3.Human Physiology
3.2 Respiration
Respiration
Dr V Malathi
Respiration refers to the movement of air into and out of the lungs . This process comprises of
- Inspiration is the process that causes air to enter the lungs, and
- Expiration is the process that causes air to leave the lungs
Functions of the Respiratory system are :
- To provides oxygen to body tissues for cellular respiration,
- Removal of the waste product carbon dioxide,
- To maintain acid–base balance .
A respiratory cycle is one sequence of inspiration and expiration .
Respiratory rates vary based on age.
The normal resting respiratory rate is as follows :
- for adults is 10–20 breaths per minute .
- For Children less than one year is 30–60 breaths per minute,
- For children by the age is usually 18–30 .
- By adolescence, the respiratory rate is 12–18 breaths per minute (Much similar to adults ).
- The normal respiratory rates decreases from birth to adolescence and often increase slightly over the age of sixty-five.
The Respiratory System
“Major Respiratory Organs” by OpenStax College via Wikimedia commons is licensed under CC BY 3.0
Nose and Nasal Cavity
The upper respiratory tract begins with the nose and ends with the larynx. The nose externally extends from the frontal bone to the maxilla. The nose consists of a central cartilage (the septum) with two lateral processes. The openings to the nose are the nares.
The nares are lined with coarse hairs to aid in the filtration of particulate matter.The visible nose is actually the entryway into the nasal cavity, where the major functions of the nose occur. The area immediately inside the nares contains a large number of sebaceous glands, sweat glands, and hair follicles.
The olfactory epithelium found in the nasal cavity is used to detect odors .The nasal cavity is divided into the right and left sides by the nasal septum.The roof of the nasal cavity consists of parts of the ethmoid and sphenoid bones.The of the nasal cavity floor is called the palate which forms the roof of the mouth. The palate is separated into the hard and soft palate.
The anterior hard palate is formed from part of the palatine bone. The posterior soft palate called the uvula does not contain bone. The uvula moves up during swallowing to close off the nasal cavity, thus preventing material from entering the mouth.
Within the bones surrounding the nasal cavity are hollow spaces called paranasal sinuses , which function to make the skull lighter as well as moisten and warm incoming air.
The nasal cavity opens into the nasopharynx.
Pharynx (Throat)
The pharynx connects the nasal passage to the larynx in the throat. The pharynx has three distinct areas namely, the nasopharynx, the oropharynx, and the laryngopharynx.
The pharyngeal tonsils are located at the top of nasopharynx. The pharyngeal tonsils contains rich supply of lympocytes and ciliated epithelium which traps and destroys the invading pathogens .
The pharyngeal tonsils are large in children, but tend to