BY 312 Lecture (3/20)

Overview of Class Discussions

  • The pace of the anatomy course and upcoming assessments.
  • Conflict in dates for the research presentation and psychology project due dates.

Key Dates and Assessments

  • Research Presentation: Ensure clarity on the date and any scheduling conflicts.
  • Class Quiz: Scheduled for Monday, covering material discussed today.
  • Online Test: Due by Wednesday at midnight.

Circulatory System and Blood Pressure

Autoregulation and Circulation

  • Autoregulation: Mechanism by which blood vessels respond to changes in blood flow and oxygen demand.
  • Differences in Circulatory Systems:
    • Systemic Circulation: Systemic blood vessels dilate in response to:
    • Hypoxia (low oxygen levels).
    • Acidosis (increased acidity).
    • Increases blood flow to tissues needing oxygen.
    • Pulmonary Circulation: Opposite response; pulmonary blood vessels constrict to divert flow to better ventilated lung areas.

Measuring Circulation: Pulses

  • Pulses: Result from alternate expansion and recoil of elastic arteries post-systole.
  • Common Pulse Points:
    • Superficial temporal artery.
    • Facial artery.
    • Common carotid artery (often used).
    • Brachial artery (for blood pressure measurements).
    • Radial artery (for radial pulse).
    • Femoral artery.
    • Popliteal artery (difficult to palpate).
    • Dorsalis pedis (important for assessing circulation to feet).

Blood Pressure Basics

  • Definition: Force of blood against arterial walls generated by the left ventricle during systole and maintained during diastole.
  • Systolic Pressure: The first sound heard when measuring (during cuff pressure release).
  • Diastolic Pressure: The last sound heard (when sound disappears).
  • Krotkoff Sounds: Sounds used to measure blood pressure.

Hypertension (High Blood Pressure)

  • Prevalence: Affects about 45 million Americans, representing the most common cardiovascular disorder.
  • Consequences of Chronic Hypertension:
    • Atherosclerotic disease.
    • Heart failure.
    • Kidney disease.
    • Increased risk of stroke.
  • Complications: Left ventricular hypertrophy, glomerulosclerosis, aneurysms, and hypertensive strokes.
  • Classification of Blood Pressure:
    • Normal: 120/80 mmHg.
    • Elevated: 120-129/ <80 mmHg.
    • Stage 1 Hypertension: 130-139/80-89 mmHg.
    • Stage 2 Hypertension: 140-159/90-99 mmHg.
  • Hypertensive Crisis: Blood pressure over 180/120 mmHg is critical, requiring immediate medical attention.

Types of Hypertension

  1. Primary Hypertension:
    • Accounts for 95% of cases.
    • No identifiable cause; persistently elevated without other underlying conditions.
  2. Secondary Hypertension:
    • Identifiable causes such as renal blood flow obstruction or adrenal glands overproducing catecholamines.

Implications

  • Asymptomatic Nature: Hypertension often termed a "silent killer"; many affected individuals show no symptoms until checked.
  • Vital Signs Importance: Regular checks can help identify and manage hypertension early.

Management of Hypertension

  1. Lifestyle Modifications:
    • Weight loss (adiposity increases blood vessel volume and pressure).
    • Reduced alcohol consumption.
    • Regular exercise lowers blood pressure.
    • Decrease in sodium intake reduces risk of hypertension.
    • Adequate dietary intake of calcium, magnesium, potassium.
    • Smoking cessation.
    • Stress management techniques.

Hypotension (Low Blood Pressure)

  • Defined as insufficient pressure for adequate blood flow.
  • Asymptomatic individuals with low blood pressure are not generally considered hypotensive.
  • Symptoms like dizziness or fatigue indicate potential health issues when experienced with hypotension.

Shock

  • Definition: Failure of the cardiovascular system to provide sufficient oxygen and nutrients to meet metabolic needs.
  • Types of Shock:
    1. Hypovolemic Shock: Due to blood volume loss.
    2. Cardiogenic Shock: Poor heart function.
    3. Obstructive Shock: Obstruction in blood flow.
    4. Vascular Shock: Excessive vasodilation (e.g., anaphylaxis, sepsis).
  • Septic Shock: A severe bacterial infection leading to decreased blood pressure and high mortality rates in critical care.

Body Response Mechanisms to Shock

  • Increased heart rate and contraction strength as compensatory actions.
  • Hormonal responses (e.g., ADH, renin) activate blood volume conservation mechanisms.
  • Critical Care: Often requires fluid resuscitation and medications like epinephrine to restore perfusion.

Circulatory Routes

Systemic vs. Pulmonary Circulations

  • Pulmonary Circulation: Transports deoxygenated blood to lungs for reoxygenation.
  • Systemic Circulation: Delivers oxygen-rich blood from the heart to the body.
  • Bronchial Circulation: Supplies oxygenated blood to lung tissues (distinct from pulmonary circulation).

Arteries and Their Functions

Key Arteries to Know

  1. Aorta and its branches:
    • Supplies blood to the body.
  2. Brachiocephalic artery: Right side of head and neck.
  3. Common carotid arteries: Head and neck supply.
  4. Subclavian artery: Supplies upper extremities through various branches.
  5. Renal arteries: Supply kidneys.
  6. Femoral artery: Main artery for lower limb blood supply; often used for cardiac catheterization.
  7. Popliteal artery: Important for assessing circulation in lower limbs.

Clinical Notes on Specific Arteries

  • Internal Thoracic Artery: Frequently used in coronary artery bypass grafting due to its length and accessibility.
  • Clinical notes highlight potential conditions or complications related to specific arteries.

Conclusion

  • Emphasis on the need for continuous review and understanding of the arterial supply and circulatory paths. Importance of clinical application noted through mechanisms, management, and various circulatory conditions.
  • Reminder to prepare for upcoming quizzes and tests, with a focus on understanding both normal and pathological states of circulation.