---
title: Zoology - Breathing and Respiration
disqus: '5514'
description: Notes of Zoology coaching. Question answers of chapter 5.
---

# Respiration and Breathing
All organisms require energy for sustaining life activities. Respiration is an energy releasing process. It is defined as biological oxidation in which stored food in the presence of oxygen is broken down step-by-step to release metabolically usable energy, giving out Carbon Di Oxide and water vapour as by-products. It goes on in all living cells at every moment of their existence as living entities. Actually respiration involves the reactions of carbon dioxide the oxidation and the mechanism of transportation of oxygen and carbon dioxide. In this chapter a discussion has been made about the human respiratory system, Respiratory mechanism and some related troubles.

## What is the vestibule?
The most anterior part of nasal cavity called vestibule.

## What is Choana? (Plural: Chonae)
Chonae are the posterior opening of nasal cavity.

## What is pulmonary root?
Bronchus, artery, vein and lymph vessel altogether surrounded by dense connective tissue and form a structure to hang the lungs in the chest cavity. This structure is called pulmonary root.

## What is branchial tree?
Each bronchus after entering into the lungs divides into smaller and smaller bronchioles like a tree branches into thinner branches.The structure from the bronchus to the alveolus looks like a branched tree, hence called branchial tree or pulmonary tree or respiratory tree.

## What is respiration?
Respiration is a complex process which involves inhaling, transport of oxygen and carbon dioxide, exhaling in production of energy by the oxidation of food.

## Write down the function of epiglottis.
Epiglottis is a leaf shaped flap of cartilage located on the top of larynx area. The main function of epiglottis is to seal of the wind pipe during eating so that food is not accidentally inhaled The glottis move and performs its vital functions only when we sold the food or drink or something.

## What is alveolus?
Alveolus is the functional and structural unit of lungs that permits gas exchange between the air and the blood capillaries of the lungs.

## Describe the breathing mechanism of human being.

The process that moves air in and out of the lungs so that oxygen can be exchange for carbon dioxide is called breathing or ventilation. The mechanism of breathing in human impulse to events: Inspiration and expiration. Two types of muscles are involved in breathing mechanism
1. Phrenic muscle of diaphragm
2. Intercostal muscle in between the ribs
### Inspiration
Inspiration is an active process. During inspiration the intercostal muscles contract so that the ribs swing outwards and upwards to increase the diameter of the thorax. At the same time due to the contraction of phrenic muscle the diaphragm is flattened. The combined effect increases the volume on the thoracic cavity and thus air pressure inside the lungs decreases. The air is drawn from high-pressure area (i.e outside area) to the low pressure area (i.e inside the lungs) which is called inspiration. In lungs, exchange of gases between air and blood stream takes place through the epithelial tissue of alveoli.


### Expiration
It is a passive process. During expiration the phrenic muscles the diaphragm and intercostal muscles relax. As a result ribs fall, sternum sinks and the diaphragm is upwards.Air from lungs expelled out from the lungs through the trachea and the nasal cavity which causes expiration.