Chapter 1-7 Overview of Hypertension and Cardiac Physiology

Session Overview

  • Host: Lamia, assigned leader
  • Date and Time: Today from 11:00 to 11:50 AM
  • Location: Health Sciences 213
  • Session Type: Hybrid (in-person and Zoom)
  • Purpose: Practice questions and discussion for the exam on module three

Announcement

  • Worksheets available on WordPress for Human Physiology. Students encouraged to review before the session.
  • Instructor unavailable during office hours this Friday due to a faculty meeting.

Content Summary

  • Recap of lecture topics concluding with:
    • Coarctation of the Aorta
    • Preeclampsia
    • Thyroid Function and Disorders
    • Parathyroid Hormone and Calcium Regulation
    • General Signs of Hypertension
    • EKG Interpretation
    • Action Potentials in the Heart
  • Discussion of clinical case studies.

Detailed Content

Coarctation of the Aorta

  • Definition: Congenital maldevelopment of the aorta. A narrowing occurs just after the arch of the aorta.
  • Symptoms:
    • Hypertension in the head and neck due to decreased blood flow.
    • Low blood pressure in the lower limbs.
  • Treatment: Surgical intervention to remove the narrowed segment of the aorta.

Preeclampsia

  • Definition: Hypertension in pregnant women due to hormonal changes during pregnancy.
  • Mechanism: Hormonal changes alter the blood vessel wall, increasing the risk for hypertension.

Thyroid Hormones

  • Function: Regulate body metabolism and temperature while increasing sensitivity of
    • Alpha-1 and Beta-1 adrenergic receptors to norepinephrine.
  • Effect of Hyperthyroidism: Increases the risk for
    • Hypertension
    • Palpitations
    • Excess sweating
    • Arrhythmias

Parathyroid Hormone (PTH)

  • Function: Increases blood calcium levels.
  • Normal range: 10 ext{ mg/dL} for blood calcium.
  • Effects of Hypercalcemia:
    • Unfavorable for blood pressure stability and heart function.
    • Can lead to hypertension and arrhythmias.

General Signs and Symptoms of Hypertension

  • Common symptoms include:
    • Headaches
    • Nosebleeds
    • Vertigo
    • Anxiety
    • Excess sweating
    • Palpitations
  • Importance of determining the underlying cause of hypertension.
  • Potential causes and examples provided in discussions.

Treatments for High Blood Pressure

  • Medication Types:
    • Angiotensin-Converting Enzyme (ACE) Inhibitors
    • Example: Captopril, Ramipril
    • Angiotensin II Receptor Blockers
    • Example: Valsartan
    • Diuretics
    • Example: Hydrochlorothiazide
    • Calcium Channel Blockers
    • Example: Benzodiazepine
    • Beta Blockers
    • Example: Propranolol (beta-1 blocker)

EKG Interpretation

  • Components of EKG:
    • P Wave: Depolarization of the atria, duration of 0.08 - 0.1 ext{ seconds}.
    • PR Interval: Shows depolarization through AV node, duration of 0.12 - 0.2 ext{ seconds}.
    • Longer than 0.2 ext{ seconds} indicates AV node block.
    • QRS Complex: Depolarization and contraction of both ventricles, duration of 0.06 - 0.1 ext{ seconds}.
    • ST Segment: Indicates ventricles are relaxed after contraction; deviation indicates myocardial infarction.
    • T Wave: Represents relaxation phase of ventricles.

Action Potentials in the Heart

  • Phases of Ventricle Action Potential:

    • Phase 0: Sodium influx into the cell.
    • Phase 1: Potassium efflux begins.
    • Phase 2: Calcium influx occurs, maintaining depolarization.
    • Phase 3: Potassium efflux continues.
    • Phase 4: Return to resting membrane potential, -85 ext{ mV}, potassium equilibrium.

  • SA Node Action Potential Phases:

    • Phase 0: Calcium influx.
    • Phase 3: Potassium efflux.
    • Phase 4: Sodium influx, leading to depolarization.

Refractory Periods

  • Absolute Refractory Period:
    • No response to a second stimulus during Phase 0 (depolarization).
  • Effective Refractory Period:
    • Response efficacy changes in Phase 1 and Phase 2; no observable reaction despite effective stimulation.
  • Relative Refractory Period:
    • Possible reaction to a second stimulus during Phase 3 (recovery phase).

Clinical Case Studies

Case 1

  • Patient: 75-year-old male.
  • Symptoms: Severe hypertension, headache, increased sodium, decreased potassium, increased blood glucose.
  • Conclusion: Possible Cushing's syndrome.

Case 2

  • Patient: 75-year-old male.
  • Symptoms: Severe hypertension, headache, excess sweating, palpitations, significant weight loss of 20 pounds in a month.
  • Conclusion: Potential hyperthyroidism, differential diagnosis with pheochromocytoma based on weight loss.

Takeaways for Differential Diagnoses

  • Signs of hyperandrogenism and central obesity suggest Cushing's syndrome.
  • Elevated sodium and low potassium suggest contributions from aldosterone.
  • Weight loss is critical in diagnosing hyperthyroidism versus pheochromocytoma.

Other Important Notes

  • Clinical knowledge must integrate with physiology for accurate diagnosis and understanding of symptoms.
  • Importance of continual learning and application in future medical scenarios.

Closing

  • Reminder of the next session and thank you for participation.