Mammalian lungs - respiration, Biology

Assignment Help:

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.


Related Discussions:- Mammalian lungs - respiration

Functions based on management principles, FUNCTIONS BASED ON MANAGEMENT PRI...

FUNCTIONS BASED ON MANAGEMENT PRINCIPLES: Planning: The objectives of nursing unit should be achieved through planning, good coordination and supervision. While planning nur

Why physical activity is important for weight loss, Why Physical Activity i...

Why Physical Activity is important for weight loss? You are already aware that exercise plays an important role in initiating and sustaining weight loss along with dietary and

Illustrate about the complex partial seizures, State about the Complex part...

State about the Complex partial seizures Complex partial seizures, another type of focal seizure, originate most commonly in the temporal lobe. Complex partial seizures are cha

Illustrate stage of cellular respiration, Q. What is the stage of cellular ...

Q. What is the stage of cellular respiration during which carbon dioxide is liberated? In aerobic cellular respiration the release of carbon dioxide happens in the transformati

Simple precautions to prevent injuries, When resheathing needles, simple pr...

When resheathing needles, simple precautions to prevent injuries are to: 1. use only one hand to scoop the cap 2. hold the sheath with a hemostat (suggested but will require

Explain why this drug would eventualy kill a person, Dinitrophenol, DNP, wa...

Dinitrophenol, DNP, was prescribed in low doses in the 1940's to help obese patients lose weight. It's use for this purpose was discontinued when several users died. DNP makes the

Marine biomes, The marine biomes consist of the earth's oceans and its asso...

The marine biomes consist of the earth's oceans and its associated areas like the shorelines, islands, reefs and estuaries. The marine waters contain about 3.5 percent salt, mostly

Biosynthesis of hemes and chlorophylls, In animals, some of bacteria and fu...

In animals, some of bacteria and fungi, and the first step in tetrapyrrole synthesis is the condensation of the amino acid glycine with succinyl  CoA (an intermediate  of the citri

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