Study of Heart.

Hello, Friends, I'm Sofiya, I m going to start the class Bio So please friends support me and follow me here now let's start our class with the topic of heart.

firstly we are going to familiar with some important terms about the heart.

•              weight of heart -   300-310 gm (in a male)

                                               - 225-250 gm(in female)

•  heart measures- 12 cm(l)9 cm(w)6 cm(thick).

• The upper part of the heart is known as the base and the lower part is known as the apex
• the base of the heart is formed by LEFT AND RIGHT ATRIUM.

• APEX of the heart is formed by the left ventricle.

• the thinnest wall of a chamber of the heart-right atrium.

• The heart is found in the thoracic cavity.

• 75%of the heart situated on the left and 25% in right.

• The heart is made up of cardiac muscles which are involuntary muscles.

• blood vessels that carry blood away from the heart are the artery.

• Blood vessels which carry blood to the heart are vain.

• Blood vessels which link arteries and vein are called capillary.

• The Pulmonary is the only artery in the human body that carries deoxygenated blood.

• The middle layer of the heart is known as MYOCARDIUM.

HEART


The heart is a conical, hollow muscular organ. It lies in the thorax b/w LUNGS and behind the STERNUM. It is about 10 cm long and weighs about 300 gm. Bases of the heart is above and the apex is below.
POSITION OF HEART
The heart lies in the THORAX between the lungs and behind the STERNUM two-third of the heart is on the left side. It lies obligingly. It is directed more towards the left side than one right side. The apex of the heart lies at the level of the 5th intercostal space,9 cm to the left of midlife. the base extends.

Pulse and sound produced by the heart

Totally four sounds are produced by the heart -the first sound is LUB and the second sound is DUB can be heard by a stethoscope. The third and the four sounds can not be heard.

FIRST SOUND

It produced by the closure of the artery ventricular valve (aortic pulmonary). It shrill and short duration.

SECOND SOUND

It is produced by the closure of semilunar valves (aortic and pulmonary). It is also shilled and of short duration.
Pulse is a thrifting sensation felt over the wall of arteries. It is defined as the pressure difference transmitted in the form of a wave over the arterial pulse rate that is almost the same as heart rate (60 to 80 /min). The wrist is the common site where the pulse is usually felt. At this site, the radial artery is very super facial. This pulse is called a radical pulse other arteries where the pulse can be felt are the carotid artery, facial artery, and temperature artery. In case of fever the rate of pulse increases at the rate of 10/every rise of 1farenhiet.
Generally, veins do not exhibit pulsation. The only vein which exhibits pulsation is the jugular vein(which never to the heart). Pulse is an alternate expansion (rise) and recoil (fall) of an artery as the wave of blood is forced through it during the contraction of the left ventricle. The pulse can be felt by the fingers on a point where an artery crosses a bone close to the surface of the skin. 
When the left ventricle contracts, it forces about 70 ml of blood into the aorta and into the arteries. The walls of the arteries being elastic, expand as an added amount of blood is forced into them. The arteries relax as the wave of blood passes, only to expand again with the next wave of blood. This expansion and recoil of arteries is the pulse and serves as an indication of the frequency of the heart rate.