of association between the P wave and the QRS complex, if not treated, can lead to ventricular fibrillation, and it can be treated with artificial peacemakers.

The response of lowland-adapted animals like humans, experiencing high-altitude hypoxia

Hypoxia a condition of underoxygenation, which is an inadequate level of tissue oxygenation for cellular metabolism In the high altitudes, low barometric pressure decreases partial pressure of oxygen in the alveolus. The syndrome of adaptive failure to chronic hypoxia is characterized by excessive erythrocytosis with abnormally high Hb and hematocrit levels, hypoventilation (because of increase CO2 in alveolus displaces oxygen), pulmonary hypertension, and eventually right heart failure

gas properties

Ideal Gas Law:The total pressure exerted by a gas is related to the number of moles of the gas and the volume of the chamber. PV=nRT Dalton's Law of partial pressures: In a gas mixture, each gas exerts its own partial pressure. Air is a mixture of gases, 78% nitrogen, 21% oxygen, 0.9 argon, and 0.03% carbon, carbon dioxide. Henry's Law: The amount of gas that will dissolve in a liquid is determined by the partial pressure of the gas and the solubility of the gas in the liquid.

breathing is also dependent upon the contraction and relaxation of muscle fibers of both the diaphragm and the thorax

In addition air pressure of the atmosphere, and the air pressure within the lungs. breathing is also dependent upon the contraction and relaxation of muscle fibers of both the diaphragm and the thorax. The lungs themselves are passive during breathing, meaning they are not involved in creating the movement that helps inspiration and expiration. This is because of the adhesive nature of the pleural fluid which allows the lungs to be pulled outward when the thoracic wall moves during inspiration. The recoil of the thoracic wall during expiration causes compression of the lungs. Contraction and relaxation of the diaphragm and intercostal muscles (found between the ribs) cause most of the pressure changes that result in inspiration and expiration. These muscle movement and subsequent pressure changes cause air to either rush in or be forced out of the lungs. So when the thoracic cavity expands, the diaphragm contracts, when the diaphragm relaxes, the thoracic cavity is reduced and the external intercostal muscles relax. This is during expiration.

futile cycles and thermogenesis

In metabolic processes heat arises as a by-product. Endotherms, for instance, use that heat from metabolic process. Endotherms have specific thermogenic ways with the main purpose of heat production, and these thermogenic pathways depends on futile cycling, in which chemical potential energy is spent to generate heat. Most of these cycles involve ATP synthesis and ATP hydrolysis in a cycle. In the figure we can see a summary of different futile cycles. A futile cycle occurs when two metabolic pathways run at the same time in opposite directions, without other effect than to dissipate energy in the form of heat (like glycolysis and gluconeogenesis) and appeared that is a cycled with no net utility for the organism, this is the reason is why is called futile. But later, research showed that the cycle may be used to maintain thermal homeostasis because generates heat rapidly. One example is the brown adipose tissue in young mammals.

RESPIRATORY SYSTEM in JAWLESS FISH

In the case of jawless fish, jawless fish like lampreys and hagfish, they have multiple pairs of gill socks located in the anterior part of their body. The elasmobranchs ventilate their branchial chambers by expanding the volume of the mouth. These increases in volume sucks fluid into the buccal cavity via the mout and the spiracles. They are a pair of nostril-like structures on the top of the head, the animal closes its mouth and spiracles and the muscles surrounding the buccal cavity contract, reducing the volume of the cavity, and forcing the water past the gills and out via the external gills. As the water passes over the gills, oxygen is absorbed into the blood across the thin skin of the gill surface and the CO2 moves into the water. In teleost fishes, the gills have evolved farther, all gills are protected by a commun operculum whereas in elasmobranchs, each gill slit was protected by an interbranchial septum. The operculum is a hard, plate-like, bony flap that covers the gills of a bony fish. The mechanism of the respiration include the flow of water through the mouth and oral valve and passage through the buccal and opercular chambers. In teleost fish, the gills are ventilated by a dual pump. The dual refers to the fact that there are really two pumps: a buccal and a parabranchial pump or opercular pump. This pump works in a fashion that produces an almost continuous unidirectional flow of water.

solubility of gases

In the cell environmental gases are much more soluble in lipids than they are in aqueous solution. When they partial pressures are at equilibrium, the same in the extracellular fluid outside the cell, in the membrane, and inside the cell, the concentration of gas will actually be higher in the membrane than outside the cell, because the gas has a higher solubility in the membrane lipids. Taking into account the properties of the gasses, at sea level and at 20 Celsius temperature, the concentration of oxygen is higher than the concentration of oxygen in the water.

albumin and globin

In the vertebrates, the principal proteins dissolved in the circulatory fluid are albumin, (this is the carrier protein) and globulins (they are involved in blood clotting).

Summary of vertebrate circulatory and cardiac anatomy

In vertebrates, the principal differences in blood vascular system involves the gradual separation of the heart into separate pumps, as vertebrates evolved from aquatic life with gills, breathing to fully terrestrial life with lung breathing. In the case of the fish, it's a single circuit circulatory system with the limitation in the amount of blood pressure that the dedicate gills can tolerate. Blood makes a single circuit through a fish vascular system; It is pumped from the heart to the gills where it's oxygenated, then flows into the dorsal aorta to be distributed to the body and finally, it returns by veins to the heart. In this circuit, the heart must provide sufficient pressure to push the blood through two sequential capillary systems, first of the gills, and then that of the remainder of the body. In amphibians has a different architecture of the circulatory system with the evolution of lung breathing and elimination of gills between the heart and aorta, vertebrates develop a high pressure double circulation. A systemic circuits that provides oxygenated blood to the capillary beds of the body organs and a pulmonary circuit that serves the lungs. The beginning of this major evolutionary change probably resembled the condition seen in lungfishes and amphibians. In modern amphibians (frogs, toads, and salamanders) the atrium is completely separated by a partition into two atria. The right atrium receives venous blood from the body, while the left atrium receives oxygenated blood from the lungs. >> The ventricle is undivided, but venous and arterial blood remain mostly separate by the arrangement of vessels leaving the heart. Separation of the ventricles is nearly complete in some reptiles like the crocodiles, and it's completely separate in birds and mammals. Systemic and pulmonary circuits are now separate circulations, each served by one half of a dual heart.

Myocyte stretching

Increased venous return increases the ventricular filling and therefore pre-load, which is the initial stretching of the cardiac myocyte prior contraction. Myocyte stretching increases the sarcomere length which causes an increase in force generation and enables the heart to eject the additional venous return, thereby increasing stroke volume. changes in sympathetic activity until the position of the curve, an increase in sympathetic activity shifts the curve upwards. The vascular smooth muscle cells that surround the arterioles are sensitive to the extracellular fluids conditions around them. T they contract or relax in response to changes in the concentration of oxygen, carbon dioxide, hydrogen, and potassium

The kidneys also play a role in the long-term regulation of the mean arterial pressure

Increasing the blood volume increases the blood pressure, and decreases in blood volume will lead to a decrease in blood pressure. The veins are compliant and act as a volume reservoir, but their capacity is limited. Therefore, the kidneys play a major role in maintaining blood volume. It is an important organ for the homeostatic regulation of blood pressure. changes in the arterial pressure can lead to changes in blood volume by altering kidney function. And changes in blood volume can lead to changes in arterial pressure.

the cardiac rhythm of just one cardiac cycle

Initially, both the atria and ventricles are relaxed in diastole, the P Wave represents depolarization of the atria and is followed by atrial contraction or systole. Atrial systole extends until the QRS complex, at which point, the atria relax. The QRS complex, represents depolarization of the ventricles and is followed by ventricular contraction. The T wave represents the repolarization of the ventricles and marks the beginning of ventricular relaxation. This is a summary of the electrocardiogram tracing and measures the millivolts versus time.

Arthropod respiratory system and discontinuous gas exchange cycle (DGC).

Insects take oxygen and expel carbon dioxide using a series of internal air tubes, the trachea. These pass fine branches, the tracheoles, to all parts of the body. The most extensive tracheal system is found in insects. The ends of the tracheoles are filled with circulatory fluid: hemolymph. Oxygen dissolves in this fluid and then diffuses across the thin walls of the tracheoles. The tracheoles go directly to the individual cells, and bringing them into close contact with the mitochondria of the cells. This results in a very low diffusion distance and enhances oxygen delivery. The respiratory system of an insect is very efficient for small organisms. As body size increases, the efficiency decreases. When body diameter exceeds about three centimeters, the respiratory needs cannot be met. Hence, it is the respiratory system of insects which restricts their body size. Many insects open and close their spiracle in a cyclic pattern. This is a discontinuous gas exchange cycle, or DGC. A typical discontinuous gas exchange cycle starts with a closed-spiracle phase, during which little external gas exchange takes place, followed by a fluttering-spiracle phase, which is usually dominated by diffusive oxygen uptake. The DGC is terminated by an open spiracle. This is the open phase during which accumulated CO2 escapes.

insect circulatory system

Insects, like all other arthropods, have an open circulatory system. -Hemolymph has direct contact with all internal tissues and organs. -The circulatory system is responsible for movement of nutrients, salts, hormones, and metabolic waster through the insect's body. -In addition, it plays several critical roles in defense. In some insects, the blood aids in thermoregulation. -A dorsal vessel is the major structural component of an insect's circulatory system. This tube runs longitudinally through the thorax and abdomen. In most insects, it is fragile, membranous structure that collects hemolymph in the abdomen and conducts it forward to the head. -In the abdomen, the dorsal vessel is called the heart. It is divided segmentally into chambers that are separated by valves to ensure one-way flow of the hemolymph.

Carbon dioxide equilibrium curve

MITOCHONDRIAL respiration produces carbon dioxide that must be transported out of the body. The carbon dioxide equilibrium curve, which shows the relation between the total carbon dioxide concentration of blood and the CO2 partial pressure, is a key tool for analyzing carbon dioxide transport. The blue line shows the total amount of CO2 in deoxygenated blood. The red line shows the total amount of CO2 in oxygenated blood and the green line shows the portion of that carbon dioxide dissolved in plasma. The Haldane effect, is an increase in the total carbon dioxide concentration of the blood caused by deoxygenation of the respiratory pigment. The Haldane effect aids carbon dioxide transport by promoting CO2 uptake by the blood in the systemic tissues and CO2 loss from the blood in the breathing organs. In b) we can see the CO2 transport in vertebrate blood. Most carbon dioxide carried in blood is typically in the form of bicarbonate, HCO3-. The extent of HCO3- formation depends on blood buffers and determines the shape of the carbon dioxide equilibrium curve. Because respiratory pigments are major blood buffers, they play major roles in carbon dioxide transport. Rapid uptake of CO2 by the blood or loss of CO2 from the blood requires the action of carbonic anhydrase, an enzyme localized to certain places (e.g., red blood cells).

physiologic cold response

Modest cooling of the skin below a temperature of 26 °C activates transient receptors in sensory neurons, which acts as a sensor for mild, non-noxious cold and mediates the sensation of cold to the central nervous system. The signals from the skin are integrated in the preoptic area (POA) of the hypothalamus together with temperature sensations from the brain and viscera. Sympathetic and somatic nervous system outflow from the POA stimulates shivering as well as non-shivering thermogenesis, thus pre-emptively counteracting cold ambient temperatures. (BAT= brown adipose tissue).

