9.3 - Hormonal Regulation of Stress and Blood Sugar

Recap Questions

• Negative Feedback System for T3 and T4

  • Regulates hormone levels in the blood.

  • T3 and T4 stimulate metabolic processes.

• Humoral Stimulation of Thyroid and Parathyroid Glands

  • Regulates calcium ion levels.

  • Antagonistic hormones work to maintain balance.

9.3 Hormonal Regulation of Stress and Blood Sugar

Regulation of Stress

Adrenal Gland

• Location: On top of the kidneys.

• Structure: Inner layer (adrenal medulla) and outer layer (adrenal cortex).

Adrenal Medulla: Short-Term Stress Response

• Fight or Flight response.

• Hormones Produced: Epinephrine and norepinephrine.

• Stimulus: Neural signal from the hypothalamus.

  • Direct stimulation of the adrenal medulla.

Stress Response: Short Term

• Physiological Effects:

  • Increase in heart rate and blood pressure.

  • Rise in blood glucose levels.

  • Energization of muscles.

Adrenal Medulla Function

• Rapid physiological responses include:

  • Increase in breathing rate and heart rate.

  • Blood flow redirected to the heart and muscles.

  • Short-lived increase in glucose availability via liver glycogen conversion.

  • Dilation of pupils and decrease in blood flow to extremities.

Adrenal Cortex: Long-Term Stress Response

• Hormones Produced: Glucocorticoids (cortisol) and mineralocorticoids (aldosterone).

• Regulation Pathway:

  • Corticotropin Releasing Hormone (CRH) -> Adrenocorticotropic Hormone (ACTH) -> Adrenal Cortex

Adrenal Cortex Function

• Sustained physiological responses:

  • Cortisol: Raises blood glucose and suppresses immune functions.

  • Aldosterone: Increases sodium reabsorption in kidneys, raising blood pressure.

Long term vs Short term stress response

• Short term:

  • Rapid, brief control, quick energy use.

• Long term:

  • Sustained effects increasing blood pressure, heart rate, and metabolism.

Chronic Stress Effects

• Sustained cortisol and aldosterone levels:

  • Impairments in cognition (memory recall).

  • Hypertension and high blood sugar (diabetes).

  • Increased vulnerability to infections, anxiety, depression, weight fluctuations.

  • "Karoshi": Japanese term for death due to overwork.

Addison’s Disease

• Condition of adrenal gland damage:

  • Insufficient secretion of mineralocorticoids and glucocorticoids.

  • Symptoms include hypoglycemia, rapid weight loss, and electrolyte imbalance.

• Historical Note: JFK suffered from Addison's, managed with hormone injections.

Regulation of Blood Sugar

Pancreas

• Contains endocrine cells:

  • Alpha (glucagon) and beta (insulin) cells.

Hormonal Regulation of Blood Sugar

• Insulin Functions:

  • Liver stores glucose as glycogen.

  • Muscle cells convert glucose into glycogen and proteins.

  • Adipose tissue uses glucose for fat.

• Blood glucose homeostasis:

  • Normal levels: 75 - 110 mg/100 mL blood.

• Glucagon Functions:

  • Secretes when blood glucose is low to increase glucose availability.

Diabetes Mellitus

• Condition characterized by high blood glucose levels post-meals (hyperglycemia).

Types of Diabetes

• Type I:

  • Occurs in childhood; abrupt onset; caused by degeneration of beta-cells leading to no insulin production.

• Type II:

  • Manifests in adulthood; gradual onset; characterized by insulin resistance.