Archive for the ‘How does our body function’ Category
January 31st, 2010 | 
Author: Steroids are the hormones, which a human body produces of its own. steroid helps us to overcome stress and to grow bigger during puberty. The amount of steroid secreted within our body must be within the optimal amount. If the secretion goes beyond the normal level, the person may have to face health problems. If you are hale and healthy, it is not necessary for you to take steroids from external sources. But steroids are given along with medicines, for those people who suffer from asthma and body pain. There is another kind of steroid known as anabolic steroid, which is mainly used by athletes, teens and college students, just to build their body. It increases the protein synthesis within our body and hence results in the development of cellular tissues, thus resulting in the buildup of muscles Anabolic steroids are artificially produced hormones and the intake may be in the form of pills, powders and injections. It is illegal to sell, possess or buy these anabolic steroids and no seller can sell these medicines without valid prescriptions. Some steroids have been banned from the market and some remain as legal steroids. Even though legal steroids are available in the market, it is not advisable for the kids and teens to take anabolic steroids. This may create growth related problems in them. Anabolic steroids does not suit everyone, and it causes lots of health problems. Some of them are abnormal growth, mood swings, liver damage, increased chances of getting heart disease and stroke. You might have come across the word doping. Sometimes sportsmen will be banned due to their failure in the doping test. That is due to the intake of steroids just before entering the field. They take it so that they can be lot more energetic inside the field. So take steroids only if you have a genuine reason for using it.
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Imagine you are a caveman out innocently picking berries when suddenly you come nose to nose with a tiger. While you were simply gathering, the tiger was actually hunting, and the sight of you makes his mouth water.
Luckily for you, millions of years of evolution have endowed you with a set of automatic weapons that take over in the event of an emergency. At the sight of the tiger, your hypothalamus sends a message to your adrenal glands and within seconds, you can run faster, hit harder, see better, hear more acutely, think faster, and jump higher than you could, only seconds earlier.
Your heart is pumping at two to three times the normal speed, sending nutrient rich blood to the major muscles in your arms and legs. The tiny blood vessels (called capillaries) under the surface of your skin close down (which consequently sends your blood pressure soaring) so you can sustain a surface wound and not bleed to death. Your eyes dilate so you can see better. Your hairs are erected (to show the hairy prehistoric man bigger).
All functions of your body not needed for the struggle about to commence are shut down. Digestion stops, sexual function stops, even your immune system is temporarily turned off. If necessary, excess waste is eliminated to make you light on your feet.
Your suddenly supercharged body is designed to help level the odds between you and your attacker. Consequently, you narrowly escape death by leaping higher and running faster than you ever could before. With the danger now over, you find a safe place to lie down and rest your exhausted body.
This is called the Fight or Flight response. The hormone responsible for this response is adrenaline. It initiates the sympathetic nerve arousal which causes the change in our body.
Males and females tend to deal with stressful situations differently. Males are more likely to respond to an emergency situation with aggression (fight), while females are more likely to flee (flight), turn to others for help, or attempt to diffuse the situation -’tend and befriend’. During stressful times, a mother is especially likely to show protective responses toward her offspring and affiliate with others for shared social responses to threat.
Fight or Flight response had played a remarkable role in sustaining our species from ancient threats. But in modern era where man does not have much life threatening situations, false alarms are sometimes aroused. Too many false alarms can lead to stress-related disorders like, heart disease, high blood pressure, immune system disorders, migraine headaches, insomnia and sexual dysfunction.
The brain is the center of nervous system and controls the whole functioning of the body. It occupies the cavity of the skull. Its dorsal surface is convex in conformity and its base is more or less flat and uneven. The average mass of the brain of an adult male is 1375 g and that of adult female is 1245 g. The lesser size of female’s brain does not undermine her intelligence.
The brain is basically divided into three parts: Rhombencephalon, Mesencephalon and Prosencephalon which are further divided into different parts.
RHOMBENCEPHALON
Rhombencephalon consists of Myelencephalon(Medulla Oblangatta) and Metencephalon.
Medulla Oblangatta is a direct continuation of the spinal cord into the brain stem. The medulla oblangatta is shaped like a bulb. It originated in association with the development of the organs of statics and acoustics and the branchial apparatus concerned with respiration and circulation. It also contains the nucleus of last four cranial nerves.
