Question

Write short notes on excreation, respiration, digesion and about its organs

Answer 1

Excretion and its importance
The process by which animals get rid of themselves of waste products of nitrogenous by-products of metabolism is known as excretion. The organisms control osmotic pressure – the balance between inorganic ions and water- and maintain acid-base balance through this process. This process helps in promoting homeostasis, a process that helps maintain the stability that helps the organs or biological systems to survive.
Excretion is also done by green plants, which produce water as respiratory products. The carbon dioxide released by human during exhalation is utilised by green plants for the process of photosynthesis. Plants get rid of excess water by transpiration and guttation.
In general, plants contain vacuoles which save all other metabolic waste. They are in a leaf cell, which allows vacuoles to crystallize. We usually see the vacuoles get filled, the leaf drops. These are known as Excretophores. Saps and gums are also the types of excretion displayed by plants, which we see with our naked eye.
In human beings and animals, urine and feces are both the types of excretion. These wastes are important as it avoids inducing sickness. Sweating is also a type of excretion displayed by the human beings- it helps to eliminate liquid through the surface skin to reduce the heat of the body. As it is a cooling process, this is important, warm water would make the overall body temperature higher. Without this process, we would have suffered from dehydration.
The act of unusable or undigested material from a cell is called Egestion.
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 process 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.

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 about human respiration.
The human respiratory system consists of the following parts: 1. External nostrils – For the intake of air.
2. Nasal chamber – which is lined with hair and mucus to filter the air and remove dust and dirt.
3. Pharynx – It is a passage behind the nasal chamber and serves as the common passageway for both air and food.
4. Larynx – Also known as the sound box as it helps in the generation of sound and thus helps us in communicating.
5. Epiglottis – It is a flap like structure that covers the glottis and prevents the entry of food into the windpipe.
6. Trachea – It is a long tube passing through the mid thoracic cavity.
7. Bronchi – The trachea divides into left and right bronchi.
8. Bronchioles – Each bronchus is further divided into finer channels known as bronchioles
9. Alveoli – The bronchioles end up into the balloon like structures known as the alveoli
10. Lungs – We have a pair of lungs, which are sac like structures and covered by a double layered membrane known as pleura.
Digestion : Role of the Human Alimentary Canal
All living organisms require nutritional support for their survival. Food is one of the basic requirement to provide the energy to all living organisms. Food consists of three major biomolecules like Carbohydrates, proteins and fats. In addition to these biomolecules, water plays an important role to inhibit dehydration of the body. Biomolecules cannot be taken up by our body in the natural form. In the digestive system, complex food substance is converted into simpler food substance. This process of conversion of complex food molecules to simple absorbable molecules is called as digestion. Digestion is carried on by different types of mechanical and biochemical methods. The alimentary canal plays a critical role in the human digestive system.
Digestion and Alimentary Canal
The alimentary canal is also termed as the digestive tract. The alimentary canal starts from the mouth and ends in the anus. Alimentary canal consists of the following parts.
Human Alimentary Canal in digestion
Human Alimentary Canal
1. Mouth and Oral cavity
2. Oesophagus
3. Stomach
4. Small intestine
5. Large intestine
Mouth and oral cavity
Mouth is a first part of the alimentary canal. It consists of lips, cheeks, tongue and teeth. Teeth are used to masticate the food in order to increase the surface of the food for digestion. As a result, enzymes from the oral cavity act on the food effectively to increase the rate of digestion. Two sets of tooth form in the human life. These are as follows:
1. Milk teeth
2. Permanent teeth
Four different types of permanent teeth are present in the human beings.
1. Incisors
2. Canine
3. Premolars
4. Molars
The tongue is attached to the oral cavity floor. The papillae are present on the upper surface of the tongue which bears the taste buds.
Oesophagus
Oval cavity leads to the oesophagus. The oesophagus is a thin and long portion of the alimentary canal which opens into the pharynx. During swallowing the food, a flap-like structure prevents the food entry into the glottis. This flap like structure is called as epiglottis.
Stomach
Oesophagus leads into the stomach through the neck and the diaphragm. Oesophagus opening is regulated by a muscular sphincter into the stomach. The stomach consists of three parts. These are as follows:
1. Cardiac portion – It is a portion where oesophagus opens into the stomach.
2. Fundic portion – It is a region to store the food for long term digestion.
3. Pyloric portion – It is a region where stomach opens into the duodenum.
Pyloric sphincter is used to regulate the stomach opening into the duodenum.
mall intestine
Small intestine measures 6 m long and 2.5 cm thick. It contains the following three regions:
1. Duodenum – It is the first portion of the small intestine, which starts from the stomach.
2. Jejunum – It is used to absorb the nutrients from the digested food.
3. Ileum – It is also used to absorb the nutrients which are not absorbed by the jejunum.
Large intestine
The large intestine measures 1.5 m long. It is the last part of the alimentary canal. The main function of the large intestine is to absorb the water from solid wastes and store the waste materials. These waste materials are removed by defecation. The large intestine consists of five parts. These are as follows:
1. Cecum – It is used to absorb the digestive fluids.
2. Appendix – It is a vestigial organ. It does not have any specific function.
3. Colon – It is used to absorb the water from digested food. 4. Rectum – It is used to store the residual wastes.
5. Anus – It is used to remove the waste material to the outside of the body through sphincter contraction.