DIAGRAM OF THE HUMAN NOSE

How does the human nose work?

How does the work?

The human nose works as a dual-function organ, serving as the primary entry point for respiration and housing the specialized structures for the sense of smell (olfaction).

🌬️ Respiration and Air Conditioning

The nose acts as an air filter and conditioner for the air we breathe before it reaches the lungs:

Filtering: Hairs in the nostrils trap large particles. The inner lining of the nasal cavity is covered in sticky mucus, which captures smaller particles like dust, pollen, and bacteria. Tiny hair-like projections called cilia sweep the contaminated mucus toward the throat to be swallowed.
Warming: Blood circulating close to the surface of the internal nasal structures rapidly warms the inhaled air to body temperature.
Humidifying: The moist mucous lining adds essential moisture to the air, preventing the lower respiratory tract from drying out.

👃 Olfaction (The Sense of Smell)

The actual process of smelling takes place in a small patch of tissue called the olfactory epithelium located high in the nasal cavity.

Detection: Airborne odor molecules enter the nose and dissolve in the mucus lining the olfactory epithelium.
Transduction: These molecules bind to olfactory receptor cells, which are specialized neurons. This binding converts the chemical signal into an electrical impulse.
Transmission: The impulses travel along the olfactory nerve (Cranial Nerve I) directly to the olfactory bulb in the brain.
Processing: From the olfactory bulb, signals are sent to the olfactory cortex for conscious identification of the smell, and importantly, directly to the limbic system (hippocampus and amygdala), which explains why smells are so powerfully linked to emotion and memory.

🎶 Voice Resonance

The nasal cavity and the connected air-filled spaces known as the paranasal sinuses also act as resonating chambers. The size and shape of these spaces influence the quality, tone, and volume of a person's voice.

Diagram of the Human Nose

How does the human nose work?Video

The Human Nose

The Human Nose: Anatomy and Function

The human nose is a complex organ that serves as the primary gateway for the respiratory system and houses the sense of smell. It is divided internally into two passages by the nasal septum.

Anatomy

External Structure: The visible part of the nose is supported by bone (the nasal bone) at the top and flexible cartilage at the bottom, which forms the nostrils (nares).
Nasal Cavity: This large, air-filled space behind the nose is lined with a specialized mucous membrane.
- Turbinates (Conchae): Three pairs of scroll-shaped bones (superior, middle, and inferior) project into the nasal cavity. These structures increase the surface area and create turbulence in the inhaled air.
Olfactory Epithelium: Located in the roof of the nasal cavity, this small patch of tissue contains olfactory receptor cells—the neurons responsible for detecting odors.
Paranasal Sinuses: These are air-filled, mucous-lined cavities within the facial bones (frontal, ethmoid, sphenoid, and maxillary) that connect to the nasal cavity.

Primary Functions

The nose performs three essential functions for the body:

1. Respiration (Filtering and Conditioning Air)

The nose acts as an air conditioner and filter for inhaled air before it reaches the sensitive lungs:

Warming: Blood circulating near the surface of the turbinates warms the incoming air to body temperature.
Humidifying: The mucous lining adds moisture to the air.
Filtering: Hairs in the nostrils (vibrissae) and sticky mucus trap dust, pollen, bacteria, and other foreign particles. Tiny hair-like projections called cilia then sweep the contaminated mucus towards the throat to be swallowed or expelled.

2. Olfaction (Sense of Smell)

The sense of smell, or olfaction, is the nose's unique sensory function:

Airborne odor molecules dissolve in the mucus of the olfactory epithelium.
They bind to the olfactory receptor cells, which fire electrical signals up the olfactory nerve (Cranial Nerve I).
The signals are transmitted directly to the olfactory bulb in the brain, and from there to the limbic system (explaining the strong link between smell, memory, and emotion) and the olfactory cortex for conscious interpretation.

3. Voice Resonance

The nasal cavity and the connected paranasal sinuses act as resonating chambers, affecting the unique sound quality and tone of a person's voice.

The external human nose, composed of bone and cartilage, is the most prominent feature of the face in humans. The internal human nose is a hollow structure above the roof of the mouth, divided by the septum into two nasal cavities that extend from the nostrils to the .

The mucous membrane that lines the nasal cavities is covered with fine hairs known as cilia that help to filter dust and impurities from the air before it reaches the lungs; the air is also moistened as it passes over the sticky nasal membrane. In the human nose, there are three horizontal folds on the walls of the nasal cavities, called the conchae: other mammals may have more conchae.

