Combo 19 1
Circulation of the pulmonary circuit?
*Arteries which deliver blood to the lungs -pulmonary trunk, left and right pulmonary arteries *Capillaries in the lungs where gas exchange occurs *Veins which deliver blood to the left atrium --four pulmonary veins
What are the 4 ways that capillary transport can take place?
1. Diffusion through membrane (lipid- soluble substance. 2. Movement through intercellular clefts (water soluble substance) 3.Movement through fenestration (water soluble- substance) 4. Transport via vesicles (large substances
List the Major factors that enhance cardiac output.
1. Exercise: 1) increases the respiratory pump, increases the muscular pump, and increases venoconstriction. 2) increases venous return 3) Increases end diastolic pressure 4) which increases stroke volume. 5) ends in an increased Cardiac output. 2) Decreased BP activates the cardiac centers in the medulla: decreased parasympathetic activity, and increased sympathetic activity. Both lead to an increase in Heart Rate. increased sympathetic activity> increased epinephrine in the blood> Increased contractility of cardiac muscle> increased End systolic volume> increased stroke volume> increased cardiac output.
Where does arterial blood pressure come from? When does it rise and fall?
1. Heart Pumping (Cardiac output) 2. contraction of the arterial smooth muscle cells 3. total blood volume 4. Blood viscosity Rises during ventricular systole and falls during ventricular diastole, which results in a pulse. If more blood flows tries to flow through the arterial system pressure will rise. remember that arterial pressure is blood pressure.
what are the functions of the peripheral circulation?
1. carry blood 2. exchange nutrients, waste, products, and gases. 3. Transport of hormones, components of the immune system, molecules required for coagulation, enzymes, nutrients, gases, waste products. 4.Regulate blood pressure (which can be accomplished because we have a closed circuit system) 5. Direct blood flow in the body.
What is Poiseuille's Law?
A law that explains that flow, pressure, and resistance are all related. F= Flow ∆P= Pressure R= Resistance F a ∆P/R When F is increased P will increase, R will Decrease R a ∆P/F F x R a ∆P According to Poiseuille's Law factors involved in the cardiovascular pressures include: Vessel Length- Longer the vessels the more more surface area in contact with the fluid, the more resistance. Vessel Diameter- total cross- sectional area of vessels Blood Viscosity- thickness of bloss and Turbulence also affects blood flow.
Which hormone release is stimulated by Angiotensin II?
Alderstone
which hormone is activated in response to falling BP ?
Angiotensin II
List and explain the factors that influence blood pressure, and describe how blood pressure is regulated.
Arterial blood pressure reflects two factors: How much the elastic arteries close to the heart can be stretched (their compliance or dispensability) The volume of blood forced into them at any time. If the amounts of blood entering and leaving the elastic arteries in a given period were equal, arterial pressure would be constant. Blood pressure rises and falls in a regular fashion in the elastic arteries near the heart. •Central among the homeostatic mechanisms that regulate cardiovascular dynamics are those that maintain blood pressure, principally cardiac output, peripheral resistance, and blood volume. Cardiac output (blood flow of the entire circulation) and peripheral resistance relate to blood pressure. o F = ΔP/R o CO = ΔP/R o ΔP = CO X R •blood pressure varies directly with CO and R.Additionally, blood pressure varies directly with blood volume because CO depends on blood volume (the heart can't pump out what doesn't enter its chambers). So in theory, a change (increase or decrease) in any of these variables would cause a corresponding change in blood pressure. However, what really happens in the body is that changes in one variable that threaten blood pressure homeostasis
Aging of Arteries
Arteriosclerosis: general term for degeneration changes in arteries making them less elastic Atherosclerosis: deposition of plaque inside of walls
Explain how blood flow is regulated in the body in general and in specific organs.
