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AP2 > The Cardiovascular System: Blood Vessels > Flashcards

The Cardiovascular System: Blood Vessels Flashcards

1
Q

Blood vessels definition

A

Delivery system of dynamic/changing structures that begins and ends at the heart

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2
Q

What are the three types of blood vessels and their functions

A

a. Arteries: carry blood away from the heart; oxygenated except for pulmonary circulation and umbilical vessels of a fetus
b. Capillaries: contact tissue cells and directly serve cellular needs
c. Veins: carry blood toward the heart

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3
Q

Name the layers of arteries and veins and type of cells present

A

a. Lumen- blood-containing space
b. Tunica interna (intima)- epithelial
c. Tunica media- smooth muscle
d. Tunica externa- connective tissue

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4
Q

Name the layers of capillaries and type of cells present

A

a. One layer of endothelium only

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5
Q

Name the function of each Tunica layer

A

a. Tunica interna- responsible for angiogenesis
b. Tunica media- sympathetic vasomotor nerve fibers control vasoconstriction and vasodilation of vessels
c. Tunica externa- Collagen fibers protect and reinforce

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6
Q

Describe Elastic (Conducting) Arteries (description, location, and function)

A

a. Large, thick-walled arteries with elastin in all three tunics
b. Located in aorta and its three major branches
c. Large lumen offers low-resistance
d. Act as pressure reservoirs- expand and recoil as blood is ejected from the heart

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7
Q

Describe Muscular (Distributing) Arteries (description, location, and function)

A

a. Have thick tunica media- active in vasoconstriction
b. Distal to elastic arteries
c. Deliver (feed) blood to body organs

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8
Q

Describe Arterioles (Resistance Vessels)

A

a. Smallest arteries
b. Lead to capillary beds
c. Flow into capillary beds IF pre-capillary sphincters are opened

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9
Q

Describe Capillaries (Exchange Vessels)

A

a. Microscopic blood vessels
b. Walls of thin tunica intima, one cell thick (for diffusion)
c. Only one RBC can pass at a time
d. In all tissues, except cartilage, epithelia, cornea, and lens of eye
e. Function: exchange of gases, nutrients, wastes, hormones, etc

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10
Q

Describe capillary beds (description, location, and function)

A

a. Interwoven networks of capillaries allow flow between arterioles and venules
b. Precapillary sphincters regulate blood flow into true capillaries
c. Contains vasculary shunts and true capillaries (10-100 exchange vessels per bed)

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11
Q

What are the two Vascular shunts in capillary beds? What is their function?

A

a. Metarteriole
b. Anastomosis
c. Directly connects the terminal arteriole and a postcapillary venule to provide alternate pathways to a given body region

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12
Q

Describe the venules (formation and function)

A

a. Formed when capillaries unite
b. Venules flow together (confluence) to form the larger veins
c. Drains vein waste

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13
Q

Describe the veins (Capacitance Vessels) (description, formation, BP, lumen)

A

a. Formed when venules converge
b. Have thinner walls, larger lumens compared with corresponding arteries
c. Blood pressure is lower than in arteries (no pump)
d. These capacitance vessels (blood reservoirs) contain up to 65% of the blood supply

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14
Q

How do veins ensure return of blood to the heart?

A

a. Large-diameter lumens offer little resistance

b. Valves prevent backflow of blood and are most abundant in veins of the limbs

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15
Q

What is blood flow (F)? How is it measured?

A

a. Volume of blood flowing through a system in a given period
b. Measured as ml/min

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16
Q

What is blood pressure (BP)? How is it expressed? What is its purpose?

A

a. A pushing force (hydrostatic pressure) exerted on the wall of a blood vessel by the blood
b. Expressed in mm Hg
c. The pressure gradient provides the driving force that keeps blood moving from higher to lower pressure areas

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17
Q

What is peripheral resistance (PR)? Relationship to blood flow, blood viscosity, total blood vessel length, blood vessel diameter

A

a. Opposition to flow
b. Measure of the amount of friction blood encounters
c. PR is 1/α to flow
d. PR is α to blood viscosity
e. PR is α to total blood vessel length
f. PR is 1/α blood vessel diameter

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18
Q

What are blood resistance factors that remain relatively constant?

A

a. Blood viscosity- The “thickness” of blood due to formed elements
b. Blood vessel length- The longer the vessel, the greater resistance

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19
Q

What are blood resistance factors that are not constant?

A

a. Blood vessel diameter frequency changes- (resistance varies inversely with the fourth power of vessel radius- if the radius is doubled, the resistance is 1/16 as much)

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20
Q

Increased blood pressure results when?

A

a. Flow is opposed by resistance

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21
Q

Describe blood pressure in the aorta

A

a. Highest in the aorta
b. Declines throughout the pathway
c. Steepest drop in the arterioles (many pathways)
d. 0 mm Hg in the right atrium

22
Q

What is the top and bottom number when reading blood pressure?

A

a. Top is systolic pressure

b. Bottom is diastolic pressure

23
Q

What is systolic pressure?

A

a. Pressure exerted during ventricular contraction

24
Q

What is diastolic pressure?

A

a. Lowest level of arterial pressure during ventricular relaxation

25
Q

What is normal capillary blood pressure range?

A

a. 15-35 mm Hg, about 20

26
Q

What would high blood pressure do to capillaries?

