Exercise Physiology: Hormonal, Circulatory, Neural, and Respiratory Responses

What is the role of the neuroendocrine system?

It integrates the functions of the endocrine system, which releases hormones into the blood, and the nervous system, which uses neurotransmitters to relay messages.

How do hormones exert their effects?

Hormones bind to specific protein receptors on target tissues.

What determines the effect of a hormone on a tissue?

The effect is determined by the plasma concentration of the hormone and the number of active receptors.

What factors influence plasma hormone concentration?

Rate of secretion, rate of metabolism/excretion, quantity of transport proteins, and changes in plasma volume.

What is downregulation in hormone receptor interactions?

It is the decrease in receptor number in response to high concentrations of a hormone.

What is upregulation in hormone receptor interactions?

It is the increase in receptor number in response to low concentrations of a hormone.

What are the mechanisms of hormone action?

Activation of genes to alter protein synthesis, activation of second messengers via G proteins, and altering membrane transport.

What is the function of growth hormone (GH)?

GH is essential for the growth of all tissues, stimulates amino acid uptake and protein synthesis, and promotes long bone growth.

How does growth hormone affect glucose levels?

GH opposes insulin action, reduces plasma glucose usage, increases gluconeogenesis, and mobilizes fatty acids.

What hormones are secreted by the anterior pituitary gland?

ACTH, FSH, LH, MSH, TSH, prolactin, and GH.

What is the role of oxytocin?

Oxytocin is involved in childbirth and lactation, and it is secreted by the posterior pituitary gland.

What is the primary hormone in plasma calcium regulation?

Parathyroid hormone (PTH).

What hormones are secreted by the adrenal medulla?

Epinephrine and norepinephrine, which are fast-acting hormones involved in the fight or flight response.

What is the function of aldosterone?

Aldosterone controls sodium reabsorption and potassium secretion, regulating blood volume and pressure.

What is the role of cortisol during exercise?

Cortisol maintains plasma glucose levels, promotes protein breakdown for gluconeogenesis, and mobilizes free fatty acids.

How does skeletal muscle act as an endocrine organ?

It produces myokines during contractions that stimulate glucose uptake, fatty acid oxidation, and promote blood vessel growth.

What is the effect of insulin during exercise?

Insulin promotes the uptake and storage of glucose and free fatty acids, but its plasma concentration decreases during exercise.

What is the role of glucagon during exercise?

Glucagon promotes the mobilization of glucose and free fatty acids, with plasma concentration increasing during exercise.

What is the effect of epinephrine on muscle glycogen utilization?

Epinephrine stimulates glycogenolysis, particularly during high-intensity exercise.

What is the relationship between exercise intensity and glycogen depletion?

Higher intensity exercise results in greater and more rapid glycogen depletion.

What is hormone-sensitive lipase (HSL)?

HSL is an enzyme that mobilizes free fatty acids, and its activity can be inhibited during heavy exercise.

What is the effect of thyroid hormones during exercise?

Thyroid hormones act permissively to enhance the effects of other hormones, but their levels do not significantly change during exercise.

What is the impact of regular exercise on inflammation?

Regular exercise promotes an anti-inflammatory environment, reducing chronic inflammation and the risk of diseases.

What are myokines?

Myokines are cytokines produced by skeletal muscle that have various effects on metabolism and inflammation.

What is the role of leptin?

Leptin suppresses appetite and enhances insulin sensitivity, but higher levels are associated with obesity and type 2 diabetes.

What is the primary function of the pancreas?

The pancreas has both exocrine and endocrine functions, secreting insulin, glucagon, and digestive enzymes.

What is the significance of the hypothalamus in hormone regulation?

The hypothalamus controls the secretions of the pituitary gland through releasing hormones.

What are the effects of high doses of growth hormone?

High doses can result in more adverse effects than benefits, with minimal strength gains compared to resistance training alone.

What is the relationship between cortisol and exercise intensity?

