Digestive Flashcards
What is the biggest immune system?
The Gut. You are what you eat, needs probiotics and prebiotics
What factors can influence composition and function of human gut microbiota
- Birth mode
- Breast feeding
- Geography
- Diet
- Exercise
- Disease
- Ageing
- Drugs
Anabolism v.s. Catabolism
Anabolism = Building = using amino acids to build proteins
Catabolism = breaking down = proteins to amino acids.
Essential nutrients = cant make these, must get food.
Salivary Glands
3 pairs = exocrine
Carbohydrate digestion starts in mouth due to amylase
Parotid Salivary Glands
Produce serous secretion - Enzyme salivary amylase = breaks down starches into glucose, maltose
Sublingual Salivary Glands
Produce mucous secretion - acts as a buffer and lubricant
Submandibular Salivary Glands
Secrete buffers, glycoproteins (mucins) and salicary amalyse
Do alligators chew food?
NO!
Functions of the stomach
Store Foods
- Release gastric acids = HCl = strong acid; kills
bacteria, breaks down proteins & activates
pepsinogen - Releases pepsinogen = inactive -> pepsin is active
- Mucous is released = 2 types
- Release intrinsic factor = important for vitamin B12
absorption which is needed for RBC production - Release gastrin = a hormone that stimulates gastric
activity
What are the Types of Mucous?
- Protects stomach
- Keeps digesting food slimy
- Someone w/ gastric reflux can damage esophagus bc. no protection in esophagus
What are parietal, chief, and g-cells
Parietal: releases HCl & Intrinsic factor
Chief Cells: Pepsinogen
G-Cells: Gastrin = hormones
What does HCl do?
- Kills microorganisms
- Denatures proteins and inactivates enxymes in food
- Helps break down plant cell walls and connective tissue in meat
- Activates pepsin = digests proteins
Active process = Use ATP
Explain the process of HCl secretion from parietal cells
- CO2 + H2O -> H+ + HCO3- in presence of carbonic anhydrase
- H+ is actively pumped out via H+/K+ ATP-ase K+ will leak out
- HCO3- is exchanged for Cl- = antiporter
- CL- moves out through cell via channel = facilitated diffusion
- Alkaline tide = increases in HCO3- after feeding = metabolic alkalosis
Metabolic Alkalosis = fixed by hypoventilation
pH is very acidic = 1-2
How is acid and enzyme production by gastric mucosa regulated?
- Controlled by the CNS
- Regulated by short reflexes of ENS = Enteric Nervous System = brain of the gut
- Regulated by hormones of digestive tract
What are the 3 phases of gastric activity
- Cephalic phase
- Gastric phase
- Intestinal phase
What role does the small intestine do?
Roles in digestion and absorption of nutrients
What is the Duodenum?
- the segment of small intestine closest to stomach
- “mixing bowl” that receives chymes from stomach and digestive secretions from pancreas and liver
- modify it HCl & use HCo3 to neutralize acid
Function:
- Receives chyme from stomach
- Neutralize acids before they can damage
absorptive surfaces of the small intestine. Lost of
bicarbonate to neutralize H+ from HCl and lots
enzymes
HCO3- + H+ -> CO2 +H2O
What are the components of the Small Intestine?
The Jejunum and The Ileum
What is the Jejunum?
- Middle segment of small intestine
- Is the location of most
a. Chemical digestion = lots of enzymes =
lipases (Fats) ; amylases (carbs); proteases
(proteins)
b. Nutrient absorption
- Is the location of most
What is the Ileum?
- Final segment of small intestine
- End at the ileocecal valve, a sphincter that
controls flow of material from the ileum in to the
large intestine.
What does Absorption Cells do?
- Absorb nutrients
- Have microvilli
What does Goblet Cells do?
- Release mucous into Small Intestine
What does Enteroendocrine cells do?
- Secretes lots of hormones
What does Paneth Cells do?
- Release antimicrobial agents into Small Intestine such as lysosomes.
- Capable of phagocytosis
What affects the lining of the Small intestine?
- Parvo affects the small intestine by destroying the microvilli
What is Pancreatic Juice? What does it do?
- Contains a variety of enzymes = Pancreatic amylase,
proteolytic enzymes (trypsin, secreted as
trypsinogen), chymotrypsin (chymotrypsinogen,
Pancreatic lipase - Is alkaline: high concentration of bicharbonate ions.
Neutralizes gastric acid - Regulated by hormones: secretin and
cholecystokinin (CCK)
How is Pancreatic Juices secreted?
- Entrance of Chyme into duodenum
- Secretion of Bicarbonate: depends on secretin
secreted by duodenum - Secretion of digestive enzymes: depends of CCK
secreted by duodenum
What composes the Liver
Hepatic Blood Supply
- 1/3 of blood supply = arterial blood from hepatic
artery proper
- 2/3 venous blood from hepatic portal vein,
originating from esophagus, stomach, small
intestine and most of the large intestine =
nutrient rich
What are the Metabolic Activities of the Liver
- Carbohydrate metabolism: stabilizes blood glucose =
store glycogen - Lipid metabolism: regulates circulating lvls of
triglycerides, fatty acids, and cholesterol =
lipoproteins = high density and low density - Amino Acid metabolism: removes excess amino
acids = use these in gluconeogenesis - Waste product removal: ammonia to urea, Ammonia
is lipid soluble = cna get into cells by diffusion.
Urea
is part of protein catabolism - Vitamin storage: Fat soluble vitamins and vitamin
B12 - Mineral storage: converts iron to ferritin from RBC
recycling - Drug inactivation: removes and breaks down drugs
- Milk thistle help with liver health.
What are the Hematological functions
- Phagocytosis and antigen presentation: kupffer cells
engulf old and damaged RBCs = protect liver - Synthesis of plasma proteins: albumins, transport
proteins, clotting proteins; albumin = helps to
maintain colloid osmotic pressure - Removal of circulating hormones: absorption and
recycling of EPI, NE, Insulin thyroid hormones
and steroid hormones. - Removal of antibodies: absorbs and breaks down
antibodies - Removal or storage of toxins: lipid soluble toxins are
absorbed and stored
What are the functions of Bile?
- Dietary lipids are not water soluble: lipid droplets
- Mechanical processing in stomach creates large
drops containing lipids - Pancreatic lipase is not lipid soluble
- Interacts only at surface of lipids droplet =
emulsification
Bile salts break down droplets apart = emulsification
- Increases surface area exposed to enzymatic attack
- Creates tiny emulsion droplets coated with bile
salts.
What is the function of Gallbladder?
- Stores bile. Liver makes Bile
- Releases bile into duodenum, but only under
stimulation of Cholecystokinin (CKK) - No CCK = Hepatopancreatic sphincter remains
closed = bile enters cystic duct and is stored
gallbladder.
What are the functions of the Large Intestine?
- Churning driving contents of colon into rectum
- Bacteria in Large Intestine convert proteins to
amino acids, break down amino acids and
product vitamin B and vitamin K - Absorption of some H2O, Ions, and Vitamins
- Formation of feces
- Defecation (emptying rectum)
What are the absorption in the large intestine
- Vitamins = organic molecules
- Important as cofactors or coenzymes in
metabolism
- Normal bacteria in colon make three vitamins
that supplement diet
1. Vitamin K (fat soluble): required nu liver for
synthesizing clotting factors
2. Biotin (water soluble): important in glucose
metabolism
3. B5 (water soluble): required in manufacture
of steroid hormones
