RESPIRATORY SYSTEM-SECRETS

RESPIRATORY SYSTEM-(SECRETS)

1. Explain the voluntary control of respiration

Voluntary control of respiratory muscles by the motor cortex can override the medullary respiratory centre. This allows us either to speed up ventilation or to hold our breath at will. However, voluntary control is only partial, because if we stop breathing for more than a minute or so, arterial pco2 rises and po2 falls providing a chemoreceptor –driven stimulus to ventilation.

2. What is air hunger?

Increased activity in the vasomotor centre is primarily responsible for cardiovascular adjustments to low blood pressure but also stimulates ventilation. This explains the increased breathing, known as air hunger, which is seen in surgically shocked patients.

3. What is smokers cough?

Individuals who smoke create a constant irritation to the trachea. Overtime, the irritation from smoke can cause the epithelium of trachea to change from a pseudo stratified ciliated columnar to stratified, squamous epithelium. Without cilia, the epithelium cannot clear the mucus and debris. This provides an environment for the growth of microorganism leading to respiratory infections. This trigger the cough reflex commonly called smokers cough.

4. What are the effects of ageing on the respiratory system?

With advancing age, the airways and tissues of the respiratory tract, including the alveoli, become less elastic and more rigid; the chest wall also becomes more rigid. the result is a decrease in lungcapacity.moreover ,a decrease in blood level of o2,decreased activity of alveolar macrophages and diminished ciliary action of the epithelial lining .owing to all these age related factors ,elderly people are more susceptible to pneumonia, bronchitis and other pulmonary disorders.

5. What is the significance of residual volume?

Some amount of air is always present in the lung because of RV or FRC, and therefore continuous exchange of gases is made possible and thereby concentrations of o2 and co2 in blood are maintained constant.

6. Why are venous RBCs more fragile than arterial RBCs?

When blood passes through tissue capillaries, co2 enters into blood and causes chloride shift. (Chloride ions diffuse from plasma into the RBCs).as a result, osmotic pressure inside the RBCs becomes higher than that of plasma. this causes osmotic absorption of fluid into the RBCs.venous RBCs contain therefore the greater quantity of fluid as compared to arterial RBCs .when placed in hypotonic solutions they can take lesser amount of fluid and hence more fragile than arterial RBCs.

PHYSIOLOGY SECRET

PHYSIOLOGY SECRET

Comment on fatigue in diaphragm
Diaphragm is a striated skeletal muscle innervated by phrenic nerve. (C3-C5).Like the heart it must contract in repetitive rhythmical fashion for life. The muscle composition of diaphragm is well suited to the task. Though diaphragm is a skeletal muscle, it is not fatigued.
55% of diaphragm fibers are slow twitch oxidative type: Highly resistant to fatigue.

25% are fasttwitch, oxidative, glycolytic type: Relatively resistant to fatigue.

The remaining 20% are fast twitch glycolytic: susceptible to fatigue.

In general, slow twitch oxidative fibers are arranged with more capillaries, myoglobin, mitochondria and isoenzymes that favors aerobic metabolism. In addition, fast twitch with less capillaries, myoglobin, mitochondria, and isoenzymes that favors anaerobic metabolism.75percentageof muscle fibers have good to excellent endurance characteristics.

PHYSIOLOGY SECRETS

PHYSIOLOGY SECRETS

1. What is amphipathic?
Lipids forms the basic structure of the membrane .the lipid molecules are amphipathic, inotherwords they have a hydrophilic polar region at one end of the molecule and hydrophobic hydrocarbon tail at the other end.
The hydrophilic ends of the lipid molecule line up facing the ICF and ECF.
The hydrophobic tail end faces each other in the interior of the bilayer.

2. What is integral and peripheral membrane protein?
1) Integral or intrinsic proteins bind to the hydrophobic center of the lipid bilayer.
Eg: a).transmembrane protein-span the entire bilayer.
They serve as: channels-through which water-soluble substances can diffuse.
  Carriers-transport materials across the bilayer.
  Pumps-actively transport ions across the bilayer.
  Receptors: initiate intracellular process when activated.
 b) Proteins that is present on only one side of the membrane-
  Eg-enzymes-activate or inactivate various metabolic processes.
2) peripheral-or-Extrinsic-bind to hydrophilic polar heads of lipid or integral protein.
Cytoskeleton-peripheral protein binds to intracellular surface of the membrane.
Glycocalyx-bind to extra cellular surface.

