B1 L2 lecture - student copy

PRELIM - 2025

  • BIOSCI 1: Human AnaPhy

AGING AND HOMEOSTASIS

  • Objective: Describe general anatomical and physiological changes that occur with aging.

MEDICAL IMAGING

  • Objectives: Describe the principles and importance of medical imaging procedures in evaluating organ functions and diagnosing disease.

What is Medical Imaging?

  • Definition: Medical imaging refers to techniques and procedures used for creating images of the human body.

Common Medical Imaging Procedures

1. Radiography

  • Procedure: A barrage of x-rays passes through the body producing an image on x-ray-sensitive film.

  • Result: A two-dimensional image known as a radiograph or x-ray.

  • History: The 'X' in X-rays symbolizes the unknown as discovered by Wilhelm Röntgen in 1895.

2. Magnetic Resonance Imaging (MRI)

  • Procedure: The body is exposed to a high-energy magnetic field, causing protons to align.

  • Application: High-quality imaging of soft tissue and organs.

3. Computed Tomography (CT)

  • Formerly known as: Computerized Axial Tomography (CAT) scanning.

  • Procedure: An x-ray beam traces around a body section, producing a series of images.

  • Result: A transverse section visualized on a video monitor.

4. Ultrasound Scanning

  • Procedure: High-frequency sound waves reflect off body tissues.

  • Result: Production of a sonogram showing still or moving images displayed on a monitor.

5. Coronary (Cardiac) Computed Tomography Angiography (CCTA) Scan

  • Procedure: Iodine contrast medium is injected, and x-ray beams produce a 3-D image of coronary vessels.

  • Efficiency: Images generated in less than 20 seconds.

6. Positron Emission Tomography (PET)

  • Process: Radioactive substance is injected, emitting positrons.

  • Result: Collisions with electrons produce gamma rays, visualizing organ function activity with different colors for activity level.

7. Endoscopy

  • Description: Uses a scope to capture images or videos of internal organs.

  • Common Types: Includes colonoscopy, upper endoscopy, and laparoscopy.

8. Radionuclide Scanning

  • Technique: Uses radioactive tracers to examine organs and tissues.

The Chemical Level of Organization

  • Focus Areas:

    • Identify major chemical elements of the human body.

    • Describe structures of atoms, ions, molecules, free radicals, and compounds.

Chemical Elements

States of Matter

  • Matter exists in three states: solid, liquid, gas.

Main Chemical Elements in the Body (Table 2.1)

  • Major Elements:

    • Oxygen (O) - 65.0%

    • Carbon (C) - 18.5%

    • Hydrogen (H) - 9.5%

    • Nitrogen (N) - 3.2%

  • Lesser Elements:

    • Calcium (Ca) - 1.5%, Phosphorus (P) - 1.0%, etc.

  • Trace Elements:

    • Include Aluminum, Iodine, Zinc, etc.

Importance of Chemical Elements

  • Oxygen: Vital for water and organic molecule formation.

  • Carbon: Backbone of all organic molecules.

  • Hydrogen: Ionized form influences body fluid acidity.

  • Nitrogen: Constituent of proteins and nucleic acids.

  • Calcium: Essential for bones, blood clotting, hormone release, muscle contraction.

  • Phosphorus: Required for bone structure and nucleic acids.

  • Others: Necessary for enzyme activity, maintaining cellular functions, and electrical gradients in fluids.