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224 CSN > ch 21 blood vessels/circulation > Flashcards

ch 21 blood vessels/circulation Flashcards

1
Q

Name the 4 functions of the blood vessels

A
  1. carry blood and substances.
  2. exchange nutrients, wastes, and gasses with tissues.
  3. regulate blood pressure.
  4. directs blood flow to tissues.
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2
Q

Name the 7 vessel types that blood travels thru when it leaves the heart.

A
  1. Elastic arteries.
  2. Muscular arteries.
  3. Arterioles.
  4. Capillaries.
  5. Venules.
  6. Small veins.
  7. Medium and large veins.
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3
Q

As arteries get smaller what happens to the amount of elastic tissue and smooth muscle?

A

The elastic tissue gets less and less and the smooth muscle increases.

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4
Q

What happens to the walls of veins as they get bigger?

A

The walls get thicker

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5
Q

what is the histology of capillaries?

A

endothelial cells on a basement membrane

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6
Q

Name the 3 different types of capillaries and rate them from least amount of exchange to most.

A
  1. Continuous capillaries: 2 types. Some have no gaps (in brain, balls, and thymus) so these exchange the least. Then there are some with tiny gaps for minimal exchange.
  2. Fenestrated Capillaries: have fenestrations that only small things can get thru like hormone proteins.
  3. Sinusoidal Capillaries: large fenestrations and gaps for maximal exchange. Present in bone marrow and liver.
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7
Q

What feeds a capillary network?

A

metarteriole

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8
Q

What is the purpose of a precapillary sphincter?

What is the purpose of a thoroughfare channel?

A
  1. precapillary sphincters regulate capillary blood flow
  2. Thoroughfare channels connect metarterioles and venules, allowing blood to go directly to the venule if the precapillary sphincters are closing off the capillaries.
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9
Q

What are the 3 layers of blood vessel walls from deep to superficial and what are they made of?

A
  1. Tunica Intima: endothelium, basememnt membrane, lamina propria, and internal elastic membrane.
  2. Tunica Media: smooth muscle to control blood flow and external elastic membrane.
  3. Tunica Adevntitia: connective tissue that anchors to surrounding structures.
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10
Q

What are the 3 types of arteries?

A
  1. Elastic (conducting): Largest with most abundant elastic fibers. Pulse felt here. Collagen fibers limit stretch.
  2. Muscular (distributing): made of thick layer of smooth muscle and internal elastic membrane
  3. Arterioles: Have only 1-2 layers of smooth muscle and no elastic. Conduct blood to capillaries.
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11
Q

What are the 4 types of veins?

A
  1. Venules: collect blood from capillaries. Have a little smooth muscle. allow some exchange.
  2. Small veins: continuous layer of smooth muscle and tunica adventitia
  3. Medium and large veins: have all 3 tunics
  4. Portal veins: transport blood from one capillary bed to another. Only 2 portal systems in body, the hypohyseal portal system and hepatic portal system.
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12
Q

Large veins in the lower limbs and trunk have …………… to prevent backflow of blood.

A

valves

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13
Q

Increasing blood viscosity of vessel length does what to resistance?

A

it increases it

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14
Q

What happens to resistance and blood flow if we reduce the diameter of the vessel it is moving thru?

A

it increases the resistance and reduces the flow

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15
Q

What is critical closing pressure?

A

The pressure in a blood vessel below which the vessel collapses and blood cannot get thru.

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16
Q

According to Laplace’s law, as the diameter of a vessel increases, the force applied to the vessel wall ………… . This can cause what to happen to aneurysms?

A

increases. It can cause aneurysms to rupture

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17
Q

What is pulse pressure? what are the 2 factors that influence pulse pressure and how? Who typically has the greatest pulse pressure? What can a high pulse pressure mean?

A

The difference between systolic and diastolic pressures.

  1. Stroke Volume is directly proportional to pulse pressure. If SV increases, so does pulse pressure.
  2. Vascular Compliance is inversely related to pulse pressure. If vascular compliance increases, pulse pressure decreases.
  3. Elderly because vessels are less compliant.
  4. Hardening of the arteries.
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18
Q

what is the most important way that capillary exchange occurs?

A

osmosis

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19
Q

what are the factors that influence the movement of fluid from capillaries into the tissues?

A

blood pressure, capillary permeability, and osmosis

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20
Q

what is Net Filtration Pressure (NFP)?

A

The total force moving material into and out of capillaries. It is net hydrostatic pressure - net osmotic pressure.

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21
Q

what is edema?

A

edema is swelling. It is when a capillary becomes more permeable and proteins escape into the interstitial fluid, drawing more fluid with them because of osmotic pressure.

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22
Q

What are the vasa vasorum? Why do we have these?

A

small arterioles, capillaries, and venules that serve the walls of arteries and veins that are larger than 1mm. The smooth muscle layer needs nourishment to be able to contract.

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23
Q

What is Arteriosclerosis? What causes it?

