Exam 3 - Blood Vessels, Atherosclerosis, Cardiac Arrhythmias, and Lymphatic System Flashcards
(58 cards)
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)
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
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)
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
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
6
Q
how blood passes from the arterioles to venules directly
A
arteriovenous anastomoses
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)
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
9
Q
walls of capillaries
A
- composed of one cell layer – a simple squamous epithelium, or endothelium
- allows more rapid exchange
10
Q
types of capillaries
A
- continuous
- fenestrated
- discontinuous
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)
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)
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)
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
15
Q
where is most of the total blood volume contained?
A
venous system (veins are able to expand as they accumulate blood)
16
Q
average pressure in veins vs average arterial pressure
A
- average pressure in veins = 2 mmHg
- average arterial pressure = 100 mmHg
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
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
19
Q
what things produce the “insults” to the endothelium that likely cause atherosclerosis?
A
- smoking
- hypertension
- high blood cholesterol
- diabetes
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
21
Q
intermediate stage of atherosclerosis
A
- layers of macrophages and smooth muscle cells
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
23
Q
the disease process of atherosclerosis
A
- paracrine regulators are secreted by the endothelium, platelets, macrophages, and lymphocytes
24
Q
endothelin-1
A
- paracrine regulator
- vasoconstrictor effects
- increased in atherosclerosis
25
ways *endothelial cells* prevent **atherosclerosis** progression
* 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
***familial hypercholesteremia***
* 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
LDLs
* **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
VLDLs
* **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
**apolipoproteins**
* 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
apolipoprotein B
* 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
why do people who eat a diet high in cholesterol and saturated fat, and people with familial hypercholesteremia have a high blood LDL concentration?
* **their livers have a low number of LDL receptors**
32
HDLs
* **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
*C-reactive protein*
* marker of inflammation
* a stronger predictor of atherosclerotic heart disease than the blood LDL cholesterol level
34
drugs that may help treat **atherosclerosis** or prevent it
* antioxidants:
* ***probucol***
* ***vitamin C***
* ***vitamin E***
* ***beta-carotene***
35
most common cause of **myocardial ischemia**
* 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
ischemia
when a tissue's oxygen supply is deficient because of inadequate blood flow (perfusion)
37
angina pectoris
* myocardial ischemia is associated with _increased concentrations of blood lactic acid_
* causes _substernal pain_ (*referred pain* to left shoulder and arm)
38
nitroglycerin
* durg that people with *angina pectoris* take to help relieve _ischemia_ and pain
* _produces vasodilation_
39
necrosis
cell death
40
myocardial infarction
* 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
reperfusion injury
* 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
potential therapies for myocardial infarction
* 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
detecting a myocardial ischemia and myocardial infarction on an ECG
* 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
diagnosis of MI
* 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
athlete's bradycardia
* result of higher levels of *parasympathetic inhibition of SA node*
* beneficial adaptation
46
causes of abnormal tachycardia
* 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
flutter vs. fibrillation
* 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
atrial fibrillation
* 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
ways to treat atrial fibrillation
* 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
circus rhythms
continuous recycling of electrical waves through the myocardium that causes fibrillation
51
mechanisms that cause the chaotic electrical activity that cause fibrillation
* ***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
electrical defibrillation
* 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
extracellular matrix
* consists of:
* collagen proteins
* gel formed of _glycosaminoglycans_
54
lymphatic system 3 basic functions
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
lymph ducts
* 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
lymphatic system flow (add picture)
* 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
lymph nodes
* filter lymph before it returns to cardiovascular system
* contains _phagocytic cells_ and **germinal centers** (sites of new lymphocyte production)
58
lymphoid organs
* tonsils
* thymus
* spleen
* contain germinal genters
