A & P 101-Cardiovascular System


A & P 101-Cardiovascular System


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Anatomy & Physiology 101- The Cardiovascular System

The Human Body is without a doubt the most complex organism on this planet. It is absolutely fascinating how are bodies are designed and what they are capable of. To better explore our bodies I have decided to write a weekly blog about a different body part or system. Some may be very in depth, some may be in more “caveman terms” depending its usefulness of deeper knowledge. The first topic of choice is our cardiovascular system. The cardiovascular is comprised of the heart and two different networks of blood vessels; pulmonary circulation and systemic circulation.


First I need to cover the anatomy of the heart.

Your heart has four chambers. Blood enters the heart through the superior & inferior vena cava and empties into the right atrium. From there, de-oxygenated blood passes the tricuspid valve and into the right ventricle. during contraction, the blood is the pushed beyond the semi-lunar valve and into the Pulmonary arteries. This carry de-oxygenated blood to the lungs, where oxygen will be added to the blood. Then the oxygenated blood will travel down the pulmonary veins (only veins in your entire body to hold oxygenated blood) and into the left atrium. The blood then passes the mitral valve and into the left ventricle where during contraction it is pushed out of the aorta and into your body.


Your heart has some pretty unusual characteristics that sets it apart from the other muscles in your body.


this “spontaneous depolarization” means that your heart can actually beat on its own. The cardiac cells can contract on their own. Your Brain doesn’t need to tell your heart to beat, your heart just knows.


In order to properly function, the cardiac cells must be able to conduct electricity. Origination in the upper right quadrant of your heart in the Sinoatrial Node (SA node) the cardiac cells conduct or pass the electricity in a wave like pattern to to every area of the heart. As they pass the electricity and depolarize, the blood in your heart is able to travel from top atrium’s into the ventricles, or from the ventricles into the pulmonary artery or out the aorta and into your systemic circulation.


Simply Put, your heart has the ability to exert force through contraction.


due to the property of automaticity we know that the heart cell’s can produce their own signal, but for organization and proper contractions to occur the pacemaker, SA Node, controls the rate at which the heart will beat. The other cells in the body must be able to respond to a stimulus with minimal difficulty. As the SA node receives signals to either speed up, or slow down to meet the demands of the body, the other cells of the heart must be able to act accordingly.


 Systemic Circulation

Okay so we have two major highways here. Arteries and Veins. Arteries carry oxygenated blood away from the heart, whereas veins bring de-oxygenated blood back to the heart. As blood leaves the heart it travels through the Aorta. This is the largest artery in the body. It travels from the base of the heart to about your belly button at which point is splits into the femoral arteries. there is a section of the aorta called the “aortic arch” where three main arteries send blood to each arm and your brain.

So whichever road you take, you will eventually end up into smaller streets, then residential areas and finally one lane streets and alleys. This is basically how your systemic circulation works. Your Aorta branches off into arteries and eventually into arterioles. these are the back alleyways in your cardiovascular system. This is also where oxygen is “off-loaded” from the blood and into your muscles. Just one street over, those arterioles now turn into venules. these venules are the smallest veins in your body. they pick up the de-oxygenated blood and start the journey back home to the heart.

Capillary bed

This whole off-loading and on-loading area is called your capillary beds. Venules eventually follow the same pattern turning into veins and finally the Inferior & Superior Vena Cava. Which leads us directly back to the heart!! so easy, and amazing.


So we have The pump covered, The pipes have been discussed, now what about the oil?!?! Your entire cardiovascular system was designed for one thing. Get oxygen & nutrients to the muscles. The transporter (no its not Jason Stathom) is your blood. Blood is comprised of some different things that are worth talking about here.

Red Cells (erythrocytes)

formed in bone marrow and an alarming rate of 2-3 million per second, Red blood cells are comprised of almost entirely hemoglobin. Hemoglobin is what the oxygen molecules will attach to in the lungs and eventually off-load at the muscles. Red blood cells are unique in that they life for 120 days then go to the spleen to die. so every four months your body will have entirely new red blood cells.

White Cells (leukocytes)

White Cells make up a very small percentage of your blood-1% in a normal person. These cells are not limited to just the blood stream, they are also found in other organs such as liver, spleen and the lymph glands. While there are also many different types of White cells, their main purpose is to be our immune response. They look for, flag, alert, and destroy any bacteria or virus that has contaminated our bodies.

Platelets (thrombocytes)

Platelets are responsible for our clotting capabilities. These are the guys that keep our bathrooms not looking like Texas chain saw massacre when we get cut shaving, or in the kitchen while cooking.

erythrocyte (left), thrombocyte
(center), and leukocyte (right)


Plasma makes up about 55% percent of our blood. it is relatively clear and mostly made up of water. Plasma is what all the components that make up our blood travels in.

There you have it. A short semi-detailed overview of our cardiovascular system. I hope it wasn’t too much of an overload, and I hope you got some good things out of it. Also take a look at these cool site about the heart as well as this video on the cardiovascular system.

36 interesting facts about the heart

cardiovascular system video

Workout of the Day: 3 October 12

A) 6x 2 Snatch Balance + 2 OH Squat

*rest 45 sec*

*work up to heaviest while maintaining good technique*

B) 2 min AMRAP:

Ground-To-Overhead (135/95)

Then immediately,

5 Rounds:

5 Box Jumps (34″/26″)


10 GHD Situps