A
  1. Hardening of the arteries. It reduces elasticity. It reduces blood flow and makes the heart work harder.
  2. Caused by old age. Caused by hypertrophy of the internal elastic membrane and tunica media. Collagen fibers can eventually replace smooth muscle.
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24
Q

What is Atherosclerosis? What causes it?

A
  1. A serious type of arteriosclerosis. Deposition of material in walls of medium and large arteries. Macrophages that have ingested cholesterol form plaques in tunica media and interna and reduces internal diameter of vessel.
  2. Caused by age and certain risk factors
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25
Q

What is laminar flow and turbulent flow?

A

Laminar flow: Concentric layers of smooth flow. Slowest on outside, fastest in center.
Turbulent flow: eddys, whorls ect where flow is interrupted or goes around a corner or obstruction.

26
Q

Blood flow through a vessel is ……………….. proportional to the pressure difference down the vessel and …………………. proportional to the resistance. Show the formula and explain.

A

directly. Indirectly. Flow=(P1-P2)/R
If the pressure difference (P1-P2) down a vessel increases, the blood flow will also increase. If the resistance (R) to flow goes up, the blood flow will go down.

27
Q

How is blood viscosity increased? Is this a common occurrence?

A

if the amount of hematocrit (the percentage of blood volume that is red blood cells) Normal amount of hematocrit is 40-55%. It rarely changes.

28
Q

How does vessel length change?

A

if we gain or lose a significant amount of weight

29
Q

What is the most common way the body regulates blood flow in a vessel?

A

changing the diameter of the vessel

30
Q

what is vascular compliance? What vessels are most compliant? Which vessels store more blood?

A

the ability of a vessel to increase in diameter with an increase of pressure. Thin walled veins. Veins store about 64% of total blood volume.

31
Q

What is the main job of the systemic circulation?

A

to regulate blood flow to provide adequate blood flow to the tissues. Same job as the heart

32
Q

What is the total cross-sectional area for each blood type? What does this mean? How does this relate to the velocity that blood travels?

A

it is the number of the type of blood vessel multiplied by the average cross sectional area. For example: the aorta= 5cm^2 and the capillaries = 2500cm^2. So capillaries have a much greater cross sectional area even though the aorta is a much larger vessel than any one capillary.

Velocity is faster in vessels where the cross sectional area is less example, water rushes through a narrow gorge (the aorta) yet slows down on a flood plain (capillaries)

33
Q

The velocity of blood is fastest in the ……………….. and slowest in the ……………. and speeds up again (but not as fast) on the way back to the …………

A

aorta, capillaries, heart

34
Q

Blood pressure pulses in the …………… . It stops pulsing as …………….. and smooths out in the …………….. . That is why we spurt blood when we cut an …………… .

A
  1. aorta and largest arterioles.
  2. vessels get smaller
  3. veins
  4. artery
35
Q

Resistance to flow is greatest in the …………………., which show the greatest ……………. in blood pressure.

A

arterioles, decline.

36
Q

True or false? Some material can move through endothelial cells. Give an example.

A

True. O2 and CO2 because they are non-polar and can diffuse through a cells membrane.

37
Q

Explain hydrostatic pressure and what it does.

A

Hydrostatic pressure is generated by the heart (blood pressure). It pushes fluid out of a vessel. It is higher than osmotic pressure at the arterial end of a capillary and pushes fluid out into the interstitial fluid.

38
Q

Explain osmotic pressure and what it does.

A

Osmotic pressure is generated by proteins in the blood. It pulls fluid back into the vessel. It is higher at the venous end of the capillary and returns 90% of fluid back into veins.

39
Q

What is venous tone? How can changes in venous tone affect the heart?

A

a continual state of partial contraction of the veins as a result of sympathetic stimulation.

Changes in sympathetic stimulation of the veins (ie: venous tone) will affect the heart’s preload, which affects SV and CO.

40
Q

if blood volume changes, venous return changes which affects ………………

A

preload

41
Q

How does gravity affect blood pressure? What aggravates/helps this situation? What is orthostatic hyportension?

A
  1. It increases blood pressure in lower limbs while standing.
  2. Skeletal muscle contractions can help pump blood upwards (walking). Standing without walking will aggravate situation.
  3. lightheadedness caused by a sudden drop in blood pressure when you stand up too quickly. Happens more in people who have low blood pressure. Deep breathing helps.
42
Q

What is an example of local control of blood flow in tissues? What causes precapillary sphincters to relax?

A
  1. Precapillary sphincters contracting/relaxing to change vessel size. Also known as vasomotion.
  2. metabolism in tissues releases vasodilator substances that cause sphincters to relax.
43
Q

What are some examples of vasodilator substances?

A

CO2 (byproduct of aerobic resp), lactate (byproduct of anerobic resp.), adenosine, AMP, ADP, endothelium derived relaxation factors, K+ (for cardiac muscle), and H+

44
Q

How does the body adapt to long-term demands for blood flow?

A

It changes the amount of capillaries and their density. For example, lots of weight gain would force the body to make more capillaries.

45
Q

What is autoregulation in regard to local blood flow control?

