PHYSIOLOGY TUTORIAL

PHYSIOLOGY TUTORIAL

What are the angles formed by extra ocular muscles with the visual axis in primary position? Explain the movements on the different direction of visual axis.

The relative importance of primary and secondary actions of extra ocular muscles depends on the direction of visual axis.

Medial and lateral recti lie on the horizontal meridian of the globe. Their functions are relatively simple and antagonistic. Contraction of medial rectus adducts and lateral rectus abducts the globe.

Superior and inferior recti subtend a 23° angle with the visual axis when the eye is in primary position.

When the eye is abducted 23°

The superior rectus acts solely as an elevator,

The inferior rectus acts solely as depressor.

When the eye is adducted 67°

The superior rectus acts solely to incyclotort the globe

The inferior rectus acts solely to excyclotort the globe.

Superior oblique –this vector plane subtends a 54° angle with the visual axis when the eye is in primary position.

When the eye is adducted 54°

Superior oblique acts solely to depress the globe

When the eye is abducted 36°

Superior oblique acts to incyclotort the globe.

Inferior oblique-subtends a 51° angle with visual axis when the eye is in primary position.

When the eye is adducted 51°

Inferior oblique solely elevates the globe.

When the eye is abducted 39°

Inferior oblique solely excyclotort the globe.

A THOUGHT FOR TODAY

Never leave till tomorrow, which you can do today.
Benjamin Franklin.

PHYSIOLOGY SECRETS IN IMMUNOLOGY

1.which cell is called military intelligence system?
B-lymphocyte.

2.what is virgin B/naive cell?
B cell with fully rearranged IG genes but not yet encountered non-self antigen.

3.what is immunological synapse?
The interaction between TCR and MHC

4.List the main categories of antigen recognition molecule-
TCR,BCR,MHC

5.What is the ratio of T:B?
3:1

BIOSONAR-seeing with sound

                        BIOSONAR: seeing with sound

Echolocation, also called biosonar, is the biological sonar used by several animals such as dolphins, shrews, most bats, and whales. They use their own emitted sounds, along with their auditory systems to perceive and localize objects in their environment. Pulses of emitted sound reflect from objects in the animal’s path and may be interpreted by the auditory system. This ability to localize objects with echoes was termed echolocation.

Human echolocation

 

It is the ability of humans to sense objects in their environment by hearing echoes from those objects. Blind and blindfolded sighted human subjects were in fact able to learn to use echolocation to detect objects in their environement.They actively create sounds ,such as tapping their canes or by making clicking noises with their mouths. Some blind people have described the phenomenon not as a learned method of navigation, but as an inherent and intuitive extra sense. For example, a blind person could walk past a line of trees and feel a “pressure “at their sides as they passed each tree. The cause of this would be the echo of the sound of their footsteps; however they may not consciously be aware of this mechanism, only that the phenomenon exists and can often be relied upon to detect obstacle.

Facial vision

Before it was known to be based on localization of echoes, human echolocation was sometimes described as “facial vision”. It is described as, ability to judge the nearness of bodies by the action of the air against the face.

Two major sets of theories evolved regarding the nature of this sense. One set constituted the tactile or skin sense theory by Diderot in 1749, that the blind were sometimes able to sense, through the skin of their face, some systematic change in subtle properties of nature that alerted them to the presence of objects in their vicinity.

A second set of theories comprised the audition theory which implicated auditory processing as responsible for the perception of objects. These fell in to 2 main classes -the pressure theory which stated that tympanic membrane was sensitive to subtle changes in air pressure caused by the presence of objects, and the auditory theory which asserted that the auditory system can perceive subtle variations in sound waves as they bounce off objects. Thus the term facial vision is little understood phenomenon implying that sensory mechanisms in the face provided some pseudo visual perception of space.

Later the investigators clearly established a definitive relationship between the presence of perceptible sound and the ability to detect obstacles, and they confirmed that no such relationship exists, involving tactile sensation. It was concluded that auditory perception is necessary and sufficient for the detection of obstacles. The perception of  obstacles without vision depends on a rise in the pitch of sounds as they are reflected or echoed from approaching surfaces, and this rise in pitch is only perceptible with frequencies around 10 kHz and above. Since these 3 reports, terms that refer to the perception of echoes -echo detection, echolocation and echo ranging have come in to common use in references to the non visual perception of obstacles by humans.

