Exam 3 CH 24 Flashcards
Understand the functions of the digestive system and know where each of the functions is achieved through the system
- Ingestion: eating
- Mastication: Chewing
- Propulsion: Move stuff from one end of the digestive tract to the other.
-Swallowing (deglutition)- moves liquids or a soft
mass of food called BOLUS (esophagus to
intestines)
-Peristalsis- Movement of food from one end of
the digestive tract to the other.
-Mass Movements- Contractions that move
the material in the distal parts of the large
intestine to the anus. “Big push” - Mixing: Move food back and forward to allow it to get mixed with digestive secretions to break it into smaller pieces.
- Secretion
-Mucus- Lubricates the food and the lining of the
tract.
-Water- Liquifies the food for easy digestion and
absorption
-Enzymes- Secreted by the oral cavity, stomach,
small intestine, and pancreas break down large
food molecules into smaller molecules that can
be absorbed by the intestinal wall. - Digestion: The breakdown of large organic molecules into components: Carbohydrates into monosaccharides, proteins into amino acids, triglycerides into fatty acids and glycerol.
-Mechanical: Mastication and mixing food,
Smaller pieces to increase surface area.
-Chemical: Digestive enzymes secreted along
the digestive - Absorption: Movement of molecules out of the digestive tract into the blood or LS.
- Elimination: Removing waste products from the body
- Defication- Feces
Know the histology of the digestive tract and the significance of each layer.
Mucosa
-Innermost tunic
-Consisted of 3 layers
-Inner MUCOUS EPITHELIUM
-Stratified squamous in the mouth, oropharynx
esophagus and anal canal
-Simple columnar epithelium in the rest of the
tract.
-LAMINA PROPRIA
- Loose connective tissue
-Outer MUSCULARIS MOCOSAE
-Folds to increase surface area.
Submucosa
- Under mucosa tunic
- Thick connective tissue
- Tunic consists of nerves, blood vessels, lymphatic vessels, and small glands
Muscluaris
- Fat layer? Helps with enteric nervous system (ENS)
Serosa or Adventitia
-Serosa is called visceral peritoneum
Compare and contrast the nervous and chemical regulation of the digestive system
Nervous Regualtion
-Enteric nervous system
-Local
-Peristalsis
-Coordination with the CNS
- May initiate reflexes because of sight, smell, or taste
of food (Salivate/ Stomach grumble)
-Parasympathetic primarily
-Sympathetic (stressed out)
-Inhibits muscle contraction and secretion
-Decrease of blood flow to the digestive tract
Chemical Regulation
- Production of hormones
- Gastrin, secretin (tells us we are hungry)
- Production of paracrine chemicals
- Helps local reflexes
Understand the function of the peritoneum and how it is arranged
-Serous membrane
-Visceral peritoneum- Covers organs
-Parietal peritoneum- Covers the interior surface of
the abdominal cavity
-Retroperitoneal (Behind peritoneum) (Abdominal organs with no mesenteries)
-Duodenum, pancreas, ascending colon, descending
colon, rectum, kidneys, adrenal glands, and urinary
bladder
-Mesenteries (folds over large/small) (Serous membranes attached to abdominal organs)
- Mesentary proper: mesentery dealing with the small
intestines.
-Lesser omentum: Connecting the lesser curvature
of the stomach and the proximal end of the
duodenum to the liver and the diaphragm.
-Greater omentum: A fold from the greater curvature
and the transverse colon
-Ligaments
-Coronary: Attaches liver to the diaphragm
- Falciform: Attaches liver to anterior of the abdominal
wall
Understand the importance of the mouth and its associated structure
Oral Cavity
-Tongue
-Intrinsic muscles: Within tongue itself. Change the
shape
of tongue flattening/elevating
-Extrinsic: Outside the tongue but attached to it.
Protrude/retract and move it side to side
-Papillae- Tastebuds
-Functions: Movement of food, speech, and swallowing
Teeth (accessory)
-Mastication
-Reflex centered in the medulla oblongata
(Controls chewing)
-Two sets
-Deciduous (baby/milk teeth)
-Permanent
-Types
-Incisors and Canines: Ripping and Tearing
-Premolars and Molars: Grinding
Understand what is involved in mastication
-Mastication
-Reflex centered in the medulla oblongata
(Controls chewing)
-Make food into smaller pieces in order to increase surface area for digestive enzymes
Know the composition, production, and function of salvia
Salivary Glands
- Three pairs
-Parotid (largest) Anterior to ears
-Serous gland
-Mostly water
-Submandibular
-Primarily water
-Sublingual (smallest)
-Primarily mucous
Parasympathetic Control
-Saliva
-Combination of serous and mucous secretions
-Prevent bacterial infection
-Lubrication
- Contains salivary amylase (breakdown
carbohydrates)
-Bolus formation: What chewed food becomesUnderstand deglutition and peristalsis
Deglutition (swallowing)
- Three Phases
-Voluntary; Bolus formed in the mouth and pushed
toward oropharynx
-Pharyngeal: Reflex
-Swallowing center is in the medulla oblongata
-Pharynx to esophagus
-Esophageal: Reflex
-Stretching of the esophagus causes enteric NS
to initiate peristalsis of muscles in the muscles
Peristalsis
- A wave of smooth muscle relaxation moves ahead of the bolus, allowing the digestive tract to expand.
- A wave of contraction of the smooth muscle behind the bolus propels it through the digestive tract
Know the histology of the stomach; make sure to you know the different types of cells and what they are responsible for producing.
Layers
-Serosa or visceral peritoneum
-Outmost tunic of stomach
-Outer simple squamous epithelium and inner
connective tissue.
-Muscularis
-Outer longitudinal:
-Middle circular layer
-Inner oblique layer: Generate stomach contractions
for food breakdown
-Submucosa and Mucosa: Have large folds called rugae. Mucous to create a layer between tissue and helps with pH
Gastric pits
-Cells of gastric pits
-Surface mucous: Protect stomach from acids and
digestive enzymes
-Mucous neck
-Parietal (hydrochloric acid)
- Chief (pepsinogen)
-Endocrine cells
-Enterochromaffin-like cells: histamine that stimulate
acid secretion
-Gastric-containing cells: Secrete gastrin
-Somatostatin-containing cells: Secrete somatostatin
that inhibits gastrin and insulin secretion
Know the secretion of the stomach and their functions, also, understand the regulation of stomach secretion
Chyme
- Mucus
- Alkaline
- Protects from acidic chyme and enzyme pepsin
- Irritation of stomach mucosa causes greater mucus
