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A And P 2 > pt 3 > Flashcards

pt 3 Flashcards

1
Q

List the three different type as of blood vessels in the human body.

A

Arteries, capillaries, and veins

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2
Q

Which of these vessels is the site of exchange between blood and interstitial fluid?

A

Capillaries

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3
Q

What gets exchanged through capillaries?

A

O2, CO2, nutrients, hormones, and waste

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4
Q

What important role do lymphatic vessels play?

A

Lymphatic system recovers the fluid that leaks from blood vessels

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5
Q

What are the three layers of each blood vessel wall from deepest to most superficial?

A

Tunica intima
Tunica media
Tunica externa

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6
Q

What is the vasa vasorum?

A

Vasa vasorum – a network of tiny blood vessels that nourish the vessel itself

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7
Q

Compare/contrast the anatomical structure of arteries and veins.

A

Veins don’t have internal and external elastic membranes in tunica intima and tunica media

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8
Q

What is the important functional role of the tunica media?

A

o Vasoconstriction = smooth muscle contracts and lumen decreases
o Vasodilation – smooth muscle relaxes and lumen increases

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9
Q

What are the 3 types of arteries?

A

o Elastic arteries
o Muscular arteries
o Arterioles

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10
Q

How do the 3 types of arteries compare in terms of size, structure and function?

A
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11
Q

For its size, which type of artery has the highest percentage of tunica media?

A

Elastic arteries

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12
Q

Describe the structure and function of a capillary bed. What tissues do NOT have a rich capillary supply?

A

Capillaries do not function independently – they form interweaving networks called capillary beds
o Microcirculation: how blood flows from an arteriole to a venule through a capillary bed
Gases, nutrients, hormones, and waste are exchanged during microcirculation
o In most body regions, a terminal arteriole branches into 10 to 20 capillaries – the capillary bed
o The capillary bed drains into a postcapillary venule

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13
Q

What are the three types of capillaries? Where could you find each type?

A

o Continuous: most common, least permeable
Abundant in skin, muscles, lungs, and the CNS
The structural basis of the blood-brain barrier
o Fenestrated: large fenestrations or pores increase permeability
Abundant in kidneys, small intestine, and areas of hormone secretion
o Sinusoid: occur in limited locations, the most permeable
Found in the liver, bone marrow, spleen, and adrenal medulla
Have large intercellular clefts and irregular shapes
Contain macrophages to catch prey

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14
Q

What’s an intercellular cleft?

A

Gaps of un-joined membrane are intercellular clefts

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15
Q

Define microcirculation

A

o Microcirculation: how blood flows from an arteriole to a venule through a capillary bed
Gases, nutrients, hormones, and waste are exchanged during microcirculation

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16
Q

Define terminal arteriole

A

In most body regions, a terminal arteriole branches into 10 to 20 capillaries – the capillary bed

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17
Q

Define postcapillary venule.

A

The capillary bed drains into a postcapillary venule

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18
Q

Describe the process of rerouting blood including vascular shunt, metarteriole, and precapillary sphincter.

A

o Vascular Shunt: a vessel that directly connects the terminal arteriole to the postcapillary venule – allows blood to bypass the true capillaries
o Shunt consists of a metarteriole and a throughfare channel
o As true capillaries branch from the metarteriole, each is surrounded by a cuff of smooth muscle called a precapillary sphincter
o Precapillary sphincters act as valves to regulate blood flow into the capillaries – they are controlled by chemical conditions

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19
Q

Why are veins called “blood reservoirs”? Define venule, vein, and venous sinus.

A

Secondary to larger lumens, veins can act as blood reservoirs – they can hold up to 65% of the body’s blood supply at any given time

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20
Q

What is a structural adaptation that improves blood’s ability to return to the heart via the veins?

A

Blood pressure in veins is much lower than in arteries – allowing for the veins’ thinner walls
Veins have one way valve that prevents blood from traveling back down the body when veins are carrying blood back to heart

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21
Q

What causes varicose veins?

A

o Varicose Veins: veins that are torturous and dilated secondary to incompetent/leaky valves
o 15% of adults experience varicose veins – typically, in superficial veins of the lower limbs
o Risk Factors: prolonged standing, obesity, pregnancy

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22
Q

What is an anastomosis? Why is this functionally important?

A

o Anastomosis: special interconnection between blood vessels
o Arterial Anastomoses: arteries supplying the same regions often merge and provide alternate pathways/collateral channels
If one arterial branch is lost, a collateral channel can provide sufficient blood to the region
Arterial anastomoses can be found around joints, abdominal organs, the heart, and the brain
Regions without redundancy: retina, kidneys, and spleen
o Venous Anastomoses: very common, an occluded vein rarely leads to tissue death

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23
Q

How does blood flow along a pressure gradient?

