Where is nasal cavity

Diagram of the paranasal sinuses. Types of cells in the nasal cavity and paranasal sinuses. The mucous membrane has many types of cells, including: squamous cells, which make up most of the mucous membrane gland cells, which make mucus and other fluids nerve cells, which are responsible for the sense of smell in the nose immune cells, which help fight infection.

Other nearby structures. Other structures near the nasal cavity and paranasal sinuses include: lymph nodes in the neck called cervical lymph nodes nerves, which control swallowing, vision, smell, hearing and eye movement bones of the skull, such as the bones that make up the eye socket called the orbit , sphenoid bone, ethmoid bone and maxilla.

What the nasal cavity and paranasal sinuses do. The main functions of the nasal cavity and paranasal sinuses are to: filter, warm and moisten the air you breathe give you a sense of smell make mucus lighten the weight of the skull vibrate resonate , which helps to give your voice a unique sound protect the brain from injury.

Human Anatomy. San Francisco: Pearson Benjamin Cummings; Cancer of the head and neck. Cancer: Principles and Practice of Oncology. Runbin P, Hansen JT. Tabaee A, Persky MS. Cancer of the nasal vestibule, nasal cavity, paranasal sinuses, anterior skull base, and orbit: Surgical management. Wheaters's Functional Histology.

Churchill Livingston; The nasal mucosa , also called respiratory mucosa, lines the entire nasal cavity, from the nostrils the external openings of the respiratory system to the pharynx the uppermost section of the throat. The external skin of the nose connects to the nasal mucosa in the nasal vestibule. A dynamic layer of mucus overlies the nasal epithelium the outermost layer of cells of the nasal mucosa.

The initial one-third of the nasal cavity is lined by stratified squamous epithelium smooth epithelium consisting of flat surfaced cells , several cell layers thick. The outmost layer of squamous cells overlies a layer of proliferative cells cell which divide and replicate to form new cells which is attached to a basement membrane, a network of tough fibres which supports the epithelium.

The posterior two-thirds of the cavity is lined with pseudostratified columnar ciliated epithelium a type of epithelium in which cells arrange themselves in columns and project tiny hairs called cilia containing goblet cells mucus producing cells , and which overlies a basement membrane.

The nasal sub-mucosa underlies the basement membrane. This layer is made up of glands which secrete watery substances and mucus, nerves, an extensive network of blood vessels and cellular elements like blood plasma. The entire mucosa is highly concentrated with blood vessels and contains large venous-like spaces; bodies which have a vein-like appearance and swell and congest in response to allergy or infection. Mucosa of the olfactory system Unlike other nasal mucosa, the epithelium of the olfactory system does not project cilia.

This mucosa contains nerves which connect to the olfactory nerve. The nasal cavity functions to allow air to enter the respiratory system upon respiration.

Structures within the cavity regulate the flow of air and particles it contains. The olfactory region of the nasal cavity regulates the sense of smell. Conchae turbinate bones The conchae turbinate bones of the nasal mucosa expand the total surface area of the mucosa and create turbulence in air entering the respiratory passage.

This causes air to swirl as it moves through the nasal cavity and increases contact between infiltrating air and the nasal mucosa, allowing particles in the air to be trapped before entering other parts of the respiratory system e. Olfactory system The olfactory system functions to process sensory information related to smell. They also secrete the pigment which gives this mucus its yellow colour. Mucus secreted by these glands dissolves odours as they enter the nose, enabling them to interact with the olfactory receptors.

Paranasal sinuses The paranasal sinuses function to resonate speech and produce mucus which enters the nasal passage. Other functions of the sinuses are not well understood. Nasolacrimal ducts The nasolacrimal ducts drain tears from the lacrimal tear ducts of the eyes, to the nasal mucosa.

The nasal mucosa plays an important role in mediating immune responses to allergens and infectious particles which enter the nose.

It helps prevent allergens and infections from invading the nasal cavity and spreading to other body structures, for example the lungs. The mucus secreted by and which lines the mucosa provides a physical barrier against invasion by pathogens harmful microorganisms. It is sticky and traps pathogens when they enter the nasal cavity. Trapping pathogens enables components of the mucus to attack and destroy the microbes. For example, an antibody called IgA prevents pathogenic microbes from attaching to cells of the mucosa and in doing so prevents them from invading the cells.