Ventilation of the respiratory surface

Most animals ventilate the respiratory surface moving the external medium by bulk flow. Ventilation of the respiratory surface improves the efficiency of gas exchange with the environment. In sponges, the beating of flagellated cells move water through a series of pores and into central cavity called spongocoel. This bulk flow moves the water through the animal cells. In the jellyfish and similar animals, muscle contractions play a role in the movement of water through the mouth into the gastro vascular cavity, which connects all parts of the body. As water passes the tissues, oxygen diffuses into cells.

reptilian lungs

Most reptiles have two lungs with the exception of some snakes. The lung ventilation, in reptiles like lizards is based on the intercostal muscles, in the use of the intercostal muscles, but in the case of turtles, the ribcage is fused to their rigid shell and can"t be moved to ventilate the lungs. So instead, these animals have abdominal muscles that expand and compress the lungs. Also, the movement of the limbs may assist in lung ventilation. In the case of crocodiles, they breath using the abdominal cavity mostly, through the hepatic septum, which is a sheet of connective tissue attached to the liver. The ventilation in birds is physically distinct from the mammalian respiratory system. The birds respiratory system consists of paired lungs which contain static structures with surface for gas exchange, and connected air sacs, which expand and contract causing air to move through the static lungs. Air sacs do not play a direct role in oxygen and carbon dioxides exchange, however, they do keep oxygen-rich air moving in one direction through the avian respiratory system. Birds do not have diaphragm, instead, air is moved in and out of the respiratory system through pressure changes in the air sacs. Unidirectional flow means that air moving through bird lungs, is largely fresh air and has a higher oxygen content, therefore, in bird lungs, more oxygen is available to diffuse into blood. This contrasts with mammalian lungs

Structure of vertebrate hearts: crocodilian reptiles

Most reptiles possess three chambered heart, with the exception of crocodilians. Reptiles are much less susceptible to the adverse effect of hypoxia and changes in blood pH, (hypoxia is low oxygen) and therefore, capable of enduring much wider fluctuation in heart rate, blood pressure, and oxygenation. The morphology of the reptilian heart results in the mixing of oxygenated and deoxygenated blood. They can bypass either the pulmonary or systemic circuit which is called the cardiac shunt, that also the amphibians have. (in birds and mammals, cardiac shunts are detrimental, but in reptiles this condition is often considered a derived trait, conveying important physiological functions, but alternative views are suggesting that in reptiles cardiac shunts represent either an ancestral condition or an embryonic trait.) Blood goes from the right atrium to the pulmonary artery under non-shunting conditions and from the left atrium to the aortas, both left and right aortas. When there is a shunt, the blood flow different paths. During the time the reptiles hold their breath, R-L shunt takes place (in the diving, for instance) in the case of crocodiles, the difference is that they have a four chambered heart that are completely divided by muscular septum, but the shunts are more limited than the other reptiles. In general, the magnitude of these shunts is affected by the ventilatory state and provides these animals with a flexibility in blood flow that cannot be achieved in mammals or birds.

factors influencing vasoconstriction and vasodilation

Neurological regulation of blood pressure and flow depends on the cardiovascular centers located in the medulla oblongata. This cluster of neurons response to changes in blood pressure as well as blood concentration of oxygen, carbondioxide, and hydrogen ions. There is also a small population of neurons that control vasodilation in the vessels of the brain and skeletal muscle by relaxing the smooth muscle fibres in the vessel tunics. Many of these are cholinergic neurons, they release acetylcholine, which in turn stimulates the vessels' endothelial cells to release nitric oxide, which causes vasodilation, others release norepinephrine that binds to Beta2 receptors and a few neurons release nitric oxide directly as a neurotransmitter. Endocrine control over the cardiovascular system involves the catecholamines: epinephrine, and norepinephrine, as well as several hormones that interact with the kidneys in the regulation of blood volumen. The catecholamines, epinephrine and norepinephrine are released by the adrenal gland and enhance and extend the body's sympathetic or "fight or flight" response. They increase heart rate and force contraction while temporarily constricting blood vessels to organs not essential for "fight or flight" and redirecting blood flow to the liver, muscles or heart. Related with the endocrine control, we have the antidiuretic hormone (ADH) vasopressin. Increasing osmolality prompts the hypothalamus to release vasopressin increasing osmolality of tissue fluid, usually in response to significant loss of blood volume. Vasopressin signals its target cells in the kidneys to reabsorb more water, as you already know, thus preventing the loss of additional fluid in the urine. This will increase overall fluid levels, and help restore blood volume and pressure. In addition, vasopressin constricts peripheral vessels. On the other hand, specialized cells in the kidneys found in the juxtaglomerular apparatus respond to decreased blood flow by secreting renin into the blood. Renin converts the plasma protein angiotensinogen, which is produced by the liver into its active form, which is angiotensin I. This angiotensin I circulates in the blood and is converted into angiotensin II in the lungs. This reaction is catalyzed by one enzyme; the angiotensin converting enzyme, (ACE). Angiotensin II is a powerful vasoconstrictor, greatly increasing blood pressure. Then also we have the atrial natriuretic hormone, secreted by cells in the atrial of the heart, is secreted when blood volume is high. Natriuretic hormones are antagonists to angiotensin II and they promote loss of sodium and water from the kidneys, and supress renin, aldosterone. and vasopressin production and release, all these actions promote loss of fluid from the body, so the blood volume and blood pressure drop. The vascular endothelium synthesizes the vasodilator and anti-aggregatory mediator nitric oxide from L-arginine. Increased nitric oxide causes vasodilation, increasing blood flow to the damaged areas. They've oxide is induced by histamine, bacteria, and substances associated with vascular endothelial damage. It plays an important role mediating inflammation. During exercise, nitric oxide is released in the arteries of skeletal muscle causing vasodilation. Also activates guanylate cyclase in the vascular smooth muscle and catalyze the conversion of GMP to cGMP, which triggers muscle relaxation.

Three homeostatic mechanisms ensure adequate blood flow, blood pressure, distribution, and ultimately perfusion

Neuronal, endocrine, and autorregulatory mechanisms

RESPIRATORY SYSTEM in SHARKS

On the other hand, ram ventilation is a strategy used by many fish species and is the production of respiratory flow in some fish in which the mouth is open during swimming, such that water flows through the mouth and across the gills. In fish which have a reduced or no ability to pump water buccally, such as mackerel or sharks, perpetual swimming is required to maintain ventilation. Ram ventilation is highly efficient because the fish doesn't use energy to ventilate their respiratory to the surface. The oxygen dissolves in water but at a lower concentration than in the atmosphere. The atmosphere has roughly 21% oxygen. In water, the oxygen concentration is much smaller than that, as we already learned. Gills are the thin tissue filaments that are highly branched and folded. When water passes over the gills, the dissolved oxygen in water rapidly diffuses across the gills into the bloodstream. Blood with a low concentration of oxygen molecules circulate through the gills. The concentration of oxygen molecules in water is higher than the concentration of oxygen molecules in gills, and as a result, oxygen molecules diffuse from water (where it is a high concentration) to blood, where is a low concentration. The gills in general, are highly vascularized and the number of gill filaments and lamellae (this is the basic structure of the gills) varies among fish species. More active species tend to have more lamellae and a larger surface area than the less active species. The pulmonated arachnids like scorpions, spiders, respire via book lungs, which are internalized gill-like organs with stacks of hemolymph-filled lamellae that facilitates gas exchange. Each book lung consists of a series of thin plates that they are highly vascular.

Types of circulatory systems: open and closed

Open Circulatory System 1. Blood isn't restricted to blood vessels. Blood is in direct contact with body tissues. 2. There are no characteristic blood. Hemolymph flows in sinuses of hemocoel 3. When blood is in direct contact with tissues, only then exchange of materials takes place. 4. System doesn't support transport of 5. This system can't maintain blood pressure. There is no respiratory pigment dissolved in blood. It is white. Closed Circulatory System 1. Blood is always restricted in blood vessels i.e. arteries, capillaries and veins. 2. There is a sophisticated and unified vessels. Haemolymph flows in sinuses of system of arteries, capillaries and veins. The sinuses are open spaces and haemolymph directly comes in contact with tissues and transport nutrients. This system only transports nutrients. Gases are not transported by this system, and the gasses are transported by the tracheal system. 3. Through capillaries, nutrients and waste materials are exchanged between tissues and blood by means of tissue fluid. 4. Not only nutrients are transported, gases. gases are also transported. 5. This system can maintain Blood Pressure. Haemoglobin, a respiratory pigment is present in blood.

