Digestive System Learning Targets 1-5 1.Trace the path of food in the digestive tract & describe the...
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Transcript of Digestive System Learning Targets 1-5 1.Trace the path of food in the digestive tract & describe the...
Digestive SystemLearning Targets 1-5
1. Trace the path of food in the digestive tract & describe the general structure & function of each organ mentioned
2. Describe peristalsis & state its function.3. Describe the wall of the small intestine & relate
its anatomy to nutrient absorption.4. Name the hormones produced by the digestive
tract that help control digestive secretions.5. Name the accessory organs of digestion &
describe their contributions to the digestive process.
Trace the path of food in the digestive tract & describe the general structure & function of each organ mentioned (LT#1)• Mouth
• Pharynx• Esophagus• Stomach• Small intestine• Large intestine• Rectum• Anus
The mouth (oral cavity) (LT#1)• Bounded by lips, cheeks, palate,
and tongue • Continuous with the oropharynx
posteriorly• pg 299• Carbohydrate digestion starts here
when amylase is secreted by salivary glands
Palates and their functions (LT#1) 1. Hard palate pg 299
– Assists the tongue in chewing
2. Soft palate– Closes off the nasopharynx during
swallowing– Uvula projects downward from its
free edge
Uvula plays role in voice – gutteral and click consonants
Function of the tongue (LT#1)
• Gripping and repositioning food during chewing
• Mixing food with saliva and forming the bolus
• Initiation of swallowing, and speech
Pharynx (LT#1)
• Where swallowing occurs• Nasopharynx is covered when soft
palate moves back – so food doesn’t go up your nose
• Glottis is the opening to the larynx @ top of trachea
• Epiglottis covers the trachea during swallowing – so food doesn’t get into lungs
Esophagus (LT#1)
• Connects mouth to stomach• 2 sphincters: one near pharynx =
pharyngoesophageal & one near the stomach = gastroesophageal
• Swallowing pushes bolus (food ball) into the esophagus & peristalsis carries it to stomach (pg 300)
• Peristalsis w/o food = sensation of lump in your throat
Stomach (LT#1)
• Thick walled, J-shaped, upper left quadrant
• Esophagus superior• Duodenum inferior• 3 layers of muscle & rugae (deep
folds)• Gastric glands secrete gastric juice
containing pepsin (digests proteins)
Figure 14.2
Intestines (LT#1)
• Small 3 parts• Duodenum – base of stomach• Jejunum – 1st portion• Ileum – final portion before large
intestine• Suspended by mesentery (pg 302)
Figure 14.11
Small intestine function (LT#1)
• Where majority of digestion occurs• Villi increase surface area for
absorption of nutrients (pg 303)• Digestive hormones control
secretions (Table 15.2 pg 301)
Large intestine or colon (LT#1)pg 307
• Cecum• Vermiform appendix• Ascending colon• Transverse colon• Descending colon• Sigmoid colon• Rectum• Anus
Figure 14.12
Large intestine function (LT#1)
• Absorbs water & electrolytes from chyme
• Prepares indigestible material for excretion from anus (bile gives color, E. coli gives odor)
6 essential activities of the digestive process (LT#1 summary)
• Ingestion• Propulsion• Mechanical digestion• Chemical digestion• Absorption• Defecation
Describe peristalsis & state its function (LT#2) pg 300
Describe the wall of the small intestine & relate its anatomy to nutrient absorption (LT#3) pg 302
Name the hormones produced by the digestive tract that help control digestive secretions (LT#4) pg 301-302
Accessory digestive organs & their contribution to digestion (LT#5)
• Salivary glands• Liver• Gallbladder• Pancreas
Figure 14.5
Salivary glands and their function (LT#5)
• Three pairs of glands – parotid, submandibular, and sublingual
• Cleanses the mouth• Moistens and dissolves food chemicals • Aids in bolus formation• Contains enzymes that break down
starch• Primary function is to begin digestion
by breaking down starch to simple sugars
Figure 14.10
Liver
• Largest gland has 2 lobes• Functional unit is the lobule
(100,000)• “triad” consists of(1) branch of hepatic artery brings
oxygenated blood(2) branch of hepatic portal vein brings
nutrients from intestines(3) bile duct shuttles bile away from
liver
http://www.hopkins-gi.org/GDL_Disease.aspx?CurrentUDV=31&GDL_Cat_ID=BB532D8A-43CB-416C-9FD2-A07AC6426961&GDL_Disease_ID=C8BD9205-E51B-4186-B4E4-B5087B21F9EA
Liver function (page 304)
• Removes toxins from blood brought in from intestines
• Removes & stores fat soluble vitamins A, D, E, & K
• Makes plasma proteins from amino acids (urea is byproduct)
• Pancreas influences liver by insulin & glucagon to maintain blood glucose level
Liver function continued
• Excess glucose stored as glycogen• Produces bile that contains
pigments bilirubin & biliverdin (from breakdown of hemoglobin – rbc pigment)
Gall Bladder
• Pear-shaped muscular organ attached to ventral side of liver
• Stores excess bile produced in liver• Bile enters duodenum to emulsify
fats so they can be further broken down by lipase from the pancreas
Pancreas
• Rests on posterior wall behind stomach
• Cells produce pancreatic juice containing sodium bicarbonate to neutralize pH of chyme
• Digestive enzyme pancreatic amylase for carbs
• Trypsin & chemotrypsin to digest protein aka protease
• Lipase to digest fat