Lecture 3 - Secretions

Question 1

What kind of digestion occurs in the large intestine

Answer 1

Microbial digestion

Question 2

What is digested in the L.I.? Why?

Answer 2

Fiber
Broken down into glucose (can no longer be absorbed) so turn that into volatile f.a.’s which can be utilized by the host as energy

Question 3

Three volatile f.a. produced by fiber digestion

Answer 3

Acetate (2C)
Propionate (3C)
Butyrate (4C)

Question 4

Four requirements for microbial digestion

Answer 4

1. Fluid environment
2. Neutralized environment
3. Continuous removal of end-products by absorption
4. Long retention time of digesta (breaking down fiber is slow)

Question 5

What needs to occur for short chain fatty acids to be absorbed

Answer 5

H (from CO2 hydration or Na/H exchange) needs to protonate SCFA to neutralize them, making them lipid soluble

Question 6

What form are short chain fatty acids in at neutral pH?

Answer 6

Acid form (water soluble; not lipid soluble)

Question 7

How are short chain f.a. absorbed?

Answer 7

Nonionic diffusion (no E)

or

Apical membrane SCFA-HCO3 exchange (transporter–E required)

Question 8

Where are SCFA absorbed

Answer 8

Transporters are in small and large intestines

Question 9

What percent of calf mortality is due to failure of passive transfer?

Answer 9

39%

Question 10

What is transferred when calves drink colostrum

Answer 10

Antibodies (immunoglobulins; IgG)

Question 11

What percent of heifer calves have failure passive transfer?

Answer 11

41%

Question 12

Calves with FPT have…

Answer 12

Lower BW
Lower average daily gain
Higher vet costs
Reduced milk production

Question 13

“Leaky gut” refers to…

Answer 13

in the first 24h of life when the gut is still able to absorb large proteins

Question 14

Immunoglobulins are absorbed through…

Answer 14

Pinocytosis (into vesicles)

Question 15

What happens to pinocytotic capability over time?

Answer 15

It is lost over time

Question 16

What is butyrate? What does it do to the gut?

Answer 16

Short chain f.a.
Drives gut development (closure) decreasing IgG absorption if given after birth

Question 17

Pinocytotic capacity is _________. Pinocytosis is ______________ (selective/non-selective).

Answer 17

Limited
Non-selective

Question 18

Reaction of H2O & CO2 to gut secretions

Answer 18

H2O + CO2 <-> H2CO3 <-> HCO3 + H+

Question 19

Bicarbonate is part of what secretions? H+?

Answer 19

HCO3 = salivary and pancreatic
H+ = gastric

Question 20

Important salivary secretory glands?

Answer 20

Zygomatic gland, parotid gland, mandibular gland, sublingual gland

Question 21

Composition of salivary secretions

Answer 21

Buffer (HCO3)
Na, Cl
Amylase (except ruminants/carnivores)

Question 22

What is amylase? Where is it made

Answer 22

enzyme, or special protein, that helps you digest carbohydrates

Most made by pancreas and salivary glands

Question 23

Function of salivary secretions

Answer 23

Moisten food to facilitate deglutition
Neutralize acids from fermentation (ruminants)

Question 24

How are salivary secretions controlled

Answer 24

Flow increased by cholinergic stimulation
Salivary center (medulla)
Reflex stimulation from mechanoreceptors in mouth/stomach

Question 25

Acetylcholine activates what salivary glands

Answer 25

Parotid gland and submandibular gland

Question 26

Roles of the stomach (7)

Answer 26

Storage Protein denaturation (HCl) Mixing (mechanical digestion) Pepsinogen Digestion (proteins) Bacteriostatic (prevent pathogens) B-12 absorption

Question 27

Four parts of the glandular stomach

Answer 27

Esophageal part Cardia Fundus + corpus Pylorus

Question 28

Fundus + corpus region of the stomach aka

Answer 28

Proper gastric

Question 29

What is secreted by the cardia

Answer 29

Mucus

Question 30

What is secreted by the diff cells of the proper gastric region

Answer 30

Mucus Parietal cell = HCl, intrinsic factors (B12) Chief cell = pepsinogen

Question 31

What do intrinsic factors do

Answer 31

Facilitate B12 absorption into the ileum (binds Vit B12, carries it to end of SI, recognized, B12 absorbed)

