digestive system part 2

9. Mouth and tongue anatomy.

10. Where are lingual glands located and what enzyme do they secrete? Mouth, lingual lipase Is the secretion active or inactive when first secreted? Inactive Where is it activated? HCL in stomach activates it

Lingual glands-secrete lingual lipase that is used to catabolize triglycerides in stomach

a. works best at a low acidic pH, which is why it works in stomach

b. Released in mouth BUT HCl in stomach activates it!

11. What is the lingual frenulum?

Lingual frenulum- fold of mucous membrane in midline of undersurface of tongue

Attached to floor of mouth and aids in limiting movements of tongue, (stabilizing the tongue)

12. What are the 2 pharyngeal arches?

Palatoglossal arch(anterior) and palatopharyngeal arch(posterior)

13. What are the types of tongue papillae? (4)

Vallate papillae, Fungiform papillae, & Foliate papillae (all these have tastebuds)

Filiform (no tastebuds)

14. Anatomy of teeth. Define periodontal ligament, gingivae, dentin, enamel, hydroxyapatite, cementum, and pulp cavity.

Periodontal ligament- a dense fibrous connective tissue that anchors the teeth to the socket walls

Gingivae- gum

Dental pulp- is the part in the center of a tooth made up of living connective tissue and cells called odontoblasts (produce dentin)

Dentin- forms majority of tooth and consists of calcified CT

Enamel- covers dentin of crown and consists of calcium phosphate and calcium carbonate

Hydroxyapatite -primary mineral in dentin and enamel (calcium phosphate). Hardest substance in body and protects teeth against damage and acid

Cementum - which attaches root to periodontal ligament. Gives tooth basic shape

15. Name the 3 divisions of the pharynx.

Nasopharynx, oropharynx, laryngopharynx

16. What events happen during deglutition? Define: Voluntary, pharyngeal, and esophageal stages. Hint: What happens to the soft palate, larynx, epiglottis, upper esophageal sphincter?

Deglutition- is the act of swallowing food

Deglutition consists of 3 phases:

a. voluntary state (voluntary) - act of the tongue forcing the bolus to the back of the oral cavity and into the oropharynx

b. Pharyngeal stage(involuntary)- begins as the bolus passes into the oropharynx

receptors send impulses to the deglutition center in the medulla and pons

Returning impulses cause the soft palate to move superiorly and posteriorly to close the nasopharynx

Epiglottis moves slightly inferiorly to close the glottis

c. esophageal stage (involuntary) of swallowing begins once the bolus enters the esophagus

Peristalsis - progression of coordinated contractions and relaxations of the circular and longitudinal layers of the muscularis

push the bolus onward

17. What are the functions of the stomach, including chyme, HCl, pepsin, gastric lipase, gastrin?

Mixes saliva, food, and gastric juice to form chyme

Serves as reservoir for food before release into small intestine

Secretes gastric juice, which contains HCL (kills bacteria and denatures proteins)

a. Secretes pepsin (pepsinogen precursor) (begins digestion of proteins)

b. Secretes gastric lipase (aids digestion of triglycerides)

Secretes gastrin into blood

c. Released in pyloric antrum, duodenum, and pancreas

Gastrin - Peptide hormone that stimulates secretion of HCl by parietal cells

pepsin (begins digestion of proteins)

gastric lipase (aids digestion of triglycerides)

18. Know different structures of the stomach (pyloric antrum, cardiac, body, pyloric antrum, pyloric canal, pylorus, pyloric sphincter, lesser and greater curvature).

cardia-surrounds opening of esophagus into stomach

Body-inferior to fundus and is large central portion of stomach

Pyloric part-divisible into 3 regions

Pyloric antrum-connects to body

Pyloric sphincter-smooth muscle

Pylorus communicates with duodenum via this sphincter

Lesser curvature-concave medial border of stomach

Greater curvature-convex lateral border

Pyloric canal-leads to third region called pylorus which in turns connects to duodenum

19. What are the functions of mucous neck cells, parietal cells, chief cells, G cells?

Mucous neck cells- secretes mucus

Parietal cells- produce intrinsic factor (vit b12 to produce RBC)and HCL (HCl activate pepsinogen into pepsin)

Chief cells – produce pepsinogen and gastric lipase

G cells- secrete gastrin

20. Histology of stomach. Know the layers and what they are composed of.

1. Submucosa-composed of areolar CT

2. Muscularis has three layers of smooth muscle: longitudinal, circular, and an inner oblique layer

a. Muscularis has 3 layers of smooth muscle rather than 2 found in esophagus and intestines

3. Serosa is a part of the visceral peritoneum

b. Composed of simple squamous epithelium and areolar CT

21. What is propulsion and retropulsion? Gastric emptying?

Propulsion- Each peristaltic wave moves gastric contents from body down into antrum

Retropulsion (propulsion repeated) - Pyloric sphincter remains closed at this point (food too large to pass) so food is pushed back into body

Gastric emptying - Once chyme is small enough it passes through pyloric sphincter