The uppermost concha is densely supplied with capillaries that warm the air passing over them to near body temperature. High in the nasal cavity is a small tract of mucous membrane containing the nerve cell endings of the olfactory nerve, which impart the sense of smell. Therefore, inflammation of the nasal mucous membranes, which commonly accompanies colds and other infections, not only obstructs breathing but also impairs the sense of smell.

Diagram of the human nose...

Diagram of The Human Nose

A diagram illustrating the human nose generally encompasses both its external and internal components. On the outside, it displays the nasal bridge, tip, nares (nostrils), alae (the sides of the nostrils), and columella (the tissue that divides the nostrils). Internally, the nasal cavity is partitioned by the septum and contains turbinates (conchae) and sinuses.

External Nose:

Nasal Bridge: The bony upper section of the nose.

Nasal Tip: The soft, rounded extremity of the nose.

Nares (Nostrils): The two apertures that permit air to enter the nasal passage.

Alae: The curved edges of the nostrils.

Columella: The tissue that divides the nostrils.

Internal Nose:

Nasal Cavity: The area within the nose, separated into two by the nasal septum.

Nasal Septum: A structure composed of bone and cartilage that divides the left and right portions of the nasal cavity.

Turbinates (Conchae): Bony projections lined with mucous membrane that assist in warming and humidifying the air.

Sinuses: Air-filled spaces within the skull that are connected to the nasal cavity.

Diagram of the Human Nose....anatomy-and-human-blockhead.

DIAGRAM OF THE HUMAN NOSE

DIAGRAM OF THE HUMAN NOSE...

The upper air passages pertain to the respiratory organs located in the human head. These include the nose and throat (pharynx).
When breathing in, air first enters through the nose, where it is initially filtered by a hair-like structure.
A bifurcated network of blood vessels within the nasal mucous membrane serves to warm the incoming air. Additionally, mucous droplets from the nasal mucous membrane help to moisten the air. This process prepares the air for the conditions found within the lungs (pulmo). The paranasal sinuses (sinus paranasales), which are connected to the nasal cavity, also play a role in this adaptation.
From the nose, the air travels to the throat, which comprises various sections, with the esophagus and windpipe intersecting in the medial throat (mesopharynx). The inhaled air continues through the throat to the larynx (larynx) and then to the lower air passages.
In contrast to the sense of taste, the sense of smell is capable of distinguishing a far greater variety of sensations. The qualitative categorization seen in taste (bitter, sweet, sour, salty) does not apply as straightforwardly to smell. Instead, scent classes are utilized to convey the experience (pungent, sweaty, rotten, etc.).
The sensory receptors of the olfactory organ (organum olfactus) are situated at the beginning of the respiratory tracts and are approximately the size of a dime, located on the upper nasal wall and the septum.
Due to pigmentation, the olfactory region appears yellow, which contrasts with the red membrane. It remains uncertain whether this pigmentation plays a role in the sense of smell. However, it is noted that animals lacking pigmentation (albinos) do not possess a sense of smell.
The tissue within the olfactory region, containing over 10 million receptor cells, is approximately 50 µm thicker than the epithelium of the respiratory tracts. The olfactory cells feature very fine hairs (cilia), with up to 12 per cell, and are coated in mucus. Nerve processes from the olfactory cells bundle together as fibers leading to the anterior section of the olfactory cortex at the base of the frontal brain. The olfactory cells are separated from the olfactory cortex by a very thin bone known as the sieve.. The olfactory cells are separated from the olfactory cortex by very thin bone, the sieve, through which the nerve fibers pass through small openings. After appropriate processing of the olfactory information, the smell becomes known.

Olfactory cells are chemical receptors, i.e. the stimulus of the olfactory cells is the result of a chemical process on the surface of the hairs. How the molecular reaction occurs, with which hundreds of different smells are distinguished, is unclear. Gaseous substances are easier to smell. A water-soluble property increases the ability to smell because the smell molecules enter the air through evaporation.

Diagram of the Human Nose....

diagram-of-human-nose

Structure of the Nose

Structure of the Nose

The external nose is visible and is pyramidal in shape, with the root located in the upper region and the base located in the lower region. The variance in shape depends on the shape of the ethmoid bone which is an anterior cranial bone located between the eyes. The internal nose is divided into the left and right nasal cavities by the nasal septum. The internal nose also consists of the skin-lined region known as the vestibule and the mucosa-lined region known as the nasal cavity proper.

The nasal framework

The nasal or piriform aperture is situated on the bony skull and represents a bony outline of the nasal cavity, which is the beginning of the respiratory tract. The nasal pyramid is located here with each side consisting of the frontal process of the maxilla and medial to the nasal bone which is linked to the frontal bone.

