RELAXATION SCIENCE

  😎 HUMAN EXCRETORY SYSTEM  😎  In humans, the excretory system consists of a pair of kidneys, one pair of ureters, a urinary bladder and a urethra.  Kidneys are reddish brown, bean shaped structures situated between the levels of last thoracic and third lumbar vertebra close to the dorsal inner wall of the abdominal cavity.  Each kidney of an adult human measures 10-12 cm in length, 5-7 cm in width, 2-3 cm in thickness with an average weight of 120- 170 g. Towards the centre of the inner concave surface of the kidney is a notch called hilum through which ureter, blood vessels and nerves enter.  Inner to the hilum is a broad funnel shaped space called the renal pelvis with projections called calyces.  The outer layer of kidney is a tough capsule.  Inside the kidney, there are two zones, an outer cortex and an inner medulla.  The medulla is divided into a few conical masses (medullary pyramids) projecting into the calyces (sing.: calyx)....

 SOLID WASTES  Solid wastes refer to everything that goes out in trash.  Municipal solid wastes are wastes from homes, offices, stores, schools, hospitals, etc., that are collected and disposed by the municipality.  The municipal solid wastes generally comprise paper, food wastes, plastics, glass, metals, rubber, leather, textile, etc.  Burning reduces the volume of the wastes, although it is generally not burnt to completion and open dumps often serve as the breeding ground for rats and flies.  Sanitary landfills were adopted as the substitute for open-burning dumps.  In a sanitary landfill, wastes are dumped in a depression or trench after compaction, and covered with dirt everyday.  Landfills are also not really much of a solution since the amount of garbage generation specially in the metros has increased so much that these sites are getting filled too.  Also there is danger of seepage of chemicals, etc., from these landfills polluting th...

AIR POLLUTION   We are dependent on air for our respiratory needs.  Air pollutants cause injury to all living organisms.  They reduce growth and yield of crops and cause premature death of plants.  Air pollutants also deleteriously affect the respiratory system of humans and of animals.  Harmful effects depend on the concentration of pollutants, duration of exposure and the organism.  Smokestacks of thermal power plants, smelters and other industries release particulate and gaseous air pollutants together with harmless gases, such as nitrogen, oxygen, etc.  These pollutants must be separated/ filtered out before releasing the harmless gases into the atmosphere.  Electrostatic precipitator There are several ways of removing particulate matter; the most widely used of which is the electrostatic precipitator, which can remove over 99 per cent particulate matter present in the exhaust from a thermal power plant.  It has electrode wires that are m...

 DOUBLE CIRCULATION   The blood flows strictly by a fixed route through Blood Vessels—the arteries and veins.  Basically, each artery and vein consists of three layers: an inner lining of squamous endothelium, the tunica intima, a middle layer of smooth muscle and elastic fibres, the tunica media, and an external layer of fibrous connective tissue with collagen fibres, the tunica externa.  The tunica media is comparatively thin in the veins.  As mentioned earlier, the blood pumped by the right ventricle enters the pulmonary artery, whereas the left ventricle pumps blood into the aorta.  The deoxygenated blood pumped into the pulmonary artery is passed on to the lungs from where the oxygenated blood is carried by the pulmonary veins into the left atrium.  This pathway constitutes the pulmonary circulation. The oxygenated blood entering the aorta is carried by a network of arteries, arterioles and capillaries to the tissues from where the deoxygenated bl...

  RADIOACTIVE WASTES  Initially, nuclear energy was hailed as a non-polluting way for generating electricity.  Later on, it was realised that the use of nuclear energy has two very serious inherent problems.  The first is accidental leakage, as occurred in the Three Mile Island and Chernobyl incidents and the second is safe disposal of radioactive wastes.  Radiation, that is given off by nuclear waste is extremely damaging to biological organisms, because it causes mutations to occur at a very high rate.  At high doses, nuclear radiation is lethal but at lower doses, it creates various disorders, the most frequent of all being cancer.  Therefore, nuclear waste is an extremely potent pollutant and has to be dealt with utmost caution.  It has been recommended that storage of nuclear waste, after sufficient pre-treatment, should be done in suitably shielded containers buried within the rocks, about 500 m deep below the earth’s surface.  However,...

