Physiology mt 2
The detailed events in the cardiac cycle that generate blood flow. This includes a description of relationships between volumetric changes, pressure and blood flow in the chambers, the opening and closing of valves.
2 pumps = connected in series = blood coming back from systemic circulation (everything going out into body) Oxygen low blood is pumped into the right ventricle then right atrium to pulmonary system then left atrium to left ventricle into systemic circulation. Pumps blood from right to left in heart (connected in series) Blood flow: pressure changes Flows from higher pressure to lower pressure P1 - P2 = DP DP = pressure gradient (difference in pressures) Pressure difference and resistance determines flow Blood flow is adjusted to make sure it is meeting metabolic demands of tissues Highest pressure at heart (driving pressure), decreases over distance. Highest pressure in pulmonary system at base of pulmonary artery Decreases as it flows to smaller and smaller vessels Hydrostatic = pressure of a fluid (really hydraulic NOT PARTIAL) pressure in vessel Decreases 90% from aorta to vena cava (heart to exiting heart
How resistance in the arterioles may be modulated and how that modulation affects exchange in the capillaries.
3 controls of arteriole radius Neural controls sympathetic nervous system releases norepinephrine vasoconstriction Inc signal blood vessel constricts, resistance inc neurons release nitric oxide vasodilation Hormonal controls Local controls Organs and tissues alter their own arteriole resistance (local/intrinsic control) Self regulate blood flow Induces changes caused by autocrine/paracrine agents Active hyperemia Metabolic rate of tissue inc Slight reduction of O2, lactic acid builds up Arterials dilate in tissue organ Inc in flow Metabolism goes up, blood flow goes up Reactive hyperemia If something reduces blood flow to tissue over time (obstruction) Metabolites build up Remove obstruction Blood flow goes up then eventually goes back to normal Ex lean on something for a while and elbow gets red NO = nitric oxide (from vascular endothelial cells), vasodilator Autoregulation in organs even if there is changes in perfusion pressure (in brain) Can have a range of perfusion pressures But blood flow stays relatively constant despite decreasing or increasing pressure Also resistance determines flow If they have same length/diameter resistance is the same
Explain how a sphygmomanometer works.
A sphygmomanometer is a device that measures blood pressure. composes of an inflatable rubber cuff, which is wrapped around the arm. A measuring device indicates the cuff's pressure. A bulb inflates the cuff and a valve releases pressure. A stethoscope is used to listen to arterial blood flow sounds. As the heart beats, blood forced through the arteries cause a rise in pressure, called systolic pressure followed by a decrease in pressure as the heart's ventricles prepare for another beat. This low pressure is called the diastolic pressure. The sphygmomanometer cuff is inflated to well above expected systolic pressure. As the valve is opened, cuff pressure (slowly) decreases. When the cuff's pressure equals the arterial systolic pressure, blood begins to flow past the cuff, creating blood flow turbulence and audible sounds. Using a stethoscope, these sounds are heard and the cuff's pressure is recorded. The blood flow sounds will continue until the cuff's pressure falls below the arterial diastolic pressure. The pressure when the blood flow sounds stop indicates the diastolic pressure. Systolic and diastolic pressures are commonly stated as systolic 'over' diastolic. For example, 120 over 80. Blood flow sounds are called Korotkoff sounds.
Explain the connection between preload, contractility, afterload and stroke volume
Afterload = force heart pumps against to eject blood Preload - measure of stretch or filling pressure Stroke volume = volume of blood per beat Contractility = force or strength of contraction Inc preload = inc stroke volume Frank-Starling Law of the Heart Contractile force vs pressure made by the heart or volume of the heart vs output per stroke (both same) Cardiac muscle is like a rubber band, more tension as you pull the rubber band out As passive tension is increased (stimulate cardiac muscle), this is how much pressure is generated Diastolic phase = relaxation phase (ventricles relax and fill with blood) At the end of diastolate, the amount of blood in ventricles is the end diastolic volume In a nutshell: Starling's law of the heart = ventricular contractile strenght increases with greater ventricular filling due to increased venous return of blood. Stretching myosin and actin filaments to generate more force
Describe how electrical potentials are transmitted through myocardial cells. How are electrical potential transmitted through the heart (including the roles of the SA and AV nodes)?
All cardiac muscle cells are electrically linked to one another, by structures known as gap junctions (see below) which allow the action potential to pass from one cell to the next. This means that all atrial cells can contract together, and then all ventricular cells. Steps: An electrical stimulus is generated by the sinus node (also called the sinoatrial node, or SA node). This is a small mass of specialized tissue located in the right upper chamber (atria) of the heart. The sinus node generates an electrical stimulus regularly, 60 to 100 times per minute under normal conditions. The atria are then activated. The electrical stimulus travels down through the conduction pathways and causes the heart's ventricles to contract and pump out blood. The 2 upper chambers of the heart (atria) are stimulated first and contract for a short period of time before the 2 lower chambers of the heart (ventricles). The electrical impulse travels from the sinus node to the atrioventricular node (also called AV node). There, impulses are slowed down for a very short period, then they continue down the conduction pathway via the bundle of His into the ventricles. The bundle of His divides into right and left pathways, called bundle branches, to stimulate the right and left ventricles. Normally at rest, as the electrical impulse moves through the heart, the heart contracts about 60 to 100 times a minute, depending on a person's age. Each contraction of the ventricles represents one heartbeat. The atria contract a fraction of a second before the ventricles so their blood empties into the ventricles before the ventricles contract.
