Liver Definition

Do you know the secrets about the human liver anatomy? Let’s learn it here. Skin is the largest organ. Whereas, liver is the largest internal organ and the largest gland in the human body. You may wonder "What is liver?" and what a purpose it serves. Precisely, it is one of the most fantastic organs of your body.

Being a glandular structure, it is a group of cells or tissues that secrete or excrete certain substances. However, these secretions have to do their job elsewhere in the body. The largest gland, liver also enjoys the distinction of being the h
ottest organ in your body.


The answer to “What does the liver do?” contains some interesting information. The human liver is, actually, a gland. There is broad classification of glands into two major groups i.e. endocrine and exocrine glands. Interestingly, liver belongs to both of these categories.

That is, it serves as both an endocrine gland as well as an exocrine gland. A normal liver weighs about 1.2 to 1.5 kg and performs both endocrine and exocrine functions. Studying the human liver anatomy, you will also come to know about its size.

Keep on reading this article about the human liver anatomy. Here, you will get useful and interesting information about the liver size, location, function, diseases and risk factors for liver disease.

The human liver size varies across gender. That is, it is bigger in size in male as compared with the one in females. The size of this gland is around 10.5 centimeters for men and about 7 centimeters for women. In the similar way, the weight of this organ is also different in different genders.

The largest internal organ, liver appears in the right upper quadrant of the abdomen. It lies just beneath the right side of the diaphragm and under the right lower rib cage. Concerning human liver anatomy, there are eight functional segments in it.

Within a minute, approximately 1500 ml of blood flows through the liver. This is so to ensure its efficient working. Partly due to its ample blood supply, liver is the prime site for metastatic spread of cancer.

Eye Definition

What do you know about the eye definition biology? Just learn about human eye facts and you will get precious information about it. You can define the eye as an organ of vision which makes you visualize the world around you. The eyes are two in number and each is placed inside specialized compartments in the skull.

The human eye is the organ which enables you to see. The human eye does not only let you view the scenes and phenomenon in your surroundings, but also enables you to differentiate between colors. Sometimes, there is a minor defect in the eye function and the individual cannot make difference between the red and green color. What is the name for such a condition? Well, you call it ‘color blindness

Eye function renders you the sense of sight. They convert light into electrical signals. Afterwards, the brain deciphers these electrical signals into images. Properly working healthy eyes are able to perform the following functions.

It is one of the important human eye facts that they help us view our surroundings.

Our eyes enable us to see colors. Certain organisms, such as dogs, cannot see colors and, so, their world is black and white.

Eyes help us see near as well as distant objects.

When we see an object, light is reflected off it into our eyes.

The light rays entering our eyes first pass through the pupil. These are the muscles of iris that control the size of the pupil.

After passing through the pupil, light passes through the transparent lens of the eye. There occurs the refraction and focusing of the light rays on the retina.

Light sensitive cells, rods and cones, present in the retina covert the light rays into electrical impulses. Isn’t it one of the most amazing facts about eyes of human beings.

The optic nerve transfers these electrical impulses from the retina to the brain which then processes these signals and translates them in the form of an image.

Thyroid

   

 Thyroid gland is the largest endocrine gland in adult human. Endocrine glands are those that secrete their products directly into the bloodstream. In contrast, most exocrine glands release their secretions through a duct onto an epithelial surface such as skin or mucosa. Thyroid gland is made up of two lateral lobes joined together across midline by a narrow bridge of tissue called isthmus. It is relatively larger in women and children than in men.

Thyroid gland lies in the anterior part of our neck, immediately below the larynx and overlying the trachea (windpipe). A normal thyroid gland weighs between 25 and 40 gm. This butterfly shaped gland is highly vascular so it receives one of the highest rates of blood flow per gram of tissue. Thyroid gland moves with the larynx in swallowing and speaking - this feature helps a healthcare professional to differentiate swellings in the glands from those in the adjacent structures.

Thyroid gland lies in the anterior part of our neck, immediately below the larynx and overlying the trachea (windpipe). A normal thyroid gland weighs between 25 and 40 gm. This butterfly shaped gland is highly vascular so it receives one of the highest rates of blood flow per gram of tissue. Thyroid gland moves with the larynx in swallowing and speaking - this feature helps a healthcare professional to differentiate swellings in the glands from those in the adjacent structures.


