Physiology

Question 1

What are the four steps of oral motor function?

Answer 1

(Prehension, chewing, initiation of swallowing, and deglutition aka swallowing)

Question 2

What organ is primarily responsible for food prehension in dogs and cats?

Answer 2

(Teeth)

Question 3

What organ is primarily responsible for food prehension in horses?

Answer 3

(Lips)

Question 4

What organ is primarily responsible for food prehension in ruminants?

Answer 4

(Tongue)

Question 5

What organ is used for water ingestion in dogs and cats?

Answer 5

(Tongue)

Question 6

What organ is used for water ingestion in horses, ruminants, and pigs?

Answer 6

(Lips)

Question 7

What does mucin, which is contained in saliva, facilitate?

Answer 7

(Mucin is a slippery protein → facilitates swallowing)

Question 8

(T/F) Most animal species we work with have limited to absent salivary amylase in their saliva.

Answer 8

(T)

Question 9

What extra substance does ruminant saliva contain which is essential for microbial digestion?

Answer 9

(Ruminal buffers)

Question 10

What type of epithelium is located within the esophagus that allows for wear and tear with each swallow?

Answer 10

(Stratified squamous epithelium)

Question 11

Which two species have skeletal muscle in their upper ⅔ of the esophagus and smooth muscle in the distal 1/3 of the esophagus?

Answer 11

(Cats and horses)

Question 12

What are the two purposes of the upper esophageal sphincter?

Answer 12

(Prevents air entry into esophagus during breathing and prevents reflux into pharynx during swallowing)

Question 13

Which of the esophageal sphincters (upper versus lower) is smooth muscle?

Answer 13

(Lower esophageal sphincter)

Question 14

Which cranial nerve provides parasympathetic innervation to the esophagus?

Answer 14

(Vagus nerve)

Question 15

(T/F) Normal esophageal motility is all reflexive.

Answer 15

(T)

Question 16

How do primary and secondary peristalsis differ?

Answer 16

(By their stimulus → primary is elicited by swallowing; secondary is elicited by bolus ‘stuck’ in lumen)

Question 17

What chemical messenger mediates secondary peristalsis?

Answer 17

(Acetylcholine)

Question 18

What portions of the GI tract have striated muscle? Four answers.

Answer 18

(Mouth, pharynx, upper esophagus, and external anal sphincter)

Question 19

The remaining GI tract has primarily what two types of smooth muscle, with some exceptions?

Answer 19

(Circular or longitudinal smooth muscle)

Question 20

The GI tract past the esophagus has primarily circular or longitudinal smooth muscle with two exceptions.

What are the two exceptions?

Answer 20

(Stomach → has oblique muscle, gall bladder → has reticulum/mesh like smooth muscle)

Question 21

What are the four layers of the GI wall from outer to inner?

Answer 21

(Serosa, muscularis, submucosa, mucosa)

Question 22

What does it mean that the GI smooth muscle functions as a syncytium?

Answer 22

(They are all connected, work as a group to achieve coordination → one cells depolarizes, it triggers depolarization of the next via gap junctions)

Question 23

What are the two functions of cyclic contractions?

Answer 23

(Permit mixing of GI content and propel GI content)

Question 24

What are tonic contractions?

Answer 24

(Continuous contractions that relax under neural stimulation)

Question 25

What are the two types of electrical waves in GI smooth muscle?

Answer 25

(Slow waves and spike potentials)

Question 26

Do slow waves cause muscle contraction?

Answer 26

(No)

Question 27

What is the purpose of slow waves?

Answer 27

(Make it possible for contractions to be stimulated more easily by raising resting membrane potential closer to the threshold)

Question 28

Where does slow wave electrical activity in the GI tract originate?

Answer 28

(Interstitial cells of Cajal)

Question 29

What is the frequency of spike potentials in the GI tract affected by? Two answers, types of stimuli.

Answer 29

(Nervous and hormonal stimuli)

Question 30

As you increase the frequency of spike potentials in the GI tract, what effect does this have on contraction of smooth muscle?

Answer 30

(Causes stronger contractions)

Question 31

Does acetylcholine trigger depolarization or hyperpolarization in GI smooth muscle?

Answer 31

(Depolarization)

Question 32

Does nor/epinephrine trigger depolarization or hyperpolarization in GI smooth muscle?

Answer 32

(Hyperpolarization)

Question 33

Are tonic contractions associated with slow waves?

