Untitled Flashcards Set

Study Guide for Muscles Quiz

1. Muscle Contraction Mechanism

• Sliding Filament Model:

  • Actin (thin filament) slides over myosin (thick filament) during muscle contraction.

  • The length of the muscle changes as the myofilaments slide past each other, but the length of each filament itself does not change.

  • During contraction, the Z lines in the sarcomere move closer together as the sarcomere shortens.

2. Muscle Fiber Types

• Slow-Twitch Fibers:

  • Primarily used in aerobic activities (e.g., long-distance running).

  • Contain high levels of myoglobin and many mitochondria to produce energy efficiently with oxygen.

• Fast-Twitch Fibers:

  • Used in anaerobic activities (e.g., sprinting), relying on short bursts of strength and speed.

  • Produce energy without oxygen and fatigue faster.

3. Muscle Anatomy and Structure

• Hierarchy of Muscle Structure (largest to smallest):

  • Muscle fibers → myofibrils → myofilaments.

  • Myosin (thick filaments) and actin (thin filaments) are organized in sarcomeres within myofibrils.

• Sarcomere:

  • The structural unit of a muscle fiber, composed of myosin and actin filaments.

  • Myosin (thick) filaments remain stationary, while actin (thin) filaments slide to cause contraction.

4. Muscle Contraction Physiology

• Myogram Phases:

  • Latent Period: Delay between stimulation and the start of contraction.

  • Contraction Phase: Muscle fibers shorten and generate force.

  • Relaxation Phase: Muscle fibers return to resting length.

• Summation and Tetanus:

  • Summation: Occurs when muscle fibers do not completely relax between stimuli, increasing the contraction strength.

  • Tetanus: Continuous contraction when stimuli are frequent enough, preventing relaxation.

5. Functions of Skeletal Muscles

• Movement: Enables movement by contracting and pulling on bones.

• Posture: Maintains body posture against gravity.

• Heat Production: Generates heat as a byproduct of contraction.

• Protection: Provides padding for bones and internal organs.

6. Muscle Pairs and Movements

• Antagonistic Pairs: Muscles that work in opposition (e.g., biceps and triceps). One contracts while the other relaxes.

• Synergistic Pairs: Muscles that work together to produce a similar movement.

7. Muscle Contraction Biochemistry

• Key Molecules:

  • Calcium Ions (Ca²⁺): Released from the sarcoplasmic reticulum, binds to troponin, causing tropomyosin to move and exposing binding sites on actin.

  • ATP: Provides energy for the myosin heads to bind to actin, pull, release, and reattach in a "power stroke" during contraction.

• Sequence of Contraction Events:

1. Nerve signal triggers release of Ca²⁺.

2. Ca²⁺ binds to troponin, causing a shape change that shifts tropomyosin, exposing myosin-binding sites on actin.

3. Myosin heads attach to actin, pull, detach, and repeat, powered by ATP.

8. Important Structures in Muscle Contraction

• Tropomyosin: Blocks myosin binding sites on actin when the muscle is at rest.

• Troponin: Binds with calcium ions, which allows tropomyosin to move and exposes the binding sites on actin.

• Myosin Heads: Attach to actin filaments and pull them toward the center of the sarcomere during contraction.

9. Steps in Muscle Contraction (Sliding Filament Theory)

• Initiation:

  • Calcium ions bind to troponin.

  • Tropomyosin moves away from binding sites on actin.

• Contraction Cycle:

1. Attachment: Myosin heads bind to actin.

2. Power Stroke: Myosin heads pivot, pulling actin toward the center.

3. Detachment: ATP binds to myosin, causing it to release actin.

4. Reactivation: ATP is hydrolyzed, re-cocking the myosin head for the next cycle.

10. Recognizing Muscle Roles

• Flexor vs. Extensor Muscles:

  • Flexors: Muscles that bend a joint (e.g., biceps).

  • Extensors: Muscles that straighten a joint (e.g., triceps).

Key Terms to Remember

• Actin & Myosin: Protein filaments responsible for muscle contraction.

• Sarcoplasmic Reticulum: Organelle that releases calcium ions in response to a nerve signal.

• Sarcomere: The functional unit of muscle fibers.

• Antagonistic Muscles: Muscle pairs that work in opposition, such as biceps (flexor) and triceps (extensor).

Focus on understanding the sliding filament model of contraction, muscle fiber types, and the roles of calcium ions and ATP in muscle contraction. Knowing the sequence of events in muscle contraction and relaxation will help with both multiple-choice and matching questions. Good luck studying!