Oxygen affinity and hemoglobin and allosteric regulation

Organic molecules and inorganic ions frequently serve as allosteric modulators of respiratory-pigment function. The compound 2,3 diphosphoglycerate 2,3-DPG (2,3-BPG) in the red blood cells of mammals, for example, chronically decreases the O2 affinity of the hemoglobin in the cells. It stabilizes the Hb molecule in its deoxygenated state and decreases affinity for O2Example, causes of increased 2,3 DPG include anemia, alkalosis, chronic hypoxemia Allosteric regulation, broadly speaking, is just any form of regulation where the regulatory molecule (an activator or inhibitor) binds to an enzyme someplace other than the active site. The place where the regulator binds is called the allosteric site.

mammalian heart function

Since the right side of the heart sends blood to the pulmonary circuit, it is smaller than the left side, which must send blood out to the whole body in the systemic circuit. It is divided into four chambers: Two atria and two ventricles. There is one atrium and one ventricle on the right side, and one atrium and one ventricle on the left side. The atria are the chambers that receive blood and the ventricles are the chambers pump blood. The right atrium receives deoxygenated blood from the superior vena cava, which drains blood from the jugular vein that comes from the brain, and from the veins that come from the arms, as well as from the inferior vena cava, which drains blood from the veins that come from the lowered organs and the legs. In addition, the right atrium receives blood from the coronary sinus, which drains deoxygenated blood from the heart itself. The deoxygenated blood then passes to the right ventricle through the atrioventricular valve or the tricuspid valve, a flap of connective tissue that opens in only one direction to prevent the backflow of blood. The valve separating the chambers on the left side of the heart valve is called bicuspid, or mitral valve. After it is filled, the right ventricle pumps the blood through the pulmonary arteries bypassing the semi-lunar valves (or pulmonic valve) to the lungs for reoxygenation. After blood passes through the pulmonary arteries, the right semilunar valves close, preventing the blood from flowing backwards into the right ventricle. The left atrium, then receive the oxygen-rich blood from the lungs via the pulmonary veins. This blood passes through the bicuspid valve (or mitral valve) to the left ventricle, where the blood is pumped out through aorta, the major artery of the body, taking oxygenated blood to the organs, and the muscles, the whole body. Once blood is pumped out of the left ventricle and into the aorta, the aortic semilunar valve (or aortic valve) closes preventing blood from flowing backward into the left ventricle. This pattern of pumping is referred to as double circulation and is found in all mammals.

Small animal circulation v large animal circulation

Small organisms lack circulatory systems, and rely on diffusion for molecule transport, this is rapid over short distances only. Direct diffusion through the body surface supplies the necessary gases and nutrients for small organisms. But even some single-celled protozoa have a rudimentary circulatory system. Larger animals can move fluids through their bodies in a process called "bulk flow" to transport substances across long distances, and allows the fluid to go from an area of high pressure to an area of lower pressure. Ex) one-way valves that ensure the unidirectional flow In the case of bulk flow, increased pressure in a blood vessel for instance, drives the flow in one direction. All animals use bulk flow of fluids in their circulatory system to transport substances, and allows the animal transport oxygen and nutrients and to remove carbon dioxide and wastes in a fast way. All circulatory systems use diverse pumping structures to move fluid around the system.

Mammalian heart structure

So we can see here through the superior vena cava and inferior vena cava, the blood that needs oxygen is going to enter to the right atrium the superior vena cava, is bringing the blood that needs oxygenation from the brain and also from the arms the inferior vena cava is bringing the blood from the lower parts of the body, including the legs. So no-oxygen blood comes to right atrium and it is going to be transferred to the right ventricle and from the ventricle is going to go to the pulmonary artery, to the lungs to get oxygen. On the other hand, when the blood is oxygenated in the lungs, the blood comes from the pulmonary veins to the left atrium, from the left atrium goes through the bicuspid valve, or atrioventricular valve, to the left ventricle, and from there is going to be pumped to the rest of the body through the aorta. the left ventricle has a bigger musculature, muscle is thicker than the right ventricle because the left ventricle has to pump the blood to the whole body but the right ventricle only has to pump the blood to the lungs

hypothalamus and thermoregulation

Temperatures are monitored peripherally and centrally by temperature-sensitive neurons. Related to the previous slide, we can see here how mammals regulate TA by peripheral cold-sensitive neurons located in the skin and the viscera. When TA decreases, hypothalamus receive signals from peripheral neurons. The temperature of the central nervous system must be more stable than the temperature of the peripheral thermoreceptors, so the hypothalamus is more responsive to central thermoreceptors than peripheral thermoreceptors.

The importance of P50

The P50 represents the partial pressure at which hemoglobin is 50 percent saturated with oxygen. Normal P50 is 27 mm HgP50 provides a means of quantifying the hemoglobin's affinity (willingness to bond) with oxygen. Reflects what are called shifts of the dissociation curve. Right shift - hemoglobin has decreased affinity, increased P50 - takes more oxygen to reach 50% (higher partial pressure to get 50% saturated) Left shift - increased affinity, decreased P50 - less oxygen to reach 50% (less partial pressure to get 50% saturated

Frank-Starling effect

The ability of the heart to change its force of contraction and therefore stroke volume in response to changes in venous return In the late 19th century, Otto Frank found using isolating frog hearts, that the strength of ventricular contraction was increased when the ventricle was stretched prior to contraction. This cardiac response to changes in venous return and ventricular volume is intrinsic to the heart and does not depend on extrinsic neurohumoral mechanisms. This observation was extended by the studies of Ernest Starling in early 20th century who found that increasing venous return to the heart, which increased the filling volume (this is the left ventricular-end diastolic volume) of the ventricle led to increased stroke volume (SV). Conversely, decreasing venous return, decreased stroke volume.

vertebrate blood composition

The centrifugal force is used to separate the components of blood, these are: The red blood cells (erythrocytes), platelets (immune cells), and plasma The red blood cells precipitate to the bottom of the centrifuge tube with the platelets above them, then, the white blood cells and the plasma at the very top. The plasma or fluid portion makes up approximately 55% of the whole blood volume in humans, the blood cells or erythrocytes (also called the hematocrit) accounts for the other 45%. There is a variation of the hematocrit among species and can be changed depending on different conditions such as acclimation to high altitude. The other blood cells, mostly immune cells are a small faction.

More animals use one of the three major respiratory strategies; cutaneous respiration, gills, or lungs.

The complexity of the respiratory system is correlated with the size of the organism. As animal's size increases, diffusion distances increase, and the ratio of surface area to volume drops. In unicellular organisms, diffusion across the cell membrane is sufficient for supplying oxygen to the cell. Unicellular and small multicellular organisms from aquatic environments can utilize the diffusion gradient to drive gas exchange with the environment. animals need to dissolve oxygen first before it reaches the cell membrane. In simple organisms such as cnidarians and flatworms, every cell in the body is close to the external environment. Their cells are kept moist and gases diffuse quickly via direct diffusion. Large animals can't rely on diffusion alone to obtain oxygen because it is a slow process, so they need both bulk flow and diffusion for gas exchange. Sponges and cnidarians here, for instance, move the external medium, which is seawater by workflow, through an internal body cavity. For a diffusion mechanism, oxygen goes inside the cells and CO2 goes out, out of the cell into the seawater. In the case of insects, they use a similar system. All insects are aerobic organisms and they must obtain oxygen from the environment in order to survive. They use the same metabolic reaction as other animals, to convert the nutrients, for instance, sugar, into chemical bond energy of ATP. The respiratory system is responsible for delivering sufficient oxygen to all cells of the body and for removing carbon dioxide that is produced as a waste product of cellular respiration. Respiratory system of insects and many other arthropods is separated from the circulatory system. It is a complex network of tubes called the trachea system that delivers oxygen- containing air to every cell of the body. In other animals like leech or earthworm, oxygen simply diffuses through the skin and is carried through the circulatory system. Earthworms and amphibians use their skin as a respiratory organ, a dense network of capillaries lies just below the skin and facilities gas exchange between the external environment and the circulatory system. The respiratory surface must be kept moist in order for the gases to disolve and diffuse across cell membrane. Other organisms have specialized respiratory organs like gills or lungs for gas exchange, and they use the ventilation to move the external medium by bulk flow across the respiratory surface.

Structure of vertebrate hearts: fish and amphibians

The heart is composed of three layers: the epicardium, myocardium, and endocardium. The inner wall of the heart has a lining called endocardium. The myocardium consists of the heart muscle cells that make up the middle layer and the bulk of the heart wall The outer layer of cells is called epicardium, of which the second layer is membranous layer structure called the pericardium, that surrounds and protects the heart and it allows for enough room for vigorous pumping, but also keeps the heart in place to reduce friction between the heart and other structures. Hearts in fish and amphibians: In fish or amphibians, the myocardium is composed largely of spongy myocardium, which is poorly vascularized. The myocardium is surrounded by a thin layer of compact myocardium that is supplied by the coronary arteries. The cardiac anatomy of fish and frogs: both fish and amphibians heart have only one ventricle. the bony fish the heart of the bony fish has just one atrium, and the amphibian has two atriums. The heart of the fish is arranged in series: the blood enters the sinus venous and from there the blood is pumped to the atrium and the ventricle. The amphibian heart: the oxygenated blood from the lungs goes to the left atrium by the pulmonary vein, the partially oxygenated blood, (deoxygenated) from the skin and tissues enters in the right atrium via sinus venous. The atria pump blood through into the ventricle but for some mechanism that is not entirely known. both bloods are kept separated. Oxygenated blood goes through systemic arteries to the rest of the body and deoxygenated blood goes to the lungs through the pulmocutaneous artery.

dissociation curves for the fetal and adult hemoglobin (Hb)

The large affinity for oxygen of fetal hemoglobin in comparison with adult hemoglobin facilitates oxygen transfer from the mother to fetus. The reason for this elevated affinity is the weaker binding of HbF (fetal) to the 2,3 DPG. 2,3-diphosphoglycerate lowers the affinity of hemoglobin A for oxygen by binding to and stabilizing deoxyhemoglobin. The cavity in the center of the four globin chains is capable of binding one molecule of 2,3-DPG between the two b-chains of the hemoglobin A whereas this is not possible for the g-chains of the hemoglobin F. P50 of the HbF is reduced in comparison to adult Hb. the important part is to understand why fetal hemoglobin has higher affinity for oxygen than the mother's one, and just the contribution of 2,3 DPG. (**P50 = PO2 in which the hemoglobin is 50% saturated with oxygen)

The law of LaPlace

The larger arteries of the body are subject to higher wall tensions than the smaller arteries and capillaries. This wall tension follows the dictates of LaPlace's Law, a geometrical relationship which shows that the wall tension is proportional to the radius for a given blood pressure. To take into account the thickness of the wall of the vessel, we add the wall stress and the wall thickness S= Pr/w In a thin vessel the wall tension is proportional to the transmural pressure times the radius of the vessel. In a thick wall vessel, the wall stress is proportional to the transmural pressure and the vessel radius but inversely proportional to the wall thickness.

amphibian lungs

The lungs of amphibians are simple sack-like structures that internally lack the complex spongy appearance of the lung of birds and mammals. The lungs of most amphibians receive a large proportion of the total blood flow from the heart. Even though the amphibian ventricle is undivided, there is surprisingly little mixture of blood from the left and right atrial chambers within the single ventricle. As a consequence, the lungs are perfused primarily with deoxygenated blood from the systemic tissues. The mechanism of lung inflation in the amphibians is the buccal cavity (mouth, throat) this is a pumping mechanism that also functions in air-breathing fishes. To produce inspiration, the floor of the mouth is depressed, causing air to be drawn out into the buccal cavity through the nostrils. The nostrils are then closed, and this creates a positive pressure in the mouth cavity and drives air into the cavity, into the lungs. Expiration is produced by contraction of the muscles of the body wall.

