NSCA CSCS Chapter 1: Structure & Function of Body Systems

Comprehensive practice flashcards covering musculoskeletal, neuromuscular, cardiovascular, respiratory, and acute exercise response concepts from NSCA CSCS Chapter 1.

How many bones are in the adult human skeleton?

206 bones

What structures compose the axial skeleton?

The skull, vertebral column, ribs, and sternum.

What structures compose the appendicular skeleton?

The shoulder girdle and upper limbs, and the pelvic girdle and lower limbs.

What is the structural organization of skeletal muscle from whole muscle down to microstructures?

Whole muscle $\rightarrow$ Fasciculus $\rightarrow$ Muscle fiber $\rightarrow$ Myofibril $\rightarrow$ Myofilaments.

What connective tissue layer surrounds the whole skeletal muscle?

Epimysium

What connective tissue layer surrounds a fasciculus?

Perimysium

What connective tissue layer surrounds each individual muscle fiber?

Endomysium

What are the functions of the sarcolemma, sarcoplasm, and sarcoplasmic reticulum (SR)?

Sarcolemma is the cell membrane of the muscle fiber; sarcoplasm is the cytoplasm of the muscle fiber; sarcoplasmic reticulum (SR) is the specialized structure that stores and releases $\text{Ca}^{2+}$.

What is a sarcomere and how is its boundary defined?

The sarcomere is the smallest contractile unit of a muscle fiber and extends from Z-line to Z-line.

What are the primary contractile and regulatory proteins in skeletal muscle?

Contractile proteins are actin (thin filament) and myosin (thick filament); regulatory proteins are troponin and tropomyosin.

What are the defined regions (A-band, I-band, H-zone, Z-line, M-line) of a sarcomere?

A-band corresponds to the length of thick myosin filaments; I-band contains thin actin filaments without thick-filament overlap; H-zone is the central region containing only thick filaments; Z-line anchors thin filaments at the boundary; M-line is the center of the sarcomere organizing thick filaments.

What happens to the I-band, H-zone, and A-band during sarcomere shortening?

Z-lines move closer; the I-band and H-zone shrink, while the A-band length remains essentially constant.

What is the key sequence of events in the sliding-filament theory of muscular contraction?

$\text{Ca}^{2+}$ binds troponin $\rightarrow$ Tropomyosin moves $\rightarrow$ Myosin binds actin $\rightarrow$ Power stroke $\rightarrow$ ATP permits detachment.

What constitutes a motor unit?

One motor neuron and all the muscle fibers it innervates.

What is the all-or-none principle of motor unit activation?

When a motor neuron fires, all activated fibers within that motor unit contract together.

How does the nervous system grade whole-muscle force production?

Through rate coding (increasing motor-unit firing frequency) and recruitment (activating an increased number of motor units).

What are the major physiological and morphological characteristics of Type I muscle fibers?

Small motor neuron size, low recruitment threshold, slow contraction/relaxation speeds, high fatigue resistance, high aerobic capacity, high capillary and mitochondrial density, high myoglobin content, and small fiber diameter.

What are the major physiological and morphological characteristics of Type IIx muscle fibers?

Large motor neuron size, high recruitment threshold, fast contraction/relaxation speeds, low fatigue resistance, highest force and power output, high anaerobic capacity, large fiber diameter, high anaerobic enzyme content, and low capillary and mitochondrial density.

What sports primarily rely on Type I vs. Type II muscle fiber emphasis?

Type I emphasis: marathon, distance cycling, cross-country skiing/biathlon; Type II emphasis: 100 m sprint, Olympic weightlifting, American football lineman, basketball, volleyball.

How do muscle spindles and Golgi tendon organs (GTOs) differ in location and function?

Muscle spindles are located within skeletal muscle and monitor muscle length and rate of length change to promote contraction; GTOs are located in tendons near the myotendinous junction and monitor tension to reduce tension in the muscle–tendon unit when tension rises.

What is the pathway of blood flow through the heart and cardiovascular circuits?

Body $\rightarrow$ Right heart $\rightarrow$ Lungs $\rightarrow$ Left heart $\rightarrow$ Body.

What is the sequence of electrical conduction through the heart?

SA node $\rightarrow$ AV node $\rightarrow$ AV bundle $\rightarrow$ Bundle branches $\rightarrow$ Purkinje fibers.

What are the standard heart rate thresholds for bradycardia and tachycardia?

Bradycardia is defined as a resting heart rate $<60\,\text{bpm}$, while tachycardia is defined as a resting heart rate $>100\,\text{bpm}$.

What is the primary role of arterioles in blood circulation?

They regulate local blood flow through vasoconstriction and vasodilation.

What is the formula for Cardiac Output?

$$\text{Cardiac Output} = \text{heart rate} \times \text{stroke volume}$$

What is the Fick relationship formula for oxygen uptake ($\text{VO}_2$)?

$$\text{VO}_2 = \text{cardiac output} \times \text{arteriovenous O}_2\text{ difference}$$

How do systolic and diastolic blood pressure respond acutely to sustained aerobic exercise?

Systolic blood pressure rises, whereas diastolic blood pressure generally stays near resting levels or may decrease slightly.

What is reactive hyperemia during high-intensity anaerobic exercise?

The marked increase in muscle blood flow that occurs after a set, following local flow restriction caused by muscle contraction during the set.

What is tidal volume and how does it contribute to minute ventilation during exercise?

Tidal volume is the air moved in one normal breath. At lower to moderate exercise intensities, increases in tidal volume contribute substantially to rising minute ventilation before breathing frequency dominates at higher intensities.