Role of the respiratory system in the excretion process in man & Respiration in plant
Human body contains a system that is responsible for the extractions of oxygen from the air , and then transfers it to the blood , then to the cells of the body , this system is called respiratory system , Respiratory system in man consists of many organs , each one is suited to perform its function , as follows :
Respiration in man
Nose or mouth : The air enters the body through the nose or the mouth , but it is preferable ( from the hygienic point of view ) for air to enter through the nose , because it is a warm passage , as it is lined with numerous blood capillaries , It is moist , as it secretes mucus , It serves as a filter , because it contains hairs which act as filters .
Pharynx : Air passes through it which is the common passageway for both air and food .
Larynx : The air enters the trachea through it and it is known as the voice box .
- Its wall contains a series of cartilage ¾ rings , to prevent the trachea from collapsing , thus maintaining an open passageway for air .
- The inner surface is lined with cilia which beat upwards , tending to create air and mucus currents to impede ( prevent ) the entry of small foreign bodies and move them to the pharynx where they may swallowed .
- It is divided at its lower end into two bronchi which divide and subdivide into progressively smaller and smaller bronchioles , each bronchiole finally opens into one of the many alveoli ( air sacs ) .
Lungs : Each animal including man possesses two lungs , a right lung and a left lung , They are characterized by having a large surface through which gas exchange occurs , Each lung consists of a group of alveoli that are connected to the bronchioles and the surrounding blood capillaries .
Functional suitability of alveoli
They are large in number reach to about 600 million alveolus per lung , to increase the respiration surface area , Their walls are considered as the actual respiratory surface , because :
- They are thin , so , increasing the speed of gas exchanging process .
- They are surrounded by a large network of blood capillaries whose blood receives oxygen from the alveolar air and from the bronchioles that are connected to them .
- They are moistened by water vapour which is necessary for dissolving CO2 and O2 , so , that the exchange of gases between the air of alveoli and the surrounding blood in the blood capillaries occurs .
Role of the respiratory system in the excretion process
The respiratory system in man plays an important role in the excretion of water in the form of water vapour , where man usually loses daily about 500 cm³ of water through his lungs out of 2500 cm³ of water that he loses daily , This is due to the evaporation of water that moistens the alveolar membranes and is necessary for dissolving oxygen and carbon dioxide .
Respiration in plant
Respiration process in plant is the process of getting the chemical energy stored in the organic substances ( glucose ) through a chain of reactions which includes the breaking down of carbon bonds of these substances to carry out the vital activities .
In most plants , each living cell is in a direct contact with the external environment , therefore the gaseous exchange is easy to occur , In this case oxygen diffuses inside , while CO2 is released outside the cell .
Types of respiration process in plant :
- Aerobic respiration : the release of energy occurs in the presence of oxygen .
- Anaerobic respiration : the release of energy occurs in the absence of oxygen .
Respiration in vascular plants
Oxygen reaches the cells through various passageways :
- The stomata of leaf : when they open , The air enters to the air chambers , and then diffuses through the intercellular spaces , spreading to various parts of the plant , so , the gas diffuses through the cell membranes and dissolves in the water of cell .
- The phloem passageway : some of oxygen is carried to the phloem passageway , dissolved in water and finally reaches the tissues of stem and root .
- The roots : oxygen enters the plant , soluble in water of the soil solution when it is absorbed by the root hairs or imbibed by the cell walls .
- The stomata of green plant stem , the lenticels or any cracks in the bark of woody stems : They act as an entrance for air .
Methods of CO2 expelling to outside ( that is produced from the respiration :
- By direct diffusion from the plant cells which are exposed directly to the external environment .
- For deep seated cells , gaseous exchange occurs by mutual diffusion of CO2 to the xylem vessel or the phloem tissue which passes CO2 in return to the stomata , then to the external atmosphere .
Relation between photosynthesis and respiration in plant
The plastids perform the photosynthesis process to produce glucose and oxygen , Glucose & oxygen move to the mitochondria to release the energy through respiration , CO2 and water that are produced from the respiration move to the plastids for performing the photosynthesis process .