The physical principles that determine flow, flow rate, and pressure differences in each stage of circulation through the body.
Arterials are major sites of resistance to blood flow in circulation How does blood flow through this closed circuit (systemic circulation) Pulmonary works at lower pressure Blood flows down pressure gradient The absolute value of the pressure is not important , it's the difference in pressures (pressure gradient) How does flow differ between vessels Same flow rate bc same pressure gradient Also resistance determines flow If they have same length/diameter resistance is the same Resistance = tendency of the vascular system to oppose flow, Flow = 1/R Influenced by Length of tube L Radius of tube r Viscosity of blood n R = 8Ln/r^4 In a normal human length of system is fixed, blood viscosity and radius has the greatest effect on resistance. Larger radius = less resistance Double radius = reduce the resistance x16 If one tube has a radius of one and one tube has a radius of 3, what is the difference if all other factors are the same = 3^4 Flow = P1 - P2 / R Resistances connected in series = add resistances Rt = R1 + R2 + R3 .... Has higher total resistance Systemic circulation in series with pulmonary circulation Resistances in parallel 1/Rt = 1/R1 + 1/R2 + 1/R3 Vascular beds have parallel Blood flow through 4 parallel tubes is all equal (assuming they all have the same diameter, length, and therefore resistance) 1 L/min each = 4 L/min What goes in comes out If one is constricted: Others account for lost blood flow because they have less resistance = blood flow is unchanged Capillaries = where all exchanges are happening How is velocity influenced Velocity is related to the cross-sectional area For a given flow rate, narrow vessel = higher velocity Wide vessel = lower velocity Highest cross sectional area = capillary beds = lowest velocity Good because it allows time for exchange What determines mean arterial pressure: Blood volume Effectiveness of the heart as a pump (cardiac output) Resistance of the system to blood flow Relative distribution between arterial and venous blood vessels
How to define and artery and vein
Artery = Blood vessel carrying blood away from the heart Vein = Blood vessel carrying blood back to the heart
Describe how blood pressure is controlled by the cardiovascular and renal systems.
Autoregulation of blood flow - exists to maintain flow despite changes in pressure Ex. if blood pressure drops, flow and resistance will be autoregulated to maintain blood flow to tissues (local blood vessel diameters increase) Blood flow through body tissues = tissue perfusion. Involved in Delivery of oxygen and nutrients to and removal of wate from tissues Gas exchange in lungs Absorption of nutrients from digestive tract Urine formation in kidneys Velocity of blood flow is inversely related to cross sectional area High cross sectional area = low velocity. This is true in capillaries so oxygen and nutrients can be absorbed. Autoregulation = local factors change blood flow in capillary beds in response to chemical changes. Intrinsic control mechanisms that control blood flow to local tissues. Metabolic (chemical) Exercise - metabolic activity of organ increases, O2 decreases, increase in metabolic waste in organ interstitial fluid (CO2, lactic acid) In response to low O2 or high CO2, tissue releases vasodilator nitric oxide Arterials and pre capillary sphincter dilates Blood flow to organ goes up O2 goes up This overrides sympathetic nervous system desire for vasoconstriction If SNS tries to vasoconstrict skeletal muscles during exercise, demand for O2 overrides this Nitric oxide can also be released from endothelial cells due to ACh, histamine, or stress Myogenic mechanism Maintains constancy of blood flow in response to small changes in blood pressure Vascular smooth muscle contracts with stretch or relaxes with reduction in stretch Ex. there is a decrease in pressure, decrease in blood flow, less stretch on vessel wall in organ, arteriolar dilation in organ, restoration of blood normal blood flow in organ If this wasn't here, a reduction in blood pressure would mean a reduction in blood flow Also in the opposite direction - laying down from standing up. Stretch blood vessel wall = vasoconstriction so blood vessels don't swell up, leading to edema. Arterioles are important in affecting total peripheral resistance and controlling blood pressure in body Do not all respond together though Can control flow locally Divert blood to where you need it Take away blood from where you don't need it (ex exercise = more blood to legs less blood in gut) To maintain total peripheral resistance, if blood vessel to muscles dilates, then blood vessel to ex. gut must constrict To balance local need for more blood in organs with global need to maintain MAP MAP = CO x TPR If in exercise, metabolism vasodilation happens too much so that MAP decreases, SNS will step in and constrict to avoid that
Explain the major mechanisms of capillary exchange, filtration and absorption (i.e. Starling's Hypothesis).