Mammalian cardiac cycle and BP

The main purpose of the heart is to pump blood through the body. It does so in a repeating sequence called the cardiac cycle, which is the coordination of the filling and emptying of the heart of blood, by electrical signals that cause the heart muscles to contract and relax. The human heart beats over 100 thousand times per day. In each cardiac cycle, the heart contracts, and this is called systole, pushing out the blood and pumping the blood through the body. This is followed by the relaxation phase that is called diastole, where the heart fills with blood. The atria contract at the same time, forcing blood through the the atrioventricular valves into the ventricles. The closing of the atrioventricular valves produces a monosyllabic "lup" sound. Following a brief delay, the ventricles contract at the same time, forcing block through the semilunar valves into the aorta and the artery transporting blood to the lungs via the pulmonary artery. Closing of the semilunar valves produces monosyllabic "dup" sound. When systemic arterial blood pressure is measured, it is recorded as a ratio of two numbers. Example, 120 over 80 is a normal adult blood pressure expressed as systolic pressure over diastolic pressure. The systolic pressure is the higher value, typically around 100 millimeters of mercury and reflects the arterial pressure resulting from the ejection of blood during ventricular contraction or systole. The diastolic pressure is the lower value, usually around 80 millimeters of mercury and represents the arterial pressure of blood during ventricular relaxation or diastole. During the cardiac cycle, the two ventricles of the mammalian heart contract simultaneously, but the left ventricle contracts much more forcefully than the right ventricle and develops much higher pressure. Blood from the left ventricle travels via the aorta to the organs of the body and the blood from the right ventricle travels to the lungs via pulmonary artery. The pulmonary circuit has relatively low total resistance because of the very large number of capillaries arranged in parallel and the relatively short distance traveled. This is why the resistance is low, because the right side of the heart does not need to pump so hard to drive blood through the lungs, which protects the small blood vessels of the lungs

Mean Arterial Pressure (MAP), Hypoxia, and Baroreceptors

The mean arterial pressure represents the average pressure of blood in the arteries, this is the average force driving blood into the vessels that serves the tissues. mean arterial pressure can be approximated by adding the diastolic pressure to 1/3 of the pulse pressure (or systolic pressure) minus the diastolic pressure. The difference between the systolic pressure and the diastolic pressure, is the pulse pressure. Ex) an individual with a systolic pressure of 120 millimeters of mercury and diastolic pressure of 80 millimeters of mercury would have a pulse pressure of 40 millimeters of mercury. Normally, they mean arterial pressure falls within the range 70-110 millimeters of mercury. If the value falls below 60 millimeters of mercury for an extended time, blood pressure will not be high enough to ensure circulation to and through the tissues, which results in is ischemia, or insufficient blood flow A condition called hypoxia (inadequate oxygenation of the tissues) commonly accompanies ischemia. The term hypoxemia refers to low levels of oxygen in systemic arterial blood. Neurons are especially sensitive to hypoxia, and may die or be damaged if blood flow and oxygen supplies are not quickly restored. The baroreceptor reflex is the primary means to regulate the mean arterial pressure. Baroreceptors are stretch-sensitive mechanoreceptors located in the carotid sinus and in the aortic arch, and in the the wall of the major blood vessels. The most important are in the carotid artery and in the aorta. Their function is to sense pressure changes by responding to change in the tension of the arterial wall. The baroreflex mechanism is a fast response to changes in blood pressure. The cardiovascular control center in the medulla oblongata of the central nervous system integrates the inputs coming from action potentials, sending signals via primary afferent neurons. follows negative feedback

mitochondrial respiration

The mitochondria respiration or respiration is the most important generator of cellular energy under most circumstances, it is a process of energy conversion of substrate into ATP using chemical energy found in glucose and other nutrients. This process consumes oxygen and produces carbon dioxide. Oxygen molecules move down its gradient into the mitochondria and CO2 moves in opposite direction.

effects of norepinephrine on heart rate

The nervous and endocrine system modulate the heart rate by altering the rate of pacemakers potential in the cells of the sinoatrial node, or sinus venous. The sympathetic neurons and adrenal medulla release norepinephrine, and epinephrine respectively. Epinephrine, also called adrenaline, is a hormone that is secreted mainly by the medulla of the adrenal gland, and that functions primarily to increase cardiac output and raise glucose levels in the blood. Epinephrine typically is released during acute stress while epineprhine has slightly more of an effect on your heart, norepinephrine has more of an effect on the blood vessels. Epinephrine: -In this case, the stimulatory effects of epinephrine are mediated through the activation of second messenger known as cyclic adenosin monophosphate, cAMP -The activation of this molecule results in the stimulation of cell signaling pathway that act to increase heart rate. -Epinephrine activates the adenylate cyclase signal transduction pathway that opens cation and T-type calcium channels, which increases the rate of depolarization of the pacemaker potential. Norepinephrine -the effects of the norepinephrine in the heart rate is mediated by binding to the adrenergic receptor, activating adenylate cyclase (AC) pathway -leads to opening the funny channels and and the T- type calcium channels, so this is going to elicit a depolarization.

inotropy

The nervous system, and endocrine system can modulate the rate and the strength of the contraction, and this it termed "inotropy". Inotropic agents or ionotrops, are medicines that change the force of your heart's contraction. Both norepinephrine and epinephrine can increase contractility.

membranes can also be modified by endocytosis and exocytosis

The old membrane is removed by endocytosis and phospholipids are synthesized de novo within the endoplasmic reticulum, packed into vesicles that fuse with cellular membranes. The process of endocytosis and exocytosis remove undesirable phospholipids replacing them for the ones more optimal depending on the temperature.

Oxygen equilibrium curves

The oxygen equilibrium curve of a respiratory pigment, which shows the relation between the O2 binding by the pigment and the O2 partial pressure, is a key tool for interpreting respiratory-pigment function. In a), we can see the oxygen equilibrium curve showing the relationship between the partial pressure of oxygen in the plasma and the percentage of oxygenated respiratory pigment in a volume of blood. As the partial pressure increases the solution, more pigment molecules will bind oxygen until the available molecules are fully bound to oxygen, which is the saturation point. In b), we can see the oxygen content of blood that contains differing amounts of hemoglobin. P50 is the oxygen partial pressure that measures how readily a pigment binds oxygen. It is then, the oxygen partial pressure at which the pigment is 50% saturated.

hematocrit

The percent of the volume of whole blood that is composed of red blood cells as determined by separation of red blood cells from the plasma usually by centrifugation.

cooperativity

The shape of the oxygen equilibrium curve depends on the degree of cooperativity among O2-binding sites on respiratory-pigment molecules. When there is no cooperativity—as is the case when each molecule has only a single O2-binding site—the oxygen equilibrium curve is hyperbolic. The curve is sigmoid when molecules have multiple O2-binding sites that exhibit positive cooperativity. Hyperbolic curves are the norm for myoglobins; sigmoid curves are the norm for blood pigments. Myoglobin is a monomeric respiratory pigment that contains one single heme molecule and in contrast, hemoglobin is tetrameric. When a hemoglobin molecule is fully deoxygenated it is rigid and is called tense as is shown in b), and when is fully oxygenated is called relaxed because adopts a loose conformation. Oxygen affinity increases progressively as each oxygen binds and the molecule adopts an increasingly relaxed conformation.

metalloproteins

The solubility of oxygen in plasma is low, so to combat the oxygen solubility limitation, there are some proteins in the blood of many animals called metalloproteins. They bind reversibly with O2 at specific O2-binding sites associated with the metal atoms in their molecular structures. In hemoglobins, the unit molecule consists of heme bonded with protein (globin). The heme structure—an iron (ferrous) porphyrin—is identical in all hemoglobins. The globin, however, varies widely among species and among different molecular forms of hemoglobin within any single species. Hemocyanins are the second most common of the respiratory pigments in animals. They contain copper and turn bright blue when oxygenated. There are two types of hemocyanins, which are of separate evolutionary origin: arthropod hemocyanins, and mollusc hemocyanins. Hemocyanins are always dissolved in the blood plasma. Hemerythrins don't contain heme, they are only iron-containing respiratory pigments that have a limited and scattered distribution, occurring in three or four different invertebrate phyla.

resting homeotherm

The thermoneutral zone is defined as the range of ambient temperatures where the body can maintain its core temperature, and the animal uses no additional energy to maintain it. Here we can see the purple line as the range of ambient temperatures and the homeothermic endotherm maintains constant body temperature within this range. If the temperature decreases below certain value called lower critical temperature (LCT) the animal has to increase its metabolic rate (MR) to generate the heat to help maintain a constant body temperature. If the animal can't maintain the constant core temperature below certain point, hypothermia results. On the other hand, if ambient temperature increases above the upper critical temperature or UPC, the animal increases metabolic rate to shed heat, if the temperature is too high and the animal can't control its body temperature, hyperthermia results.

Phospholipid remodeling

There are two ways that cells use to modify the membrane composition depending on the temperature: -in situ modification and -the novo synthesis The nature of the diet affects the type of fatty acids within the membrane because the modifications of the fatty acids begin from fatty acids coming directly from the diet. Here we can se the enzymes that alters the structure of the individual phospholipids.

phospholipids and membrane fluidity

There is an effect of temperature on macromolecular function and metabolism, so ectotherms and poikilotherms have to tolerate or compensate for the effects of the adverse temperature. Proteins and lipids are the substances more affected by the effect of temperature, due to the weak bonds of these molecules that are disrupted at high temperatures. So the effects of temperature, depend on the relative importance of each type of bond interaction. The phospholipids interactions and strong but at the same time, they should be fluid enough to allow proteins to move within the membrane. The low temperature makes lipids to solidify, and this affects protein movement, and the high temperatures liquefy the membrane compromising its integrity, reducing in both cases its effectiveness. Ectothermic animals reduce the deleterious effects of temperature by a process called homeoviscous adaptation. There are three mechanisms directed to phospholipids and one mechanism directed to cholesterol. We can see in the figure the membrane composition changes to alter the membrane fluidity. The cells can do that by changing the fatty acid length, by saturating the lipid membrane, or based on the phospholipid type, and cholesterol content. -The fatty acid chain length: Phospholipids of shorter chain length can form less interactions with adjacent fatty acids so they become highly mobile. -Saturation: Fewer bonds in the fatty acid chains makes the membrane more fluid. Not only the amount of bonds is critical, also the position of the bond. -Phospholipid classes: The type of the polar head group determines the ability of the phospholipid to interact, so phosphatidylcholine (PC) is more common in membranes of warmer climates, and phosphatidylethanolamine (PE) is more common in cold climates. -The cholesterol content, gives stability and prevents the membrane from solidifying.