The nasal cartilage

The front of the nose consists of connective tissue with embedded small pieces of cartilage. This includes the nasal septum and the nasal tip cartilage (lesser alar cartilage and lateral greater alar cartilage). Whatever impression the nose makes as an aesthetically significant element of the face – high, broad, or even crooked – is largely determined by these small cartilages and the cartilaginous portions of the nasal septum. Frequently, the bony portion of the nose is affected by midfacial fractures (e.g., a nasal bone fracture).

A common cause of nasal fractures is blunt trauma. Manual alignment through the application of strong thumb pressure with anesthesia followed by repair may be necessary to prevent lasting misalignments. Injuries that lead to functional impairments may be corrected through nasal surgery or rhinoplasty.

Internal nose

The inner part of the nose is formed by the main nasal cavity which includes the nasal concha, nasal passages (nasal meatus), and paranasal sinus. The nasal septum comprises bone and cartilage in the nose and separates the nasal cavity into two fossae, which are continuations of the nostrils and jointly form their medial border. The nasal septum consists of four structures:

Clinically, deviations of the nasal septum occur quite frequently. These deviations may be present at birth or may result from an accident. A deviated nasal septum can lead to nasal congestion and breathing difficulties which may require surgical correction. Structure of the Nose .

Structure of the Nose Video :

UNDERSTANDING NASAL ANATOMY

UNDERSTANDING NASAL ANATOMY

A lot happens under the surface of the nose. The bone and cartilage under the skin give the nose most of its size and shape. Other structures inside and behind the nose help you breathe. Learning the anatomy of the nose can help you better understand how the nose works.

Bone.

This supports the bridge of the nose. The upper cartilage supports the side of the nose. The lower cartilage adds support, width, and height. It helps shape the nostrils and the tip of the nose.

Skin.

This also helps shape the nose.

Nasal cavity.

This is a hollow space behind the nose that air flows through.

Septum.

This is a thin wall made of cartilage and bone. It divides the inside of the nose into 2 parts.

Mucous membrane.

This is thin tissue that lines the nose, sinuses, and throat. It warms and moistens the air you breathe in. It also makes the sticky mucus that helps clean the air of dust and other small particles.

Turbinates.

These are curved, bony ridges on each side of the nose. They are lined with mucous membrane. They warm and moisten the air you breathe in.

Sinuses.

These are hollow, air-filled chambers in the bone around your nose. Mucus from the sinuses drains into the nasal cavity.

UNDERSTANDING NASAL ANATOMY VIDEO :

Physiology of the Human Nose

THE HUMAN NOSE

The human nose has several physiologic functions. As the air is inspired through the nose it is humidified and warmed by passing over the moist and warm nasal mucosa. The nose is an energy-conscious organ in that expired air is cooled and some of the moisture is recaptured. The functions of warming and humidification require a tremendous blood flow to the nasal mucosa and also place substantial stress on the nasal mucosa. The nose has what is known as a nasal cycle.

To allow the mucosa time to rest from these functions, the nose has periods in which one side of the nose becomes swollen, which we call congestion. During the same period the other side of the nose remains patent or decongested. The normal nasal cycle lasts from three to six hours, and during this time first one side of the human nose will be congested and the other side will be patent; then the second side becomes congested as the first side becomes patent. It is also normal for the human nose to be congested when an individual lies down.

Particularly if you lie on your side you may notice that the downside of your nose becomes congested. Olfaction is the medical word for smell. Smell is one of the six human senses and for some individuals is a very important sense; for others it seems to be less important. The olfactory centers, as described under the anatomy section, reside very high along the roof of the nose. In order for these centers to be stimulated, the odors have to be inspired into the human nose and carried up to the roof of the human nose. If the odor does not reach the roof of the nose due to a variety of conditions, the odor will not be perceived. The nose is capable of distinguishing a large number of different odors. Our understanding of precisely how this occurs is limited, but increasing.

Taste is a sense very different from olfaction. It is another of the human senses and is perceived primarily on the tongue. There are four recognized tastes and these are sweet, salty, sour, and bitter. They occupy geographically separate areas on the tongue and are perceived in cells clustered together in taste buds. The sense of smell plays a major role in the flavor of foods and it is common for individuals who lose their sense of smell to report that food loses its taste. This is of course incorrect; the food has only lost its aroma, and taste (sweet, salty, sour, bitter) remains intact.

Physiology of the Human Nose Video :\