Cardiovascular System

Wonder how heart pumps blood? How blood is transferred to different parts of your body and how important Cardiovascular System is? Well ill be going to explain this for you.



Cardiovascular system is composed of Heart – the organ that pumps blood through the system, Blood – connective tissue that has plasma and a variety of cells and substances and Blood Vessels – a network of passageways to transport the blood to and from the body’s cells

Blood vessels are intricate networks of tubes that transport blood throughout the entire body. There are different Walls often called coats or tunics. The Tunica interna is the innermost layer, composed of squamous epithelial cells, provide smooth surface so blood can easily pass through. The Tunica media, the middle layer, thicker and are composed of smooth muscles and elastic tissues and collagen. And the Tunica externa which is outermost layer provides vessel support and protection, composed of fibrous tissue.

There are different blood vessels namely Arteries, Aorta, Arteriole, Capillaries, Venules, and Veins. Arteries are an elastic blood vessel that transports blood away from the heart. Aorta is the largest artery in the body, originating from the left ventricle of the heart and extends down to the abdomen, where it branches off into two smaller arteries. Arteriole is a small diameter blood vessel in the microcirculation that extends and branches out from an artery and leads to capillaries. Capillaries are where the change of nutrients, gasses and waste products occurs at the cellular level. Venules are ever merging vessels and the tiniest which forms the larger veins. Veins are an elastic blood vessel that transports blood from various regions of the body to the heart. Veins also have thinner walls than arteries, are more numerous, and have a larger capacity to hold blood.

The Heart is a specially shaped muscle that contains series of chambers that move through out the body. The base of the heart is proximal to your head, while the apex is distal. It is a Single organ that acts as a two separate pumps working together. The right side is responsible for collecting the blood and sending it to lungs to pick up oxygen and get rid of carbon dioxide. The left side collects blood from the lungs and pumps it throughout the body.


Pericardium is the fluid filled sac that surrounds the heart and the proximal ends of the aorta, vena cava, and the pulmonary artery. It is divided into three layers: Endocardium is the inner layer of the heart. It consists of epithelial tissue and connective tissue. Myocardium is the muscular middle layer of the wall of the heart. It is composed of spontaneously contracting cardiac muscle fibers which allow the heart to contract. And Visceral Pericardium is the outer layer of the wall of the heart. It is composed of connective tissue covered by epithelium. The epicardium is also known as the visceral pericardium. Pericardial Cavity lies between the visceral pericardium and the parietal pericardium which is filled with pericardial fluid which serves as a shock absorber by reducing friction between the pericardial membranes.

There are different Chambers of the Heart. Atria contains the upper two chambers of the heart are called the left atrium and the right atrium. Ventricle contains the lower two chambers of the heart. The wall that separates the two smaller chambers (atria) is called interatrial septum. The wall that separates the two larger chambers (ventricle) is called interventricular septum.

Vena cava is the two largest veins in the body. They carry de-oxygenated blood from various regions of the body to the right atrium. Superior Vena Cava brings de-oxygenated blood from the head, neck, arm and chest regions of the body to the right atrium. Inferior Vena Cava: brings de-oxygenated blood from the lower body regions to the right atrium.

Heart Valves are flap-like structures that allow blood to flow in one direction. There are different valves, the bicuspid valve, tricuspid valve, aortic valve, and pulmonary valve.

Cardiac cycle is the sequence of events that occur when the heart beats. The cardiac cycle is divided into two: Diastole and Systole. Diastole is part of the cycle which Ventricles are relaxed, Atrioventricular valves are open, The sinoatrial (SA) node, which starts cardiac conduction, contracts causing atrial contraction, the atria empty blood into the ventricles, and Semi lunar valves close preventing back flow into the atria. On the other hand, Systole is part of the cycle which Ventricles contract, atrioventricular valves close and semi lunar valves open. And Blood flows to either the pulmonary artery or aorta.

Autorhytmicity is the unique ability of the cardiac muscles that they don’t rely on nerve impulses and hormones to contract because they can contract on their own. Step 1: Pacemaker Impulse Generation - SA node contracts generating nerve impulses. Step 2: AV Node Impulse Conduction - Impulses are delayed for about tenth of a second this allows the atria to contract and empty their contents first. Step 3: AV bundle Impulse Conduction - The bundles branches off into two and the impulses are carried down the center of the heart to the left and right ventricle. Step 4: Purkinje Fibres Impulse conduction- AV bundles divides into Purkinje fibres in the ventricles to contract
The function of the Blood is to transports dissolved gases, Waste products of metabolism, Hormones; Enzymes; Nutrients , Plasma proteins, Blood cells (incl. white blood cells 'leucocytes', and red blood cells 'erythrocytes'), maintain Body Temperature, control, remove toxins from the body, regulate Body Fluid Electrolytes, help to protect us from the invasion and infection by pathogens and toxins.