Thermal energy: sources and sinks

Thermal energy can move from the animal to the environment, or from the environment to the animal, depending on the temperature gradients. Metabolism (the biochemical reactions occurring within the body) is the main source of thermal energy in most animals. However, other important sources and sink for thermal energy also affect an animal's thermal status. In this figure we can see that the body temperature of an animal is influenced by heat exchange with the environment. The snake gets radiant energy from the sun, and the thermal energy radiated by its surroundings, and at the same time, there is a conduction because the snake exchanges thermal energy with the surface in contact with its body, and the movement of the air enhances the efficiency of thermal exchange by convection. In general, we have to consider two temperatures: TA (ambient temperature) and TB (body temperature)

Why do reptiles sunbathe? Why do dogs pant when they're hot? Animals have quite a few different ways to regulate body temperature!

These thermoregulatory strategies let them live in different environments, including some that are pretty extreme. Based on the stability of body temperature, we can distinguish between poikilotherms and homeotherms. Homeotherms are animals that have a constant body temperature. Poikilotherms are animals whose body temperature adjusts depending on the environment. The animals can be divided into endotherms and ectotherms based on their temperature regulation. Endotherms, such as birds and mammals, use metabolic heat to maintain a stable internal temperature, often one different from the environment. Ectotherms, like lizards and snakes, do not use metabolic heat to maintain their body temperature but take on the temperature of the environment. Both endotherms and ectotherms have adaptations by natural selection—that help them maintain a healthy body temperature.

elastic recoil

This pressure difference between pulmonary alveoli and the pleural cavity is called the transpulmonary pressure and this pressure causes elastic recoil of lung. Elastic recoil refers to the lungs tendency to deflate following inflation.

RESPIRATORY SYSTEM in CRUSTACEANS

To meet the metabolic requirements for gas exchange, crustacean respiratory system requires two components: gill ventilation and perfusion. All crustaceans possess some means of moving the external medium past their gas exchange surfaces. In some smaller crustaceans, an internal circulatory system to transport oxygen may not be necessary because sufficient gas exchange can occur by diffusion. Decapods, and other large crustaceans, on other hand, depend on a dual hydraulic pump in the system to effect gas exchange between the external medium and the blood.

PRESSURE23THE EFFECT of GRAVITY on BLOOD PRESSURE

When a human is lying down, venous blood volumes and pressures are distributed evenly throughout the body. Although the arterial blood pressure is slightly higher in the heart. When the person suddenly stands upright, gravity acts on the vascular volume causing blood to accumulate in the lower extremities

Albumin is created is an important protein found in the blood. If a vial of blood is centrifuged, in which of the following layers would albumin be found? a. The plasma layer The leukocyte layer The red blood cell layer The hematocrit The darker-colored layer

a

Cardiomyocytes are similar to skeletal muscle because: a. they are striated b. they pulse rhythmically c. they are used for weight lifting d. they beat involuntarily

a

Hemoglobin is the most important component of red blood cells. How are red blood cells different from other cells of the body? a. They lack a nucleus b. They lack a cell membrane c. They contain protein support for their membranes d. They are produced in the liver e. They are larger than all other cells and red

a

In the myogenic response, ________. a. vascular smooth muscle responds to stretch b. endothelins dilate muscular arteries c. ventricular contraction strength is decreased d. muscle contraction promotes venous return to the heart e. None of the answers are correct

a

In the renin-angiotensin-aldosterone mechanism, ________. a. aldosterone prompts the kidneys to reabsorb sodium b. decreased blood pressure prompts the release of renin from the liver c. aldosterone prompts increased urine output d. all the answers are correct

a

Muscular arteries have a prominent internal elastic lamina inside and also have smooth muscle. These include medium and small arteries, which have progressively less elastic fibers and smooth muscle as the artery becomes smaller with branching. Correct Answer True You Answered False

a

Of the following, which does not explain why the partial pressure of oxygen is lower in the lung than in the external air? Correct Answer Lungs exert a pressure on the air to reduce the oxygen pressure. Oxygen is moved into the blood and is headed to the tissues. You Answered Carbon dioxide mixes with oxygen. Air in the lung is humidified; therefore, water vapor pressure alters the pressure. None of the answers are correct

a

Purkinje fibers______ Correct Answer are specialized fibers that take the electrical impulses from the atria to the apex of the heart are special fibers located in the apex of the heart You Answered are special fibers that signal the apex of the right ventricle are fibers that conduct impulses from the atria to the ventricles All the answers are correct

a

Slight vasodilation in an arteriole prompts a ________. a. huge decrease in resistance b. slight increase in resistance c. huge increase in resistance d. slight decrease in resistance e. the resistance is maintained

a

The inspiratory reserve volume measures the ________. a. amount of air that can be further inhaled after a normal breath b. amount of air remaining in the lung after a maximal exhalation c. amount of air the can be further exhaled after a normal breath d. amount of air that the lung holds

a

The maximum amount of air that can be moved in and out of the lungs during a single breath is called: a. vital capacity b. residual volume c. inspiratory capacity d. respiratory capacity e. functional residual capacity

a

The partial pressure of oxygen at the top of Mount Teide in Spain (12,198 ft), is mmHg. Which of the following would bind the most oxygen in equilibrium with the air on Mount Mount Teide? a. Myoglobin b. They would all bind the same c. HbA d. HbF e. 2,3-bisphosphoglycerate

a

The sum of the four primary lung volumes (tidal volume, inspiratory reserve volume, expiratory reserve volume, and residual volume) equals; a. the total lung capacity (TLC) b. the maximum ventilatory volume c. the vital capacity d. the functional residual capacity

a

What is the function of heart valves? Correct! Keep blood moving unidirectionally Mix blood thoroughly Propel blood Slow down blood flow Control the amount of pumped blood

a

What might be an unintended consequence of excess stimulation of hematopoietic (formation of blood components) stem cells? Correct Answer Blood clot Decrease white blood cell count Decrease hematocrit You Answered None of these Decrease red blood cell count

a

Where and by what cells is hemoglobin made? a. in bone marrow, by RBC precursors b. in the spleen, by monocytes c. in the bone marrow, by platelets d. in the liver, by agranulocytes e. in the spleen, by granulocytes

a

Where does blood entering the right atrium come from? a. Systemic circulation b. Pulmonary circulation c. aorta d. right ventricle e. left ventricle

a

Which of the following are most important in explaining how the body changes the resistance of arterioles to blood flow? a. Smooth muscle cells b. Skeletal muscle cells c. Arterial valves d. Endothelial cells e. Fibroblasts

a

Which of the following best describes veins? a. thin walled, large lumens, low pressure, have valves b. thick walled, small lumens, low pressure, lack valves c. thin walled, small lumens, high pressure, have valves d. thick walled, large lumens, high pressure, lack valves e. thick walled, small lumens, high pressure, lack valves

a

Which of the following helps cool the body temperature? Correct Answer Peripheral vasodilation You Answered Peripheral vasoconstriction Shivering None of these Hyperventilation

a

Which of the following is a mechanism by which blood flow to the kidneys might decrease during exercise? a. Blood vessels in the kidneys constrict and blood vessels in skeletal muscles dilate. b. Skeletal muscle fibers absorb fluid and swell, decreasing intravascular volume c. Contraction of skeletal muscles increases pressure in kidneys d. Buildup of lactic acid in cardiac muscle fibers decreases contraction ability

a

Which of the following is most likely to decrease oxygen's affinity to hemoglobin in the bloodstream? a. Low pH b. Low CO2 c. low temperature d. high pH

a

Which of the following vessels transports blood from the lungs to the heart? Correct! Pulmonary veins Inferior vena cava Superior vena cava Pulmonary arteries Aorta

a

Which of the following will decrease hemoglobin's affinity for oxygen? Correct Answer Decrease the partial pressure of oxygen You Answered Decrease the acidity of the blood Decrease the temperature increase the partial pressure of oxygen None of these

a

Which of the following would you NOT expect to increase systolic blood pressure: a. Changing for laying down to standing up b. Experiencing a nightmare c. Taking a medication that increases fluid retention in the kidneys d. Changing for standing up to laying down e. Taking a medication that causes vasoconstriction

a

Why would it be unlikely for a clot formed in the venous system to cause a heart attack or stroke? Correct Answer a clot formed in the venous system would get trapped in the lungs before getting into systemic circulation. clots fall apart as they travel through the blood venous clots are rare because pressure in the venous system is so low You Answered venous blood is less likely to clot due to its lower oxygen concentration venous blood is less likely to clot due to its lower heparin concentration

a

will increase the resistance to the flow of the pulmonary vascular system? a. secrete pulmonary surfactant b. form the walls of the alveoli c. secrete elastic fibers into the interstitial space surrounding the alveoli d. absorb particulate matter by phagocytosis e. All the answers are correct

a

Spirometer

a device to measure the volumes of air inhaled and exhaled under different conditions it measures the lung capacity and lung volume. tidal volume- the total volume of air moved in one ventilatory cycle. dead space- some air that enters in each ventilatory cycle and does not participate in gas exchange, contributing to what is termed dead space of the system, which consist in two a spaces: the anatomical and the alveolar dead spaces. The total amount of fresh air that is involved in gas exchange during a respiratory cycle, is equal to the tidal volume minus the dead space, and in mammals is symbolized as Va. lung capacity and the lung volume with the inspiration, the line goes up, and with expiration the line goes down in the curve. At rest, most animals do not use the full capacity of the lungs, So the tidal volume is lower than the maximum possible amount of air that can be inhaled or exhaled. These four main lung volumes that are necessary to characterize lung function, and these parameters are measured directly. The first three lung volumes are measured by standard spirometers: the tidal volume, then we have the inspiratory reserve volume, which is the maximal amount of air that can be inhaled over and above the resting tidal volume, then we have the expiratory reserve volume, which is the maximal amount of air that can be forcibly exhaled over and above the resting tidal volume, and then we have the residual volume, which is the volume of air remaining in the lungs after a maximum exhalation. So the total lung the capacity is the sum of these terms. There are other parameters called the four main lung capacities that are calculated from the lung volumes and are used by clinicians to assess certain types of disease.

Diphenyl hexatriene

a fluorescent probe that is incorporated to biological membranes to study the structural and dynamics of hydrophobic regions in the membranes. In the figure we can see that membranes treated with this dye, the optical properties change in relation to the membrane fluidity. Anisotropy is the property of the probe to alter the behavior of the light, so is inversely related to fluidity, this means that at higher temperatures, a decrease in anisotropy property reflects and increase in fluidity. So this is a way to measure the fluidity of the membrane.

mammalian conduction pathway

a series of cells that not contract but conduce the impulse, and can undergo rhythmic depolarization similar to pacemaker cells. These are fast electrical conducting pathways. In this figure, we can see how the electrical signals move through the mammalian heart. In a mammal heart, the pacemaker is in the sinus node. Electrical activity initiated in the peacemaker spreads over the muscle of two atria, and then, after a slight delay to the muscles of the ventricles. At this point, electrical activity is conducted rapidly through the atrioventricular bundle, to the apex of the ventricle and then continues through specialized cells that they are the Purkinje fibers up the walls of the ventricles. This arrangement allows the contraction to begin at the apex of the heart, and spreads upward to squeeze out the blood in the most efficient way. It also ensures that both ventricles contract at the same time. Structural specialization in Purkinje fibers, such as numerous gap junctions, facilitate rapid conduction through these fibers.

effects of acetylcholine on heart rate

acetylcholine is released by parasympathetic nerves and regulates the change in the heart rate and contractility required for proper cardiovascular function, via muscarinic receptors, opposing the activity of the sympathetic nervous system (epinephrine pathway) Acetylcholine binds to muscarinic receptors and activates a signal transduction pathway that closes calcium channels and open potassium channels. Prevents calcium from entering the cell and allows potassium to exit, leading to net hyperpolarization, so the total time needed for the pacemaker potential to depolarize the cell increases. Therefore, signaling leads to a reduction in heart rate, the contractile forces of the atria and the conduction velocity of both the sinoatrial and atrioventricular nodes. The effects of the acetylcholine on the heart rate is mediated by muscarinic receptors in the heart.

The aorta and the role of skeletal muscle and respiratory pumps

acts as a pressure reservoir and avoids the fluctuation in blood pressure mostly because of its elastic nature. The blood pressure returns to the veins with relatively low pressure. There are two major pumps that move the blood back to the heart: the skeletal muscle, and respiratory pumps. The muscle contraction squeezes the veins and the pressure increases in their blood vessels, the valves closest to the heart open and the venous return to the heart increases. The respiratory pump also draws blood to the heart. The contraction of skeletal muscle surrounding a vein, compresses the blood and increases the pressure in that area. This action forces blood closer to the heart where the venous pressure is lower. Note the importance of the one way valves to assure that blood flows only in the proper direction. The ability of a blood vessel wall to expand and contract passively with changes in pressure, is an important function of large arteries and veins.

vertebrate circulatory system

all vertebrates share a common circulatory structure in which the heart pumps blood to a large artery (aorta) The aorta branches into smaller arteries, ending in small arteries that go into the tissues. Within the tissues, the arteries branch into arterioles that direct flow into the capillary beds, which are made of dense networks of thin vessels called capillaries, where the substances diffuse to the tissues across the walls of the capillaries. At the end of the capillary beds, capillaries come together into small vessels, called venules, which in turn come together into larger vessels called veins that return blood to the heart. Some arteries can form anastomosis which are connections between two blood vessels, and allows blood to flow in one route, if one of the route is locked. Ex) the arteries in the joints contain many anastomoses, allowing the blood to flow even if a joint is bending and closing off one of the arteries. They are more frequent in the areas farther from the heart.

A form of circulatory shock common in young children with severe diarrhea or vomiting is ________. a. obstructive shock b. hypovolemic shock c. anaphylactic shock d. hemorrhagic shock

b

All the lung volumes can be measured by spirometry except; a. inspiratory reserve volume b. residual volume c. tidal volumes d. expiratory reserve volume

b

Closer to the heart, arteries would be expected to have a higher percentage of ________. a. endothelium b. elastic fibers c. collagenous fibers d. smooth muscle fibers

b

Given a person who has a tidal volume of 450 ml, an anatomic dead space of 100 ml, and a breathing rate of 12 breaths per minute, calculate the alveolar ventilation rate. *(equation to calculate the alveolar ventilation rate= Tidal Volume−Dead Space Volume)×Respiratory Rate. a. 1200ml/min b. 4200 ml/min c. 5400 ml/min d. 250ml/min e. 350 ml/min

b

Which of these statements about pulmonary surfactant is not true? Pulmonary surfactant: a. is produced by type II alveolar cells b. increases the surface tension of fluid lining the alveolar surface c. is deficient in some premature babies d. consists mainly of phospholipid

b

Clusters of neurons in the medulla oblongata that regulate blood pressure are known collectively as ________. a. the cardiomotor mechanism b. angioreceptors c. the cardiovascular center d. baroreceptors

c

Venoconstriction increases which of the following? a. Blood pressure within the vein b. Blood flow within the vein c. All the rest of the answers are correct d. Return of blood to the heart

c

White blood cells ________ a. can be classified as granulocytes or agranulocytes b. defend the body against bacteria and viruses c. all of the rest of the answers are correct d. are also called leucocytes

c

The Root effect

ccurs only rarely, is a substantial reduction of the oxygen-carrying capacity of a respiratory pigment caused by a decrease in pH and/or an increase in CO2 partial pressure. The decrease in pH cause an exaggerated right shift of the oxygen equilibrium curve. In teleost fish for example.

factors that influence hemoglobin's affinity for oxygen

changes in: pH• Temperature• Carbon Dioxide• 2,3-DPG and the presence of: hemoglobin variants• Fetal Hemoglobin• Carbon Monoxide Hemoglobin• Hemoglobin S (sickle cell)• Methemoglobin

In a blood pressure measurement of 110/70, the number 70 is the ________. a. pulse pressure b. systolic pressure c. mean arterial pressure d. diastolic pressure

d

Platelet plug formation occurs at which point? a. when large megakaryocytes break up into thousands of smaller fragments b. when platelets are dispersed through the blood stream c. when large megakaryocytes break up and attracted to cytokines low concentrations d. when platelets are attracted to a site of blood vessel damage e. All the answers are correct

d

The dead space of the airways is: a. any region of the lung where the air supply has been interrupted b. the pleural space c. the volume of air remaining in the lungs after a maximal expiration d. the space where exchange of O2 and CO2 with blood does not occur

d

The red blood cells of birds differ from mammalian red blood cells because: a. they are not different from mammalian's erythrocytes b. they are white and have nuclei c. they fight disease d. they have nuclei e. they lack of hemoglobin

d

Which of the following statements is true? a. All of the above are true. b. The longer the vessel, the lower the resistance and the greater the flow c. Increased viscosity increases blood flow d. As blood volume decreases, blood pressure and blood flow also decrease

d

hypertension (HTN)

defined as chronic and persistent blood pressure measurement of one hundred forty over and ninety millimeters or Hg or above. About 16 million Americans currently suffer from hypertension. Secondary hypertension accounts for approximately five to 10% of all cases of hypertension with their remaining being primary hypertension. Secondary hypertension has an identifiable cause whereas primary hypertension has no known cause. hypertension is typically a silent disorder, therefore, hypertensive patient may fail to recognize the seriousness of their condition, and fail to follow the treatment plan. The result, it's often a heart attack or stroke. Hypertension may also lead to an aneurysm, the ballooning of a blood vessel caused by a weakening of the wall, or peripheral arterial disease, which is the obstruction of vessels in peripheral regions of the body, chronic kidney disease, or heart failure. The baroreceptors don't detect the increase of blood pressure because with chronic hypertension, the baroreceptors adapt to the elevated blood pressure, so the central nervous system detects as normal the high blood pressure and don't initiate the baroreceptor reflex. There is much uncertainty about the pathophysiology of hypertension. A small number of patients (like 5%) have an underlying renal or adrenal disease as the cause for their raised blood pressure. In the remainder, however, that however, no clear single identifiable cause is found and the condition is labeled as essential hypertension. Treatment: Blockers of the renin-angiotensin-aldosterone system, (RAAS) (renin inhibitors) angiotensin-converting enzyme (ACE) inhibitors, or Angiotensin II type receptor antagonist, also mineralocorticoid receptor antagonists, are a cornerstone in the treatment of hypertension. Other pathophysiologies of the cardiovascular system: arteriosclerosis- the thickening and loss of elasticity in arteries. When arteriosclerosis is caused by fatty deposits of cholesterol in artery walls, the condition is atherosclerosis. Such irregularities in the walls of blood vessels often cause blood to clot around them, forming a thrombus. When a bit of the thrombus breaks off, and is carried by the blood to lodge elsewhere it is an embolus. If the embolus blocks one of the coronary arteries, the person has a heart attack. The portion of the heart served by the branch of the coronary artery that is blocked is starved for oxygen. It might be replaced by scar tissue if the person survives.

