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ZOOL 401 Exam 4
Terms in this set (61)
Cardiac output (CO)
Vessels determine what portion of ______ reaches various tissue beds in body. Vessels include: ______, ______, ______, ______.
*The higher the compliance of a structure, the more easily it can be stretched (compliance = volume/pressure)
The walls of arteries consist of ______ muscle and ______ tissue. Arteries are ______ compliant than veins. Compliance refers to the ability of a structure to be ______. Low compliance of arteries allows them to provide ______.
Arteries are capable of ______: During systole, the aorta and arteries ______ to accommodate the ejected blood. During diastole, the aorta and arteries relax or ______, which forces blood through downstream vessels.
Movement of blood
Pressure gradients drive ______ throughout heart. Pressure gradients also impact ______ through blood vessels.
Blood flow is determined by: ______ in aorta/vena cava and ______. Arteries are under ______ pressure; they deliver blood to organs (______). Veins are ______ pressure system; they hold blood (______).
Blood flow (F) is determined by: F = (P1-P2)/R. P1 = pressure in ______, P2 = pressure in ______, R = ______. P2 is very ______ compared to P1 and is considered to be ______. Pressure in aorta is ______ to pressure measured in any major systemic artery. This implies that resistance through the major arteries is quite ______.
Systemic arterial pressure starts out ______ higher than pulmonary artery pressure; returns to similar values by the time the blood reaches the ______. So, resistance to blood flow is about ______ greater in systemic circulation than in pulmonary circulation. Most overall resistance in systemic circulation occurs in the ______.
Note that ______ is the same in the left and right ventricles. The resistance in the lungs is relatively ______ compared to the systemic circulation, so the right ventricle ______ have to generate as much force to open the semilunar valve.
Stroke volume (increase SV, increase pulse pressure)
Speed of ejection of the SV (increase rate, increase pulse pressure)
Arterial compliance (increase compliance, decrease pulse pressure)
Arteriosclerosis (stiffening of the arteries)
______ is the peak arterial pressure; occurs during contraction of ventricle. When blood leaves arteries, pressure decreases to a minimum called ______. Difference between systolic and diastole pressure = ______. It can be felt as a pulsation or throb in the arteries of the wrist or neck with each heartbeat. Magnitude of the pulse pressure depends on: 1) ______ 2) ______ 3) ______. Decreased arterial compliance occurs in ______.
*Known as korotkoff sounds
Inflate cuff until pressure ______ underlying artery and ______ blood flow. Gradually release pressure in cuff. When cuff pressure ______ peak systolic pressure, get momentary, high-velocity spurt of blood that is heard through stethoscope. Sound first heard = ______. When cuff pressure ______ diastolic pressure, vessel remains open and flow is again continuous. Point at which sounds disappear = ______.
Mean arterial pressure (MAP)
*MAP > 60 mm Hg is required to perfuse organs
______ is based on geometric mean of peaks and valleys that occur in artery due to fluctuating pressures. This equals 1/3 pulse pressure + diastolic pressure. We have homeostatic mechanisms that sense and maintain ______. The body ______ regulate pulsatile pressure itself (systolic and diastolic pressures ______ regulated; just the geometric mean of these two pressures).
Arteries reach tissues and divide into ______. The decrease in diameter results in ______ resistance and ______ in pressure. For this reason, arterioles provide most of the ______ in the systemic circulation.
Total peripheral resistance (TPR)
*CO = MAP/TPR
The overall resistance from the aorta, through systemic circulation, and back to heart = ______.
When an arteriole decreases its diameter, it ______ the downstream flow. This is because arterioles alter the distribution of blood in capillaries arranged in ______. In order for blood flow through one capillary bed (or tissue) to increase, blood flow through other beds/tissues must ______.
Arteriole resistance alters distribution of blood flow among capillaries arranged in ______. Total flow in arteries, arterioles, capillaries, and veins must all remain equal because they are arranged in ______ within a closed system.
*Arterial pressure increases -> arteriole walls and smooth muscle stretch (vasodilation) -> arteriole smooth muscle contracts (vasoconstriction)
In general, blood flow to organs remains ______ despite changes in blood pressure. The ability of vascular beds to maintain a constant flow is called ______. This occurs through ______ mechanisms and one of the mechanisms is the ______. This mechanism, also called the ______, occurs when stretch receptors are activated, depolarization occurs, and then calcium enters and stimulates smooth muscle contraction. Myogenic response: When perfusion pressure increases, arterioles in that region ______ and then react by ______.
Local metabolic factors
*Ex. During exercise, decreased O2 and increased CO2 levels in skeletal muscle tissues cause vasodilation -> now more blood will be directed to skeletal muscle for increased delivery of O2, etc.
