What To Do If Your Testicles Hurt

Urinary Anatomy and Physiology of Heart Joints

The heart is the muscular pump that provides the energy needed to move blood through the blood vessels (2). It is roughly the same size as your fist, but not the same. It measures about 12cms long, 9 wide, and 6 thick. It has an average weight of 250g and 300g in adult women and men respectively (a) (2).

This organ is located in the mediastinum, a mass of tissue extends from the sternum to the spine and between the lungs (1). Rests on the diaphragm and two thirds are to the left of the midline of the body.

Location Taken Heart
Anatomy Physiology and Surgery, Dr. Miguel Noguera
http://mignog.ar.tripod.com/clases/pleura3.html

pericardium and heart wall layers

The heart is surrounded by a membrane called the pericardium (a) (2), whose function is to keep the body in position while granting freedom movements for rapid and vigorous contraction (1). The pericardium is divided into two parts:

• Fibrous Pericardium: superficial part consists of connective tissue, dense, regular, very elastic and resilient.
• Serous Pericardium: from deep, thin and delicate. It is divided into the parietal layer, which fuses with the fibrous pericardium and the visceral layer, also called the epicardium.

pericardial fluid secretion is a lubricant which is located between the parietal layer and visceral layer. Designed to reduce friction as the heart does beat. The space containing the liquid is called pericardial cavity (1) (2).

heart wall, located inside the pericardium, is divided into three layers: the epicardium, myocardium and endocardium. The epicardium, as indicated above is known as the visceral layer of serous pericardium consists of connective tissue. The myocardium is heart muscle tissue and is responsible for the heart's pumping action. The innermost layer is the endocardium is a thin layer of endothelium overlying a thin layer of connective tissue (1) (2). Heart Chambers



The heart has four chambers. The two upper chambers are called atria or atria and two lower chambers are called ventricles. Each one of them is filled with blood at any given time. In the front of each atrium is a structure similar to a bag called atrial appendage. They increase slightly the capacity of the atria, allowing you to receive a greater volume of blood. On the surface you can see the coronary sulcus (surrounds most of the heart) and the anterior and posterior interventricular grooves that mark the divisions between left and right ventricles. (1)

Scheme with parts of the heart
Taken from the blog fourth thistle
http://cuarto-cardal.blogspot.com/2007/09/el-corazn-sus- partes.html

The atrium or right atrium receives blood from the superior vena cava, the inferior vena cava and coronary sinus (1) (2). The back wall is smooth while the trabeculated anterior wall is due to the presence of muscles pectinal, also seen in the right atrial appendage. Between the two atria is a thin wall called the interatrial septum. The blood passes from the right atrium to right ventricle through a tricuspid valve is called. This valve, like the others that will be mentioned later, is composed of dense connective tissue covered by endocardium. (1)

The right ventricle way most of the front of the heart (1) (2). Internally it contains a series of reliefs consisting of cardiac muscle fiber bundles called fleshy trabeculae. The tricuspid valve is connected to structures called chordae which in turn are connected to the papillary muscles. The right and left ventricles are separated by the interventricular septum. Blood passes from the right ventricle to the pulmonary trunk through the pulmonary valve. Their final destination is the lungs, where blood is oxygenated and then head to the left atrium through the pulmonary veins.

The atrium or left atrium form most of the base of the heart (1). Unlike the right atrium, it contains only pectineus atrial appendage (1). The blood enters the left ventricle through the mitral or bicuspid valve.

Diagram atrium and left ventricle
Taken from the site of Mitral Valve Repair Center
http://www.reparacionvalvularmitral.org/content/view/56/

The left ventricle forms the apex or apex of the heart (1). As the right ventricle, and strings containing fleshy trabeculae tendon connecting the mitral valve papillary muscles. When blood leaves the left ventricle, passing through the aortic valve into the ascending aorta. From this artery leaves the irrigation for the entire body, including the coronary arteries supplying the heart.

the tricuspid and mitral valves are called or auricoventriculares atrioventricular (AV). Pulmonary and aortic valves are called semilunar valves.

The muscular wall of the left ventricle is considerably thicker than the right because it must do more intensive work: to pump blood to more distant areas like the head and lower limbs (1).

Pulmonary and Systemic Circulation

The heart pumps blood in two closed loops: the general systemic circulation or pulmonary circulation (1). The left side of the heart is the systemic circulation pump receives oxygen-rich blood from the lungs and ejects into the aorta. All organs receive blood through the artery except the lungs, which receive blood from the pulmonary circulation.

The right side of the heart is the pulmonary circulation pump, which receives oxygen-poor blood from the bodies and sent to the lungs to release carbon dioxide and oxygen reload.