Blood flows from arteries, to arterioles, to meta-arterioles, to capillaries. (oxygenated) Then to venules then veins (deoxygenated) Pre capillary sphincters control blood flow through capillaries. Capillaries do not have smooth muscle like arterioles. But they have endothelial cells lining Capillary is surrounded by interstitial fluid 4 forces determine if fluid is pushed from interstitial to capillary or from capillary to interstitial: Starling forces 2 hydrostatic pressures created by fluid Pressure from fluid in capillary (Pc) Pressure forcing fluid to move into interstitial causing filtration Controlled by arterial and venous pressures and resistance Inc in pressure inc Pc Pressure from fluid in interstitial (Pi) Pushes fluid back into capillary membrane Pi is low bc fluid is trapped in gel-like interstitium created by collagen 2 colloid osmotic pressure/oncotic pressure (pressure created by proteins) Capillary (πc) From plasma proteins, osmosis Pulls fluids from interstitium to capillary Interstitial (πi) From proteins in interstitium Pulls fluid out of capillary (but capillary has small pores so not much can come out) These pressures give net filtration pressure: If positive, there is net filtration from capillary to intersitium If negative, direction of flow is towards capillary (reabsorption) Also Kf, filtration coefficient is a factor = pore size/# of capillaries = permeability of capillary membrane Rate of filtration = Pc of arterial end (oxygenated) is higher than Pc of venous end (deoxygenated) Net filtration at arterial end and net reabsorption at venous end Slightly higher filtration, excess filtrate is returned to circulation through lymphatic vessels Factors that increase filtration in capillaries: Lymphatic damage = edema
5. Describe the physiology of the different regions of the nephron.
Bowman's capsule containing a network of capillaries = glomerulus Glomerulus connected to afferent and efferent arterioles Blood is filtered in glomerulus and ions/solutes go into renal tubule There are blood capillaries that run along renal tubule Filtrate then goes through PCT, loop of henle, DCT, then leaves through collecting duct (blood reabsorbs what is needed, and gets rid of waste--determines composition of urine)
16. Explain a countercurrent multiplier and a concurrent exchanger.
COUNTERCURRENT EXCHANGE Generates concentration gradient within medulla of kidney Through selective permeability of sodium and water, generate concentrating mechanism Requires a lot of energy to set up concentration gradient Loop of Henle = differential permeability influencing capacity to concentrate medulla Bowmans filtering -> taken up in PCT -> H2O and Na+ loop of henle (if sodium goes chloride is going to follow) Lower water content = higher concentration of osmotic particles Most is passive except for in thick ascending limb there is a lot of active START: want to increase concentration into loop of henle (greater than 300 milliosmoles) Thick ascending limb: not permeable to water, pumps out a lot of Na+ (NaCl) Puts osmotically active particles in interstitium Descending limb Very permeable to water, lots of water leaves Higher in sodium concentration At loop of henle more and more sodium pumped out Concentrating inner portion of medulla = adding more and more sodium but not diluting it with water Back at top even more sodium is pumped out (CHANGING THIS GRADIENT ALTERS HOW MUCH WATER YOU LOSE OR REABSORB) COUNTERCURRENT MULTIPLIER/CONCURRENT EXCHANGE (SAME THING) In loop of henle, develops a concentration of 1200 mOsm/L in medulla of kidney Descending limb - permeable to water, water leaves bc there is osmotic pressure bc sodium in medulla from ascending limb is dragging water out, making filtrate more concentrated. Water leaves until conc outside of descending limb = conc of medulla Ascending limb - pumping sodium out into medulla, making filtrate less concentrated. Loop of henle is not permeable to water so water cannot follow Na+ and leave into medulla. Conc inside lower than conc inside. High concentration stuff goes in and down and high concentration stuff goes up and out, this increases concentration along loop of henle Filtrate goes from concentrated to less concentrated, now since there's new sodium to pump out it leaves at ascending which further concentrates the medulla. Then because there's more sodium in medulla, even more water comes out which further concentrates filtrate in descending = Eventually medulla becomes very concentrated Multiplies and multiplies = countercurrent multiplication Countercurrent multiplier = two fluids flowing in opposite direction and they have different concentrations--this concentration gradient drives exchange of ions Concurrent exchanger = two fluids moving in the same direction and have similar concentrations, so there is no potential for exchange
Define cardiac output and explain how heart rate and stroke volume effect it
Cardiac output = amt of blood ejected per unit time Cardiac output is the product of heart rate (HR) and stroke volume (SV) and is measured in liters per minute. HR is most commonly defined as the number of times the heart beats in one minute. SV is the volume of blood ejected during ventricular contraction or for each stroke of the heart.
What's the difference between stroke volume and cardiac output? How are they calculated?