Iodine is essential for thyroid hormone synthesis. Dietary intake of about 150 microgram per day mainly in the form of iodide is typical to maintain normal thyroid hormone secretion. In many countries common table salt is iodized to prevent iodine deficiency. Iodine deficiency is the most common cause of goiter which is considered as one of the thyroid diseases.

⇛ Thyroid hormones are essential for normal growth and maturation. They play crucial role in the development of central nervous system (CNS). The most serious effect of thyroid hormone deficiency during childhood is permanent brain damage and dwarfism.

⇛ Thyroid hormones accelerate cholesterol clearance from the plasma.

⇛ Thyroid hormones are required for conversion of carotene to vitamin A; patients with hypothyroidism may suffer from night blindness.

⇛ Thyroid gland also releases a minor hormone called calcitonin which is involved in calcium and phosphate metabolism. Calcitonin stimulates cartilage growth and causes increased deposition of calcium in the bones therefore promoting bone formation and reducing calcium concentration from the blood.

Spleen

Spleen is the largest lymphatic organ in the human body. Lymphatic or lymphoid organs are the major parts of the immune system of our body. Function of the immune system is to protect the host from the invasion of foreign organisms. Immune system helps the body to distinguish its own tissues from external substances such as bacteria, viruses and toxins. Thus dysfunction or deficiency of components of the immune system can lead to various diseases ranging from arthritis, HIV and cancer.

                               

Spleen weighs about 150 gm in adults and lies under the diaphragm in the left upper part of the abdomen at the level between 9th and 11th ribs. Anterior to the spleen lies stomach and medially lies the superior part of the left kidney. Spleen resembles the size and shape of a clenched fist.

⇛ Spleen participates in the primary immune response to invading bacteria, viruses, parasites or foreign particles. Spleen is a strong defense against blood-borne pathogens. Removal of spleen increases the risk of infection.

⇛ Spleen acts like a filter for the blood; it removes cellular residues, particulate matter, senescent RBCs and other abnormal cells from the bloodstream.

It is the abnormal enlargement of spleen. When the spleen is diseased it can be 10 times larger than its normal size. Causes include:

⇛ parasitic infection such as malaria, kala azar
⇛ chronic tuberculosis
⇛ typhoid, septic shock, infective endocarditis
⇛ rheumatoid arthritis, systemic lupus erythematosus
⇛ portal hypertension, liver diseases
⇛ lymphomas, anemia, leukemia

Pituitary Gland

Hormones are chemical mediators that control and regulate the entire mechanism of the body throughout an individual's lifespan. These hormones are secreted by specific ductless glands spread across various organs of the body. The pituitary gland or hypophysis regulates the hormonal secretions and controls the growth,

development, secretions and functioning of other endocrine glands, for example, adrenal glands. This small endocrine gland has got a pea-sized body and is found at the base of brain in the skull cavity lying below the controlling organ, called hypothalamus. Owing to its large impact on the body, pituitary is also known as the “master gland”.

⇏ Measuring about the size of a pea, this pink-colored hormone secreting organ measures 5 grams in weight, and is located in the folds of brain.

⇏ The height, shape and size of an individual is greatly influenced by the activity of pituitary gland. The excessive secretion of growth hormone leads to increased height and its decreased secretion results in dwarfism.

⇏ Pituitary gland is called the king of all glands (or master gland) as it controls them all and is in-turn controlled by the Hypothalamus.

⇏ It is pituitary that serves as the center of sexuality and reproduction in your body. In other words, the secretions of the posterior lobe of the pituitary are responsible for child birth and sexual life of an individual.

⇏ Though many other parts of the body are actively involved in sexual processes, this gland enjoys a prominent position because it initiates all such processes.

⇏ Do you know around 30 to 40% percent of population suffers from sexual dysfunction at some time in life? It is because of the malfunctioning of the pituitary gland.

⇏ A connection is built between endocrine and nervous systems through hypophysis (an alternative term to denote hypothalamus).

