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Western Medicine 502 > Vascular System > Flashcards

Vascular System Flashcards

1
Q

Arteries

A

efferent vessels of the cardiovascular system. they are vessels that carry blood away from the heart.

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2
Q

veins

A

they are the afferent vessels. they carry blood back to the heart

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3
Q

capillaries

A

microscopic, thin-walled vessels that connect the smallest arteries to smallest veins

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4
Q

tunica intima/tunica interna

A

lines the inside of the vessels and is exposed to the blood. it consists of a simple squamous epithelium called the endothelium. the endothelium acts as selectively permeable barrier to materials entering of leaving the bloodstream. it normally repels blood cells and platelets so that they flow freely without sticking to the vessel wall.

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5
Q

tunica media

A

the middle layer. is usually the thickets. consists of smooth muscle, collagen, and in some cases, elastic tissue. it strengthens the vessels and prevents blood pressure from rupturing them, and it provides vasomotion, changes in the diameter of a blood vessel.

  • vasoconstriction or vasodilation
  • arteries have thicker tunica media
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6
Q

tunica externa/tunica adventitia

A

outermost layer. it consists of loose connective tissue that often merges with the neighboring blood vessels, nerves, and other organs.

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7
Q

Arteries

A

are sometimes called the resistance vessels of the cardiovascular system because they have a relatively strong, resilient tissue structure that resists high blood pressure.

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8
Q

Conducting (elastic or large) arteries

A

the biggest arteries. The aorta, common carotid and subclavian arteries, pulmonary trunk, and common iliac arteries are examples of conducting arteries.

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9
Q

major systemic arteries

A

supplies oxygen and nutrients to all organs

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10
Q

Ascending aorta

A

rises for about 5cm above the left ventricle. Its only branches are the coronary arteries, which arise behind two cusps of the aortic valve. They are the origins of coronary circulation. Right and left coronary arteries supply the heart.

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11
Q

Aortic arch

A

curves to the left like an inverted U superior to the heart. it gives off three major arteries in this order: the brachiocephalic trunk, left common carotid artery, and left subclavian artery.

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12
Q

brachiocephalic trunk

A
  • right common carotid supplying right side of head

- right subclavian supplying right shoulder and upper limb

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13
Q

left common carotid artery

A

supplying left side of head

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14
Q

left subclavian artery

A

supplying shoulder and upper limb

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15
Q

descending aorta

A

passes downward posterior to the heart, at first to the left of the vertebral column and then anterior to it, through the thoracic and abdominal cavities. It is called the thoracic aorta above the diaphragm and the abdominal aorta below the diaphragm.

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16
Q

common carotid arteries

A

have the most extensive distribution of all the head-neck arteries. Near the laryngeal prominence (Adam’s Apple), each common carotid branches into external and internal carotid artery.

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17
Q

external carotid artery

A

ascends the side of the head external to the cranium and supplies most external head structures

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18
Q

pulmonary circulation

A

pulmonary trunk to pulmonary arteries to lungs. lobal branches for each lobe (3 right, 2 left)

-pulmonary veins return to left atrium. increased O2 and reduced CO2 levels

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19
Q

aneurysm

A

weak point in an artery or the heart wall.

  • forms a thin-walled, bulging sac that pulsates with each heartbeat and may rupture at any time
  • most common sites: abdominal aorta, renal arteries, and arterial circle at the base of the brain
  • can cause pain by putting pressure on other structures
  • can rupture causing hemorrhage
  • result from congenital weakness of the blood vessels or result of trauma or bacterial infections such as syphilis
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20
Q

dissecting aneurysm

A

blood accumulates between the tunics of the artery and separates them, usually because of degeneration of the tunica media

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21
Q

what is the most common cause of aneurysm?

A

the combination of atherosclerosis and hypertension

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22
Q

arterial sense organs

A

sensory structures in the walls of certain vessels that monitor blood pressure and chemistry.
-transmit information to brainstem that serves to regulate heart rate, vasomotion, and respiration

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23
Q

carotid sinuses

A
  • baroreceptors (pressure sensors)
  • in walls of internal carotid artery
  • monitors blood pressure - signaling brainstem
  • decreased heart rate and vessels dilation in response to high blood pressure
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24
Q

carotid bodies

A
  • chemoreceptors
  • oval bodies near branch of common carotids
  • monitor blood chemistry
  • mainly transmit signals to the brainstem respiratory centers
  • adjust respiratory rate to stabilize pH, CO2, and O2
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25
Q

aortic bodies

A

-chemoreceptors
• one to three in walls of aortic arch
• same function as carotid bodies