😀RESPIRATORY ORGANS 😀 👉This cycle of change of O2 from the weather with CO2 introduced via way of means of the telephones is referred to as breathing, commonly referred to as breath .   👉 Uncommon vascularised systems referred to as gills ( branchial breath ) are used by the bulk of the amphibian arthropods and molluscs though vascularised sacks referred to as lungs (aspiratory breath) are used by the earthly systems for the buying and selling of gases. 👉 Among vertebrates, fishes use gills whilst creatures of land and water, reptiles, winged animals and heat blooded creatures breathe thru lungs. 👉 Creatures of land and water like frogs can breathe thru their soggy skin ( cutaneous breath ) moreover.  Human Respiratory System   We have more than one outer nostrils establishing out over the higher lips.  It activates a nasal chamber thru the nasal phase.  The nasal chamber opens into the pharynx , a section of that is the primary access for meals and air....

😎 Human Circulatory System 😎 Human circulatory framework, additionally called the blood vascular framework comprises of a strong chambered heart, an organization of shut fanning veins and blood, the liquid which is circled.  Heart, the mesodermal determined organ, is arranged in the thoracic hole, in the middle of the two lungs, marginally inclined to one side. It has the size of a held clench hand. It is ensured by a twofold walled membranous sack, pericardium, encasing the pericardial liquid.  Our heart has four chambers, two moderately little upper chambers called atria and two bigger lower chambers called ventricles.  A slight, solid divider called the interatrial septum isolates the privilege and the left atria, while a thick-walled, the between ventricular septum, isolates the left and the correct ventricles.  The chamber and the ventricle of a similar side are likewise isolated by a thick stringy tissue called the atrio-ventricular septum.  Notwithstand...

DISORDERS OF DIGESTIVE SYSTEM

  DIGESTIVE GLANDS Salivary gland   Saliva is mainly produced by three pairs of salivary glands, the parotids (cheek), the sub-maxillary/submandibular (lower jaw) and the sub-linguals (below the tongue).  These glands situated just outside the buccal cavity secrete salivary juice into the buccal cavity. liver  Liver is the largest gland of the body weighing about 1.2 to 1.5 kg in an adult human.  It is situated in the abdominal cavity , just below the diaphragm and has two lobes. The hepatic lobules are the structural and functional units of liver containing hepatic cells arranged in the form of cords.  Each lobule is covered by a thin connective tissue sheath known the Glisson's. The bile secreted by the hepatic cells passes through the hepatic ducts and is stored and concentrated in a thin muscular sac known the gall bladder.  The duct of Gall bladder (cystic duct) along with the hepatic duct from the liver forms the common bile duct The bile...

  DIGESTIVE SYSTEM 👉 This process of conversion of complex food substance to simple absorbable forms is known as DIGESTION.   👉 The alimentary canal opening the mouth and posterior/ending through the anus . MOUTH 👉 The mouth area is known as buccal cavity / oral cavity. 👉 The oral cavity has number of teeth and muscular tongue. 👉 Each tooth is embedded is a socket of jaw bone. This type of attachment is known as THECODONT. 👉 Majority mammals two set of teeth, set of milk/deciduous teeth replaced by a set of permanent/adult teeth . This is known as Diphyodont 👉 Adult human has 32 permanent teeth  which are 4 types Incisors (I), Canine (C), premolars (PM) and Molars (M). 👉 Dental formula 2123/2123 👉 The hard chewing surface of the teeth , made up enamel , helps in the mastication of food.  👉 The tongue is a freely movable muscular organ attached to the floor of the oral cavity by the frenulum .  👉 The upper surface of the tongue has small projec...