Digestive System Walkthrough Powerpoint
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Transcript of Digestive System Walkthrough Powerpoint
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Digestive System Digestive System Walkthrough Walkthrough
November 18 2008 Mark Ealy
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Digestion Digestion
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Digestion Digestion and its 3 Functions and its 3 Functions
Digestion is the process of breaking larger food particles into smaller particles that can pass through the plasma membrane.
Every cell in the body needs nutrients Absorption- The circulation of nutrients in
the bodyElimination- Undigested waste material
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Digestive Tract
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Mouth/ Oral Cavity Mouth/ Oral Cavity
Receives Food Breaks food into smaller particles by
chewingSalivary glands in the mouth secrete saliva to
help lubricate the food Saliva also has a digestive enzyme named
Salivary amylase, which jump starts starch digestion
Tongue aids in chewing and swallowing and is a muscular organ, that contains taste buds that differentiate taste of different foods.
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TeethTeeth
Also housed in the mouth/oral cavity. 32 in a complete set for adults Are used to break food down into smaller
particles for absorption Covered in enamel the hardest substance
in body to keep
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Pharynx/ Throat Pharynx/ Throat
Separated into parts Oropharynx- contains the tonsils and is
visible when you look into the mouthNasopharynx – upward to the nasal cavity Laryngeal Pharynx- Downward Extend The Tongue pushes food into the pharynx,
swallowing is involuntary and happens quickly
Soft Palate and uvula raise to prevent food from entering nose cavity
Food enters Esophagus
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Esophagus Esophagus
Muscular Tube Measuring about 25 cm No additional digestion occurs in the
esophagus Food is lubricated with mucus and moved
by peristalsis into the stomach Must pass through the Esophageal Hiatus
located in the Diaphragm before connecting with the stomach
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Stomach Stomach
J Shaped organ in upper left region of the abdominal cavity.
Has an Angled layer that aids in the grinding of food and mixing of digestive juices.
Contains Sphincters that regulate the size of the opening
Pylorus- Leads to the sphincter that regulates how fast food moves into the small intestines
Functions as a digestive organ, churn, and storage pouch.
Can stretch to hold one half of a gallon of food or water Gastric Juice formed by special cells in the lining of the
stomach
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Stomach Cont.Stomach Cont.
Active components of Gastric Juice are :Hydrochloric acid- strong acid that helps break
down protein and destroy foreign organisms Pepsin- Inactive form of protein digesting enzyme
only activated when food enters stomach and HCl is produced
Chyme- Highly Acidic , mixture of gastric juice and food that leaves stomach and enters small intestine.
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The Small Intestine The Small Intestine
Longest part of digestive tract! Larger than larger intestines but smaller in diameter average width of
2.5 cm Duodenum- first 2mcm of the small intestines Jejunum- next 2/5 cm Ileum- the remaining portion Mucus protect the intestine from the highly acidic chyme from the
stomach. Most digestion occurs here, due to the juices secreted by many
glands that help aid in the breakdown of carbs and proteins. Most absorption of digested food, water, and minerals also occur
here. Microvilli- increase the surface area of absorption in the small
intestines Contains a specialized lymphatic capillary called a lacteal, which
absorbs fats.
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The Large Intestine The Large Intestine
Named for its wide diameter Cecum- first part small pouch Ileocecal valve- between the ileum of the small intestines a
sphincter that prevents food from traveling backward into the small intestines
Veriform- blind tube containing lymphoid tissue Contains the colon that empty in the rectum Rectum- temporary storage area for indigestible or
nonabsorbable food Narrows into the anal canal, which leads to the outside of
the body called the anus
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The Large Intestines Cont. The Large Intestines Cont.
Secretes a great amount of mucus, but no enzymes.No food is digested, but some water is reabsorbed
and undigested food is stored and formed into solid waste, called feces and eliminated
Propels solid waste toward the rectum , aided by voluntary contractions defecation is achieved.
Contains an anal sphincter that provides voluntary control over defecation
Some bacteria that live in the colon produce vitamin k and some B complex vitamins
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The Accessory Organs The Accessory Organs
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The Salivary Glands The Salivary Glands
Food mixes with salvia in the mouth which moistens the food and facilitates chewing and swallowing
Contains antibodies and lysozyme that help reduce bacterial growth
Contains salivary amylase which begins the digestive process by converting sugar to starch.
Manufactured in 3 pairs of glands.
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Liver Liver
Body's largest glandular organ Manufactures bile- substance needed for digestion of fats Stores Glycogen and coverts it to glucose to restore normal
blood sugar levels Stores some vitamins and iron Destruction of red blood cells and recycling or elimination
of their breakdown products Synthesis of urea- waste product of protein metabolism Detoxification of harmful substances such as alcohol and
drugs The main digestive function of the liver is the production of
bile, breaks fats into smaller droplets that can be acted upon by digestive enzymes
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The Gallbladder The Gallbladder
Muscular sac on the inferior surface the liver that stores bile
Contracts and squeezes bile through the cystic duct and into the common bile duct, when chyme enters the duodenum
Stores bile because the body only needs it a few times a day.
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The Pancreas The Pancreas
Long gland that extends from the duodenum to the spleen Produces enzymes that digest fats, proteins, carbohydrates,
and nucleic acids Protein digesting enzymes are produced in inactive form and
must be converted into active forms in the small intestines Produces Alkaline fluid, that balances the acidic chyme
protecting the lining of the SI Can also function as an endocrine gland, producing insulin and
glucagon to regulate sugar metabolism
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Enzymes/ WaterEnzymes/ Water
Enzymes are proteins that are catalyst, that speed the rate of chemical reactions
Highly Specific in its action Water – is added to nutrient molecules as they are split by
enzymes. Hydrolysis- digestion by water 7 liters of water are secreted into the digestive tract each
day, in addition to 2 liters taken in with food and drink Helps dilute food to move more easily through tract
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Hormones Active In Digestion Hormones Active In Digestion
Gastrin- Stimulates release of gastric Juice Gastric-Inhibitory Peptide- Stimulates insulin release from
pancreas when glucose enters duodenum; inhibits release of gastric juice
Secretin- Stimulates release of water and bicarbonate from pancreas, stimulates release of bile from liver: inhibits the stomach
Cholecystokinin- Stimulates release of digestive enzymes from pancreas, stimulates release of bile from gallbladder inhibits the stomach.