A

The maintenance of relatively constant blood flow by tissues despite the wide range of changes in arterial blood pressure. It is achieved by vasomotion (the opening an closing of precapillary sphincters).

46
Q

How can the body make widespread changes to circulation, as well as changes to areas of the body during exercise or extreme blood loss?

A

Through nervous and hormonal control by the sympathetic nervous system.

  1. nervous = action potentials sent to smooth muscles
  2. Hormonal = NE and E sent to receptors on smooth muscle
47
Q

The sympathetic fibers that control blood vessels and smooth muscles are located in the vasomotor center in the ……………. . The sympathetic division can change blood pressure and blood flow ………………… .

A

medulla. quickly.

48
Q

What is vasomotor tone?

A

The sympathetic division sending frequent action potentials to smooth muscle in vessels to keep the continually partially constricted. Increased frequency will cause full on vasoconstriction.

49
Q

Which part of the cerebral cortex can alter vasoconstriction? (the hypothalmus can too)

A

the limbic system (think emotions)

50
Q

Describe the sympathetic division’s hormonal control of the body’s vasculature.

A

NE and epinepherine bind to smooth muscle receptors to prolong the effect that the neurological control started. If if vessels have:
Alpha receptors + norepinephrine = constriction
Beta receptors + epinephrine = dilation

51
Q

Why is it important for the body to maintain MAP?
What is MAP’s usual pressure?
What is the equation for MAP?

A
  1. We must keep our MAP regulated in a good range because it makes it possible for the body to match blood flow to area’s specific needs. If MAP is too low, we go into circulatory shock. Too high damages vasculature.
  2. Less than halfway between systolic and diastolic pressures.
  3. MAP= COxPR = HRxSVxPR (remember CO is HRxSV)
52
Q

What are the 4 types of short-term regulation of BP?

A
  1. Baroreceptor reflex = minute to minute (but will adapt to new norm if the situation doesn’t change
  2. Adrenal Medullary Mechnism = takes a few seconds to start, but lasts minutes
  3. Chemoreceptor Reflex = primarily a respiratopry response to co2
  4. CNS’s Ischemic Response = extreme measure meant to preserve brain and heart in emergency.
53
Q
  1. Where are baroreceptors located?
  2. What do they detect?
  3. How does the frequency of their signal relate to the response?
  4. What aspects of MAP are afected?
A
  1. walls of aorta and carotid.
  2. They detect changes in BP and send action potentials (frequency increases when BP goes up).
  3. Increased frequency will decrease sympathetic and increase parasympathetic and vice versa
  4. affects HR, SV, PR which in turn affects MAP
54
Q

What triggers the Adrenal Medullary Mechanism? What are the percentages of NE and Epinephrine?

A

Large decreases in BP or physical activity. It is a longer response than the baroreceptor reflex which is only meant for minute to minute adjustments.
80% epinephrine, 20% NE

55
Q

What happens when neurons in the medulla sense dangerously low blood flow, decreased O2, pH, or increased CO2?

A

CNS’s Ischemic response. Vasoconstriction and increase of BP. Near death experience. Differs from chemoreceptor reflex in that it is not for minor adjustments, but near death.

56
Q

chemoreceptors are located where? What do they respond to?

A

aorta, carotid and medulla. Changes in pH, CO2, and O2. This is a very common response delivering routine maintenance.

57
Q

What are the 3 Long-term regulation mechanisms of BP, and how long do they last?

A

Take hours to kick in, but last for days or longer:

  1. RAAS mechanism: increases BP
  2. ADH hormone: increases BP
  3. Atrial Naturietic Peptide: lowers BP
58
Q

Describe the RAAS mechanism:

A
  1. low blood pressure causes kidneys to release Renin
  2. Renin converts angiotensinogen (from liver) into angiotensin 1.
  3. Lungs convert angiotensin 1 into angiotensin 2.
  4. Angiotensin 2 causes vasoconstriction and triggers release of Aldosterone by adrenal cortex.
  5. Aldosterone reduces water lost to urine by increasing Na+ Cl in kidney, hence restoring blood volume which increases blood pressure.
59
Q

Describe ADH mechanism. What’s another name for ADH?

A

Aka vassopressin. Triggered by high solutes in interstital fluid and low BP.

  1. ADH released from posterior pituitary causes water to be retained by kidneys.
  2. Vasoconstrictor, but not as strong as angiotensin 2.
60
Q

Describe the artial naturietic peptide (hormone) response:

A
  1. Triggered by high BP when atrial cells are stretched too much
  2. ANP causes vasodilation and increased Na+ Cl loss from kidneys so you pee more and reduce blood volume.
61
Q

What is the fluid shift mechanism?

A

a body response to high blood pressure that forces fluid out of capillaries into interstitial fluid to lower blood pressure. Body-wide edema. Imagine how you get puffy after a high sodium meal.

62
Q

What is the Stress-relaxation response?

A

when smooth muscle cells in vessels are stretched, they will relax. This is to bring blood pressure down. When BP needs to be raised, they will contract.

224 CSN (13 decks)

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