Thursday, February 26, 2009

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)

Wednesday, February 11, 2009

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+