Human Circulatory System, Std- 10

Human Circulatory System

➨The organ system of human beings which is responsible for the transport of materials inside the body is called circulatory system.

➞ it consists of the heart, arteries ,veins, capillaries and blood.

Heart - The Pumping Organ

➞ it is a muscular organ in human body, which is made up of special type of muscles known as cardiac muscles.
➞ it is roughly Triangle in shape and its size is about as same as our clenched fist.
➞ it is located between the lungs in the thoracic cavity.
➞ Its measure is about:-
                                        Length - 12 cm
                                        Breadth - 9 cm.
➞ it is enclosed in a double layered membranous sac called pericardium.

➡ Pericardium protects the heart from injury.

 External structure of the Heart

➜ it is four chambered organ divided by Septa into two halves,
  (i) The right halves ,
                                     It consists of Right auricle or atrium and right ventricles.
  (ii) The left halves,
                                 It consists of Left auricle and left ventricle.

     

  ➤   Internal structure of the heart.

  ➞ internally heart is divided into four Chambers,
                  ! Two auricles &
                  !! Two ventricles

➤ Auricles
:- These are thin walled chambers and separated by an inter-auricular septum .

➞ Number - 2,
   ( Left and Right auricles/atrium).
➞ it is also known as Atria.
➞ These are the receiving Chambers of the heart which means they receive blood ( oxygenated blood ) from the main veins.
➞ The left Atrium is connected to the left ventricle and similarly the right Atrium is connected to the right ventricle through Valves.

 ➤ Ventricle

:-These are thick walled chambers which are separated by an inter-ventricular septum.

:- They are also known as the discharging chambers of the heart.

  ➤ The Blood Vessels

➞The blood vessels that enter or leave the heart are called  blood vessels.
:- They also known  as the great blood vessels of the heart.

➞ It includes ,
         * Superior (Anterior ) Vena cava
         * Inferior (Posterior ) Vena
         * Pulmonary Artery
         * Systemic Aorta

  ➤ Apertures and Valves in the Heart

➞There are mainly four valves in the heart which control the flow of blood within the heart.
➞it includes,

1. The Bicuspid Valve

➞ It guards the opening of the left auricle into the left ventricle.

➞ it is also known as Mitral valve.

2. The Tricuspid Valve

:- It guards the right auriclo-ventricular aperture.

3. Pulmonary Valves

➞ They are present at the base of aortic and pulmonary arches.
➞ These Valves check the back of blood into the ventricles .

4. Aortic Semilunar Valve

➞ It is present at the point of origin of Aorta from the left ventricle.

➤ Circulation of Blood through the Heart

 Double Circulation
:-The flow of blood twice through the          heart in each circuit is called Double Circulation.

:- It occur in human beings.