CSCS Study Guide Chapter 1: Structure and Function of Body Systems

Edited by: Danielle Abel

Essentials of Strength & Conditioning: Chapter 1

Chapter 1 of the NSCA CSCS textbook is about laying the foundation of anatomy and physiology as it relates to strength & conditioning. 

Some key points you'll want to focus on include:

• Skeletal system
• Muscular system & physiology
• Sliding filament theory
• Muscle fiber types & function
• Cardiovascular system 
• Respiratory system

You'll need to know that there are 2 portions of the skeletal system

• Axial skeleton (skull, ribcage, vertebra)
  • the vertebral column consists of:
    • 7 cervical vertebra
    • 12 thoracic vertebra
    • 5 lumbar vertebra
    • and the sacrum/coccyx
• Appendicular skeleton (everything else - scapula, humerus, pelvis, femur, etc.)

We also have joints that connect bone to bone, from a strength and conditioning perspective, you'll need to know that the synovial joints (shoulder, hip, knee, & elbow) are the joints primarily involved in movement. Synovial joints include 2 parts, the joint capsule, where synovial fluid is located, and bone ends, where hyaline & articular cartilage is found. 

The muscular system consists of muscles, tendons, & ligaments

You might have only thought about the muscles when considering the muscular system, but we also need to include the 2 connective tissue structures that facilitate muscular function: tendons & ligaments. 

• Tendons attach muscle to bone
• Ligaments attach bone to bone

Muscles themselves 6 different layers from the outer most layer to the inner most layer:

• Muscle belly 
• Fascicle 
• Muscle fiber
• Myofibril
• Sarcomere
• Actin/myosin

Another area of the muscular system includes the fascia, which is a thin connective tissue that surrounds each muscle and muscular structure.

There are 3 different types of fascia that you'll need to know

Fascia is like a covering on different portions of the muscle and muscle components. Each one has an associated prefix that helps you to know where it's located:

• Epi = outermost
• Peri = middle
• Endo = innermost

The epimysium sounds the outermost, layer of muscle, or the muscle belly. The perimysium surrounds the fascicles or groups of muscle fibers and the endomysium surrounds one muscle fiber. 

Fascicles, Motor Units, & Muscle Fiber 

Fascicles are simply groups of muscle fibers that are located together. They're grouped together by their fiber type (Type I, Type II, etc.). A motor unit is simply a fascicle that is controlled by 1 nerve. By being controlled by 1 nerve, the fibers in one unit contract at the same time. Keep in mind that since fiber types are of different sizes, motor units may also be different sizes. 

Muscle fibers are simply muscle cells.

Inside of each myofibril is a sarcomere. Sarcomeres are the contractile units of muscles and are composed of actin & myosin. Sarcomere's contain the following structural components that you'll need to know:

• Z Discs (the walls of the structure)
• A Band (the length of the myosin - this section never changes size)
• I Band (contains actin but no myosin)
• H Zone (contains myosin but no action

The I Band and the H Zone shorten when a muscle contracts. 

Sliding Filament Theory & Action Potential

The sliding filament theory says that muscle contracts because myosin and action interact with one another, forming cross bridges, that produce movement.

This action happens at the very smallest level of the muscle fiber (inside the sarcomere). 

Action potentials are what initiate the muscle to contract. Action potentials are sent from the brain down nerves to the neuromuscular junction via neurotransmitters:

• Causes acetylcholine (Ach) to be released
• Acetylcholine crosses the neuromuscular junction
• The signal then goes down the T-tubules
• This causes calcium to be released in the sarcoplasmic reticulum
• Next, troponin binds to tropomyosin and pulls tropomyosin out of the way
• Tropomyosin moves out of the way, which opens the myosin binding site
• Myosin binds to action forming a cross bridge
• Muscle contraction occurs

Keep in mind that the rate at which the signal (action potential) is sent down the nerve is referred to as rate coding, which can be trained. 

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Muscle Fiber Types, Muscle Spindles, Golgi Tendon Organ

There are 3 different types of skeletal muscle fibers that you will need to know for the CSCS exam:

• Type I Oxidative Fibers (aerobic training)
• Type IIa: Mixed Fibers
• Type IIx: Glycolytic (1-5 Rep Max)

You'll need to know that muscle spindles sense muscle stretch. For example, the anterior shoulder (the anterior deltoid muscle) is stretched during the layback of a pitch. This results in a reflexive contraction to slow the arm down & keep it from overstretching. 

Muscle spindles sense a muscle stretch and cause muscle contraction to occur. 

Golgi Tendon Organs are quite literally the opposite of muscle spindles, golgi tendon organs tell the muscle to relax or lengthen by sensing a muscle contraction. For example, the achilles tendon is stretched when you're sprinting and therefore causes an inhibition to the calf muscles. 

Blood Flow Through Cardiovascular System

You'll need to know both the structures that blood flows through in the heart and also how blood gets to the muscles. 

Blood flow through the heart starts on the right side of the heart, goes to the lungs, and then comes back into the left side of the heart. The blood always flows from the top (atrium) down to the bottom (ventricles).

• Vena Cava
• Right Atrium 
• Tricuspid Valve
• Right Ventricle Pulmonary Artery

Lungs, then

• Pulmonary Vein
• Left Atrium 
• Mitral Valve
• Left Ventricle
• Aorta

Out to the body (and muscles).

From the aorta the blood flows to the arteries to the veins via the following pathways:

• Arteries 
• Arterioles
• Capillaries
• Venules
• Veins

Conduction Signals Through the Heart

The electrical conduction signal always initiates at the sinoatrial node (SA). From the SA node, the signal travels down to the atrioventricular node (AV) where the impulse is delayed. From the AV node the signal travels down the AV bundles (also known as the Bundle of His) and then down into the Purkinje Fibers. 

Keep in mind that knowing the typical resting heart rate is essential too. A resting heart rate of between 60-100 beats per minute is considered normal, whereas anything below 60 is considered slow and is referred to as bradycardia. Anything above 100 is considered fast and is referred to as tachycardia. 

Electrocardiogram Readings

When looking at an electrocardiogram (ECG) you will see a number of distinct waves. You will need to know what is happening at the level of the heart in each wave. 

• P Wave (the atria depolarizes here)
• QRS Complex (the ventricles depolarize & the atria repolarize
• T Wave (the ventricles repolarize here)

Respiratory System Structure & Function

The lungs are the main player when it comes to respiration in the body. Through our lungs, we inspire oxygen and expire carbon dioxide. From the lungs, oxygen moves to the alveoli where gas exchange occurs via the following route:

• Lungs
• Trachea
• Bronchi
• Bronchiole
• Alveoli

Keep in mind that the right lung has 3 lobes, and the left lung has 2 lobes so that we have room for our heart. You should also know that oxygenated blood travels from the body's arteries and back to the pulmonary vein, whereas deoxygenated blood is carried by the veins and is returned to the pulmonary artery.  

Support & Courses Available

Ready for more support to help you prep for the CSCS exam? Join our Facebook Group, “Strength and Conditioning Study Group,” here. Ready for even more? Our 24-module CSCS Prep Course has Structure & Function of Body Systems completely laid out for you with even more content than what we’ve provided here, plus chapter quizzes to help you pass the NSCA exam; click the link here to check it out.