Autoregulation is the automatic adjustment of blood flow to each tissue in proportion to its needs, and is controlled intrinsically by modifying the diameter of local arterioles. •Metabolic controls of autoregulation are most strongly stimulated by a shortage of oxygen at the tissues. •Myogenic control involves the localized response of vascular smooth muscle to passive stretch. •Long-term autoregulation develops over weeks or months, and involves an increase in the size of existing blood vessels and an increase in the number of vessels in a specific area, a process called angiogenesis.
Cardiovascular regulation has 4 levels of regulation, what are they? What happens in each?
Autoregulation- occurs at the local tissue level -Local Vasodilators accelerate blood flow by causing relaxation of metarterioles and precapillary sphincter muscles. - Meets the tissues metabolic needs due to: --Decreased tissue O2 levels or increased CO2 levels --Generation of Lactic Acid --Rising K or H concentration in interstitial fluid -- Elevated temperature --Local inflammation -- Release of nitric oxide - Long term needs cause more capillary growth. Neural Mechanisms- Rapid response system -Minute to minute adjustments -Adjust Cardiac output and peripheral resistance to maintain vital organ blood flow. -Medullary centers of regulatory activity include: ---Cardiac centers ---Vasomotor centers control: ------Vasoconstriction: by way of adrenergic release of Epinephrine and Norepinephrine (NE) ------Vasodilation via Direct acetylcholine (Ach)or indirect release of nitrous oxide (NO) Endocrine Mechanisms- Slower response system Chronic Regulation- Kidney and fluid balance
Where is blood pressure the Highest? the lowest?
BP is 100-120 mm Hg in the aorta, and drops to near 0 mm Hg in the right atrium. BP is the pressure on the blood when the ventricle contracts.
If there is a decrease in TPR, what happens to BP?
BP will decrease leading to Hyoptension.
If there is an increase in TPR, what happens to BP?
BP will increased leading to hypertension.
Why is peripheral resistance the most important factor in influencing local blood flow?
Because vasoconstriction, and vasodilation can dramatically alter local blood flow while systemic blood pressure remains unchanged.
Define blood flow, blood pressure, and resistance, and explain the relationships between these factors.
Blood flow - is the volume of blood flowing through a vessel, an organ, or the entire circulation in a given period (ml/min). Blood pressure (BP)- the force per unit area exerted on a vessel wall by the contained blood, is expressed in millimeters of mercury (mm Hg). Resistance - is opposition to flow and is a measure of the amount of friction blood encounters as it passes through the vessels. Blood flow (F) is directly proportional to the difference in blood pressure (ΔP) between two points in the circulation, that is, the blood pressure, or hydrostatic pressure, gradient. Thus, when ΔP increases, blood flow speeds up, and when ΔP decreases, blood flow declines. Blood flow is inversely proportional to the peripheral resistance (R) in the systemic circulation; if R increases, blood flow decreases. These relationships are expressed by the formula F=∆P/R
If peripheral resistance increases, what will happen to blood flow?
Blood flow decreases
Circulatory pressure is divided into 3 components, what are they?
Blood pressure (arterial pressure) (BP)- reflects how much the arteries close to heart can be stretched, and the volume of blood forced into them at any given time. Capillary Hydrostatic pressure (CHP)- Is low ranging from 40-20 mm Hg, which protects the capillaries from rupture, but is still adequate to ensure exchange between blood and tissues Venous pressure (lowest pressure)- changes very little during the cardiac cycle, and is low, reflectionf the cumulatice effects of peripheral resistance.
What do Chemoreceptors reflexes monitor? What do they do?
CO2, O2, or pH levels found in carotid bodies, aortic bodies, and medulla oblongata detect a rise in CO2 levels of the blood, and stimulate the cardioacceleratory and vasomotor centers, which increases cardiac output and vasoconstriction.
Name the different parts of circulation and the corresponding % in the distribution of blood in the CV system?
Capillaries- 5% Heart- 8% Pulmonary blood vessels-12% Systemic arteries and arterioles -15% systemic veins and venules- 60%
What are the forces acting across capillary walls?