Erythrocytes (Red blood Cells) RBCs are created by the red bone marrow through a process called hemopoiesis. It performs two crucial functions: transports oxygen from the lungs to the cells in the body with the aid of an iron-containing red pigment called haemoglobin and help to transport carbon dioxide, a by-product of cellular metabolism, from the cells to the lungs for removal from the body.

Leukocytes (White blood Cells) WBCs are guardians from invasion and infection. The types of WBC’s are Polymorphonuclear granulocyte and Agranulocyte. Polymorphonuclear granulocyte composes Neutrophils, Basophils and Eosinophils. Agranulocyte composes of Monocytes and Lymphocytes.

Thrombocytes (Blood Platelets) are the smallest formed elements. It is responsible for the bloods ability to clot and it releases serotonin which can cause smooth muscle constriction and decreased blood flow.

Special Senses

Everything we know about the world comes to us through our senses. Usually, we were thought to have just five of them—sight, hearing, touch, smell, and taste. Scientists now recognize that we have several additional kinds of sensations, such as pain, pressure, temperature, joint position, muscle sense, and movement, but these are generally included under "touch."


The first sense that ill be going to discuss is the Eye. There are External structures of the eye. Lacrimal apparatus includes a series of ducts and the lacrimal glands that produce tears, which washes and lubricates the eyeball. Eyelids protect the eyes associated with eyelids that prevent gross particles to enter the eye. The conjunctiva is a mucous membrane that covers the anterior eyeball and lines the eyelids. The sclera is the outer, tough, protective layer. Its anterior portion is the cornea, which is transparent to allow light to enter the eye. The choroid is the middle layer, which provides nutrition to the internal eye structures and prevents light's scattering in the eye. Anterior modifications include the iris which controls the size of the pupil). The retina is the innermost layer, which contains the photo pigments. Rods are dim light receptors. Cones are receptors that provide for colour vision and high visual acuity. The fovea centralis, on which acute focusing occurs contains only cones. The blind spot (optic disk) is the point where the optic nerve leaves the back of the eyeball. The lens shape is changed by the ciliary muscle for close focus. Anterior to the lens is the aqueous humour; posterior to the lens is the vitreous humour. Both humours reinforce the eye internally. The aqueous humour also provides nutrients to the lens and cornea. Errors of refraction include myopia, hyperopia, and astigmatism. All are correctable with specially ground lenses.


Next to be discussed is the sense of hearing. The ear is divided into three major areas. Outer ear structures are the pinna (auricle), external auditory canal, and tympanic membrane (eardrum). Sound entering the external auditory canal sets the eardrum into vibration. Middle ear structures are the ossicles and auditory tube within the tympanic cavity. The ossicles are malleus, incus, and stapes which transmit the vibratory motion from the eardrum to the oval window. The auditory tube allows pressure to be equalized on both sides of the eardrum. These structures are also involved with sound transmission only. Inner ear, or bony labyrinth, consists of bony chambers namely cochlea, vestibule, and semicircular canals in the temporal bone. The bony labyrinth contains perilymph and membranous sacs filled with endolymph. Within the membranous sacs of the vestibule and semicircular canals are equilibrium receptors. Hearing receptors are found within the membranes of the cochlea. The organ of Corti is receptor for hearing within the cochlea it is stimulated by sound vibrations transmitted through air, membranes, and fluids. Deafness is any degree of hearing loss. Conduction deafness results when the transmission of sound vibrations through the external and middle ears is hindered. Sensorineural deafness occurs when there is damage to the nervous system structures involved in hearing.

Lastly to talk about is the sense of smell and taste. The olfactory (smell) receptors are located in the superior aspect of each nasal cavity. Sniffing helps you to bring more air (containing odours) over the olfactory mucosa. Olfactory pathways are closely linked to the limbic system; odours recall memories and arouse emotional responses. Gustatory (taste) cells are located in the taste buds, primarily on the tongue. The four major taste sensations are sweet, salt, sour, bitter. Taste and appreciation of foods is influenced by the sense of smell and the temperature and texture of foods.

All throughout the reporting, the lesson was clearly discussed by the reporter and my professor. The reporter did a good job in preparing his visual aids. Our teacher gave us an activity in which we have to draw the anatomy of the eye which I enjoyed a lot because I’m somehow good in drawing .