Short half-life corresponds to high reactivity. The one nanosecond half-life of the hydroxyl radical indicates that it is so reactive that it reacts with the first molecule it bumps into. Ascorbate forms H2O2 on autoxidation direct combination with oxygen. Lipid peroxidation of polyunsaturated fatty acids exposed to oxygen leads to rancidity in foods.
The human respiratory system consists of a pair of lungs and a series of air passages leading to the lungs. The entire respiratory tract passage consists of the nose, pharynx, larynx, trachea, bronchi, and bronchioles.
Air enters the nose through the nostrils. When air passes through the nose, it is warmed, moistened and filtered. The hairs present in the nose filter out particles in the incoming air.
The air is moistened by the mucus present in the nose, and it is warmed by the blood flowing through the capillaries in the nose. The respiratory tract from the nose to the bronchioles is lined by mucous membranes and cilia. The mucus and cilia act as additional filters.
Behind the nose lies the pharynx throat. There are two passages here—one for food and the other for air. The air passes from the pharynx to the larynx, or the voice box. The opening leading to the larynx is called glottis. It is protected by a lid called epiglottis, which prevents food from entering the passage to the lungs.
From the larynx the air goes to the trachea, or the windpipe. The trachea is about 11 cm long. It is guarded by C-shaped cartilage rings, which prevent the trachea from collapsing.
The trachea divides into two tubes called bronchi.
Each bronchus divides and branches out in the form of thinner tubes called bronchioles. The bronchioles enter the lungs and divide further into finer branches called alveolar ducts.
These open into extremely thin-walled, grape-shaped air sacs called alveoli. Each alveolus is covered by a web of blood capillaries. The lungs are a pair of spongy organs lying in the chest cavity formed by the ribs.
The actual exchange of gases between the air and the body takes place in the capillary-covered alveoli inside the lungs. Here, oxygen from the air in the alveoli goes into the blood, and the carbon dioxide in the blood goes out.
The oxygen binds to the haemoglobin molecules present in the red blood corpuscles and is taken to different parts of the body. The total surface area through which the exchange of gases can take place increases because of the millions of alveoli in the lungs.
Their total surface area can be about a hundred times that of the body. The large surface area allows sufficient oxygen intake needed for releasing the large amount of energy required by us. There are two main steps in breathing: Inspiration inhalation is the process of breathing in, by which air is brought into the lungs.
Inspiration involves the following steps: The muscles attached to the ribs on their outer side contract.
This causes the ribs to be pulled out, expanding the chest cavity. The muscle wall between the chest cavity and the abdominal cavity, called diaphragm, contracts and moves downwards to further expand the chest cavity.
The abdominal muscles contract. The expansion of the chest cavity creates a partial vacuum in the chest cavity.
This sucks in air into the lungs, and fills the expanded alveoli. After the exchange of gases in the lungs, the air has to be expelled.
Expulsion of the air from the lungs is called expiration. In this process, muscles attached to the ribs on their inner side contract, and the diaphragm and the abdominal muscles relax. This leads to a decrease in the volume of the chest cavity, which increases the pressure on the lungs.Course Overview.
Lancaster University’s BSc Biomedical Science is accredited by the Institute of Biomedical Science (IBMS). An IBMS-accredited degree, along with a training period in an NHS lab, represents a core route to employment in the NHS as a Biomedical Scientist. The evolution of sexual reproduction describes how sexually reproducing animals, plants, fungi and protists could have evolved from a common ancestor that was a single celled eukaryotic species.
There are a few species which have secondarily lost the ability to reproduce sexually, such as Bdelloidea, and some plants and animals that routinely reproduce asexually (by apomixis and. ADVERTISEMENTS: Human Respiratory System and it’s Mechanism!
The human respiratory system consists of a pair of lungs and a series of air passages leading to the lungs.
The entire respiratory tract (passage) consists of the nose, pharynx, larynx, trachea, bronchi, and bronchioles. Air enters the nose through the nostrils.
When air passes through the nose, [ ]. Quizzes › Science › Cell › Cell Organelle › Cell Organelle Test. Cell Organelle Test. 19 Questions | By Melly | Last updated: Jul 30, Please take the quiz to rate it.
|Course Overview||December 8, NASA: Life with arsenic December 7, Last week, in a much publicized news conference, NASA announced the discovery of a bacterium that can use arsenic instead of phosphorus.|
Cell Organelle Practice Quiz Questions ; Cell Organelle Quiz ; Cell Organelles Quiz ; Organelles And Cell Transport ; What Cell Organelle Are You?
Featured. In this lesson, we'll be explaining the limitations of cell size, specifically the surface area to volume ratio. Then, we'll look at organelles that help cells overcome these limitations.
Play a game of Kahoot!
here. Kahoot! is a free game-based learning platform that makes it fun to learn – any subject, in any language, on any device, for all ages!