Capillary hydrostatic pressure (CHP) Blood colloid osmotic pressure (BCOP)- Oncotic pressure Interstitial fluid colloid osmotic pressure (ICOP) Interstitial fluid hydrostatic pressure (IHP)
Where is the most frequent site used to measure pulse rate?
Carpus with the radial artery which is called the radial pulse
What are some causes of Edema?
Chemicals of inflammation increase permeability Decreases in plasma concentration of protein reduces BCOP ---Liver disease resulting in fewer plasma proteins ---Loss of plasma proteins through the kidneys ---Protein starvation Blockage of veins increases capillary BP; reduced venous return due to gravity Blockage or removal of lymphatic vessels (blockage: elephantiasis; removal: cancer)
What 4 processes are involved in moving fluids across capillaries?
Diffusion - solutes going from an area of high concentration to low concentration Hydrostatic pressure (CHP) - blood pressure inside the capillaries. One of the driving forces for filtration. Filtration - is movement of water and its solutes across the endothelial barrier due to pressure Reabsorption - movement of fluid and solutes back into the capillaries.
Which artery plays a role in vasodilation or constriction determines blood flow to individual capillary beds?
Dilation or constriction of arterioles determines blood flow into individual capillary beds.
What are blood vessels?
Dynamic structures that pulsate, constrict, relax, and even proliferate.
Which artery's major role is in damping the pulsatile pressure of heart contractions?
Elastic arteries play a major role in in dampening the pulsatile pressure of the heart contractions.
Which hormone is released if BP falls or O2 levels are abnormally low?
Erythropoietin
Explain the difference in flow between a thoroughfare channel, and arterial capillaries. what regulates this flow?
Flow through a thoroughfare channel is fairly consistent, while flow through arterial capillaries is intermittent. Smooth muscle in arterioles, metarterioles, and precapillary sphincters regulate blood flow.
Hydrostatic pressure
Fluid moves based on force of compression (fluid against the wall)
Capillary facts.... no question just read.
For all capillary beds, 29 liters of fluid is filtered out per day - nearly 7x total plasma volume! (17 liters/day reabsorbed @ venous end) If capillaries become more permeable, proteins can leak into the interstitial fluid increasing ICOP. More fluid moves from the capillaries into the interstitial fluid: edema.
Define hypertension. Describe its manifestations and consequences.
Hypertension - high blood pressure, condition of sustained arterial pressure of 140/90 or higher, and the higher the pressure, the greater the risk for serious cardiovascular problems. •Causes Heredity. Hypertension runs in families. Children of hypertensive parents are twice as likely to develop hypertension as are children of normotensive parents, and more blacks than whites are hypertensive. Many of the factors listed here require a genetic predisposition, and the course of the disease varies in different population groups. Diet. Dietary factors that contribute to hypertension include high intakes of salt (NaCl), saturated fat, and cholesterol and deficiencies in certain metal ions Obesity. Age. Clinical signs of the disease usually appear after age 40. Diabetes mellitus. Stress. Particularly at risk are "hot reactors," people whose blood pressure zooms upward during every stressful event. Smoking.Nicotine •strains the heart and damages the arteries.Prolonged hypertension is the major cause of heart failure, vascular disease, renal failure, and stroke. Because the heart is forced to pump against greater resistance, it must work harder, and in time the myocardium enlarges.When finally strained beyond its capacity to respond, the heart weakens and its walls become flabby. Hypertension also ravages the blood vessels, accelerating the progress of atherosclerosis the vessels become increasingly blocked, blood flow to the tissues becomes inadequate and vascular complications appear in the brain, heart, kidneys, and retinas of the eyes.
Where does pressure change from pulsatile to continuous flow?
In capillaries and veins
Where does the greatest drop in pressure occurs?
In the arterioles which regulate blood flow through tissues.
Myogenic control What causes vasoconstriction, and vasorelaxation?
Increased stretch of vascular smooth muscle cells by high blood pressure causes a reactive vasoconstriction, which prevents organ damage. Decreased blood pressure causes Vasorelaxation, this permits aquate blood flow despite low driving pressure.
