HUMAN ANATOMY

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HUMAN ANATOMY PHYSIOLOGY
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Human Digestive System
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Warm-Up - journal

1. Write down in correct sequence all the organs (at
   least 5) through which their food passes as it
   travels along the digestive tract.
2. Then try to list any glands or organs that are
   found along the digestive tract, but through
   which food does not pass.

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(No Transcript)
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Following the Digestive Trail
Accessory Organs
Tongue Epiglottis Pharynx (throat) Salivary glands

• Mouth
• Esophagus
• Stomach
• Small Intestine
• Large Intestine

Accessory Organs
Pancreas Liver Gall Bladder
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The Need for Digestion

• Major Functions
• 1. Ingestion - taking in food
• 2. Digestion-ability to process food in the body
  into a form that can be absorbed and used or
  excreted.
• 3. Absorption -pulling nutrients out of the food,
  occurs in the small intestine
• 4. Defecation or Excretion -removal of undigested
  food

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Overview Food processing occurs in four stages
Smallmolecules
Piecesof food
Nutrientmoleculesenter body cells
Chemical breakdown(enzymatic hydrolysis)
Mechanicalbreakdown
Undigestedmaterial
Food
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3
4
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INGESTION
DIGESTION
ELIMINATION
ABSORPTION
Figure 21.2
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A. Purpose

• Provides energy to stay alive
• Process of breaking food particles down into
  molecules small enough to be absorbed by cells
• To help build cells, tissues and organs
• ATP energy for synthesis

B. Why?
mitochondria
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C. Types

• 1. MECHANICAL (Physical)
• takes place in the mouth, your teeth chew the
  food, and the stomach (churning)
• 2. CHEMICAL
• using chemicals to digest/ break down food, this
  takes place in your mouth and stomach where acid
  and enzymes mix with the food.

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Review Nutrition

• Food broken down to usable nutrients and absorbed
  into the bloodstream.
• They are used by the body for metabolism,
  building and repair
• Nutrients include carbohydrates, proteins,
  lipids, vitamins, minerals and water.
• Carbohydrates
• Broken down into monosaccharides
• Bodys main source of energy.
• Proteins
• Broken down to amino acids
• Supply the raw materials for growth and repair.
• Lipids
• Broken down to 3 fatty acids and glycerol
• They are used to make steroid hormones, cell
  membranes
• Store energy

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Nutrient End product (building blocks) Transport
Carbohydrate Simple sugars (glucose fructose) Diffusion (w/out energy high to low)
Proteins Amino Acids Diffusion
Lipids (Fats) 3 Fatty Acids 1 glycerol Diffusion Active transport (with energy, low to high)
Draw/label this
IN Nutrients O2
To the cells
Artery
OUT CO2
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D. Gastro Intestinal Tract

• How is the digestive system similar to a vacuole
  in a one celled organism?
• One celled organism - Digestion is intracellular
  (vacuoles release digestive enzymes)
• Humans- digestion is Extracellular
• (outside the cells then absorbed into the
  bloodstream)

Refer to RB pg 13 table 1-1
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Following the Trail

• Mouth
• Esophagus
• Stomach
• Small Intestine
• Large Intestine

Accessory Organs
Pancreas Liver Gall Bladder
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Mouth
Following the Trail 1

• Functions
• The process begins in the mouth.
• Chewing initiates mechanical breakdown of food
  and is followed by secretion of saliva, which
  moistens and lubricates food for swallowing.
• Saliva also contains amylases (enzymes), which
  start the chemical breakdown of carbohydrates.

All thatin spit!
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Esophagus
Following the Trail 2

• The swallowing reflex begins in the pharynx and
  initiates rhythmic waves of smooth muscle
  contractions called peristalsis.
• Brings food from mouth to stomach
• Food is now called a BOLUS
• Epiglottis
• Flap of tissue at back of throat that prevents
  food from entering the wind-pipe
• Peristalsis
• Wave-like contractions that move bolus to stomach
  
• Peristaltic contractions transport food to the
  stomach and allow a person to swallow even if
  he/she are upside down.
• Click Here for animation

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Stomach
Following the Trail 3
But the stomach is made out of protein! What
stops the stomach from digesting itself?
mucus secreted by stomach cells protects stomach
lining

• Functions
• Continued mechanical digestion of Carbohydrates
  (churns)
• First PROTEIN digestion uses pepsin (enzyme)
• Bolus turned to CHYME
• disinfect food
• hydrochloric acid pH 2
• kills bacteria
• food storage- can stretch to fit 2L food

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Small intestine
Following the Trail 4
Small intestine has 3 parts

• Functions
• The small intestine completes digestion of food
  materials by absorbing nutrients into the blood
  stream
• S.I. lined with tiny folds or fingerlike
  projections, called villi, which, in turn, are
  covered by microvilli which increase surface area
• The villi contain capillaries and lymphatic
  vessels for the absorption of nutrients
• Nutrients move into blood stream by what process
  (Think H to L!)? DIFFUSION!!!!!!!!!
• Chemical digestion only
• Continued digestion of Carbohydrates
• Continued digestion of Proteins
• First FAT digestion

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Absorption in Small Intestines
Following the Trail 4 cont.

