1 Flashcards
What is the skeletal system?
A system of bony levers that provide support and protection.
How many bones are in the body?
Approximately 206.
What are the two divisions of the skeleton?
Axial and appendicular.
What bones are part of the axial skeleton?
Vertebral column, coccyx, ribs, and sternum.
What bones are part of the appendicular skeleton?
Shoulder/pectoral girdle, arms, wrists and hands, pelvic girdle, legs and ankles, and feet.
What bones make up the vertebral column?
Cervical, thoracic, lumbar, and sacral vertebrae.
What is the function of the vertebral column?
Provides support and allows movement.
How many cervical vertebrae are there?
Seven (C1-C7).
How many thoracic vertebrae are there?
Twelve (T1-T12).
How many lumbar vertebrae are there?
Five (L1-L5).
What are the five sacral vertebrae?
Fused together and make up the rear of the pelvis.
What factors affect skeletal growth in adults?
Muscle use
How can skeletal bone density be increased?
Heavy loading, explosive movements, frequency of loading axial skeleton
What is required for effective long-term skeletal adaptations?
Varied frequency, intensity, and type of stimulus
Do bones adapt faster than muscles?
No, bones take more time to adapt than muscles
What are joints?
Junctions of bones in the skeleton.
What are the three types of joints?
Fibrous, cartilaginous, and synovial.
What covers the articulating ends of bones?
Smooth hyaline cartilage.
What is the joint capsule filled with?
Synovial fluid.
What are the additional supporting structures of joints?
Ligaments and cartilage.
What type of movement do fibrous joints allow?
Virtually no movement.
What type of movement do cartilaginous joints allow?
Limited movement.
What type of movement do synovial joints allow?
Considerable movement.
What is an example of a fibrous joint?
Sutures of the skull.
What is an example of a cartilaginous joint?
Intervertebral discs.
What is an example of a synovial joint?
Elbow and knee.
What are the characteristics of synovial joints?
Low friction, large range of motion, most movements occur about them.
What are the three categories of articulating joints?
Uniaxial, biaxial, multiaxial
What is an example of a uniaxial joint?
Elbows and knees
What is an example of a multiaxial joint?
Shoulder and hip ball-and-socket joints
What are the categories for muscle attachments?
Location-based
How are limb muscle attachments categorized?
Relative to midline
How are trunk muscle attachments categorized?
Relative to head position
What is a proximal attachment?
Limb muscle closer to midline
What is a distal attachment?
Limb muscle further from midline
What is a superior attachment?
Trunk muscle closer to head
What is an inferior attachment?
Trunk muscle closer to feet
What are skeletal muscles composed of?
Muscle tissue, connective tissue, nerves, and blood vessels.
What are tendons?
Fibrous connective tissue that attaches muscles to bone periosteum.
What is epimysium?
Outer connective tissue layer surrounding the muscle.
What are fasciculi?
Bundles of muscle fibers.
What is perimysium?
Middle connective tissue surrounding fasciculi.
What is endomysium?
Inner connective tissue that surrounds each muscle fiber.
What is sarcolemma?
Muscle fiber membrane contiguous with endomysium.
What is the diameter of muscle fibers?
About 50-100 micrometers.
What is the function of tendons?
To transmit tension developed in the muscle to the tendons and bone attachments.
What is the function of epimysium?
To cover every muscle in the human body.
What is the function of perimysium?
To surround fasciculi.
What is the function of endomysium?
To surround each muscle fiber.
What is the function of muscle fibers?
To group into bundles known as fasciculi.
What are muscles composed of?
Muscle fibers
What is the diameter of muscle fibers?
50-100 micrometers
What are the contractile components in muscle fibers?
Floating proteins
What are muscle fibers grouped into?
Fasciculi
What is the sarcolemma?
Muscle fiber membrane
What are myofibrils composed of?
Actin and myosin
What is the smallest contractile unit in a muscle?
Sarcomere
What forms crossbridges in myofibrils?
Pairs of myosin filaments
What regulates muscle contraction?
Calcium ions in sarcoplasmic reticulum
What are T-tubules?
Intricate system of tubules
Where do T-tubules terminate?
Near the Z-line between two sarcomeres
What delivers the signal from the motor neuron to all depths of the muscle fiber?
T-tubules
What is a sarcomere?
The smallest contractile unit in a muscle.
How are sarcomeres organized?
Based on areas containing myosin or actin.
What does the A-band correspond to?
