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167 Cards in this Set
- Front
- Back
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what are the general functions of the circulatory system? |
1. transportation- respiratory gases, nutrients and wastes 2. regulation- hormonal and temperature 3. protection- clotting and immune |
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what are the components of the circulatory system? |
1. cardiovascular system: - heart= 4 chambered pump - blood vessels= arteries, arterioles, capillaries, vanules and veins
2. lymphatic system- lymphatic vessles, lymphoid tissues, and lymphatic organs such as spleen, thymus, tonsils and lymph nodes - IS A COLLECTING SYSTEM: collects things that don't get back to the body |
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what are the two components that make up the composition of blood? |
1. PLASMA (55%)- is the fluid part of blood - is the liquid portion of blood and everything that is dissolved in it - consists of plasma proteins and serum
2. FORMED ELEMENTS (45%)- are types of cells in the blood such as red blood cells |
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what is the composition of the plasma in blood? |
1. nutrients and metabolites- glucose, fatty acids, etc... 2. hormones- insulin, glucagon, sex hormones 3. ions- K+, Ca2++, Mg++ 4. bicarbonate 5. respiratory gasses such as oxygen and CO2 6. waste products |
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what is the major ion in the blood plasma? |
Na+ |
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what is an important buffer in blood plasma? |
bicarbonate---keeps blood at ph 7.35 |
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what 3 types of plasma proteins make up the composition of blood plasma? |
1. ALBUMIN- accounts for 60-80%(major protein) - creates colloid osmotic pressure that draws water from interstitial fluid into capilaries to maintain blood volume and pressure; gets water to move where we want it to go 2. GLOBULINS- transporters of lipids - alpha and beta = transport lipid soluble molec - gamma = antibodies 3. fibrinogen- soluble protein that functions in clotting - is converted to fibrin, an insolule protein polymer - serum = fluid left when blood clots (plasma minus fibrinogen)
*proteins= extracellular and dissolved in blood |
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what make up the composition of the formed elements in the blood? |
1. ERYTHROCYTES (red blood cells) - biconcave: shape is critical to function -carries oxygen and LACKS NUCLEI & MITOCHONDRIA - contains hemoglobin and tranferrin 2. PLATELETS (thrombocytes) - smallest formed element - lack nuclei - clot blood and need fibrinogen |
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what is hematopoiesis? |
- is the formation of blood cells from stem cells in the bone marrow and lymphoid tissue |
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what is erythropoiesis? |
- is the formation of RBC - stimulated by erthropoietin from kidney - old RBCs removed from blood by phagocytic cells in the liver, spleen and bone marro - iron is recycled back into Hb production |
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what is leukopoiesis? |
- is the formation of white blood cells - stimulated by variety of cytokines = autocrine regulators secreted by immune system |
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what is the general process of blood clotting? |
hemotasis- cessation of bleeding when a blood vessel is damaged - process turns liquid blood into solid (gel) by converting soluble protein (fibrinogen) into insoluble protein (fibrin) - damage exposes collagen fibers to blood, producing: 1. vasoconstriction- blood vessel goes to smaller diameter 2. fomration of platelet plug 3. formation of fibrin protein web- stops bleeding |
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what occurs with blood clotting and platelets? |
- platelets= active components of clotting and important b/c doesn't cause clotting when there's no injury - platelets don't stick to intact endothelium because of presence of prostacyclin and nitic oxide, which keeps clots from forming and are vasodilators - also the removal of ADP by CD39 |
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what is the process of blood clotting and platelets? |
- damage to endothelium allos platelets to bind to exposed collagen...von Wilebrand factor increases bond by binding to both collagen and platelets...platelets stick to collagen and release ADP, seratonin, and thromboxane A2= platelet release reaction
- seratonin and thromboxane A2 stimulate vasoconstrictio, reducing blood flow to wound - other chemicals cause other platelets to become sticky and attach and undergo platelet release reaction - this aggregation continues until PLATELET PLUG is formed |
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how is fibrin important for blood clotting? |
- fibrinogen turns fibrin and forms meshwork around platelets - calcium and phospholipids convert prothrombin to the active enzyme thrombin, which converts fibrinogen to fibrin - conversion of prothrombin to thrombin is done by Factor X - how Factor X is controlled depends on the nature of the clotting reaction |
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how is fibrinogen converted to fibrin for blood clotting? |
1. INTRINSIC PATHWAY- activated by exposure to negatively charges surface when there's injury - collagen... activation of cascade reaction of other blood factors... ultimately factor X is activated - occurs slower than extrinsic pathway 2. EXTRINSIC PATHWAY- is a shorter pathway - initiated by thromboplaastin, only present in tissue...clotting of blood that enters tissue due to injury...thromboplastin directly activates factor X - this pathway indicates MORE SERIOUS type of damage |