Cardiac output is the product of heart rate (HR) and stroke volume (SV) and is measured in liters per minute. HR is most commonly defined as the number of times the heart beats in one minute. SV is the volume of blood ejected during ventricular contraction or for each stroke of the heart.
Explain the differences between mean arterial, systolic, and diastolic pressures.
Diastolic (DP) = minimum pressure Systolic (SP) = peak pressure Mean pressure more important - drives the blood through the different circulations Pulse pressure (PP) = SP - DP Mean arteriole pressure = MAP = DP + ⅓(PP) Heart has to maintain adequate perfusion pressure to overcome resistance (R) in various circulations - must always be enough of a pressure head to drive blood through system Mean arterial blood pressure = CO (cardiac output) x TPR (total peripheral resistance) MAP = SP + 2DP / 3
Summarize factors affecting stroke volume, heart rate and cardiac output
Diastolic (DP) = minimum pressure Systolic (SP) = peak pressure Mean pressure more important - drives the blood through the different circulations Pulse pressure (PP) = SP - DP Mean arteriole pressure = MAP = DP + ⅓(PP) Heart has to maintain adequate perfusion pressure to overcome resistance (R) in various circulations - must always be enough of a pressure head to drive blood through system Mean arterial blood pressure = CO (cardiac output) x TPR (total peripheral resistance) MAP = SP + 2DP / 3 Factors influencing heart rate Both subdivisions of autonomic nervous system Sympathetic inc Parasympathetic dec Plasma epinephrine, adrenaline (inc) Cardiac output = stroke volume x heart rate Distribution of blood to body organs System changes blood flow to organs, changes diameter of arterials/sphincters that go to these systems. Constrict = increases resistance to flow, heart has to change pressure to ensure adequate flow
What are the differences between cardiac and skeletal muscle (including length- tension characteristics and the generation of force and membrane potentials over time)? How do these features aid the functioning of the heart?
Difference between cardiac muscle tissue and skeletal muscle tissue = cardiac has branching structure and one nucleus
Describe the effect of exercise on cardiac output
Exercise = vasoconstriction of veins, reduces volume on venous side and makes it available for arterial side. Exercise = increased cardiac output
Describe factors affecting heart rate and force of contraction
Factors affect cardiac output by changing heart rate and stroke volume. Primary factors include blood volume reflexes, autonomic innervation, and hormones. Secondary factors include extracellular fluid ion concentration, body temperature, emotions, sex, and age. Inc force of contraction: An increase in preload results in an increased force of contraction by Starling's law of the heart; this does not require a change in contractility. An increase in afterload will increase contractility (through the Anrep effect). An increase in heart rate will increase contractility (through the Bowditch effect).
The figure below is a Pressure-Volume of the left ventricle. .Label all the events in the cardiac cycle as it relates to this loop.
Full cardiac cycle = a full cycle of relaxation (diastole) and contraction (systole) Diastole = relaxation -> ventricles filling with blood Systole = contraction -> atria and ventricles contract, push blood out Atria contracts a split second before ventricles = atrial kick. Ventricles contract and force blood out of the pulmonary artery and aorta to go to lungs and body. Pressure shoots up because ventricles contract, forcing blood out, forcing blood out and pressure goes down. As ventricles relax they fill back up with blood. Atrial kick forces last bit of volume out, if there are problems with atrial kick (ex atrial fibrillation) they cannot have full cardiac output.
Describe the effects of gravity on blood pressure—how is it different from the pressure induced by the contraction of the heart?
Gravity influences distribution of blood volume Stand up = Veins distend and more volume is in venous area, blood pressure momentarily decreases
Identify cardiovascular centers and cardiac reflexes that regulate heart function
Heart rate is controlled by the two branches of the autonomic (involuntary) nervous system. The sympathetic nervous system (SNS) and the parasympathetic nervous system (PNS). The sympathetic nervous system (SNS) releases the hormones (catecholamines - epinephrine and norepinephrine) to accelerate the heart rate. There are at least three neural mechanisms participating in this cardiovascular regulation: (1) the exercise pressor reflex, (2) the central command, and (3) the arterial baroreflex. The medulla contains the major nuclei that control blood pressure and the cardiovascular system.
Why blood flow is so slow in the capillaries and how flow rate affects exchange.
Highest cross sectional area = capillary beds = lowest velocity Good because it allows time for exchange
How do pressure, viscosity, and the shape of a vessel influence flow and flow velocity?
How does flow differ between vessels Same flow rate bc same pressure gradient Also resistance determines flow If they have same length/diameter resistance is the same Resistance = tendency of the vascular system to oppose flow, Flow = 1/R Influenced by Length of tube L Radius of tube r Viscosity of blood n R = 8Ln/r^4 In a normal human length of system is fixed, blood viscosity and radius has the greatest effect on resistance. Larger radius = less resistance Double radius = reduce the resistance x16 If one tube has a radius of one and one tube has a radius of 3, what is the difference if all other factors are the same = 3^4 Flow = P1 - P2 / R
How action potentials are generated and propagate through the different regions of the heart. Explain how this pattern contributes to blood flow through the heart chambers.
