Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
66 Cards in this Set
- Front
- Back
|
Name the 5 general types of blood vessels in the cardiovascular system.
|
- Arteries - away from heart
- arterioles - feed into capilary beds - capillaries - venules - veins - towards heart |
|
|
Describe the general difference(s) between the sytemic and pulmonary circulation.
|
Pulmonary circuit - veins are oxygenated, arteries deoxygenated
Systemic circuit - veins are deoxygenated, arteries are oxygenated |
|
|
Name from innermost to outermost the three distinct tissue layers (i.e. tunics) of the blood vessel walls.
|
- tunica interna/tunica intima
- tunica media tunica adventitia |
|
|
Describe the general composition of each of the tissue layers of the blood vessel walls from innermost to outermost.
|
- tunica interna - simple squamous ET (flat and slick); subentothelial layer present in bigger vessels to support this ET with loose CT and a basement membrane
Tunica media - elastic fibers and sheets of smooth muscle; innervated by SNS; exhibits vasomotor tone; vasoconstricts and dilates Tunica adventitia - thin layer of CT; loosely woven collagen fibers; protects and anchors to surrounding tissue; has nerve fibers, lymphatic vessels, elastin fibers |
|
|
Which layer of the blood vessel wall is continuous with the endocardium of the heart?
|
- tunica interna
- contains the endothelium - flat cells fit together with endocardial lining of heart |
|
|
What effect does the sympathetic nervous system have on vascular smooth muscle tone?
|
- controls vasoconstriction and vasodilation
|
|
|
Identify the three basic types of arterial vessels and describe the structural differences between them.
|
Elastic/conducting arteries - aorta + big branches; tons of elastic fibers in their tunica media; large lumen for low resistance
Muscular/distributing arteries - distribute blood to specific body organs; smaller, thickest relative tunica media; more muscular than elastic arteries Arterioles - conduct blood from arteries to capillaries; tunica media very muscular for size; few elastic fibers; |
|
|
Identify the three basic types of arterial vessels and describe the functional differences between them.
|
Elastic/conducting arteries - function as pressure reservoir: during diastole, fibers contract to keep press on blood and push if forward
Muscular/distributing arteries - control blood supply to specific areas; ability to vasoconstrict/vasodilate Arterioles - blood to capillary beds; can vasoconstrict/dilate and control min to min amt. of blood flow into capillary beds; BIG rold in mean arterial press b/c so many of them |
|
|
Which areterial vessels serve as a pressure reservoir between contractions of the ventricles?
|
- elastic/conducting arteries
- during diastole, fibers gradually contract; keeps press on blood so it moves forewards - gives smooth/consistant blood flow to organs |
|
|
Which arterial vessels help to distribute blood to specific body organs or regions of the body?
|
- arterioles
|
|
|
Why are the arterioles called the resistance vessels of the vasuclar system?
|
- play a big role in mean arterial press b/c so many of them
- lots of surface area, so create a lot of afterload/resistance to the heart |
|
|
Which arterial vessels play the most important role in regulating blood flow into capillary beds and in regulating blood pressure?
|
- arterioles
- metarterioles - smallest arterioles, are vascular shunt; has precapillary sphincters that decide if blood flow through true capillaries or through the shunt (the metarteriole) - these changes dictate the blood press as well (more capillaries open will create more press) |
|
|
Identify and describe the arterial vessels which directly supplies a capillary bed.
|
- metarteriold formes thoroughfare channel from arteriole to post-capillary venule
- smallest arteriole - has precapillary sphincters that surround each capillary entry, opening/closing it |
|
|
What role do the precapillary sphincters play in regulating blood flow to the capillaries?
|
- surround the entry into each true capillary
- when closed, flood flows through shunt instead of through true cap. - allows local factors to affect the blood flow - typically blood flows intermittantly through capillary bed, since we don't have enough blood volume to fill all at once - respond to tissue hypoxia by relaxing |
|
|
What is the relationship between a metarteriole and a thoroughfare channel?
|
- metarteriole is continuous with the thoroughfare channel
- together, they form the vascular shunt - metarteriole is the part generally on the arterial side |
|
|
What is the relationship between the metabolic activity of a tissue and the number of capillaries it contains?
|
- higher metabolic activity overall will have more capillaries b/c they need more Oxygen
|
|
|
Identify and describe the structure of the three types of capillaries.