Answer 33

(No)

Question 34

Where is the myenteric plexus located in the GI tract wall and what is its primary role?

Answer 34

(Located between the longitudinal and circular smooth muscle of the GI wall, primarily responsible for motility)

Question 35

Although the myenteric plexus is mostly stimulatory, it does have some inhibitory effects on what structures?

Answer 35

(Sphincters → decreased sphincter tone causing them to relax)

Question 36

Where is the submucosal plexus located in the GI tract wall and what is its primary role? )

Answer 36

(Located between the circular smooth muscle and the submucosa, primarily responsible for secretion, absorption, and local blood flow

Question 37

What nerve is responsible for parasympathetic innervation to the orad half of the GI tract?

Answer 37

(Vagus nerve)

Question 38

What nerves are responsible for parasympathetic innervation to the aborad half of the GI tract?

Answer 38

(Pelvic nerves)

Question 39

Where do sympathetic preganglionic neurons of the GI tract originate in the spinal cord?

Answer 39

(Thoracolumbar)

Question 40

Cholecystokinin is secreted by I cells in the mucosa of the duodenum and jejunum in the presence of what?

Answer 40

(Fat)

Question 41

What effect does cholecystokinin have on the gallbladder?

Answer 41

(Increases contractility of the gallbladder)

Question 42

What effect does cholecystokinin have on stomach motility?

Answer 42

(Inhibits stomach motility)

Question 43

Secretin is secreted by S cells in the mucosa of the duodenum in response to what?

Answer 43

(Acid)

Question 44

What effect does secretin have on GI motility?

Answer 44

(Mild inhibitory effect on GI motility)

Question 45

Gastric inhibitory peptide is secreted by the mucosa of the upper small intestine in response to what?

Answer 45

(Fatty and amino acids)

Question 46

What is the primary stimulus of propulsive movements?

Answer 46

(Distension)

Question 47

What is the law of the gut?

Answer 47

(Peristaltic reflex moving food in an aborad direction)

Question 48

What cells of the stomach secrete hydrochloric acid and intrinsic factor?

Answer 48

(Parietal cells)

Question 49

Where are parietal cells located, proximal or distal stomach?

Answer 49

(Proximal)

Question 50

What cells of the stomach secrete pepsinogen?

Answer 50

(Chief cells)

Question 51

What cells of the stomach secrete mucus?

Answer 51

(Mucous neck cells)

Question 52

What cells of the stomach secrete gastrin and histamine?

Answer 52

(Endocrine or enterochromaffin cells)

Question 53

What is the effect of gastrin on the stomach?

Answer 53

(Stimulates hydrochloric acid secretion)

Question 54

What receptor on parietal cells does gastrin work at to stimulate HCl acid secretion?

Answer 54

(CCK2 receptor)

Question 55

What does pepsinogen need to become pepsin, which then degrades proteins?

Answer 55

(Cleavage by hydrochloric acid)

Question 56

What is the effect of secretin on the stomach?

Answer 56

(Inhibits hydrochloric acid secretion)

Question 57

What effect does cholecystokinin have on hydrochloric acid secretion?

Answer 57

(Inhibits it)

Question 58

What effect do both histamine and acetylcholine have on hydrochloric acid secretion?

Answer 58

(Stimulates it)

Question 59

What receptor on parietal cells does histamine work at to stimulate HCl acid secretion?

Answer 59

(H2 receptors)

Question 60

Release of acetylcholine to stimulate gastric acid secretion is related to what nerve activity?

Answer 60

(Vagus nerve)

Question 61

What is intrinsic factor important for?

Answer 61

(B12 absorption in the ileum)

Question 62

What is the release of secretin from duodenal S cells stimulated by?

Answer 62

(Gastric acid delivery into the duodenum)

Question 63

Chronic vomiting results in what electrolyte deficiencies? Three answers.

Answer 63

(Hyponatremia, hypochloremia, and hypokalemia)

Question 64

How does the mucous layer of the stomach protect the wall from the acid?

Answer 64

(Mucus holds alkaline fluid, which prevents the acidic fluid from affecting the wall)

Question 65

How do NSAIDs cause GI ulcers?

Answer 65

(They block the formation of prostaglandins which are important mediators for mucosal blood flow in the stomach)

Question 66

What are the three phases of gastric activity?

Answer 66

(Cephalic, gastric, and intestinal)

Question 67

Of the three phases of gastric activity, which inhibits gastric activity?

Answer 67

(Intestinal phase)