comparative GI

what composes the pre gastric system in birds

beak -> esophagus -> crop

crop

an extension of esophagus that acts as a storage pouch

what composes the gastric system in birds

proventriculus -> gizzard

proventriculus

the glandular stomach

functions of the proventriculus

1. receives food

2. secretes mucus

3. secretes HCl and pepsinogen

gizzard

the muscular stomach

gizzard function

contains rocks to facilitate grinding

what is a common characteristic of both proventriculus and gizzard

periodic retropulsion of duodenal contents are pushed back into stomach

what is a special behavior raptors do

regurgitate pellets

small intestine of birds

same as mammals

cecum of birds

paired

large intestine of birds

short colon with short villi that extends into the lumen

what type of movements occur in the large intestine of birds

antiperistalsis

how do birds excrete ammonia

as uric acid

where does fermentation take place in birds

ceca

cloaca

single opening for digestive, reproductive, and urinary systems

vent

opening to the outside in birds

how do aquatic reptiles excrete nitrogenous waste

as ammonia

how do terrestrial reptiles excrete nitrogenous waste

as uric acid

what is unique to the reptile GI tract

modified salivary glands to produce poison (not in all species)

what part of the reptile GI tract is similar to birds

cloaca

what part of the reptile GI tract is similar to mammals

all other systems (esophagus -> monogastric stomach -> intestines)

amphibian GI tracts are most similar to what

mammals

what is the one feature that birds, reptiles, and amphibians all LACK compared to mammals

diaphragm

how do birds/reptiles/amphibians breathe without a diaphragm

lungs are adhered to the body wall or they have air sacs

torpor

type of hibernation where animal becomes hypothermic for only a few days/weeks

how do bears hibernate

they become hypothermic and stay that way the whole time

what cues signal a change of season for hibernation

temperature, daylight, and genetics

how do animals store fuel

1. store food

2. become obese

3. fatten up via insulin

what type of fat is used for fuel storage

white adipose

what type of fat is used for metabolic heat/thermogenesis

brown adipose

why do hibernators use fat over carbohydrates

fatty acid oxidation provides double the energy production

how do hibernators produce non-shivering thermoregulation

slow cellular processes which lowers body temperatures

what do bears do with the urea produced during hibernation?

recycle it into amino acids

How does the GI tract function during hibernation? (5)

1. prolong absence of luminal nutrition

2. decreases intestinal blood flow

3. inactivates carbohydrate metabolism

4. activates lipid metabolism

5. increases pancreatic lipase

what stays the same in the GI tract function during hibernation? (3)

1. epithelial function

2. microvilli preserved

3. GI flora - live off mucins

prolonged absence of luminal nutrition during hibernation results in what (3)

1. atrophy of mucosa

2. decrease in villus height

3. decrease in crypt depth