Digestive - 2 Flashcards
What is the function of the oesophagus?
Transports food from the mouth to the stomach
Protects against abrasive fragments of food
What is a unique feature of the oesophagus epithelium? What is this features function
Has multi-layered thick stratified squamous epithelium that act as sacrificial cells for protection
What is a unique feature of the oesophagus external muscle layer? What is this features function
The top third of the oesophagus contains skeletal muscle to allow for rapid and voluntary control of swallowing
What is a unique feature of the oesophagus serosa? What is this features function
Most of the length of the oesophagus is not inside a body cavity so it is instead covered with a fibrous adventitia (outer layer that connects oesophagus to trachea and surrounding) until it is in the abdomen and covered in serosa
What is the primary function of the stomach?
Storage
What are some of the secondary functions of the stomach?
Secretion of acid, enzymes and mucus
Digestion of proteins
Absorption of water and ions
Transport
Label the diagram
What are the cardia and pylorus mostly made of?
Mucous glands
What is the function of the funds and body?
Secrete acid, enzymes and mucus
Label cell types in the diagram and explain their function
What is an issues that parietal cells have due to their function (i.e. production HCl)? How is this overcome?
They secrete acid (HCl) which could kill them
They secrete H+ and Cl- into the lumen which then forms HCl outside the cell
Other than acid do parietal cells secrete? What is its function and why is it important?
It also secretes intrinsic factor which is essential for B12 absorption which is essential for red blood cell synthesis
What is an issue that chief cells have with function (i.e. secreting pepsin)? How is this mitigated
Pepsin breaks down proteins and if it is released in its active form inside the cell then it will break down the cell. This is overcome as the pepsin is only active in acidic environments which is in the gastric pit, away from the gastric glands where the chief cells reside
What is the process called when a cell digests itself (i.e. chief cells releasing pepsin instead of pepsinogen)?
Autodigestion
What happens to the surface mucous cells over time?
They get disintegrated by the acid and enzymes
What happens if the surface mucous cells don’t provide protection?
Ulcers
Gastrin cells are endocrine and chief cells are exocrine, what does this mean?
Gastrin cells release hormones that go directly into the blood
Chief cell release their hormones onto the surface of tissue
What stimulates gastrin cells? Why?
Eating food/water etc. to get all the cells in the stomach to perform the functions faster because of the dilution of the acid
What is the function of bile?
It emulsifies large lipid globules into smaller ones to increase the surface are for digestion
What are the functional cells of the liver? What can they do?
Hepatocytes can perform more than 500 different metabolic functions including (know 3):
glycogen/glucose storage and release
red blood cell recycling
bile synthesis and secretion
toxin removal
What does each hepatocyte require to function?
Access to nutrient rich blood from the intestine
Access to oxygenated blood
Access to bile ducts (that drain to gall bladder FYI)
Label the hepatocyte
How does the bile that is produced by the hepatocyte exit the liver?
It travels via the bile canaliculus (and doesn’t leak because of tight junctions FYI)
What do the endothelial cells on the hepatocytes do? What special features allows this?
They filter out large particles (i.e. proteins, red blood cells…)
They are fenestrated (i.e. have holes in them)
Label the diagram of different types of vessels going into/out of the liver and what they do
What is the movement of blood and the nutrients (and specify the function of the blood) in the liver?
Nutrient rich (but deoxygenated blood from the hepatic portal vein) blood from the small intestine and oxygenated blood (from the systemic circuit) transport nutrients from the outside of the tubule structure to the central vein
What is the movement of bile from the liver?
From the hepatocytes through bile ducts that link up to tributary of bile duct (i.e. shared duct) to gall bladder (for storage)
What is the sinusoid?
It is the blood vessel that runs though the hepatocytes to the central vein
