Respiration
The air we breathe in goes through the nose, or sometimes through the mouth, via the throat (pharynx) and the larynx (voice box) into the wind-pipe (trachea), and thence into the lungs. The trachea divides into two branches, called bronchi, which lead to the left and right lungs. These bronchi keep on dividing into smaller bronchi, like the branches of a tree. The terminal ends of these bronchi are called bronchioli. The brochioli end up in tiny cavities called alveoli (like the twigs of a tree, which end up in the leaves). The air is drawn into each alveolus during inspiration (breathing in). The oxygen in the air enters the capillaries (the smallest blood vessels) in the alveoli, and the excess of carbon dioxide is. discharged into the alveoli from the same capillaries. During expiration (breathing out) the carbon dioxide is expelled into the air.The chest cavity expands during inspiration by the outdrawing of the muscles of the chest and the downward movement of the diaphragm, which is the thick muscular wall that separates the chest cavity from the abdominal cavity.
Blood, heart, and circulation
Blood is essential for life. Blood is circulated to all parts of the body, by the action of the heart, through a network of blood vessels, which are referred to as arteries and veins. The heart is about the size of the fist (closed hand). It is enclosed within a sac called the pericardium, and is situated inside the chest on the left side. It pumps the blood to the periphery through the arteries, and the veins bring back the blood from the periphery to the heart. The terminal ends of arteries which are microscopic in size are referred to as capillaries. At this point the capillaries are referred to as the arterial capillaries.The arterial capillaries gradually become venous capillaries, which ends up as veins. At the arterial end of the capillary, Oxygen as well as the fluid comes out of the blood and bathes the cells, thus supplying them with Oxygen and nutrients. At the venous end of the capillary, fluid and carbon dioxide (which the body needs to get rid of) flow back into the capillary, and thence into veins. The veins take back this blood to the heart, which pumps the blood into the lungs. If we cut a finger. It would cut through some of the small blood vessels (capillaries) which cannot seen by the naked eye. That is why blood comes out through a wound.
The heart can be best described as an organ consisting of two pumps, which are joined together and exist side by side. The left side of the heart (left pump) consists of two chambers. The upper and smaller chamber, the left atrium – receives oxygenated blood from the lungs. This oxygenated blood flows (from the left atrium) through a valvular opening called the mitral valve, to a bigger and stronger chamber called the left ventricle. The left ventricle pumps this blood into a large artery called the aorta through a valve called the aortic valve. From the aorta the blood is transported through its many arterial branches which ends up in tiny vessels called capillaries, into all parts of the body into the space between cells. After delivering Oxygen and other substances the blood is brought back to the right side of the heart through a network of veins. The blood in the veins contain less oxygenated blood but large amount of Carbon dioxide when compared to the blood in the arteries. The right side of the heart also consist of two chambers. The smaller chamber, the right atrium which is situated above, receives the venous blood from all parts of the body. This venous blood flows from the right atrium through a valve called the tricuspid valve to the right ventricle. The right ventricle pumps the venous blood through a valve called the pulmonary valve into the lungs. In the lungs the blood gives up a large amount of carbon dioxide, and takes in oxygen. It is then returned to the left atrium.
Monday, August 5, 2013
The mind as a controlling agent
Most people think that their behavior is controlled by a rational mind, and that therefore behavior is within voluntary control through will power. This view promoted by religions and philosophers until the 19th century, received a setback in the 20th century. That was when Sigmund Freud pointed out that there are many activities of our minds that are not within our control and which influence our behavior a great deal. Just imagine the last time you took a bath. How many acts in that procedure did you perform with full consciousness? Usually not many. The example of the iceberg is a good one for the mind; a large part of our minds remains submerged and beyond consciousness - what Freud called the subconscious mind. Its influence on our behavior is great, as the unconscious part of the mind is large. Take the example of a parent who meets out harsh punishment to a child for a minor misdemeanor. The parent may be having an unconscious fear of loss of control of the child. This fear may be either due to his childhood experience or due to the experience of a brother who went out of control and ruined his life. We often notice that mothers overprotect their beautiful daughters. The mothers are guided either by their childhood experience when they received undue attention from males or even had a traumatic (painful) sexual experience. If they are asked why they are harsh to a child or why they are overprotecting a child, they cannot explain these unconscious fears. All you hear would be some common excuse usually a rational one.
