chapter 14 part b

Chapter 14: Digestive System & Nutrition: Part B

1.     Accessory organs

a.    Teeth

b.    Salivary glands

c.    Pancreas

d.    Liver

e.    Gall bladder

2.    Teeth classification

a.    Incisors-cutting

b.    Canines-tearing or piercing

c.    Premolars-pre-grinding

d.    Molars-grinding

3.    Salivary glands – three pair

a.    Parotid-largest, near ear

b.    Submandibular-under jaw

c.    Sublingual-under tongue

d.    Saliva

                                          i.    Mixture of…

1.     Mucus

2.    Serous

                                        ii.    Helps to form a food bolus

                                       iii.    Contains salivary amylase to begin starch digestion

                                       iv.    Dissolves chemicals so they can be tasted

4.    Deglutition = swallowing

a.    Buccal phase- voluntary, occurs in mouth, food is formed into a bolus, the bolus is forced into the pharynx by the tongue.

b.    Pharyngeal-esophageal phase

                                          i.    Involuntary transport of the bolus

                                        ii.    Passageways blocked: tongue blocks off the mouth, soft palate (uvula) block nasopharynx, epiglottis blocks the larynx

                                       iii.    Peristalsis moves the bolus toward the stomach

                                       iv.    Cardio-esophageal sphincter is opened when food presses against it

5.    Pancreas –found posterior to the parietal peritoneum, extends across the abdomen from spleen to duodenum

a.    Produces a wide spectrum of digestive enzymes that break down all categories of food

b.    Secretes enzyme into the duodenum

c.    Alkaline(basic) fluid introduced with enzymes neutralizes acidic chime coming from stomach

d.    Hormones in the pancreas:

                                          i.    Insulin-lowers blood sugar; sugar into cells

                                        ii.    Glucagon-raises blood sugar; liver; glycogen

6.    Liver

a.    Size- largest internal gland/organ

b.    Location on the right side of the body under the diaphragm

c.    Consists of four lobes suspended from the diaphragm and abdominal wall

d.    Connected to the gallbladder through the common hepatic duct

e.    Produces bile

                                          i.    Salts

                                        ii.    Pigments

                                       iii.    Function

7.    Gall bladder

a.    Structure & location-sac found in hollow fossa of liver

b.    When no digestion is occurring, bile backs up the cystic duct for storage in the gallbladder

c.    When digestion of fats is occurring, bile is introduced into the duodenum from the gallbladder

d.    Gallstones are crystallized cholesterol which can cause blockages

8.    Functions to accomplish digestion

a.    Ingestion-getting food into the mouth

b.    Propulsion-moving foods from one region of the digestive system to another

c.    Peristalsis-alternating waves of contraction and relaxation that squeezes food along the GI tract

d.    Segmentation-moving materials back and forth to aid with mixing in the small intestine

e.    Mechanical digestion

                                          i.    Mixing food in the mouth by the tongue

                                        ii.    Churning food in the stomach

                                       iii.    Segmentation in the small intestine

                                       iv.    Mechanical digestion exposes surface area of food for further breakdown by enzymes

f.    Chemical digestion- food breakdown

                                          i.    Enzymes break down food molecules into their building blocks

1.     Carbohydrates are broken to simple sugars

2.    Proteins are broken to amino acids

3.    Lipids are broken to fatty acids and alcohols

g.    Absorption

                                          i.    End products of digestion are absorbed in the blood or lymph capillaries (thin walls)

h.    Defecation-elimination of indigestible substances from the GI tract in the form of feces

                                          i.    Feces

                                        ii.    Also bacteria, bile pigments

9.    Nutrition

a.    Nutrients (food)- substance used by the body for growth, maintenance, and repair

                                          i.    Major nutrients

1.     Carbohydrates: sugars, starches= energy. Most are derived from plants. Exceptions: lactose from milk and small amounts of glycogens from meats.

2.    Lipids: fats, oils, waxes= energy, structure. Saturated fats from animal products. Unsaturated fats from nuts, seeds, and vegetable oils. Cholesterol from egg yolk, meats and milk products

3.    Proteins= energy, structure, enzymes. Complete proteins- contain all essential amino acids. Most are animal products. Legumes and beans also have proteins, but are incomplete.

4.    Water=no energy, body solvent

                                        ii.    Minor nutrients

1.     Vitamins: coenzymes, metabolism

2.    Minerals: inorganic, assist physiology, anatomy

b.    USDA food guide pyramid