Chapter 3: Skeletal Muscle System

• Card 1

  • Front: What are the primary components of muscle composition?

  • Back: Muscles are primarily made up of:

    • Water (65-75%)

    • Protein (20%)

    • Other components like lipids, carbohydrates, electrolytes, ATP, and phosphocreatine (PCr) (5%) [1]

• Card 2

  • Front: What is the function of muscle fibers?

  • Back: Muscle fibers, the long, parallel cells in skeletal muscles, produce force when they are stimulated, which allows movement. This happens because chemical energy from ATP is converted into mechanical energy. [2]

• Card 3

  • Front: What are the different types of connective tissues in muscles and their functions?

  • Back:

    • Tendons: Connect muscles to bones. [3]

    • Epimysium: Covers the whole muscle. [3]

    • Perimysium: Covers bundles of muscle fibers (fasciculi). [3]

    • Endomysium: Covers each individual muscle fiber. [3]

• Card 4

  • Front: What is a sarcomere and what happens to it during muscle contraction?

  • Back: The sarcomere is the basic unit of contraction in a muscle. It has protein filaments called actin and myosin arranged in a specific way that gives skeletal muscle its striped look. [4] When a muscle contracts, the sarcomere gets shorter as the actin filaments slide over the myosin filaments. This makes the H zone disappear and the I bands shorten. [4]

• Card 5

  • Front: What are the main types of muscle fibers?

  • Back:

    • Type I (slow-twitch): Good for endurance activities because they are fatigue-resistant and have a high capacity for oxidative metabolism. [5]

    • Type II (fast-twitch): Good for short bursts of high-intensity activity because they can produce force quickly but tire easily and have a low capacity for oxidative metabolism. [6]

• Card 6

  • Front: Explain the sliding filament theory.

  • Back: This theory describes how muscle proteins work together to create force. Actin and myosin filaments slide past each other, but they don't change length. [7] The force generated depends on how many actomyosin complexes are formed. [7] This sliding is powered by ATP through a process called cross-bridge cycling. [8, 9]

• Card 7

  • Front: Define proprioception.

  • Back: Proprioception is the body's ability to sense where it is in space. This is done by special receptors called proprioceptors, which are found in muscles and tendons. They send signals to the brain about muscle length and force. [10, 11]

• Card 8

  • Front: What factors influence the amount of force a muscle can produce?

  • Back: Several factors impact how much force a muscle can produce:

    • The cross-sectional area of the muscle [12]

    • Muscle length [12]

    • Neural influences [12]

• Card 9

  • Front: Describe the length-tension relationship in muscles.

  • Back: The length-tension relationship means that a muscle produces its maximum force at a specific length. This is where there's the best overlap between the actin and myosin filaments. [13]

• Card 10

  • Front: What adaptations occur in muscles due to resistance training?

  • Back: When you start resistance training, strength gains happen first because of neural changes, like better motor unit recruitment. [14] Later, gains mostly come from muscle hypertrophy, which is when muscle fibers get bigger. [15]

Chapter 4: The Nervous System

• Card 11

  • Front: What are the key functions of the nervous system?

  • Back: The nervous system has several vital roles:

    • Starting Movements: It sends signals from the brain to the muscles to make them contract and move. [13]

    • Maintaining Homeostasis: It regulates different body processes to keep the internal environment stable. [14]

• Card 12

  • Front: Describe the organization of the nervous system.

  • Back: The nervous system is organized into two main parts: [15-17]

    • Central Nervous System (CNS): This includes the brain and spinal cord. [16]

    • Peripheral Nervous System (PNS): This consists of all the nerves connecting the CNS to the rest of the body. [17]

• Card 13

  • Front: What are the divisions of the peripheral nervous system (PNS) and their functions?

  • Back: The PNS is further divided into: [18, 19]

    • Somatic Nervous System: This controls voluntary movements. [18]

    • Autonomic Nervous System: This regulates involuntary functions like heart rate, blood pressure, digestion, and breathing. [19]

• Card 14

  • Front: What are the branches of the autonomic nervous system and their roles?

  • Back: The autonomic nervous system has two branches: [20, 21]

    • Sympathetic Nervous System: This is activated in "fight-or-flight" situations. [20]

    • Parasympathetic Nervous System: This promotes "rest and digest" functions. [21]

• Card 15

  • Front: What are the main components of a neuron and their functions?

  • Back: Neurons are special cells that send information through electrical impulses. Here are their key parts: [22-25]

    • Dendrites: They receive impulses from other neurons. [23]

    • Cell Body: This contains the nucleus and other important cell structures. [24]

    • Axon: This carries the impulse away from the cell body. [25]

• Card 16

  • Front: How are impulses conducted along neurons?

  • Back: Impulses travel along neurons as electrical signals called action potentials. Myelination affects the speed of conduction. Myelinated nerves conduct impulses faster through a process called saltatory conduction. [21, 22, 26]

• Card 17

  • Front: What is a synapse and how does it function?

  • Back: A synapse is the junction between two neurons where communication takes place. Neurotransmitters, which are chemical messengers, are released from the presynaptic neuron and bind to receptors on the postsynaptic neuron, transmitting the signal. [22, 23, 27]

• Card 18

  • Front: Explain the neuromuscular junction.

  • Back: The neuromuscular junction is a special synapse where a motor neuron connects to a muscle fiber. Acetylcholine is released into the synaptic cleft, causing the muscle to contract. [28]

• Card 19

  • Front: What is a motor unit and how does it operate?

