Ch 24 Digestive System Flashcards
Organs include in the digestive system
- Oral cavity(mouth)
- pharynx
- Esophagus
- Stomach
- Small intestine
- Large intestine
Major process of digestive system. write 2
- Ingestion- oral cavity
- Mechanical brakdown - teeth(chewing the food) tongue(facilate swallowing, secretion, taste, smashing food, and degrading food)
Major process of digestive system. write 2
- Propulsion– mainly swallowing, and peristalsis
- Secretions, digestive enzymes, other chemical and hormons.
Major process of digestive system. write 2
- Chemical digestion - bile, HCl and enzymes.
- Absorption - movement of substances from lumen across epithelium, into blood or lymph, may be active or passive.
- Defecation– eliminiation of undugested material and other waste as feces
Name accessory organs
- Teeth
- Tongue
- Salivary glands– secrete lubricating fluid, contain enzymes and break carbohydrates
- Liver – secrete bile, stores nutrients
- Gall bladder — Store bile and concentrate it.
- Pancreas
Pancrease
Endcrine cells – secrete hormones
Exocrine cells– secrete buffers and digestive enzymes.
Functions of Mesentery
- Double layer peritoneum
– Provide route for vessels and nerves to reach digestive viscera
– allow change position and size
– secure organ
– store fat
retroperitoneal oragns
those who have lost their mesentery during development
oral cavity and accessary organ functions
- Sensory analysis of food
- Mechanical digestion
- Lubrication
- Begin chemical digestion (lingual lipase, salivary amylase)
- INitiate swallowing
Functions of tongue
- Mechanical digestion
- manipulation of food
- initiating swallowing
- Sensory analysis with taste buds
- secretions of mucins and lingual lipase
surface involved in chewing
Occlusal surface
Components of teeth
- Enamel- hardest material, avascular and less collagen fiber with excess Ca2+
- Dentin- underlying enamel, shock absorber
- pulp cavity- blood vessels and nerves
- Cement - calcified tissue
Salivary glands
- exocrine glands
- contain serous and mucous cells
Saliva
99.4% water, enzymes, electrolytes, buffers, glycoprotiens, antibodies and wastes.
functions of salivary glands
- cleanse the mouth
- control oral bacteria, protection
- maintain oral pH near neutral
- Dissolve food chemicals for taste
- moisten food to help make bolus
- begin digestion of carbohydrates with salivary amylase
salivary glands names
- parotid gland
- sublingual gland
- submandibular gland
Digestive tract layers
4 layers
- Mucosa
- submucosa layer
- Muscular layer (muscularis externa)
- serosa or adventitia
Mucosa
–Epithelium- stratified squamous or simple columnar
–Lamina Propria -areolar tissue, lymphoid tissue and glands
– muscularis mucosae - smooth muscles
Submucosa
– Areolar connective tissue, blood and lymphatic vessels nerves that serve the wall of GI tract
–Additional lymphoid tissue and glands
Muscular layer (muscularis externa)
–Circular layer of smooth muscle
– Longitudinal layer of smooth muscle
–Stomach only also have oblique layer of smooth muscle
Serosa Or adventitia
serosa = visceral peritoneum
Adventitia = dense connective tissue attachment for surrounding structures,
– Retroperitoneal organs often have anterior serosa and posterior adventitia
Serosa Or adventitia
serosa = visceral peritoneum
Adventitia = dense connective tissue attachment for surrounding structures,
– Retroperitoneal organs often have anterior serosa and posterior adventitia
where do nerve plexuses be found
Intrinsic nerve plexuses
Found between submucosal and muscular layer
–Myenteric NP
– Submucosal NP
Structure of esophagus
– Longitudinal muscle helps with expansion
– submucosa contain mucous glands for bolus lubrication
– Peristalsis move bolus down
At the stomach-esophagus joint what mucous protect from?
It protects walls from the stomach acid
What key functions of stomach
– Mechanical digestion and propulsion
– Chemical digestion-. protein digestion, HCl, and pepsin help turn bolus into chyme
–HCl kill bacteria
temporary storage of food.
Regions of Stomach
- Cardia= near heart and a lot of mucous glands
- Fundus= dome-like upper part, above attachment point.
- Body (middle )
- pyloric part -strong peristalsis waves
Mucosa of stomach
–Gastric pits
– mucous epithelium
– lamina propria
– muscularis mucosae
Muscular layer of stomach
– Oblique muscle
– circular muscle
– Longitudinal muscle
stomach mucosal barrier
–Largely mucous secreting cell
Mucous rich in alkaline bicarbonate
– tight junctions
– high epithelial regeneration 3-6 days
Cells of gastric glands
- chief cells
- G cells
- Parietal cells
Chief cells
–rectangle shaped cells
– secrete pesinoge
–pepsinogen is precursor to pepsin
Parietal cells
–rectangle shaped
– secete HCl
– secrete intrinsic factor- required for B12 absorption
G cells
–two cells at the end of tube
– secrete gastrin hormon
– gastrin enhance gastric activity
Duodenum
–protect against acidic pH of entring chyme
– mix in secretions with pancreatic juice and bile
–fewer circular folds
– smaller villi
Jejunum
– prominent circular folds and villi
– most digestion and absorption
ileum
–major absorption of B12 and bile
– Peyer’s patches connect to the large intestine
biles
–aids in digestion and absorption of fats
– mainly water
– bilirubin ions and cholestrol lipds
– bile salts emulsify lipids
–bile salts get recycle
Functions of liver
– bile production for digestion
– metabolic reactions
– hematological (recycleing of blood) secreting plasma protein
what happen to blood come from hepatic portal vein
– modify its composition
– filter for toxin and drugs
– modify nutrient composition
lobes of liver
– left
– right
– Caudate
– quadrate
name pancreatic enzymes
– Alpha amylase
– Lipases
– proteases
– nucleases
Functions of large intestine
–Re or absorption == Water, organic waste, less than 10% nutrients,
toxins and vitamins and bile salts
– compact the intestinal content into feces form
– storage of fecal before defacation
what are contribution of microbes
–synthesis vitamin K and B comples
what are contribution of microbes
fermentation== break down of any protein enter here and undigestible carbhydrates
this produces gas flatus production
what are contribution of microbes
it alters the characteristics of feces
– Beneficial bacteria outcompete and suppress harmful bacteria
histology of large intestine
– no circular fold
- no villi
– no brush borders
– thick mucosa== abundant crypts and goblet cells
– mucous provide lubrication and protection against bacteria
Rectum
– stratified squamous epithelium
– anal colum
–anal canal
– internal anal sphincter
– external anal sphincter
Defecatioon
Streching walls of rectal wall
relax intrisic internal anal sphincter
relax voluntarily external anal sphister