What are potent vasodilators?
Inflammatory chemicals, such as histamine, prostacyclin, and kinins are potent vasodilators.
endothelium- derived factors promote vasoconstriction, and released in response to what?
Low blood flow
Determining MAP, how do it?
MAP is the average blood pressure in the arterial tree MAP= CO x PR CO is the amount of blood pumped by the heart per minute CO= SV (stroke volume) X HR (heart rate) PR is the total resistance against which blood must be pumped So MAP= diastolic pressure + 1/3 pulse pressure (Systolic-Diastolic). Example: Systolic BP= 120 Diastolic BP= 90 Pulse pressure= (S-D) 120-90= 30 MAP= 90+(1/3 of 30) MAP= 90+ 10= 100
What dose VENOconstriction do? What is Venous reserve?
Maintains blood volume during a hemorrhage (smooth muscle in the vein can contract and make the lumen small to maintain blood volume) Venous reserve is the amount of blood that can recirculare after venoconstriction (mostly comes from liver,spleen, and the lungs.
What is MAP?
Mean Arterial Pressure, and is the average blood pressure of the arteries. Is determined by cardiac output (heart rate and stroke volume) and peripheral resistance (constriction of arteries)
What is Blood pressure?
Measure of force exerted by blood against the wall, and this pressure is what causes blood to move through vessesl.
How is blood pressure measures?
Measured by listening for korotkoff sounds, that are produced by turbulent flow in arteries as pressure is released from the blood pressure cuff.
How do muscular arteries, and arterioles contribute to control of pressures in the CV?
Muscular arteries and arterioles constrict or dilate to control blood pressure and regulate blood flow into specific regions of the body or tissues.
Which arteries have the thickest tunica media relative to their lumen size?
Muscular arteries have the thickest tunica media relative to their lumen size to account for the greater amount of smooth muscle.
Which hormone is released in response to excessive right atrial stretch?
Natriuretic peptide (ANP)
What is produces in response to high blood flow or other signaling molecules, and promotes systemic and localized vasodilation?
Nitric Oxide
Arteries undergo changes in diameter based on what 3 things?
Passive stretch in response to pressure (remember that the lumen of an artery can stretch as the volume of the blood pumped increases) Vasoconstriction- decreases the size of the lumen when pressure goes up Vasodilation- increases the size of the lumen as the pressure decreases.
The difference between systolic and diastolic pressure create the?
Pulse pressure
What can a pulse pressure be used to determine?
Pulse pressure can be used to determine the heart rate and rhythmicity of the heart.
Explain when pulse pressure tends to rise?
Pulse tends to increase when stroke volume increases or vascular compliance decreases. (BP normally rises with age because of compliance tends to decrease with are (arteriosclerosis- hardening of the arteries) and pressure rise)
What is the very basic structure of a capillaries, and what do they do?
Remember there are far more capillaries in the body than arteries, and veins. Capillaries have an endothelial tube inside of a basal lamina, and do not contain a smooth muscle cell layer or adventitia (tunica externa) Capillaries: Form networks, surround muscle fibers, and other tissues, radiate through connective tissues, and weave through active tissues. Capillaries also allow diffusion of O2, CO2, and other solutes between tissue and blood. This is the ONLY place where exchange of nutrients, respiratory gases, and waste products can occur.
what is the pulse?
Rhythmic pressure oscillation that accompanies each heart beat
In Neural Regulation of blood vessels which anatomic system of the CNS is most important? why?
Sympathetic division is most important because it innervates most arteries and veins. Sympathetic stimulation causes the output of NE/E from the adrenal medulla Results in vasoconstriction of vessels in skin and viscera by stimulation of alpha adrenergic receptors and causes vasoconstriction in skeletal muscle via beta adrenergic receptor stimulation.
List the locations where you can feel a pulse.
Temporal artery Facial artery Common carotid artery Brachial artery Radial artery Femoral artery popliteal artery Posterior tibial artery Dorsalis pedis artery
List 3 factors that determine resistance in a vessel. Which of these factors is physiologically most important?