A

o Blood flows through the vessels on a pressure gradient – always from higher to lower pressure!
o The pumping action of the heart generates blood flow – resistance to flow generates pressure
o Systemic pressure is highest in the aorta and steadily declines
o Steepest drop occurs in the arterioles – where resistance is highest
o Pressure in the right atrium is 0mmHg

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24
Q

What is flow?

A

Flow – the volume of blood flowing through a vessel, organ, or circulation system in a period of time
Remains fairly constant and is relatively equivalent to CO

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25
Q

What is pressure?

A

o Pressure – the force per unit area exerted on a vessel wall by the contained blood
Typically measured in the largest arteries near the heart
The hydrostatic pressure gradient – the difference in bp within the vascular system – provides the driving force to keep blood moving

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26
Q

What is resistance?

A

o Resistance
Opposition to flow, the amount of friction that blood encounters
Most friction is encountered well away from the heart – total peripheral resistance TPR
Sources of resistance, blood viscosity, vessel length, and vessel diameter

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27
Q

What are three sources of resistance? Which of these is the most important in determining blood flow?

A

o Blood viscosity – internal resistance to flow that exists in all fluids
Thickness or stickiness of fluid
Greater viscosity – less movement
Blood viscosity is fairly constant – exceptions being the anemias and polycythemias
o Blood vessel length
Longer vessel = greater resistance
o Blood vessel diameter
Smaller diameter = greater resistance

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28
Q

How does blood pressure differ in arteries, capillaries, and veins?

A

Pressure is higher in arteries than capillaries and veins, gets lower
Venous pressure is far less pulsatile – pressure gradients are less steep
Low venous pressure results from TPR – energy has been dissipated out
Despite valves, venous pressure is too low for adequate venous return

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29
Q

In the process of moving from the aorta to the right atrium, where does blood pressure decrease the most?

A

arterioles

30
Q

What is the average blood pressure in the right atrium?

A

Pressure in the right atrium is 0mmHg

31
Q

What is SP?

A

Systolic – blood is expelled into the aorta, the walls are stretvched, aortic pressure peaks, avg. = 120 mmHg

32
Q

What is DP?

A

Diastolic pressure – aortic walls recoil, aortic valve closes, and pressure drops, avg. = 80 mmHg

33
Q

What is pulse pressure?

A

o Pulse pressure – the difference in systolic and diastolic pressure
increased SV and contractility can temporarily increase PP
atherosclerosis chronically increases pulse pressure

34
Q

What is MAP?

A

o MAP – the pressure that propels blood into the tissues- useful tool for determining tissue perfusion
DP + PP/3

35
Q

Know why MAP is a useful clinical tool. Why is MAP not just SBP averaged with DBP?

A

o Determines tissue perfusion
o Diastole lasts longer than systole, so MAP is not the halfway point btwn SBP and DBP

36
Q

What are the Sounds of Korotkoff?

A

Auscultatory Method: practitioner uses a sphygmomanometer and a stethoscope to listen to the Sounds of Korotkoff

37
Q

What is it more difficult for blood to make its return trip to the heart via the veins?

A

Venous pressure is too low for adequate venous return

38
Q

List the three functional adaptations for assisting blood to return to the heart via the veins.

A

Muscular pump, respiratory pump, and sympathetic vasoconstriction

39
Q

Be familiar with the relationships between CO, TPR, and blood volume.

A

o Blood pressure varies directly with CO and TPR
o Anything that increases CO or TPR will increase BP
o Anything that increases HR or SV will increases BP
o Any change that threatens BP homeostasis will be compensated for

40
Q

neural methods of short-term regulation of blood pressure

A

Maintain adequate MAP by altering blood vessel diameter – small changes in vessel diameter can cause substantial changes in TPR - and therefore BP
Example: perfusion of the heart and brain during low blood volume
Alter blood distribution to respond to specific demands
Example: during exercise, blood is shunted to the skeletal muscles
Most neural controls operate via reflex arcs involving baroreceptors
Baroreceptors, The cardiovascular center contains cardioacceleratory, cardioinhibitory, and vasomotor centers, vasomotor fibers, vasomotor tone, Net Result, chemoreceptors,

41
Q

hormonal methods of short-term regulation of blood pressure

A

Adrenal Medulla Hormones, Angiotensin II, Renin, Atrial Natriuretic Peptide (ANP), Antidiuretic Hormone (ADH)

42
Q

What do baroreceptors do as a neural method of short-term bp regulation?