Question 32

What does the pyloric region of the stomach secrete

Answer 32

Mucus and gastrin

Question 33

What activates pepsinogen into _________

Answer 33

Acidic conditions activate it into pepsin (digests proteins)

Question 34

Role of HCl in gastric secretions (5)

Answer 34

Breakdown collagen Protein uncoiling Bacteriocidal Activate pepsinogen Optimum pH

Question 35

What cells secrete pepsinogen

Answer 35

Chief cells

Question 36

What molecules stimulate gastric HCl secretion**

Answer 36

1. Acetylcholine (stimulates histamine release) 2. Gastrin (enters circulation, stimulates parietal cells, histamine release) 3. Histamine (stimulates local parietal cells)

Question 37

What type of cell releases HCl

Answer 37

Parietal

Question 38

Gastric secretions include...

Answer 38

HCl, pepsin

Question 39

What molecule inhibits gastric secretion

Answer 39

Somatostatin released when pH is low

Question 40

What does paracrine mean

Answer 40

Stimulates local cells (neighbours)

Question 41

What molecules turn parietal cells on

Answer 41

Gastrin, histamine, ACh

Question 42

In gastric secretion, bicarbonate enters the _______ while HCl enters the ______

Answer 42

Blood, gastric lumen

Question 43

Why don't acids and pepsin digest the stomach (epithelial cells)

Answer 43

Protected from acid by mucous layer Bicarbonate secreted by epithelial cells trapped in mucous layer (buffer)

Question 44

Epithelial cell mucous secretion is increased by...

Answer 44

Cholinergic stimulation Mechanical stimulation

Question 45

What is the main cause of ulcers in humans

Answer 45

Helicobacter pylori

Question 46

What does helicobacter pylori do to the stomach environment

Answer 46

Increases pH, damages mucous layer to allow acid to reach epithelial wall

Question 47

Up to what % of growing pigs show lesions of ulcers at slaughter? What % of sows?

Answer 47

60%, 5%

Question 48

Factors contributing to ulcers in pigs

Answer 48

1. Nutritional (low protein, low fiber, high E) 2. Physical diet (particle size, moisture) 3. Management (irregular feeding, stress, water availability, infections) 4. microbial (helicobacter suis)

Question 49

Clinical signs of ulcers in pigs

Answer 49

Pale animal, breathlessness, vomiting, dark feces, weight loss, death

Question 50

Is Helicobacter suis zoonotic

Answer 50

It has been found in a veterinarian

Question 51

What does the pancreas secrete

Answer 51

Proenzymes (e.g. amylase) Enzymes Bicarbonate

Question 52

What cells produced bicarbonate

Answer 52

Duct cells

Question 53

Pancreatic secretions are adjusted according to...

Answer 53

acid and nutrients entering duodenum

Question 54

Difference in pancreatic secretion pattern btw horses and ruminants

Answer 54

Ruminants = continuous secretion (4-5L/day) Horses = constant but increases after eating begins (30-35L/day)

Question 55

What breeds is exocrine pancreatic insufficiency common in? Symptoms?

Answer 55

German Shepherds, Rough Collies Weight loss, greasy/foul smelling diarrhea, dry/dandruffy coat

Question 56

What is exocrine pancreatic insufficiency? Treatment?

Answer 56

Pancreatic acinar atrophy (no digestive enzymes sent to gut) Treat with pancreatic enzyme replacement therapy (PERT) = oral pancreatic enzymes

Question 57

Causes of exocrine pancreatic insufficiency

Answer 57

Genetic in dogs Chronic pancreatitis Obstruction of pancreatic duct

Question 58

Where is bicarbonate secreted by the pancreas

Answer 58

Into the duct lumen (gut environment)

Question 59

Secretory diarrhea can be caused by...

Answer 59

1. Prostaglandin E in response to damage or reactive oxygen species 2. Serotonin induced by toxins 3. Cholera toxin 4. Enterotoxigenic E. coli Slides 42-48****

Question 60

What cells release somatostatin? Gastrin?

Answer 60

Somato = D cells Gastrin = G cells