Nutrition

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Nutrition Digestive System
Homeostasis
Process by which organisms maintain a relatively
stable internal environment.
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Food and Nutrition

• Why do we eat food?
• Cells convert chemical energy stored in the sugar
  glucose and other molecules into ATP.
• Energy in food is measured by the amount of heat
  given off by the food. We measure this in
  calories. One calorie is the amount of heat
  needed to raise the temperature of one gram of
  water by 1 degree Celsius.
• Calorie (capital C) is the energy stored in food.
  One Calorie is equal to 1000 calorie or 1
  kilocalorie kcal.

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Nutrients

• Nutrients- Substances in food that supply the
  energy and raw materials your body uses for
  growth, repair and maintenance.
• The nutrients that the body needs are
• Water, Carbohydrates, fats, proteins, vitamins,
  and minerals
• Water is the most important of all!
• Every cell in the human body needs water because
  of many of the bodys processes.

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Nutrients continued

• Carbohydrates- Main source of energy for the
  body. Sugar found in fruit, honey and sugar can
  are simple carbohydrates.
• Monosaccharides and disaccharides
• Complex carbohydrates those found in pasta,
  potatoes and other starches
• Polysaccharides
• Fats or lipids. Fats are formed from fatty acids
  and glycerol. Your body cannot make all the
  fatty acids it needs. These can be found in
  vegetable oils.
• Fats are used to produce cell membranes

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Dehydration Synthesis of a Disaccharide
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Hydrolysis of a Disaccharide
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Fatty Acid Structure
Fatty Acid

• Carboxyl group (COOH) forms the acid.
• R group is a hydrocarbon chain

Synthesis of a Fat
Glycerol
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Nutrients continued

• Proteins- supply raw materials for growth and
  repair of structures such as skin and muscle.
  Proteins have regulatory and transport functions.
• Insulin controls sugar levels
• Hemoglobin transports oxygen
• Another example of maintaining homeostasis!
• Examples of proteins? (Contains Nitrogen)
• Vitamins- Organic molecules that help regulate
  body processes, often working with enzymes.
• Minerals- Inorganic nutrients that the body
  needs, usually in small amounts.
• Organic vs Inorganic?
• Organic contains Carbon and Hydrogen

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Proteins

• What are the building blocks of proteins???
• Amino Acids!

Formation of a Dipeptide
Dehydration synthesis
Amino group
Carboxyl group
Alanine
Serine
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Organic not organic?

• CO2 ____________
• H2O _____________
• C6H12O6 ________________
• HCl ______________

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Process of Digestion

• Purpose of digestion- break food down into small
  molecules that can be passed to the cells that
  need them
• The digestive system includes the mouth, pharynx,
  esophagus, stomach, small intestine, and large
  intestine.
• Accessory structures are salivary glands,
  pancreas, and the liver. They add secretions to
  the digestive system.

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Mouth

• Digestion starts in the mouth with mechanical
  digestion with chewing.
• Also chemical digestion happens here with
  digestive enzymes.
• Teeth mechanical digestion cutting tearing and
  crushing food.
• Saliva- Created by salivary glands, moisten food
  make it easier to chew. Contains enzyme amylase.
• Amylase- breaks chemical bonds between the sugar
  monomers in starches.

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How do human teeth reflect an omnivorous diet?
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Esophagus

• Esophagus- Food tube into the stomach.
• The reason food can travel through the esophagus
  into the stomach is because of peristalsis. Food
  is moved along by contractions of smooth muscle
  surrounding the esophagus.
• Peristalsis- Rhythmic muscular contractions that
  squeeze food through the esophagus into the
  stomach.

http//www.nlm.nih.gov/medlineplus/ency/anatomyvid
eos/000097.htm
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Stomach

• Stomach is a large muscular sac. The size enables
  you to eat a few large meals a day.
• Mechanical digestion in the stomach
• Contractions of its smooth muscles churn and mix
  the food you swallow.
• After churning and mixing stomach fluids and food
  it becomes chyme.
• Chemical digestion in the stomach
• The lining of the stomach contains millions of
  microscopic gastric glands that release
  substances.
• Some produce mucus others hydrochloric acid.
• Very acidic which activates pepsin. Pepsin is an
  enzyme that breaks down proteins.

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More about the stomach

• Powerful acids released into the stomach can
  sometimes damage the lining producing a hole.
  This would be a peptic ulcer. Usually peptic
  ulcers caused from bacteria not stomach acid.

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Pancreas and Liver

• As chyme is pushed from the stomach to the small
  intestine it first enters the duodenum. The first
  of three parts of the small intestine.
• Small intestine is the location where most of the
  chemical digestion happens. As chyme enters the
  duodenum is mixes with enzymes and digestive
  fluids from the pancreas and liver.

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Pancreas and Liver

• Pancreas- Has 3 important functions (2 for
  digestion)
• 1. Produce hormones that regulate blood sugar.
• 2. Produces enzymes to break down carbs,
  proteins, lipids, and nucleic acids.
• 3. Produces sodium bicarbonate, a base which
  neutralizes stomach acid. Allows enzymes to work.
  Acid can change the shape. (lock and key)
• Liver- Produces bile, a fluid loaded with lipids
  and salts. Dissolves the droplets of fat found in
  fatty foods. Bile is stored in the gallbladder.

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Small Intestine

• The small intestine absorbs NUTRIENTS. The
  folded surfaces of the small intestine are
  covered with projections called villi.
• The surfaces of the cells of the villi are
  covered with thousands of fingerlike projections
  known as microvilli.
• LOTS OF SURFACE AREA!!
• More surface area allows absorption of nutrients.

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Large Intestine aka colon

• Is shorter, but wider, than the small intestine.
• The main job of the large intestine is to remove
  water from the undigested material that is left.
• Colonies of bacteria grow on the undigested
  material left in the colon that help with the
  digestive process.

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The Excretory System
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Excretion

• Every cell in the body produces metabolic wastes
  to maintain homeostasis the body must rid of the
  waste products.
• Excretion is the process by which metabolic
  wastes are eliminated.
• Organs Skin, lungs, and kidneys are the main
  components of the excretory system.

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The Kidneys

• Main organs involved with excretion are the 2
  kidneys.
• A tube called the ureter leaves each kidney
  carrying urine to the urinary bladder where it is
  stored.
• The kidneys remove urea, excess water, and other
  waste produces from the blood and is collected as
  urine.
• Cleans the blood! Filtration.

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Control of kidney function

• The kidneys play an important role in maintaining
  homeostasis.
• They regulate the water content of the blood,
  volume, pH level and remove waste products from
  blood.

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