A
  • Baroreceptors: pressure-sensitive mechanoreceptors that respond to changes in arterial pressure and stretch
  • Inputs from baroreceptors are integrated into the Cardiovascular Center of the medulla oblongata
  • Outputs travel via autonomic fibers to the heart and the vascular smooth muscle
43
Q

What is the brain;s cardiovascular center and its 3 parts as a neural method of short term bp regulation?

A
  • The cardiovascular center contains cardioacceleratory, cardioinhibitory, and vasomotor centers
    -The vasomotor center transmits impulses along sympathetic efferent fibers called vasomotor fibers
  • Vasomotor fibers exit the spinal cord (T1-L2) and innervate the smooth muscle of the blood vessels – mainly arterioles
  • Arterioles are almost always moderately constricted resulting in baseline vasomotor tone
  • Increased sympathetic activity will increase vasoconstriction and raise BP; decreased sympathetic activity will decrease vasoconstriction and lower BP
44
Q

What do chemoreceptors do as a neural method of short-term bp regulation?

A
  • Chemoreceptors: receptors that respond to changes in levels of CO2, H+, and O2 in the blood
  • Chemoreceptors stimulate the cardioacceleratory center to increase CO and the vasomotor center to increase vasoconstriction when:
  • CO2 level rises
  • pH level falls
  • O2 level falls
    Located close to the baroreceptors, the most prominent chemoreceptors are the carotid bodies and the aortic bodies
    Chemoreceptors play a larger role in regulating respiratory rate
45
Q

What is vasomotor tone?

A

Arterioles are almost always moderately constricted resulting in baseline vasomotor tone

46
Q

What is the effect of short term methods of bp regulation on high brain centers?

A

Reflexes regulating blood pressure are integrated into the medulla oblongata of the brain stem – the cerebral cortex and hypothalamus are not involved in routine regulation of BP
Higher brain centers can modify arterial pressure via relays to the brain stem
Examples: fight or flight response, redistribution of blood flow by the hypothalamus

47
Q

What does epinephrine and norepinephrine do as a hormonal method of short-term bp regulation?

A

Adrenal Medulla Hormones: Epinephrine and Norepinephrine
- Released in response to stress
- Enhance sympathetic response by increasing CO and promoting vasoconstriction

48
Q

What does renin and angiotensin II do as a hormonal method of short-term bp regulation?

A

Angiotensin II
- Renin is released by the kidneys when blood pressure or volume are low
- Renin generates Angiotensin II
- Promotes intense vasoconstriction to rapidly increase blood pressure
- Stimulates release of ADH and Aldosterone – both participate in longer term BP regulation

49
Q

What does Atrial Natriuretic Peptide (ANP)
do as a hormonal method of short-term bp regulation?

A

Atrial Natriuretic Peptide (ANP)
- Produced by the atria of the heart to reduce blood volume and pressure
- Antagonizes aldosterone, promotes vasodilation, stimulates excretion of sodium and water

50
Q

What do ADH do as a hormonal method of short-term bp regulation?

A

Antidiuretic Hormone (ADH)
- Also called vasopressin, produced by the hypothalamus
- Stimulates the kidneys to conserve water and widespread vasoconstriction

51
Q

What is long term bp regulation through renal mechanisms?

A

Longer term blood pressure controls regulate blood volume
What is the average human blood volume?
Increased BV = Increased BP and vice versa
The kidneys are a key player in long term regulation

52
Q

What is direct vs indirect renal mechanisms?

A

o Direct Renal Mechanism
When BV or BP rise, fluid is filtered from the bloodstream to the kidneys more rapidly -> increased urine -> decreased BV and BP
The opposite also occurs!
o Indirect Renal Mechanism
When BP declines, the kidneys release the enzyme renin into the blood
Renin splits the plasma protein angiotensinogen to make angiotensin I
Angiotensin I is converted to angiotensin II by angiotensin converting enzyme (ACE)
ACE is found in the capillary endothelium of various body tissues – especially the lungs

53
Q

What are The Four Actions of Angiotensin II?

A

The Four Actions of Angiotensin II
- Stimulates the adrenal cortex to secrete aldosterone
- Stimulates the posterior pituitary gland to secrete ADH
- Triggers the sensation of thirst
Vasoconstriction to increase TPR

54
Q

What is hypertension?

A

Hypertension (HTN): chronically elevated blood pressure
- SBP > 130 mmHg; DBP > 80 mmHg
30% of adults over 50 are hypertensive
- HTN strains the heart and damages the blood vessels
- Prolonged HTN is a major cause of heart failure, vascular disease, renal failure, and CVA

55
Q

What is primary hypertension?

