Test 4 Study Guide Part 1 Flashcards
What is the means by which LDL becomes oxidized (in atherosclerosis and inflamatory responses):
Endothelial cells oxidize LDL when they engulf LDL
Oxidized LDL (likely oxidized by endothelial cells) contributes to the inflamatory response in what way? Why does this occur?
Oxidative damage from LDL causes:
Migration of monocytes and lymphocytes into the tunica interna
monocytes -> macrophages.
Other events which progress atherosclerosis.
How effective have antioxidants been in treating atherosclerosis?
What are some common antioxidants?
Not very. Antioxidant drug: probucol Vitamin C Vitamin E Beta-carotene
A drug which is an antioxidant.
Probucol
What is the most common cause of myocardial ischemia (ischemia is poor oxygen supply):
Coronary atherosclerosis.
the build up must restrict blood flow
Myocardial ischemia:
- Causes pain in what two regions:
- What is referred pain?
- Where does it cause it?
- Causes pain in what two regions: Substernal pain Left shoulder and arm - What is referred pain? pain felt in a part of the body other than its actual source. - Where does it cause it? The left shoulder and arm
Nitroglycerin:
- What does it do?
- What can it treat?
- What does it do? A potent vasodilator Like NO - What can it treat? Myocardial ischemia (and other conditions)
Myocardial Infarct:
- Define myocardial infarct:
- Define infarct:
- Define myocardial infarct:
heart attack.
A failure to supply blood to a region of the myocardium - Define infarct:
A small local area of tissue death from failure to supply blood
Why is an infarct particularly nasty for myocardial cells?
Cells of the myocardium are designed to run aerobically. If this fails, then the cells can only run a few minutes on anaerobically and then cell death will occur.
What cells which lie within the area of myocardium infarction?
They will die fairly quickly.
The scar tissue will not be contractile.
In what way can a heart attack be a positive feedback loop.
- Explain “time is muscle”:
Initial death from obstruction of coronary arteries.
The death causes a region which can no longer contract.
This can cause increased ischemia and regions of infarction.
Which can cause more death and the loop continues.
- Explain “time is muscle”:
Meaning the longer before tPA or other factors kick in, the longer the positive feedback loop above will be able to kill more ischemic tissue
Reperfusion injury:
- Cause:
- Effect:
- Cause:
DAMAGE CAUSED BY OXYGEN RETURN, RE- PERFUSION OF TISSUE
Apoptosis due to accumulation of Ca2+ and production of superoxide free radicals (ROS, reactive oxygen species) by mitochondria. - Effect:
cells with these conditions will commit apoptosis
Possible medical reperfusion injury treatments:
- Stem cell therapies:
- Stimulated myocardial cell division:
- Stem cell therapies: from bone marrow (so far no luck) - Stimulated myocardial cell division: (It works in rodent hearts)
What is the number one cause of death in the western world?
Why?
Myocardial infarction
Are diets are garbage, we do not have exercised focus lifestyles, and we live lives of elevated stress (hypertension)
myocardial ischemia is normally accompanied by what?
myocardial infarction is normally accompanied by what?
Depression of the S-T segment.
Elevation of the S-T segment.
Enzymes or components of cell used to measure myocardial infarction:
- Which two are the most sensitive?
- Which is the longest lasting indicator?
Troponin I and T Creatine phosphokinase Lactate Dehydrogenase (high levels in heart because it is used in aerobic respiration) - Which two are the most sensitive? Troponin I and T -Which is the longest lasting indicator? Lactate Dehydrogenase
Two Arrhythmias:
- Bradycardia:
- Tachycardia:
- What is considered the most severe arrhythmia?
- Bradycardia:
< 60 bpm - Tachycardia:
> 100 bpm - What is considered the most severe arrhythmia?
Ventricular tachy cardia (can become ventricular fibrillation)
Atrial Flutter:
- Commonly digresses into:
An irregular circular electrical current in the atria.
- Commonly digresses into:
Atrial Fibrillation. (which will not kill you instantly, as the atria isn’t the most needed)
20 - 25% percent of strokes are estimated to be caused in thrombi from where?
- Caused by what?
- How is it treated?
Atria - Caused by what? Atrial fibrillation - How is it treated? Antithrombic drugs, like warfarin (Coumadin)
Ventricular fibrillation is lethal in minutes, why?
Blood cannot be pumped to other organs, including brain.
Circus Rhythms:
- Define:
- Cause:
- What does this cause?
- Define:
continuous recycling of electrical waves, this is normally avoided by the long refractory phase of myocardial cells - Cause:
Some cells return from their refractory period before others - What does this cause?
V-fib
Uncoordinated an ineffective pumping action
Name two potential causes of circus rhythms:
- Electrocution
- Damage to myocardium (Myocardial infarction)
Asystole:
The cessation of a heart beat.
- Different from v-fib which still has a heart beat. But a v-fib can become an asystole
- V-fib -> asystole common in myocardial ischemia
Electrical Defibrillation:
- How does it work?
- Implantable cardioverter-defibrillator:
- How does it work?