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what is the similarities and differences of the two pathways of fibrin formation? |
SIMILARITIES: - pathway occurs the same once Factor X is activated
DIFFERENCES: - intrinsic goes through cascade and extrinsic doesn't - extrinsic= damage to tissue outside vessel - intrinsic= damage to blood vessel in general |
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what is the role of fibrin? |
- once fibrin network is established, the clot now contains platelets, fibrin and trapped RBCs - platelet plug undergoes plug contraction to form more compact structure - physical restructuring of platelets - actin contraction...analogous to smooth muscle contraction |
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what are anticoagulants? |
clotting can be prevented with certain drugs: - calcium chelators - heparin: blocks thrombin (which is required for fibrinogen to be converted into fibrin) |
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what is the function of the right atrium? |
receives DEOXYGENATED blood from the body |
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function of left atrium? |
receives OXYGENATED blood from the lungs |
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function of right ventricle? |
pumps DEOXYGENATED blood to the lungs |
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function of left ventricle? |
pumps OXYGENATED blood to the body |
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what is the fibrous skeleton? |
- is a dense collection of connective tissue - separates atria from ventricles, which make atria work as one unit and the ventricles work as a separate unit - forms the annuli fibrosi which hold in heart valves |
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how many systems does the heart use to for continuous pumping of blood? |
use 2 independent systems: pulmonary and systemic circuit |
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pulmonary circuit? |
- is between the heart and lungs - blood pumps to lungs via pulmonary arteries - blood returns to heart via pulmonary veins |
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systemic circuit? |
- is between the heart and body tissues - blood pumps to body tissues via aorta - blood returns to heart via superior and inferior venae cavae |
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is resistance in systemic circuit greater or lesser than in the pulmonary circuit? |
resistance in systemic > pulmonary - amount of work done by left ventrivle pumping to systemic is greater, causing left ventricle to be more muscular |
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what are the atrioventricular valves (AV)? |
- ARE LOCATED BETWEEN THE ATRIA AND THE VENTRICLES - includes the tricuspid= between right atriu and ventricle - includes bicuspid= between left atrium and ventricle |
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what are the semilunar valves? |
- are located between the ventricles and arteries leaving the heart - pulmonary= between right ventricle and pulmonary trunk - aortic= between left ventricle and aorta |
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what is the importance of the valves in the heart? |
- promotes one direction of blood flow - opening and closing of valves results from pressure differences - high pressure of ventricular contraction is prevented from inverting AV valves by contraction of papillary muscles which are connected to AVs by chorda tendinea |
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what are the three cell layers of the heart wall? |
1. ENDOCARDIUM= epithelial tissue 2. MYOCARDIUM= cardiac muscle 3. EPICARDIUM= thin covering of outer surface
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what is the pericardial sac? |
- anchors the heart - is a double layer - secretes pericardial fluid, which reduces friction. |
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what is the importance of myocardium? |
- myocardium is a mass of muscle cells connected to each other through gap junctions - APs that occur at any cell in a myocardium can STIMULATE ALL THE CELLS IN THE MYOCARDIUM - IT BEHAVES AS A SINGLE FUNCTIONAL UNIT - atria of heart composes one myocardium, and ventricles of heart compose another myocardium |
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what is autorhythmicity? |
- is a mass of muscles that can operate on its own and produces its own APs. - autorhythmic cells= special cardiomyocytes that initiate and conduct APs on their own |
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what is the sinoatrial (SA) nodes? |
"pacemaker" located in RIGHT ATRIUM - is where the heartbeat typically starts pacemaker potential= slow, spontaneous depolarization |
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how are voltage-gated Ca2+ channels and K+ channels relate to electrical activity of the heart? |
these channels keep a constant flow of membrane potential and don't require any stimulus unlike neurons |
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what are the function of pacemaker cells in sinoatrial node? |
- they depolarize spontaneously, but the rate at which they do so can be modulated - parasympathetic NS slows heart rate - sympathetic nervous system (noreminephrine and epinephrine) increase heart rate VAGUS NERVE= normally regulating heart rate |
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charactertistics of myocardial APs? |
- cardiac muscle cells have resting potential of -90mV - are depolarized to threshold by action potentials from SA node |
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calcium channels in cardiac muscle? |
- unlike skeletal mucle, volatage gated calcium channels are not directly connected to calcium channels in the SR - calcium channels act as second messenget to open SR channels called calcium-induced calcium release - excitation-contraction coupling is slower due to timing of second messenger |
