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Advanced Human Physiology > Exam 3 - Blood Vessels, Atherosclerosis, Cardiac Arrhythmias, and Lymphatic System > Flashcards

Exam 3 - Blood Vessels, Atherosclerosis, Cardiac Arrhythmias, and Lymphatic System Flashcards

1
Q

coats that make up walls of arteries and veins

A
  • tunica externa
    • outermost layer
    • composed of connective tissue
  • tunica media
    • middle layer
    • composed of smooth muscle
  • tunica interna (intima)
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2
Q

three parts of the tunica interna

A
  • innermost simple squamous epithelium, the endothelium
    • lines the lumina of all blood vessels
  • the basement membrane (a layer of glycoproteins)
    • overlying some connective tissue layers
  • a layer of elastic fibers, or elastin, forming an internal elastic lamina
    • this part is not found in capillaries
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3
Q

arteries vs veins

A
  • arteries
    • more muscle
    • appear more rounded
    • no valves
  • veins
    • partially collapsed
    • have one-way valves (because blood flow is slower)
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4
Q

elastic arteries

A
  • largest arteries (i.e. aorta)
  • many layers of elastin fibers between the smooth muscle cells of the tunica media
  • elastic recoil drives the blood during the diastolic phase
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5
Q

muscular arteries

A
  • small arterioles and arteries
  • less elastic
  • thicker layer of smooth muscle than elastic arteries
  • provide the greatest resistance to blood flow through arterial system
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6
Q

how blood passes from the arterioles to venules directly

A

arteriovenous anastomoses

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7
Q

gap junctions between the cells of the arteriole wall

A
  • in both the endothelial and smooth muscle layers
  • propagates the vasoconstrictor effect of norepinephrine (depolarization) and the vasodilator effect of acetylcholine (hyperpolarization)
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8
Q

what does the amount of blood flowing through a capillary bed depend on?

A
  • depends primarily on the resistance of blood flow in the small arteries and arterioles
  • blood flow may also be regulated by circular muscle bands called precapillary sphincters
    • in organs such as the intestine
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9
Q

walls of capillaries

A
  • composed of one cell layer – a simple squamous epithelium, or endothelium
    • allows more rapid exchange
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10
Q

types of capillaries

A
  • continuous
  • fenestrated
  • discontinuous
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11
Q

continuous capillaries

A
  • capillaries in which adjacent endothelial cells are closely joined together
  • found in muscles, lungs, adipose tissue, CNS
    • lack of intercellular channels in CNS contributes to the blood-brain barrier
    • other organs have narrow intercellular channels that permit passage of molecules other than protein
  • pinocytotic vesicles
    • intracellular transport of material may occur across the capillary walls
    • only mechanism of capillary exchange available with the CNS (may account for selectivity of blood-brain barrier)
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12
Q

fenestrated capillaries

A
  • found in kidneys, endocrine glands, intestines
  • characterized by wide intercellular pores that are covered by a layer of mucoprotein
    • serves as a basement membrane over the capillary endothelium
    • mucoprotein layer restricts the passage of certain molecules (such as proteins)
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13
Q

discontinuous capillaries

A
  • found in liver, spleen, bone marrow
  • distance between endothelial cells is so great that they capillaries look like little cavities (sinusoids)
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14
Q

two things that stimulate capillary growth

A
  • vascular endothelial growth factor (VEGF)
    • when a tissue is hypoxic
  • adenosine (derived from AMP)
    • also stimulates vasodilation of arterioles and thereby increased blood flow to the hypoxic tissue
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15
Q

where is most of the total blood volume contained?

A

venous system (veins are able to expand as they accumulate blood)

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16
Q

average pressure in veins vs average arterial pressure

A
  • average pressure in veins = 2 mmHg
  • average arterial pressure = 100 mmHg
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17
Q

three mechanisms for venous return to the heart

A
  • venous valves
    • as veins are squeezed by contracting skeletal muscles, a one-way flow of blood to the heart is ensured by the present of venous valves
  • skeletal muscle pump
    • massaging action of skeletal muscles on venous blood flow
    • rate is dependent on action of these pumps
    • aids return of venous blood from lower limbs to large abdominal veins
  • respiratory pump
    • movement of venous blood from abdominal to thoracic veins
    • inhalation causes diaphragm to contract, increasing the pressure in the abdomen and decreasing the pressure in the thoracic cavity
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18
Q

Atherosclerosis

A
  • most common form of arteriosclerosis (hardening of arteries)
  • localized plaques (atheromas) protrude into the lumen of the artery and reduce blood flow
    • these atheromas also serve as sites for thrombus formation
  • inflammatory disease
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19
Q

what things produce the “insults” to the endothelium that likely cause atherosclerosis?