Study Guide for Lungs Quiz

1. Inhalation and Exhalation

• Inhalation:

  • Air enters the lungs because atmospheric pressure is greater than the pressure inside the lungs.

  • The diaphragm contracts, moving downward, and the intercostal muscles contract, causing the chest cavity to expand and lung volume to increase.

  • This decrease in pressure allows air to flow into the lungs.

• Exhalation:

  • The diaphragm and intercostal muscles relax, causing the chest cavity and lung volume to decrease.

  • The pressure inside the lungs becomes greater than atmospheric pressure, forcing air out of the lungs.

2. Lung Anatomy and Function

• Key Structures:

  • Bronchi: Carry air into the right and left lungs.

  • Bronchioles: Smaller tubes that carry air into the alveoli within each lung.

  • Alveoli: Tiny air sacs where gas exchange occurs; provide a large surface area for oxygen and carbon dioxide exchange.

  • Pleural Membranes: Attach the lungs to the chest cavity and help the lungs expand and contract with the thoracic cavity.

• Airflow Pathway:

  • Air travels through the respiratory system in the following order:
    Pharynx → Larynx → Trachea → Bronchi → Bronchioles → Alveoli

3. Gas Exchange

• Mechanism:

  • Gas exchange is a passive process caused by differences in partial pressure.

  • Oxygen diffuses from the alveoli (high oxygen concentration) into the blood (low oxygen concentration).

  • Carbon dioxide diffuses from the blood (high CO₂ concentration) into the alveoli (low CO₂ concentration).

• High Altitude Pulmonary Edema (HAPE):

  • Caused by fluid build-up in the alveoli, which reduces the efficiency of gas exchange.

  • Symptoms: Shortness of breath, fatigue, chest tightness, and frothy fluid production.

  • Common at high altitudes due to reduced oxygen availability and pressure.

4. Breathing Regulation

• Role of CO₂ and pH:

  • Carbon dioxide is converted to carbonic acid in the blood, which affects blood pH.

  • The brain monitors blood pH (not oxygen levels directly) and adjusts breathing rate to maintain proper CO₂ and pH levels.

• Events During Exercise:

  • CO₂ levels in the blood increase → Medulla oblongata sends nerve impulses to breathing muscles → Depth and frequency of breathing increase → Gas exchange in the lungs increases → CO₂ levels return to normal.

5. Mechanics of Breathing

• Key Processes:

  • Inhalation: Diaphragm and intercostal muscles contract → Thoracic cavity volume increases → Pressure decreases → Air flows into the lungs.

  • Exhalation: Diaphragm and intercostal muscles relax → Thoracic cavity volume decreases → Pressure increases → Air flows out of the lungs.

• Events During Inhalation:

  • Volume of thoracic cavity increases.

  • Pressure inside the thoracic cavity decreases.

  • Diaphragm and intercostal muscles contract.

  • Air flows into the lungs.

6. Respiratory Terminology

• External Respiration: Gas exchange between alveoli and blood.

• Internal Respiration: Gas exchange between blood and body tissues.

• Tidal Volume: The amount of air inhaled or exhaled in a normal breath.

7. Structures and Their Functions

• Trachea: The "windpipe" that allows air to travel to the bronchi.

• Larynx: The "voicebox," involved in sound production.

• Diaphragm: Dome-shaped muscle that separates the thoracic and abdominal cavities; its contraction aids inhalation.

• Intercostal Muscles: Muscles between the ribs that help expand and contract the chest cavity.

• Surfactant: A fluid that reduces surface tension in the alveoli, preventing them from sticking together and collapsing.

8. Key Points for Gas Exchange

• Oxygen and CO₂ Transport:

  • Oxygen binds to hemoglobin in red blood cells for transport.

  • CO₂ is mostly transported as bicarbonate ions in the blood.

• Factors Affecting Gas Exchange:

  • Surface area of the alveoli.

  • Partial pressure differences of oxygen and carbon dioxide.

  • Health conditions such as HAPE or lung diseases.

Key Equations

1. Partial Pressure of Oxygen and CO₂:
   Gas moves from areas of higher partial pressure to lower partial pressure.

Study Tips

1. Focus on understanding the mechanics of breathing (diaphragm and intercostal muscles).

2. Review the pathway of air through the respiratory system.

3. Understand how CO₂ levels and blood pH regulate breathing.

4. Learn the effects of high altitude on gas exchange and how the body compensates.

5. Familiarize yourself with the structure and function of alveoli for efficient gas exchange.

Good luck!