26
Q

capillaries

A

site where nutrients, wastes, and hormones pass between the blood and tissue fluid through the walls of the vessels (exchange vessels)

  • the ‘business end’ of the cardiovascular system
  • composed of endothelium and basal lamina
  • absent or scarce in tendons, ligaments, epithelia, cornea and lens of the eye
27
Q

capillary exchange

A
  • two way movement of fluid across capillary walls (water, oxygen, glucose, amino acids, lipids, minerals, antibodies, hormones, wastes, cardon dioxide, ammonia)
  • only through capillary walls are exchanges made between the blood and surrounding tissues
  • mechanisms involved: diffusion, transcytosis
28
Q

what is the most important form of capillary exchange?

A

diffusion

-large particles-proteins, held back (aka blood colloid osmotic pressure!)

29
Q

Transcytosis

A
  • endothelial cells pick up material on one side of the plasma membrane by pinocytosis or receptor-mediated endocytosis, transport vesicles across cell, and discharge material on other side by exocytosis
  • important for fatty acids, albumin and some hormones (insulin)
30
Q

Capillary Beds

A
  • capillaries organized into networks called capillary beds (usually supplied by a single metarteriole)
  • thoroughfare channel: metarteriole that continues through capillary bed to venule
  • precapillary sphincters control which beds are well perfused
  • three-fourths of the bodies capillaries are shut down at a given time
31
Q

capillary bed sphincters open

A

-when sphincters open: capillaries are well perfused with blood and engage in exchanges with the tissue fluid

32
Q

capillary bed sphincters closed

A
  • when sphincters closed: blood bypasses the capillaries. flows through thoroughfare channel to venule
  • when the sphincters are closed, little to no blood flow occurs (skeletal muscles at rest)
33
Q

pulmonary capillaries near alveoli

A
  • basketlike capillary beds surround alveoli

- exchange of gases with air and blood at alveoli

34
Q

Capillary Filtration and Reabsorption

A

-think principles behind osmosis and hydrostatic pressure (physical forces exerted by liquids)

  • two forces:
    1. blood hydrostatic pressure drives fluid out of capillary (high on arterial end of capillary, low on venous end)
    2. colloid osmotic pressure (COP) draws fluid into capillary (results from plasma proteins (albumin) - more in blood. oncontic pressure: net COP (blood COP-tissue COP)
  • capillaries reabsorb about 85% of the fluid they filter
  • other 15% is absorbed by the lymphatic system and returned to the blood
35
Q

edema

A

the accumulation of excess fluid in a tissue. occurs when fluid filters into a tissue faster than it is absorbed.

36
Q

three primary causes of edema?

A
  • increased capillary filtration (kidney failure, histamine release, old age, poor venous return)
  • reduced capillary absorption (hypoproteinemia, liver disease, dietary protein deficiency)
  • obstructed lymphatic drainage (surgical removal of lymph nodes)
37
Q

Veins

A

(Capacitance Vessels)

-greater capacity for blood containment than arteries
• thinner walls, flaccid, less muscular and elastic tissue
• collapse when empty, expand easily
• have steady blood flow
• merge to form larger veins
• subjected to relatively low blood pressure
– remains 10 mm Hg with little fluctuation

38
Q

Varicose Veins

A

• Blood pools in the lower legs in people who stand for long periods
– Valves pull apart
– Blood backflows and further distends the vessels
– Hereditary weakness, obesity, and pregnancy also promote problems

39
Q

Superficial Veins of Head and Neck

A
  • internal jugular vein receives most of the blood from the brain
  • branches of external jugular vein drain the external structures of the head
  • upper limb is drained by subclavian vein
40
Q

Great Saphenous Vein

A
  • Longest vein in the body
  • Often times used for surgeries such as coronary bypass
  • Be aware of surgeries in the lower leg!
41
Q

Principles of Blood Flow

A

• Important for delivery of nutrients and oxygen, and removal of metabolic wastes

42
Q

Hemodynamics

A

-physical principles of blood flow based on pressure and resistance
• F is proportional to P/R, (F = flow, P =
difference in pressure, R = resistance to flow)
• the greater the pressure difference between two
points, the greater the flow; the greater the
resistance the less the flow

43
Q

Blood Pressure

A

• 2 pressures are recorded:
1. systolic pressure: peak arterial BP taken during ventricular contraction (ventricular systole)
2. diastolic pressure: minimum arterial BP taken during ventricular relaxation (diastole) between heart beats
• normal value, young adult: 120/75 mm Hg

