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

Find the magnitude and direction of the net electric force, Three point cha...

Three point charges are located at the corners of an equilateral triangle as in the figure below. Find the magnitude and direction of the net electric force on the 1.40 µC charge.

How is the nervous system of nematodes organized, Q. How is the nervous sys...

Q. How is the nervous system of nematodes organized? Where are the neural chords located in their body? Roundworms have a ganglial nervous system with an anterior neural ring r

Social determinants of health - unemployment, Social Determinants of Health...

Social Determinants of Health - Unemployment That unemployment gives rise to social insecurity and psychological stress is well recognised. Fears and uncertainties are known t

Extended point within pulp chamber-endodontics principles, Extended point w...

Extended point within pulp chamber: Gripping action: -    Steglitz forceps or pin pilers. -    Access cavity flooded with chloroform to dissolve the sealer. -    Grasp the

Determine about the sense of contrast, Determine about the Sense of  Contr...

Determine about the Sense of  Contrast It is  the ability to  perceive  slight changes  in  luminance between  regions which  are not  separated by  definite borders. This  is

Describe a health issue or disease, Describe a health issue or disease and ...

Describe a health issue or disease and recommend an intervention (you may utilize the health issue . Justify the intervention level (primary, secondary and tertiary) and setting ch

Epistasis, EPISTASIS Epistasis is the phenomenon of masking or suppress...

EPISTASIS Epistasis is the phenomenon of masking or suppressing the expression of a gene by another non allelic gene. The gene which suppresses the expression of a non allelic

Explain about the adequate intake (ai), Explain about the Adequate Intake (...

Explain about the Adequate Intake (AI)? If sufficient data are not available to establish an EAR and hence RDA, the AI is derived instead. The AI is derived from observations o

Haptotaxis - modes of cell movement, Haptotaxis - Modes of Cell Movement ...

Haptotaxis - Modes of Cell Movement Haptotaxis considers to the directed movement of cells in response to a concentration gradient of an adhesive molecule that might be presen

Phase (different interference) contrast microscopy, Phase (different interf...

Phase (different interference) Contrast microscopy: Living cells are mostly   transparent. For viewing under ordinary light microscope, therefore, live cells must be stained wi

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