|
- Continuous capillaries - continuous tube; tight junctions join adjacent cells; found in skin and muscles; have intercelluar clefts except in brain, where the tight jcts form the blood-brain barrier
Fenestrated capillaries - contain pores; permit rapid exchange of water and small solutes b/w blood and interstitial fluid; found in small intestine, endocrine organs, kidneys Sinusoids - large irregularly shaped lumen; VERY leaky walls; passage of large molecules (hepatic macrophages etc) and blood cells; blood flows very slowly; allows time for modification of the blood; found only in liver, bone marrow, spleen and adrenal medula |
|
|
Identify and describe the structure of the major types of venous vessels.
|
- Venules - small, thin walled; all endothelium, very porous; post-capillary venules are the smallest; larger lumens
- veins - lumen larger than arteries, walls thinner; tunica media thin w/little smooth musc./elastin; tunica externa = thickest layer w/ collagen fibers and elastic networks; veins serve as blood reservoir |
|
|
Name the venules which directly drain the capillary beds.
|
- post-capillary venules
- the smallest type of venules - very porous (fluid and wbcs move easily) |
|
|
Which blood vessels serve as the blood reservoir?
|
- veins
- about 1/3 of blood in the veins at one time is considered the blood reservoir |
|
|
Why are the veins considered the capacitance vessels of the cardiovascular system?
|
- have large diameter
- can hold up to 65% of the body's blood supply - around 1/3 of the blood in the veins is considered the blood reservoir - when we need to use the blood reserve: for exercise or hemmorage etc |
|
|
What is the purpose of the valaves in the veins?
|
- maintains blood flow even in low pressure
- prevents backflow - valves out in arms/legs - when muscles contract - moves toward heart, can't backflow b/c of valves! |
|
|
Identify the forces which help move materials into and/or out of the capillaries.
|
- Diffusion - solutes move down conc. gradients towards equilibrium
- Filatration - movement of fluids through semi-permeable membrane due to hydrostatic pressure - Osmosis - created in a fluid by the presence of non-diffusible solutes |
|
|
What passive transport process accounts for the exchange of dissolved gases and nutrients in the capillary beds?
|
- diffusion
- each solute moves independantly of the others - have mostly reached equilibrium before the blood gets to the venous side of the cap. bed |
|
|
What processes account for the movement of fluid into and/or out of the capillaries?
|
- filtration - movement due to hydrostatic pressure (capillary hydrostatic pressure CHP); plasma forced across cap. wall when higher than interstitial fluid hydrostatic pressure (IFHP); highest at arterial end of cap bed
- Osmosis - press created in fluid by presence of non-diffusible solutes (the plasma proteins) |
|
|
What are the specific factors that promote filtration in the capillaries?
|
- filtration = fluid movement from capillaries to interstitium:
- Capillary hudrostatic pressure ( the press that a fluid creates against the walls of its container) - Interstitial fluid osmotic pressure (less than blood osmotic pressure, so H2O drawn out into tissue) |
|
|
What are the specific factors that promote reabsorption in the capillaries?
|
Reabsorption = fluid movement from interstitium to capillaries
- Blood colloid osmotic pressure (also called oncotic pressure; created by plasma proteins, and doesn't fall across bed b/c they can't diffuse out of cap.; helps pull water back in so H2O can flow back down its conc. gradient) - Interstitial fluid osmotic pressure - (when there are fewer non-diffusible solutes here than in blood, the h2O is drawn back in...) |
|
|
Define and be able to calculate net filtration pressure ( you do not need to memorize values for each of the terms in the equation, but know how to use values supplied in a test problem).
|
Net Filtration Pressure (NFP) = (forces that promote filtration: BHP + IFOP) - (forces that promote reabsorption: BCOP + IFHP)
- usually more leaves the capillaries than returns to them - this formula is Sterling's Law |
|
|
Define blood flow.
|
- Q
- the volume of blood moved through a vessel, an organ, or the entire circulation (systemic or pulmonary) per unit time - L/min for systemic; mL/min for an organ |
|
|
Define blood pressure.
|
- BP
- the force exerted (per unit area) by the blood against the inner walls of the blood vessels - measure the systemic BP in large arteries near the heart |
|
|
Define peripheral resistance.
|
- R
- the force that opposes movement - most of the resistance to blood flow occurs in the peripheral circulation - total peripheral resistance (TPR) = resistance in entire peripheral circulation |
|
|
Describe how each of the following factors affects peripheral resistance: blood viscosity, vessel length, vessel diameter.
|
Blood viscosity - blood cells make blood viscous; constant factor; why polycythemia makes blood circulation hard
Blood vessel length - longer = more resistance; direct relationship; big diff b/w systemic and pulmonary circuits; constant factor Blood vessel diameter - most important factor influencing TPR; resistance inversely proportional to 4th power of radius |
|
|
What is delta P (triangle in front of P)? How does delta P influence blood flow?