Have you heard of the famous Freudian slip? We say something by mistake when we want to say something else. The thing said in mistake may well be true or expose something about you. Next time you catch yourself with a slip of the tongue, think about it. So most of our actions are not all that rational. There are many unconscious motives to our behavior. One such unconscious motive is to defend against injury to our self-esteem. We defend our self-esteem in many ways. These are called defense mechanisms. Take the example of an office worker who is taken to task for poor work by his boss in the office. He feels bad but does not say anything to his boss. That evening he beats up his wife over a minor conflict. He has transferred his aggression from boss to wife. Has somebody who accused you of harboring ill feelings towards him surprised you? You never felt that way towards him, but it was probably he who had ill feelings towards you. But since he cannot accept that fact, he unconsciously projects it onto you. People often project their own hostility towards rulers and accuse them of planning to cause harm to people. People project their own hostility towards neighbors, and claim the neighbors are indulging in “charms” against them. There are many such mechanisms of defense against injury to self-esteem. Some are harmless but in some cases we begin to believe ourselves.
Mood and behavior
Our moods refer to the state of our emotions. When we are depressed, our actions are guided by depression. We may lose confidence in our ability to work, have fears of making mistakes, and keep away from the company of friends, but perceive them as rejecting us. In the same way, when anxious, it shows in our behavior as in the stuttering and sweating public speaker who is a first timer. We often learn to avoid people who, and situations that, make us anxious. This in tum increases the problem of anxiety. Another state of mind recognized by psychologists is "learned helplessness". Those who fail repeatedly in life learn and adopt failure as a way of life. They soon give up trying. This is seen at a society level in many third world countries. The poor adopt fatalism as a determinant of their lives. This creates major obstacles to progress in their lives and in society, as a large segment of the population remains socially and economically crippled and resigned to their fate. At an individual level, it has been demonstrated that those patients who give up fighting against an illness, such as cancer, tend to die earlier than those who fight the illness do. Tied up with “learned helplessness“ is the influence of belief. We know now, that merely the belief that one can do well helps a person perform better and achieve. It can be said that believing in one's self is the first and essential step towards success.
Have you heard of the famous Freudian slip? We say something by mistake when we want to say something else. The thing said in mistake may well be true or expose something about you. Next time you catch yourself with a slip of the tongue, think about it. So most of our actions are not all that rational. There are many unconscious motives to our behavior. One such unconscious motive is to defend against injury to our self-esteem. We defend our self-esteem in many ways. These are called defense mechanisms. Take the example of an office worker who is taken to task for poor work by his boss in the office. He feels bad but does not say anything to his boss. That evening he beats up his wife over a minor conflict. He has transferred his aggression from boss to wife. Has somebody who accused you of harboring ill feelings towards him surprised you? You never felt that way towards him, but it was probably he who had ill feelings towards you. But since he cannot accept that fact, he unconsciously projects it onto you. People often project their own hostility towards rulers and accuse them of planning to cause harm to people. People project their own hostility towards neighbors, and claim the neighbors are indulging in “charms” against them. There are many such mechanisms of defense against injury to self-esteem. Some are harmless but in some cases we begin to believe ourselves.
Mood and behavior
Our moods refer to the state of our emotions. When we are depressed, our actions are guided by depression. We may lose confidence in our ability to work, have fears of making mistakes, and keep away from the company of friends, but perceive them as rejecting us. In the same way, when anxious, it shows in our behavior as in the stuttering and sweating public speaker who is a first timer. We often learn to avoid people who, and situations that, make us anxious. This in tum increases the problem of anxiety. Another state of mind recognized by psychologists is "learned helplessness". Those who fail repeatedly in life learn and adopt failure as a way of life. They soon give up trying. This is seen at a society level in many third world countries. The poor adopt fatalism as a determinant of their lives. This creates major obstacles to progress in their lives and in society, as a large segment of the population remains socially and economically crippled and resigned to their fate. At an individual level, it has been demonstrated that those patients who give up fighting against an illness, such as cancer, tend to die earlier than those who fight the illness do. Tied up with “learned helplessness“ is the influence of belief. We know now, that merely the belief that one can do well helps a person perform better and achieve. It can be said that believing in one's self is the first and essential step towards success.
The brain and nervous system
All our thinking processes physical activities and sensations, are initiated, controlled, and co-ordinated by the brain and nervous system. If you accidentally put your hand into some hot water, you will pull it away immediately. This response (called a reflex) is brought about by messages that are sent at high speed through the nervous system. The brain is like an extremely complicated computer, with thousands of electrical messages traveling from place to place. But it is much more than a computer because it makes us conscious persons with feelings and emotions.