How wave of action potential moves across heart: SA node depolarizes and moves into right and left atrium Then to AV node where it is slightly delayed (can't pass down directly into ventricles because they are electrically insulated From slide: APs spread through myocardial cells through gap junctions. Impulses cannot spread to ventricles directly because of fibrous tissue. Conduction pathway: SA node. AV node. Bundle of His. Purkinje fibers. Stimulation of Purkinje fibers causes both ventricles to contract simultaneously.
19. The effect of ACE inhibitors on the production of ANG II, aldosterone release, Na+ reabsorption, ECF volume.
Inhibition of the angiotensin converting enzyme (ACE) is associated with a decrease in renal vascular resistance, an increase in renal blood flow and a redistribution of intrarenal blood flow toward juxtamedullary nephrons. If ACE is inhibited, it cannot convert angiotensin I into angiotensin II, does not have angiotensin II as a powerful vasoconstrictor so the renal vascular resistance will decrease and there will be increased blood flow. Used to treat hypertension? Angiotensin II constricts both the afferent (preglomerular) and efferent (post glomerular) arterioles but preferentially increases efferent resistance. At least three factors may contribute to this response
What are the functions of the lymphatic system?
It maintains fluid levels in our body tissues by removing all fluids that leak out of our blood vessels. Lymphatic System: Lymphatic vessels transport interstitial fluid. • Lymph nodes cleanse lymph prior to return in venous blood Collect liquid that has been leaking over time (capillaries) and return it to circulation lymphatic system, part of your immune system, has many functions. They include protecting your body from illness-causing invaders, maintaining body fluid levels, absorbing digestive tract fats and removing cellular waste.
13. How Na+ and K+, urea and water are moved throughout the nephron.
K+ HANDLING Low concentration in blood, higher concentration inside cells Small changes in K+ concentration can have disastrous effects on mV electrical potential in cells 4 to 5.5 mmol change in K+ causes fibrillation and death Decrease to 3.5 = arrhythmias and death K+ reabsorption: along the proximal tubule is largely passive and follows the movement of Na+and fluid (in collecting tubules, may also rely active transport). K+ secretion: occurs in cortical collecting tubule (principal cells), and relies upon active transport of K+across basolateral membrane and passive exit across apical membrane into tubular fluid UREA RECYCLING To get rid of ammonia when we break down proteins Filtered, 50% reabsorbed in PCT (lose some but take most back up) End up pumping out some urea Helps concentrate inner medulla as well Kidney failure = blood urea nitrogen increases.
15. Describe the role of the kidneys in regulating blood volume, sodium balance and blood pressure.
Kidneys control blood volume and blood pressure by removing more or less water. Water excretion is regulated by hormones Vasopressin - antidiretic = released in response to low blood volume or high plasma osmolality. Causes kidneys to retain more water by increasing water permeability of the collecting duct. Aldosterone - secreted by the adrenal cortex in response to low blood sodium, acts on collecting duct and distal tubule to reabsorb Na+ back into blood. Creates sodium retention = inc retention of water Renin - responds to low blood pressure. Produces angiotensin II, which causes vasoconstriction, the release of vasopressin and aldosterone, and thirst (to inc water intake) Atrial natriuretic peptide = released by atrial myocardium, responds to high blood pressure. To decrease blood pressure, it causes vasodilation, increases glomerular filtration rate (removing more fluid in urine, inhibits secretion of renin and aldosterone, inhibits sodium reabsorption by the collecting duct (bc if sodium is taken in water is taken in) Water and salts regulated by nephron DCT, made of simple cuboidal cells, is the place where initial adjustments are made to the filtrate aldosterone -> Na+ and Cl- is reabsorbed into blood, K+ and H+ are secreted into tubule. Almost all HCO3- is reabsorbed DCT normally impermeable to water but small amounts of H2O reabsorbed Collecting duct NaCl and Urea reabsorbed (but urea can be re enter into loop of henle -- urea recycling) Levels of water in collecting duct are regulated by ADH, allowing aquaporins into epithelium of collecting duct, water is reabsorbed. However, over hydrated = less ADH. Medulla is salty, so if water is given the opportunity to leave it will
Describe why blood pressure varies in different vessels of the systemic circulation.
Left ventricle wall is much thicker than the right ventricle wall because it has to pump against larger pressures.
What is the purpose of the lymphatic system?
