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

Determine the functional brain activity, Determine the functional brain act...

Determine the functional brain activity PET is powerful means of assessing functional brain activity, although it does not directly measures neuronal events. Rather it indicate

Hirudinea - feeding and digestion in annelids, Hirudinea - Feeding and Dige...

Hirudinea - Feeding and Digestion in Annelids Hirudinea involves free living and ectoparasitic leeches. Leeches are blood suckers. The digestive system contains a preoral cham

Define the classification of proteins, Define the Classification of Protein...

Define the Classification of Proteins? Proteins vary widely in. their properties. We suggest you look up this unit once again now as the information about proteins and their pr

Digestive system - tongue, TONGU E - On the tongue 4 types of p...

TONGU E - On the tongue 4 types of papillae are present. (i) Filliform - Filliform papillae are most abundant and have no taste bunds. Filliform papillae

Deficiency diseases-thiamine deficiency (hypothiaminosis), Thiamine deficie...

Thiamine deficiency (hypothiaminosis) Thiamine deficiency is characterized by signs of nervous system. The primary  thiamine deficiency is not common in animals. However, seco

Describe what is respiration in dynamic auscultation, Describe what is Resp...

Describe what is Respiration in Dynamic Auscultation ? a) S 2 : Splitting of S 1 is audible during inspiration. b) Diastolic sounds and Ejection sounds: Inspiration augment

What is hemoglobin releasing hormone, In a red blood cell, which of the fol...

In a red blood cell, which of the following will lead to a reduction in the percentage of hemoglobin that has oxygen bound to it? A. A decrease in the amount of HbRH (Hemoglobi

What are the main water properties, What are the main water properties that...

What are the main water properties that make water special for life? The water properties that make water biologically significant are molecular polarity, thermal stability (el

Successive changes in animal life during hydrosere, Successive Changes in A...

Successive Changes in Animal Life during Hydrosere The successive changes in plant communities in the different seral communities of a hydrosere. The question arises, is ther

What are plant organs responsible for perception of light, What are plant o...

What are plant organs responsible for the perception of light variation? And what is the pigment responsible for this perception? The Leaves are mostly responsible for percepti

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