Electrocardiogram (ECG)

detects the electrical signal from the depolarization of cardiac muscle. It records all action potentials from various parts of the heart, including pacemakers, the conducting pathways, and the contractile cells. The waves recorded are not action potentials, and do not represent specific depolarizations, but reflect the electrical activity of the heart as a whole. The signal is initiated as in "a" at the sinoatrial valve. The signal then spreads to the atria causing them to contract. The signal is delayed at the atrioventricular node (b) before it passes on to the heart apex (c). The delay allows the atria to relax before (d) the ventricles contract. The final part of the electric electrocardiogram, prepares the heart for the next beat.

three major types of capillaries: continuous, fenestrated, and sinusoid capillaries.

differ according to their degree of "leakiness" the continuous capillary, which is found in almost all vascularized tissues. -The most common type of capillary - are characterized by a complete endothelial lining with tight junctions between endothelial cells. -Although a tight junction is usually impermeable and only allows for the passage of water and ions, they are often incomplete in capillaries, leaving intercellular clefts that allow for exchange of water and other very small molecules between the blood plasma and the interstitial fluid. -Those capillaries in the brain are part of the blood brain barrier. In the brain, there are tight junctions and no intercellular clefts, plus a thick basement membrane combine to prevent the movement of nearly all substances. A fenestrated capillary is one that has pores (or fenestrations) in addition to tight junctions in the endothelial lining. -These make the capillary permeable to large molecules, and the number of fenestrations and their degree of of permeability vary, however, according to their location, fenestrated capillaries are common in the small intestine, which is the primary site of nutrient absorption, as well as in the kidneys, which filter the blood. -They are also found in the choroid plexus of the brain and many endocrine structures, including the hypothalamus, pituitary, pineal, and thyroid gland. A sinusoid capillary (or sinusoid) is the least common type of capillary. -Sinusoid capillaries are flattened, and they have extensive intercellular gaps and incomplete basement membranes, in addition to intercellular clefts and fenestrations. -These very large openings allow for the passage of the largest molecules, including plasma proteins and even cells. -Blood flow through sinusoids is very slow and are found in the liver, bone marrow, and many endocrine glands including the pituitary and the adrenal glands. -For example, when bone marrow forms new blood cells, these cells must enter the blood supply and can only do so through the large openings of a sinusoid capillary. They cannot pass through the small openings of continuous or fenestrated capillaries.

circulatory system in air breathing animals v fish

different vertebrate circulatory systems vary depending on the respiratory strategy of the animal. In fish, blood goes from the heart through the aorta to the gills, and then to the rest of the body, then returns to the heart. -Single-circuit circulatory system Air-breathing animals have a double-circuit circulatory system with two bumps located in series. -The pulmonary circuit moves the blood from the right side of the heart to the lungs, and back to the heart. -The systemic circuit moves blood from the left side of the heart to the head, and to the body, and then returns the blood to the right side of the heart to repeat the cycle. -In the case of amphibians and reptiles, they follow a different pattern because they have an incompletely divided heart, so the deoxygenated blood coming from the systemic circuit, and the oxygenated blood coming from the pulmonary circuit mix. -In many species, the two streams of blood returning to heart are kept partially separated but the mechanism for this separation is not fully elucidated.

Development of the human heart

during early embryonic development in fish, most of the gas exchange occurs across the skin and the gills only gradually take over as embryo develops. In air-breathing animals, the lungs assume the role in gases exchange after metamorphoses in amphibians and after birth or hatching in the reptiles, birds, and mammals. Humans: The human heart is the first functional organ to develop. It begins beating, and pumping blood around day 21 or 22. This emphasizes the critical nature of the heart in distributing blood through the vessels and the vital exchange of nutrients, oxygen, and wastes both to and from the developing baby. The critical early development of the heart is reflected by the prominent heart bulge that appears on the anterior surface of the embryo. As the primitive heart elongates, it begins to fold within the pericardium, eventually forming an S shape, which places the chambers and major vessels into an alignment similar to the adult heart. This process occurs between days 23 and 28. The remainder of the heart develops in a pattern that includes the development of the septa and valves and remodeling of the actual chambers.

An obese patient comes to the clinic complaining of swollen feet and ankles, fatigue, shortness of breath, and often feeling "light-headed." She works in a bank, a job that requires her to stand all day. Outside of work, she engages in no physical activity. Which of the following is not true related to her signs and symptoms? a. People who stand upright all day and are inactive overall have very little skeletal muscle activity in the legs b. Cardiac output is reduced c. Excess weight causing pressure on veins can result in peripheral edema (excessive fluid trapped in the tissues) d. Oxygenation of tissures throughout the body is reduced e. Venous return to the heart is increased, that is why she feels "light headed"

e

As animal size increases and diffusion distances increase, large animals ________. a. the tracheal system includes a diffusion mechanism b. they just need an open circulatory system c. None of the answers are correct d. can rely on diffusion alone for gas exchange, like cnidarians e. need other mechanisms to obtain oxygen

e

Which of the following changes will increase the resistance to the flow of the pulmonary vascular system? a. moderate exercise b. hyperventilating for 1 minute c. aerobic exercise d. anemia e. moving to high altitude

e

Which of the following respiratory systems is not closely associated with a blood supply? a. The parabronchial lung b. Fish gills c. The outer skin of earthworms d. Vertebrate lungs e. Tracheal systems in insects

e

Effect of temperature on oxygen equilibrium curves

elevated blood temperatures often decrease the O2 affinity of respiratory pigments. Temperature is related to metabolism, and increased temperature causes increased metabolism, which results in an increased cellular need for O2. The hemoglobin's affinity decreases and helps unload (removal from a vehicle) O2 Hypothermia results in a decrease metabolic rate, there is a Decrease in Oxygen need, and the affinity increases and decreases the unloading

mammalian lungs

experience bi-directional air flow over the gas exchange surface The conducting airways in the mammals are not involved in gas exchange. The end of the trachea bifurcates to the right and left lungs. In lungs, air is diverted into smaller and smaller passages or bronchi. Each bronchus divides many times, creating smaller and smaller diameter bronchioles as they spread through the lung. Like the trachea, the bronchi are made of cartilage and smooth muscle. At the bronchioles, the cartilage is replaced with elastic fibers. Bronchi are innervated by nerves of both parasympathetic and sympathetic nervous system, that control muscle contraction (this is the parasympathetic) or relaxation (the sympathetic) in the bronchi and bronchioles. The terminal bronchioles subdivided into microscopic branches called respiratory bronchioles. The respiratory bronchioles subdivide into several alveolar ducts. Numerous alveoli and alveolar sacs surround the alveolar ducts. The alveolar sacs resemble bunches of grapes. At the end of each duct, approximately 100 alveolar sacs, each containing 20 to 30 alveoli that are 200 to 300 microns in diameter. Gas exchange occurs only in alveoli. The alveolar epithelium is composed of two types of cells: Type one alveolar cells that are responsible for gas exchange, and type 2 alveolar cells that play a role in multiple functions and maintain fluid balance, and secreting pulmonary surfactant, which is a mixture of lipids and proteins. The main function of surfactant is to low with the surface tension at the air- liquid interface within the alveoli of the lung. This is needed to lower the work of breathing and to prevent alveolar collapse at end-expiration. The lungs are pyramid-shape, the left lung occupies a smaller volume than the right, the cardiac notch, is an indentation on the surface of the left lung, and it allows space for the heart. They are connected to the trachea by the right and left bronchi, on the inferior surface, the lungs are bordered by the diaphragm. The diaphragm is the flat dome-shaped muscle located at the base of the lungs and thoracic cavity. The lungs are enclosed by the pleurae, which perform two major functions: They produce pleural fluid and create a division between major organs that prevents interference due to the movement of the organs, while preventing the spread of infection. The pleural sac consists of two layers of cells with a small amount of fluid between them. In a healthy person, the pleural pressure remains negative relative to atmospheric pressure throughout the entire respiratory cycle.

Structure of vertebrate hearts: non-crocodilian reptiles

heart has three chambers. The heart muscle is asymmetrical as a result of the distance blood must travel in the pulmonary and systemic circuits.

The lymphatic system

helps maintain fluid balance in the body by collecting excess fluid and particulate matter from tissues and depositing them in the bloodstream. subsystem of the circulatory system, in vertebrates body that consists of a complex network of vessels, tissues and organs. It also helps defend the body against infection by supplying disease-fighting cells called lymphocytes. Lymph is similar in composition of blood, except that it lacks blood cells and large proteins and it is formed from blood by an ultrafiltration in the small vessels. The lymphatic system pumps this ultrafiltrate through the body and returns the ultrafiltrate to the circulatory system. Lymphatic vessels can be found in all of the vascularized organs and tissues except retina, bone, and brain

You measure a patient's blood pressure at 130/85. Calculate the patient's pulse pressure and mean arterial pressure. Determine whether each pressure is low, normal, or high.

high

Brown adipose tissue (BAT)

in contrast to white fat, can dissipate significant amounts of chemical energy through thermogenesis. Mammals possess this unique way of generating heat, and is located, in general, in the back and shoulder region. It is very important in small mammals and newborns. This process can be activated by certain stimuli, such as cold exposure, and is associated with increased energy turnover and lower body fat mass. BAT is often called non-shivering thermogenesis (NST) BAT thermogenesis is triggered by the release of norepinephrine from its sympathetic nerve terminals, stimulating β3-adrenoceptors that turns on a cascade of intracellular events ending in activation of uncoupling protein-1 (UCP-1). It express an important protein called thermogenin that inserts into the inner mitochondria membrane and stimulates the rate of mitochondrial respiration that results in heat production. The molecular mechanism is not fully elucidate. Recent research elucidated novel thermogenic mechanisms that contribute to cold-induced thermogenesis both in BAT and beige adipose tissue and in muscle. The recent recognition of BAT in normal adult humans suggests a potential target for stimulation of energy expenditure by BAT to help mitigate increased body fat storage. Targeting thermogenesis in adipose tissue and muscle might be a promising therapeutic tool against obesity and associated metabolic diseases.

A healthy elastic artery ________. a. is compliant b. is a resistance artery c. reduces blood flow d. has a thin wall and irregular lumen

is compliant

the closed circulatory system evolved multiple times in animals

it's believed that animals evolved from flagellated protists and early in the evolution of animals, the circulatory system began to serve a respiratory function. In vertebrates, the principal differences in the blood vascular system involve the gradual separation of the heart into two separate pumps, as vertebrates evolved from aquatic life, with gills breathing to fully terrestrial life with lung breathing.

Nitric oxide is broken down very quickly after its release. Why?

nitric oxide causes vasodilation which increases blood flow to certain areas

Piloerection

reduces heat loss. Hair and feathers act as insulation for endotherms. The animals can regulate heat loss by hanging the orientation of the hair as occurs in mammals. When the erector muscle contracts (that is a smooth muscle that connects each hair follicle to the undersurface of the epidermis), the hair is pulled perpendicular in a process called piloerection so the fur offers better insulation. This happens mostly in dogs (like in the figure).

The Bohr Effect

reduction in O2 affinity caused by a decrease in pH and/or an increase in CO2 partial pressure. The Bohr Effect typically enhances O2 delivery, because it promotes O2 uploading in systemic tissues, while promoting loading in the breathing organs.

central pattern generators

rhythmically firing neurons in the CNS that initiate ventilation in animals. In vertebrates are located within the medulla of the brain.

Annelids circulatory system

some annelids have an open circulatory system but the majority have closed circulatory system

the relationship between the mammalian circulatory and the lymphatic system

some fluid leaves the capillaries and enters in the lymphatic system and now is called lymph, that travels through the lymph nodes and into the lymphatic ducts, and then comes back into the blood through the veins. The lymphatic system has valves to allow the flow unidirectional. So we can see here that goes parallel with the blood circulation.

