Nutrition &Digestion - PowerPoint Presentation

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Nutrition &Digestion

Ass.Prof.Dr

. Suhad Faisal

Hatem

Nutrients : substances obtained from the environment that organisms need for growth ,repair ,regulation and survival.

Six type of nutrients help to

maintain

homeostasis CarbohydratesLipidsProteinsMineralsVitaminsWater

Most energy is provided by carbohydrates and fatsCells rely on a supply of energy to maintain their activities,Nutrients that supply energy are lipids, carbohydrates, proteins. Energy in food is measured in a unit called a CalorieBroken down by digestion to their subunits, which are used during cellular respiration,Energy from these subunits is released and is captured in ATP

Micronutrients : Nutrients the body needs in relatively small amounts are called Micronutrients. They include vitamins and minerals.

Macronutrients :

Nutrients

the body needs in relatively large amounts are called macronutrients. They include carbohydrates, proteins, lipids, and water

1-Carbohydrates Functions

Energy

source for plants and

animalsSource of carbon in metabolic processesStorage form of

energyStructural elements of cells and tissuesOne gram of carbohydrates provides 4 Calories of energy.

1-Carbohydrates a source of quick energy

glucose

,

sucrose (simple carbohydrate )polysaccharides, long chains of sugar molecules Cellulose, starch, and glycogen are polysaccharides composed of glucose chains (complex carbohydrate)

Cellulose - structural component of plant cell wallsStarch -storage material of plantsGlycogen - used by animals for short-term energy storage.it is converted glucose by body

Essential Nutrients Provide raw materials

Our

cells can synthesize most of the molecules our bodies require, but they cannot synthesize certain raw materials, called essential nutrients, which must be supplied in the

dietEssential Nutrients for humans include certain

fatty acids, amino acids, a variety of minerals, vitamins,

water

Essential Fatty Acids:Certain

fatty acids are essential in the human

dietFats and oils provide a source of energy and essential fatty acidsSimilar to carbohydrates but include less O2 and not dissolved in water

They help us absorb fat-soluble vitamins, are important in cell division, fetal development, and immune responseSources of essential fatty acids are fish oils, canola oil, soybean oil, flaxseed, walnutsOne gram of lipids provides 9 Calories of energy

Lipdes

Protein Function

Protein from

food is broken down into its amino acid subunits, which can be used to synthesize new

proteins.Composed from C ,H,O,N to form amino acidsused for the growth and repair of the body’s cells and tissuesProtein functions in the body -*:enzymes, receptors on cell membranes

, oxygen transport molecules, structural proteins, antibodies, muscle proteinsProtein-rich foods - meat, milk, eggs, corn, beans, soybeansOne gram of proteins provides 4 Calories of energyEssenssial amino acids 

•

Proteins are composed of chains of amino acids. Your body can make only 12 of the 20 amino acids it needs to build proteins. The other 8, called essential amino acids, must come from the food you eat

.

•

Food such as meat, cheese, and eggs contain all eight essential amino acids.

VitaminsIt organic molecules that animals require in small amounts for normal cell function, growth,

development and

Help change carbohydrate and fats to energy

Vitamins are required for the proper functioning of enzymes that control metabolic reactions in the bodyVitamins are essential nutrients that the body cannot synthesize and must be obtained in the dietThey are grouped into two categories: water soluble or fat soluble

Minerals

Elements

that play a role in animal nutrition and can only be obtained in diet or drinking

waterCalcium, magnesium, and phosphorus are components of bone and teethSodium, calcium, and potassium - needed for muscle contraction and nerve impulses Iron - hemoglobin in the blood Iodine - hormones produced by the thyroid gland

Major Minerals includes Calcium, magnesium, phosphorus ,Sodium, and potassium Trace Minerals includes Iron, Iodine,Zinc,Copper

Water :The

human body is about 60%

water

carries dissolved nutrients by our body and help in digesting foodAll metabolic reactions occur in solution, and water participates directly in hydrolysis reactions that break down proteins, carbohydrates, fats

Water is the principal component of saliva, blood, lymph, extracellular fluid, and cytoplasmic fluidBy sweating, evaporation of water , prevent over heating

Urine

, mostly water, is necessary to eliminate cellular waste products

Weight Gain and Obesity Any unused energy in food, whether it comes from carbohydrates, proteins, or lipids, is stored in the body as fat

.

