Exam 1

Anatomy

The study of an organisms structure or morphology

Physiology

the study of body function

Exercise Physiology

the study of how the body’s functions are altered when we are physically active (since exercise presents a challenge to homeostasis)

Sports Physiology

The branch of physiology that examines the body’s responses and adaptations to sports and exercise, focusing on performance enhancement and recovery.

(further applies the concepts of exercise physiology to enhancing sport performance and optimally training athletes)

Contribution of DB Dill

Helped write the 3rd edition the book The Physiology of Muscular Activity

Nobel Prize finding on energy metabolism

Conducted some of the first studies on runners

• understanding of whole body energy production

• Oxygen uptake

Book Life, Heat, and Altitude

Affect of altitude on performace

Contribution of Harvard Fatigue Lab

Established the field

How the environment affects physical performance

VO2 max and aging

endurance physiology

Measure O2 consumption and CO2 output

Integrated systems to study whole body response to stress

Acute effects of exercise

Individual bout of exercise

immediate response to, and sometimes its recovery from, a single exercise bout

includes changes in heart rate, breathing, and energy expenditure.

Chronic effects of exercise

regular exercise over a period of days and weeks, the body adapts

improve both exercise capacity and efficiency

results in adaptations such as increased strength, endurance, and overall fitness.

Ergometers (What are they? Different types, Uses)

Ergo: Work Meter: Measure

A device used to measure physical work output during exercise, commonly used in clinical and research settings for assessing cardiovascular and respiratory responses. An exercise device that allows the intensity of exercise to be controlled (standardized) and measured.

Types:

• Treadmills: walking and running

• Cycle ergometers: pedal in an upright (normal) or reclined position

• Arm ergometers: exercise while seated using arm movement (paralyzed leg down)

• Tethered swimming: measures power output while swimming in a controlled environment.

• Swimming flume: a water channel that allows for controlled swimming conditions and effective measurement of swimming performance.

Cross-sectional study (advantage)

a cross section of the population of interest (i.e., a representative sample) is tested at one specific time, and the differences between subgroups from that sample are compared.

Allows for quick data collection from a large population, facilitating the examination of relationships between variables at a specific point in time without requiring long-term follow-up. Provides insights into prevalence and associations of health outcomes.

Longitudinal study (advantage)

the same research subjects are retested one or more times after initial testing to measure changes over time in variables of interest.

Involves repeated observations of the same variables over time, which allows researchers to detect changes and developments in the subjects or variables. Useful for studying trends and long-term effects.

Skeletal muscle

The type of striated muscle tissue that is primarily responsible for voluntary movements of the body.

It is attached to bones by tendons and is characterized by a striped appearance under a microscope.

Over 600 in the body

Voluntary/ consciously controlled

Motor neuron tells muscle to contract via transmitters

• somatic nervous system

• Sarcoplasmic R. release Ca

Smooth muscle

Involuntary, unconscious control

Walls of blood vessels and internal organs

not striated

Cardiac muscle

Striated

Controls itself (assistence autonomic nervous system and endocrine system)

ONLY IN THE HEART

Structural arrangement of muscle tissues

• Connective tissue layers, epi-, peri-, & endo-mysium

• Fascicles, fibers, myofibrils 

Muscle fiber structure

• Sarcolemma

  • Muscle membrane (encloses the muscle)

• T-tubule

  • Transports sub. through muscle fiber

• Sarcoplasmic reticulum

  • Stores calcium (need to contact)

• Actin and myosin filaments

• Myofibrils are structural units

Sarco = muscle (flesh)

Myo = muscle

Myofibrils

• (allow muscle to contract) (muscle → fasciculi → muscle fiber → myofibril)

  • Actin & myosin

    • Activation allow for movement

  • Sarcomere

    • Smallest unit of a muscle

  • Z disks

  • Troponin

  • Tropomyosin

Actin filament

• Actin

• Myosin

  • 2 actin per myosin

  • Thick filament with globular head

• Tropomyosin

• Tropnin

Attached to z disk

z disk → z disk = sarcomere

Titin

Stablize actin filament

“winding firmament”

allows the fiber to twist (rotates actin)

increases force produced

reduces risk of muscle damage

What leads to muscle fiber action?

1) motor neuron release acetylcholine (ACh)

2) ACh binds to receptors on the sarcolemma.

3) initiates an action potential

4) action potential travels to the SR releasing Ca2+

5) Ca2+ binds to troponin on the actin filament, and the
troponin pulls tropomyosin off the active sites, allowing
myosin heads to attach to the actin filament.

Need Ca for muscle contraction

Sliding filament theory of muscle contraction (Steps involved from action potential propagation along sarcolemma to power stroke to re-uptake of calcium in SR)

The sliding filament theory describes how muscle contraction occurs through the interaction of actin and myosin filaments within the sarcomere. When activated by an action potential, calcium is released, allowing myosin heads to bind to actin, leading to a power stroke that shortens the muscle fiber.

Myosin head moves to the actin actin

movement of myosin = power stroke = contraction

After contraction, calcium is reabsorbed into the sarcoplasmic reticulum (SR), allowing muscle relaxation.

Myosin cross bridge: the myosin head is tightly bound to actin without ATP.

Rigor state: Myosin binds to actin without a conformational change, leading to rigidity.

ATP binds to myosin and causes the myosin head to detach from actin, allowing the cycle to repeat and muscle to relax.

Calcium: allows actin and myosin to “meet”

ATPase: enzyme that hydrolyzes ATP, providing energy for the myosin head to detach and re-cock during muscle contraction. (ADP + P) Free energy used to change myosin head (tlit)

Need for muscle contraction

ATP

• Fuel for the power stroke

Ca

• controls actin and myosin interaction (meet or not)

magnesium

How are muscle fibers distinguished?

• ATPase activity

• Motor unit differences

• Contraction speed

Effects of genes, aging & training on fiber type

Size principle of motor unit recruitment & relation to fiber type

Muscle actions

Factors that affect muscle force production