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p- wave of electrocardiogram |
atrial depolarization |
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QRS wave of electrocardiogram |
ventricular depolarization |
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S-T segment |
plateau phase |
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T wave |
ventriclular repolarization |
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systole |
CONTRACTION of heart muscles |
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diastole |
RELAXATION of heart muscles |
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what is the process of the cardiac cycle? |
1. ventricles begin contraction, pressure rises, and AV valves close (lub) 2. pressure builds, semilunar valves open (delivers blood into arteries) and blood is ejected into arteries 3. pressure in ventricles fall; semilunar valves close (dub) 4. pressure in ventricels fall below that of atria and AV valves opens. Ventricles fill 5. atria contract, sending last of blood to ventricles |
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LUB |
- occurs when AV valves close - occurs at ventricular systole - occurs AFTER THE QRS wave
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DUB |
- is the closing of semilunar valves and occurs at ventricular diastole - occurs at the BEGINNING of the T wave |
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what is a heart murmur? |
- abnormal heart sounds produced by abnormal blood flow through the heart. many are caused by defective heart valves |
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what is the parallel arrangement of blood flow? |
- allows organs to receive blood of same composition - blood flow through an organ system can be adjusted according to need - blood is constantly reconditioned - reconditioning organs such as digestive, kidney, and skin receive more blood than their own need - allows blood that leaves heart to go to all organs in body at the same time |
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what are the characteristics of arteries? |
- contain lots of elastin so is very elastic - expands during systole and recoils during diastole - helps maintain smooth blood flow during diastole |
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what are the characteristics of arterioles? |
- are small arteries and are muscular - they provide most resistance in the circulartory system b/c SA increases - can cause greatest pressure drop` |
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characteristics of capillaries? |
- are the smallest blood vessle - where gasses and nutrients are exchanged between the blood and tissues - no cell is more than 80um away from a capillary |
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exchange of fluid between capillaries and tissues |
- distribution of ECF between blood and intersitial compartments i in state of dynamic equilibrium - movement out of capillaries is driven by HYDROSTATIC PRESSURE exerted against capillary wall |
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characteristics of veins |
- contain majority of blood in circulartoy system - contains very low pressure which is insufficient to return blood to heart |
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what is venous return and how is it accomplished? |
- is when blood is moved toward the heart by contraction of surrounding skeletal muscles - is the return of blood to heart via veins - is dependent on blood volume and venous pressure, venoconstriction caused by sympathetic nervous system, skeletal muscle pumps, and pressure drops during inhalation |
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end diastolic volume? |
volume in the ventricles after filling from atrium |
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stroke volume |
blood pumped out of ventricle with each contraction
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cardiac output |
volume of blood pumped by heart per minute |
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what is the important function of lymphatic system? |
is the system that moves the 3 liters that don't return from capillary bed to veins |
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what creates an increase in blood pressure? |
increast in heart rate, stroke volume and peripheral resistance |
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how is cardiac output regulated? |
sympathoadrenal activity raises BP via arteriole vasoconstriction and by increased cardiac output - kidneys play a role in BP by regulating blood volume and thus stroke volume |
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what are the 3 general separate processes of repiration? |
1. ventilation- breathing 2. gas exchange- between blood and lungs and between blood and tissues 3. oxygen utilization by tissues to make ATP
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what is external respiration? |
ventilation and gas exchange in lungs |
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what is internal respiration? |
oxygen utilization and gas exchange in tissues |
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what respiratory structure increases SA and enhances out lungs? |
bronchi |
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what structure are the terminal alveoloar sacs located? |
in the respiratory zone (respiratory bronchioles) |
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what occurs during gas exchange in lungs? |
- occurs by diffusion - oxygen conc is higher in lungs that in the blood, so oxygen diffuses into the blood - carbon dioxide concentration in the blood is higher than in the lungs so it dffuses into the lungs |
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what is the importance of alveoli? |
- are air sacs in the lungs where gas exchange occurs!!
