Lecture Slides - Cardiovascular system, Respiratory System and Neuromuscular system

MODULE: Human Life Sciences 1 (SESC 116)

Assessments Overview


Sections in the Course

  1. Respiratory System

  2. Cardiovascular System

  3. Neuromuscular System

Section 1: Respiratory System

Focus Areas

  • Major anatomical structures of the respiratory system and control of respiration.

  • Correct physiological terminology for ventilation, respiration, gas diffusion, and transport.

  • Conduct calculations related to respiratory physiology.

Respiratory System Overview

  • Composed of airways, lungs, and respiratory muscles.

  • Key functions:

    • Gas exchange between the external environment and the body.

    • Regulation of oxygen and carbon dioxide levels in blood.

    • Maintenance of blood acid-base balance.

    • Humidification and cleaning of air.

Anatomical Structures

  • Major components:

    • Pharynx, Nasal Cavity, Nose, Epiglottis, Oral Cavity, Larynx, Esophagus.

    • Airways: Trachea, Bronchi (Right and Left), Bronchioles, Alveoli.

Breathing Terminology

  • Inhalation (Inspiration): Air flow from atmosphere into lungs with diaphragm contraction.

  • Exhalation (Expiration): Air flow from lungs to atmosphere with diaphragm relaxation.

Types of Respiration

  • External (Pulmonary) Respiration: Gas exchange between atmosphere and blood.

  • Internal Respiration: Gas exchange between blood and body cells.

Thoracic Cavity

  • Houses the lungs and heart; composed of ribs, spine, and sternum.

  • Muscles:

    • Internal/External intercostals, Sternocleidomastoid, Scalene, and various abdominal muscles (Rectus Abdominis, Transverse Abdominis).

Lungs Overview

  • Two cone-shaped organs (Right lung: 3 lobes; Left lung: 2 lobes) containing alveoli for gas exchange.

  • Right lung accounts for ~55% of total lung volume due to left heart positioning.

  • Average weight of a lung: ~1 kg in a 70-kg adult.

Pleura and Pleural Cavity

  • Pleura: Thin membranes enclosing the lungs:

    • Parietal Pleura: Lines thoracic walls.

    • Visceral Pleura: Fused to lung surface.

  • Pleural Cavity: Contains ~10 mL of pleural fluid for lubrication.

Conducting Zone

  • Air passages facilitating air transport; includes nose, nasal cavity, mouth, pharynx, larynx, trachea, and bronchi.

  • Functions: Conditioning and cleaning air to prevent respiratory tract damage.

Trachea

  • Windpipe: A semicircular tube (2.5 cm diameter, 12 cm length) supported by cartilage rings, lined with ciliated epithelium and mucus.

  • Divides into Right/Left Bronchi.

Bronchial Tree

  • A divides network leading to gas exchange areas; approximately 23 generations.

a. Conducting Zone (first 16 generations)

b. Respiratory Zone (last 7 generations).

Respiratory Zone

  • Site of gas exchange; includes respiratory bronchioles, alveolar ducts, and alveoli.

Alveolus: ~0.25 mm in diameter, crucial for O2 and CO2 exchange.

Respiratory Membrane

  • Composed of Type I and Type II alveolar cells, pulmonary capillaries, and fused basement membranes facilitating gas exchange.

Factors Affecting Gas Diffusion

  1. Gas Solubility: Carbon dioxide is more soluble in blood than oxygen (20x).

  2. Pressure Gradient: Higher difference results in faster diffusion.

  3. Surface Area: Larger surface area enhances efficiency of gas exchange; lungs provide ~65-70 m².

  4. Diffusion Space: Thin alveolar membranes (~0.5 µm) optimize rapid gas exchange.

Hemodynamics of Breathing

  • Ventilation Mechanics:

    • Inspiration involves diaphragm contraction, increasing lung capacity and decreasing pressure.

    • Expiration is mostly passive, relying on lung elasticity.

Muscle Involvement During Exercise

  • During exercise, accessory muscles assist breathing:

    • Involved muscles include sternocleidomastoid, scalenes, external intercostals for inspiration; internal intercostals and abdominal muscles for active expiration.

Cardiovascular System Dynamics

  • Understanding of heart function, cardio-respiratory interdependence, and hemodynamic calculations required for exam preparation.