Lysozyme enzymes which breakdown bacteria is another component of the nasal mucus. It works to degrade pathogenic microbes. The epithelial or outer cells of the nasal mucosa are constantly being worn away and replaced by new cells from the underlying proliferative regenerative layer.

This provides additional protection as it ensures that pathogens which do manage to invade the outer cell layer are removed as the epithelial cells are sloughed off. However, in some individuals abnormal responses of the nasal mucosa occur and immune responses are mounted against allergens which the body does not usually recognise as pathogenic and thus does not usually mount an immune response to.

In these individuals the mucosa, which usually functions to protect the body from invading microorganisms, is also thought to play a role in the pathological allergic response referred to as a type 1 hypersensitivity reaction.

This type of allergic response is mediated by B cells antibody producing cells of the immune system , which begin producing immunoglobulin type E IgE discussed further below. Epithelial cells Epithelial cells form the epithelium or surface layer of the nasal mucosa. Historically nasal mucosa epithelial cells were thought to simply:. However, recent evidence suggests the functions of epithelial cells are much broader and that they also regulate immune responses which occur if the physical barrier fails and pathogens infiltrate cells of the nasal mucosa.

The epithelium contains antigen-binding proteins protein chain sections of an antibody that recognise and join to antigens. These proteins are involved in the processes through which allergens are presented to antigen presenting cells. These cells are responsible for introducing pathogens to the T-lymphocyte cells T cells which in turn function to mount an immune response to destroy allergens presented to them.

That is; T cells that have not previously encountered, and therefore do not yet recognise as pathogenic, the specific antigen being presented. Thus, antigen-binding proteins in the epithelium catalyse the series of processes through which T cells begin to recognise and respond to allergens.

Epithelial cells also release factors which enhance inflammatory responses. The most important of these factors are cytokines proteins which regulate the duration and intensity of immune responses. Allergens can directly activate the epithelial cells to produce an inflammatory response, or the epithelial cells may mount such a response in response to T cell recognition of the antigen. Epithelial cells also appear be involved in the IgE-producing processes which perpetuate allergic responses discussed further below.

Endothelial cells Endothelial cells are cells which line the walls of the arteries that feed the nasal mucosa. They are also involved in allergic responses. They primarily function to attract leukocytes white blood cells circulating in the blood to the site of inflammation. Mucus glands Glands in the nasal mucosa produce a sticky mucus which moistens air and traps bacteria as they enter the respiratory passage.

Cilia Cilia or small hairs which project from the epithelium and line the nasal mucosa create motions which drain mucus from the nasal passage to the throat from where it is swallowed and digested by stomach juices. The activity level of cilia is dependent on temperature and in cold temperatures cilia become less active. Mucus may accumulate in and drip from the nostrils runny nose in these conditions. Infectious particles and allergens also impair cilia activity and can lead to symptoms such as a congested or runny nose.

Underlying blood vessels The thin walled veins on which the nasal mucosa rests function to warm air entering the respiratory passage.

Due to the high concentration of blood vessels in the nasal cavity, changes in these blood vessels contribute to nasal congestion. For example, constriction of these blood vessels decreases airway resistance, making it easier for air to enter the respiratory system.

The nasal nerves also regulate the congestion response. Nerves Innervation of the nasal mucosa is regulated by the trigeminal and maxillary nerves which also provide sensations to other areas of the face. The trigeminal nerve regulates sensations including touch, pressure and temperature in the nose, while sympathetic and parasympathetic innervation innervation which controls involuntary movements like constriction and dilation of the blood vessels occurs via the maxillary nerve.

The different types of nerves found in the nasal cavity and mucosa have various functions. For example, constriction of blood vessels which feed the nasal cavity is regulated in part by the sympathetic nervous system, while the parasympathetic nervous system plays a role in regulating secretions of mucus from nasal glands. Other nerves in the nasal cavity influence the dilation of blood vessels, nasal secretions, inflammation and interactions between nerves and the mast cells which mediate allergic responses.

Venous-like spaces Venous-like spaces found throughout the nasal mucosa swell and become congested in response to allergens and infection. Milestones in Cancer Research and Discovery. Biomedical Citizen Science. Director's Message.

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