|
- the pressure gradient in the C-V system; causes blood flow
- no pressure gradient = no blood flow - positive value = positive flow |
|
|
Which blood vessels play the most important role in determining peripheral resistance? Explain your answer?
|
- arterioles - use VD/VC to change radius of vessels
- changes peripheral resistance |
|
|
Describe how pressure varies across the vascular system? Where is pressure lowest? Highest?
|
- pressure highest at arteries during systole, lowest in veins during diastole
- in capillarie veds, the NFP (net filtration pressure) is positive at the arterial end, and negative at the venous end of the capillaries (this isn't the same as real pressure though....) |
|
|
How are blood flow, blood pressure and peripheral resistance related to eachother?
|
Goal of circulation - to maintain adequate blood flow (Q)
- Q = press gradient/total systemic resistance - the pressure gradient must overcome the resistance to create positive blood flow in the C-V system |
|
|
Define systolic blood pressure (SBP), diastolic blood pressure (DBP), and pulse pressure (PP).
|
SBP - highest press acheived in arteries during systole; tells us how hard the heart has worked and how much strain is affecting the artery walls
DBP - measured during diastole; arteries contracting, sustaining press until right before next heart ejection; tells us how easy it was for blood to be pushed through arteries to arteioles to capillaries PP - the diff. in press b/w systolic and diastolic pressure (120/80 = PP of 40) |
|
|
What adaptations enable blood to continue flowing through the veins towards the heart, in spite of the low blood pressure in the veins?
|
- structural features of the veins themselves (the valves)
- respiratory pump - the diaphragm pushes blood in the abdomen, which increases BP; sends it up towards heart - Skeletal muscle pump - squeezing of muscles increases BP and forces blood up |
|
|
How do changes in cross-sectional area affect the velocity of blood flow? At which level of the vascular tree is the velocity of blood flow lowest?
|
- velocity of flow varies inversely to the total cross-sectional area of vessels at any given level of the vascular tree
- further away from heart = greater total cross-sectional area - aorta 4 cm, capillaries 5000 cm - slows blood down - ensures that blood continues to flow up veins towards heart; also helps diffusion across vessels |
|
|
Define mean arterial pressure (MAP) and tell why it is important.
|
- continual press - the average arterial pressure
- press that keeps blood flow continuous in the system - 99-100 mm Hg - should be less than 100 |
|
|
Given an SBP and a DBP, be able to calculate MAP
|
- mean arterial pressure
- MAP = DBP + 1/3PP - MAP = CO x TPR - note: PP = SBP-DBP and CO = HR x SV |
|
|
Identify the three factors which influence mean arterial pressure.
|
Cardiac output (CO) - = HR x SV; (SV influenced by catecholamines from adrenal medula; venous return affected by respiratory pump and vasoconstriction); (HR influenced by decreased parasympathetic impulses and increased catecholamines)
- Total peripheral resistance (TPR) - increased by: decreased blood vessel radius; total blood vessel length (body size); blood viscosity (from polycythemia with more rbcs) - Blood Volume - varies directly with MAP (mean arterial pressure); hydration level, hemmoraging; maintained through hormones |
|
|
How are mean arterial pressure, cardiac output and total peripheral resistance related to eachother?
|
- MAP = CO x TPR
- the pressure builds as the heart pumps more blood through the system, and as the resistance increases from the friction between more rbcs and more/smaller piping (vessels) - also, if you're trying to maintain a MAP, then if your cardiac output drops, you may try to maintain the pressure by vasoconstriction to increase the TPR |
|
|
How do variations in heart rate and stroke volume influence mean arterial pressure?
|
HR x SV = CO
- the cardiac output is one of the three major factors in MAP (also TPR blood volume) - the faster the heart pumps, and the more blood it pumps per beat, clearly the more pressure is going to be generated in the arteries |
|
|
Name and describe the location of the major components (i.e. sensory receptors, integration center, motor neurons, effector) of the reflex arcs which help regulate blood pressure.
|
- sensory receptors - baroreceptors found in aortic arch and carotic siunses; chemoreceptors found in aortic and carotid bodies
Integration center - the vasomotor center; found in the medulla Motor neurons - Sympathetic nervous fibers Effectors - vascular smooth muscle found in blood vessels and in the heart |
|
|
Describe the baroreceptor-initiated reflex for control of blood pressure.
