Digestive physiology Flashcards
What is CCK?
cholecystokinin
a hormone produced in the small intestine.
CCK function
enteric hormone cholecystokinin
triggers your gallbladder and pancreas to contract.
What is GIP?
glucose-dependent insulin releasing polypeptide, also known as gastric inhibitory peptide
an enteric hormone released in the duodenum
GIP function
Glucose-dependent insulinotropic polypeptide, also known as Gastric inhibitory polypeptide or gastric inhibitory peptide, is an inhibiting hormone
released in response to carbohydrate and fat absorption,
enhances the release of insulin following the intake of food.
gastrin function
primarily responsible for enhancing gastric mucosal growth,
gastric motility, and
secretion of hydrochloric acid (HCl) into the stomach.
secretin function
3 main functions:
regulation of gastric acid,
regulation of pancreatic bicarbonate,
and osmoregulation.
What is VIP?
vasoactive intestinal peptide
enteric hormone released in the small intestine
also found in heart and brain
VIP function?
induces smooth muscle relaxation,
stimulates secretion of water into pancreatic juice and bile
etc.
ghrelin function
multifaceted gut hormone
stimulatory effects on food intake, fat deposition and growth hormone release.
Ghrelin is famously known as the “hunger hormone”.
leptin function
Released from adipose tissue
helps inhibit hunger and regulate energy balance so that your body doesn’t trigger a hunger response when it doesn’t need energy
What are the phases of hormonal regulation for digestion(3)?
Cephalic phase e.g. mastication
Gastric phase e.g. changes of motility and secretion initiated in the
stomach in response to stomach distension etc.
Intestinal phase e.g. changes in volume and composition of the lumenal
content affect motility and secretion of the GI tract
Describe the saliva of ruminants.
isotonic, alkaline due to high concentration of HCO3- ,
contains also urea and phosphates;
important for the neutralization of the acids from rumen
What do Cardiac glands secrete
only mucus
Chief cells secrete what
pepsinogen
parietal cells secrete what?
HCl
hydrochloric acid
what is chymosin
also called rennin
an enzyme that is produced by gastric chief cells in newborn ruminants
what neurotransmitter acts to stimulate gastric secretions in response to extrinsic stimuli
acetylcholine
somatostatin function?
a hormone to prevent the production of other hormones in your endocrine system and certain secretions in your exocrine system
name 5 enzymes produced by the exocrine pancreas
amylase
lipase
phopholipase
protease
ribonuclease/DNAribonuclease
what is trypsin
a protease enzyme in the first section of the small intestine that starts the digestion of protein molecules
begins as trypsinogen
trypsin activates all other proteases
What vitamins does the liver store?
vitamins A,B, D, K
Cellololytic bacteria – degrade what components of the cell wall of the plants?
And produce what by result?
-cellolose, hemicellulose, pectin, fructosans
produce VFA
Amylolytic bacteria degrade what and result in?
degrade starch and soluble carbohydrates and result in
acids that reduce pH in reticulorumen
Proteolytic bacteria degrade what to produce what?
degrade proteins to produce amino acids,
VFA
and ammonia
Methanogenic bacteria use what gas to produce methane?
they use CO2 to convert into methane
Rumen gas contains 30-40% NH4 ammonium
Name primary 3 VFAs
acetic acid,
propionic and
butyric acid
In anaerobic conditions, the carbohydrates are converted in reticulorumen into?
volatile fatty acids (VFA),
H2 (hydrogen gas)
CO2
When feeding fiber-rich diet, the proportions of VFA-s are:
acetate, propionate, butyrate
70:20:10
What do methanogenic bacteria convert hydrogen and
carbon dioxide into?
methane (CH4)
What Seven minerals are required in moderate amounts
Calcium,
phosphorus,
potassium,
sulfur,
sodium,
chloride, and
magnesium
What main substrates are used for gluconeogenesis?
pyruvate,
lactate,
glycerol,
amino acids
(mostly alanine,
glutamate, aspartate)
Which 3 amino acids Enable gluconeogenesis
– mostly alanine, glutamate,
aspartate
Amylolytic bacteria degrade what and result in?
