Human heart

Human Heart.


Depending upon the mode of contraction there are two kinds of hearts:
Myogenic hearts: The hearts in which the wave of contraction starts in the muscle fibre of heart are said to be myogenic hearts. Eg. Human Heart.
Neurogenic Heart: The in which the contraction wave takes its origin from its nerve cells of group of such cells are said to be neurogenic hearts. Eg. Frog’s heart.
Structure if Human Heart.
A Human Heart is a triangular and muscular organ located in thoracic cavity between the lungs. The human heart is about 12 cm in length and 250gms in weight.
External structure of Human Heart
Human Heart is a conical muscular organ, enclosed and protected in a double chambered wall called pericardium. The cavity between two pericardial membrane s filled with pericardial fluid that prevents the heart from shocks, mechanical injury and also allows free movements of the heart.
Human Heart is a four chambered organ, having two auricles and two ventricles. Right auricles and right ventricles that deals with the impure blood whereas the left chamber is for pure blood. There is no mixing pure and impure blood inside or outside the heart.
The external structures of Human Heart are:
Auricles: Auricles are thin walled chambers. The left auricle is smaller than the right auricle, Right auricle receives impure blood from the superior venacava and inferior vanacava. Whereas the left auricle receives pure blood from the two pulmonary veins.
Ventricles: Ventricles are thick walled. The left ventricle is somewhat longer and about three times thicker than the right ventricle. Right ventricle receives impure blood from the right auricle and left ventricle receives pure blood from the left auricle.
Pulmonary trunk and aorta: The pulmonary trunk arises from the right ventricle. It divides into ledt and right pulmonary arteries that carry deoxygenated blood to the lungs. Similarly an aorta arises from the left auricle, This gives off three branches namely: Innominate, left common carotid and left subclavian.
Internal structure of Human Heart.
Auricle: Auricle are thin walled chambers separated by inter auricular septum.The opening of the venecave that provided impure blood to the right auricle is guided by Eustachian valve.
Bicuspid and tricuspid valves: The auricles and ventricles are separated by the auriculo-ventricular septum. Each auricle opens into its corresponding ventricle through an auriculo-ventriculo aperture. These apertures are guarded by flaps or valves which opens only in the ventricle and prevent the back flow of the blood . The left auriculo-ventricular aperture is guared by bicuspid valve or mitral valve. Similarly the right auricular structure is guared by tricuspid structure. These valves are attatched to the walls of the ventricles by the help of tendons of fibrous chords called chordae tendinae. Its main function is to hold the flaps.
Ventricles: Ventricles are thick walled, separated by thick and oblique inter-ventricular septum. The walls of ventricles have many muscular ridges or projections called columnae carnae. IT divides the cavity of ventricles into smaller spaces, known as fissures. Right ventricle receives the impure blood whereas the left ventricle receives pure blood. Due to the contraction of ventricles, the blood is pumped forcefully to the different parts of the body.

Circulatory system

Circulatory System.
Introduction
All the parts o the body needs constant supply of nutrients, oxygen etc. along with other required minerals for the metabolic activities to take place. For this purpose some extra cellular fluids are are continuously flowinf through the body all the time, this fluid is called blood. And the flow of blood is called circulation and the structures and organs which are involved in theis process are called circulatory system.
This helps in balancing a favourable internal environment inside the body, this process is called homeostatis.
Functions of Circulatory system:
Circulatory system helps in the transport of gases
Transportation of O2 from respiratory surface to tissues and CO2 from the tissues to the respiratory surfaces through circulatory system
Circulatory system transport of metabolic waste products
circulatory system transport various metabolic wastes produced from different tissues from which they are transported to arous organs so that they can be removed out of the body
Circulatory system transport of digested food substances
circulatory system absorps and transports digested food from the site of absorption to the different organs of the body of storage, oxidation or synthesis etc
Circulatory system transport of chemical messengers
circulatory system transports the chemical messengers like hormones from the site of their origin to the target organs
Circulatory system helps in tempreture regulation
circulatory system regulates the body tempreture by distributing the heat produced in one part of the body to different parts there by equalizing the body tempreture
Circulatory system helps in transport of metabolic intermediates
The fluid present in the circulatory system carries the various intermediate compounds produced in metabolic reactions from one tissues to another for further metabolism.
Circulatory system helps in protection against the diseases.
The circulatory system produced phagocytic leucocytes that engulf and kill harmful micro organisms.

Evolution

What is Evolution?

The answer is, it the development of the organism in which it diverges and gives off different species.
The main requirements for evolution are

• Environment
• Time
  
• Organisms

Who is the Father of founder of Evolution?
It is Empedocles, and it was Buffon who carried on the further studies.Even after the foundation of Evolution, this term was not particularly used thus Evolution was first used by Herbert spences

Evolution can be of two types

1. Organic evolution:

The changes in living beings is called organic evolution. The father of organic evolution is Charles Darwin. ITs characteristics:

• Or. Evolution is slow but continuous process





• Or. Evolution brings changes in organisms over time to time

2. Inorganic evolution:

The changes in non-living beings it is called inorganic Evolution. BUt is merely used.

Evolution accepts Descent with modifications that is new characters and modifications are seen in offsprings.

