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BIOL 105
Lecture Outline Chapter 14 ʹDigestive System & Nutrition Read Chapter 14 in your textbook (pp. 468-‐516) Complete Chapter Review questions (pp. 514-‐ϱϭϲͿη͛Ɛ͗ϭ -‐4, 6-‐8, 10, 12, 14-‐27, 29-‐ Digestive System Digestion: ____________________ and ____________________ breakdown of foods Breakdown allows for ____________________ of nutrient molecules The digestive system consists of:
Tube that runs from the mouth to the anus
Salivary glands, liver, gallbladder, and pancreas Food does NOT travel through the accessory organs! Alimentary Canal Tube is ~________ in length Runs through the ____________________ and ______________________________ cavities Outermost layer = ____________________ ( serous layer; composed of visceral peritoneum ) Secretes ____________________ o Protects underlying tissue o Lubrication of the tube prevents friction with organs of the abdominal cavity Middle layer = ____________________ ( two layers of smooth muscle ) Moves food through the tube o Contraction of circular fibers ʹ decreases diameter o Contraction of longitudinal fibers ʹ shortens tube Innermost layer = ____________________ ( mucous layer ) Layer of secretion and absorption o Secretes ____________________: helps to slide food through the tube
In some regions, the mucosa is folded o ____________________: tiny projections of the mucosa; increase surface area for absorption ____________________ ( external to the mucosa ) contains glands, blood vessels, lymphatic vessels, and nerves Movements of the Tube ____________________ movements Smooth muscle contracts rhythmically in small sections of the tube ____________________ movements ____________________: wavelike motion Waves of contraction and relaxation o Contraction pushes food through the tube; relaxation allows food to move into the next segment of the tube Mouth Receives ____________________ Both ____________________ and ____________________ digestion occur in the mouth ____________________: mechanical breakdown of food ( chewing ) _______________ secreted in the saliva initiate chemical digestion Cheeks and Lips ____________________ form the lateral walls of the mouth Composed of: skin, muscle, fat, and epithelium o Do you remember the muscles that are located within the cheeks that are associated with chewing and facial expression? ____________________ surround the mouth opening Composed of skeletal muscle Contain sensory receptors ʹ detect food temperature and texture Tongue Composed of ____________________ muscle tissue
____________________ (4)
ůƐŽƌĞĨĞƌƌĞĚƚŽĂƐ͞ cuspids ͟ Grasp and tear food ____________________ (8) ůƐŽƌĞĨĞƌƌĞĚƚŽĂƐ͞ bicuspids ͟ Grind food particles ____________________ (12) Grind food particles Structure of a tooth: ____________________: projects beyond the gingiva (gums) Enamel covers the crown ____________________: anchored to the jaw bone ____________________ ( bulk of the tooth ) surrounds the pulp cavity The pulp cavity in the root of the tooth consists of nerve fibers, blood vessels, andconnective tissue
The ________________________________________ holds the tooth in its socket Dental caries (cavities) occur when bacteria in the oral cavity breakdown sugar and Salivary Glands Secrete ____________________ Begins chemical digestion of carbohydrates ( salivary amylase ) Moistens, dissolves, and binds food particles together Allows the chemical sensation of taste Helps cleanse the mouth and teeth ______________________________ stimulation triggers a large production of saliva at the sight or smell of food Contain two types of secretory cells: ____________________ cells: watery fluid filled with the enzyme amylase ____________________ cells: produce lubricating and binding mucous Three pairs of major salivary glands: ____________________ glands Largest of the salivary glands
Lie anterior to the ears ____________________ glands Located in the floor of the mouth; inside surface of the lower jaw ____________________ glands Located in the floor of the mouth; inferior to the tongue Pharynx Passageway between the nasal/oral cavities and the ____________________ ( respiratory ) and/or ____________________ ( digestive )
NO DIGESTION OCCURS IN THE PHARYNX!! Divided into three parts: _________________________ (top) o Passageway for air during breathing
_________________________ (middle) o Passageway for both air and food _________________________ (bottom) o Passageway to the esophagus Esophagus Passageway for food from the ____________________ to the ____________________ Posterior to the ____________________ and anterior to the ____________________ Passes through the ______________________________ and penetrates the ____________________ through the esophageal hiatus NO DIGESTION OCCURS IN THE ESOPHAGUS!! ____________________ gland secretions moisten and lubricate the tube The ________________________________________ sphincter ( cardiac sphincter ) prevents regurgitation of stomach contents into the esophagus
____________________
Main portion of the stomach; lies between the fundic and pyloric regions