The Metencephalon consists of Pons and Cerebellum. Cerebellum is concerned with coordination of movements and balance of the body. It is made of two hemispheres and internally the cerebellum has for nuclei: nucleus fastigi, n.globosus, n.emboliformis and n.dentatus.
Fourth Ventricle is the cavity of Rhombencephalon.
MESENCEPHALON
Mesencephalon is mainly concerned with innervations of eye. Mesencephalon contains subcortical centres of vision, subcortical auditory centres, all ascending and descending pathways and budles of white matter. The dorsal part is tectal lamina and ventral part is cerebral peduncles. The nuclei of third and fourth pair of cranial nerves is present in mesencephalon.
The cavity of mesencephalon is Cerebral Aqueduct.
PROSENCEPHALON
Prosencephalon is the biggest region of the brain. It has two parts.
The Diencephalon
Two main parts are distinguished in it: (a) Thalamencephalon: which consists of Thalamus, Epithalamus and Metathalamus. Thalamus is of great functional significance as it is a relay station for the afferent tracts. (b)Hypothalamus: Its optic part consists of tuber cinerum with the infundibulum and hypophysis cerebri as well as optic chiasma with the optic tract. Its olfactory part consists of mamillary bodies and subthalamic region.
The cavity of the diencephalon is the Third ventricle.
The Telencephalon
The Telencephalon or the endbrain consists of two cerebral hemispheres. Each hemisphere consists of the Pallium, the Rhinencephalon and the Basal ganglion. At the bottom of the fissure which divides the hemispheres is the Corpus Callosum.
The Pallium consists of a large number of sulci and gyri. Based on the deep sulci each hemisphere has five lobes : Frontal, Parietal, Temporal, Occipital and Insula.
Rhinencephalon is the oldest part of forebrain and is concerned with olfactory reception. The three conglomerates of subcortical nuclei distinguished in basal ganglia are corpus striatum, claustrum and amygdaloid nucleus.
The cavity of Telencephalon is lateral ventricles.
The details provided above are just an overview of the anatomy of brain and each part described above further consists of many more minute structures…
The human digestive system comprises of the alimentary canal, associated glands and regions of absorption of food. The digestive system starts from the mouth and ends with the anus.
Oral cavity is the first part of digestive system which comprises of lips, cheeks, tongue, teeth and salivary glands. Lips form the opening of the oral cavity and cheeks forms its lateral walls. Tongue contains the taste buds and is useful in rolling down the bolus. There are 32 permanent teeth in a human adult.
Incisors (8), Canines (4), Premolars (8) and Molars (12). The tooth is made up of a calcified tissue called the dentine. It is covered by the enamel which is the hardest substance in human body. Salivary glands produce the saliva (amylase) which lubricates the food and partially digests the starch in it. The major salivary glands are parotid, sublingual and submandibular gland.
Oesophagus extends from the pharnyx to the stomach (abt 25 cm long). Oesophagus carries bolus from mouth to stomach. The peristaltic movement in oesophagus lets food pass only towards stomach irrespective of the posture of man.
The stomach is an enlarged sac like structure. It is divisible into four regions namely cardia, corpus, fundus and pylorus. The medium in stomach is acidic. The process of digestion practically starts here. The walls of the stomach are made of number of glands which produces gastric juice.
The Small Intestine which in human adult lengths to 7 meters is made of three parts: Duodenum, Ileum and Jejunum. Small Intestine is the part where practically most part of the digestion and absorbtion takes place. The digestion is performed by the digestive enzymes supplied by liver and pancreas. The absorbtion is carried out by finger like projections called Villi presnt in the mucosal wall of the small intestine.
Liver is the largest visceral organ in the human body. It produces bile juice which emulsifies fats and lipids. Bile juice gets stored in gall bladder from where it is supplied into duodenum through common bile duct.
Pancreas consists of two parts: endocrine and exocrine. Endocrine part produces hormones insulin, glucogon and somatostatin. The exocrine part secretes digestive enzymes such as trypsin, chymotrypsin, pancreatic lipase, and pancreatic amylase. These digestive enzymes are poured into duodenum by common bile duct through pancreatic duct.
The large intestine is about 1.5 meters long. The parts of large intestine are Caecum, Ascending colon, Transcerse colon, Descending colon, Sigmoid colon and Rectum. The main function of large intestine is reabsorbtion of nutrients and absorbtion of water.
Anus is the opening at the rectum canal through which the undigested wastes are excreted out of the body.
I hope I would have given you a brief picture of human digestive system.