Factors supporting Evolution:

Homologous organs:

The organs present in different species are called homologous organs if they are structurally same but different in their functions and characteristics. Some examples of Homologous organs are:

• Limbs of diffrent vertebrates such as hand of man, leg of horse, wing of bird, patagium of bats, flipper of whale. Though they are structurally same thier functions are different. All of their arrangements are in the order as such: Humerous, radius, ulna, carpels, metacarpels and phallenges. All of the above mentioned organisms posses the same struture but their functions are grasping, sprinting, flying, flying and swimming repectively. This supports DIVERGENT EVOLUTION that is even if the structure and origin of appendegases are same they diverge thmselves for different functions.Mouth parts of insects also belongs in this category. Remember the mouth parts of insects are same but they perform different functions such as in butterfly(sucking), mosquito (biting), bee (chewing ).





• Teeth of organisms have similar origin and structure., they are generally arranged in the pattern I C P M - 2 1 2 3.





• Thorns of Bouganivillea & tendrils of cucurbits are almost similar in structure and origin but the thorns in Bouganivillea helps in protection and the tendrils helps for the climbing.





• Ovaries & Testes, Penis & Clittoris, Finof fish and wings of birds. All of these organs have similar structure but different funtions





• Leg of different insects

Analogous organs:

These are the organs having similar functions but different structures. This also supports Evolution. Some examples are

• Wings of insects and wings of birds. They have different structures but similar functions for flying. This supports CONVERGENT EVOLUTION.





• Eyesof squids and eyes of fishes. Their structures are different.





• Sting of Honey bee and sting of scorpians. The Sting of Honeybee is ovipositor that is originates from the part of the body used for the storage of eggs whereas the sting of scorpians are originated from the abdominal cavity.





• Trachea of insects and other animals are vastly different from each other in structure but both of them help in the process of respiration.





• Crustaceans and fish both possesses gills but their structure is different but their funtion is same.





• Fin of fish and flippers of whale are never alike. BUt both of them help in swimming.





• Stem of Ruscus helps in photosynthesis whereas other plant do this through leaf.

Bohr's atomic model

Simple concept about Bohr's atomic model

Here is very simple concept about Bohr's atomic model:

Well, Bohr's atomic model talks about what happens when an electron revolves round a nucleus.
Bohr's atomic model says that when an electron revovles round a nucleus it revolves in an certain orbit having defined energy. There are many orbits surrounding the nucleus. the nearest orbit has the lowest energy and the farthest one has the the highest enegy. That means electron can't revolve in random order otherwise they may collide and along with this Bohr's atomic model also says that electron has certain amount of energy stored in it.
Bohr's atomic model terms that electrons can only revolve in those orbits where the energy of the electron and the energy of the orbit gets matched. Bohr's atomic model says that the energy of these orbits are multiples of (see the image) .Now an electron can't move in a definate orbit all the time, while moving it either gains energy or looses energy. Bohr's atomic model assures that when an electron looses energy it jumps to a lower orbit and when it gains energy it jumps to a higher one.
This is the major concept.

Bohr's atomic model gives the value of the velocity of the electron that moves around it.
As the electron moves in circular path it needs a force which keeps it inside the orbit. This force is Centripetal force.








So how does the electron gets centripetal force, it is the coulomb force that provides the necessary centripetal force.
Now coulomb's force is the required centripetal force, both must be equal then.





















Bohr's atomic model also gives the relation that the angular momentum of the electron moving in an orbit is equal to nth times the plancks constant where n refers to the number of orbit.

Newton's laws of motion

Newton's Laws of motion

Sir Isaac Newton was one of the greatest scientists and mathematicians that ever lived.Born in England on December 25, 1643.
He stdied in Trinity College Cambridge.While at college he became interested in math, physics, and astronomy. Newton received both a bachelors and masters degree.
Newton had ideas about gravity, the diffraction of light, and forces.
He died at the age of 87, but before that he proposed the most popular theory "Newton's laws of motion"
Newton's laws of motion(1st law)
1st newton's laws of motion stats that everybody in the universe continues its state of rest or motion until and unless an external force is applied on it. This newton's laws of motion says that if a ball is kicked and if their is no force to stop then it will never stop and go round and round the earth. A moving car can revolve round the earth if no brakes a re applied.
But this doesnt happen because of opposing forces such as frictional forces and gravitational forces and other opposing objects such as stones bricks etc.
Newton's laws of motion (2nd law)
We know about speed. But this Newton's laws of motion talks about acceleration.
Acceration of a body is defind as the ability of the body to gain speed at a particular time. That means if a body has accelaration 10m/s(i/e Meters travelling per second) then every second its speed increases by 10m/s.
Ths Newton's laws of motion says that greater the mass or weight of the body greater will be the force needed for it to move.
For example more force will be needed to kick a light ball, but greater amount of forece will be needed to move a wall.
Newton's laws of motion(3rd law)
This Newton's laws of motion states that to every action there is an equal and opposite reaction.
Simply if we open up a filled ballon then ballon moves in the direction opposite to the flow of air.This is as the walls of the ballon pushes the air out of the ballon, the air also pushes the ballon away from it.
This newton's laws of motion is applicable to all body in the universe.

What is science?

According the books and the notes "Science is defined as the study of things visible and non-visible things around us.".. But in my own words science is the reason for what happens around us.
Science teaches us about the possiblities of the particular thing to happen. An apple falls from a tree, science gives the reason why it falls. Rocket flies into the space, science says its because of action and its equal reaction. We breath we eat we walk we talk every reason is given by science.
Generally science is divided into 3 topics.

• Physics
• Chemistry
• Biology
  

Physics deals with the measurements and physical causes.
Chemistry deals with the reactions of the chemical compounds to give a specific product.
Biology deals with the study of life and living beings.