Lymphatic System: Lymphatic vessels transport interstitial fluid. • Lymph nodes cleanse lymph prior to return in venous blood Collect liquid that has been leaking over time (capillaries) and return it to circulation
8. How the kidney can help with acute blood loss (hemorrhage).
Massive blood loss = dec in MAP, renin angiotensin system is stimulated. Angiotensin II is such a powerful vasoconstrictor in combination with sympathetic response that it can shut off GFR. Cells of kidneys lose nutrients, GFR sometimes can not function properly afterwards Autonomic regulation sympathetic nervous system Stimulates vasoconstriction of afferent arterioles. Preserves blood volume to muscles and heart. Cardiovascular shock: Decreases glomerular capillary hydrostatic pressure. Decreases urine output (UO) Start Exercising for a week, blood volume increases over time, can deliver more O2 to tissues (have not modified heart though)
10. How the kidney balances ion levels in the body.
Na+/Water regulate blood pressure HCO3-/H+ regulate acid base (pH of blood) What is reabsorbed into blood (red arrows) What is secreted into kidney (brown arrows) Ions leaving/entering ascending loop of henle and PCT proximal convoluted tubule
2. The functions and anatomy of the renal system.
Nephron consists of: Functional unit of the kidney. Consists of: •Blood vessels: Vasa recta. Peritubular capillaries. •Urinary tubules: Proximal convoluted tubule (PCT) Loop of Henle (LH). Distal convoluted tubule (DCT). Collecting duct (CD).
Describe the roles played by the following in circulation: Mitral valve, tricuspid valve, arteries, arterioles, capillaries, venules, and veins.
Path of DEOXYGENATED BLOOD 1.(deoxygenated) arrives in right atrium If it is from above diaphragm, enters through superior vena cava If it is from below diaphragm, enters through inferior vena cava From heart muscle, blood enters through coronary sinus 2.blood then travels through tricuspid valve into right ventricle 3. Then travels through pulmonary valve into pulmonary artery 4. Blood travels through pulmonary artery to lungs where oxygen will be taken up and CO2 will be dropped off Path of OXYGENATED BLOOD Returns to heart via 1 of four pulmonary veins Then enters the left atrium Travels through mitral valve into left ventricle Blood exits heart through aortic valve Then travels via aorta to rest of body Right side of heart contains deoxygenated blood Left side of heart contains oxygenated blood Blood flows from arteries, to arterioles, to meta-arterioles, to capillaries. (oxygenated) Then to venules then veins (deoxygenated)
Distinguish between positive and negative inotropic factors
Positively inotropic agents increase the strength of muscular contraction. The term inotropic state is most commonly used in reference to various drugs that affect the strength of contraction of heart muscle (myocardial contractility). Negative inotropes weaken the heart's contractions and slow the heart rate. These medicines are used to treat high blood pressure (hypertension), chronic heart failure, abnormal heart rhythms (arrhythmias), and chest pain (angina). negative ionotropy = decreased contractility ( Positive ionotropy = increased contractility (epinephrine and norepinephrine / stimulation of SNS) Exercise = inc in sympathetic outflow, inc in epinephrine, inc contractility
How does resistance in the pulmonary circulation compare with resistance in the systemic circulation? How does pressure in the pulmonary circulation compare with pressure in the systemic circulation?
Pulmonary works at lower pressure
4. Understand filtration and the factors that affect filtration rate.
Rate depends on: Hydrostatic pressures Colloid osmotic pressure Hydraulic permeability +10 mmHg pressure, high permeability Bowman's capsule is around it Driving forces of reabsorption and filtration Filtered into glomerular capsule Afferent and efferent arterials control glomerular filtration (volume being filtered) Efferent = blood leaving Afferent blood entering Arterials can be dilated or constricted (inc or dec glomarular filtration) Capillary bed (very leaky in glomular network) 4 forces involved in filtration (Starling's) Capillary pressure Interstitial fluid pressure Intersitital fluid colloid osmotic pressure Plasma colloid osmotic pressure Very effective in filtering fluid into bowman's capsule Pfluid is pressure of fluid in bowman's capsule, pushes fluid back into capillary bed Bowman's capillary network is not permeable to proteins PH - pi - Pfluid = net filtration pressure PH (hydrostatic pressure) is altered most Glomerular filtration Enters capsule space Water Small proteins Sugars Amino acids Vitamins Ions Washes (urea) LEaves capsule space Water (~80%) Red blood cells White blood cells Platelets Large proteins GFR = ~120-125 mL per minute (~60-65 mL for each kidney) Influenced by altering resistance in efferent and afferent arteries
7. Describe reabsorption (active and passive) and secretion including what, where and controls.
Reabsorption is the movement of substances out of tubule, into interstitial space and into capillaries. Secretion - substances move through blood into interstitial space into tubules. First filtrate travels to PCT Reabsorbed: PCT has simple cuboidal cells w mitochondria and microvilli 65% Na+ ions reabsorbed here w/ Cl- 65% water leaves by osmosis 65% K+ reabsorbed 90% HCO3- reabsorbed, important in maintaining pH 100% Glucose and amino acids reabsorbed back into blood 50% urea reabsorbed Secreted: Ammonia and drugs secreted into tubule Loop of henle: NaCl leaves passively from thin ascending limb but is actively pumped from thick ascending limb 25% NaCl reabsorbed from loop of henle
3. Explain renal blood flow control.
Renal blood vessels: •Afferent arteriole: Delivers blood into the glomeruli. •Glomeruli: Capillary network that produces filtrate that enters the urinary tubules. •Efferent arteriole: Delivers blood from glomeruli to peritubular capillaries •Peritubular capillaries: Deliver blood to vasa recta. vasa recta are the blood capillaries that surround the loop of Henle in the juxtamedullary nephrons. But, peritubular capillaries are the blood capillaries that surround the PCT and DCT of the cortical nephrons. Amount filtered - amount reabsorbed + amount secreted = amount secreted in urine?