3. What is Michaelis-Menten, kinetics?
Unlike simple diffusion the rate of facilitated diffusion rises as the concentration gradient increases until all the binding sites are filled. At this point the rate of diffusion can no longer rise with increasing point of concentration. This is called saturation or Michaelis –Menten, kinetics.

4. How does the membrane potential affect the rate of diffusion of anions and cations?
Electrical potential produce an electrostatic force. A positive charge inside the membrane will attract anions into the cell and repel cations.net movement of an ion will depend on the balance of the chemical and electrical gradient acting on it that is the electrochemical gradient.

5. Which ions are most important in the osmotic control of cell volume? Why are they important?
Na ions and Cl ions in the ECF and K ions and inorganic anions (po4and sulphates) inside the cell. These ions are important because,
1. They are osmotically active at cell membrane, which have only limited permeability to them
2. They make the largest contributions to the total osmolality of the relevant solutions.
3. There is a concentration gradient across the cell membrane.
This is maintained both by low membrane permeability and by active transport system (for Na and K)
6. What are cell adhesion molecules? CAMs
Cells are attached to each other by cell adhesion molecules. They also transmit signals into and out of cell. These adhesion proteins (viz.laminin, integrin, IgG, Catherin, selectin) play important role in 
1. Embryonic development
2. Formation of N.S
3. Holding tissues together
4. Inflamation and wound healing
5. Metastasis of tumor

7. What is demarcation potential?
If the axon under one of the electrode is damaged, e.g.-by crushing or cutting the nerve (in damaged area, polarity is abolished) then the damaged area becomes negative relative to the healthy portion at rest. Therefore steady potential difference bn: Two electrodes are recorded at rest, called injury (demarcation) potential.

8. What is Retropulsion?
It is the back and forth movement of the chyme caused by forceful propulsion of food against the closed pyloric sphinter.The wave of peristalsis reaches the pyloric sphinter before the chyme,then when the chyme reaches the sphinter ,it is pushed back in to the body of the stomach.

9. What is receptive relaxation?
When the food enters the stomach, the fundus and upper portion of the body relax and accommodate the food. Peristalsis then begins in the lower portion, mixing and grinding permitting small, semi liquid portion to pass through the pylorus and enter the duodenum. Receptive relaxation is vagally mediated and triggered by movement of esophagus and pharynx.

10. What is haustral shuttling?
Bands of muscles divide the large intestine into saclike segments called haustrations.Although haustrations are present when the colon is empty, the entry of food into the colon cause an increase in colonic contractile activity.
The dynamic formation and disappearance of haustral contractions squeeze the chyme, moving back and forth along the colon similar to S.I segmental contractions.

11. What is antral systole?
The contractions of distal stomach caused by peristaltic wave are called antral systole. In addition, can last up to 10sec.waves occur three-4 times/mt

12. What is Ghrelin?
It is a 28a.a polypeptide. It stimulates growth hormone secretion and has pronounced effect on food intake. It is produced in the stomach and arcuate nucleus. The blood levels of it are decreased after food and increased during fasting.

13. What is paralytic secretion?
Claude Bernard observed that cutting the chorda tympani (parasym) in experimental animals produces scanty secretion of thin turbid saliva, which increases to peak on 7th day and decreases in 3rd week. He called it paralytic bcz it was due to cutting the nerve. However, later on it was observed that the secretion is due to increased sensitivity if the gland to adrenaline after cutting the nerve.

14. What is caloric value? State the caloric value of fat, protein and carbohydrate.
The energy liberated from metabolism of 1gm of substance is known as caloric value of that substance.
Fat-9 calories
Protein-4
Carbohydrate-4

15. What is molecular mimicry?
It is a phenomenon that has been discovered as one of the causes for autoimmunity bcz of molecular similarity between foreign and selfpeptides.An example is Rheumatic fever following streptococcal infection. It is due to development of antibodies against streptococcus that cross-react with cardiac myosin and damage the heart. (A portion of cardiac myosin resemble a portion of streptococcal M protein)

POSITIVE THINKING-B+

  POSITIVE THINKING-B+

  Aim high and do your best.
  Think of the cup as half full-not half empty!
  B+
Positive thinking is a mental attitude that admits into the mind thoughts, words and images that are conductive to growth, expansion and success. It is a mental attitude that expects good and favorable results. A positive mind anticipates happiness, joy, health and a successful outcome of every situation and action.