-- provides a large SA to increase diffusion rate |
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what is Type I of alveolar cells? |
- is where 95-97% total surface area where gas exchange occurs |
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what is Type II of alveolar cells? |
- secrete pulmonary SURFACTANT and reabsorb sodium and water, preventing fluid buildup and surface tention |
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What are macrophages? |
removes pathogens |
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define atmopheric pressure |
is the pressure of air outside the body (760 mmHg) |
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what is intrapulmonary pressure? |
- is pressure in the lungs - should be at about 760mmHg
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what is intrapleural pressure? |
is the pressure within the intrapleural space (between parietal and visceral pleura) - creates a positive force that keeps lungs expanded - is always at a lesser values than intrapulmonary pressure (< 760mmHg) |
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what is transpulmonary pressure? |
pressure difference between intrapulmonary and intrapleural pressures - keeps lungs adhering to thoracic wall and therefore functioning - lungs are actually much smaller than thoracic cavity |
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what is boyle's law? |
states that the pessure of a gas is inversely proportional to its volumes P= 1/V |
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in relation to boyle's law, what happens when there's an increase in lung volume? |
an increase in lung volume during inspiration DECREASES intrpulmonary pressure to subatomospheric levels, allowing air to go IN |
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in relation to boyle's law, what happens when there's a decrease in lung volume? |
a decrease in lung volume during exhalation INCREASES intrapulmonary pressure above atmospheric levels, allowing air to go OUT |
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what occurs during ventilation (breathing) |
- air movies from higher to lower pressure - pressure differences between the two ends of the conducting zone occur due to changing lung volumes - compliance, elasticity and surface tension are important physical properties of the lungs |
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what is surface tension? |
- contractive tendency of surface of a liquid that allows it to resist and external force - caused by cohesion of similar molecules, and is responsible for many of the behaviors of liquids - hydrogen bonding |
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Define the term compliance and explain how lung elasticity and surface tension can affect compliance. |
Compliance- How much effort is required to stretch the lungs and chest wall. The lungs normally have high compliance and expand easily because elastic fibers in lung tissue are easily stretched and surfactant in alveolar fluid reduces surface tension |
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Explain the process of surface tension in the alveoli of the lung and discuss how this is reduced by surfactant. |
A thin layer of alveolar fluid coats the luminal surface of alveoli and exerts a force known as surface tension. |
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what is Law of Laplace? |
the smaller something becomes the more pressure is going to be exerted by surface tension of water |
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what reduces surface tension? |
surfactant |
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what is the importance of surfactant? |
IT REDUCES SURFACE TENSION -is secreted by type II alveolar cells |
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How is oxygen transported in blood? |
by red blood cells! |
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what are the characteristics of RBCs? |
- have oxygen carrying protein called hemoglobin - have no nucleus or mitochondria |
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characteristics of hemoglobin |
- most oxygen in blood is bound to Hb - has 4 iron containing hemes - 1 Hb molecules can carry 4 oxygen molecules |
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what is anemia? |
is below normal hemoglobin levels, normal PO2 but total oxygen low in blood |
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what is polycythemia? |
above normal hemoglobin levels |
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what is erthropoietin? |
- is made in the kidneys and stimulates hemoglobin/RBC production when oxygen levels are low |
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What determines the binding of oxygen to hemoglobin? |
PO2 of environment and affinity for oxygen |
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what is loading? |
when hemoglobin binds to oxygen in the lungs |
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what is unloading? |
when oxyhemoglobin drops off oxygen in the tissues
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what does high and low PO2 favor...loading or unloading? |
low PO2, Hb GIVES UP (unloads) oxygen
HIGH PO2, Hb BINDS (loads) to oxygen |
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what does it mean if there is a shift to the LEFT for hemoglobin's dissociation curve? |
a shift to left would cause more affinity and less unloading of oxygen |
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what does it mean if there is a shift to the RIGHT for hemoglobin's dissociation curve? |
a shift to the RIGHT would cause lower affinity and more unloading of oxygen |
