Digestive System Review

1. Digestive System Review Chapter 15

2. Which organs/structures constitute the digestive system? • Mouth • Esophagus • Pharynx • Stomach • Small & large intestines • Rectum & anus • Accessory organs include the salivary glands, liver, gallbladder, and pancreas

3. Describe the wall of the alimentary canal. • Mucosa – innermost layer; contains lumen (lines tube) • Submucosa – middle layer; contains blood vessels, nerves, & glands • Muscular layer – middle layer; produces tube movements • Serosa – outermost layer; secretes serous fluid

4. Name two types of movements that occur in the alimentary canal. • 1. Mixing – rhythmic contractions • 2. Propelling – wave-like contractions (peristalsis)

5. How does the tongue and palate function as part of the digestive system? • The tongue mixes food particles with saliva and moves food towards the pharynx. • The palates (hard and soft) form the roof of the oral cavity and help close off the nasal cavity during swallowing (soft palate).

6. Describe the structure of a tooth. • Each tooth consists of four layers: 1. Pulp – nerves & blood vessels 2. Dentin – hard inside 3. Enamel – tough, outer coating 4. Cementum – roots ONLY!

7. What are the different types of teeth and how is each used? • Four different types of teeth: 1. Incisors – big, flat; used for biting off food pieces 2. Canines – sharp, pointy; used for tearing or cutting 3. Bicuspids – two-pointed; used for grinding 4. Molars – flat, square; used for grinding

8. Describe the regions of the pharynx. • Consists of three main parts: 1. Nasopharynx – nasal cavity 2. Oropharynx – oral cavity 3. Laryngopharynx – esophagus

9. List the major events that occur during swallowing. • Stage One – food is chewed and mixed with saliva (bolus) • Stage Two – food triggers sensory receptors with begin the swallowing reflex (epiglottis closes, breathing momentarily stops) • Stage Three – peristalsis transports food to the stomach through the esophagus

10. What is the function of the esophagus? • Tube or food passageway from the pharynx to the stomach. • Lubricates food as it travels down the tube to the stomach.

11. What is the importance of each type of stomach secretion? • Gastric glands secrete gastric juice consisting of: • hydrochloric acid (forms acidic environment) • pepsin (digests proteins) • mucous (protective lining) • intrinsic factor (vitamin B12 absorption)

12. List the enzymes and their functions found in pancreatic juice. • Pancreatic juice contains enzymes that digest: • Carbs (pancreatic amylase) • Fats (pancreatic lipase) • Proteins (trypsin, chymotrypsin, carboxypeptidase) • Nucleic acids (nucleases)

13. What is the structure and function of the liver? • Structure – divided into two lobes which contain hepatic lobules and sinusoids • Function – filters toxins out of the blood; metabolism; secretes bile

14. Describe the structure and function of the small intestine. • Structure – long tube containing villi; has three parts: duodenum, jejunum, & ileum • Function – main area for absorption of nutrients

15. Describe the structure and function of the large intestine. • Structure – large diameter tube; has four parts: cecum, colon (4 parts), rectum, and anus • Function – main area for absorption of water and electrolytes; forms and stores feces

16. What are the similarities and differences between the large and small intestines? • Large IntestineSmall Intestine Large diameter Small diameter Absorbs water Absorbs nutrients No villi Contains villi Shorter Very long Bacteria Enzymes