Is your glass half-empty or half-full? How you answer this age-old question about positive thinking may reflect your outlook on life, your attitude toward yourself, and whether you are optimistic or pessimistic.
In fact, some studies show that these personality traits-optimism and pessimism-can affect how well you live and even how long you live.
With this in mind, take a refresher course in positive thinking. Learn how to put positive thinking into action. Positive thinking is a key part of an effective stress management strategy.

SELF-TALK
Self-talk is the endless stream of thoughts that run through your head every day. These automatic thoughts can be positive or negative. Some of your self-talk comes from logic and reason. Other self-talk may arise from misconceptions that you create because of lack of information.

If your thoughts are mostly positive, you are likely an optimistic. If your thoughts are mostly negative, your outlook on life is likely pessimistic.

HEALTH BENEFITS FROM POSITIVE THOUGHTS
*decreases negative stress.
*a sense of well-being and improved health
*increased immunity
*better coping skills during hardships

HOW DO YOU BUILD A POSITIVE ATTITUDE THAT ENSURES YOUR SUCCESS?
You can LEARN to turn negative thinking into positive thinking. The process is simple, but it takes time and practice-you are creating a new habit, after all.

Just follow this “4day attitude diet”
Day1-diet: fill your mind with positives.
Day2-diet: affirm yourself
Day3-diet: think only good things about people
Day4-diet: speak only positive words.

HOW TO ERADICATE AND STOP NEGATIVE THOUGHTS
*be aware of those who do not want to be positive
*avoid negative people
*develop immunity against negative criticism

Here are some examples for negative self-talk and how you might apply a positive thinking twist include:
I have never done it before------It is an opportunity to learn something new.
It is too complicated------------I will tackle it from different angle.
There is no way it will work---I can try to make it work.
No one bothers to communicate with me----I will see if I can open the channels of communication.

THE INTRINSIC SYSTEM OF THE BRAIN-the secret to a positive attitude and success

Your brain is an amazing organ. It contains about a hundred thousand miles of blood vessels (160,000 kilometers) and about 100 billion neurons. These neurons are able to perform about 10 quadrillion operations per second. The capacity of your brain is virtually unlimited.
The brain controls every aspects of your life. You make decisions, take actions, hold onto beliefs and habits, and maintain your body functions all in your brain. This is why it is important that you learn to harness the power of your mind and develop a positive attitude and positive habits and beliefs.
In order to harness the power of your brain, you need to understand the basics of how it works. It can be divided into two areas, the conscious and the unconscious brain.

If you think of your brain as a car and driver, your conscious brain is the driver and the subconscious brain is the car itself. The conscious brain-the driver, decides where to take the car. Ultimately the car itself, the subconscious mind that will get you where you want to go.
REPROGRAMMING
Most decisions do not lead to success because a decision is made with the conscious brain. Over 90% of time, your old habits and beliefs will overpower your will in a short period. Your conscious will power does not have the strength to overcome your old habits and beliefs, which are held in your subconscious brain.
If you understand how the subconscious brain, how to start a subconscious mind reprogramming, you can overcome the subconscious mind, and develop a positive attitude.
HIGHER BRAIN FUNCTIONS
What are the brain structures involved during higher cortical functions, such as cognition, and how do they interact with structures involved in guiding our behaviour?scientists suggest that posterior medial frontal cortex is involved in functions of cognitive control, such as monitoring of unfavorable outcomes ,response errors, response conflict. Activity in the left side of the prefrontal cortex is associated with positive emotional responses and has a stronger immune response against disease.
Numerous scientific studies show that keeping a positive attitude can keep a person healthy.
Aim high and do your best.
Think of the cup as half full –not half-empty!
B+



   

HAPPY NEW YEAR 2009

Best Wishes For a Happy and Prosperous New Year2009

POSITIVE STEPS TO REDUCE ANIMAL TESTING

  POSITIVE STEPS TO REDUCE ANIMAL TESTING
   

Animal testing has long been considered the gold standard for environmental toxicology, but animal testing takes a long time and entails the death of animals to acquire data. Even more, the results cannot always extrapolate to humans.
In order to reduce the number of animals used in experiments without jeopardizing medical research the FRAME-(Fund for the Replacement of Animals in Medical Experiments) laboratory will try to grow human tissue cultures in which drugs can be tested.