degrade starch and soluble carbohydrates and result in
acids tha reduce pH in reticulorumen
name 3 main ketone bodies
acetone
acetoacetate
Beta-hydroxybutyrate
TCA definition
The tricarboxylic acid cycle
same as Krebs cycle and citric acid cycle
name 3 Lipoproteins classified by their density
◦ VLDLs - very low density lipoproteins
◦ LDLs - low-density lipoproteins
◦ HDLs - high-density lipoproteins
describe VLDLs composition and source and function
are mostly triglycerides
The liver is the main source of VLDLs, which transport triglycerides to peripheral tissues (especially adipose).
describe LDLs composition and source and function
have a considerable content cholesterol
are formed in the blood after the unloading of triglycerides from VLDL
LDLs transport cholesterol to the peripheral tissues and regulate cholesterol synthesis
High levels of LDL increase the risk of heart attack
describe HDLs composition and function
have more protein content
HDLs transport excess cholesterol from peripheral tissues to the liver
◦ Also serve the needs of steroid-producing organs
◦ High levels of HDL are thought to protect against heart attack component
glucagon stimulates?
lipolysis,
glycogenolysis,
gluconeogenesis
which pancreatic cells secret glucagon?
alpha cells
what are NEFAs
Non-esterified fatty acids (NEFA, or free fatty acids)
what is Metabolic Rate (MR)
Rate of energy output (expressed per hour) equal to the total heat produced by:
◦ All the chemical reactions in the body
◦ The mechanical work of the body
what is Basal metabolic rate (BMR)
the energy the body needs to perform its most essential activities.
Measured directly with a calorimeter or indirectly with a respirometer.
Factors that Influence BMR
Body surface area,
age,
gender,
stress,
hormones
Factors that influence (total)
metabolic rate
◦ Exercise
◦ Thermoregulation
◦ Digestion and absorption
◦ Growth hormone – metabolic intensity
◦ High temperature
◦ Climate – in hot climate decrease of thyroid hormones
for 10-20 %
◦ Sleep – BMR decreases by 10-15%.
◦ Starvation – metabolic intensity decreases for 20-30%.
what does determination of RQ, respiratory coefficient, measure?
Measures the ratio of the volume of carbon dioxide (Vc) produced
by an organism vs the volume of oxygen consumed (Vo).
Kleiber’s Law
the metabolic rate is proportional to mass
raised to the power of three-quarters, or 0.75
Resting Energy Requirements or RER can be calculated by
by multiplying the animal’s body weight in kilograms raised to
the 3⁄4 power by 70
for example, a 10kg adult neutered dog of healthy
weight needs
RER = 70(10kg)3/4 ≈ 400 Calories/day.
define Torpor
a state of physical or mental inactivity; lethargy.
like a “mild hibernation”
what does aspirin inhibit the synthesis of
prostaglandins (which play a role in fever production)
what compounds are released by lymphocytes or
macrophages to raise temperature
Pyrogens
what compound mediates fever induction in the hypothalamus
Prostaglandin E
3 hormones that inhibit hydrochloric acid secretion?
cholecystokinin
gastric inhibitory peptide
secretin
what is the presumed mechanism behind NSAIDS causing gastric ulcers
gastric mucus secretion is stimulated by local prostaglandins,
NSAIDS inhibit prostaglandin synthesis
the presumption is that the inhibited mucus secretion contributes to ulcer development
primary digestive function of the liver?
to produce bile salts
what compound facilitates lipid digestion?
bile salts (lipid emulsification)
lipase enzyme plays secondary role
define lacteal
the lymphatic vessels of the small intestine which absorb digested fats
what does the pancreas produce in addition to digestive enzymes
sodium bicarbonate
what two pancreatic enzymes are secreted in an already active form?
pancreatic amylase
lipase
what is enterohepatic circulation?
the recycling of bile salts between the digestive tract and the liver
what compound forms gallstones?
excess cholesterol that precipitates out of the bile it should be dispersed in
Name the 6 main electrolytes.
calcium
chloride
magnesium
phosphate
potassium
sodium
How does calcitriol increase calcium absorption?
low blood CA+ stimulates the kidneys to produce calcitriol hormone (a form of vitamin D)
calcitriol in turn increases Ca+ absorption by increasing Ca+ transport proteins in enterocytes