  • Back: A motor unit is a motor neuron and all the muscle fibers it controls. When a motor unit is stimulated, all the fibers in it contract together. This is called the all-or-none principle. [25, 26, 29]

• Card 20

  • Front: Describe the size principle of motor unit recruitment.

  • Back: Motor units are recruited in order of their size. This means smaller, slow-twitch units are activated first, followed by larger, fast-twitch units. [27, 30]

• Card 21

  • Front: What are the neural adaptations that occur in response to exercise?

  • Back: Training leads to adaptations in the nervous system that improve performance. These include increased motor unit recruitment and firing rate, as well as better coordination and timing of muscle contractions. [31]

Chapter 5: Cardiovascular System

• Card 22

  • Front: What are the main components of the cardiovascular system?

  • Back: The key components of the cardiovascular system are: [29, 32]

    • Heart: This muscular pump circulates blood throughout the body. [33]

    • Blood: The fluid that transports oxygen, nutrients, and waste products. [34]

    • Blood Vessels: The arteries, veins, and capillaries make up the circulatory system. [35]

• Card 23

  • Front: Differentiate between pulmonary and peripheral circulation.

  • Back: [29, 36, 37]

    • Pulmonary Circulation: Blood flow between the heart and lungs, where gas exchange occurs. [38]

    • Peripheral Circulation: Blood flow between the heart and the rest of the body. [37]

• Card 24

  • Front: Describe the structure of the heart.

  • Back: The heart is a four-chambered organ with two atria (upper chambers) and two ventricles (lower chambers). Valves between the chambers ensure blood flows in one direction. [30] The left ventricle has a thicker wall than the right ventricle because it pumps blood to the whole body against higher resistance. [31]

• Card 25

  • Front: Explain the phases of the cardiac cycle.

  • Back: The cardiac cycle has two main phases: [39-41]

    • Systole: The contraction phase, when the heart pumps blood out. [40]

    • Diastole: The relaxation phase, when the heart fills with blood. [41]

• Card 26

  • Front: What are the mechanisms of heart rate control?

  • Back: Heart rate is controlled by two mechanisms: [32-34, 42-44]

    • Intrinsic Control: This is the heart's own electrical conduction system, which starts in the sinoatrial (SA) node, known as the natural pacemaker. [32, 43]

    • Extrinsic Control: Regulation by the nervous system and hormones. The sympathetic nervous system increases heart rate (tachycardia), and the parasympathetic nervous system decreases heart rate (bradycardia). [44]

• Card 27

  • Front: Define cardiac output and how it's calculated.

  • Back: Cardiac output (Q) is the volume of blood the heart pumps per minute. It's calculated as: Q = heart rate (HR) x stroke volume (SV). [35, 45]

• Card 28

  • Front: What is stroke volume and what factors influence it?

  • Back: Stroke volume (SV) is the amount of blood ejected from the ventricle with each heartbeat. [35, 46] It's influenced by: [36, 38, 47, 48]

    • End-Diastolic Volume (EDV): The volume of blood in the ventricle at the end of diastole. [47]

    • End-Systolic Volume (ESV): The volume of blood left in the ventricle after systole. [48]

• Card 29

  • Front: What factors contribute to venous return?

  • Back: Venous return, the blood flow back to the heart from the veins, is essential for maintaining cardiac output. It's helped by: [37, 49-52]

    • Venoconstriction: Narrowing of the veins to increase pressure and blood flow. [50]

    • Muscle Pump: Skeletal muscle contractions squeeze blood through the veins toward the heart. [51]

    • Respiratory Pump: Pressure changes in the chest during breathing assist venous return. [52]

• Card 30

  • Front: Explain the Frank-Starling Mechanism.

  • Back: The Frank-Starling Mechanism describes how the heart adjusts its stroke volume based on venous return and end-diastolic volume. Increased filling stretches the ventricle, leading to a more forceful contraction and greater stroke volume. [53, 54]

• Card 31

  • Front: What are the components of blood?

  • Back: Blood consists of: [40, 55, 56]

    • Plasma: The liquid component of blood.

    • Formed Elements: This includes red blood cells, white blood cells, and platelets.

• Card 32

  • Front: Describe the redistribution of blood flow during exercise.

  • Back: During exercise, blood flow is redirected away from organs that aren't essential at that moment and toward the working muscles. [42, 57] This is controlled by: [43, 58, 59]

    • Vasodilation: Widening of blood vessels in the active muscles. [58]

    • Vasoconstriction: Narrowing of blood vessels in inactive tissues. [59]

• Card 33

  • Front: What is blood pressure and what influences it?

  • Back: Blood pressure is the force blood exerts on the walls of blood vessels. [44, 60] It's affected by cardiac output and total peripheral resistance (TPR). [45]

• Card 34

  • Front: Differentiate between systolic and diastolic blood pressure.

  • Back: [46, 60]

    • Systolic Blood Pressure: The highest pressure when the ventricles contract.

    • Diastolic Blood Pressure: The lowest pressure when the ventricles relax.

• Card 35

  • Front: What factors determine oxygen delivery to tissues?

  • Back: Oxygen delivery depends on cardiac output and the arteriovenous oxygen difference (a-v O2 diff). [47, 48, 61] The a-v O2 diff represents how much oxygen is taken from the blood by the tissues. [48]