The 3 factors that determine resistance in a vessel are blood viscosity, vessel length, and vessel diameter. Vessel diameter is physiologically the most important.
Describe the function and structure of a capillary bed.
The Capillary Bed also called the plexus in an interconnected network of vessels that allows high pressure blood from the arterial side to lower in pressure, and return to the heart by the venous side. Capillary beds provide a huge surface area for diffusion to occur across. They all have collateral arteries feeding in to an arteriole, which then will branch into capillaries or into metarterioles, which then branch into more capillaries and connect directly into more capillaries, and connect directly into venules. Each capillary has a precapillary sphincter muscle, which is a cuff of smooth muscle fibers and acts a valve to regulate blood flow into capillary. Can squeeze to restrict blood flow into the capillary, or open to allow blood flow into the capillary. Arteriovenous anastomoses- Which is the direct connection of an artery and vein (thoroughfare channel)
Special circulation of the brain, heart and lungs?
The brain Four arteries which anastomose ensuring constant blood flow The heart Coronary arteries arising from the ascending aorta The lungs Pulmonary circuit, regulated by local responses to O2 levels - low O2 causes vasoconstriction Opposite other tissues (declines in O2 cause vasodilation)
Describe the structure and function of a capillary bed, types of capillaries.
The microscopic capillaries are the smallest blood vessels. Their exceedingly thin walls consist of just a thin tunica intima, and they do not contain any smooth muscle. In some cases, one endothelial cell forms the entire circumference of the capillary wall. Capillaries allow for the exchange of substances between the blood and interstitial fluid, and is where the heavy lifting of the circulatory system is accomplished. types of Capillaries Continuous Capillaries (tunica intima is not full of holes, least permeable and most common)- abundant in the skin and muscles, are most common. They are continuous in the sense that their endothelial cells provide an uninterrupted lining, adjacent cells being joined laterally by tight junctions. Have tight epithelia that from barriers such as the blood brain barrier. They only allow passage of fluids and small solutes. Fenestrated Capillaries (swiss cheese, has large holes. This increases the permeability of the capillary, and occurs at sites of active absorption or filtration such as the kidneys, and small intestine.) are similar to the continuous variety except that some of the endothelial cells in fenestrated capillaries are riddled with oval pores, or fenestrations. The fenestrations are usually covered by a delicate membrane, or diaphragm (probably condensed basal lamina material), but even so, fenestrated capillaries are much more permeable to fluids and small solutes than continuous capillaries are. Sinusoids Capillaries (Most permeable have the largest holes, where small formed elements can leave from the blood into the tissue space) - are highly modified, leaky capillaries found only in the liver, bone marrow, and spleen where blood cells inter and leave the circulatory system (Important to note that the basement membrane is only incomplete in the sinusoidal capillary. Pericytes (smooth muscle like cells that stabilize the capillary wall) often occur in continuous capillaries.) •Terminal Arteriole - feeds the capillary bed •Metarteriole - a vessel structurally intermediate between an arteriole and a capillary •True Capillaries number 10 to 100 per capillary bed, depending on the organ or tissues served. They usually branch off the metarteriole •Precapillary Sphincter - surrounds the root of each true capillary at the metarteriole and acts as a valve to regulate blood flow into the capillary •Thoroughfare Channel - intermediate between a capillary and a venule. •Venules - are formed when capillaries unite. Postcapillary Venules - the smallest venules, consist entirely of endothelium around which pericytes congregate. They are extremely porous and fluid and white blood cells move easily from the bloodstream through their walls. The larger venules have one or two layers of smooth muscle cells (a scanty tunica media) and thin externa as well. •exchange of materials (gases, nutrients, hormones, and so on) between the blood and the interstitial fluid
For blood to flow, what must happen to the pressure gradient?
The pressure gradient must overcome total peripheral resistance.
Why can't pluse be taken from veins?