A
  • smoking
  • hypertension
  • high blood cholesterol
  • diabetes
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20
Q

first anatomically recognized change in atherosclerosis?

A
  • appearance of fatty streaks
    • these are gray-white areas that protrude into the lumen of arteries
    • aggregations of lipid-filled macrophages and lymphocytes within the tunica intima
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21
Q

intermediate stage of atherosclerosis

A
  • layers of macrophages and smooth muscle cells
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22
Q

fibrous plaques

A
  • more advanced lesions of atherosclerosis
  • consist of:
    • a cap of connective tissue with smooth muscle cells over lipid and debris
    • macrophages (derived from monocytes)
    • lymphocytes
  • becomes thin and prone to rupture, resulting in a thrombus
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23
Q

the disease process of atherosclerosis

A
  • paracrine regulators are secreted by the endothelium, platelets, macrophages, and lymphocytes
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24
Q

endothelin-1

A
  • paracrine regulator
  • vasoconstrictor effects
  • increased in atherosclerosis
25
Q

ways endothelial cells prevent atherosclerosis progression

A
  • present a physical barrier to the penetration of monocytes and lymphocytes
  • produce paracrine regulators such as nitric oxide
    • vasodilator action helps to counter vasoconstrictor effects of endothelin-1
26
Q

familial hypercholesteremia

A
  • inherited condition
    • single dominant gene
  • causes high blood cholesterol that can lead to atherosclerosis
    • if two genes are inherited, the person usually suffers heart attacks during childhood
27
Q

LDLs

A
  • low-density lipoproteins
    • plasma proteins that carry cholesterol to the arteries
    • derived from very low-density lipoproteins (VLDLs)
  • gets turned into oxidized LDL when it is engulfed by endothelial cells
28
Q

VLDLs

A
  • very low-density lipoproteins
    • produced by liver
    • composed of cholesterol, triglycerides, free fatty acids, and phospholipids
      • become LDLs when most of the triglycerides are removed
29
Q

apolipoproteins

A
  • proteins in low-density lipoproteins
  • bind to receptors
    • cell then engulfs the LDL particles by receptor-mediated endocytosis
      • this is how most LDL particles are removed by the liver
30
Q

apolipoprotein B

A
  • uptake of this particular LDL prtoein into the subendothelial connective tissue of an artery is believed to initiate the formation of an atherosclerotic plaque
    • promotes entry of monocytes –> conversion to macrophages –> foam cells
31
Q

why do people who eat a diet high in cholesterol and saturated fat, and people with familial hypercholesteremia have a high blood LDL concentration?

A
  • their livers have a low number of LDL receptors
32
Q

HDLs

A
  • high-density lipoproteins
    • carry cholesterol away from arterial wall
    • protects against atherosclerosis by accepting cholesterol from foam cells and carrying it through the blood to the liver for metabolism
  • HDL levels are largely determine by genetics
    • some people have a genetic insufficiency in the cell receptors for HDL
33
Q

C-reactive protein

A
  • marker of inflammation
    • a stronger predictor of atherosclerotic heart disease than the blood LDL cholesterol level
34
Q

drugs that may help treat atherosclerosis or prevent it

A
  • antioxidants:
    • probucol
    • vitamin C
    • vitamin E
    • beta-carotene
35
Q

most common cause of myocardial ischemia

A
  • atherosclerosis of coronary arteries
  • mental stress can also cause constriction of atherosclerotic coronary arteries, leading to ischemia (this is believed to result from abnormal function of a damaged endothelium)
36
Q

ischemia

A

when a tissue’s oxygen supply is deficient because of inadequate blood flow (perfusion)

