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.

OTHER SOURCES

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

Anatomy, Function, and Importance

The human nose is much more than a facial feature—it is a highly specialized organ central to respiration, olfaction (sense of smell), immune defense, and speech resonance. Its complex structure and physiological roles make it essential for overall health and well-being.

This guide explores the anatomy, functions, and clinical significance of the human nose.

External Structure

The external nose includes:

Nasal bones: Form the upper bridge.
Cartilages: Lateral, alar, and septal cartilages shape the tip and nostrils.
Nostrils (nares): Two openings allowing airflow into the nasal cavity.

Key roles:

Directs air efficiently into the respiratory tract.
Provides structural support to the face.
Contributes to air resistance for proper breathing.

Internal Structure: The Nasal Cavity

The internal nose consists of the nasal cavity, separated by the nasal septum into left and right chambers.

Key Features:

Nasal Septum: Made of bone and cartilage, divides the cavity and maintains structural integrity.
Mucous Membrane: Lines the cavity; produces mucus to trap dust, pathogens, and allergens.
Cilia: Tiny hair-like structures move mucus toward the throat for clearance.
Vestibule: Entry zone lined with vibrissae (nose hairs) for coarse filtration.

Nasal Conchae (Turbinates)

Three curved bony structures on the lateral walls:

Functions:

Increase surface area for air warming and humidification.
Create turbulence to improve filtration and olfaction.
Regulate airflow through the nasal passages.

Olfactory Region

Located in the upper nasal cavity, this region contains olfactory epithelium:

Olfactory receptor neurons detect odor molecules.
Supporting cells maintain structure.
Basal stem cells regenerate olfactory neurons.

Function: Allows humans to perceive smells and connect odors with memory and emotion.

Paranasal Sinuses

Four paired air-filled cavities:

Roles:

Reduce skull weight
Produce mucus for pathogen trapping
Enhance resonance for speech

Blood Supply and Nerve Connections

Blood supply: Branches from sphenopalatine, facial, and ophthalmic arteries.
Innervation: Trigeminal nerve for sensation; olfactory nerve for smell.

Rich vascularization warms inhaled air and plays a role in nosebleeds (epistaxis).

Functions of the Human Nose

Air Filtration: Traps dust, pollen, and microbes.
Air Conditioning: Warms and humidifies inhaled air.
Olfaction: Detects smells via the olfactory region.
Immune Defense: Mucus and cilia trap and remove pathogens.
Speech Resonance: Nasal cavity acts as a sound chamber.

Clinical Significance

Common conditions affecting the nose include:

Deviated septum: Can disrupt airflow and cause snoring or sleep apnea.
Nasal polyps: Obstruct airflow and sinus drainage.
Chronic sinusitis: Inflammation of sinuses causing congestion and pain.
Anosmia: Loss of smell due to damage or infection affecting the olfactory region.

Understanding nasal anatomy is critical for ENT specialists, respiratory therapists, and general healthcare professionals.

Conclusion

The human nose is a multifunctional organ that plays vital roles in breathing, smell, immunity, and communication. Its intricate anatomy and physiology demonstrate the remarkable design of the human body. Maintaining nasal health through proper hygiene, hydration, and medical care is essential for overall well-being.

SEO Keywords

Human nose anatomy, nasal cavity, nasal physiology, olfactory system, nasal turbinates, paranasal sinuses, nose function, respiratory health

OTHER SOUCES

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 ().

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 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 ().

The paranasal sinuses (), 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) 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, 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 .
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 (), 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 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....VIDEO

Structure of the Nose

Structure of the Nose

Anatomy, Functions, and Clinical Significance

The human nose is a remarkably complex organ that serves as the primary passage for air, a sensory organ for smell, and an important part of the immune defense system. Its structure is carefully designed to support breathing, olfaction, and speech. Understanding the nose’s anatomy is essential for anyone interested in health, medicine, or physiology.

External Nose: The Visible Framework

The external nose is the part of the nose you see on the face. It consists of:

Nasal bones: Form the upper bridge of the nose.
Cartilaginous structures: Include lateral, septal, and alar cartilages that shape the tip and nostrils.
Nostrils (nares): Two openings that allow air entry.

Function:
The external nose guides airflow into the nasal cavity, supports facial structure, and provides an aesthetic appearance. Its shape also influences air resistance, which is important for effective respiration.

Internal Nose: The Nasal Cavity

The nasal cavity extends from the nostrils to the nasopharynx and is separated by the nasal septum into two symmetrical chambers.

Key Components:

Nasal Septum:
- Composed of bone (vomer and perpendicular plate of the ethmoid) and cartilage.
- Divides the nasal cavity and supports airflow regulation.
Mucous Membrane:
- Lines the nasal cavity.
- Contains cilia to move mucus and trapped particles toward the throat.
- Produces mucus to trap dust, allergens, and pathogens.
Vestibule:
- The front portion of the nasal cavity.
- Lined with hair (vibrissae) that filters large particles.

