Lecture 16: Digestive system two Flashcards
what is the mechanical digestion for food called?
Mastication
whats the function of saliva?
lubricate food
amylase”digests starch and glycogen
dissolves molecules for taste
how is food propelled to the pharynx?
propelled by the tongue
how is the enamel of teeth made?
by ameloblasts.
how is dentin for teeth made?
odontoblasts.
what does the Pulp cavity contain?
blood vessels and nerve endings
is the tongue a skeletal muscle?
yes
whats the scientific term for taste buds?
papillae
what glands does the tongue have?
lingual glands
what another term for pharynx ?
throat
what is the pharynx used for?
air fluid and food
how’s does food enter the pharynx ?
via the esophagus
what is the esophagus?
Muscular tube from pharynx to stomach
How many sphincters does the oesophagus have?
two
Upper esophageal sphincter
Lower esophageal sphincter
where is the Upper esophageal sphincter
located?
Between pharynx and esophagus
where is the lower esophageal sphincter
located?
Between esophagus and stomach
what does the lower esophageal sphincter do?
Prevents the acidic content of the stomach from entering the esophagus
what are the three stages of swallowing?
- Oral preparatory phase
- Pharyngeal phase
- Oesophageal phase
what is the Oral preparatory phase?
Chewing, saliva, food formed into bolus by tongue, soft palate closes to prevent nasal aspiration (voluntary control)
what is the Pharyngeal phase?
bolus moved by peristalsis (involuntary), epiglottis blocks trachea
what is the Oesophageal phase?
peristalsis waves move bolus, lower esophageal sphincter relaxes to allow bolus into stomach
what are the three regions of the stomach?
fundus, body, antrum
what is the funds of the stomach?
Thin wall that easily expands
what is the body of the stomach?
Gastric mucosa folds in Rugae
what is the antrum of the stomach?
Thickest muscle, produces contractions responsible for gastric mixing and emptying
what does the Pyloric sphincter do?
regulates the passage of chyme to duodenum
what are the functions of the stomach?
store food mechanical digestion chemical digestion secretion of muscus Passage of chyme to small intestine Secretion of intrinsic factor
How much food can the stomach hold?
4L
what secretes gastric juice?
stomach
what are the components of gastric juice?
- Mucus
- HCl
- Pepsinogen
- Intrinsic factor
- Gastric lipase
Ho long and wide is the small intestine?
4m long and 2.5cm diameter
what are the sub divisions of the SI?
duodenum, jejunum, ileum
where is the duodenum located?
it is attached to the stomach, and curves around the head of the pancreas
where is the jejunum located?
Attached anteriorly to the duodenum
where is the ileum located?
Extends from jejunum to large intestine
Meets the large intestine at the ileocecal valve
whats the functions of the small intestines?
motility
secretion of alkaline msucus
major site of digestion
major site of absorption
what is motility?
Segmentation and Peristalsis
what increases the SA of the wall of the small intestine?
Circular folds, villi, microvilli
what are brush border enzymes?
Disaccharidases (maltase, sucrase, lactase)
Peptidases (Enteropeptidase- activates trypsinogen)
Phosphatases
what are the sections of the large intestines?
Cecum Appendix Colon rectum anal canal
whats the size of the large intestine?
1.3m long, 6.3cm diameter
what does the colon empty into?
rectum
where is faces excreted from?
anus
what type of muscle does the internal anal sphincter have?
smooth msucle
what type of muscle does the external anal sphincter have?
skeletal muscle
whats the function of the large intestine?
Water absorption Electrolyte absorption waves and mass movements Mucus secretion Synthesis of B12 and K Reservoir of undigested material prior to elimination
what does intestinal bacteria do in the large intestine?
perform fermentation reactions that produce short chain fatty acids and flatus.