Alignment of myosin filaments.
What does the I-band correspond to?
Area between two adjacent sarcomeres containing only actin.
What does the Z-line do?
Runs perpendicular to the I-band, separating each sarcomere.
What is the H-zone?
The center of sarcomeres that contains only myosin filaments.
What are motor units?
Motor neurons and muscle fibers they innervate
What are motor neurons?
Nerve cells responsible for innervating muscle fibers
What is the neuromuscular junction?
Junction between muscle fiber and motor neuron
How many neurons are responsible for innervating each muscle fiber?
Only one
How many muscle fibers can a single motor neuron innervate?
Hundreds or thousands
What is the ‘all-or-nothing principle’?
All fibers in a motor unit contract simultaneously
What are the components of a motor unit?
Motor neuron, neuromuscular junction, muscle fibers
What is the sliding filament theory?
Theory of muscle contraction
What are the five phases of the sliding filament theory?
Resting, Excitation-contraction coupling, Contraction, Recharge, Relaxation
What happens during the resting phase?
Calcium stored in sarcoplasmic reticulum, few myosin crossbridges bound to actin
What happens during the excitation-contraction coupling phase?
Nervous system signals motor unit to contract, calcium released from sarcoplasmic reticulum, binds with troponin, H-zone and I-band shrink, Z-lines pull together
What happens during the contraction phase?
ATP on myosin crossbridge breaks down via hydrolysis, energy for pulling action delivered by breakdown of ATP into ADP and phosphate, known as power stroke
What happens during the recharge phase?
New ATP replaces ADP on myosin crossbridge, contractions repeat if calcium, ATP, and ATPase available
What is the enzyme that catalyzes the breakdown of ATP during the contraction phase?
Myosin ATPase
What is the power stroke?
Pulling action during muscle contraction
What happens during the relaxation phase?
Calcium is pumped back into sarcoplasmic reticulum, myosin crossbridges detach from actin, muscle returns to resting state
What is the role of troponin in muscle contraction?
Binds with calcium to initiate muscle contraction
What are the two categories of muscle fibers?
Fast twitch and slow twitch.
What is a motor unit?
Fibers of the same type.
What are slow-twitch fibers known as?
Type I fibers.
What are fast-twitch fibers known as?
Type II fibers.
What are the two types of fast-twitch fibers?
Type IIa and Type IIx.
What are the characteristics of Type I fibers?
Efficient, resistant to fatigue, high capillary density, high density of mitochondria, high capacity for using aerobic energy, low recruitment threshold.
What is the recruitment threshold of Type I fibers?
Lower than required for Type II fiber activation.
What is the potential for rapid force development and anaerobic power in Type I fibers?
Limited.
What is the endurance and fatigue resistance capacity of Type I fibers compared to Type IIa and Type IIx?
Greater.
What are the characteristics of Type II fibers?
Inefficient, rapidly fatigue, capable of rapidly producing force for short periods of time, significant anaerobic power.
What is the difference between Type IIa and Type IIx fibers?
Type IIa fibers have a greater capacity for aerobic metabolism and more capillaries than Type IIx making them more resistant to fatigue.
What are postural muscles?
Muscles with large composition of Type I fibers needed for endurance throughout the day. Example: Soleus.
What are prime mover muscles?
Muscles that include Type I and Type II fibers due to varying needs. The intensity of the activity will determine the relative involvement of fiber types. Example: Quadriceps group.
What are the two ways muscle force is graded?
Frequency of motor unit activation and increase in total number of activated motor units.
What happens when twitch frequency increases?
Muscular force increases.
What is tetanus?
A state of muscle activation where twitches merge together.
What are the adaptations to resistance training that improve force production?
Increased twitch frequency and increased numbers of activated motor units.
How can muscle force production in athletes be improved?
Incorporating phases of training with heavier loads, increasing muscle cross-section area, and focusing on explosive, multi-muscle, multi-joint exercises.
What are muscle spindles and Golgi tendon organs?
Specialized sensory receptors for proprioception
What information do proprioceptors provide?
Position of body parts with respect to gravity
How is proprioceptive information processed?
Subconsciously
What is the function of muscle spindles?
Provide information on muscle length and rate of change
What happens when muscle spindles are stretched?
Cause corresponding muscle fibers to contract
What is the function of Golgi tendon organs?
Provide information on muscle tension
Where are Golgi tendon organs located?