Nasal Conchae (Turbinates)

The turbinates are curved bony structures on the lateral walls of the nasal cavity:

Inferior turbinate
Middle turbinate
Superior turbinate

Functions:

Increase surface area for air contact.
Create turbulence to warm, humidify, and filter air.
Enhance the effectiveness of the olfactory region.

Olfactory Region

Located in the upper part of the nasal cavity, this area contains olfactory epithelium with:

Olfactory receptor neurons: Detect smell.
Supporting cells: Maintain structure and function.
Basal cells: Regenerate olfactory neurons.

Function:
The olfactory region allows humans to detect and distinguish odors, linking smell to memory and emotion through the olfactory nerve.

Paranasal Sinuses

The paranasal sinuses are air-filled cavities surrounding the nasal cavity:

Frontal sinuses
Maxillary sinuses
Ethmoid sinuses
Sphenoid sinuses

Functions:

Reduce skull weight
Produce mucus for trapping pathogens
Act as resonating chambers for speech

Blood Supply and Innervation

Blood supply: From branches of the sphenopalatine, facial, and ophthalmic arteries.
Nerves: Trigeminal nerve for sensation; olfactory nerve for smell.
The rich vascular network helps warm inhaled air and can contribute to nosebleeds (epistaxis).

Functional Significance of Nasal Structure

The nose’s structure enables multiple essential functions:

Air filtration: Traps dust, pollen, and pathogens.
Air conditioning: Warms and humidifies inhaled air.
Olfaction: Smell detection via olfactory region.
Resonance in speech: Nasal cavity acts as a sound chamber.
Immune defense: Mucosa and cilia remove harmful particles.

Clinical Relevance

Understanding nasal anatomy is critical for diagnosing and treating:

Deviated septum – may affect airflow and breathing.
Nasal polyps – obstruct normal nasal function.
Chronic sinusitis – inflammation of sinuses affecting airflow.
Anosmia – loss of smell due to olfactory region damage.

Conclusion

The structure of the nose is a masterclass in biological engineering. Its external and internal frameworks, combined with specialized regions like turbinates and olfactory epithelium, allow it to perform vital functions ranging from respiration and smell to immunity and speech resonance. Maintaining nasal health is crucial for overall respiratory efficiency and sensory well-being.

OTHER SOURCES

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

The Gateway to Respiratory and Olfactory Health

The human nose is more than a facial feature—it is a complex organ integral to respiration, smell, immunity, and speech. Its intricate anatomy allows the body to filter, warm, and humidify inhaled air while protecting the lungs from pathogens and irritants. Understanding nasal anatomy is key to appreciating how this remarkable organ supports overall health.

This comprehensive guide explores the structure of the nose, its functional regions, and clinical relevance.

External Nose: The Visible Gateway

The external nose forms the most recognizable part of the face and serves as the primary entrance for air.

Key Features:

Nasal bones: Form the upper bridge.
Cartilage: Shapes the tip and nostrils.
Nostrils (nares): Two openings allowing air entry.

Functionality:

Directs airflow efficiently into the nasal cavity.
Provides resistance to optimize breathing.
Supports the face structurally and aesthetically.

Internal Nasal Anatomy

The internal nose, or nasal cavity, extends from the nostrils to the nasopharynx and is divided by the nasal septum into two chambers.

1. Nasal Septum

Made of bone and cartilage.
Separates the two nostrils.
Provides structural stability and regulates airflow.

2. Nasal Cavity Lining

Covered with mucous membrane.
Houses cilia, which move mucus and trapped particles toward the throat.
Produces mucus to trap dust, bacteria, and allergens.

Nasal Conchae (Turbinates): The Air Conditioners

Three bony structures on each side of the nasal cavity:

Physiological roles:

Increase surface area for air contact.
Create turbulence to warm, humidify, and filter air.
Improve olfactory exposure for smell detection.

Olfactory Region: The Sense of Smell

Located in the upper nasal cavity, this region contains olfactory epithelium, consisting of:

Olfactory receptor neurons
Supporting cells
Basal stem cells

Function:

Detects odor molecules dissolved in mucus.
Sends signals to the brain via the olfactory nerve.
Connects smell with memory and emotion, demonstrating the nose’s neurophysiological importance.

Nasal Sinuses: Lightweight and Resonant Structures

The paranasal sinuses—frontal, maxillary, ethmoid, and sphenoid—are air-filled cavities surrounding the nasal cavity.

Roles in nasal anatomy:

Reduce skull weight.
Produce mucus to trap pathogens.
Serve as resonating chambers for speech.

Blood Supply and Nervous Connections

Blood supply: Primarily from the sphenopalatine, facial, and ophthalmic arteries.
Innervation: Trigeminal nerve provides sensation; olfactory nerve transmits smell.
Rich vascularization contributes to air warming and plays a role in nosebleeds (epistaxis).

Nasal Physiology and Clinical Relevance

Understanding nasal anatomy explains common conditions:

Deviated septum: Alters airflow, may cause snoring or sleep apnea.
Nasal polyps: Obstruct airflow and sinus drainage.
Rhinitis and sinusitis: Result from inflammation of mucosa.
Anosmia (loss of smell): Often related to olfactory region damage or infection.

