Question

explain me this briefly

Answer 1

Chewing, in which food is mixed with salivabegins the process of digestion. This produces a bolus which can be swallowed down the esophagus and into the stomach. Here it is mixed with gastric juice until it passes into the duodenum where it is mixed with a number of enzymes produced by the pancreas. Saliva also contains a catalyticenzyme called amylase which starts to act on food in the mouth. Another digestive enzymecalled lingual lipase is secreted by some of the lingual papillae on the tongue and also from serous glands in the main salivary glands. Digestion is helped by the masticationof food by the teeth and also by the muscular actions of peristalsis and segmentation contractions. Gastric juice in the stomach is essential for the continuation of digestion as is the production of mucus in the stomach.

Peristalsis is the rhythmic contraction of muscles that begins in the esophagus and continues along the wall of the stomach and the rest of the gastrointestinal tract. This initially results in the production of chymewhich when fully broken down in the small intestine is absorbed as chyle into the lymphatic system. Most of the digestion of food takes place in the small intestine. Water and some minerals are reabsorbed back into the blood in the colon of the large intestine. The waste products of digestion (feces) are defecated from the anus via the rectum.

Answer 2

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The Human Respiratory System

The Human respiratory system is mainly involved in supporting the exchange of gases in our body.



Respiration is one of the metabolic processes which play an essential role in all living organisms. When we breathe, we inhale oxygen and exhale carbon dioxide. The so-called exchange of gases is necessary for respiration and which can be considered as a chemical process.

Every organism, from an individual bacteria cell to a mighty blue whale, undergoes respiration.

But, before we discuss respiration in humans, let us first look at the respiratory organs of other organisms. This would give us a better idea of how the human respiratory system is more advanced than the others.



Human Respiratory System

Breathing is the first step in respiration for almost all organisms. The inhale and exhale of gas and its mechanism depends on the environment in which the organisms survive.

For instance, the lower organisms like the unicellular take up oxygen and release carbon dioxide by the process of diffusion across their membrane. Annelids like earthworms have a moist cuticle which helps them in gaseous exchange. Respiration in fish and other aquatic organisms have special organs called gills, which help them in respiration. Most of the higher organisms possess a pair of lungs for breathing. The humans have a well developed respiratory system. Let us take a look at human respiration.

The human respiratory system consists of the following parts:

External nostrils – For the intake of air.

Nasal chamber – which is lined with hair and mucus to filter the air and remove dust and dirt.

Pharynx – It is a passage behind the nasal chamber and serves as the common passageway for both air and food.

Larynx – Also known as the sound box as it helps in the generation of sound and thus helps us in communicating.

Epiglottis – It is a flap-like structure that covers the glottis and prevents the entry of food into the windpipe.

Trachea – It is a long tube passing through the mid-thoracic cavity.

Bronchi – The trachea divides into left and right bronchi.

Bronchioles – Each bronchus is further  divided into finer channels known as bronchioles

Alveoli – The bronchioles end up into the balloon-like structures known as the alveoli

Lungs – We have a pair of lungs, which are sac-like structures and covered by a double-layered membrane known as pleura.

For more detailed information about the human respiratory system, visit Byju’s