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what factors cause a shift to the RIGHT for hemoglobin? |
- increase in CO2 - increase in H+ (Bohr effect) - increase in 2,3-DPG - increase in temperature |
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WHAT IS 2,3-DPG? |
- shifts Hb curve to right - causes more oxygen to be released to tissues from hemoglobin |
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what is the bohr effect? |
it lowers the affinity of oxygen to bind so oxygen can be released to cells - more unloading occurs at lower ph (more H+) |
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what is the difference between fetal and adult hemoglobin? |
Fetal Hb = HIGHER affinity for oxygen than adult Hb so curve SHIFTS LEFT |
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What are the differences between hemoglobin and myoglobin? |
MYOGLOBIN: - stores oxygen - is a left shift (higher affinity to oxygen) - curve is hyperbolic - only 1 heme group and can only carry 1 O2 molecule - in skeletal and cardiac muscles
HEMOGLOBIN: - transports oxygen - curve shifts to RIGHT - curve is sigmoidal - has 4 heme groups, so 1 Hb molecule binds to 4 oxygen molecules - in RBCs
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How is CO2 transported in blood? |
is carried in the blood in 3 forms: - dissolved in plasma membrane - as carbaminohemoglobin attached to an amino acid in Hb - as bicarbonate ions (how most CO2 is carried) |
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what is the chloride shift? |
is a way to regulate CO2 starts with CO2 + H20 yields H2CO3 yields H+ + HCO3- WHEN CO2 DIFFUSES OUT OF CELL: - a lot of CO2 is in RBC, where there is the enzyme carbonic anhydrase, which binds CO2 with wather and yields carbonic acid - then carbonic acid turns into H+ + HCO3-, where HCO3- is moved out of the cell in exchange of Cl- ions that move in - this exchange causes the CO2 yield H+ + HCO3- reaction to continue
this reaction is important for picking u the rest of the CO2 in tissues and for making more bicarbonate for blood buffering |
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what is the reverse chloride shift? |
is getting rid of all that nasty CO2 - starting product starts with H+ +HCO3- and ends with CO2 and water - formation of co2 is favored - binding of oxygen to Hb decreases its affinity for H+, where H+ combines with HCO3- and more CO2 is formed |
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what is the major buffer in blood? |
bicarbonate ion |
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what is acidosis? |
when blood ph falls below 7.35 |
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what is respiratory acidosis? |
is hypoventilation- when not breathing enough and therefore CO2 not able to be removed from lungs; carbonic acid is high |
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what is metabolic acidosis? |
excessive production of acids, loss of bicarbonate |
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what is alkalosis? |
when blood ph rises above 7.45 |
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what is respiratory alkalosis? |
hyperventilation- rate of ventilation is faster than CO2 production. less carbonic acid forms, PO2 is low |
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what is metabolic alkalosis? |
inadequate production of acids or overproduction of bicarbonates, loss of digestive acids from vomiting |
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How is respiration involved in maintaining acid/base balance? |
ventilation can compensate for metabolic component - person with metabolic acidosis will hyperventilate - person with metabolic alkalosis will hypoventilate |
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Where is the main |
MEDULLA OBLONGATA |
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What are chemoreceptors? |
automatic control of breathing is influenced by feedback from chemoreceptors, which monitors ph of fluids in the brain and ph, PO2 and PCO2 of blood |
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Where are they located and how are they activated? Why CO2 and pH are the primary regulators of respiration? |
- central chemoreceptors located in medulla! - peripheral chemoreceptors in carotid and aorta arteries |
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what are the functions of the kidney? |
- maintain proper water balance in body - regulate concentration of ions such as Na+, K+, CA++, etc... - maintain plasna volume and regulate blood pressure - maintain proper acidic base balance of body - maintain osmolality of body fluids - removes wastes from body - secretes erthropoietin, renin
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what is a nephron? |
is the functional unit of the kidney - kidneys have ALOT of nephrons - consists of small tubles and associated blood vessles
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where is the entry point into a nephron? |
glomerulus |
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what are the four processes of the nephron? |
1. FILTRATION - filtrate flows from the glomerular capsule as blood flows through glomerular capillaroes 2. REABSORPTION - occurs when filtrate passes through the tubules - materials to be keps are reabsorbed across epithelial cells lining tubules and transported to pertibular capillaries 3. SECRETION - opportunities for body to get rid of non-filtered materials - selective transfer of non filtered materials from pertubular blood into tubular lumen for removal 4. EXCRETION - removal of all waste materials - moved to bladder and then voided |
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what is the composition of ultrafiltrate? |
