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In insects, arthropods, and most molluscs, blood bathes the organs directly in an open circulatory system. In open circulatory systems there is no distinction between blood and interstitial fluid, and this general body fluid is called hemolymph.
Both systems have three basic components:
- A circulatory fluid (blood or hemolymph)
- A set of tubes (Blood vesseld)
- A muscular pump (heart)
Closed: more effecient at transporting circulatory fluid to tissues and cells. Relatively high blood pressures which enable the effective deliver of 02 and nutrients to the cells of larger animals
Open: lower hydrostatic pressures maing them less costly than closed systems in terms of expenditure.
Arteries: branch into arterioles and carry blood to capillaries.
Arterioles: small vessels that cconvey blood to the capillaries.
Capillaries: microscopic vessels that have very thin, porous walls
network of capillaries is called capillary beds which infiltrate each tissue, and across these thin walls of capillaries chemicals such as dissolved gases are excahgned by diffusion between the blood and the interstial fluid around the tissue cells
Veins: blood vessels that carry blood TOWARDS the heart.
Venules: converge into veins and return blood from the capillaries to the heart.
Vertebrate hearts contain two or more chambers
Blood enters through an atrium and is pumped out through a ventricle.
Atria: chambers that receive blood entering the heart
Ventricle: chambers responsible for pumping blood out of the heart.
In reptiles and mammals, oxygen poor blood flows though the pulmonary circuit to pick up oxygen through the lungs.
In amphibians, oxygen poor blood flows through a pulmocutaneous circuit to pick up oxygen through the lungs and skin.
i.e. humans and birds have two atria and two ventricles. A powerful four chambered heart is a key adaptation that supports the endothermic way of life because endotherms use about ten times as much energy as equal sized ectotherms.
i.e. bony fish, rays, and shark have a heart consisting of two chambers (1 atrium and 1 ventricle). The blood passes through the heart once in each complete circuit and this system is called single circulation. Contraction of the venticle pumps blood to the gills where there is an exchange of gas and as the blood leaves the gills the capillaries converge into a vessel that carries oxygen-rich blood to capillar beds throughout the body, then the blood returns to the heart once more.
Lower: i.e. amphibians have three chambers (2 atria and 1 ventricle) and two systems: pulmocutatenous circuit (delivers oxygen poor blood to the cpaillary beds of the gas exchange tissues that are in both lungs and skin and oxygen rich blood back to heart) and systemic circuit (delivers oxygen rich blood to capillary beds in organs and tissues and returns to heart).
Lower: i.e. reptiles have three chambers (2 atria and 1 ventricle, but the ventricle is partially divided by a septum). It has two systems: pulmonary (delivers oxygen poor blood to capillary beds of gas exchange tissues in lung and delivers oxygen rich blood back to heart) and systemic (delivers oxygen rich blood to organs and other tissues and then brings back oxygen poor blood to heart)
pulmonary circuit: delivers oxygen-poor blood to capillary beds in tissues of lung for gas exchange and then delivers oxygen-rich blood back to the heart.
systemic circuit: delivers oxygen-rich blood to capillary beds in tissues of organs and cells and then delivers the oxygen-poor blood back to the heart.
Fish hearts simply draw in deoxygenated blood in a single atrium, and pump it out through a ventricle. This system is termed "single circulation", as blood enters the heart, gets pumped through the gills and out to the body, Blood pressure is low for oxygenated blood leaving the gills. 3 and 4 chambered hearts have a pulmonary circuit (pathways taking blood from heart to lung and back to heart) and must be set up such that blood can travel from the heart to become oxygenated in the lungs and then be properly pumped back the heart and out to the body.
1. contraction of the right ventricle pumps blood to the lungs through the pulmonary arteries.
2. as the blood flows through the cpaillary beds in the left and right lungs it loads O2 and unloads CO2.
3. oxygen rich blood returns from the lungs through the pulmonary veins to the left atrium of the heart.
4. oxygen rich blood flows into the left ventricle
5. left ventricle pumps oxygen rich blood to body tissues through systemic circuit which starts with the aorta
Distinguish between low-density lipoproteins (LDLs) and high-density lipoproteins (HDLs).
LDLs: often called "bad cholesterol" is associated with the deposition of cholesterol in artieral plaques.
HDLs: often called "good cholesterol" appears to reduce the deposition of cholesterol.
Exercise decreases LDL/HDL ratio. smoking and consumption of certain processed vegetable oils called trans fats increase the LDL/HDL ratio.
6. aorta conveys blood to arteries leading throughout the body, starting with the coronary arteries which supply blood to the heart muscle itself.
7. then it branches to cpillary beds in the head and arms (forelimbs) and then the abdomen .
