NASM Chapter 3 (CardioRespiratory)

Hey there!

Right now, in this moment there is something happening to you.

You should be glad that it is happening to you.

It’s something you shouldn’t have to think about.

It’s something that is keeping you alive.

It’s your heart.

It’s your heart’s four chambers working in perfect synchronization.

Alright that’s enough. I am being melodramatic.

The Cardio-Respiratory system.

This really is a combination of two linked body systems.

The linked systems are:

1. Cardiovascular- The Heart, Blood, Blood Vessels

2. Pulmonary/Respiratory- The airway(Upper: Nasal Cavity, Pharynx, Larynx. Lower: Trachea, Primary Bronchi) Lungs, and Respiratory muscles (Diaphragm, Intercostal muscles)

Let’s start with the strongest muscle you’ve got.

The Heart.

Located almost dead center in your chest, behind your sternum, and in front of your spine. It has four chambers. Made up of Cardiac Muscle Cells, and typically can not be consciously controlled.

See how the Cardiac Muscle Cells link together? That’s for efficiency, and maintaining it’s own electrical current.

So there’s approximately 60,000 miles of blood vessels in the human body. The heart is strong enough to cover ever inch of that 60,000 miles with blood flow.

How does it do that? You ask.

By the structure of it’s cells. Remember how above we saw that the Cardiac Muscle Cells are linked together? This allows the heart to:

• Hold together- During the contraction, and contract as one.
• Generate Electrical Current- It creates it’s own action potential.

Have you ever pumped up a bicycle tire? Yes, you know how hard it is to get to 100 pounds of pressure per square inch? Pretty labor intensive right? Well your heart adds twenty more pounds of pressure in an instant. This is the called the Systolic Pressure. Which is when the Left Ventricle contracts and shoots blood to the rest of the body. Now think back to pumping up that bike tire. Normal resting heart rate is 70–80 beats per minute. Which means your heart is pumping up a tire to 120 pounds of pressure every second, while you are resting.

Holy smokes! That’s IMPRESSIVE. Am I right?

All that pumping takes a lot of effort, how does it do it so rhythmically?

Good question!

Here’s how. The heart has specialized cells that carry an electrical signal from the Sinoatrial Node (SA) through the both atria and down to the ventricles.

The Sinoatrial Node (SA)- Is the Pace Maker of the heart. Think of your heart as a great big orchestra. All the different valves, veins, arteries, and muscles are the musicians. The Sinoatrial Node is the maestro/conductor of that orchestra.

Lub dub. Lub dub. That’s the sound of the heart beat. Notice how it has two parts? Well the Lub is the atria filling with blood then pushing that blood to ventricles. The DUB is the ventricles contracting and getting the blood to where it needs to go.

Why did I bring that up? Because there are four chambers of the heart, and they need to follow that contraction pattern or death might occur. How does it do that. By a coordination of the Sinoatrial Node (SA)and the Atrioventricular Node(AV).

The Atrioventricular Node (AV) delays the impulse from the Sinoatrial Node (SA) then onto the ventricles.

Uh guess I should clarify that the Sinoatrial Node is located on the RIGHT ATRIUM. While the Atrioventricular Node is located on the FLOOR of RIGHT ATRIUM

Now that we got some visuals lets talk about the structure of the heart. It is composed of Four Hollow Chambers.

1. Right Atrium
2. Right Ventricle

The right side of the heart is known as the PULMONIC Side, because it receives deoxygenated blood from the body. Meaning the blood is low in Oxygen content, and high in Carbon Dioxide content. So Right side=CO2 > 02. It then takes the blood it receives and pushes it to the lungs then back to the heart where it enters the left side. This side also has thinner walls, because it has a short distance to pump.

3. Left Atrium

4. Left Ventricle

The left side of the heart is known as the Systemic Side. Because it pumps blood to the rest of the body/system. The blood has returned from the lungs and it recharged with oxygen. So Left Side= 02>CO2. This side has thicker walls, because it has to pump to the whole body.

Each chamber has a valve(s) to prevent back flow. These valves are subdivided into two groups.

1. The Atrioventricular Valves- Which are Tricuspid and the Mitral

2. The Semilunar Valves- Which are the Pulmonary and the Aortic

Can you find the Atrioventricular Valves?

We now see that the heart is incredibly strong. So what? Big deal! I can move liquid around too. Where’s my parade!

You are right. We need to visualize how much fluid the heart actually pushes through that 60,000 miles of blood vessels.

Lets figure that out.

Stroke Volume: is the amount of blood pumped out with each Contraction. It is the difference between the Ventricular End Diastolic Volume (EDV) and the End Systolic Volume (ESV).

• Ventricular Diastolic Volume (EDV)- The filled volume of the ventricle before contraction.
• Ventricular End Systolic Volume- The Residual Volume of blood remaining in the Ventricle after ejection.

So a typical heart the EDV=120ML’s fill the ventricle.

ESV=50ML’s are left in the ventricle after ejection.

So Stroke Volume of a typical heart is EDV(120)- ESV(50)= 70ML’s per stroke.

Then you multiple the Stroke volume by your heart rate. Which is How many times your heart beats in a minute. A typical resting heart rate is 70–80 beats per minute.

To get Cardiac Output.(Q)

So Stroke Volume multiplied by Heart Rate= Cardiac Output

SV x HR=Q

in a typical heart.

SV70 x HR70= Q4,900 Ml’s per minute. Divide that by a thousand to get it into liters. and it is 4.9 liters per minute. 4.9 multiplied by 60=294 liters per hour. then multiply that by 24= 7,056 liters per day! And that’s if you were resting the entire day. WHOA.

Unfortunately, there isn’t a simple way to measure Stroke Volume. But we can measure heart rate.

We do this by counting the Pulse in 15 seconds and multiplying it by 4. Thus we know someone’s Heart Rate. Or you know you could just buy a measuring device and figure it out that way.

We still got a little more to cover, to wrap up the cardio vascular side of the Cardiorespiratory System.

But Imma save that for tomorrow.

If you have any questions, or criticism go ahead and let me know via a comment.

Thanks for reading.

and remember Live Creatively

Work Passionately

See things in New Perspectives.