The pressure is too weak, and pressure is continuous.
Explain why we need pressure gradients in blood vessels?
The purpose of the cardiovascular system is to allow the exchange of solutes and other substances between the blood and tissues, therefore blood must flow through the tissues. In order for there to be an exchange between the blood space and the tissue space blood has to slow down so that diffusion can take place, because diffusion takes time. This is done by creating a pressure gradient that is HIGHEST in the ventricles and declines as it goes through the CV system, such that is LOWEST when it reaches the atria of the heart. ***Remember that Pressure is Highest in the Left ventricle, and lowest in the right atrium.
Suppose vasoconstriction decreases the diameter of a vessel to one-third its size, what happens to the rate of flow through the vessel? calculate the expected size change.
The rate will decrease 81 fold from its original flow (3x3x3x3=81)
Which layer of the blood vessel wall so sympathetic nervous of the autonomic nervous system innervate? What are the effector cells that carry out the response?
The sympathetic nervous innervate the tunica media
Which branch of the autonomic nervous system innervates blood vessels?
The sympathetic nervous system innervates blood vessels. The effector cells are the smooth muscle of the tunica media.
Where do blood vessels begin and end?
They are a closed system that begin and end at the heart
Explain why which vessel is the capacitance vessel?
To first understand why veins are capacitance vessels it's important to understand that capacitance is the relationship between blood volume and pressure which is the expandability of the vessel. Veins are called capacitance vessels and blood reservoirs because they can hold up to 65% of the body's blood supply at any given time, even so they are normally only partially filled. (more blood that is in the vein, the more pressure is exerted on the vein, the more the vein has to expand)
What is TPR?
Total peripheral resistance, is the resistance of the entire arterial system
Describe the three layers that typically form the wall of a blood vessel, and state the function of each.
Tunica Intima - the innermost tunic, in intimate contact with the blood in the lumen. This tunic contains the endothelium, the simple squamous epithelium that lines the lumen of ALL vessels. The endothelium is continuous with the endocardial lining of the heart, and its flat cells fit closely together In vessels larger than 1 mm in diameter, a subendothelial layer, consisting of a basement membrane(which is a cellular protein matrix) and loose connective tissue, supports the endothelium. forms a slick surface that minimizes friction as blood moves through the lumen. Tunica Mediais - the middle tunic, mostly circularly arranged smooth muscle cells and sheets of elastin, the bulkiest layer in arteries (may have connective tissue, and an external elastic membrane) chief responsibility for maintaining blood pressure and continuous blood circulation. The activities of the tunica media are critical in regulating circulatory dynamics because small changes in vessel diameter greatly influence blood flow and blood pressure. The tunica media can contract or relax to control the blood flow. When the tunic media is relaxed the lumen in larger, when the tunic media is contracted the lumen is smaller. Tunica Externa (also called the tunica adventitia) the outermost layer is composed largely of connective tissue (loosely woven collagen fibers and elsatin) The tunica externa also contains the vasa vasorum, which is a network of tiny blood vessels that feed the tunica media and tunica externa. protect and reinforce the vessel, and anchors it to surrounding structures
What is the function of venous valves? What forms the valves?
Valves are formed folds of the tunica intima, and are in veins to prevent the backflow of blood.
Resistance in vessels.
Vascular resistance or peripheral resistance is the resistance of an arterial bed. Resistance of the cardiovascular system opposes the movement of blood. Resistance is inversalatey to flow of blood.
Alcohol inhibits ADH and the Vasomotor center, resulting in what?
Vasodilation.
Which hormone is released in response to decreased blood volume or osmolarity?
Vasopressin (antidiuretic hormone- ADH)
Describe the structure and function of veins, and explain how veins differ from arteries.
