And so it (thankfully!) flows – our Blood Vascular System

For the first 13 or so Human Anatomy lectures by Marian C. Diamond, I was an enthralled and eager student. Since the session on Cardiology, and continuing on with the last two lectures on our Blood Vascular System, I have remained enthralled and eager, but another adjective has been added to that list: tingled. Not quite squeamish, just tingled. Bones and muscles fascinate me because I enjoy being active and am curious about what I “see” – my skin covers my muscles and bones, but I can visualize those body components easily and imagine how they are impacted by my various physical activities – walking, yoga, swimming and kayaking.

For all intents and purposes, my muscles and bones are not continual moving parts. They move when I tell them to move. On the other hand, the blood coursing through my body, my heart continually moving to pump that blood – these are the “moving” parts of my body that function regardless of whether I “tell” them to move or not. Thank goodness for that, yet it is their very “movability” that tingles my learning about this process. Okay, I am still enthusiastic, but my stomach tingles when reading about blood!

Systemic Circulation

Our blood takes a distinct path through our bodies. Arteries take blood away from our heart, beginning with the Aorta exiting from the left ventricle, then funneling into arterioles followed by capillaries, with each type of vessel being smaller than the previous type. The capillaries, though the smallest of the arteries, have multiple microscopic branches feeding into our tissues. These arterial vessels transport freshly oxygenated blood, bringing nutrients and gases to our body, and picking up wastes.

As blood courses through our bodies it eventually returns to our heart via the Veins, beginning with the small venules that funnel into the larger veins. As it heads to the heart, blood from the lower extremities collects in the inferior vena cava while blood from the upper extremities (except for the heart) collects in the superior vena cava. Inferior and superior refer to location below and above the diaphragm.

Gravity helps our arteries do their job, but on the return trip the veins get some help from our skeletal muscles. To prevent blood from flowing backwards, our veins have valves that open to let blood pass and then close to prevent backflow.

Pulmonary Circulation

As our veins return blood to the heart, the blood needs to be cleansed of waste products, such as carbon dioxide, and pick up more oxygen before it can be pumped through the heart to exit back to our body via the arteries. This cleansing and refreshing of our blood happens in our lungs.

Blood reenters the heart via the right atrium and is then pumped to the lungs by the right ventricle. After circulating through our lungs, the blood returns to the heart via the left atrium where it is pumped to the left ventricle to start the process all over again.

Tweets & Lectures 16 & 17

@brainbits: M.Diamond–Blood Vascular System lec: 1/3 US deaths due to heart attacks, so we should know how to care for our hearts

@brainbits: Bone & muscle have relatively few moving parts (except for when we purposely move them) compared to our heart and blood vascular system.

@brainbits: Factors impacting blood pressure:age, sex, weight, race, mood, physical activity, posture & socioeconomic status. ch 19

@brainbits: Benefits of exercise on cardiovascular sys–heart increases in size&strength, heart rate goes down+stroke volume rises–result in next tweet!

@brainbits: Ongoing exercise–>lower heart rate = Heart relaxes more, beats less + HDL blood levels improves & LDL levels reduced.

@brainbits: Our muscular & cardiovascular systems have mutually beneficial relationship nourished by regular exercise. It’s summer, decouch &get moving!

@brainbits: Marian Diamond suggests keep your bodies strong & healthy so as you age, if you fall, you can protect your head from hitting the ground.

@brainbits: M.Diamond’s UC Berkeley Human Anatomy lec 17 – Our blood vascular system is complex & beautifully organized.

@brainbits: And on blood’s return to the heart, the longest vein is the Saphenous, which runs from the arch of your foot all the way up to your thigh.

@brainbits: The Aorta–largest artery from which all other arteries stem. Just imagine, where it exits your heart it’s approx the size of a garden hose!

@brainbits: Systemic Circulation sends the freshly oxygenated blood throughout our body, transporting nutrients, gases and wastes.

@brainbits: Pulmonary Circulation sends deoxygenated, high CO2 blood coursing from our heart to our lungs to pick up oxygen & drop off carbon dioxide.


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