contains everything EXCEPT formed elements and plasma proteins |
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How does ultrafiltrate differ from blood and plasma and why some components of blood do not appear in the ultrafiltrate and urine? |
- Differs from blood because blood contains formed elements and plasma and ultrafiltrate does not contain these elements
- some components of blood do not appear in the ultrafiltrate and urine because capillaries of the glomerulus are fenestrated---they have large pores that allow water and solutes to leave arterioles but not blood cells and plasma proteins |
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what is tubular reabsorption? |
- most of what enters kidneys and nephrons will leave and enter the blood - reabsorption = highly selective recycling efficiency: - 99% water - 100% sugars - 99.5% salts (Na, Ca, K, Cl) |
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for reabsorption, how much water is filtered per day and excreted as urine? |
180 L of water is filtered/day ad 1-2 L is excreted as urine
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where does most reabsorption occur? |
85% reabsorption is in proximal tubules and descending loop of henle |
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the proximal tubule and active transport |
- cells of proximal tubules are joined by tight junctions on the apical side, which contains microvilli and have lower Na+ concentration than the filtrate inside the tubule due to Na+/K+ pumps on the basal side of the cells - Na+ from filtrate diffuses into these cells and is then pumped out to the other side |
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proximal tubule and passive transport |
- pumping of sodium into the interstitial space attracts negative Cl- out of the filtrate - water then follows Na+ and Cl- into the tubular cells and the interstitial space - increased concentration of salts and water diffuses into peritubular capillaries |
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how much Na+. Cl- and water are reabsorbed in PCT and returned to the bloodstream |
about 65% |
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how much is reasborped in the descending loope of Henle? |
an additional 20% |
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how much of filtered water and salt are reabsorbed early in nephron transport |
85% |
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what is secondary active transport in the proximal tubule? |
glucose, amino acids and Ca++ are reabsorbed in proximal tubule by secondary active transport |
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what is the importance of the loop of Henle? |
is the reason why humans can excrete urine that is hypertonic to their blood - is a countercurrent multiplier system: descending and ascending limbs of loop of henle represent flow in opposite directions |
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characteristics of the descending tube of loop of henle |
only permeable to water |
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characteristivs of ascending tubules of loop of henle |
impermeable to water and only permeable to salts - active transport |
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what is the mechanism of the ascending loop of henle |
salt is actively pumped into the interstitial fluid - Na+ is moved into interstitial space via the sodium potassium pump - Cl- follows Na+ passicely due to electrical attraction and K+ passively diffuses back into filtrate |
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what occurs in the descending loop of henle? |
permeable to water , not salt - water is drawn out of the filtrate and into the interstitial space where it is quickly picked up by capillaries - as it descents, the fluid becomes more solute concentrated |
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what does the countercurrnet multiplier system accomlish? |
- the ability to recover water! - if there was no hypertonic interstitial fluid then there woul de no way to persuade water to leave the nephron and enter back into the circulatory system - this means that our urine would isotonic to our blood...we would need a lot of water to balance the water lost in our urine |
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role of aldosterone in Na/K Balance |
90% filtered Na+ and K+ reabsorbed before DCT - Remaining is variably reabsorbed in DCT and cortical CD according to bodily needs - aldosterine controils K secretion and Na reabsorption |
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sodium and potassium regulation |
aldosterone - important for secreting K and absorbing Na - is the only way K ends up in urine |
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renin-angiotensin aldosterone system |
is activated by the release of RENIN from GRANULAR CELLS within afferent arteriole - renin converts angiotensinogen to angiotensin I, which is converted into angio II by angiotensin converting enzyme in lungs - angio II stimulates release of aldosterone Na reabsorbed in SCT of nephrone |
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what is the macula densa |
inhibits renin secretion of Na is too high - causes less aldosterone secretion and more Na excretion |
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what is atrial natriuretic peptide? |
- is produced by atria due to stretching of walls occuts if blood is too high - acts opposit to aldosterone - promotes removal of Na so water can leave - stimulates salt and water excretion - acts as an endogenous diuretic |
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what are the order of events in the digestive tract |