Using Biochips instead of Animals for Testing-
A new biochip technology could vastly reduce animal testing in the cosmetics and other chemical industries ,as well as reduce its use in the development of new pharmaceuticals.when biochips are used together the result is promising and affordable alternative to animal based toxicology screening and a direct route to developing safe, effective drugs.  
Thus, the research team views the combined chips as an efficient, more accurate way to test drug compounds for human toxicity earlier in the discovery process.
Biochip-
A biochip is a collection of miniaturized test sites (micro arrays) arranged on a solid substrate that permits many tests to be performed at the same time in order to achieve higher out put and speed.
(Micro array-the dense 2 dimensional grid of biosensors is the critical component of a biochip platform.)
A biochip is made up of more than 1000 human cell cultures suspended in a special 3-dimensional gel and utilized on a slide to be viewed under the microscope; an individual cell culture can investigate if a special chemical is toxic to humans.
Typically, a biochip surface area is no larger than a fingernail. Like a computer chip that can perform millions of mathematical operation in one second, a biochip can perform thousands of biological reaction. Such as decoding genes, in a few seconds.
Extending the use of a biochip-
Even more exciting news about the biochip is that scientists can add in other kinds of cells. In this way, a researcher could add in a lung cell for instance, which would thus check if the chemical is toxic to lungs. This new technology now allows for scientist to asses the toxicity of a chemical on multiple organs, rather than just skin alone.  
Positive steps to reduce animal testing-
While this new biochips is not yet a complete replacement for animal testing. It is an exciting and positive step in the right direction for the chemical industry and pharmaceutical .ultimately; it pulls us a bit closer to finding a way to replace animals in laboratory testing. Biochips also carry other benefits such as reasonable cost rapid output and of course, it does not require the use of animals for testing.

SMOKING-a heart-breaking habit

SMOKING-a heart- breaking habit

IF YOU SMOKE, QUIT AND IF YOU DON’T SMOKE, DON’T START

Smokers put themselves at higher risk for everything from asthma to cancer to heartdisease.Far more serious is the fact that when tobacco is burned (it reaches 925 c at the glowing tip of a lit cigarette),it is broken down into its chemical elements from which lethal chemical compounds are created. The period between puffs allows time for ammonia,acetone,formaldehyde,hydrogen cyanide, and some 4000 other chemicals to become irritants,poisons,mutagens,nerve gases and more than 40 types of carcinogens. In addition, since these chemicals are released into the air, they affect other people present as well.

Among the most devastating effects are those to the heart. In addition to increasing blood pressure and heart rate, many of the chemicals in tobacco also raise ‘bad’-LDL cholesterol while decreasing ‘good’-HDL cholesterol. At the same time, they constrict the blood vessels, decreasing blood flow and oxygen to all of the organs, particularly the heart. Chemical residue damages the arteries, making the blood stickier. This increases the risk of blood clots and dramatically raises the risk of a heart attack or stroke. Increases the risk of infertility in both men and women. If you have high blood pressure or high cholesterol and you smoke, you are putting yourself at very high risk of a heart attack.

The hazards do not end with heart disease and cancer .Because smoking impairs the body’s ability to keep the lungs clear, it contributes to such respiratory illness as asthma, bronchitis, pneumonia and emphysema. It also increases the risk of hipfracture, peptic ulcers, cataracts, and premature mental decline.

DID YOU KNOW-
*Each year 390,000 Americans die from the effects of smoking.
*cigarette smokers have more than twice the risk of heart attack.
*cigarette smokers have 2 to 4 times the chance of cardiac arrest.
*giving up smoking rapidly reduces the risk of heart disease.
If you smoke, quit .if you do not smoke, do not start.
Avoid long-term exposure to smoke and protect children from it.

