GI 1 Flashcards
1
Q
What are the functions of the alimentary canal?
A
- ingestion: bringing food in
- secretions: lots of secretions along whole length of tube (saliva, enzymes, bile, gastric juices)
- mixing and propulsion: propulsion moves food from mouth towards bottom end, mixing through coordinated contractions of muscles of GI wall which can segment the tube
- digestion: breaking food down by mechanical fashion or chemical fashion (acids and enzymes produced by various organs)
- absorption: taking nutrients that have been broken down and bringing them into bloodstream
- defecation: things that can not be absorbed are excreted
2
Q
What is the function of the gums, teeth, tongue, lips, cheek, hard and soft palate, and uvula in terms of digestion?
A
- gums and cheek keep teeth in place and work to get food into working spaces of teeth to break down food mechanically
- lips close off the oral cavity as you are chewing so food doesn’t fall out
- superior and inferior labial frenulum help to restrict movement of lips
- hard palate part of maxilla covered by mucous membrane
- soft palate contains skeletal muscle to close off nasopharynx to prevent food from entering
- uvula has large density of irritant receptors to get reflex response of emesis (vomiting)
- lingual frenulum restricts backward movement of the tongue
3
Q
Where is the opening to the duct of the submandibular gland located?
A
- under the tongue
- secretes saliva
- stimulate anterior 1/3 of tongue and you will observe saliva under tongue
4
Q
What are the primary tastes?
A
-sweet, bitter, salty, sour, and umami
5
Q
What are the types of papillae?
A
- vallate papillae: 12 each containing 100-300 taste buds
- fungiform papillae: scattered over tongue each containing 5 taste buds
- foliate papillae: in the lateral margins of the tongue; degenerate in childhood
- filiform papillae: tactile sensations and friction (no taste buds)
- approximately 10 000 taste buds
6
Q
What are taste buds made of?
A
- gustatory receptor cells
- specialized epithelial cells
- detect chemical stimuli and release a neurotransmitter signal onto the neuron
- cells are constantly being regenerated
- neuron is deep in the tongue so it is not exposed to the harsh food environment
7
Q
What cranial nerves are involved in gustation?
A
- facial nerve (anterior 2/3)
- glossopharyngeal (posterior 1/3)
- vagus (throat and epiglottis)
- tactile sensations are somatic and travels through mandibular branch of CN5 (trigeminal)
- taste ends up in parietal lobe
8
Q
How does olfaction occur?
A
- specialized epithelial cells that detect chemicals that have become dissolved within mucus lining nasal cavity (superior part on cribriform plate)
- put NTs on cranial nerve 1 and that sensation of smell goes up those neurons to primary olfactory cortex in insular cortex
- does not synapse in the thalamus (lose sense of smell over time with a particular smell because of receptor desensitization, not because thalamus is filtering it out
9
Q
What are the types of teeth and dentitions?
A
- incisors for cutting (4)
- canines for tearing (2)
- premolars for crushing (4)
- molars for grinding (6)
- 32 teeth in total if you have all of them
- deciduous dentition (baby teeth) and permanent dentition
10
Q
A
- enamel is hardest substance in body
- teeth are 95% calcium salts (more than bones)
- dentin is less calcified version of enamel
- pulp in pulp cavity is analagous to bone marrow- supplied by blood vessels and nerves (CN5)
- periodontal ligaments hold teeth in place made up of collagen
- vitamin C needed to make strong collagen so over time, if you don’t have adequate vitamin C in your diet the periodontal ligaments will become weak and teeth will fall out (scurvy)
11
Q
What is mastication?
A
- effort between teeth, tongue, and cheek
- small working space in mouth for grinding down food between teeth
- tongue and cheek put food up there to do mastication
- requires saliva to lubricate it which has enzymes to start chemical digestion
- parotid gland sits just in front of ear, duct releases about level of 2nd molar
- submandibular gland under mandible
- sublingual gland which has several ducts along base of tongue
- partly a reflex action from pattern generators and also have voluntary control
12
Q
A
- both sets of longitudinal muscles contract at the same time and cause shortening of the tongue
- if you were just to contract the upper layer, tongue curls upwards
- transverse muscles contract to make tongue thinner
- if you just contract the upper layer you can make a slide out of it
- vertical muscle contraction flattens tongue out useful for moving tongue around
- all intrinsic muscles of tongue are innervated by CN12
13
Q
A
- styloglossus attached to styloid process and tongue, when contracted tongue elevates in the oral cavity useful when trying to swallow
- hyoglossus attached to hyoid bone and tongue
- genioglossus attached from base of tongue in back to chin, when it contracts it brings it forward in the oral cavity
14
Q
A
- have action on jaw to help close mouth
- temporalis lies over the temporal bone and sends its tendon over the zygomatic arch
- if you clench your jaw, can feel this muscle above the ear
- masseter is main muscle of mastication arising from maxilla down to mandible
- both controlled by CN5
15
Q
A
- innervated by facial nerve
- buccinator muscle contracts to keep food up against cheek when chewing (this one gets sore when blowing up a balloon)
- orbicularis oris acts as sphincter around the lips to keep food in mouth
16
Q
Describe the blood supply to the muscles of mastication
A
- comes from external carotid
- facial artery goes under mandible to supply lower jaw
- maxillary artery supplies structures of upper jaw/nasal cavity
- superficial temporal artery supplies temporalis muscle
- veins are the same names
21
Q
What are the kinks and hiatus of the esophagus?
A
- as esophagus passes behind trachea it will have a kink
- kink at left atrium
- hiatus through diaphragm
22
Q
Describe the histology of the esophagus
A
- mucosa: nonkeratinized stratified squamous epithelium
- lamina propria: connective tissue that glues endothelium to lower structures and where epithelium gets blood vessels from
- muscularis mucosae: smooth muscle which puts the overlying epithelium into folds
- submucosa
- muscularis: inner circular layer and outer longitudinal layer, forces bolus of food (circular layer contracts to push it down, longitudial contracts in front of bolus to ease its movement)
- adventitia (connective tissue anchoring it to neck)
24
Q
What occurs during late deglutition?
A
- lower esophageal (gastroesophageal) sphincter keeps acidic content of stomach out of the esophagus
- as food bolus approaches lower esophageal sphincter it momentarily relaxes to allow bolus through
- stomach produces a sticky mucus with a lot of bicarb but the esophagus has no protective mucus layer