The skull encloses the brain. The spinal cord comes down from it and goes down the spine (vertebral column). The human brain is of a soft consistency. It has a soft material on the outside called the grey matter which contains the basic cell units of the brain. These cells are called neurons; there are about 100 billion neurons in the brain. In the deeper parts of the brain there is a whitish firm material, called the while matter, which contains the connecting tracts, which carry the messages from the neurons. The brain is divided into the - cerebrum, cerebellum, and brain stem. Surrounding the soft brain tissue on the outside are two membranes (the meninges) with a thin layer of fluid (cerebro-spinal fluid, CSF) between them. The CSF nourishes the brain and also serves as a shock absorber, so that the brain is cushioned from damage when a person jumps around or bangs the head. There is a cavity in the inside of the brain, which is filled with CSF. This cavity continues as a canal inside me spinal cord. Doctors put in a needle at the back of the spine and get a small amount of CSF (Present between the two coverings of the meninges) for examination, to diagnose diseases such as meningitis and encephalitis.
The functions of the brain and nervous system may be broadly divided into; Higher functions such as thinking, speaking; remembering things (memory), emotions, appreciation of music; motor functions such as movements of the different parts of the body, sensory functions like appreciation of sensations such as pain, touch, seeing, hearing, taste, and smell, balance and coordination of movement in the different parts of the body and involuntary (unintentional) functions. Involuntary functions are two types, regular functions such as breathing and the beating of the heart and certain involuntary reactions with are referred to as reflexes which are usually take place at the level of the spinal cord.
The cerebrum controls the higher functions as well as motor and sensory functions. It is divided into 2 halves (left and right) which are called cerebral hemispheres. The left hemisphere controls the right side of the body, and the right hemisphere the left side of the body. The left hemisphere is said to be dominant in right handed people, and the right hemisphere in left handed people. The cerebellum is situated at the back of the brain. Its main function is to co-ordinate movements of the skeletal muscles and help maintain balance, a function which it shares with the inner ear. The cerebrum and cerebellum lead to the brain stem, which continues downwards as the spinal cord. The Spinal cord is a cylindrical structure that comes down through the vertebral column (spine) to the lower part of the back of the body. Nerves proceed from the brain stem and spinal cord to all parts of the body. In this way every part of the body is connected to the brain which ultimately controls all its activities.
The skull encloses the brain. The spinal cord comes down from it and goes down the spine (vertebral column). The human brain is of a soft consistency. It has a soft material on the outside called the grey matter which contains the basic cell units of the brain. These cells are called neurons; there are about 100 billion neurons in the brain. In the deeper parts of the brain there is a whitish firm material, called the while matter, which contains the connecting tracts, which carry the messages from the neurons. The brain is divided into the - cerebrum, cerebellum, and brain stem. Surrounding the soft brain tissue on the outside are two membranes (the meninges) with a thin layer of fluid (cerebro-spinal fluid, CSF) between them. The CSF nourishes the brain and also serves as a shock absorber, so that the brain is cushioned from damage when a person jumps around or bangs the head. There is a cavity in the inside of the brain, which is filled with CSF. This cavity continues as a canal inside me spinal cord. Doctors put in a needle at the back of the spine and get a small amount of CSF (Present between the two coverings of the meninges) for examination, to diagnose diseases such as meningitis and encephalitis.
The functions of the brain and nervous system may be broadly divided into; Higher functions such as thinking, speaking; remembering things (memory), emotions, appreciation of music; motor functions such as movements of the different parts of the body, sensory functions like appreciation of sensations such as pain, touch, seeing, hearing, taste, and smell, balance and coordination of movement in the different parts of the body and involuntary (unintentional) functions. Involuntary functions are two types, regular functions such as breathing and the beating of the heart and certain involuntary reactions with are referred to as reflexes which are usually take place at the level of the spinal cord.
The cerebrum controls the higher functions as well as motor and sensory functions. It is divided into 2 halves (left and right) which are called cerebral hemispheres. The left hemisphere controls the right side of the body, and the right hemisphere the left side of the body. The left hemisphere is said to be dominant in right handed people, and the right hemisphere in left handed people. The cerebellum is situated at the back of the brain. Its main function is to co-ordinate movements of the skeletal muscles and help maintain balance, a function which it shares with the inner ear. The cerebrum and cerebellum lead to the brain stem, which continues downwards as the spinal cord. The Spinal cord is a cylindrical structure that comes down through the vertebral column (spine) to the lower part of the back of the body. Nerves proceed from the brain stem and spinal cord to all parts of the body. In this way every part of the body is connected to the brain which ultimately controls all its activities.
