This document discusses the structure and functions of the trachea and lungs. It describes the trachea as a tube made of C-shaped cartilage rings that branches into the two bronchi and lungs. Each lung is cone-shaped with lobes and is smaller on the left side to make room for the heart. The lungs contain alveoli for gas exchange and have ciliated cells and mucus in the trachea to filter air before it reaches the lungs. The main functions are gas exchange in the lungs and air filtration in the trachea.

1. Mr.Ramesh pawar .Msc(Zoology)

2. Physiology of trachea and lungs

4. INTRODUCTION
 Trachea (or windpipe ) is a 10-11cm long continous pathway
from the larynx, which extends downwards up to the 5th
thoracic vertebra.
 Here it splits at the carina into right and left bronchi, entering
the respective lungs.
 It lies in the median plane in front of the oesophagus.

5. STRUCTURE
 Trachea is composed of 16-20 C-shaped (posteriorly incomplete )
rings of hyaline cartilage lying one above the other.
 Connective tissues and involuntary muscles (trachealis muscle) join
the cartilages and form the posterior wall where they are incomplete.
 The trachea cartilages are covered by the following three tissue
layers:

6. 1) Outer Layer: This layer is made up of fibrous and elastic
tissues enclosing the cartilages.
2) Middle Layer: This layer is made up of cartilages and bands of
smooth muscles winding around the trachea helically. This layer
also contains areolar tissues containing blood,lymph vessels, and
autonomic nerves.
3) Inner Layer: This layer is made up of ciliated columnar
epithelium, containing mucus-secreting goblet cells.

7. FUNCTIONS
 The main function of trachea
 Support and patency
 Mucociliary escalator
 Cough reflex
 Warming,humidifying and filtering of air.

8. Lungs

9. INTRODUCTION
 Lungs are one of the important respiratory system that is
helpful in exchange of gases,like carbondioxde and oxygen.
 Lungs are present in the thoracic cavity as two cone-shaped
lobes seperated by the heart and other structures of
mediastinum.
 The size of left lung is smaller than the right lung due to the
space occupied by the heart in the thoracic cavity.

10.  The right lung is thicker, broader, and shorter than the left
lung because the diaphragm on the right side is higher to
accommodate the liver inferior to it.

11. STRUCTURE
 The lungs are located in the chest on either side of the heart
in the rib cage.
 They are conical in shape with a narrow rounded apex at the
top, and a broad concave base that rests on the convex
surface of the diaphragm.
 The right lung has both more lobes and segments than the
left.
 The left lung is divided into two lobes,an upper and a lower
lobe, by the oblique fissure,which extends from the costal to
the mediastinal surface of the lung both above and below the
hilum.

12. FUNCTIONS
 The major functions of the lungs is gas exchange between the
lungs and the blood.
 It also helps in the protection against, some of the viruses and
bacteria.
 Lungs also helps in regulating the acid-base balance.
 It also helps in regulating the blood volume and blood
pressure.