|
- mechanoreceptors in aortic arch and carotid sinuses
- BP inc; dilation/stretch of baroreceptors; more AP's fired and sent to medula; inhivition of vasomotor center in medulla; vasodilation caused by dec. SNS outflow and Co decrease caused by increase PNS outflow = BP decrease, backwards for increase |
|
|
What stimulus causes baroreceptor activity to increase?
|
- stimulated by increase in BP
- stretches the baroreceptors, and makes them fire more APs to the medulla |
|
|
What effect does increased baroreceptor activity have on the vasomotor center? on vascular smooth muscle?
|
Vasomotor center - inhibited by the increased APs from the baroreceptors
Vascular smooth muscle - vasodilation because of a decrease in SNS outflow from the medulla - leads to decreased blood pressure |
|
|
Explain the effects on blood pressure of the following factors: catecholamines, ADH.
|
Catecholamines:
- Epinepherine increases TPR by inc. vasoconstriction - Norepinepherine increases CO by increasing HR and contractility ADH (vasopressin): vasoconstricting effect; causes water reabsorption in kidneys |
|
|
Explain the effects on blood pressure of the following factor: renin-angiotensin-aldosterone system.
|
RAAS - (a mechanism of aldosterone regulation from the zona glomerulosa of the adrenal cortex); increases BP; renin from kidney catalyzes angiotensinogen from liver into antiotensin I; angiotensin I converted by angiotensin converting enzyme (ACE) in lungs to angiotensin II; vasoconstricts and stimulates cortex to secrete aldosterone
- angiotensin II is a powerful vasoconstrictor; aldosterone reabsorbs Na, also influences water reabsorption in the kidneys when in the presence of ADH |
|
|
Explain the effects on blood pressure of the following factor: atrial natriuretic peptide (ANP).
|
- another regulator of aldosterone secretion
- released by atrial cells when stretched by inc. venous return - inhibits ADH and aldosterone; causes Na to go oout in urine - decreased blood volume and increased vasodilation = dec. BP |
|
|
baroreceptor
|
primary component of the MAP regulation reflex arc
- measures pressure |
|
|
chemoreceptor
|
secondary component of the MAP regulation reflex arc
- measures H+ (an indicator of pH), CO2, H2O |
|
|
cariotic sinus
|
- where baroreceptors are located
- common corotid where it branches into the internal and external carotid arteries |
|
|
carotid body
|
- where the chemoreceptors are located
- found hear the carotid sinus |
|
|
aortic body
|
- where chemoreceptors are found
- A receptor area in the wall of the aortic arch near the heart sensitive to levels of carbon dioxide, oxygen, and pH in the blood |
|
|
pulse pressure
|
- the difference in press b/w systolic and diastolic press.
- ex. BP of 120/80 makes a PP of 40 - used to calculate MAP: = DBP x 1/3 PP |
|
|
edema
|
abnormal accumulation of interstitial fluid
- bruise, swelling - leakage of plasma proteins - undernourished - a dec. of plasma proteins, so BCOP - edema in interstitium of lungs is a big problem |
|
|
vasomotion
|
- the regular constriction/relaxation of the precapillary sphincter
- makes flow slow through the bed - keeps the BP high, even though we don't have enough blood to fill all the beds at once - constricts 5-10 times/min |
|
|
sinusoid
|
- a type of capillary found only in the liver, bone marrow, spleen and adrenal medulla
- large irregularly shaped lume with very leaky walls - allows passage of large molecules and blood cells - blood flows very slowly through the sinusoids to allow time for the blood to be modified in whatever way |
|
|
fenestration
|
- pores found in endothelial cells of capillaries to make them more permeable
|
|
|
intercellular clefts
|
- unjoined membrane gaps that form gaps in the tight junctions of continuous capillaries
- just big enough to let limited fluids and small solutes through - don't exist in the brain, where the tight junctions are complete to form the blood-brain barrier |
|
|
vasomotor tone
|
- smooth muscle of the tunica media is innervated by the SNS part of the ANS
- vasomotor nerves regulate it - causes vasoconstriction/vasodilation |
|
|
Starling's Law
|
- defines the balance of net filtration pressure (NFP)
- NFP = forces that promote filtration (BHP + IFOP) - forces that promore reabsorption (BCOP + IFHP) - NFP positive at arterial end of c. beds and negative at venous end |
|
|
oncotic pressure
|
- BCOP/blood colloid osmotic pressure
- the osmotic pressure of the blood created by the plasma proteins - doesn't change over course of c. bed b/c plasma proteins are to big to get out of the blood generally |
|
|
anastomosis
|
a cross-connection between two blood vessels; an interconnection between any two channels, passages or vessels; the surgical creation of a connecting passage between blood-vessels or other channels
|