Cortisol levels decrease during low-intensity exercise but increase during high-intensity exercise.

What is the role of interleukin 6 (IL-6) during exercise?

IL-6 has both pro-inflammatory and anti-inflammatory effects, promoting an anti-inflammatory response during exercise.

What is the effect of catecholamines on insulin and glucagon secretion?

Catecholamines influence the secretion of insulin and glucagon, particularly during exercise.

What clinical condition can occur in ultra-endurance events when only water is used to replace fluid loss?

Hyponatremia

What dietary condition increases the rate of amino acid utilization during exercise?

Low carbohydrate diet

Which diet is associated with the highest muscle glycogen levels?

High carbohydrate diet

What percentage of carbohydrate is typically recommended in a balanced diet for athletes?

6-8%

What is the duration of exercise that can lead to hyponatremia if only water is consumed?

4+ hours

What is VO2 max?

The maximal amount of oxygen the body can consume during maximal exercise; best indicator for cardiorespiratory and aerobic fitness.

What equation is used to calculate VO2?

VO2 = heart rate stroke volume (a-v O2 difference).

What factors control stroke volume?

Preload, contractility, and afterload.

What does the arterial-venous oxygen difference measure?

The extraction of oxygen as it passes through the tissue.

What is absolute VO2?

Total oxygen consumed per minute (L/min).

What is relative VO2?

Oxygen consumption standardized to the size of the subject (ml/kg/min).

What are the five criteria for determining if a valid VO2 max has been achieved?

1. Plateau in VO2 despite increasing work rate, 2. Heart rate within 10 beats/min of age-predicted HR max, 3. RER > 1.1, 4. Blood lactate concentration > 70-80 mg/100 ml, 5. RPE > 17.

What is the formula for age predicted maximal heart rate?

HR max = 208 - (0.7 x age).

What is the primary function of the cardiorespiratory system?

To transport O2 and nutrients to tissues and remove CO2 and wastes.

What is the difference between the pulmonary and systemic circuits?

The pulmonary circuit pumps deoxygenated blood to the lungs, while the systemic circuit pumps oxygenated blood to the body.

What is the myocardium?

The heart wall, consisting of the endocardium, myocardium, and epicardium.

What is myocardial infarction (MI)?

Blockage in coronary blood flow that results in cell damage.

How does regular exercise affect heart health?

It reduces the incidence of heart attacks and improves survival from heart attacks.

What happens during systole?

The heart contracts and ejects blood.

What happens during diastole?

The heart relaxes and fills with blood.

What is typical arterial blood pressure?

120/80 mmHg.

What is hypertension?

Blood pressure above 140/90 mmHg.

What are the determinants of mean arterial pressure (MAP)?

Cardiac output and total vascular resistance.

What is the role of the sinoatrial node (SA node)?

It acts as the pacemaker, initiating depolarization.

What does an electrocardiogram (ECG) record?

The electrical activity of the heart.

What does the P wave in an ECG represent?

Atrial depolarization.

What does the QRS complex in an ECG represent?

Ventricular depolarization and atrial repolarization.

What does the T wave in an ECG represent?

Ventricular repolarization.

What is cardiac output (Q)?

The amount of blood pumped by the heart each minute.

What is the relationship between heart rate and stroke volume?

Cardiac output = heart rate * stroke volume.

What is the effect of the sympathetic nervous system on heart rate?

It increases heart rate by stimulating the SA and AV nodes.

What is heart rate variability (HRV)?

The time between heartbeats, indicating balance between SNS and PNS.

What is the Frank-Starling principle?

Greater end-diastolic volume results in a more forceful contraction due to stretch of ventricles.

What is the role of nitric oxide in blood flow?

It promotes smooth muscle relaxation, resulting in vasodilation.

What is the effect of exercise on blood flow distribution?

Increased blood flow to working skeletal muscle and decreased flow to less active organs.

What is cardiovascular drift?

Gradual increase in heart rate during prolonged exercise, particularly in heat.

