Respiratory System Overview

Study Notes

Overview

The respiratory system is a complex biological process that brings oxygen into the body and removes carbon dioxide. It is essential for the survival of all living organisms.

Functions

Brings oxygen into the body
Removes carbon dioxide from the body
Regulates pH levels by removing hydrogen ions

Organs Involved

Nose and mouth (entry points for oxygen)
Trachea (windpipe)
Bronchi (airways)
Lungs (gas exchange)
Diaphragm (muscle that separates chest cavity from abdominal cavity)
Intercostal muscles (muscles between ribs that help expand chest cavity)

Process of Breathing

Inhalation:
- Diaphragm contracts and flattens
- Intercostal muscles contract and ribs move outward
- Chest cavity expands and air enters nostrils or mouth
- Air passes through trachea and into bronchi
- Air enters lungs and oxygen diffuses into bloodstream
Exhalation:
- Diaphragm relaxes and rises
- Intercostal muscles relax and ribs move inward
- Chest cavity decreases in size and air is pushed out of lungs
- Air passes out of nostrils or mouth

Gas Exchange

Occurs in alveoli (small air sacs in lungs)
Oxygen diffuses from alveoli into bloodstream
Carbon dioxide diffuses from bloodstream into alveoli
Oxygen-rich blood transported to heart and pumped to body
Carbon dioxide-rich blood transported to heart and pumped to lungs for exhalation

Respiratory System Overview

The respiratory system is a complex biological process that brings oxygen into the body and removes carbon dioxide, essential for the survival of all living organisms.

Functions

Brings oxygen into the body through inhalation
Removes carbon dioxide from the body through exhalation
Regulates pH levels by removing hydrogen ions

Organs Involved

Nose and mouth: entry points for oxygen
Trachea: windpipe that passes air into bronchi
Bronchi: airways that branch into lungs
Lungs: site of gas exchange, where oxygen is absorbed and carbon dioxide is removed
Diaphragm: muscle that separates chest cavity from abdominal cavity, contracts and relaxes to facilitate breathing
Intercostal muscles: muscles between ribs that help expand chest cavity during inhalation

Breathing Process

Inhalation: diaphragm contracts and flattens, intercostal muscles contract, and chest cavity expands, allowing air to enter nostrils or mouth and pass into lungs
Exhalation: diaphragm relaxes and rises, intercostal muscles relax, and chest cavity decreases in size, pushing air out of lungs

Gas Exchange

Occurs in alveoli, small air sacs in lungs
Oxygen diffuses from alveoli into bloodstream
Carbon dioxide diffuses from bloodstream into alveoli
Oxygen-rich blood is transported to heart and pumped to body
Carbon dioxide-rich blood is transported to heart and pumped to lungs for exhalation

Lungs Structure

Protected by the rib cage in the thoracic cavity
Consist of 2 lungs, each divided into lobes (right lung: 3 lobes, left lung: 2 lobes)
Composed of alveoli, bronchi, bronchioles, and pleura

Alveoli

Tiny air sacs where gas exchange occurs
Responsible for exchanging oxygen and carbon dioxide between the lungs and bloodstream

Bronchi and Bronchioles

Airways that branch into smaller tubes (bronchi) and lead to alveoli (bronchioles)
Enable air to reach the alveoli for gas exchange

Pleura

Double-layered membrane that surrounds the lungs
Protects the lungs and allows for expansion and contraction

Gas Exchange

Occurs in the alveoli, where oxygen diffuses into the bloodstream and carbon dioxide diffuses out
Factors affecting gas exchange:
- Surface area: larger surface area increases gas exchange
- Thickness: thinner membrane increases gas exchange
- Partial pressure: difference in pressure between oxygen and carbon dioxide

Oxygenation

Oxygen diffuses from the alveoli into the pulmonary capillaries
Bound to hemoglobin in red blood cells, forming oxyhemoglobin
Oxygen-rich blood is transported to the heart and then to the body

Breathing Process

Involves inspiration and expiration
Inspiration:
- Diaphragm contracts
- Rib cage expands
- Air enters the lungs
Expiration:
- Diaphragm relaxes
- Rib cage descends
- Air leaves the lungs

Respiratory Control

Controlled by the nervous system
Brainstem: regulates automatic breathing
Voluntary control: can override automatic breathing

Respiratory Muscles

Diaphragm:
- Primary muscle of inspiration
- Contracts and relaxes to change the volume of the thoracic cavity
Intercostal muscles:
- Assist the diaphragm in expanding the thoracic cavity
- Located between the ribs
Accessory muscles:
- Used during forced breathing or heavy exercise
- Include muscles of the neck, back, and abdomen