Ex. Physiology Exam 1 - Dr. Karp

Phosphagen System (ATP-CP)

-ability to regenerate ATP using creatine phosphate.

-no carbs or fat used.

-anaerobic

-fastest way to resynthesizes ATP

-all out exercise up to 10 seconds

-fatigue occurs rapidly

Anaerobic Glycolysis

-breakdown of glucose

-ability to regenerate ATP through glycolysis

-2nd fastest way to resynthesizes ATP

-all out exercise from 30 sec - 2 min

-fatigue occurs from increase in hydrogen ions

Lactic Acid

-discovered in 1780

-”at physiological pH, lactic acid exists as lactate”

-supports production of ATP from glycolysis

-used as fuel by the heart

-used by liver to make glucose

Myths about Lactic Acid

-causes fatigue, muscle burning, soreness

Aerobic System

-aerobic

-uses carbs and fat

-slowest way to resynthesizes ATP

-all out exercise longer than 2 min

-produce 19 times more ATP than glycolysis

-fatigue occurs due to lack of oxygen

Calories

-the fundamental determinant of body weight is caloric balance

• Carbs = 4 cal/g

• Proteins = 4 cal/g

• Fat = 9 cal/g

-amount of heat energy needed to raise the temp of 1g of water by 1 degree Celcius

Metabolism

as intensity increases, rely less on fat and more on carbs.

EPOC

-excess post-exercise oxygen consumption

-EPOC elevated during longer duration

Body Weight

-more running = lower BMI and circumference

Heart

-pumps blood

-cardiovascular endurance is the most important component

Sinoatrial Node (SA Node)

sets the heart rate

What influences stroke volume?

heart contractility, preload, venous return, left ventricle size, afterload

Purkinje fibers

transmits impulse into ventricles

P-wave

depolarization of the atria

QRS Complex

depolarization of the ventricles

T-wave

repolarization of the ventricles

What is the resting cardiac output in a healthy, fit individual?

5L

At Max Cardiac Output (Males)

Non-active: 15-20L/min

Trained: 30L/min

Elite: 35-40L/min

At Max Cardiac Output (Females)

Non-active: 15-20L/min

Trained: 20-25L/min

Elite: 25-30L/min

Partial Pressure of Carbon Dioxide (PCO2)

main stimulus to breathe more heavily during exercise in your blood.

Hemoglobin

-4 protein subunits: 1 oxygen molecule

-transports oxygen from the lungs to muscles/other organs

Affinity of hemoglobin

facilitates the loading of O2 in the lungs and unloading of O2 in muscles or other organs.

Sympathetic

-excitatory

-vasoconstriction (contraction of the vessels)

Parasympathetic

-calming

-vasodilation (dilation of the vessels)

a-v O2 difference

-difference in oxygen between arterial blood and venous blood.

-influenced by the mitochondria

Arteries

-muscular, elastic

-thick layers allow them to withstand high pressures

Systolic

-BP during contraction

Diastolic

-BP during relaxation

Veins

-can expand to hold more blood

-pressure is low (2 mmHg), insufficient to return blood to heart bc of gravity.

-one-way valves (blood goes in one direction)

Varicose veins

-accumulation of blood in the veins that cause bulging

How does blood return to the heart is venous pressure is low?

-one-way valves

-muscle contraction serves as a pump

-inhalation sucks blood

Which substrate minimally contributes to ATP production?

proteins

Where does the electron transport chain occur in the cell?

mitochondria

Energy System from fastest to slowest

Phosphagen, Glycolysis, Aerobic

What happens in the electron transport chain?

fat is used for energy and ATP is produced

Production of ATP molecules

-aerobic (x19)

-anaerobically (x2)

What is the function of the respiratory system?

-supply oxygen and remove carbon dioxide from exercising muscles

-passive diffusion

What stimulates ventilation?

-an increase in CO2 and reduction of O2 in arterial blood.