8. within these capillaries there is net diffusion of O2 from the blood to the tissues and of CO2 produced by cellular respiration into the blood.
9. capillaries then rejoin into venules which convey blood to veins.
10. oxygen poor blood from head, neck and forelimbs' tissues channel into a large vein called the superior vena cava while oxygen poor blood from the trunk and hind limbs drain into the inferior vena cava.
11. the two venae cavae empty the oxygen poor blood into the right atrium
12. the oxygen poor blood empties into the right ventricle and then it pumps it into the pulmonary arteries to the lungs.... again.
The right atrium contracts and the deoxygenated blood empties into the right ventricle and the right atrioventricular (AV) valve prevents the blood from going back into the right atrium. (FIRST HEART SOUND "LUB" )
The right ventricle then contracts and pumps the deoxygenated blood through the right semilunar valve (by pushing it open with pressure) into the pulmonary artery. The pressure of the blood built in the pulmonary artery closes the semilunar valves as the right ventricle relaxes to prevent backflow of blood (SECOND HEART SOUNDS "DUB").
cardiac cycle: one complete sequence of pumping and filling of blood
systole: the contraction phase
diastole: the relaxation phase
first sound: from the recoil of blood against the closed AV valves
second sound: from the recoil of blood against the closed semilunar valves.
right AV valve: between right atrium and right ventricle. prevents backflow of deoxygenated blood into right atrium from right ventricle.
right semilunar valve: between right ventricle and pulmonary artery. prevents backflow of deoxygenated blood into right ventricle from pulmonary artery.
left AV valve: between left atrium and left ventricle. prevents backflow of oxygenated blood into left
atrium from left ventricle.
left semilunar vlave: between left ventricle and aorta. prevents backflow of oxygenated blood from aorta into left ventricle.
This group of autorhythmic cells are located int he wall of the right atrium, near where the superior vena cava enters the heart.
Its function is to set the rate and timing at which all cardiac muscle cells contract.
1. impulses form SA node first spread rapidly through the walls of the atria, causing both atria to contract in unison.
2. during atrial contraction, the impulses originating at the SA node reach other autorhythmic cells that are located int he wall between the left and right atria called AV or atrioventricular node.
3. the impulses are delayed for about .1 second before spreading to the walls of the ventricles. (this delay allows atria to empty completely before the ventricles contract)
4. the singla sfrom the AV node are conducted throughout the ventricular walls by specialized muscle fibers called bundle branches and Purkinje fibers.
nerves: there are two sets of nerves, the sympathetic and parasympathetic nerves. The symphathetic nerves increase your heart rate and the parasympathetic nerves decrease your hear rate.
hormones: epinephrine secreted by teh adrenal glands increases the heart rate.
body temperature: an increase of only 1 degree Celsius increases the heart rate of about 10 beats per minute (this is why your hear beat is faster when you have a fever).
exercise: increases heart rate. Your body needs oxygen in order to efficiently break down glucose and process it into your cell's primary energy source (ATP). As you do more intense exercise, you need more energy and therefore more oxygen. Your blood carries oxygen from the lungs to your muscles. To keep up with these increased oxygen needs, you have to have more blood going to your muscles. As a result, your heart pumps faster, sending more oxygenated blood to your muscles per second.
capillaries: smallest blood vessels (diameter slightly greater than that of a red blood cell), thin walls (just endothelium and basal lamina). This structure helps exchange of substances between the blood in cpaillaries and the interstitial fluid.
arteries: have two layers of tissue surrounding the endothelium (an outer layer of connective tissue containing elastic fibers which allow the vessel to stretch and recoil and a middle layer containing smooth muscle and more elastic fibers. has a wall three times as thick as that of a vein. the thicker walls of arteries are very strong accommodating blood pumped at high pressure by the heart, and their elastic recoil helps maintain BP when the heart relaxes between contractions.
veins: have two layers of tissue surrounding the endothelium (an outer layer of connective tissue containing elastic fibers which allow the vessel to stretch and recoil and a middle layer containing smooth muscle and more elastic fibers. Has thinner walls than arteries because they convey blood back to the heart at alower velocity and pressure. Valves in the veins maintain an unidirectional flow of blood.
Explain why blood flow through capillaries is substantially slower than blood flow through arteries and veins.
When you have a big hose and then a narrow hose attached to it, the velocity INCREASES in the narrow hose but in the capillaries the speed DECREASES. the number of cpaillaries is enormous. Each artery conveys blood to so many capillaries that the TOTAL cross sectional area is much greater in capillary beds than in the arteries or any other part of the circulatory system.