What is the central command theory?

The initial signal to drive the cardiovascular system comes from higher brain centers.

What are the common causes of sudden cardiac death during exercise?

Abnormal heart rhythms due to genetic anomalies, cardiomyopathy, or coronary artery disease.

What is the impact of emotional states on heart rate and blood pressure?

Elevated HR and BP in emotionally charged environments due to increased SNS activity.

What happens to stroke volume in endurance athletes during high heart rates?

Stroke volume does not plateau and continues to improve due to enhanced ventricular filling.

What is the difference between absolute VO2 and relative VO2?

Absolute VO2 is total oxygen consumed per minute (L/min), while relative VO2 standardizes oxygen consumption to body size (ml/kg/min).

What are the main purposes of the cardiorespiratory system?

Transport O2 and nutrients to tissues, remove CO2 and wastes from tissues, and regulate body temperature.

How does exercise training protect the heart?

It reduces the incidence of heart attacks and improves survival from heart attack by enhancing antioxidant capacity and improving ATP-sensitive potassium channels.

What happens during systole and diastole?

Systole is the contraction phase where blood is ejected, while diastole is the relaxation phase where the heart fills with blood.

What is the typical arterial blood pressure reading?

120/80 mmHg.

What role do baroreceptors play in blood pressure regulation?

They detect changes in blood pressure and adjust sympathetic nervous system activity accordingly.

What is the conduction system of the heart?

It includes the SA node (pacemaker), AV node, bundle branches, and Purkinje fibers.

What does the P wave represent in an ECG?

Atrial depolarization.

What is the relationship between cardiac output, heart rate, and stroke volume?

Cardiac output (Q) = heart rate (HR) * stroke volume (SV).

What factors influence heart rate during exercise?

Parasympathetic and sympathetic nervous system activity.

What is the Frank-Starling mechanism?

Greater end-diastolic volume (EDV) results in a more forceful contraction due to ventricular stretch.

How does blood flow change during exercise?

Blood flow increases to working muscles and decreases to less active organs.

What is nitric oxide's role in the circulatory system?

It is a vasodilator that promotes smooth muscle relaxation and increases blood flow.

What is the effect of emotional stress on heart rate and blood pressure?

It can elevate heart rate and blood pressure due to increased sympathetic nervous system activity.

What can sudden cardiac death during exercise be attributed to?

Abnormal heart rhythms caused by genetic anomalies, cardiomyopathy, or coronary artery disease.

What is the significance of hematocrit in blood doping?

A hematocrit greater than 50% may indicate blood doping using EPO.

What is the muscle of the heart called?

Myocardium.

What is the role of the coronary arteries?

They supply blood to the myocardium, which has a high demand for oxygen and nutrients.

What is the role of venous return in stroke volume?

Increased venous return enhances end-diastolic volume, leading to a more forceful contraction.

What is the relationship between blood flow, pressure, and resistance?

Blood flow is directly proportional to the pressure difference and inversely proportional to resistance.

What is the effect of exercise intensity on blood flow redistribution?

Blood flow is redistributed from inactive organs to working skeletal muscle based on metabolic demands.

What is the term for a hematocrit greater than 50%?

It indicates a higher concentration of red blood cells in the blood.

Where within the arterial tree is the greatest resistance to blood flow found?

Arterioles

How does exercise training benefit the heart during a heart attack?

It helps to resist or attenuate permanent damage.

What are the general functions of the nervous system?

Control of the internal environment, voluntary control of movement, programming spinal cord reflexes, and assimilation of experiences for memory and learning.

What are the two main divisions of the nervous system?

Central nervous system (CNS) and peripheral nervous system (PNS).

What does the central nervous system consist of?

The brain and spinal cord.

What is the role of afferent fibers in the sensory division of the PNS?

They transmit impulses from receptors to the CNS.

What do efferent fibers in the motor division of the PNS do?

They transmit impulses from the CNS to effector organs.