An extra 3,500 Calories of energy results in the storage of almost half a kilogram (1 pound) of stored body fat. People who consistently consume more food may become obese. Obesity occurs when the body mass index is 30.0 kg/m2 or greater. Body mass index (BMI) is an estimate of the fat content of the body. It is calculated by dividing a person’s weight (in kilograms) by the square of the person’s height (in meters). Obesity increases the risk of health problems such as type 2 diabetes and hypertension.

Digestion

is

the process by which the large complex molecules in food are broken down into smaller molecules that can be used by the body. • The digestive system

includes the gastrointestinal tract and the associated glands.Ingestion: the process of taking in food into the digestive tract through an opening, usually called a mouth is known as ingestionDigestion consists of two types of processes1- Mechanical breakdown: The process of breaking down food into smaller pieces by teeth and tongue mixed food with saliva (contains bacteria-killing enzyme and antibodies).

Also the mucus help food to move from throat to stomach using muscle movement called peristalsis.2- Chemical breakdown: The particles of food are acted upon by enzymes that break them down into simpler subunits.

4- Digestion in Stomach Stores food and releases it gradually into the small intestine,

Stomach helps in the

mechanical breakdown

of large pieces of food and Chemical breakdownGastric fluid includes:1-Pepsinogen (inactive)------------ Pepsin -------Proteins --------Peptides.2- HCL :Activates inactive pepsinogen into active pepsin. • Kills bacteria. • Makes the medium acidic which is suitable for pepsin to act on proteins

.3- The stomach secretes a layer of mucus to protect itself from its own acidic Sphincters : circular muscles help food movement in and out stomach (pyloric & cardiac)Digested juices and enzymes turn the partly digested food in the stomach into a semi liquid mixture called chyme food takes six hours to empty the stomach after a meal.water&alchohol will be absorbed in stomach

5- Absorption: The main function of small intestine is to digest food and absorb the digested food into the bloodstream with liver and pancreas. Absorption occur in small and large intestine

Small intestine

: include

bile juice & pancreatic juice & digestive enzymes 1- bile juice Liver secretes bile which is stored in the gall bladder and released when needed through the bile duct, Bile helps in emulsification of fats.2- pancreatic juice : neutralizes

the acidic chyme and enzyme digests carbohydrates, proteins and lipids. Pancreatic proteases(trypsin): break down protein into peptides , Pancreatic lipases break down fats into fatty acid and glycerol.3-Digestive Enzymes • The walls of the small intestine secrete digestive enzymes to digest food. • Peptidases to split small peptides into amino acids. • Maltase acts on maltose and converts it into glucose. • Sucrase acts on sucrose and converts it into glucose and fructose. •

Lactase acts on lactose and converts it into glucose and

galactose

.

•

Lipases acts on lipids and convert it into fatty acid and glycerol.

The small intestine has numerous folds and projections (Villi ) that give it an internal surface area

.

•

Villi :Minute finger like projections cover the entire folded surface of the intestinal wall. Each individual cell of the villi bear microscopic projections called microvilli. Each villus of the small intestine is provided with a rich supply of blood capillaries that absorbed nutrient except large fat molecules and distribute them throughout the body• Nutrients absorbed by the small intestine include water, monosaccharides, amino acids and short peptides, fatty acid produced by lipid digestion, vitamins and minerals.

The end of the large intestine is the

rectum

(

short term storage which holds feces before it is expelledLarge intestine • It has two parts, colon and rectum.

• The large intestine has bacteria which live on unabsorbed food. • The intestinal bacteria can synthesize vitamin B12, thiamin, riboflavin and Vitamin K. •

Cells lining the large intestine absorb these vitamins and water

, salts and

concentrate waste

•

After absorption is complete, any remaining material is converted into semisolid

feces.

6

-Elimination/egestion

: In

digestable

materials must be expelled from the body.

Accessory gland

1-Pancrease:

organ secreted enzyme &hormones

Exocrine pancreas produces NaHCO, Amylase,Trypsin, lipaseEndocrine pancreas produces insulin &glucagon2-liver :organ effects on digestion by producing bile Regulate cholesterol by bile salts(green fluid)Detoxify blood , store iron , vitamins A D E KConvert excess food to form can be stored

Filters out toxins and waste including drugs, alcohol and poisons3-Gall bladder: Structure located near liver store the bile ,bile will break fats and make it emulsifies

Thank You