______ occurs through the myogenic response and through local metabolic factors. 1) The ______ is how arterioles maintain constant blood flow under regular conditions. It is an intrinsic, built-in response that is mediated by the ______ in the arterioles. 2) ______ also impact arteriole diameter to produce vasoconstriction or vasodilation. In most tissues, blood flow is tightly coupled to ______.
Autoregulation maintains ______ blood flow over a range of perfusion pressures.
Sympathetic ANS nerves
As long as the demand for flow doesn't exceed the pumping capacity of the heart, then individual tissue beds can function ______. However, if tissue demands exceed flow, then ______ regulatory mechanisms are used to redistribute flow to prevent loss of blood pressure. These mechanisms include: ______ and ______.
Arteriole diameter can also be influenced by ______ factors (sympathetic ANS).
Slow rate of blood flow
Extensive network of thin-walled vessels that allow for rapid diffusion of molecules and are typically 1 mm long = ______. Most cells in the body are within 0.02 mm of a capillary. This ______ facilitates diffusion. ______ of capillaries also facilitates diffusion; typically only one-cell thick. ______ through capillaries also facilitates diffusion. Capillaries are part of the ______: arterioles -> capillaries -> venules.
Arteriole diameter (large or small)
Precapillary sphincters (open or closed)
Capillaries ______ surrounded by smooth muscle. In between the arterioles and capillary is a small cuff of smooth muscle called ______. Blood flow through capillary beds is usually ______ because precapillary sphincters are either open or closed. Relaxation and contraction of precapillary sphincters is called ______ and is influenced by metabolic state of tissue. 2 main factors regulate blood flow through capillaries: 1) ______ 2) ______
*Soluble = plasma membrane
Insoluble = pores
Capillary wall consists entirely of ______ (no smooth muscle). Small ______ exist between endothelial cells that allow passage of molecules. ______ and ______ vary among tissues. These make up a ______ % of capillary surface area. Exchange of molecules also occurs across the ______ of endothelial cells. ______ of a molecule will determine if and how it is transported (via pores or across the endothelium)
Exchange of water and dissolved solutes through pores also depends on ______ in response to a ______. The direction that fluid moves at the capillaries depends on the difference between the net ______ pressure and the net ______ pressure.
______ pressure is the force exerted by the fluid pressing against a wall (a "pushing" force): ______ hydrostatic pressure = pressure of blood in capillary that typically pushes fluid out of the capillary (______), especially at the arterial end, which has higher pressure compared to venule end. ______ hydrostatic pressure = pressure of interstitial fluid that technically pushes fluid into the capillary, except it's difficult to measure and often assumed to be zero.
Colloid osmotic (oncotic)
______ pressure is the force that will retain fluid in a compartment (a "pulling" force): ______ oncotic pressure = osmotic pressure of capillary due to plasma proteins, primarily ______ that favors retention of fluid in capillary (______) and is consistent across length of capillary. ______ oncotic pressure = osmotic pressure of interstitial fluid due to small protein concentrations that favors retention of fluid in interstitium.
______ end = fluid squeezed out of capillary by blood pressure. ______ end = fluid reentering capillary by osmotic attraction.
Hydrostatic = pushing
Oncotic = pulling
Filtration = Pc, piIF
Absorption = PIF, piP
Net filtration pressure = (Pc+piIF) - (PIF +piP). Pc = capillary hydrostatic pressure (pressure pushing water out of capillaries). piIF = interstitial fluid oncotic pressure (proteins in interstitium pull water out of capillaries). PIF = interstitial fluid hydrostatic pressure (pressure that pushes water into capillaries assumed to be 0). piP = plasma oncotic pressure (plasma proteins pull water into the capillaries).
*Total oncotic pressure = plasma oncotic pressure (28 mmHg) - interstitium oncotic pressure (3 mmHg). Therefore, net oncotic pressure of 25 mmHg facilitates absorption.
*At the arteriole end, hydrostatic pressure = 35 mmHg while at the venule end, hydrostatic pressure = 15 mmHg
______ = the balance between oncotic and hydrostatic pressure determines if filtration or absorption will occur in capillary. At the arteriole end: hydrostatic pressure ______ net oncotic pressure, so fluid will move out of capillary (______). At the venule end: hydrostatic pressure ______ net oncotic pressure, so fluid will move into capillary (______).
Net filtration pressure
Starling's hypothesis only applies to fluid movement at ______. Fluid movement depends on ______.
______ will increase blood flow and increase pressure, which favors filtration. ______ will decrease blood flow and decrease pressure, which favors absorption.