What does tidal volume equal?

ventilation (VE) divided by breathing frequency

Residual Volume

-what is leftover in the lungs

Vital Capacity

inspiratory reserve volume + tidal volume + expiratory reserve volume

Boyle’s Law

-inverse relationship b/t volume and pressure

-atmospheric/barometric pressure is greater outside the body at sea level.

Inspiration

-active process (ATP)

-creates negative pressure in the lungs

-expansion of thoracic cavity

Expiration

-passive process

-creates positive pressure in the lungs

-relaxation of respiratory muscles

Mechanoreceptors

sense movements/body mechanics

Chemoreceptors

sense chemical stimulus

Pulmonary Diffusion

-O2 diffusion

• alveoli → blood

-CO2 diffusion

• blood → alveoli

-pressure is the driving force (high to low)

Alveolar-Capillary Interface

-ideal for gas exchange

-max. surface area in a small space

-driving force determined by partial pressure of gas

-Pgas = barometric pressure x [gas]

What is barometric pressure at sea level?

760 mmHg

Oxyhemoglobin Dissociation Curve

-Lungs

• blood exposed to high pressure

• O2 binds to Hb

-Tissue

• blood exposed to low pressure

• O2 released from Hb

Haldane Effect

oxygen displaces CO2 due to blood having lower affinity

Bohr Effect

decreased pH and increased temperature in muscle facilitating the unloading of oxygen

Pathogenesis of blood through the circulatory system

L. ventricle → aorta → arteries → arterioles → capillaries → muscle → capillaries → venule → veins → vena cava → R. atrium → R. ventricle → lungs → L. atrium → L. ventricle

What is the most important physiological test?

VO2max

VO2max

-maximum volume of oxygen consumed per minute

-occurs when stroke volume, heart rate, and a-v O2 difference are at maximum.

• cardiac output (heart pumps blood) → blood flow (transport) → muscle O2 use (metabolism through aerobic system)

Where in the muscle is O2 used?

mitochndria

Fick Equation

VO2 = SV x HR x (a-v O2 difference)

Why do males have larger VO2max values?

-male have larger stroke volume (larger heart)

-their L. ventricle can hold more blood.

-males have more hemoglobin (greater ability to transport O2)

What happens to our VO2max as we age?

-maximum heart rate decreases as we age, therefore VO2max decreases

Central (cardiac) vs. Peripheral (muscles) Limitation

-unfit people are equally limited by both central and peripheral factors.

Are highly trained athletes more centrally or peripherally limited?

-central

-training causes you to move away from metabolic limitation and closer to oxygen supply limitation

What improves VO2max?

-progressive increase in aerobic exercises because it increases the muscles metabolic capacity.

• improves Krebs Cycle and Electron Transport Chain activity

What is the VO2max of the best human endurance athletes?

80-90 ml/kg/min

What has the highest VO2max relative to their size?

flying insects

What athlete has the highest VO2max in humans?

cross country skiers

What is lactate threshold?

-highest exercise intensity above which blood lactate concentration increases exponentially.

-highest that can be sustained aerobically.

Acidosis threshold

as exercise intensity increases….contribution of fat decreases and carbohydrates increases.

Running Economy

oxygen consumption (VO2) used to maintain a specific running speed

VO2 vs Economy

The lower the VO2 at a given speed, the less O2 at a give speed, meaning it is more economical

Where do we see a plateau in VO2?

Submaximal speeds below the lactate threshold

Influencing factors of running economy

-biomechanics & motor unit recruitment

-mitochondrial density

-slow-twitch fibers

-body weight & leg mass

-storage & use of elastic energy

What are some external factors of running economy?

-clothing

-shoe weight

-wind & air resistance

-terrain

What percentage of max. heart rate does lactate threshold occur in a person of average fitness?

75%

Which of the following is a likely VO2max in a young, recreationally active female?

40 ml/kg/min

What is the function of the heart’s left ventricle?

to pump oxygenated blood to all of your organs except the lungs

At exercise intensities below the lactate threshold, what fuel does your muscles use?

carbohydrates and fats