Anatomy ePortfolio - Lecture Content: Unit Three

Figure

20.4.1: Inspiration and Expiration. During inspiration, the diaphragm and external intercostal muscles contract, expanding the volume in the thoracic cavity, creating a pressure gradient with lower air pressure in the lungs that draws air in. During expiration, the diaphragm and external intercostal muscles relax, reducing the volume in the thoracic cavity and reversing the pressure gradient with higher air pressure in the lungs that forces air out. (Image credit: "Inspiration and Expiration" by OpenStax is licensed under CC BY 3.0)

Respiratory System Overview

Link to my Quizlet with all the terms.

Compare and contrast the structure and function of the wall structure of the elements of the bronchial tree, including the roles played by the epithelium, cartilage, and smooth muscle.

Trachea

Epithelium: Ciliated pseudo-stratified columnar epithelium.

Cartilage: C-shaped rings of hyaline cartilage provide structural support to keep the airway open.

Smooth Muscle: Minimal, allowing some flexibility but limited control over airway diameter.

Bronchi

Epithelium: Ciliated pseudo-stratified columnar epithelium.

Cartilage: Irregular plates replace the C-rings, allowing more flexibility.

Smooth Muscle: More than in the trachea, some control of airway constriction or dilation.

Bronchioles

Epithelium: Transition to simple columnar or cuboidal epithelium.

Cartilage: Absent, making them more flexible.

Smooth Muscle: Lots, plays a critical role in regulating airflow through bronchoconstriction or dilation.

Alveoli

Epithelium: Simple squamous epithelium, thin for gas exchange.

Cartilage: None

Smooth Muscle: Little to none.

-Cartilage Decreases down the tree, as airways become smaller. Smooth muscle Increases, allowing for more control over airflow. Epithelium transitions from thick to thin for efficient gas exchange.

Describe the CH and FX of the alveolus and the mechanism of gas exchange.

Structure: Tiny, balloon-like air sacs with thin walls made of simple squamous epithelium, with network of blood vessels for gas exchange. They also have elastic fibers for expansion during breathing, and surfactant cells (type II alveolar cells) to help lubricate, prevent collapse, and reduce surface tension.They have a large surface area (150 million alveoli in each lung) to maximize gas exchange as well.

Functions: Facilitate gas exchange (oxygen and carbon dioxide) between air and blood, and maintain efficient oxygen delivery and carbon dioxide removal.

Mechanism of Gas Exchange:

Type I alveolar cells

Diffusion: Oxygen moves from high concentration in alveolar air to low concentration in blood, while carbon dioxide diffuses in the opposite direction. Gas Exchange = Respiration
1. oxygen enters RBC in capillaries by simple diffusion (low concentration of oxygen in RBC; higher concentration of oxygen in air we inhale)
2. O2 moves through five sets of PM to bind to hemoglobin inside RBC

-The thin walls of alveoli and capillaries (respiratory membrane) allow rapid gas exchange.

This process ensures oxygen enters the bloodstream for transport to tissues and removes carbon dioxide as a waste product.