1.1 Describe the structure and functions of the mouth

This guide will help you answer 1.1 Describe the structure and functions of the mouth.

The mouth is a key component of the human body’s digestive and respiratory systems. It plays an essential role in speech, eating, and protecting the body from harmful invaders like bacteria and viruses. This guide covers the structure and functions of the mouth.

The Structure of the Mouth

The mouth is composed of several structures that work together to perform its functions. The following explains each in turn:

Lips

The lips form the soft, outer boundary of the mouth. They are made of skin and muscle. The lips help manipulate food during eating and are essential for speech sounds, such as “p” and “b”. They also protect the mouth from external debris.

Oral Cavity

The oral cavity is the space inside the mouth. It is divided into the vestibule (the area between the teeth and the lips/cheeks) and the oral cavity proper (behind the teeth). It is lined with a mucus membrane, which keeps the mouth moist and provides some protection from infection.

Teeth

An adult usually has 32 teeth, divided into four types:

• Incisors: Sharp teeth at the front for cutting food.
• Canines: Pointed teeth next to the incisors for tearing food.
• Premolars: Flattened teeth located behind the canines for crushing and grinding food.
• Molars: Larger, even flatter teeth at the back of the mouth for more efficient grinding.

Each tooth has three main parts:

• Enamel: The hard, outer protective layer.
• Dentin: A softer layer beneath the enamel.
• Pulp: The innermost part, containing blood vessels and nerves.

Tongue

The tongue is a muscular organ. It is covered with tiny bumps called papillae, which house taste buds. The tongue’s main roles are to move food around during chewing, help form speech sounds, and detect tastes. Its mobility and sensory abilities make it highly versatile.

Hard and Soft Palate

The palate forms the roof of the mouth. The hard palate is the front section, made of bone. It provides a rigid surface for the tongue to press against when chewing. The soft palate is at the back and consists of soft tissue. It closes off the nasal passages when swallowing, preventing food or liquid from entering the nose.

Uvula

The uvula is the small, fleshy projection hanging at the back of the soft palate. It helps with speech sounds and triggers the gag reflex, a protective mechanism to stop foreign objects from entering the throat.

Salivary Glands

The salivary glands produce saliva, which enters the mouth through small ducts. Humans have three main pairs of salivary glands:

• Parotid glands: Located near the ears.
• Submandibular glands: Found under the jaw.
• Sublingual glands: Located beneath the tongue.

Saliva contains enzymes that start digesting food. It also moistens food, helping to form a bolus—a small, soft mass ready for swallowing.

Cheeks

The cheeks form the sides of the mouth. They are made of muscle and fat, helping with facial expression and chewing. The inside of the cheeks is lined with a mucus membrane that keeps them moist and helps protect against friction during chewing.

Tonsils

Tonsils are small masses of immune tissue located at the back of the mouth. They trap and destroy bacteria, fungi, and viruses that enter through the mouth.

Jaw

The jaw includes the upper jaw (maxilla) and lower jaw (mandible). The mandible is the only movable bone in the skull, allowing the mouth to open and close. It works with the teeth and tongue for chewing and speaking.

Functions of the Mouth

The mouth has several important functions. Each structure plays a role in completing them.

Preparing Food for Digestion

The mouth is responsible for the first stage of digestion. This process includes:

• Breaking down food mechanically:
  The teeth chew and grind food into smaller pieces. This makes it easier to digest later in the stomach and intestines.
• Adding saliva:
  Saliva moistens food, making it easier to swallow. It contains an enzyme called amylase, which begins breaking down carbohydrates in food.
• Forming a bolus:
  The tongue and cheeks work together to form the chewed food into a bolus. The bolus is then pushed to the back of the throat for swallowing.

Speech and Communication

The tongue, lips, and palate work together to produce speech sounds. For example:

• The tongue helps shape sounds by moving against the palate and teeth.
• The lips adjust to pronounce certain letters, such as “m” and “w”.
• These structures are critical for clear communication.

Without the coordinated actions of these components, speaking would be difficult or impossible.

Taste and Sensory Function

The tongue contains taste buds, which identify five main tastes:

• Sweet
• Sour
• Salty
• Bitter
• Umami (savoury)

These tastes help you enjoy food and detect harmful substances. For example, bitterness can indicate that a substance may be poisonous. The mouth is also sensitive to texture and temperature, helping to detect danger, like overly hot food.

Protection

The mouth acts as a barrier to harmful organisms. Saliva contains enzymes and antibodies, such as lysozyme and immunoglobulins, that fight bacteria. The tonsils in the back of the mouth also trap and destroy microbes.

The gag reflex, triggered by the uvula, protects the throat by expelling objects that could obstruct the airway.

Enhancing Facial Expressions

The lips and cheeks play a big role in facial expressions. Smiling, frowning, or pouting are important ways to communicate emotions.

Common Conditions Related to the Mouth

The mouth can be affected by a range of conditions, many of which can impact its function. Some examples include:

• Dental decay: Caused by bacteria breaking down enamel due to poor oral hygiene or a sugary diet.
• Gum disease: Involves inflammation of the gums (gingivitis) or deeper tissues (periodontitis).
• Oral thrush: A fungal infection common in people with weakened immune systems.
• Mouth ulcers: Usually caused by stress, minor trauma, or certain nutritional deficiencies.

Maintaining oral hygiene—like brushing teeth, flossing, and regular dental check-ups—can minimise these risks.

Final Thoughts

The mouth is a combination of structures, each with specific roles. It is responsible for digestion, speech, and protection. By understanding how it works, care workers can help clients maintain oral health and overall well-being.