Learning Checks

According to the “central governor” model, what primarily regulates fatigue?

The conscious and subconscious brain limiting exercise intensity

What physiological advantage do elite marathoners possess that allows them to maintain high speeds for long durations?

Ability to sustain a high %VO2max

What is the primary determinant of performance in ultra-endurance events?

VO2max and %VO2max that can be sustained

How does carbohydrate ingestion support long-term endurance performance?

It maintains carbohydrate oxidation and delays glycogen depletion

Why might antioxidant supplementation NOT prevent exercise-induced fatigue?

High doses can impair muscle performance

How does muscle fiber recruitment change as exercise intensity increases?

Type I → Type IIa → Type IIx

Why does lactate accumulation contribute to fatigue in high-intensity exercise?

It inhibits calcium binding to troponin, reducing muscle contraction efficiency

Which factor does NOT significantly impact aerobic performance in events lasting 1-4 hours?

Phosphocreatine availability

What is the primary energy system used for short-term performances (10-180 secs)?

Anaerobic glycolysis

How do muscle free radicals contribute to fatigue during prolonged exercise?

They promote contractile protein damage, reducing force production

What is the main factor limiting ultra-short-term performances (<10 secs)?

Rate of ATP regeneration from anaerobic pathways

How does excessive endurance training contribute to central fatigue?

It is associated with increased serotonin activity, leading to prolonged fatigue

What is a characteristic physiological sign of fatigue at the muscular level?

Longer muscle relaxation time

Why is the neuromuscular junction (NMJ) not considered a primary site of fatigue?

The NMJ does not experience action potential failure

Which best describes central fatigue?

Fatigue caused by factors within the central nervous system, affecting motor unit recruitment

Why do concurrent strength and endurance training programs result in lower strength gains?

Endurance training interferes with strength development

What is the most effective way to prevent DOMS after a new training stimulus?

Performing a second bout of the same exercise

What factor is the primary cause of DOMS?

Muscle tissue damage from eccentric contractions

Why is carbohydrate availability important for endurance training adaptations?

It promotes increased mitochondria formation

What is the primary goal of periodization in strength training?

Prevent overtraining and optimize strength gains

Why do men typically experience greater hypertrophy than women in response to strength training?

Men have higher testosterone levels

According to the “Ten Percent Rule”, how should athletes progress their training load?

Increase intensity or duration by 10% per week

What is a major risk of altitude training?

De-training due to reduced training intensity

What training principle best explains why an endurance runner should focus on high-intensity, continuous training rather than short sprints?

Specificity

What is the primary difference between HIIT and SIT?

SIT is performed at a supra-maximal intensity, exceeding VO2max

What is the primary goal of the warm-up phase in a training session?

Increase muscle temperature and blood flow

Which factor is NOT a primary determinant of endurance performance?

High anaerobic power

Why does anaerobic capacity have a stronger genetic component than aerobic capacity?

Anaerobic performance depends largely on fast-twitch (IIx) muscle fibers

How does initial fitness level influence training improvement?

Lower initial fitness results in greater percentage improvement

Which best describes the principle of overload in training?

Gradually increasing the stress placed on a system for adaptation

If an individual is exposed to a hot environment, which physiological response is most critical for temp regulation?

Vasodilation and increased sweating to promote heat loss

What would happen to insulin secretion during a period of counterregulation, such as prolonged fasting?

Insulin secretion would decrease to allow glycogenolysis and gluconeogenesis

What is a primary physiological purpose of shivering?

To generate heat through involuntary muscle contraction

Which would likely increase BMR?

• Fasting

• Sleep

• Increased thyroid hormone levels

• Aging

Increased thyroid hormone levels

Your pt with COPD comes into the clinic moving slowly and complaining of increased fatigue, and a headache, She wants to cancel her session. What might you suspect?

Respiratory acidosis

Why can heatstroke be fatal if untreated?

The body loses the ability to regulate temp, causing organ failure

Which is a mechanism of heat loss?

• BMR

• Skeletal muscle activity

• Radiation

• T3 and T4 hormones

Radiation

If the ambient temp increases and core temp remains normal, what would be expected?

Vasodilation of skin capillaries and veins

Which best explains the concept of glucose sparing during the postabsorptive state?

Most tissues switch to utilizing fatty acids and ketones, preserving glucose for the brain

How does fever differ from hyperthermia caused by exercise?

Fever results from a raised hypothalamic set point, while hyperthermia does not

A pt experiencing severe hypoglycemia due to insulin overdoes would likely exhibits symptoms similar to those of:

SNS activation, such as sweating and tremors

Why must BMI guidelines be interpreted with caution when assessing an individuals health

BMI does not account for variations in muscle mass and body composition

The pH where 50% of the buffer is in the base form and 50% is in the acid form

pK of the buffer

During the absorptive state, which of the following best describes the primary energy source for most body tissues

Glucose from dietary carbohydrates

A person has a tumor that continuously secretes excess insulin. Which effects would most likely occur

Increased glucose uptake by skeletal muscles and adipose tissue

What physiological changes occur when an individual acclimatizes to a hot environment?

Sweat production increases with lower salt concentration

ABG’s

pH 7.55 norm (7.35-7.45)

paO2 95 norm (80-100 mmHg)

PaCO2 22 norm (35-45 mmHg)

HCO3 26 meq/l norm (22-26 med/l)

What is happening here?

uncompensated respiratory alkalosis

If an individual has a chronic positive energy balance, what physiological adaptation is mostly likely to occur?