A

Hypertension without a specific, underlying cause
Environmental, contributing factors:
- Heredity
- Diet
- Obesity
- Age
- Diabetes Mellitus
- Stress
- Smoking
- Primary HTN can be controlled with improved diet, increased exercise, stopping smoking, managing stress, and taking anti-HTN medications
- Commonly used anti-HTN medications: diuretics, beta-blockers, calcium-channel blockers, ACE inhibitors, and angiotensin II receptor blockers

56
Q

What is secondary hypertension?

A

10% of HTN cases
Secondary HTN as an identifiable cause:
- Obstructed renal arteries
- Kidney disease
- Endocrine disorders – hyperthyroidism or Cushing’s Disease

57
Q

What are the dangers of prolonged hypertension?

A

Heart failure, vascular disease, renal failure, and CVA

58
Q

What are the dangers of prolonged hypotension?

A

Hypotension is problematic when it results in inadequate tissue perfusion

59
Q

What is hypotension?

A

Blood Pressure < 90/60 mmHg
Often hypotension is harmless – or even healthy!
- Chronic hypotension can be a sign of a serious underlying condition
- Addison’s Disease: inadequate function of the adrenal cortex
- Hypothyroidism
- Severe malnutrition
- Hypotension is problematic when it results in inadequate tissue perfusion

60
Q

What are 3 types of circulatory shock?

A

o Hypovolemic Shock: blood volume is too low
o Vascular Shock: blood volume is normal; poor circulation because of extreme vasodilation and lost TPR
o Cardiogenic Shock: pump failure

61
Q

What is hypovolemic shock?

A

o Hypovolemic Shock: blood volume is too low
Results from large scale blood or fluid loss
HR will increase in response to a dramatic drop in blood volume
Intense vasoconstriction will shift blood out of reservoirs
Treatment: replace fluid volume ASAP

62
Q

what is vascular shock?

A

o Vascular Shock: blood volume is normal; poor circulation because of extreme vasodilation and lost TPR
Anaphylactic: lost vasomotor tone in response to an allergic reaction
Neurogenic: failure of the autonomic nervous system
Septic: severe systemic bacterial infection

63
Q

What is cardiogenic shock?

A

o Cardiogenic Shock: pump failure
Results from extensive myocardial damage – an inefficient heart

64
Q

What is circulatory shock?

A

Circulatory Shock: blood vessels are inadequately filled; blood cannot circulate normally – body tissues are not adequately perfused

65
Q

What is the overall function of the lymphatic system?

A

Returns the fluid leaked from the blood vessels back to the blood

66
Q

Because lymphatic vessels are ____________________ than blood vessels, they can be used as a route of transportation for pathogens and cancer cells.

A

Because lymphatic vessels are permeable than blood vessels, they can be used as a route of transportation for pathogens and cancer cells.

67
Q

What are the 2 largest lymphatic ducts called? What portion(s) of the body are drained by each of these ducts?

A

o Right lymphatic duct drains the RUE and R side of head/thorax
o Thoracic duct drains rest of body

68
Q

What are the 2 functions of lymph nodes?

A

o Cleansing lymph/acting as lymph filters
Macrophages remove or destroy microorganisms and debris
o Immune system activation
Offers a place for lymphocytes to become activated and mount an attack against antigens

69
Q

The tonsils, Peyer’s patches, and the appendix are all examples of MALT. What is the chief function of each of these tissues?

A

o Tonsils – gather and remove pathogens in food or air
o Peyer’s patches – destroy bacteria, prevent it from breaching the intestinal wall
Generate memory lymphocytes
o Appendix
Destroy bacteria, prevent it from breaching intestinal wall
* Generate memory lymphocytes

70
Q

What is venule?

A

Capillaries unite to form Venules:
8-100 µm in diameter
Postcapillary venules are the smallest venules – they are made entirely of endothelium meaning they are porous and “leaky”
Larger venules will have both tunicas media and externa

71
Q

What is a vein?

A

Venules merge to form veins
Veins have all three tunics, but thinner walls and a larger lumen than arteries
Veins have little elastin or smooth muscle in the tunica media
The tunica externa is thick with longitudinal bundles of collagen
Secondary to larger lumens, veins can act as blood reservoirs – they can hold up to 65% of the body’s blood supply at any given time
Blood pressure in veins is much lower than in arteries – allowing for the veins’ thinner walls

72
Q

What are venous sinuses?

A

Venous Sinus: a highly specialized, flat vein with extremely thin walls
Walls are made only of endothelium
Sinuses are supported by the structures around them – not additional tunics
Ex: coronary sinus, the dural venous sinuses of the brain

A And P 2 (14 decks)

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