Veins collect blood from all tissues and organs (via capillary beds), and return it to the heart. Veins are under a low pressure system and blood movement is not forced By the heart rather flows back to the heart muscular compression and the respiratory pump. •Veins usually have three distinct tunics, but their walls are always thinner and their lumens larger than those of corresponding arteries. •There is relatively little smooth muscle or elastin in the tunica media, which is poorly developed and tends to be thin even in the largest veins. The tunica externa is the heaviest wall layer. Consisting of thick longitudinal bundles of collagen fibers and elastic networks, it is often several times thicker than the tunica media. In the largest veins—the venae cavae the tunica externa is further thickened by longitudinal bands of smooth muscle. ( Walls of veins gradually thicken in progression from venules to large veins) •With their large lumens and thin walls, veins can accommodate a fairly large blood volume. Veins are called capacitance vessels and blood reservoirs because up to 65% of the body's blood supply is found in the veins at any time Venis are classified according to size Venules are formed where capillaries converge and allow fluid and white blood cells to move easily between the blood and the tissue (where veins and capillaries unite) lumens are 8-100 um in diameter. Medium sized veins (where venules join) lumens are 2-9mm in diameter. Large veins (where medium veins join) have lumens that are 9mm or larger. •Venous valves - are formed from folds of the tunica intima, and resemble the semilunar valves of the heart in both structure and function. They are found in venules and medium sized veins, and prevent the backflow of blood.
In the systemic circuit, which contains more blood? Arteries, veins, or is the amount the same?
Veins contain more blood than arteries in the systemic circuit, at 60%
Describe how venous pressure and return works?
Venous pressure and return works through the combined forces of The respiratory pump and muscular compression which both rely on the action of skeletal muscle. As muscles expand and contract the veins are squeezed and released pushing blood back up toward the heart. This is why the valves are needed to prevent backflow. This also means that inactivity of the skeletal muscle will reduce venous return to the heart. Muscular compression is the primary force, while the respiratory pump (Diaphragm-skeletal muscle) is the secondary force.
What is diastolic pressure?
When blood is prevented from flowing back into the ventricles by the closed semilunar valve, the aorta recoils and the diastolic pressure is made (70-80 mm Hg)
When vascular smooth muscle contracts, what happens to the diameter of the blood vessel? What is is this called?
When the vascular smooth muscle contracts, the diameter becomes smaller. This is called vasoconstriction.
What are varicose veins?
When valves become weakened and small veins become distended, The valve breaks down and blood will accumulate in that section of the vein.
Angiotensin II will?
Will cause an increase in Blood pressure by vasoconstriction, and as well as promote the release of aldosterone and ADH
Norepinephrine and epinephrine will?
Will cause an increase in Blood pressure by, promoting an increase in cardiac output and generalized vasoconstriction.
ADH
Will cause in increase in blood pressure due to vasoconstriction and increased blood volume from decreased water loss
Aldosterone will?
Will increase blood pressure by decreasing water a salt loss in the kidney tubules cells.
Compare and contrast the structure and function of the three types of arteries.
arteries distribute oxygenated blood to the body under high pressure, and do not have valves. ( pulmonary circulation is different arteries still defined as vessels leading away from the heart, carry oxygen poor blood to the lungs) •Elastic Arteries - called conducting, thick-walled arteries near the heart—the aorta and its major branches. These arteries are the largest in diameter (>0.5 cm)and the most elastic Large lumens make them low-resistance pathways that conduct blood from the heart to medium-sized arteries. They are relatively inactive in vasoconstriction (do not contract very strongly), they can be visualized as simple elastic tubes. Elastic arteries are pressure reservoirs, expanding and recoiling as blood is ejected from the heart. Consequently, blood flows fairly continuously (are there to take large volumes of blood and move it to a location, examples are the aorta, pulmonary artery, and first level branches) (contain large amounts of elastin, which enables these vessels to withstand and smooth out pressure fluctuations due to heart action) •Muscular Arteries - distributing arteries, distally the elastic arteries give way to the muscular, or distributing, arteries, which deliver blood to specific body organs and account for most of the named arteries studied in the anatomy laboratory. Their diameter ranges from 1-5 mm. Muscular arteries have the thickest tunica media of all vessels(because of the greater smooth muscle content for vasoconstriction, and vasodilation). Their tunica media contains relatively more smooth muscle and less elastic tissue than do elastic arteries active in vasoconstriction and less distensible. responsible for the regulation of blood pressure. •Arterioles - smallest of the arteries, Larger arterioles have all three tunics, but their tunica media is chiefly smooth muscle with a few scattered elastic fibers. Smaller arterioles, which lead into the capillary beds, are little more than a single layer of smooth muscle cells spiraling around the endothelial lining. Arterioles are resistance vessels with an internal diameter of 35um or less. They can regulate the blood flow in the capillaries through vasoconstriction and vasorelaxation. ** remember that size measurements refer to the lumen size**
What are the 3 major types of blood vessels?