______ represent beginning of venous system. Veins are a ______ pressure system and can accommodate ______ change in volume with ______ change in internal pressure. Veins are ______ vessels. At any one time, about 61% of total blood volume is found in systemic veins, compared with 11% in systemic arteries.
Skeletal muscle contraction
Veins can ______ capacity through contraction of smooth muscle in the walls which occurs in response to ______ activation and results in transfer of blood from veins to heart and arterial system. ______ resistance encountered in the venous system. Some veins contain one-way ______ to contribute to flow of blood back to heart. ______ also facilitates blood flow back to the heart.
when walls of veins weaken, diameters can increase; valves separate and no longer prevent the backflow of blood; vein becomes enlarged, swollen, and twisted
Taken back up
Lymphedema (edema = accumulation of fluid in interstitial space)
*No cure for lymphedema, but may be controlled through compression garments, massage, and maybe even liposuction
Fluid that filters out of capillaries at arteriole end is typically ______ at venule end. However, about 15% is carried through ______, which filters fluid/lymph and dumps it back into systemic circulation. Like capillaries, lymphatic vessels consist of a ______ layer of cells. Vessels drain into larger vessels, which eventually drain into the ______ vein. Lymph vessels are ______ vessels. Blockage of lymph vessels results in ______.
Factors precipitating edema: 1) increased ______ pressure (as occurs when venous pressures become elevated by gravitational forces, in heart failure or with venous obstruction) 2) decreased ______ pressure (as occurs with hypoproteinemia during malnutrition) 3) increased ______ caused by proinflammatory mediators or by damage to the structural integrity of capillaries so that they become more "leaky" (as occurs in tissue trauma, burns, and severe inflammation) 4) ______ (as occurs in filariasis or with tissue injury)
*CO = MAP/TPR
MAP = CO*TPR
CO = SV*HR
Body monitors and maintains ______. Regulating this provides means to adjust ______ to meet blood flow requirements for tissues. ______ = total resistance to blood flow from aorta back to right atrium. Most ______ comes from arterioles and precapillary sphincters. Changes in TPR are due entirely to changes in ______ of these vessels. Constriction of small veins and venules contributes ______ to TPR because diameter of these vessels is much larger than diameter of arterioles.
Strength of contraction
CO = SV*HR. SV is influenced by ______ (determines how hard ventricles contract i.e. ______ and depends on ______ i.e. how well does blood get returned through veins to right atrium?). SV is influenced by ______ (influenced by sympathetic and parasympathetic activation). ______ is also influenced by sympathetic and parasympathetic activation.
CO*TPR = MAP. TPR depends on ______ (influenced by ______ nerve activation, ______ factors, and ______ (stretch response). MAP can influence: Myogenic activity -> influences ______ and capillary filtration/absorption -> total blood volume -> EDV -> ______.
Cardiovascular control center
______ are found in wall of aortic arch and in carotid sinus, a thin-walled, highly innervated region of the carotid artery in the neck. The nerve endings function as ______. When stretched, these receptors ______ rate of action potential firing. Increased MAP -> stretching of nerve endings -> increase AP firing -> APs are sent to neurons in ______ of medulla. Receptors respond quickly to changes in ______.
Nerve activity = AP firing. The frequency of AP firing ______ as MAP ______.
______ nerves from baroreceptors travel to brain and synapse with neurons in cardiovascular control center in medulla. Input leads to changes in ______ nerve activity to heart and vasculature. Increased rate of baroreceptor AP firing will ______ rate of sympathetic stimulation and ______ rate of parasympathetic stimulation. Decreased baroreceptor activity would do the ______.
Anatomy of Lungs. Two-tree-like structures: 1) ______ consists of arteries, veins, and capillaries. Blood is supplied through ______ circulation. 2) ______ consists of a series of hollow branching tubes that ______ in diameter with each branching or generation.
*Trachea, bronchial tree, bronchioles, terminal bronchioles
*Respiratory bronchioles, alveolar sacs
The airway tree is divided into 2 zones: 1) ______: warms, humidifies air; distributes air to deeper part of lungs; provides defense by removing dust, bacteria. 2) ______ is where gas exchange occurs.
Ventilation, gas exchange, gas transport, gas exchange, cellular respiration
Overview of respiration. 1) Ventilation: exchange of air between atmosphere and alveoli by bulk flow. 2) Exchange of O2 and CO2 between alveolar air and blood in lung capillaries by diffusion. 3) Transport of O2 and CO2 through pulmonary and systemic circulation by bulk flow. 4) Exchange of O2 and CO2 between blood in tissue capillaries and cells in tissues by diffusion. 5) Cellular utilization of O2 and production of CO2
Alveolar capillary membrane (found in respiratory zone). Gases diffuse along their ______ gradients.