Explain why blood flow through capillaries is substantially slower than blood flow through arteries and veins. 2
Results in A dramatic decrease in velocity from the arteries to the capillaries: 500 times slower (0.1 cm/sec) than in the aorta (48cm/sec). This is very important because capillaries have extremely thin walls to permit transfer of substances between blood and interstitial fluid.
Arterial BP is highest when the heart contracts during ventricular systole. The pressure at this time is called systolic pressure, the spikes in BP is caused by the powerful contractions of the ventricles stretch the arteries. When the heart contracts blood enters the arteries faster than it can leave and te vessels stretch from the rise in pressure, during diastole the elastic walls of the arteries snap back which maintains a substantial blood pressure (diastolic pressure).
Before enough blood has flowed into the arterioles to completely relieve pressure in the arteries, the heart contracts again. This maintenance of constant presence of pressure in the artieries is important because it alllows blood to continuously flow into arterioles and capillaries.
Blood pressure: The force of blood or the pressure pushing against blood vessel walls.
Measured through: During each heartbeat, BP varies between a maximum (systolic) and a minimum (diastolic) pressure. Blood pressure is generally measured for an artery in the arm at the same height as the heart. A sphygmomanometer, an inflatable cuff attached to a pressure gauge, measures blood pressure in an artery.
1. The cuff is inflated until the pressure closes the arter, so that no blood flows past the cuff, when this occurs the pressure exerted by the cuff exceeds the pressure in the artery.
2. the cuff is allowed to deflate gradually. when the pressure exerted by the cuff falls just below that in the artery, blood pulses in to the forearm generating sounds that can be heared with the stethoscope. the pressure measured at this point is the systolic pressure.
3. the cuff is allowed to deflate further, just until the blood flows freely through the artery and the sounds below the cuff disappear. the pressure at this point is the diastolic pressure.
Explain the interrelationship between cross-sectional area of blood vessels, blood flow velocity, and blood pressure.
increase in cross sectional area of blood vessels= decrease in blood flow velocity = decrease in BP
P=V*A P/V=A V=P/A
cardiac output: the volume of blood pumped per minute by each ventricle of the heart.
two factors that influence cardiac output:
1. the rate of contraction or heart rate (number of beats per minute)
2. stroke volume or the amount of blood pumped by a ventricle in a single contraction (avg stroke volume in humans is about 70mL)
Explain how blood returns to the heart, even though it must sometimes travel from the lower extremities against gravity (3 mechanisms).
Blood returns to the heart even against gravity through 3 mechanisms:
1. rhythmic contractions of smooth muscles in the walls of venules and veins aid in the movement of the blood.
2. the contraction of skeletal muscles during exercise squeezes blood through the veins toward the heart.
3. change in pressure within the thoracic cavity durin inhalation cuases the venae cavae and other large veins near the heart to expand and fill with blood.
1. contraction of the smooth muscle in the wall of an arteriole which reduces the vessel's diameter and decreases blood flow to the adjoining capillary beds. When the smooth muscle relaxes, the arterioles dilate, allowing blood to enter the capillaries.
2. the action of precapillary sphincters or rings of smooth muscle located at the entrance to cpaillary beds. the singla that regulat blood flow include nerve impulses, hormones, and chemicals produced locally.
Explain how osmotic pressure and hydrostatic pressure regulate the exchange of fluid and solutes across capillary walls.
The presence of blood proteins tend to pull fluid back into the capillaries. This is because proteins (especially albumin) create an osmotic pressure difference between the capillary interior and the interstitial fluid. In places where the BP is greater than the osmotic pressure difference there is a net loss of fluid from the capillaries. Where osmotic pressure difference exceeds the BP there is s net movemetn of fluid from the tissues into the capillaries.
Describe the composition of lymph and explain how the lymphatic system helps the normal functioning of the circulatory system.
lymph: the composition of lymph is about the same as that of interstitial fluid and it is the fluid that is lost from capillaries which also includes some leakage of blood proteins that has been returned to the blood via the lymphatic system. Once it has entered the lymphatic system by diffusion it is called lymph.
Describe the composition of lymph and explain how the lymphatic system helps the normal functioning of the circulatory system. 2
The lymphatic system aids the immune system in destroying pathogens and filtering waste so that the lymph can be safely returned to the circulatory system.To remove excess fluid, waste, debris, dead blood cells, pathogens, cancer cells, and toxins from these cells and the tissue spaces between them.
Describe the composition of lymph and explain how the lymphatic system helps the normal functioning of the circulatory system. 3
The lymphatic system also works with the circulatory system to deliver nutrients, oxygen, and hormones from the blood to the cells that make up the tissues of the body. Important protein molecules are created by cells in the tissues. Because these molecules are too large to enter the capillaries of the circulatory system, these protein molecules must be transported by the lymph to the bloodstream at the terminus.