Approaching the small intestine ʹ pyloric sphincter located between the stomach and small intestine Gastric Secretions Gastric glands have 3 types of secretory cells: ____________________ cells Secrete mucous ʹ prevents the stomach from digesting itself ____________________ cells Secretes hydrochloric acid (HCL) Secrete intrinsic factor ʹ stimulates absorption of vitamin B 12 in the small intestine ____________________ cells Secrete pepsinogen (an inactive enzyme) o In the presence of HCL pepsinogen is activated to pepsin o Pepsin initiates breakdown of dietary protein Regulation of gastric secretions: Parasympathetic fibers stimulate the release of ____________________ from nerve endings Parasympathetic impulses also stimulate the production of the hormone __________________ Both ACh ( acetylcholine ) and gastrin increase secretory activity of the gastric glands As food moves into the small intestine, sympathetic nerve impulses inhibit gastric secretions The hormone ______________________________ (CCK) also decreases gastric secretions The small intestine receives ____________________ (thick, soupy liquid) from the stomach Through the ____________________ sphincter As chyme enters the small intestine, the accessory organs add their secretions The rate at which the stomach empties depends on the fluidity of chyme and the type of food present ____________________ move faster than ____________________
____________________________ moves faster than __________________ and
Pancreas Is both an exocrine and endocrine gland Exocrine ʹ produces digestive enzymes Do you remember the endocrine functions of the pancreas? Extends ___________________________________ across the abdominal wall Closely associated with the small intestine Located posterior and inferior to the ____________________ The pancreatic duct extends the length of the pancreas Connects with the _________________________ ( small intestine) at the same place as the bile duct (from the liver and gallbladder) Pancreatic juice contains many enzymes:
Digests carbohydrates
Digests lipids (along with bile secretions from the liver/gallbladder)
Breakdown nucleic acids into nucleotides Trypsin, chymotrypsin, and carboxypeptidase Digest ____________________ Regulation of pancreatic secretions: Parasympathetic impulses stimulate the pancreas to ____________________ digestive enzymes As chyme enters the duodenum (small intestine), the membrane releases the hormone
Stimulates the secretion of bicarbonate ions ʹ neutralizes the acidity of chyme
Stores ____________________ Secretions travel into the duodenum via the common bile duct o CCK stimulates the gallbladder to contract Æ releasing bile
Bile salts emulsify _______________ globules into smaller droplets o Increases surface area of the fat molecules Æ lipases can then digest fat molecules Bile salts also aid in the ____________________ of fatty acids, cholesterol, and vitamins Small Intestine Extends from the ____________________ sphincter to the _____________________________ Roughly ________ (18ft.) in length Receives secretions from the ____________________ and ____________________ Via the pancreatic and common bile ducts Completes digestion of the ____________________ ____________________ nutrients Transports residues to the ______________________________ Parts of the small intestine: ____________________ (first 25cm) ____________________ (2 nd^ segment) ____________________ (3 rd^ segment) The small intestine is suspended from the posterior abdominal wall by the _________________ (fold of peritoneum) Structure of the small intestine: Inner wall is covered with tiny, fingerlike ____________________ Increase the surface area of the intestinal lining Æ aiding absorption of nutrients Villi structure: Contains a core of connective tissue housing blood capillaries, ____________________ ( lymphatic capillaries ), and nerve fibers
Blood capillaries and lacteals carry away ______________________________________ Nerve impulses stimulate/inhibit ________________________________________ Secretion and absorption in the small intestine: Cells of the intestinal mucosa have enzymes embedded in their membranes
Split peptides into amino acids Amino acids are absorbed into the villi and carried away by the blood ____________________, ____________________, and ____________________ Split disaccharides into simple sugars Sugars are absorbed into the villi and carried away by the blood
Splits fats into fatty acids and glycerol Fatty acids are absorbed by villi cells, reconstructed, and eventually carried away by the blood Movements of the small intestine: _________________________: mixing movements Ringlike contractions move chyme back and forth o Slows the movement of chyme through the small intestine ____________________ waves also moves chyme through the small intestine Chyme takes ______________ hours to travel the length of the small intestine Large Intestine Extends from the ____________________ to the ____________________ Larger in ____________________, but shorter in ____________________ than the small intestine Absorbs ____________________ and ____________________ from chyme; forms and stores feces Large intestine does not digest or absorb nutrients Feces are composed of undigested material, water, electrolytes, mucous and bacteria Parts of the large intestine:
Located at the beginning of the large intestine