______ = pressure that each individual gas would exert if it were present alone. ______ = pressure exerted by normal atmosphere. At sea level = 760 mm Hg. ______: Total pressure = sum of individual partial pressures of gases in atmosphere (PB = PN2+PO2+PH2O+PCO2). ______ occurs due to changes in partial pressure (similar to concentration gradient).
True or False. Gas diffusion occurs based on partial pressure gradients.
In the blood, oxygen is transported by binding to ______. Each Hb molecules can bind ______ oxygen molecules. When PO2 is high (in alveoli), O2 binds to the heme group in Hb to form ______. When it reaches the tissues, where PO2 is low, then O2 is ______ (released).
Loads rapidly with O2
Increases and loading slows
As PO2 increases in midrange, Hb ______. As Hb becomes saturated with oxygen, PO2 ______.
*Shift to right facilitates unloading
Shift to left facilitates loading
At low pH, Hb binds O2 with less affinity; Ex. during exercise, muscle produces more CO2 and lactic acid, pH of tissue drops
In the blood, CO2 is linked to ______ balance. Recall that enzymes function within a certain ______ range; blood pH is tightly regulated. CO2 diffuses from tissues into ______ circulation and is carried in three forms: 1) ______ 2) ______ 3) ______.
Bicarbonate ion (HCO3-)
CO2 transport. 1) 60-70% of CO2 is transported as ______. CO2+H2O -(carbonic anhydrase)-> H2CO3 -(dissociates)-> H+HCO3-. H+ ______ in the RBC and combines with Hb. HCO3- ______ from RBC into plasma (bicarbonate ion is how most CO2 is transported in blood). When HCO3- diffuses into the plasma, ______ replaces it by diffusing from plasma to RBC. This is accomplished by facilitated diffusion and is referred to as the ______.
Dissolved in plasma
CO2 transport. 2) ~25% of CO2 is transported as ______ inside the RBC; loose bond, easily reversed in lungs. 3) ~7% of CO2 is simply ______.
Regulation of breathing is based on ______ demands. Increased metabolism? Muscle makes ______ CO2 and ______ O2 intake. Must ______ ventilation to get rid of CO2. ______, ______, and ______ influence ventilation rate. Of these, ______ is most powerful stimulus; can increase ventilation 15-fold
______ detect changes in PO2, PCO2, and [H+]. ______ are found in medulla; respond only to changes in [H+] in cerebral spinal fluid (CSF). ______ are located outside of CNS; they respond to changes in PO2, PCO2, and [H+]. ______ = chemoreceptors located in aortic arch. ______ = chemoreceptors in carotid artery. When stimulated, chemoreceptors send action potentials to respiratory center of medulla, which then regulates ______ and ______ of ventilation through multiple mechanisms
low-pressure system; less resistance than systemic circulation; accommodates entire cardiac output
Congestive heart failure
Pulmonary edema (accumulation of fluid in the air sacs i.e. alveoli in the lungs)
During ______, left ventricle cannot adequately eject blood, and blood backs up into pulmonary circulation. This "backed up blood" is under ______ pressure because right side of heart is still pumping into pulmonary circulation. Increased capillary hydrostatic pressure favors filtration along length of capillary (Starling's Law), producing ______. One treatment for CHF is a diuretic + digitalis.
Angiotensin converting enzyme (ACE)
*Angiotensin I -(ACE)-> angiotensin II
In addition to being important for ______, pulmonary circulation has ______ function i.e. endothelial cells can act on a number of substances. ______ (an inactive protein) travels in blood and reaches lungs, where it is converted to ______ by an enzyme, ______, located on lung endothelial cells. ______ is then delivered to systemic arterioles -> causes vasoconstriction -> ______ blood pressure. ACE inhibitors are a class of drugs that lower blood pressure.
*Vena cavae -> RA -> LA -> LV -> aorta -> systemic circulation
*Vena cavae -> RA -> RV -> pulm trunk -> aorta -> systemic circulation
Before birth, lungs have no ______. Fetus depends on mother for ______ at placenta. Two unique structures allow blood to bypass lungs: 1) ______ = shunt between right and left atrium (~50% blood). ______ = shunts blood from pulmonary trunk to descending aorta (~40% blood). About 10% of fetal blood travels to lungs by ______ route.
Patent ductus arteriosus (PDA)
Normally the ______ closes after birth. Likewise, a few hours after birth, the ______ constricts and closes the vessel. Fibrous tissue (______) grows over next few months, causing permanent closure. If ductus arteriosus does not close, then it is called ______: causes a ______ of blood from aorta to pulmonary artery; ______ aortic pressure causes pulmonary hypertension; can lead to ______ damage to pulmonary arteries
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