arteries, capillaries, and venins
If blood pressure increases, what will happen to blood flow?
blood flow increases
What do chemical controls influence?
blood pressure by acting on vascular smooth muscle or the vasomotor system,
What so arterial baroreceptors monitor?
blood volume
What does peripheral circulation mean?
circulation out of the heart
What is the Vasomotor center?
cluster of sympathetic neurons in the medulla that controls changes in the diameter of blood vessels.
Vascular anastomoses?
form where vascular channels unite, allowing blood to be supplied and drained from an area even if one channel is blocked.
Blood resistance is the?
measure of the friction between blood and the vessel wall, and arises from 3 sources: blood viscosity, blood vessel length, and blood vessel diameter.
What do Baroreceptors reflexes monitor? What do they do?
monitor stretch in large arteries (carotid sinus and aortic sinus) detect stretch and send impulses to the vasomotor center, inhibiting its activity and promoting vasodilation of arterioles and veins
How can the hypothalamus and cortex modify arterial pressure?
signaling the medullary centers.
What is Pulse pressure?
the difference between systolic and diastolic pressure range between 120-80 mm Hg
What is blood flow?
the volume of blood flowing through a vessel, organ, or the entire circulation in a given period, and maybe expressed as ml/min
what is systolic pressure?
when the left ventricle contracts, blood is forced into the aorta, which produces a peak in pressure called the systolic pressure.(120 mm Hg)
Atrial natriuretic peptides (ANP) will?
will cause a decrease in blood pressure by acting as a vasodilator, also inhibits aldosterone resulting in a drop in blood pressure.
Describe how blood pressure differs in the arteries, capillaries, and veins.
•Any fluid driven by a pump through a circuit of closed channels operates under pressure, and the nearer the fluid is to the pump, the greater the pressure exerted on the fluid. The dynamics of blood flow in blood vessels is no exception, and blood flows through the blood vessels along a pressure gradient, always moving from higher- to lower-pressure areas. Arteries must be able to endure high pressure of blood, from the aorta to the ends of the arterioles is about 60 mm Hg Capillaries are fragile and high pressures would rupture them, and most capillaries are extremely permeable and thus even the low capillary pressure forces solute-containing fluids (filtrate) out of the bloodstream into the interstitial space. Venous blood pressure is steady and changes very little during the cardiac cycle. The pressure gradient in the veins, from venules to the termini of the venae cavae, is only about 15 mm Hg •Arteries receive blood from the heart, the blood they receive is under a lot of pressure. Can you picture how much pressure the arteries near the heart (like the pulmonary trunk and the aorta) have to withstand every time the ventricles squirt out a load of blood? At the same time, this pressure helps the blood move through the arteries-- even when the arteries are running in opposition to gravity •The veins only receive the blood after it has travelled quite far from the heart. The blood pressure in the veins is thus much less; the blood is certainly much less likely to burst through walls of the veins than arteries. Also, because the blood pressure is small in the veins, it is not going to be enough to return all that blood to the heart; in fact, the blood could easily back up or collect in these vessels
Define vasoconstriction and vasodilation
•Vasoconstriction - reduction in lumen diameter as the smooth muscle contracts •Vasodilation - increase in lumen diameter as the smooth muscle relaxes