37
Q

angina pectoris

A
  • myocardial ischemia is associated with increased concentrations of blood lactic acid
    • causes substernal pain (referred pain to left shoulder and arm)
38
Q

nitroglycerin

A
  • durg that people with angina pectoris take to help relieve ischemia and pain
    • produces vasodilation
39
Q

necrosis

A

cell death

40
Q

myocardial infarction

A
  • sudden, irreversible injury that occurs when ischemia and anaerobic metabolism are prolonged
  • “heart attack”
  • leading cause of death in Western world
  • fibroblasts produce noncontractile scar tissue
41
Q

reperfusion injury

A
  • when the heart becomes re-perfused with blood after MI
    • larger numbers of myocardial cells die; this is caused by:
      • apoptosis due to the accumulation of Ca2+ and the production of superoxide free radicals
42
Q

potential therapies for myocardial infarction

A
  • potential stem cell therapies
    • stem cells from bone marrow (secrete cytokines)
    • differentiation of embryonic stem cells and induced pluripotent stem cells into myocardial cells
    • transformation of fibroblasts into myocardial cells
  • stimulate myocardial cell division
43
Q

detecting a myocardial ischemia and myocardial infarction on an ECG

A
  • a myocardial infarction is accompanied by an elevation of the S-T segment
  • myocardial ischemia is accompanied by an elevation, or depression of the S-T segment
44
Q

diagnosis of MI

A
  • main way to diagnose: rising blood troponin levels, primarily troponin I
  • tests for enzymes released into blood by damaged myocardial cells:
    • creatine phosphokinase (CPK)
    • lactate dehydrogenase (LDH)
45
Q

athlete’s bradycardia

A
  • result of higher levels of parasympathetic inhibition of SA node
  • beneficial adaptation
46
Q

causes of abnormal tachycardia

A
  • abnormally fast pacing by the atria (caused by drugs)
    • abnormal atrial tachycardia (differs from normal, or sinus tachycardia)
  • development of abnormally fast ectopic pacemakers
    • ​ventricular tachycardia
    • causes ventricles to beat rapidly and independently of the atria
    • this can lead to ventricular fibrillation
47
Q

flutter vs. fibrillation

A
  • extremely rapid rates of electrical excitation and contraction of either the atria or ventricles may produce a flutter or fibrillation
  • flutter - contractions are very rapid (200-200/min) but are coordinated
  • fibrillation - contractions of different groups of myocardial cells occur at different times, so that a coordinated pumping action of the chambers is impossible
48
Q

atrial fibrillation

A
  • contraction of atria is ineffectual
  • only reduces cardiac output by about 15%
  • associated with increased mortality due to stroke and heart failure
    • 20-25% of all strokes result from thrombi promoted by atrial fibrillation
  • the most common heart arrhythmia
49
Q

ways to treat atrial fibrillation

A
  • antithrombotic drugs
  • antiarrhythmia drugs
  • percutaneous catheter ablation
    • procedure that destroys the atrial tissue around the pulmonary veins (the usual source of the abnormal electrical activity)
50
Q

circus rhythms

A

continuous recycling of electrical waves through the myocardium that causes fibrillation

51
Q

mechanisms that cause the chaotic electrical activity that cause fibrillation

A
  • focal excitation
    • a region of the myocardium outside the SA node that is damaged spontaneously depolarizes
  • reentry
    • an action potential can be continuously regenerated and conducted along a pathway (i.e. a scar) that is not in the refractory phase
  • delivery of an external electric shock at the middle of the T wave when different myocardial cells are in different stages of recovery from their refractory period
52
Q

electrical defibrillation

A
  • electric shock that depolarizes all of the myocardial cells at the same time, causing them all to enter a refractory state
    • conduction of circus rhythms stops
    • SA node can begin to stimulate contraction in a normal fashion
  • implantable converter-defibrillator available to high-risk patients
53
Q

extracellular matrix

A
  • consists of:
    • collagen proteins
    • gel formed of glycosaminoglycans
54
Q

lymphatic system 3 basic functions

A
  1. transports interstitial (tissue) fluid back to the blood
  2. transports absorbed fat from the small intestine to the blood
  3. lymphocytes provide immunological defenses against pathogens
55
Q

lymph ducts

A
  • walls are similar to those of veins
    • same 3 layers
    • contain valves
  • fluid movement occurs as a result of:
    • peristalsis (smooth muscle)
      • the smooth muscle within the lymph ducts contains a pacemaker that initiates action potentials associated with entry of Ca; activity is increased in response to stretch of vessel
    • valves
    • compression during contraction of skeletal muscle and arterial pulsation
56
Q

lymphatic system flow (add picture)

A
  • once fluid enters lymphatic capillaries, it is referred to as lymph
    • lymphatic capillaries are composed of endothelial cells with porous junctions
  • lymphatic system may also transport cancer cells
57
Q

lymph nodes

A
  • filter lymph before it returns to cardiovascular system
  • contains phagocytic cells and germinal centers (sites of new lymphocyte production)
58
Q

lymphoid organs

A
  • tonsils
  • thymus
  • spleen
  • contain germinal genters

Advanced Human Physiology (10 decks)

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