Mechanism

Vision and audition are close cousins in that both can process reflected waves of energy. Vision processes photons (waves of light) as they travel from their source, bounce off surfaces throughout the environment, and enter the eyes. Similarly the auditory system can process waves of sound as they travel from their source, bounce off surfaces and enter the ears. Both systems can extract a great deal of information about the environment by interpreting the complex patterns of reflected energy that they receive.

3 components must be present for the perception of echoes to take place-sound (an incident wave), a surface or surfaces to reflect sound, and an observer with auditory perception. The quality at which echoes are perceived depends upon characteristics of each of these 3 components and the spatial relationship and interactions among them.

With echoes, a blind traveler can perceive very complex, detailed and specific information from distances far beyond the reach of the longest cane or arm. Echoes make information available about the nature and arrangement of objects and environmental features such as overhangs, walls, doorways and recesses, poles, steps, parked or moving vehicles, trees and other foliage and much more. Echoes can give detailed information about location, dimension, and density. By understanding the quality the nature of the object can be detected.

Echolocation in Bats

 

Bats use echolocation to orient themselves and to locate objects; their auditory systems are adapted for this purpose. This specialization is evident from the inner ear up to the highest levels of information processing in the auditory cortex. Bats have specialized inner ears which allow them selves to hear sounds in the ultrasonic range. The basilar membrane within the cochlea contains specialized neurons for echo information processing. These neurons are specifically tuned to different frequency of returning echoes. Neurons in the inferior colliculus are highly sensitive to time differences, respond even to weak stimuli. Auditory cortex is quite large in comparison with other mammals. The cortex contains series of maps of auditory information, organized systematically based on sound frequency and amplitude. Neurons in these areas respond only to a specific combination of frequency and timing known as combination-sensitive neurons.

Notable individuals who employ echolocation

James Holman

Daniel Kish

Ben Underwood

Dr.Lawrence Scadden

 

 

 

 

 

 

 

 

 

                                                                                                                                  

 

 

                        

 

 

 

 

                                                                                                                                  

 

 

HEART

HEART

In what way might cardiac hypertrophy with pressure overload (resistance training) affect oxygenation of myocardial tissue?

Myocardium depends on an adequate oxygen supply; unlike skeletal muscle this tissue has limited anaerobic energy generating capacity. The important factors that affect myocardial oxygen consumption are the development of tension within the myocardium and its contractility and heart rate. During exercise, with increase in each of these factors, the myocardial blood flow adjusts to balance the oxygen supply with demand.

The myocardial work load can be calculated by using Rate-Pressure Product-RPP-the index of cardiac work.

RPP=SBP (systolic blood pressure) xHR (heart rate).this RPP relates closely to directly measured myocardial oxygen consumption and coronary blood flow.

Aerobic over load training.

The heart mass and volume increases with long term aerobic training. It induces significant adaptations in a variety of functional capacities related to oxygen transport and use. These adaptations also occur in coronary heart disease. Highly trained endurance athletes have larger slow twitch fibers than fast twitch fibers in the same muscle. Slow fibers generate more ATP aerobically which increases the o2 delivery to tissues.

Resistance training (Strength training-Weight training exercises)

Resistance training and upper body exercises produce substantially higher HR and BP and hence high RPPs than more rhythmic exercises with lower body. This added myocardial work causes a risk for coronary heart disease patients with compromised myocardial o2 supply.

Cardiac hypertrophy in hypertension.

Diseases can also induce considerable cardiac enlargement. In hypertension the heart works against after load. (Excessive resistance to blood flow.)This stretches the heart muscle, which, in accordance with Frank-starling mechanism, generates compensatory force to overcome resistance. In untreated hypertension, myocardial fiber stretches beyond the optimal length, dilated heart weakens and unable to deliver enough blood to satisfy minimal resting requirements

Possible explanation

Endurance training produces eccentric hypertrophy-ventricular enlargement. In contrast resistance trained athlete posse’s concentric hypertrophy-thickening of ventricular walls. They do not have volume overload but, elevated arterial pressure. An increase in wall thickness compensates for additional after load on the left ventricle without affecting the cavity size. There is no evidence indicates that specific forms of arduous exercise can damage a normal heart.

A THOUGHT FOR TODAY

"I never teach my pupils;I only attempt to provide the conditions in which they can learn."