There are approximately 4000 chemicals in cigarette smoke. Many of them are toxic and affects from the functioning of organs to efficiency of body’s immune system.
The three main ingredients of cigarette smoke are,
Nicotine, carbonmonoxide, tar.
Nicotine: highly addictive, reaches the brain in less than 10 seconds it has been found in every part of the body and in breast milk.
Corbonmonoxide: Tasteless, odorless and poisonous gas taken up quickly by the blood stream &impairs breathing. It binds to Hb in RBC preventing affected cells from carrying a full load of o2.
Tar: carcinogenic, around 70% of tar is deposited in the smoker’s lung. It is also responsible for the yellow-brown staining of smoker’s fingers and teeth.
Other harmful chemicals-
Acetone, ammonia, arsenic, benzene, cadmium, and formaldehyde.

Immediate effects:
*initial stimulation then reduction in brain and nervous system activity.
*mild euphoria.
*Enhanced alertness and concentration
*Feeling of relaxation
*Decreased blood flow to fingers and toes
*dizziness, nausea, acid in the stomach
*decrease appetide, taste and smell
Longtermeffects:
Death due to cancer, heart diseases and chronic obstructive pulmonary disease.
Passive-second hand smoke-environmental tobacco smoke
-can cause a number of health problems including heart diseases, lung cancer and irritation of eyes and nose.

Tolerance and dependence-
People who use tobacco tend to develop a tolerance to the effect of nicotine very quickly. This means they need to smoke more and more in order to get the same effect. Dependence on nicotine can be physiological, psychological or both.

Withdrawal-
If a person suddenly stops smoking or reduce the amount they use, they will experience withdrawal because their body has to readjust to functioning without the drug. Most of the symptoms will disappear within days or weeks of quitting smoking, but craving may persist for years after stopping using tobacco.
Symptoms include craving, irritability, agitation, depression and anxiety,
Insomnia and disturbed sleep pattern, increased appetite and weight gain, restlessness, loss of concentration, headache, sorethroat body ache and stomach upset.

Effect of smoking on serum lipid and lipoprotein:
Smoking is accepted as a major risk factor for ischemic heart disease (IHD), hypertension, and hyperlipidemia.certain components (nicotine and co)have been reported to be responsible for the development of ischemic heart disease by increasing the plasma catecholamine and producing hypoxia. On the other hand smoking alter plasma lipoprotein levels increases the susceptibility of LDL to oxidation. Smoking stimulates the oxidation of LDL particles producing significant increase of triglycerides-TG and decrease of HDL cholesterol. (HDL is known to be an important protective factor for ischemic heart disease.

Smoking produces adverse effects on lipid profile and increases the risk of cardiovascular diseases.
Reverse cholesterol transport-is an antiatherogenic process. (Excess cholesterol is transported from peripheral tissue back to liver or to other peripheral tissue that in need cholesterol.)
LCAT-Lecithin cholesterol acetyl transferase a key factor in esterification of plasma cholesterol and reverse cholesterol transport.
Smoking-*increases serum levels of TG, LDL.
*decreases serum HDL
*decreases LCAT activity.
Chronic smoking results in systemic oxidants-antioxidants imbalance as reflected by increased products of lipid peroxidation and decreased levels of antioxidants like vit-a&c.inflamatory response as confirmed by increased c-reactive protein,(CRP), fibrinogen,interleukin,increased WBC count have been reported.
TIPS TO KICK THE HABIT:
*First 3 or 4 days of being smoke –free are the toughest. If you can get through the 1st week without cigarette, your chances of quitting forever are good.
*to distract ,choose a substitute, such as sugar free chewing gum or candy,whistling,singing,chewing on carrot-sticks or sucking a lollipop.
*the first blast of nicotine in the morning increases energy and alertness. To achieve this state, try a round of morning exercises. Then concentrate on music, meditation or yoga.
THE MYTH OF ‘safer’ CIGARETTES-
Many cigarette manufacturers have introduced ‘low tar’, and ‘low nicotine’ version. HOWEVER, ARE THEY REALLY SAFER?-NO. In addition, do not forget that ‘additive free’ cigarette still have addictive nicotine and cancer causing tar.
Ironically, cigarettes made prior to 1950nwere so harsh tasting that smokers inhaled less, which actually reduced their risk.

IF YOU SMOKE, QUIT AND IF YOU DO NOT SMOKE DO NOT START.