18. Describe the regulation of pH in the blood including the role of the lungs and the kidney.
Take in too much water Water content of blood is high Lowers osmolarity In the brain (hypothalamus) there are osmoreceptors Become stimulated, produces less ADH This lowers the level of water reabsorbed by kidney Urine output high Return to normal water content Too much salt/sweating lose too much water Water content of water becomes low, conc of solute inc Raises osmolarity Brain produces more ADH reabsorb more water from urine Urine output low Renin-angiotensin system Angiotensin More water absorption Vasoconstriction Tubular reabsorption of Na+, Cl- Inc sympathetic activity Lungs and kidneys maintain extracellular pH (conc. Of H+ ions), maintained in fairly narrow limit High H+ conc, low pH. Low H+ conc, high pH. 7.35-7.45 blood pH Why is it essential to regulate pH All enzymes are influenced by pH (most work best at ~7.4) - to maintain normal/optimal enzyme activities Normal metabolism Normal coordination Normal health Henderson Hasselbalch equation pH = pKa + log (concentration of conj. Base / concentration of weak acid) pH = 6.1 + log10 ( HCO3- / 0.03 x PCO2) Bicarbonate (conj base) / solubility of PCO2 in blood (weak acid) Kidneys control metabolic component (bicarbonate) Lungs control respiratory component (CO2) pH = 6.1 + log10 (kidneys/lungs) Kidneys filter bicarbonate and H+ H+ can come from other places such as from lactic acid, has other sources H+ from blood to urine Bicarbonate from urine to blood In PCT The bicarbonate at start is not necessarily reabsorbed. One bicarbonate in peritubular lumen - CO2 and water, which makes the bicarbonate that is reabsorbed. Amino acids in PCT cells produce ammonia, diffuse into filtered fluid and trap hydrogen ions. NH4 is eliminated in urine, and gets rid of excess H+ ions. There are also buffers that are filtered that trap H+ ions so they can be eliminated. (H2PO4-) How H+ disturbances are dealt with: Blood buffer system Respiratory mechanism (rapid) Alter level of ventilation alter CO2 level Renal mechanism (slow) Reabsorbed filter bicarbonate, add or take away bicarbonate pH is a result of balance between pCO2 and bicarbonate Metabolic = change in bicarbonate, respiratory = change in CO2 Kidney: proximal tubules reabsorb bicarbonate in the process aided by carbonic anhydrase Distal tubule: kidney adds or subtracts more bicarbonate (uses glutamine from liver). Generate new bicarbonate and excrete hydrogen. Can generate new bicarbonate and excrete hydrogen ions metabolic acidosis Caused by dec in HCO3- in blood, lowers pH under 7.35 Dec pCO2 to return pH to normal (respiratory compensation) Respiratory acidosis Failure of respiratory system to maintain PCO2, inc in PCO2 Lowers pH under 7.35 To bring back to normal kidneys produce more bicarbonate Metabolic alkalosis Inc in conc. Of bicarbonate Blood pH greater than 7.45 Two main causes Loss of H+ Or gain of HCO3- To compensate - inc PCO2 Respiratory alkalosis Failure of respiratory system (reduction of PCO2) that raises pH above 7.45 Ex abnormal hyperventilation To compensate - dec bicarbonate Ratio of HCO3- / PCO2 dictates this
How the baroreceptor reflex regulates blood pressure.
The Baroreceptor Reflex, which is fast-acting (within seconds) and acts via changes in Cardiac Output (stroke volume x heart rate) Total Peripheral Resistance (a measure of arteriolar constriction): like a faucet that regulates pressure from a hose.
How is heart beating generated and modulated?
The impulse starts in a small bundle of specialized cells located in the right atrium, called the SA node. The electrical activity spreads through the walls of the atria and causes them to contract. This forces blood into the ventricles. The SA node sets the rate and rhythm of your heartbeat.
How does the pressure generated in the Right Ventricle compare with pressure generated in the Left Ventricle? What are the major blood vessels exiting the ventricles and entering the atria?
The left ventricle of your heart is larger and thicker than the right ventricle. This is because it has to pump the blood further around the body, and against higher pressure, compared with the right ventricle. Large red vessel (the aorta) - Large artery that carries blood from the left ventricle to the arteries of the body. Large blue vessel (vena cava) _(includes the superior and inferior vena cava) - _Large vein that empties blood into the right atrium of the heart.
