21- Exercise Physiology Flashcards

Question

Pulmonary adjustments to exercise

Answer 1

Pulmonary responses to exercise – Meet increased needs for gas exchange – Exercise increases breathing by unknown mechanism Low work rates – IncreasedVentilationby increased tidal volume – More fresh air reaches the lung with each breath – Decreased dead space to tidal volume ratio Limit – Hightidalvolumes,lung compliance is reduced – Additional increases in ventilation are achieved to a greater extent by increasing breathing frequency

Answer 2

Homeostasis – 60% of maximal exercise capacity – Signal for the hyperpnea not from increased stimulation of carotid and intracranial chemoreceptors – During exercise above 60% of maximal capacity, • Lactacidosis • Hyperventilation of unknown cause

Answer 3

DLCO increasing – Recruitment of alveolar –capillary units – Increases the surface area for gas exchange. Increase in the A-a PO2 difference – Hyperventilation Increase in PAO2 – Driving pressure for diffusion of oxygen

Answer 4

• At Rest – Arterial-venous content difference is 5 vol% – Mixed venous PO2 is 40 mmHg ``` • During Exercise – Need for exchange is increased – Greater extraction of oxygen ---Decrease O2 bound to hemoglobin in venous blood ---Blood vessel (vasodilation) dilation – Arterial-venous content difference may exceed 15 vol% – Mixed venous PO2 is less than 20 mmHg ```

Answer 5

1) Neural, feed-forward : signal originates in the brain 2) Neural feedback: signal originates in muscles 3) Humoral: blood-born feedback

Answer 6

• Temperature control center receives input from thermo receptors in the skin (environmental temperature) • The hypothalamus (body temperature). • Regulation of body temperature during exercise – Hydration – Electrolyte balance ``` • Work results in conversion of energy to large amounts of heat – 98.6 ° (degrees) - 102° Fahrenheit • Heat loss – Vasodilation of arterioles in the skin – Heat transfer from the blood to the skin – To environment ---Sweating ---Evaporation ``` • Sweat production – Increased by the thermal control center in the hypothalamus – Increasing activity of sympathetic nerves to the sweat glands in the skin.

Answer 7

Principal pathways activated by stress: -hypothalamic-pituitary-adrenal axis and sympathetic nervous system increases in: - growth hormone - TSH - cortisol - catecholamines - glucagon - endorphins stimulation of: - hepatic glycogenolysis and gluconeogenesis - muscle glycogenolysis Suppressed release of: -insulin

Answer 8

Training : Enhances Athletic Performances – 2-3 days a week (4-6 weeks) Increase of work rate related to Intensity and Duration – Increase in maximal cardiac output primarily in stroke volume – Increased muscle and myocyte size – Increased vascularization of the heart Increased vascularization of skeletal muscle including – Locomotor muscles – Respiratory muscles – Enhanced blood delivery – Reduced diffusion distance for diffusion of gas ---Between the vasculature and the muscle Little evidence of respiratory system enhancement Enhances endocrine, thermoregulatory and metabolic responses to exercise - changes in sympathetic nerve activity - enhance mobilization of glucose and fatty acids - elimination of heat

Answer 9

Limiting factors to maximal O2 consumption Fatigue (mental or physical) – Boredom – Staleness – Drugs – Illness. – Depletion or non-availability of stores of energy – Accumulation of metabolic waste products – Alteration of physical-chemical state – Breakdown of homeostasis Highly elite endurance athletes can have a PaO2 of 60 mmHg during maximal exercise - at rest respiratory muscles only consume 2% of total O2 - at maximal exercise the respiratory muscle consumes nearly 25% of O2 consumption

Answer 10

as much as you can breathe in at once (forcefully)

Answer 11

amount you can exhale at once (forcefully)

Answer 12

- dissociation curve of capillary blood shifts to the right cause of a high CO2 - at any given O2 content, the diffusion gradient for O2 from the capillaries to tissues is greater than at rest