The body's ability to correct an excess or deficit of a metabolic acid depends on normal function of what system?

Stress can increase the basal metabolic rate (BMR) due to the release of stress hormones like adrenaline and cortisol, which can increase the body's energy expenditure.

Stress Response Mechanism

1. Brain and Pituitary Gland:
   • The stress response begins in the brain, specifically the hypothalamus, which signals the pituitary gland to release adrenocorticotropic hormone (ACTH).
2. Adrenal Glands:
   • ACTH travels through the bloodstream to the adrenal glands, located above the kidneys. The adrenal glands then release cortisol and adrenaline into the bloodstream.
3. Cortisol and Adrenaline Effects:
   • Cortisol:
     • Cortisol increases glucose production in the liver by converting glycogen (the stored form of glucose) to glucose, making more energy available to the body.
     • It also promotes protein breakdown into amino acids, which can be converted to glucose, further increasing energy availability.
   • Adrenaline (Epinephrine):
     • Adrenaline increases heart rate and blood pressure, enhancing the delivery of oxygen and nutrients to tissues.
     • It stimulates glycogenolysis (the breakdown of glycogen to glucose) and lipolysis (the breakdown of fat into fatty acids), providing additional energy sources.
4. Physiological Changes:
   • Liver: Converts glycogen to glucose, increasing blood glucose levels.
   • Heart: Accelerated heart rate and increased blood pressure improve oxygen and nutrient delivery.
   • Lungs: Increased breathing rate (fast breathing) ensures more oxygen enters the bloodstream.
   • Sweat Glands: Increased sweating helps cool the body.
   • Digestive System: Digestion slows down, conserving energy for more immediate demands.
   • Vision: Tunnel vision may occur as the body focuses on immediate threats.

Impact on Basal Metabolic Rate (BMR)

The combined effects of cortisol and adrenaline lead to an increase in BMR. The body’s energy expenditure rises due to:

• Increased Glucose and Fat Availability: Enhanced breakdown of glycogen and fats provides more fuel for cellular metabolism.
• Heightened Cardiovascular Activity: Increased heart rate and blood pressure raise energy demands.
• Enhanced Cellular Activity: The overall increase in cellular processes, including metabolism and energy production, results in higher energy expenditure.

The autonomic nervous system controls the firing of the sinus node (sinoatrial node) by regulating heart rate and rhythm. It adjusts the rate at which the sinus node generates electrical impulses, influencing the start and pace of the cardiac cycle.