F

CLASS-X EPISODE- STATE SYLLABUS

RESPIRATION

(BRACHIAL & PULMONARY)

Have you seen an aquarium? Did you observe the fish?When you observe fish in an aquarium you will find that the mouth of fish is opening and closing continuously. You will also observe that on the sides of the head below the mouth a cover like structure is opening and closing. Do you know that GILLS are present below this cover?

Fish respire with the help of gills. By opening and closing of the mouth water flows from the oral cavity and flows constantly over the gills. The water flows out through external gill apertures. The gills are richly supplied with blood vessels. As the water flows over gills, oxygen is absorbed from water and CO2 is expelled into the water flowing out of gills. Thus the exchange of gases takes place.

Show an aquarium live Let us now examine the structures present in respiratory system of fish.It consists of . . . . . . . . .

a) Internal Brachial aperturesb) Brachial pouches or Gill Pouchesc) External brachial pouches

The internal brachial pouches are connected to the pharynx internally and open to the outside by the external brachial apertures. The Gill pouches possess the gills. The gills are covered by a mucous membrane. There are several horizontal

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leaf like folds in Gills called as GILL LAMELLAE. They are richly supplied with blood vessels.

PROCESS OF RESPIRATION: - Animate1) Fish opens its mouth.2) The floor of oral cavity is lowered.3) Water enters oral cavity.4) Fish closes mouth.5) Floor of oral cavity rises.6) Water enters the gill pouches through the internal brachial apertures.7) Lamella bathed in water perform the exchange of O2 and CO2 8) The water from gill pouches passes out through the external brachial

apertures.

This process is continuous. The fish opens and closes the mouth to draw water into oral cavity.

Animate process of respiration

The image is a schematic diagram of the process of respiration in fish

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The external brachial aperture is visible in cartilaginous fish or the ELASMOBRANCHS. In fish belonging to the category of bony fishes or the TELEOSTI the openings are covered by a bone called OPERCULUM.

What are the respireatory organs in other vertebrates?The organs of respiration in majority of vertebrates other than fish are LUNGS. The respiration through lungs is called as PULMONARY RESPIRATION.

The pulmonary respiration is best understood by studying the Human respiratory system.

We will examine the structure first and then the process of respiration will be examined.

Respiratory Organs in Man

The respiratory organs in man are . . . . . . . . 1) Nose or Nostrils2) Nasal cavity3) Pharynx4) Larynx5) Trachea6) Bronchi7) Bronchioles and alveoli8) Lungs

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a) Nose or Nostrils: - Human beings respire through nose or nostrils. The external part of the nose bears two NOSTRILS separated by a Septum.

The nostril and equipped with cells sensory to smell. They can detect different odour. Further entry of large particles is prevented by the presence of hairs present in the nostrils.

B) Nasal Passage: - The nostrils open into nasal passage or chambers. These passages are lined with glands which secrete mucus. The air passing through the passages is

a) Warmedb) Added with moisturec) Cleaned by mucous which entraps the dust and other harmful particles.

c) Pharynx or Throat: - The pharynx lies behind the mouth. The nasal cavity opens into the pharynx. This opening is common for both passage of air and food. Below the pharynx these are two passages one for air and one for food.When food is passing the common passage into pharynx, it is prevented from entering the air passage and is closed by a flap like cartilaginous structure called epiglottis. Epiglottis covers the slit called Glottis present at the beginning of wind pipe.

d) Larynx or Voice Box: - The pharynx opens into LARYNX. The larynx is popularly called as ADAM’ SAPPLE. The larynx is a hollow cartilaginous structure. It opens into trachea. There are two ligamentous folds in larynx called as VOCAL CORDS. The vocal cords

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