I1. 1a CARDIO - Function, Size, Form, and Location of the Heart

11.1a CARDIO - Function, Size, Form, and Location of the Heart

Objectives

  • Students should be able to:

    1. List the major functions of the heart.

    2. Describe the size, shape, and location of the heart.

    3. Explain why knowing the heart's location is important.

    4. Determine the implications of A&P (Anatomy & Physiology) to Nursing Practice.

Cardiovascular System

Components

  • Heart

    • Acts as the central pump for circulation.

  • Blood Vessels

    • Form a closed network carrying blood throughout the body.

  • Blood

    • Transports vital substances to and from cells.

  • Clinical Relevance

    • Cardiovascular diseases can affect any component of this system.

    • Diagnostic tests often target specific components for disease assessment.

Functions of the Heart

Major Functions

  1. Oxygen/Nutrient Delivery

    • Vital for cellular metabolism, maintains homeostasis.

  2. Waste Removal

    • Critical in eliminating metabolic waste.

  3. Hormone Transport

    • Supports the endocrine system by distributing hormones.

  4. Temperature Regulation

    • Helps maintain body temperature by adjusting blood flow.

  5. pH Balance

    • Regulates blood pH to keep it within normal limits.

Clinical Relevance

  • Dysfunction can lead to systemic issues, and many diseases manifest through cardiovascular symptoms.

Circulatory Pathways

  1. Pulmonary Circulation

    • Pathway: Heart ➡️ Lungs ➡️ Heart

    • Affected by pulmonary hypertension.

  2. Systemic Circulation

    • Pathway: Heart ➡️ Body ➡️ Heart

    • Affected by systemic hypertension.

Structure of the Heart

  • Four Chambers

    • 2 Atria and 2 Ventricles.

  • Heart Valves

    • Ensure one-way blood flow; disorders may cause murmurs or valve-related issues.

  • Chamber Functions

    • Right side: deoxygenated blood; Left side: oxygenated blood.

    • Chamber enlargement indicates heart stress.

Blood Vessels

  1. Arteries

    • Carry blood away from the heart.

  2. Veins

    • Return blood to the heart.

  3. Capillaries

    • Site for substance exchange.

Clinical Relevance

  • Atherosclerosis impacts arteries; deep vein thrombosis occurs in veins; capillary disorders affect tissue perfusion.

Key Function Details

Major Functions

  1. Generating Blood Pressure

    • Heart muscle contractions create pressure.

    • Left ventricle generates highest pressure; can lead to hypertension or hypotension symptoms.

  2. Routing Blood

    • Separates pulmonary and systemic circuits; congenital defects may disrupt this routing.

  3. Ensuring One-way Blood Flow

    • Heart valves are critical; defects can lead to regurgitation.

  4. Regulating Blood Supply

    • Changes in heart rate and contractility meet varying tissue demands; heart failure impairs this.

Size, Form, and Location of the Heart

Size

  • Approximately the size of a closed fist; may be larger in active adults or indicate cardiomegaly if enlarged.

  • Declines after age 65 in less active individuals.

Shape

  • Shaped like a blunt cone with a rounded apex and broader base.

  • Abnormal heart shapes may be revealed through chest X-rays.

Location

  • Located in thoracic cavity between pleural cavities (mediastinum).

  • Majority of mass is left of midline; orientation is crucial for clinical procedures like auscultation and CPR.

Clinical Applications

  • Knowledge of heart structure and location aids in patient assessment, including ECG and imaging techniques.