• Absorption through villi microvilli
• increases surface area for absorption

Cross-Section of small intestine
Microvilli
Villi
SMALL INTESTINES6 meters long,but can
stretchto cover a tennis court
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Following the Trail 4 cont.

• As food enters the small intestine secretions
  from the liver, gall bladder and pancreas are
  added .

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Pancreas
Following the Trail 4 cont.

• Produces digestive enzymes
• Buffers
• neutralizes acid from stomach

pancreas
smallintestine
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Balancing Blood Sugar levels
Homeostasis
insulin
body cells takeup sugar from blood
liver storessugar
reducesappetite
blood sugar level
liver releasessugar
triggershunger
Feedback
glucagon
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Liver Gall Bladder
Following the Trail 4 cont.

• Produces bile
• breaks up fats
• gallbladder only stores bile
• (thats why you can have your gall bladder
  removed)

FYI - bile contains colors from old red blood
cells collected in liver iron in RBC rusts
makes feces brown
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Large intestines (colon)
Following the Trail 5

• Function
• The large intestine does not contain villi and it
  plays no role in digestion
• Removes WATER from undigested chyme
• Lined with bacteria (E. coli)
• Only water and vitamin K are absorbed from the
  large intestine
• Undigested or unabsorbed food is eliminated
  through the rectum and then anus.

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Rectum

• Last section of large intestines
• eliminate feces
• whats left over?
• undigested materials
• mainly cellulose from plants called roughage or
  fiber
• keeps everything moving cleans out intestines
• masses of bacteria
• Final stop for undigested materialthe anus!

So dont forget to wash your hands!
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Where does each nutrient get broken down?
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Carb- Digestion Protein Digestion Nucleic Acid Digestion Fat Digestion
Mouth, Throat, Esophagus Polysacch. Into Disacch.
Stomach Polypepties into smaller proteins DNA, RNA into nucleotides Fat into glycerol, fatty acids and glycerides
Small Intestine Disacch. Into Monosacch. Small proteins into amino acids Nucleotides into nitrogen base, sugar and phospate
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What enzymes break down each nutrient?
Carb Digestion Protein Digestion Nucleic Acid Digestion Fat Digestion
Salivary amylase (amylose is starch, a polysacch) Peptidases (amino acids are connected by peptide bonds) Nucleotidases (nucleotides are building block of DNA and RNA) Bile salts and Lipase (fats are made of lipids)
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E. Digestive Homeostasis Disorders
Body Invaders Digestive Problems Video
Discovery Health

• 1. Stomach
• 1) Mucus that prevents stomach from digesting
  itself
• a) Peptic ulcer occurs when layer of mucus fails
  (open sores)
• b) Gastric juices reach wall of stomach and begin
  to break down (painful)
• 2) Treatment
• Before Antacid would reduce amount of acid in
  stomach but would return
• Recently Ulcer is an infection by acid resistant
  bacteria Helicobacter pylori
• Treatment antibiotics

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• 2. Appendix
• No function may have once been used to digest
  plants (vestigal organ)
• Appendicitis inflammation of the appendix
  caused by E. Coli bacteria

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3. Large Intestine

• Constipation- too much water reabsorbed from the
  feces
• Diarrhea-too little water reabsorbed from the of
  feces prolonged diarrhea can cause dehydration
  of body tissues.

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4. Colon Cancer

• One of the most common types of cancers in North
  America
• Colon section before the rectum on lg.
  Intestine
• Cause
• Diet low in fiber causes feces to move too slow
  through colon
• Hereditary predisposition

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5. Gallstones

• small hard stones made of cholesterol that
  collect in the gallbladder.
• Due to a high saturated fat diet
• hereditary

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mouth ?break up food ?digest starch ?kill
germs ?moisten food
stomach ?kills germs ?break up food ?digest
proteins ?store food
liver ?produces bile - stored in gall
bladder ?break up fats
small intestines ?breakdown food - proteins -
starch - fats ?absorb nutrients
pancreas ?produces enzymes to digest proteins
carbs