17. Explain the purpose and mechanics of the ionic gradient in the renal medulla.
This process allows for the recovery of large amounts of water from the filtrate back into the blood, which produces a more concentrated urine. The loop of Henle is responsible for ESTABLISHING the gradient and the vasa recta MAINTAINS the gradient. Establishes a vertical osmotic gradient counter current multiplication (CCM) in the loop of Henle which generates the gradient and counter current exchange (CCE) in the vasa recta which maintains the gradient work in concert to form the gradient. The vasa recta, the capillary networks that supply blood to the medulla, are highly permeable to solute and water -The vasa recta MAINTAINS the medullary vertical osmotic gradient. -Movement of solutes and water is PASSIVE in both the descending and ascending limbs of the vasa recta. 1.) Blood entering the descending vasa recta (in the cortex) is iso-osmotic. -As the vasa recta descends into the more concentrated medulla, solutes diffuse passively into and water diffuses passively out of the blood. 2.) The opposite occurs in the ascending vasa recta. -Water pulled out of the loop of Henle and collecting duct moves into the hypertonic interstitium and then into the ascending vasa recta -Solutes diffuse out of the ascending capillaries of the vasa recta and into the interstitium and the descending limbs of the vasa recta and move deeper into the medulla. -Water moves from the descending vessels to the ascending vessels. -This unique pattern results in the establishment of a countercurrent exchange. -Solutes recirculate in the medulla. -Water effectively bypasses the DEEPER REGIONS of medulla. -Water movement from renal tubules to interstitium to the vasa recta is favored because the flow rate of the vasa recta is MORE than twice that of the nephrons. This process concentrates urine and allows for large amounts of water/sodium to be recovered from the filtrate
What are the major functions of the cardiovascular system?
Transportation Respiratory Transport O2 and CO2 Nutritive Carry absorbed digestion products to liver and to tissues Excretory Carry metabolic waste products Regulation (maintains homeostasis) Hormonal Carry hormones to target tissues Temperature Divert blood to cool or warm the body Protection Blood clotting Immune Leukocytes, cytokines, and complement act against pathogens
12. The activity of the hormones that the kidneys produce.
Vasopressin - antidiuretic = released in response to low blood volume or high plasma osmolality. Causes kidneys to retain more water by increasing water permeability of the collecting duct. Aldosterone - secreted by the adrenal cortex in response to low blood sodium, acts on collecting duct and distal tubule to reabsorb Na+ back into blood. Creates sodium retention = inc retention of water Renin - responds to low blood pressure. Produces angiotensin II, which causes vasoconstriction, the release of vasopressin and aldosterone, and thirst (to inc water intake) Atrial natriuretic peptide = released by atrial myocardium, responds to high blood pressure. To decrease blood pressure, it causes vasodilation, increases glomerular filtration rate (removing more fluid in urine, inhibits secretion of renin and aldosterone, inhibits sodium reabsorption by the collecting duct (bc if sodium is taken in water is taken in) Control DCT (distal collecting tubule) with hormones Diuretics increase permeability of water in DCT Hormonal control of water reabsorption IN DCT ADH: increases water permeability of DCT and collecting duct Aldosterone: increases reabsorption of Na+from DCT and collecting duct ANP: inhibits Na+reabsorption from DCT and collecting duct Dump more sodium more water will leave ADH - changes permeability of collecting duct ADH causes expression of more channels for water (aquaporins) Water does not just freely move through walls GFR Hormonal regulation Juxtaglomerular cells release renin (raising blood pressure everywhere—how?), atria release ANP (atrial natriuretic hormone) (dilates afferent arterioles and so raises GHP) ANP produced in right atrium of heart (if atrium is over filling) Ex reduction in arterial blood pressure Lower GFP, macula densa releases renin Renin interacts with protein called angiotensinogen Converted by renin to angiotensin I (in plasma) Angiotensin I enters pulmonary circulation ACE (angiotensin converting enzyme) converts angiotensin I into angiotensin II Constricts systemic arterioles, raises arterial blood pressure Raises GFR Also stimulates adrenal cortex Causes the release of aldosterone, causes inc in sodium reabsorption by kidney Inc vascular volume and inc arterial blood pressure Wherever sodium goes, water follows. Regulate sodium = regulate water.
1. The concept of a countercurrent multiplier.
countercurrent multiplier system: An active process occurring in the loops of Henle in the kidney, which is responsible for the production of concentrated urine in the collecting ducts of the nephrons. (explained later)
9. How the kidney regulates extracellular fluid volume and osmolarity.
regulate the volume and osmolality of the extracellular fluid by altering the amount of sodium and water excreted. This is accomplished primarily through alterations in sodium and water reabsorption, the mechanisms of which differ within each nephron segment.
