Lecture 24: Digestive Physiology Flashcards
(18 cards)
What are the four accessory organs in digestion?
- Salivary glands
- Liver
- Gallbladder
- Pancreas
Which are the three paired major salivary glands?
- Parotid
- Sublingual
- Submandibular
What are the functions of saliva?
- Cleanse the mouth
- Dissolve food chemicals which allows us to taste.
- Moisten food to aid in swallowing
- Initiates chemical digestion of starch with amylase.
What does saliva consist of?
- Mucin (Moistens and binds to food particles)
- Salivary amylase (breaks down starch molecules)
- Electrolytes
- Lysozyme (Targets bacterial cell wall structure)
How many lobes does the liver have?
The liver has 4 lobes. 2 anterior (right and left) and 2 posterior.
Which are the three important liver vessels?
- Hepatic portal vein: Delivers nutrient rich blood coming from the digestive system for processing.
- Hepatic artery proper: Delivers oxygen rich blood to hepatocytes.
- Common hepatic duct: Collects bile, produced by hepatocytes and transports it to the duodenum or if not required travels through the cystic duct to the gallbladder.
What are liver cells composed of?
They are composed of functional units called liver lobules. Each lobule has a hexagonal shape and a central vein.
What are liver lobules composed of?
- Branch of the hepatic artery
- Branch of the hepatic portal vein
- Bile duct
Outline the steps of blood flow through a liver lobule.
- Hepatic artery and portal vein branch
- Sinusoid capillaries
- Central vein
- Hepatic vein
- inferior vena cava
What are the functions of the liver?
- Store glucose in the form of glycogen
- Store lipid soluble vitamins and iron
- Inactive chemicals like alcohol, hormones, drugs and poisons
- Convert ammonia to urea to be excreted as urine
- Degrade old and damaged erythrocytes. Byproduct is bilirubin which is incorporated in bile.
- Produce and releases bile
What is the function of bile?
Bile salts help break down fats into tiny droplets.
What is Jaundice?
Yellow discoloration of the skin and sclera of the eyes caused by an accumulation of bilirubin in the blood. Symptom of blockage of the biliary duct system or liver disease.
What are gallstones?
Gallstones are formed when bile contains a large among of cholesterol. Obesity is a risk factor
Which are four of the pancreatic enzymes?
- Amylase for starch
- Proteases for proteins
- Lipases for lipids
- Nucleases for nucleic acids
How does carbohydrate digestion take place?
- Brush border enzymes help breakdown sugar into simpler forms.
- The simple sugars enter the cell with salt and are co-transported.
- The sugars leave the backside of the cell by facilitated diffusion.
- They move into capillaries through intercellular clefts.
How does protein digestion take place?
Released amino acids are co-transported with sodium ions into enterocytes as monosaccharides.
Facilitated diffusion occurs across the basolateral membrane and amino acids are taken up into capillaries through intercellular clefts.
How does lipid absorption take place?
- Micelles release fatty acids and monoglycerides near the apical surface of enterocytes and enter via simple diffusion.
- Monoglycerides and fatty acids are reformed into triglycerides and packaged into lipoproteins called chylomicrons and released via exocytosis.
- Chylomicrons are too large to enter the blood capillaries and instead enter lacteals. (lymph capillaries)
What is the purpose of chylomicrons?
Triglycerides are enclosed by phospholipids and proteins that are hydrophilic so they can be transported into lymph and blood.