A

a. Rupture fragile capillaries

b. Capillaries are permeable, so low pressure forces exudate into interstitial spaces

27
Q

Describe venous blood pressure

A

a. Changes little during the cardiac cycle
b. Small pressure gradient, about 15 mm Hg
c. Low pressure due to cumulative effects of peripheral resistance

28
Q

What factors aiding venous return?

A

a. Respiratory “pump”: pressure changes created during breathing moved blood toward the heart
b. Muscular “pump”: contraction of skeletal muscles slowly push blood toward the heart
c. Vasoconstriction of veins under sympathetic control (smooth muscle peristalsis)

29
Q

What helpers maintain blood pressure?

A

a. Heart, blood vessels, kidneys, supervision of by the CNS

30
Q

Describe the Vasomotor Center (location, physiology)

A

a. Part of the medullary cardiovascular center
b. Cluster of sympathetic neurons that oversee changes in blood vessel diameter
c. Receives inputs from baroreceptors and chemoreceptors (Co2 + acids)

31
Q

Where are baroreceptors and chemoreceptors located?

A

a. Carotid sinuses
b. Aortic arch
c. Walls of large arteries of neck and thorax

32
Q

Describe baroreception

A

a. Increased blood pressure inhibits the vasomotor center, causes vasodilation, and stimulates the cardioinhibitory center

33
Q

Describe chemoreception

A

a. Chemoreceptors respond to rise in CO2, drop in pH or O2 (when you’re about to die)
b. Increase blood pressure via the vasomotor center and the cardioacceleratory center (by heart beating faster)
c. **more important in the regulation of respiratory rate
d. Increase in Co2+H2O in lungs leads to rise in H2CO3 (carbonic acid) leading to H++HCO3 (hydrogen ions + carbonate ions)

34
Q

What hormones affect BP?

A

a. Norepinephrine, epinephrine
b. R-A-A pathway (vasoconstriction)
c. Antidiuretic Hormone (vasoconstriction)

35
Q

Describe the direct renal mechanism

A

a. Alters blood volume independently of hormones

b. Increased BP or blood volume causes the kidneys to eliminate more urine and vice versa

36
Q

Name/describe three ways to monitor circulatory efficiency

A

a. Vital signs: pulse and blood pressure, along with respiratory rate and body temperature
b. Pulse: pressure wave caused by the expansion and recoil of arteries
c. Radial pulse: routinely used and taken by the wrist

37
Q

How is systemic arterial BP measured?

A

a. Measured indirectly by the auscultatory method using a sphygmomanometer (cuff)
b. Pressure is increased in the cuff intil it exceeds systolic pressure in the brachial artery (120-200 mm Hg)
c. Pressure is released slowly, examiner listens for sounds of Korotkoff with stethoscope

38
Q

When do sounds of Korotkoff first occur and disappear?

A

a. First occurs as blood starts to spurt through the artery (systolic pressure, normally 110-140 mm Hg)
b. Sounds disappear when the artery is no longer constricted and blood is flowing freely (diastolic pressure, normally 70-80 mm Hg)

39
Q

What are some variables that affect blood pressure?

A

a. 24 hour cycle
b. BP peaks in the morning due to hormones
c. Age, sex, weight, race, mood, and posture

40
Q

What is hypotension? What is it associated with?

A

a. Low blood pressure
b. Systolic pressure below 100 mm Hg
c. Often associated with a long life and lack of cardiovascular illness

41
Q

Name and describe 3 types of hypotension

A

a. Orthostatic hypotension: temporary low BP and dizziness when suddenly rising from sitting or reclining position
b. Chronic hypotension: hint of poor nutrition and warning sign for Addison’s disease or hypothyroidism (prolonged symptoms)
c. Acute hypotension: important sign of circulatory shock

42
Q

What is hypertension?

A

a. High blood pressure

b. Sustained arterial pressure of 140/90 or higher

43
Q

When might hypertension occur?

A

a. May occur during fever, physical exertion, and emotional upset
b. Often persistent in obese people

44
Q

Blood perfusion (exchange) in body tissues is involved in what?

A

a. Delivery of O2, removal of wastes
b. Gas exchange (lungs)
c. Absorption of nutrients (digestive tract)
d. Urine formation (kidneys)

45
Q

Rate of flow is precisely what amount?

A

a. Right amount to provide for proper function

46
Q
  1. Describe capillary hydrostatic pressure (HP)
A

a. Tends to force fluids through the capillary walls
b. Is greater at the arterial end of the bed than at the venule end
c. Since H2O leaks out, appears there are more blood particles on the venule end

47
Q

What is circulatory shock? What does it result in?

A

a. Any condition in which blood vessels are inadequately filled or blood cannot circulate normally
b. Results in inadequate blood flow to meet tissue needs

48
Q

Name and describe three types of circulatory shock

A

a. Hypovolemic shock (most common): results from large-scale blood loss
b. Vascular shock: results from extreme vasodilation and decreased peripheral resistance (lose pressure)
c. Cardiogenic shock: results when an inefficient heart cannot sustain adequate circulation (fluttering or can’t cause circulation)

49
Q

Name and describe the two circulatory pathways

A

a. Pulmonary circulation: short loop that runs from the heart to the lungs and back from the heart
b. Systemic circulation: long loop to all parts of the body and back to the heart

50
Q

Name the fetal shunts and purpose

A

a. Foramen ovale and ductus arteriosus bypass nonfunctional lungs

AP2 (11 decks)

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