HEART

-

HEART
INTRO: The heart is a cone shaped hollow muscular organ
LOCATION: it is located in the mediastinum which is the space between the two lungs. It lies obliquely, a little more to the left than the right, and presents a base above, and an apex below. The apex is about 9 cm to the left of the midline at the level of the 5th intercostal space, i.e. a little below the nipple and slightly nearer the midline. The base extends to the level of the 2nd rib.

WEIGHT: 250 – 310g

Add caption
Description: C:\Users\FATFEM\Desktop\FCN ACADEMY.PNG
THE DIAGRAMATIC ILLUSTRATION OF THE HEART
ORGANS IN RELATIONS:
Superiorly: the aorta, superior vena cava, pulmonary artery and pulmonary veins
Inferiorly: the apex rests on the central tendon of the diaphragm
Anteriorly: the sternum, ribs and intercostal muscles.
Posteriorly: the esophagus, trachea, left and right bronchus, descending aorta, inferior vena cava and thoracic vertebrae
Laterally: the two lungs

LAYERS
1.     Pericardium
2.     Myocardium
3.     Endocardium

Ø THE PERICARDIUM
The pericardium is the outermost layer and is made up of two sacs which are the
i.                     Fibrous pericardium: The fibrous pericardium is continuous with the tunica adventitia of the great blood vessels above and is adherent to the diaphragm below.
ii.                 Serous pericardium: this layer is further divided into visceral and parietal layers. In between these two layers is a potential space that contains serous membrane which secretes serous fluid called pericardial fluid. Fluid helps to prevent friction during contraction of the heart.
Ø MYOCARDIUM
The myocardium is composed of specialized cardiac muscle found only in the heart. It is striated, like skeletal muscle, but is not under voluntary control. Their cells are arranged in intercalated disc. So that when impulse is initiated, it can spread throughout the myocardium and initiate contraction.
Ø ENDOCARDIUM
This lines the chambers and valves of the heart. It is a thin, smooth membrane to ensure smooth flow of blood through the heart. It consists of flattened epithelial cells, and it is continuous with the endothelium lining the blood vessels.

CHAMBERS OF THE HEART
The heart consists of 4 chambers which are:
Ø The right and left atrium.
Ø The right and left ventricles.
NOTE:
*The right side of the heart is separated from the left side by the SEPTUM
*The atrium and the ventricles are separated by the atrio-ventricular valves
*Blood in the left side of the heart is always oxygenated.
*Blood in the right side of the heart is always deoxygenated.

VALVES OF THE HEART
The heart has two type of valves which are the
Ø Semilunar Valve (the aortic valve covering the Aorta and the pulmonary valves covering the pulmonary trunk)
Ø Atrio-ventricular valves this are the right and left atrio-ventricular valves which are found between the atria and the ventricles.
NOTE:
*The right atrio-ventricular valve is otherwise known as the Tricuspid valve
*The left atrio-ventricular valve is also known as the Bicuspid valve
*The left atrio-ventricular valve is also known as the Mitral Valve

BLOOD SUPPLY TO THE HEART
Ø Arterial supply is by left and right coronary artery
Ø Venus drainage is by the coronary sinuses
NERVE SUPPLY
The Nerve supply of the heart is by the sympathetic and the parasympathetic nervous system.

BLOOD FLOW THROUGH THE HEART
There are 2 types of circulations in the heart. This are:
Ø The pulmonary circulation
Ø The systemic circulation

PULMONARY CIRCULATION
This is a type of circulation between the heart and the lungs in order to get the blood oxygenated and to remove waste product like CO2 from the blood. In this study, we are going to describe this in steps.
STEP 1: blood enters the right atrium through the superior vena cava, the inferior vena cava, and the coronary sinuses.
STEP 2: the right atrium contracts, the Tricuspid valve opens and pump blood into the right ventricle.
STEP 3: the right ventricle contract, Tricuspid valve closes; the pulmonary valve opens and pump blood into the pulmonary trunk.
STEP 4: the blood in the pulmonary trunk enters into the right and left pulmonary artery. These arteries carry blood to the lungs for oxygenation.
STEP 5: After oxygenation, the blood is drained back to the heart by the pulmonary veins which drains into the left atrium. This ends the pulmonary circulation.
Description: C:\Users\FATFEM\Desktop\PULMONARY CIRCULATION.PNG

SYSTEMIC CIRCULATION
The systemic circulation starts by the contraction of the left atrium forcing the Bicuspid valve to open and pump blood into the left ventricles. As the left ventricles contract the Bicuspid valve closes, the aortic valve opens and blood is pumped into the aorta. This circulates blood to every part of the body systems, Hence the name systemic circulation.

Comments

Post a Comment

Popular posts from this blog

ANATOMY OF THE EYE

-
Image
Special senses  [ EYE] These are organs in the body that performs specialised functions. They contain sensory receptors which receives sensory impulses and pass them to the appropriate centers in the brain for interpretation.   ➡️ Types of Sensory Receptors - based on the type of stimuli they detect: 1. Mechanoreceptors - pressure receptors, stretch receptors, and specialized mechanoreceptors involved  in movement and balance.  2. Thermoreceptors - skin and viscera, respond to both external and internal temperature.  3. Pain receptors - stimulated by lack of O2, chemicals released from damaged cells and inflammatory  cells.  4. Chemoreceptors - detect changes in levels of O2, CO2, and H+ ions (pH) as well as chemicals that  stimulate taste and smell receptors  5. Photoreceptors - stimulated by light ➡️ Distribution of Receptors in the body: Special Senses • mediated by relatively complex sense organs of the head, innervated by cranial ...
Read more

VENTRICLES OF THE BRAIN

-
Image
 The ventricular system is a set of communicating cavities within the brain. These structures are responsible for the production, transport and removal of cerebrospinal fluid, which bathes the central nervous system. FUNCTIONS OF CEREBROSPINAL FLUID  Cerebrospinal fluid is an ultrafiltrate of plasma that surrounds the brain and spinal cord. It serves three main functions : ➡️ Protection : acts as a cushion for the brain, limiting neural damage in cranial injuries. ➡️Buoyancy : by being immersed in CSF, the net weight of the brain is reduced to approximately 25 grams. This prevents excessive pressure on the base of the brain. ➡️Chemical stability : the CSF creates an environment to allow for proper functioning of the brain, e.g. maintaining low extracellular K+ for synaptic transmission. VENTRICLES OF THE BRAIN  The ventricles are structures that produce cerebrospinal fluid, and transport it around the cranial cavity. They are lined by ependymal cells, which fo...
Read more