1 MOTILITY - ingestion: taking food into mouth - mastication = chewing - deglutition = swallowing - peristalsis= one way movement through tract - segmentation= churning/mixing 2. SECRETION - exocrine= digestive enxymes - endocrine = hormones 3. DIGESTION - breaking food down into smaller units 4. ABSORPTION - passing broken down food into blood or lymph 5. STORAGE AND ELIMINATION 6. IMMUNE BARIER |
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what are the functions of the stomach? |
- stores food - churns food to mix with gstric secretions - begins protein digestion...does not hydrolyze proteins, but acid conditions cause loss of tertiary, secondary structures - kills bacteria in food (the acid) - secretes intrinsic factor - no typical food absorption in stomack, only alcohol and NSAIDs - moves food into small intestine in form of chyme |
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what are gastric pits? |
are at the base of folds that lead to gastic glands with secretory cells |
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what are goblet cells? |
secrete mucus to help protect stomach lining from acid |
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what type of cells secrete HCl and intrinsic factor--helps small intestine absorb vitamin B 12 |
PARIETAL CELLS
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What type of cells secrete pepsinogen? |
chief cells |
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what doe enterochromaffin like cells secrete |
histamine and seratonin |
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what do G cells secreteq |
gastrin |
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what do D cells secrete |
somatostatin |
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what is the function of gastrin? |
- are made in G cells and carried to parietal cells in blood - stimulates the SECRETION OF HCL from parietal cells - also stimulates ECL cells to make histamine |
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what are three functions of HCl |
- reduces ph to 2 - proteins are denatured (allows enzyme access) - pepsnogen is onverted to active pepsin - serves as the optima ph for pepsin activity |
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what are the functions of the small intestine? |
- complete digestion of carbohydrates, proteins and fats - absorption of nutrients - most digestion is done through use of pancreatic enzymes |
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what are brush border enzymes? |
help activate pancreatic enzymes - enterokinase (activates trypsin, which is active form), disaccharidaases, peptidases, phasphatases |
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what is the process of digestion and absorption for carbohydrates? |
- starch digestion begins in mouth with salivary amylase and continues in intestine with pancreatic amylase - brush border enzymes finish breaking down resulting products and other disaccharides - monosaccharides are absorbed across the epithelium into capillaries |
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what is the process of digestion and absoprtion for proteins? |
- begins in stomach with pepsin to produce short chain polypeptides - finishes in duodenum and jejunum with pancreatic trypsin, chymotrypsin and elastase and carboxypeptidase and the brush border enzyme aminopeptidase - free amino acids absorbed into capillaries |
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digestion and absoprtion of fats process |
- begins in duodenum when bile emulsifies the fat and lipase breaks it down into fatty acids - phospholipase A digests phospholipids into fatty acids - fatty acids and monoglycerides move into bile micelles and are transported to brush border - inside the epithelial cells, they are regnerated into triglycerides, cholesterol and phospholipids and combined with proteins to form chylomicrons - enter lacteals |
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what is the function of the large intestine? |
- absoprtion of water, electrolytes, vitmin K, and some B vitamins - production of vitamin k and b - STORAGE OF WASTE PRODUCTS - no digestion occurs here |
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what does pancreatic juice contain? |
contains water, bicarbonate, and digestive enzymes, which include amylase (starch), trypsin (proteins) and lipase(fats)
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how are pancratic enzymes activated in the small intestine? |
- most are inactive(zymogens) until reach small intesting - enterokinase activates trypsinogen into trypsin to digest protein - trypsin activates other enzymes |
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what are the main functions of the liver? |
1. DETOXIFICATION OF BLOOD - can remove hormones, drugs, and otehr substances in three ways: secreted into bile, phagocytized, and chemically altered 2. carbohydrate metabolism 3. lipid metabolism 4. protein synthesis 4. SECRETION OF BILE |
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what is the liver important for for teh secretion of glucose? |
- liver helps balance blood glucose levels by removing glucose and storing it as glycogen or by breaking down glycogen and releasing it into the blood - liver can also make glucose from amino acids and convert fatty acids into ketones |
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how are products of digestion absorbed in intestines delivered to the liver and how does blood leave? |
are delivered via HEPATIC PORTAL VEIN - leave via HEPATIC VEIN |
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what are liver lobules? |
are functional units formed by hepatic plates |