In tendons near myotendinous junction
What happens when the tendon attached to an active muscle is stretched?
Golgi tendon organs activate
What is the response of Golgi tendon organs to increased muscle tension?
Discharge increases and inhibits muscle tension
What is the function of inhibitory neurons stimulated by GTO discharge?
Reduce tension in the muscle
What is the possible function of GTO response?
Protect against excessive muscle tension
Can motor cortex signals override GTO response?
Yes
What is the overall effect of muscle spindle activation?
Increases activation in respective motor unit
What is the overall effect of GTO activation?
Decreases activation in respective motor unit
What is the function of intrafusal fibers?
Modified muscle fibers enclosed in a sheath of connective tissue
What is the function of extrafusal fibers?
Normal muscle fibers that run parallel to intrafusal fibers
What is the heart?
A muscular organ with two pumps
What is the function of the right side of the heart?
Pumps blood through lungs for oxygenation
What is the function of the left side of the heart?
Pumps oxygenated blood throughout the body
What are the chambers of the heart?
Right atrium, right ventricle, left atrium, left ventricle
What is the function of the right atrium?
Receives non-oxygenated blood from the body
What is the function of the right ventricle?
Pumps blood through the pulmonary circulation
What is the function of the left atrium?
Receives oxygenated blood from pulmonary circulation
What is the function of the left ventricle?
Pumps oxygenated blood through the body
What is the function of the tricuspid and mitral valves?
Prevent backflow of blood from ventricles into atria during systole
What is the function of the aortic and pulmonary valves?
Prevent blood flow from aorta and pulmonary arteries during diastole
What is the sinoatrial node?
Pacemaker of the heart, source of rhythmic electrical impulses
What is the atrioventricular node?
Delays impulse from the SA node to allow blood into the ventricles
What is the atrioventricular bundle?
Conducts impulse to ventricles via the left and right bundle branches
What are Purkinje fibers?
Further branching of the left and right bundle branches
What controls the rhythm of the heart muscles?
Medulla in the brain
What are the two nervous systems that transmit signals to the heart?
Sympathetic and parasympathetic
What effect does the sympathetic nervous system have on heart rate?
Increases heart rate
What effect does the parasympathetic nervous system have on heart rate?
Decreases heart rate
What is the typical resting heart rate range?
60 BPM to 100 BPM
What is bradycardia?
Heart rate fewer than 60 BPM
What is tachycardia?
Heart rate over 100 BPM
What is an ECG?
A graphical representation of heart’s electrical activity.
What are the components of a normal ECG?
P-wave, QRS complex, T-wave.
What does the P-wave represent?
Atrial depolarization.
What does the QRS complex represent?
Ventricular depolarization.
What does the T-wave represent?
Ventricular repolarization.
What is atrial repolarization?
Repolarization of the atria.
What is hemoglobin?
Iron-protein molecule that transports oxygen and buffers blood pH
What is the function of red blood cells?
Contain hemoglobin and facilitate CO2 removal
What are arteries?
Large tubes that rapidly transport blood from the heart
What are arterioles?
Small tubes that branch off the arteries and control the blood before entering the capillaries
What are capillaries?
Smallest tubes that facilitate exchange of O2, CO2, and nutrients between blood and tissues
What are venules?
Collect blood from capillaries and transport it to veins
What are veins?
Larger tubes that return blood to the heart
What is the difference between the walls of arteries and veins?
Arteries have stiff walls to contain the high pressure of blood from the heart. Veins have thinner, dilatable walls that constrict or expand depending on the current needs of the body
What is the function of capillaries?
Facilitate exchange of O2, CO2, and nutrients between blood and tissues
What is the respiratory system?
Series of passages for gas exchange
What is the function of nasal cavities?
Warm, purify, and humidify air
What is the trachea?
First-generation respiratory passage
What are bronchi?
Second-generation respiratory passages
What are bronchioles?
23 generations of passageways to alveoli
What are alveoli?
Location of gas exchange in lungs
What happens during normal inspiration?
Diaphragm contracts, creating negative pressure
What happens during normal expiration?
Diaphragm relaxes, elastic recoil expels air
What muscles are used during heavy breathing?
Intercostals, sternocleidomastoids, anterior serrati, scaleni
What are pleural membranes?
Surround lungs with negative pressure
What is alveolar pressure?
Pressure inside lung alveoli
When does alveolar pressure fall?
During inspiration
When does alveolar pressure increase?
During expiration