⇏ The gland hangs from a part of the brain called the hypothalamus and is connected with the same through a small stalk called the infundibulum.

⇏ The hypophysis generates and releases nine hormones, in total, into the blood stream which mainly serve to maintain homeostasis in the body.

⇏ Having its origin in the pituitary gland, the Cushing’s disease is a deadly condition that is very difficult to diagnose and treat.

⇏ Cortisol or ACTH is a life hormone that is regulated by the pituitary. We would soon die in the absence of this hormone!

Mouth Definition

A precise answer to what is mouth is that it is the anterior most part of the gastrointestinal tract. According to mouth definition, this organ is also known as the oral cavity. This cavity contains several different other organs. Organs in the oral cavity include uvula, palate, teeth, tongue, and so on.

In the pictures about what is mouth, you can distinguish the palate into soft palate and hard palate. Each type has got its own role to play in the mouth. On the other hand, different structures of the human mouth perform a number of important functions. They include sound production, breathing, tasting, and grinding and masticating food, etc. Below is further detail about what is mouth.

 Secretion of saliva is also a mouth function. Meanwhile, there are several articulatory and static organs in the oral chamber. They significantly contribute to the production and modification of sounds. Initially, the sounds start from the vibration of vocal cords in the laryngeal cavity.

Another name for the laryngeal cavity is the voice box. A number of mild and critical mouth diseases have been affecting one of the most important organs of your body. Some of these conditions do not even require formal treatment.

In other words, you can easily cure them by proper modifications in the behavior. However, other diseases need urgent, prolonged and very expensive treatment measures. Such measures include medications and surgical therapy.

Study of mouth parts is pertinent to the topic what is mouth. Moving in sequence from anterior to the posterior, you will come across different mouth parts. These are: lips, teeth, tongue, alveolar ridge, soft and hard palate, uvula and throat. The teeth ridge or gum ridge are alternative names for the alveolar ridge.

However, if you look at the human mouth externally, many structures of the front part of head may be included in it. They collectively form the facial organs, namely, lips, nose, chin, cheeks, eyes, eyebrows and forehead.

Lips are the soft, movable and flexible muscular structures. They are under the voluntary control of an individual. Therefore, you can open, close, or round them at will. In digestive system, their function is to serves as a passage for dietary and fluid intake.

Larynx Definition

Larynx Definition

What is larynx? Talking about the larynx definition, it is structure lying just at the top of trachea. It plays a significant role in the production of vocal sounds. The larynx is also responsible for the protection of windpipe against the entry of food particles.

Owing to its great contribution to phonation, it is also known as voice box or sound apparatus. The voice box contains vocal cords.

In human adults, it lies at the level of third to sixth vertebrae of the cervical region. But in newborn babies, it is at a higher position. That is, here you will find it at the point of second to third vertebrae. As you can see in the larynx pictures,

Larynx covers the tracheal opening through a flexible flap, i.e. epiglottis. The epiglottis sits on the aperture like a lid. To learn more about larynx definition and function, just go through the rest of the article.

Parts of Larynx

After learning the larynx definition, you need to proceed to its parts. The larynx cartilage makes up the structure of the sound apparatus. There are nine laryngeal cartilages in the skeleton of this body part. Out of nine cartilages, six appear in the form of pairs. While the other three remain single. The unpaired cartilages are cricoids, thyroid and epiglottis.

On the other hand, the cuneiform, corniculate and arytenoids are three paired ones. However, talking of the interior of sound apparatus, you can distinguish it into three divisions, viz. subglottis, glottis and supraglottis.

Meanwhile, there are also a number of intrinsic and extrinsic muscles that are present in the region. These muscular structures facilitate the functioning of the organ in various ways. For example, the intrinsic cricothyroid muscles help in the stretching and elongation of the vocal folds.

Different types of sensory and motor nerves innervate various muscular structures of larynx. They include vagus, superior laryngeal and recurrent laryngeal nerves. The vocal folds of voice box are of two types, i.e. false and true.

Here the former do not contain muscle and have nothing to do with the production of sound. But they play their role in the resonance. The true mucosal folds, on the other hand, do have skeletal muscle and play an active role in phonation.