Lower respiratory tract, Biology

Assignment Help:

Lower Respiratory Tract:

Trachea:

 

1053_Lower Respiratory Tract.png

Trachea or windpipe  is 12 cm long, 2.5 cm in diameter lying in front of the esophagus and  ends opposite the fourth dorsal vertebrae where it divides  into main bronchi.  It consists of a number of c-shaped rings of cartilage connected byfibrous tissues and having the opening of the C posteriorly. The hnction of the rings of cartilage is to keep trachea open  and prevent the collapse of the wall like those of the esophagus. It is lined with ciliated columnar epithelium and cells which secrete mucus.  

Bronchi and Bronchioles:

Trachea ends by  bifurcating into right and  left bronchi at the carina, the level of fourth dorsal vertebra. Each bronchus passes  to the corresponding lung. From each main bronchus smaller bronchi are given off, like branches of a tree, and the smallest bronchi is called bronchioles. The structure of  the bronchi is similar to that of the bronchi, but they  contain no cartilaginous loops, instead there are more muscle fibers. Mucus is secreted by  goblet cells interspersed between the ciliated cells and  by  sub-mucosal mucus-secreting glands. 

Each bronchioles terminate in an alveolar sac made up of number of air pockets wihc are lined with delicate layer of flattened epithelial cells and are surrounded by network of capillaries through the walls of which interchange of gasses takes place. Blood in the capillaries is brought by  the pulmonary artery from the right ventricle and drained into  the  left atrium through the pulmonary veins. Alveoli which number 300 millions  in adults are minute sacs that arise from the walls of the respiratory bronchioles and alveolar ducts. The alveolus is composed of a single layer of squamous epithelium and elastic basement membrane. These two layers together with the interstitium and the endothelial and basement layers of the adjacent capillary, from the alveolar-capillary membrane or interface. It is across this membrane diffusion of carbon dioxide and oxygen occurs. The structure of millions alveoli provides a large surface area for gaseous diffusion to occur. In  addition to this respiratory hnction the alveoli prevent  lung collapse by producting surfactant, a phospholipid that decreases surface tension and prevents intersititial fluid  from  transferring into the lung space.  


Related Discussions:- Lower respiratory tract

Codominance, explain the genotypes for each blood type and how this is an e...

explain the genotypes for each blood type and how this is an example of codominance. Blood type- A, AB, B, 0

Define the working of cyclomixer, Define the working of Cyclomixer? Thi...

Define the working of Cyclomixer? This is an electrical mixer used for mixing the contents of a test tube. The speed of the mixer can be adjusted to your requirement. This is a

How does the Cornea work, How does the Cornea work, I heard that it is like...

How does the Cornea work, I heard that it is like a motor, however i''m not too sure... because a motor is in vehicle and has piston, and the Cornea is in our eyes and... Well does

Determine the accession number for the related gene-locus, Please answer th...

Please answer the following two questions on Sequence X: 1) DNA sequence databases 1. What is the EMBL-Bank accession number for this sequence (use BLAST)? 2. Which gen

Alive and something that is a living organism, Is there a difference betwee...

Is there a difference between something that is alive and something that is a living organism?

Where is the patient most likely to experience, The most recent blood work ...

The most recent blood work of a patient with a diagnosis of acute myelogenous leukemia (AML) reveals thrombocytopenia. Where is the patient most likely to experience abnormal bleed

Specific considerations and applied aspects in dentistry, Specific consider...

Specific considerations and applied aspects in dentistry The dental chair and delivery system. The chair should be smooth and seamless. The greatest potential for cross contami

What are the lateral meristems, What are the lateral meristems? Where can t...

What are the lateral meristems? Where can they be found and which kind of plant growth do they promote? The Lateral or the secondary, meristems, are the cambium and the phellog

What best describes the amoebas division, What best describes the amoebas d...

What best describes the amoebas division?  (1) It is a Mode of asexual account in which a one parent is involved. The amoeba cell, which is unicellular, separates into two daug

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd