Week 3 Flashcards
(207 cards)
Where do the coronary arteries arise from?
The aorta (at the aortic sinuses) \*branch over surface of heart to supply blood flow to myocardium and epicardium
How does blood from right side of heart come back into the heart?
- Blood from heart returns via small anterior cardiac veins and empty into right atrium
How does blood from left side of heart come back into the heart?
- Blood from heart returns via coronary sinus and empties into right atrium
What is coronary dominance?
Whether a person has a posterior descending artery arising from the RCA or LCA
some people have codominance
Explain how plexus of arteries supply cardiac muscle?
- Coronary arteries lie on surface of the heart
- Smaller arteries then penetrate the cardiac muscle
- There are subendocardial arteries lying beneath the endocardium
- Together they all make a plexus
dWhat are the determinants to regulation of coronary blood flow? (5)
- Aortic pressure (driving force of blood through sinuses)
- Metabolic activity of heart (when heart demands more oxygen during exertion, coronary resistance decreases to allow more blood flow)
- Intraluminal physical forces (When increased intraluminal pressure from arriving from small arteries would cause distention of the large vessels, smooth muscle constriction works to decrease diameter → brings back flow back to original level)
- Extravascular subendocardial arteries experience more pressure due to being squeezed by myocardium or compressed by ventricular filling
- Neural and hormonal factors (sympathetic innervation)
Explain coronary flow reserve
The ratio between maximum coronary flow and resting coronary flow
- The capacity of the coronary circulation to dilate and thus increase flow following an increase in myocardial metabolic demands
What changes can increase resting coronary flow?
- increased resting heart rate
- increased contractility
- This increases resting coronary flow but decreases overall coronary flow reserve
What decreases maximum coronary flow?
- LV hypertrophy
- Microvascular disease
- This decreases both max coronary flow and coronary flow reserve
Less/more coronary flow reserve makes myocardium more vulnerable to ischemia?
- Less coronary flow reserve
Why is subendocardium more vulnerable to ischemia?
Flow in the subendocardium during exertion is impeded by compressive pressure of the systolic contraction and the flow reserve is sooner exhausted leaving tissue vulnerable to oxygen deficits
Explain the coronary steal syndrome?
- occurs downstream of a stenoic or occluded coronary vessel
- At baseline, due to occluded vessel - the downstream vessels will be dilated and lead to an increased resting coronary flow. Although little blood is coming through occluded vessels, other contributing vessels can donate blood to dilated vessels downstream
- When person is given vasodilator therapy, the other contributing vessels and their originating vessels dilate, steal blood that was being “donated”, and lead to the downstream vessels of occluded vessels to go through ischemia
What type of blood is found in pulmonary arteries vs pulmonary veins?
- pulmonary arteries pump deoxygenated blood to lungs
- pulmonary veins bring oxygenated blood back to heart from lungs
What comprises the walls of lymphatic system vessels?
Just endothelium. Highly porous to allow fluids, proteins, cells to cross
What helps lymph fluid move in one direction?
The valves prevent back flow and contraction of muscles during exercise helps push lymph forward
What is the pathway in systemic circulatory system starting with left ventricle?
- Left ventricle
- aorta
- arterial tree
- capillaries
- venous tree
- vena cava
- right atrium
What is the pathway in pulmonary circulatory system starting with right ventricle?
- Right ventricle
- pulmonary arteries
- capillaries of lungs
- pulmonary veins
- left atrium
What is portal blood circulatory system?
Several capillary beds in series
Everything larger than a capillary has vessel walls with 3 layers.
What are the three layers?
- Tunica intima (innermost layer touching blood)
- Tunica media
- Tunica adventitia
What is in the tunica intima?
- endothelium
- basal lamina
- connective tissue
What is in the tunica media?
- smooth muscle cells in circular arrangement
- protein fibers like collagen and/or elastin
What is in Tunica adventitia
- contains connective tissue to attach vessel to body
- the large vessels have blood vessels to supply blood vessels
What are pericytes?
Wrap around capillary cells to offer support and are possible stem cells to create no blood vessels
Aorta/elastic arteries
- size in terms or arteries
- Size of tunica media
- Size of tunica adventitia
- largest of arteries
- Very thick tunica media
- Thinner tunica adventitia