                                                                                                              -Albert Einstein

A THOUGHT FOR TODAY

  A THOUGHT FOR TODAY
  “Education is the most powerful weapon which you can use to change the world”
  -NELSON MANDELA

SPECIAL SENSES -SECRETS

  SPECIAL SENSES - SECRETS
1. What is attenuation reflex?

When very loud sound is transmitted through ossicular system to CNS ,reflex is initiated with a latent period of 40 to 80 ms.this reflex causes contraction of tensor tympani muscle which pulls the malleus inward whereas contraction of stapedius muscle which pulls stapes outward. These two opposing effects make the ossicular system very rigid; therefore, it fails to vibrate with the sound wave. Thus, sound is not allowed to enter inner ear (it is attenuated) or its intensity is reduced by 30 to 40 decibels.

2. What is electro-olfactogram?

When an odorous substance gets absorbed on to the olfactory mucosa, electrical changes are setup.Monophasic negative potential is recorded which lasts for 4 to 6 seconds. This recorded response is known as electro-olfactogram.

3. What is purkinje shift?

In bright light ,cones are optimally functioning ,therefore the peak spectral sensitivity of retina is at 560 nm.In scotopic vision only rods are functional ,therefore peak spectral sensitivity of retina is at 500 nm.This shift of peak spectral sensitivity when a person goes from bright to dim light is known as purkinje shift.

4. What is flicker fusion frequency?

Images of any object remain on the retina for some time so that if pictures are shown one after the other, they give an appearance of being continuous. The critical frequency at which fusion occurs is known as flicker fusion frequency. Critical frequency is much higher in bright light.

5. What is the importance of light and dark adaptation?

Sensitivity of retina increases during darkness and decreases during exposure to light. Thus, sensitivity of retina is automatically adjusted to changes in illumination.

SECRETS WITHIN THE HEART

SECRETS WITHIN THE HEART

1. What is law of heart muscle?

It states that the size of the fibers, glycogen content and rate of conduction increases from nodal to purkinje, while length of systole, duration of refractory period and rhythm city increases in reverse order.

2. Which part of the conducting system of heart has longest refractory period at normal heart rate?
Right bundle branch has the longest and bundle of his has the shortest period.

3. What is the normal refractory period in children?

Oneyear-0.11 sec
6years-0.13sec
12years-0.14sec

4. What is Hill’s sign?

In aortic regurgitation, the blood pressure in the leg is higher than the arm. BP increases that is goes “uphill” as the examiner goes down the body.

5. What are neurohemal organs?

Some of the circumventricular organs function as neurohemal organs. (similar to glands but they store their secretary products in a special chamber until stimulated to release it by a signal from the nervous system or another hormone in to the circulation.eg.oxytocin and vasopressin enter the circulation in posterior pituitary and hypothalamic hypophysiotropic hormones enter the portal hypophysial circulation in the median eminence.

6. What is vagal tone?

Impulses from the vagal nerve producing inhibition of the heart beat.SA node displays intrinsic automacity –spontaneous pacemaker activity at a rate of 100-110 action potentials (beats) per minute.(SAnode is predominantly innervated by right vagus)this vagal tone reduces the resting heart rate down to 60-80 beats per minute.

7. What is vasomotor tone?

Under normal condition, C1 area of the VMC transmits signals to sympathetic vasoconstrictor fibers at a rate of half to two impulses per second called sympathetic vasoconstrictor tone. These impulses maintain a partial state of constriction in the blood vessel called vasomotor tone.

8. What is J point?

The point marking the end of QRS complex and the beginning of ST segment .at this point all parts of the ventricles have become depolarized .so no current is flowing around the heart. Therefore, the potential of ECG at this point is zero voltage.

9. What is J wave?

This is rounded rather narrow ‘hump’ like wave usually superimposed on the distal limb of QRS complex and it is due to the early repolarization.Also known as Osborne’s wave occurs in hypothermia.

10. What is central venous pressure?

Pressure in the right atrium is called CVP because all the systemic veins open into the right atrium.

RAYS OF LIGHT

RAYS OF LIGHT

HEART

*The divine is always seated in your heart, consciously living in you.

*It is the heart that has wings, not the head.

*For the mind-knowledge
  For the heart –love and joy
  For the life-power
  For the matter –beauty.

  RAYS OF LIGHT
  Sayings of 
  THE MOTHER

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+