A patient arrives in the emergency department with a blood pressure of 70/45 confused and complaining of thirst. Why?

soon

tunica intima, media, externa

the 3 coats of the major blood vessels The tunica intima is composed of epithelial and connective tissue layers. -Lining the tunica intima is the specialized epithelium called the endothelium, which is continuous throughout the entire vascular system, including the lining of the chambers of the heart. -Damage to these endothelial lining, an exposure of blood to the collagenous fibers beneath, is one of the primary causes of clot formation. -The endothelium releases local chemicals called endothelins, that can constrict the smooth muscle within the walls of the vessel to increase blood pressure. -Uncompensated overproduction of endothelins may contribute to hypertension, (high blood pressure), and may also contribute to cardiovascular disease. The tunica media is the substantial middle layer of the vessel wall. -It is generally the thickest layer in arteries, and it is much thicker in arteries than in veins. -The tunica media consists of layers of smooth muscle supported by connective tissue that is primarily made of elastic fibers, most of which are arranged in circular sheets. The outer tunica, tunica externa, is a substantial sheath of connective tissue composed primarily of collagenous fibers. -Some bands of elastic fibers are found here as well. -The tunica externa in veins, also contains groups of smooth muscle fibers. -This is normally the thickest tunic in veins.

Angiogenesis

the growth of blood vessels from existing vasculature It occurs throughout life in both health and disease, beginning in the utero, and continuing on through old age. Oxygen plays such a pivotal role in this regulation. Hemodynamic factors are critical for survival of vascular network, and for structural adaptations of vessel walls. Angiogenesis is controlled by both activator the inhibitory molecules that influence the rate of growth and division of vascular endothelial cells. Under normal circumstances, inhibitory factors are dominant. Angiogenesis begins when cells in the region where the blood vessels will develop, secrete angiogenic growth factors, that bind to receptors on the endothelial cells of existing blood vessels, this activates a signal transduction pathway that causes the epithelium to proliferate. Stimulation of angiogenesis can be therapeutic in ischemic heart disease, peripheral arterial disease, and wound healing. Decreasing or inhibiting angiogenesis can be therapeutic in cancer, ophthalmic conditions, rheumatoid arthritis, and other diseases. Exercise stimulate angiogenesis in skeletal muscle and heart. A lack of exercise leads to capillary regression. Capillaries grow in adipose tissue during weight gain and regress during weight loss.

neurogenic v myogenic

the invertebrates have a neurogenic heart, which requires nervous input to initiate contraction the vertebrate hearts are myogenic, this means that the cardiomyocytes can produce spontaneous rhythmic depolarization to initiate the contraction. Cardiomyocytes must be electrically coupled via gap junctions, so the depolarization in one cell can spread to adjacent cells, leading to coordinate contractions. The rate of depolarization varies among cardiomyocytes.

the epidemic of heart disease

the leading cause of death worldwide made worse by the fact that the adult mammalian heart is especially poor at repair. Damage to the mammal heart (such as that cause by myocardial infarction) leads to scarring, resulting in cardiac dysfunction and heart failure. In contrast, the hearts of fish and amphibians are capable of complete regeneration of cardiac tissue from multiple types of damage with full restoration of the functionality.

Hemoglobins

the most common and widespread respiratory pigments Virtually all vertebrates have blood hemoglobin. The blood-hemoglobin molecules of vertebrates are usually tetramers consisting (in adults) of two α-globin and two β-globin unit molecules; they always occur in red blood cells. Although many invertebrates also have hemoglobins in blood cells, some invertebrates have hemoglobins dissolved in their blood plasma. Hemoglobine increases the maximum amount of oxygen that blood can carry as much as 50 fold. The hemoglobin found in muscle is called myoglobin and the related protein in neuron is called neuroglobin. Neuroglobin protects neural tissue during periods of hypoxia (low oxygen). There is another recently discovered protein called cytoglobin found in connective tissue.

pressure is different in the different parts of the circulatory system

the pressure in the left ventricle changes significantly during ventricular systole, the ventricular pressure is very high and very low during ventricular diastole. And this happens because the high blood pressure pushes blood out into the aorta. The aorta keeps the pressure relatively constant, It has low resistance, and the pressure is kept high as blood is traveling throughout. The arterioles have higher resistance than the rest of the vasculature, because are narrow and offer resistance, then the pressure starts to drop and the minimum pressure is found in veins, by the time the blood returns to the heart.

Pressure changes in the heart and arteries of mammals

the pressure is higher in the left side of the heart, and mostly in the left ventricle Phases of the Cardiac Cycle: Isovolumetric ventricular contraction (a-b): This phase marks the beginning of systole and the closure of the AV valves at point (a). Rapid ejection (b-c): As the semilunar valves open at point (b), there is a rapid ejection of blood due to increased ventricular contractility. Reduced ejection (c-d): This phase marks the beginning of ventricular Repolarization leads to a rapid decline in ventricular pressures. Isovolumetric relaxation (d-e): When the ventricular pressures drop below the diastolic aortic and pulmonary pressures, the aortic and pulmonary valves close producing the second heart sound (point d). This marks the beginning of diastole. Ventricular filling (e-a): As the AV valves open at point (e), ventricular filling starts. The initial rapid filling is mainly augmented by ventricular Atrial contraction: Finally, near the end of ventricular diastole, the atrial contraction contributes about 10% of the ventricular filling volume.

Vasomotor response

the regulation of the blood flowing into the vasculature. The venous plexus, is a network of capillary beds under the skin, and there are connections between veins and arteries called arteriovenous anastomoses. When blood travels close to the surface the heat is loss across the skin, and when temperatures are low, the blood goes from the artery to the vein so doesn't go close to the surface to prevent heat loss, but when the temperature is higher, shunts are constricted and blood goes closer to the skin surface to dissipate heat. The changes in vascular smoot muscle tone are controlled by the posterior hypothalamus.

Action potentials in cardiomyocytes

the resting membrane potential of cardiomyocyte is roughly minus 90 millivolts, and during full depolarization, the membrane potential reaches +20 millivolts. The cardiac action potential can be divided into three basic phases: Rapid depolarization, a plateau, and a rapid repolarization. Rapid depolarization is characterized by a rapid shift in membrane potentials from minus 90 millivolts to roughly +20 millivolts, a plateau phase, characterized by a sustained membrane potential of roughly +10 milivolts, and a rapid repolarization, characterized by a rapid shift in the membrane potential back to negative 90 millivolts. Importantly, the plateau phase is unique to the cardiac action potential, and it's not found in that of skeletal muscle. This plateau phase is critical for connecting the cardiac myocyte action potential to cardiomyocyte contraction. three basic ion channels are responsible for the cardiac action potential: 1. A fast voltage gated sodium channel; opening or fast sodium channels, that are responsible for the initial, rapid depolarization of the cardiomyocyte, These sodium channels allow for a rapid influx of positive sodium ions into the cell, which depolarize the membrane potential with incredible quick kinetics. However, these channels also quickly close and eliminate the sodium influx soon after maximum depolarization of +20 millivolts is achieved. 2. variable potassium channel: The cardiomyocyte potassium channels are induced to open following rapid depolarization and allow egress of positively charged potassium from the cell, which is responsible for the cell's eventual repolarization. However, these potassium channels initially display low potassium conductance, which increases gradually but slowly. This variable conductance is partially responsible for the unique plateau phase of the cardiomyocyte action potential. The initially low potassium conductance only allows for a partial repolarization of the membrane, making possible the plateau phase. However, as the potassium conductance builds, it overwhelms all other ion conductance and thus causes the rapid repolarization phase. 3. slow calcium channels; the cardiomyocytes uniquely posses a type of slow calcium channel known as the long L-type calcium channel. These calcium channels are slow to open following the rapid depolarization phase but remain open for a long time afterwards. Opening of the L-type calcium channel causes an influx of calcium into the cardiomyocyte, which initiates cardiac excitation-contraction coupling. This slow calcium channels are most responsible for the plateau phase because they allow a long time-scale influx of positive ions, which exactly balances the initial low efflux of potassium. The balance between calcium influx and low potassium efflux is ultimately the basis of the sustained positive membrane potential observed in the plateau phase. Eventually however, this low calcium channels close and the potassium channels continue to open, resulting in the rapid repolarization phase.

Platelets

they are small cell fragments called platelets (thrombocytes) and are attracted to the wound site when they adhere by extending many projections and releasing their contents. This contain activates other platelets, and also interact with other coagulation factors which convert fibrinogen, a water soluble protein present in blood serum into fibrin, a non-water soluble protein, causing the blood to clot. Many of the clotting factors require vitamin K in order to work. Vitamin K deficiency can lead to problems with blood clotting. Many platelets converge and stick together at the wound site forming a platelet plug, also called a fibrin clot. Platelets are formed from the disintegration of larger cells called megakariocytes. Each platelet is shape, and two to four micron in diameter. They contain many small vesicles, but do not contain a nucleus.

antifreeze proteins

to survive extreme cold, some animals have antifreeze macromolecules (proteins or glycoproteins) that reduce the freezing point of the body fluids, disrupting the ice crystal formation by binding to the surface of small ice crystals to prevent their growth. We can see in the figure that the anti -freeze protein binds to ice crystals so the ice crystals stop growing. They are present in many fish and invertebrates to prevent them freezing in cold weather or cold water.

velocity is different in the different parts of the circulatory system

velocity is greatest in the arteries and veins, and lowest in the capillaries. Since the blood velocity equals the blood flow divided by the total cross sectional area of the vessel in any given portion of the circulatory system, so the vasculature has the lowest velocity because it has the highest cross sectional area. This is very important since this is the site of nutrient exchange and you want blood to slow down to allow proper exchange.

Air-breathing fish

ventilate their breathing organs using a buccal force pump similar to those of other fishes. Some species rely predominantly on water breathing with gills and only supplement gas exchange with air breathing when adverse respiratory qualities in the water make aquatic breeding insufficient or too costly for extraction of the required required oxygen. Others obligate air breathers succumb if denied access to air for a short time. Most air breathing fishes are teleost. Lung fishes have the most highly developed air-breathing organ in any fish. These lungs are highly complex, covered in folds that increase the surface area Lung fish separates oxygenated blood coming from the pulmonary system, and de-oxygenated blood coming from the tissues. They ventilate their breathing organs using a buccal force pump similar to those of other fishes simply swallowing air. the ventilatory cycle of an air-breathing fish- they have to go to the surface and the air comes into the mouth, they expand the buccal cavity, and with a series of chambers the air goes inside.