Alimentary tract, food digestion
The food that we eat (or drink) enters the alimentary tract, which is the passage that starts at the mouth, passes through the food-pipe (esophagus), stomach, small and large intestine, rectum (lower end of bowel) and ends at the anus. The part of this passage from the stomach downward is also referred to as the gastrointestinal tract. Digestion of food starts in the mouth, firstly by the act of biting and chewing, and secondly through the action of the saliva. Saliva, which comes from small glands (salivary glands) situated below and on the side of the jaws, contains biochemical substances called enzymes. Enzymes that play a part in the digestion of food are referred to as digestive juices. These salivary enzymes start the presses of digestion. Further digestion takes place in the stomach (with the help of other enzymes and hydrochloric acid). Partially digested food passes from the stomach into the duodenum (the part of the tract immediately below the stomach). Pancreatic enzymes-enzymes produced in the pancreas, which is a small organ situated behind and below the stomach – are transported to the duodenum through a small tube (the pancreatic duct). These pancreatic enzymes, trypsin being one of the most important for digestion of proteins, play a most effective role in the main process of digestion of the fats, proteins and carbohydrates. From the duodenum the digested food passes to the small intestine, where intestinal juices (from the cells of the lining of the intestine) further help to complete the process of digestion.
In the small intestine, the digested foods are absorbed into the blood stream, which carries them into the liver. The undigested and unabsorbed food, along with most of the water and the intestinal juices, now passes on to the large intestine (colon). At the junction of the small and large intestine is a small outgrowth of the intestine, called the appendix. The terminal part of the large intestine is called the rectum. The opening of the rectum to the outside is called the anus. In the colon most of the water and minerals are absorbed. What is left behind is excreted as stools (feces).
The liver is situated in the upper part of the abdomen to the right of the stomach. In the liver, the nutrients are reassembled to suit the needs of the body, and distributed to the various parts of the body. Some nutrients, (e.g. vitamins A and D, folic acid, vitamin B 12, iron, etc.) are stored in the liver. In addition to nutrients, other substances are absorbed and transported to the liver. These may be drugs, alcohol, poisons etc. The liver has a limited capacity to safeguard the body against harmful substances, by neutralizing the harmful effects. For example alcohol is utilized to provide energy (calories) with the aid of Vitamin B 1. As a result of the various activities that go on in the liver; some waste products are formed within it. Most of these are expelled into the duodenum as a thick greenish-black liquid called bile. Bile contains substances such as bile pigments (resulting from the breakdown of red blood cells), bile salts, cholesterol, and some enzymes; Bile drains out of the liver through a small tube (bile duct) into the gall bladder, and from there into the duodenum.
In the small intestine, the digested foods are absorbed into the blood stream, which carries them into the liver. The undigested and unabsorbed food, along with most of the water and the intestinal juices, now passes on to the large intestine (colon). At the junction of the small and large intestine is a small outgrowth of the intestine, called the appendix. The terminal part of the large intestine is called the rectum. The opening of the rectum to the outside is called the anus. In the colon most of the water and minerals are absorbed. What is left behind is excreted as stools (feces).
The liver is situated in the upper part of the abdomen to the right of the stomach. In the liver, the nutrients are reassembled to suit the needs of the body, and distributed to the various parts of the body. Some nutrients, (e.g. vitamins A and D, folic acid, vitamin B 12, iron, etc.) are stored in the liver. In addition to nutrients, other substances are absorbed and transported to the liver. These may be drugs, alcohol, poisons etc. The liver has a limited capacity to safeguard the body against harmful substances, by neutralizing the harmful effects. For example alcohol is utilized to provide energy (calories) with the aid of Vitamin B 1. As a result of the various activities that go on in the liver; some waste products are formed within it. Most of these are expelled into the duodenum as a thick greenish-black liquid called bile. Bile contains substances such as bile pigments (resulting from the breakdown of red blood cells), bile salts, cholesterol, and some enzymes; Bile drains out of the liver through a small tube (bile duct) into the gall bladder, and from there into the duodenum.
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