Increased leptin secretion leading to appetite suppression

The central thermoregulatory center is located in the

hypothalamus

A decreased in sweating, weak, and rapid pulse, headache, dizziness, body temp 102 degrees

heat exhaustion

Which is a physiological adaptation to heat?

increased sweat output

Which hormone is primarily responsible for stimulating lipolysis during the postabsorptive state?

glucagon

How do stress and exercise elicit similar hormonal responses?

Both increase glucagon, epinephrine , and cortisol to promote glycogenolysis and lipolysis

Which part of the nephron is primarily responsible for the majority of sodium ion reabsorption

Proximal convoluted tubule

If GFR decreases during exercise, how do the kidneys maintain electrolyte and fluid balance under these conditions

By increasing the filtration fraction and tubular reabsorption of sodium

How does exercise-induced sympathetic activation primarily affect glomerular filtration rate (GFR)

GFR decreases due to vasoconstriction of both afferent and efferent arterioles

Which part of the nephron actively transports chloride out of the filtrate, contributing to the concentration gradient in the medulla

Ascending limb of the Loop of Henle

Which of the following best describes the role of mesangial cells in the renal corpuscle

They provide structural support and regulate glomerular filtration

If a pt is excreting large amounts of potassium in their urine, which part of the nephron is most likely responsible for this regulation

Distal convoluted tubule and collecting duct

How does the loop of Henle contribute to urine concentration

By actively reabsorbing water in the descending limb and salts in the ascending limb

Why might an increase in creatinine concentration in the blood indicate kidney dysfunction

The kidney is failing to properly filter and excrete metabolic waste

Why does sodium excretion typicality decrease during exercise despite increased dietary sodium intake

increased sympathetic tone reduces renal perfusion and sodium filtration

Why does blood enter the glomerulus at high pressure

The afferent arteriole has a larger diameter than the efferent arteriole

Why does the descending limb of the loop of Henle allow only water reabsorption but not sodium ions

The descending limb has aquaporins for water transportation but lacks active ion transporters

If there were a structural abnormality preventing the renal corpuscle from functioning properly, which would likely be the first consequence

impaired blood filtration

During moderate exercise, which best explains the changes in sodium reabsorption in the kidney

Sodium reabsorption increases due to enhanced aldosterone activity and reduced GFR

What distinguishes the function of the afferent arteriole from the efferent arteriole in the nephron

The afferent arteriole brings blood into the glomerulus, while the efferent arteriole drains it

What would be the expected effect of prolonged vigorous exercise on renal handling of sodium and water

Decreased sodium excretion due to heightened aldosterone and ADH activity

What would happen if the filtration barrier in the renal corpuscle were damaged

Large proteins and blood cells would pass into the urine

Which portion of the nephron is primarily responsible for the reabsorption of essential nutrients and ions

proximal convoluted tubule

Why is the nephron referred to as the functional unit of the kidney

it is responsible for the process of filtration, reabsorption, and secretion

If the collecting duct were nonfunctional, what would be the immediate impact on urine formation

inability to regulate water balance

Which of the following best describes the primary function of the kidneys beyond water excretion

regulation of water and ionic composition, hormone secretion, and glucose production

What would happen if the ureters were blocked

Urine would build up in the kidneys, potentially causing damage

If bicarbonate reabsorption were impaired in the nephron, which process would be most directly affected

regulation of blood pH

Which part of the nephron is directly responsible for filtering blood plasma

renal corpuscle

What role does the renal pelvis play in urine transport

it serves as a funnel to direct urine into the water

If the vasa recta were to become nonfunctional, what would be the most likely consequence

impaired concentration of urine

What is the primary cause of the immune deficiency in AIDS?

Helper T cell destruction by HIV

How is resistance to infection influenced by stress?

Stress decreases immune function, increasing susceptibility to infection

What is the role of helper T cells in graft rejection?

They activate cytotoxic T cells to target the transplant

How does a cytotoxic T cell destroy infected or cancerous cells?

By secreting toxic enzymes directly onto the target cell

What is the role of IgA antibodies in the immune system?

They prevent pathogens from entering through mucosal surfaces

Which of the following is the most critical factor for resistance to infection?

Protein calorie malnutrition

What is the function of the major histocompatibility complex (MHC) in immune response?

It presents antigens to T cells for immune recognition

How does immune tolerance prevent autoimmune diseases?

By deleting self-reactive lymphocytes or rendering them non-responsive

Which cytokine is activated in systemic responses to infection, such as fever and appetite loss?

Interleukin-1 (IL-1)

What is the function of interferons during viral infections?

They prevent viral replication in host cells

Which class of antibodies is most effective against bacterial infections in extracellular fluid?

IgG

How does NK cell activity differ from antibody-dependent cellular toxicity (ADCC)?

NK cells kill cells directly by secreting toxic chemical, while ADCC involves antibodies

What is the function of IgM antibodies in immune response?

They are the first antibodies produced in response to an infection

How does complement “know” what cells to attack?

It binds to pathogens marked by antibodies

What is the primary role of helper T cells in antibody-mediated immunity?

They activate B cells and assist in antibody production

What triggers the classical complement pathway in adaptive immunity?

The binding of C1 to antibodies attached to antigens

What is the primary function of IgE antibodies?

They mediate allergic reactions and defense against multicellular parasites

What is the role of interleukin-2 (IL-2) in the immune response?

It activates cytotoxic T cells and promotes their proliferation

How does antibody-mediated immunity enhance phagocytosis?

By linking antibodies to pathogens, facilitating their engulfment by phagocytes

What process ensures that self-reacting T cells are eliminated during fetal and postnatal life?

Clonal deletion

What is the significance of chemotaxis in the immune response?

It directs neutrophils and monocytes to site of infection

Which anatomical barriers to infection provides both physical and biochemical defense?

Mucus in the respiratory tract