The Building Blocks of Nutrition

• The energy needed for life, creature development, and growth relies on raw materials and their actions.
• The human body can not directly use food.
• The digestive system turns food into molecules that cells absorb.
• This process enables cells participation in metabolic processes.
• The body receives nutrients from the environment.
• The processes of breaking down food happen in the cells and are then absorbed into the blood in the process of digestion.
• Different processes occur in cells, transforming food into essential components.
• The digestive system breaks down food into vital building blocks, which are used in metabolic processes within cells.
• The body's building materials are proteins, making up 18% and are found in small quantities in the tissues of the cells
• The body's chemical processes are dependent on minerals like magnesium, phosphorus, calcium, sulfur, chlorine, sodium, and potassium.
• Vitamins are needed by the body in minor quantities.
• Fats are vital for all living things, serving energy resource and maintaining cell membrane integrity
• Carbohydrates are the primary source of energy for the body, for energy production and cell structure

Food Pyramid

• The food pyramid provides a basis for a healthy lifestyle with physical activity.
• It recommends minimizing sweets, snacks, and sweet drinks.
• Moderation in fats, proteins, fruits, and vegetables should be followed.
• The need for cereals and water, as well as physical activity should be increased.

The Digestive System

• The digestive system is a long, twisted tube within the body that is open at both ends to the external environment.
• It spans approximately 9 meter in length
• It begins with a tube at the mouth and is considered an external system whose contents vary of the body.
• Digestion component depends on quality and quantity

Digestive System Components

• The main parts of the digestive system start at the mouth ending in the large intestine, and includes the esophagus, stomach, duodenum, and small intestine
• Accessory components include the liver, pancreas, gallbladder, and bile.
• Food enters the digestive tract through the mouth and advances by muscle contractions in waves (peristalsis).
• Digestion breaks down food into chemical units for the body by enzymes, hydrochloric acid (HCl), and bile salts.
• The body eliminates the waste

The Mouth

• The mouth is the digestive system's first stop where three things occur.
• Mechanical breakdown breaks food into smaller particles through chewing.
• Food is reduced into smaller fragments
• The saliva, secreted by the salivary glands, moistens and softens food helping create a soften mass.
• Digestion continues, allowing enzymes chemical starch breakdown.
• Carbohydrate breakdown begins in saliva, with complex sugars (polysaccharides) broken into simpler sugars (disaccharides).
• Further monosaccharide breakdown happens in the intestine.

Increasing Surface Area

• Digestion creates smaller pieces with enzymes, increasing the surface area.

Saliva Facts

• In digestion the tongue assists in food smoothing and softening, acting as a dissolvent.
• Salvia is 90% water and Ions, and the neutral pH helps in chewing by acting as a transferring agent
• Saliva contains enzymes like amylase and lysozyme to help breakdown process
• With Saliva, amylase enzyme begins the starch (polysaccharide) breakdown into simpler sugars (disaccharides).
• Mouth enzymes function best in a neutral setting.
• The body excretes about 1.5 liters of saliva each day.

The Esophagus

• The Esophagus transports food from the mouth to the stomach with a mucous membrane.
• During chewing, food passes through the esophagus in seconds.
• The esophagus acts as a transit point, and is coordinated with the respiratory system
• Trachea opening closes during food swallowing, alloweing pharynx entry.
• The walls of the esophagus consist of muscles, contractings and relaxing to push the food downward in the stomach.
• This wave-like motion, is called peristalsis

The Stomach

• The stomach serves as a large pouch on the left side of the body under the diaphragm, has 2-3 liters in volume.
• A valve at the side opens to the esophagus, referred to as the pyloric sphincter which is a muscle ring.
• Another side opens to the duodenum, and when the ring muscle, preventing food from moving back into the stomach.
• Before food storage, is undergoes breakdown by stomach enzyme pepsin and gastric juices.
• Protein digestion begins in the stomach within an hour.
• A pyloric sphincter will close and open as needed
• The structure is thick containing three muscle layers with circular, longitudinal, and oblique contraction.
• Stomach secretes juices for food digestion, folded with cavities

Specialized Valves in Stomach

• These Valves allow adjustments to the surface and function as structural support
• Large amounts of acid are secreted along with HCI which help in this process

Special Stomach Wall

• The wall is built on a fat base. Proteins in the wall that are muscle are controlled to prevent a self digestive process

Gastric Juice

• The Stomach's juice fills stomach walls cells, very acidic at 1.5–2 pH level.
• That level is the minimal required to create an acidic environment.
• Stomachs acid acts to breakdown proteins with enzymes (pepsin)
• The acid helps destroy bacterial and avoids proliferation of unwanted bacteria.
• Gastric juices amount is generally at 2.5 liter secreted per day.
• Chemical breakdown of protein occurs here in the mucus layer
• Stomach juice with mucus and Hydrochloric acid activates an enzyme called pepsin to convert chains
• Amino acids break the digestive chains down

Protecting the Stomach

• The stomach, constructed primarily from proteins, survives the chemical processes as the acidic in in the stomach would be destructive to those cells
• Instead the stomach wall is lined with mucus layer.
• Enzymes are not immediately activated but only in the presence of other proteins and factors.

The Duodenum

• The Duodenum starts the small intestine functioning at 25 cm.
• Food travels from stomach through the pylorus.
• Carbohydrates, proteins are digested with the help of enzymes, the result of two organs: pancreas and liver.

Secretions

• Mucous layer produced by its glands protect the stomach walls and neutralizes acidity.
• Basic Secretions are primarily produced by gall bladder.
• Bile will emulsify fat by reducing the droplet size .
• The small intestine contains enzymes secreted into the duodenum like: Starch, protein and lipids.

Lipid Breakdown

• Substance emulsion consists of fat of small droplets.
• When salts exist, large droplets do not mix well, but bond to existing molecules to help the process of droplet breakdown
• Fat become emulsified to help further digestion.

Fat Breakdown Optimization

• Breaking down fat is optimized via increasing triglycerides by the surface of the fat
• As a result enzymes efficiently increase volume of the surface area.
• Key processes occuring the thin intestine, include: Where chemical digestion, absorption happen, it primarily occurs in digestion.
• Digestive juices break components down and nutrients get absorbed through the walls into the blood.
• Absorption is the full length of the small intestine primarily.

The Thin Intestine's Structure

• The duodenum is the part of the small intestine that connects to the liver for digestion
• Building block units or nutrients are absorbed in the small intestine.

Increased Area

• Large, numerous cell contact area helps increase surface area .

Absorption Surface Area Details

• Absorption area is highly impacted by folds on the microvilli and the internal wall .
• Higher speeds of absorbing blood and intestinal contents increase nutrient intake efficiently , prevent de hydration and help intake of water by 7.5 liter daily .

Enzymes in Intestines

• Carbohydrates is broken into sugars, amino acids is split by fat enzymes with production of glycerol.

Creature development and growth depend on raw materials. The digestive system converts food into molecules for cell absorption, enabling metabolic processes. The body receives nutrients from the environment, and cells transform food into essential components.