Mammalian lungs - respiration, Biology

Mammalian Lungs - Respiration

In this we will study mainly mammalian lungs as it is the best representative of a respiratory surface adapted for terrestrial respiration. For this purpose, human lung can be taken as a model as shown in Figure. When we breathe, the air enters the wind pipe or trachea which is divided into right and left bronchi. These in turn branch repeatedly 'forming bronchioles. The fine branches of the bronchioles lead into alveolar sacs, which are clusters of minute sacs, whose diameter ranges between 150 to 300 micron or micrometer. The alveoli have thin walls and capillaries from the pulmonary artery extensively occupy the vascular side of the alveoli. A pair of human lungs contain about 300 million alveoli and the total surface area is about 70 meter square. This area is nearly equal to a tennis court.

684_Mammalian Lungs - Respiration.png

Figure: In humans and other mammals, air passages Include nostrils, nasal cavity (and mouth), pharynx, larynx, trachea, bronchi, and bronchioles. The bronchioles terminate in numerous Mind alveoli. The spongy lungs are subdivided into lobes, with three in the right long and two in the left lung. The muscular, shelf-like diaphragm seals the thoracic cavity off from the abdominal cavity below.

Gas exchange takes place only in the alveoli. Trachea, bronchi and their branches are only connecting tubes. When we breathe out, these tubes are filled with used air from the lungs and when we breathe in again this used air is pushed back into the lungs first, before the fresh air enters. The volume of air in the passage thus reduces the volume of fresh air that can enter the lungs. Therefore, this space is called anatomical dead space. The dead space volume is 150 cm3. The volume of air inhaled in one breath is called the tidal volume and for a normal man at rest it is about 500 cm3. Therefore, only 350 cm3 (500 - 150 = 350) of fresh air reaches the alveoli. In exercise the dead space volume is not significant. For example, a man may breathe 3000 cm3 of air in a single breath, in that case 150 cm3 is hardly significant.

Posted Date: 1/15/2013 7:10:37 AM | Location : United States







Related Discussions:- Mammalian lungs - respiration, Assignment Help, Ask Question on Mammalian lungs - respiration, Get Answer, Expert's Help, Mammalian lungs - respiration Discussions

Write discussion on Mammalian lungs - respiration
Your posts are moderated
Related Questions
Phimosis Phimosis may be congenital or acquired. The foreskin in young infants cannot be retracted, because at that gge it is adherent to the underlying glans. Wlen an attemp

Which one of the following has its own DNA? 1. Mitochondria 2. Dictyosome 3. Lysosome 4. Peroxisome Mitochondria

Transplantation - It is implanting of a living or preserved tissue or organ from one site to another side in the same individual or from one individual called donor to recip

locomotion in parameceum

Q. What are the procedures of the photochemical stage of the photosynthesis process? Photolysis of water, with liberation of molecular photophosphorylation and oxygen of ADP, w

Venipuncture : patient should be seated or supine for at least 20 minutes before sampling. An arm with an inserted intravenous line should be avoided. The median cubi

Define Corneal Scar - Micronutrient Deficiencies? The corneal ulcer, on healing, leaves a white scar, which may vary in size depending upon the size of the ulcer. When the scar

Which of the following structures in a vertebrate with a four-chambered heart would have blood with the highest oxygen concentration? And why?

Pleural Biopsy Pleural biopsy is one of the diagnostic procedure which may  cause lot of anxiety in  the patient. Procedure Pleural biopsies may be preformed surg

Anatomy: Anatomy (from Greek words anatomia which means separate and temnein which means to cut open) is a branch of biology and which deals with the study of internal organizatio