Driving System

The heart has a network of specialized cardiac muscle fibers called automatic fibers. They are in charge of the intrinsic electrical activity and rhythm that allows the heart beating. These fibers generate action potentials in a repetitive and these in turn trigger heart contractions (1). It is generally said to have two important functions (1):

• Act as determining the rate of pacemaker electrical excitation
• Driving up the system for each excitation progress through the heart

Propagation of Action Potentials
Taken from youtube.com
http://www.youtube.com/watch?v=EgmyF5nKKEA

cardiac action potentials propagating along the conduction system as follows (1) (2):

1. begin in the sinoatrial node or sinoatrial (SA) , located in the right atrium just below the opening of vena cava superior.
2. It spreads through both atria through of gap junctions in the intercalated disks (1). Internodal pathways using anterior, medial and posterior (4).
3. Thanks to this action potential, both atria contract.

to 0.03 seconds have elapsed here

4. The action potential reaches the atrioventricular node , located in the atrial septum.
5. Here the impulse is delayed 0.09 seconds to ensure that the ventricles are completely filled.
6. It spreads through the His Bundle or atrioventricular bundle found in the interventricular septum. It has two branches, one right and one left for each the ventricles. This part of the process takes 0.04 seconds.

to 0.16 seconds have elapsed here

7. After spreading along the Bundle of His (both branches), the action potentials reach the Purkinje fibers , causing the contraction of the ventricles.

As you can see, the sinoatrial node is the main pacemaker of the heart. The fibers of this node initiate an action potential every 0.6 seconds (100 times per minute) (1) and although the autonomic nervous system and certain hormones can modify the frequency and strength of each beat, the rhythm is still maintained by the node sinoatrial. (1)

auricoventricular Node ritmogénico also has potential, so it can also act as a pacemaker if there are flaws in the sinus node. The bundle of His has the same feature, which could also assume that work if necessary (5).

cardiac cycle

The cardiac cycle is defined as the set of events that occur in heart muscle between beats and other (4). The atria and ventricles alternately contract and relax the blood moving through the chambers or to the aorta and pulmonary trunk. It is divided into two phases (4):

• diastolic rejalación: in which the atrium or ventricle fills with blood.
• systole or contraction, in which the atrium or the ventricle eject their blood.

diastole is said that is a passive process (which does not consume energy) while the systole is an active process where myocardial fibers waste energy (5).

Cardiac Cycle: Systole and Diastole
Taken from youtube.com
http://www.youtube.com/watch?v=jLTdgrhpDCg

The atrial systole occurs when the atria contract tools that the ventricles are relaxed (1). As noted above, this contraction occurs as a result of the action potential initiated by the sinoatrial node. During this process move 25 ml of blood filling the ventricles finish (1). Importantly, passed 105 ml of blood from the atria to the ventricles during rapid filling phase just before atrial systole. Both atrioventricular valves (tricuspid and mitral) are open at this time. Parallel to this process is occurring at the ventricular diastole .

The ventricular systole occurs when the ventricles contract while the atria relax (1). This contraction occurs as a result of the action potential that travels through the Bundle of His and Purkinje fibers. The pressure within the ventricles rises and the atrioventricular valves are closed. For about 0.05 seconds, both semilunar valves and the atrioventricular are closed. This is called isovolumetric contraction (1) (4).

When right ventricular pressure rises above pulmonary artery pressure (20 mm Hg or so) and left ventricular pressure rises above the pressure of the aorta (80 mm Hg approximately), semilunar valves open and blood flows out of the heart (1). Some authors argue that the pressures to open the semilunar valves is 120 mm Hg to 80 mm Hg aortic and pulmonary (4). Parallel to this process is occurring at the atrial diastole .

When most of the blood has been expelled, the blood in the aorta and pulmonary trunk tends to return and this results in the closure of the semilunar valves.

During ventricular isovolumic contraction, the atria begin to fill with blood again waiting for the opening of the atrioventricular valves. When the amount of blood exceeds certain limit, the tricuspid and mitral valves open and rapid ventricular filling begins. This is the beginning of the next cycle (1).


To read more:
(1) Tortora, Gerald. Derrickson, Bryan. 2006. Principles of Anatomy and Physiology. 11 th. Edition. Editorial Médica Panamericana. Mexico DF. Mexico. Cap 6.

(2) Bulls, Avelina. Cardiovascular System. Virtual infermeria. Barcelona, \u200b\u200bSpain.
Available online:
http://www.infermeravirtual.com/ca-es/activitats-de-la-vida-diaria/la-persona/dimensio-biologica/sistema-cardiovascular-sistema-limfatic/pdf/sistema -cardiovascular.pdf

(3) Anonymous. Lab Guide. Department of Physiological Sciences. Pontificia Universidad Javeriana. Bogotá, Mexico.
http://fisiopuj.tripod.com/Guias/n_ventricular.pdf

(4) Montalvo Diago, Jane A. Anthology of Human Physiology. American University. San Jose, Costa Rica.

(5) Bustos, Jorge. The heart as a pump, the cardiac cycle and arousal rhythm of the heart. American University. San Jose, Costa Rica.