Plasma is composed of 90% water, inorganic salts or blood electrolytes, plasma proteins, nutrients, metabolic wastes, respiratory gases, and hormones.
The inorganic salts are very important because they buffer the blood, maintain osmotic balance of the blood, and directly affects the composition of the interstitiaul fluid.
Plasma proteins act as buffers against pH changes, help maintain osmotic balance between blood and interstitial fluid, and contribute to the blood's viscosity (or thickness). The immunoglobulins, or antibodies (a type of plasma protein) combats viruses and other foreign agents that invade the body.
Others escort lipids because lipids cannot travel in blood without being bound to a protein. A third group of plasma proteins called fibinogen act as clotting factors that help plug leaks when blood vessels are injured.
erthryocytes or red blood cells are small disks (7-8 micrometers in diameter) and are bioconcave (thinner in the center than at the edges). This shape increases surface area, enhancing the rate of diffusion of O2 across their plasma membranes. Mature mammalian erythrocytes lack nuclei. This unusual characteristic leaves more space in these tiny cells for hemoglobin (iron-containing protein that transports O2).
Erthyrocytes also lack mitochondria and generate their ATP exclusively by anaerobic metabolism. This is important because oxygen transport would be less efficient if erthrocytes were aerobic and consumed some of the O2 they carry. One erythrocyte can carry about a billion O2 molecules because it can contain about 250 million molecules of hemoglobin (each hemoglobin carries 4 molecules of O2).
leukocytes or white blood cells come in five types. Some are phagocytic, engulfing and digesting microorganisms as well as debris from the body's own dead cells. Others called lymphocytes develop into specialized B cells and T cells that mount immune responses against foregin substances. Unlike erythrocytes, leukocytes are also found outside the circulatory system, patrolling both interstitial fluid and lymphatic system.
Describe the function of platelets. Outline the sequence of events that occurs during blood clotting.
platelets are pinched off cytoplasmic fragments of specialized bone marrow cells. They serve both structural and molecular functions in blood clotting.
1. clotting begins when endothelium of a vessel is damaged, exposing connective tissue in vessel wall to
2. platelets adhere to collagen fibers int he connective tissue and release substance that makes nearby platelets sticky.
3. the platelets form a plug that provides emergy protection against blood loss.
Describe the function of platelets. Outline the sequence of events that occurs during blood clotting. 2
4. this seal is reinforced by a clot of fibrin when vessel damage if severe.
5. fibrin is formed via this process:
a. clotting factors released from clumped platelets or damaged cells mix with clotting factors in plasma forming an activation cascade that converts a plasma protein called prothrombin to its active form thrombin.
b. thrombin itself is an enzyme that catalyzes the final step of the clotting process: the conversion of fibrinogen to fibrin.
c. the threads of fibrin become interwoven into a clot.
Outline the formation of erythrocytes from their origin from stem cells in the red marrow of bones to their destruction by phagocytotic cells. /
Describe the hormonal control of erythrocyte production.
stem cells located in red marrow bones produce blood cells (particularly in ribs, vertebrae, sternum, and pelvis). there is a negative feedback mechanism that controls erythrocyte production depending on the amount of O2. If tissues do not receive enough O2, the kidneys synthesize and secrete a hormone called erythropoietin (EPO) that stimulates erythrocyte production.
Outline the formation of erythrocytes from their origin from stem cells in the red marrow of bones to their destruction by phagocytotic cells. 2 /
Describe the hormonal control of erythrocyte production.
If th bood is delivering more O2 than the tissues can use, the level of EPO falls and erythrocyte production slows. Erythrocytes circulate for only 3-4 months before being replaced; the old cells are consumed by phagocytic cells in the liver and spleen. The production of new erythrocytes involves recycling of materials such as the use of iron scavneged from old erythrocytes in new hemoglobin molecules.
Distinguish between heart attack and stroke
a heart attack, also called myocardial infarction, is the damage or death of cardiac muscle tissue resulting form blockage of one or more coronary arteries.
a stroke is the death of nervous tissue in the brain due to lack of oxygen.
Compare the hearts of vertebrates with double circulation to those of vertebrates with a single circuit.
The 3 and 4 chambered heart has "double circulation"."Double circulation" has an interior circuit within the heart--blood enters the heart, leaves the heart and gets oxygenated, enters the heart again, and then gets pumped out to the body. Because "Double circulation" allows oxygenated blood to be pumped back into the heart before going out to the body, it pumps blood with much more pressure and much more vigorously than "single circulation".
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