Proper nasal function ensures efficient breathing, optimal oxygen uptake, and immune defense.

The Nasal Cycle: An Anatomical Curiosity

The nasal cycle is a physiological alternation in congestion and decongestion between nostrils every few hours.
Purpose:

Allows mucosa recovery.
Maintains airway efficiency.

This subtle anatomical feature is normal and supports overall nasal health.

Conclusion

Understanding nasal anatomy is fundamental for appreciating how this small but complex organ impacts respiratory health, sensory perception, and overall well-being. From filtering and conditioning air to detecting odors and supporting speech, the nose is a marvel of anatomical design.

Maintaining nasal health through hygiene, proper hydration, and prompt treatment of infections helps preserve its critical physiological functions.

OTHER SOURCES

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

Structure, Function, and Clinical Significance

The human nose is far more than a simple airway for breathing. It is a complex, highly specialized organ responsible for respiration, olfaction (smell), immune defense, and speech resonance. Its intricate physiology allows the body to filter, warm, humidify, and analyze the air we breathe—while simultaneously protecting the lower respiratory tract from pathogens and irritants.

This article explores the anatomy and physiology of the human nose, how it functions in health, and why it is vital to overall respiratory and neurological well-being.

Overview: What Is the Human Nose?

Physiologically, the nose is the primary entrance to the respiratory system and the sensory organ for smell. It works continuously to:

Regulate airflow
Condition inhaled air
Detect odors
Provide immune defense
Assist speech resonance

The nose is divided into external and internal components, each contributing to its overall function.

Anatomy of the Human Nose (Physiological Perspective)

1. External Nose

The external nose includes:

Physiological role:

Directs airflow
Provides structural support
Influences airflow resistance and turbulence

2. Nasal Cavity

The nasal cavity is divided into two chambers by the nasal septum and lined with specialized mucous membranes.

Key features:

Vestibule – initial air entry
Respiratory region – air conditioning
Olfactory region – smell detection

3. Nasal Turbinates (Conchae)

Three bony structures on each side:

Physiological functions:

Increase surface area
Create airflow turbulence
Enhance warming and humidification
Improve odor detection

Physiology of Nasal Breathing

1. Air Filtration

As air enters the nose:

Vibrissae (nose hairs) trap large particles
Mucus captures dust, bacteria, and allergens
Cilia move contaminants toward the throat for swallowing or expulsion

This process is part of the mucociliary clearance system, a key innate immune defense.

2. Air Warming and Humidification

The nasal lining is rich in blood vessels.

Physiological effects:

Warms cold air to near body temperature
Adds moisture to prevent airway dehydration
Protects lung tissue from irritation

Up to 90% of air conditioning occurs in the nose before air reaches the lungs.

3. Regulation of Airflow Resistance

The nose naturally regulates airflow through:

Nasal valve area
Turbinate swelling and decongestion cycles

This ensures optimal oxygen uptake and balanced airflow between nostrils.

Olfactory Physiology: How the Nose Enables Smell

Olfactory Epithelium

Located in the upper nasal cavity, it contains:

Olfactory receptor neurons
Supporting cells
Basal stem cells

Odor molecules dissolve in mucus and bind to receptors, triggering nerve impulses.

Signal Transmission

Odorant binds receptor
Electrical signal generated
Signal travels via olfactory nerve
Processed in olfactory bulb
Sent to brain regions for memory and emotion

This explains why smell is strongly linked to memory and emotion.

Immune and Protective Functions of the Nose

The nose is a frontline immune organ.

Defense Mechanisms Include:

Antimicrobial enzymes (lysozyme, defensins)
Immunoglobulin A (IgA)
Resident immune cells
Mucus barrier

These mechanisms help prevent infections such as:

Nasal Cycle: A Unique Physiological Phenomenon

The nasal cycle is an alternating congestion and decongestion of nostrils every 2–6 hours.

Purpose:

Allows tissue recovery
Maintains mucosal health
Optimizes air conditioning

This process is normal and usually unnoticed.

Role of the Nose in Speech and Resonance

The nose contributes to vocal quality by:

Acting as a resonating chamber
Modulating airflow during speech
Enabling nasal sounds (m, n, ng)

Blocked nasal airflow alters voice tone, resulting in hyponasal speech.

Clinical Relevance of Nasal Physiology

Disruption of nasal physiology can lead to:

Understanding nasal physiology is critical for:

ENT diagnosis
Respiratory health
Surgical planning
Allergy management

The Nose and Whole-Body Health

Proper nasal function supports:

Lung efficiency
Brain oxygenation
Immune health
Sleep quality
Exercise performance

Mouth breathing bypasses these benefits and may negatively affect long-term health.

Conclusion

The physiology of the human nose reflects a remarkable balance of structure, function, and defense. Far beyond its role in breathing, the nose is a dynamic organ that conditions air, protects the body, enables smell, and contributes to communication and neurological processing.

Maintaining healthy nasal function is essential for optimal respiratory performance and overall well-being.

OTHER SOURCES

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 :\