It puts the entire heart into refractory phase.
This allows the sinoatrial node to take control again. - Implantable cardioverter-defibrillator:
defibrillates you if your heart stops for you
Lymphatic system:
- Get’s fluid from:
- Fluid of lymphatic system is called:
- Empties into:
- Get's fluid from: Interstitial fluid all around the body - Fluid of lymphatic system is called: Lymph - Empties into: Sub-mandibular vein
Lymphatic vessels:
- Structure:
- What is present at the capillaries to uptake fluid?
- What propels the lymph?
- Structure:
Exactly like veins. Three layers (tunica: externa, media and intima)
One way valves - What is present at the capillaries to uptake fluid?
Lymph capillaries: blind ended narrow lymphatic vessicles - What propels the lymph?
Skeletal muscle contraction
Peristalsis
Respiratory pump
Where does the lymph travel before rejoining the veins?
To lymph ducts
Lymph nodes:
- What do they do?
- Why are they conc. in the neck and armpits?
- What do they do?
They filter lymph before it is returned, the immune system conc. here - Why are they conc. in the neck and armpits?
Because these are strategic locations where lots of potential contamination can come from
Germinal centers of the lymph nodes:
Found in the center of lymph nodes, act as a site for lymphocyte proliferation.
Lymphoid organs:
- List them:
- Function:
- Can metastasize occur from travel in lymphatic vesicles?
- List them
Spleen, tonsil, and thymus - Function:
Provide large sites for immune processing and proliferation (germinal centers - Can metastasize occur from travel in lymphatic vesicles?
Yes
Cardiac output:
- Measures:
- Cardiac output in a minute:
- Formula:
- Measures: Pumping ability of a single ventricle (which should be the same as the other ventricle - Cardiac output in a minute: ~5.5 liters - Formula: stroke volume (ml/beat) * # beats/minute
What is the blood volume of the average adult?
5.5 liters
Explain the action of the funny current/pacemaker potential:
It opens in response to hyperpolarization and cAMP
K+ and HCN channels are open simultaneously, but Na+ intake predominates.
It helps to ensure constant beating of the heart
What phase changes in length during the depolarization and polarization of pacemaker cells to change the rate a heart beats?
HCN/pacemaker potential/funny current
Effect that changes the rate of the heart.
Chronotropic effect define:
Mechanisms control heart rate:
Parasympathetic innervation of the SA (acetylcholine, opens more K+ channels)
Sympathetic innervation of the SA (norepinephrine/epinephrine, opens HCN channels, increased Na+ flow)
Sympathetic innervation of atrial and ventricular muscles causes stronger contraction, and slightly faster contraction.
What controls the cardiac rate?
Cardiac control center in the medulla oblongata, via feedback by barorecptors and CO2 sensing
Three variables of stroke volume:
End-diastolic volume - Directly proportional Peripheral resistance (afterload) - Indirectly proportional Contractility (the strength of ventricular contraction) - Directly proportional
Frank-Starling law of the heart:
- Law:
- Extrinsic or intrinsic:
- Explain:
- Law:
Increase EDV (stretching) results in increased stroke volume - Extrinsic or intrinsic:
Intrinsic (this occurs even if the heart is beating with no innervation - Explain:
The ideal length of a sarcomere for contraction is ~2.25
Prior to filling with blood during diastole, the sarcomere length is 1.5
The more stretched it is, the better the myosin actin overlap, and the stronger the heart will beat
Ejection fraction:
The percentage of the EDV the heart ejects. It is fairly constant at 60% (due to the Frank-Starling law of the heart)
RyR2 receptors are also increasingly sensitive as the heart is stretched.
- why?
- What does this result in?
- why?
Stretching activates an enzyme, whose end products increase the sensitivity of Ca2+ - What does this result in?
Increased Ca2+ release, which results in a stronger contraction
Anrep effect:
Gradual increase in strength of contraction over the next 10-15 minutes of the heart being stretched.
Results from increased Ca2+ entry from the Na/Ca exchanger
Increased sarcomere length has an increased effect on _____ over _____.
- Which means:
Cardiac
Skeletal muscle
- Which means:
The same length change can cause a much greater increase in contractility in the heart
Venous Return:
- Reason for import:
- Driving force for venous return:
- Reason for import:
heart cannot pump out anything that was not returned to it. - Driving force for venous return:
Venous pressure
Compliance:
- Define:
- Veins vs arteries (and why):
- Define:
The amount of distension they will have in response to pressure - Veins vs arteries:
Veins are much more distension then arteries as they have much thinner walls
Approximately what percentage of blood is within the veins at any point in time?
What name does this lead to veins having?
2/3 of the blood Capacitance vessels (due to ability to hold blood)
Resistance vessels:
Arterioles and muscular arteries, because they expand less under pressure.
Vena cava and the right atrium is the lowest point of blood pressure, what is the blood pressure there?
2 - 6 mm hg
What factors aid in venous return?
- Blood volume
- Sympathetic nerve activity causes vasoconstriction.
- Skeletal muscle pump
- Respiratory pump