44
Q

Hypertension

A

• high blood pressure
– chronic is resting BP > 140/90
– consequences
• can weaken small arteries and cause aneurysms

45
Q

Hypotension

A

chronic low resting BP

– caused by blood loss, dehydration, anemia

46
Q

Vasomotion

A

• vasomotion is a quick and powerful way of
altering blood pressure and flow

• three ways of controlling vasomotion:
– local control
– neural control
– hormonal control/chemical

47
Q

autoregulation

A

the ability of tissues to regulate their own blood supply

– metabolic theory of autoregulation – if tissue is inadequately perfused, wastes accumulate stimulating vasodilation which increases perfusion

48
Q

vasoactive chemicals

A

substances secreted by platelets, endothelial cells, and perivascular tissue stimulate vasomotion

– histamine, bradykinin, and prostaglandins stimulate vasodilation (inflammation)

49
Q

reactive hyperemia

A

(gua sha and cupping!)

– if blood supply cut off then restored, flow increases above normal

50
Q

angiogenesis

A

growth of new blood vessels

– occurs in regrowth of uterine lining, around coronary artery obstructions, in
exercised muscle, and malignant tumors

51
Q

Neural Control of Blood Vessels

A

Autonomic nervous systems (and some CNS)

• Vasomotor center of medulla oblongata exerts sympathetic control over blood vessels throughout the body
– stimulates most vessels to constrict, but dilates vessels in skeletal and
cardiac muscle to meet demands of exercise
• precapillary sphincters respond only to local and hormonal control due to lack of innervation

– vasomotor center is the integrating center for three autonomic reflexes
• Baroreflexes-in carotid sinus/regulates BP via medulla
• chemoreflexes-sensitive to pH, O2 and CO2
• medullary ischemic reflex-sens. to insufficient profusion (shock)
• Consider Raynaud’s disease – sympathetic NS, hypoglycemia…

52
Q

Hormonal Control of Blood Pressure: angiotensin II

A

potent vasoconstrictor

– raises blood pressure

53
Q

Hormonal Control of Blood Pressure: aldosterone

A

promotes Na+ and water retention by kidneys

– increases blood volume and pressure

54
Q

Hormonal Control of Blood Pressure: atrial natriuretic peptide

A

increases urinary sodium excretion
– reduces blood volume and promotes vasodilation
– lowers blood pressure

55
Q

Hormonal Control of Blood Pressure: ADH

A

promotes water retention and raises BP

– pathologically high concentrations - vasoconstrictor

56
Q

Hormonal Control of Blood Pressure: epinephrine and norepinephrine effects

A

– most blood vessels
• binds to adrenergic receptors – vasoconstriction (GI)

– skeletal and cardiac muscle blood vessels
• binds to adrenergic receptors - vasodilation

57
Q

Routing of Blood Flow

A

• localized vasoconstriction
– if a specific artery constricts, the pressure
downstream drops, pressure upstream rises
– enables routing blood to different organs as
needed

• examples
– vigorous exercise dilates arteries in lungs, heart
and muscles • vasoconstriction occurs in kidneys and digestive tract
– dozing in armchair after big meal • vasoconstriction in lower limbs raises BP above
the limbs redirecting blood to intestinal arteries

58
Q

Blood Flow in Response to Needs

A

arterioles shift blood flow with changing priorities

59
Q

Mechanisms of Venous Return

A

– Cardiac hydrostatic pressure moves blood
– Skeletal muscle pump in the limbs
• contracting muscle squeezed out of the compressedpart of the vein

– Thoracic (respiratory) pump
• inhalation - thoracic cavity expands and thoracic pressure decreases, abdominal pressure increases forcing blood upward
– central venous pressure fluctuates
• 2mm Hg- inhalation, 6mm Hg-exhalation
• blood flows faster with inhalation

– cardiac suction of expanding atrial space

60
Q

transient ischemic attacks (TIAs )

A

brief episodes of cerebral ischemia

  • caused by spasms of diseased cerebral arteries
  • dizziness, loss of vision, weakness, paralysis, headache or aphasia
  • lasts from a moment to a few hours
  • often early warning of impending stroke
61
Q

stroke

A

cerebral vascular accident (CVA)
– sudden death of brain tissue caused by ischemia
• atherosclerosis, thrombosis, ruptured aneurysm

– effects range from unnoticeable to fatal
• blindness, paralysis, loss of sensation, loss of speech common

– recovery depends on surrounding neurons, collateral circulation

Western Medicine 502 (10 decks)

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