Lecture : part 4 Gastrointestinal system

41 views2 pages

lxsaantony

13 Jan 2023

School

Philadelphia University

Department

Biology

Course

BIOL-204L

Professor

For unlimited access to Class Notes, a Class+ subscription is required.

Document Summary

Gastric motility serves as a reservoir, pepsins digest proteins, and intrinsic factor is crucial for vitamin b12 absorption. Activities of hcl: facilitation of pepsin activation. It makes the conditions for pepsins to function perfectly: microbes are eliminated or stopped, stimulates secretions from the small intestine, facilitates calcium and iron absorption in the small intestine. When the ph rises, the cell passively absorbs co2 and h2o across the basolateral membrane. By using h2co3, carbonic anhydrase catalyses the conversion of co2 and h2o into h+ and hco3-: across the basolateral membrane, the anion (cl-/hco3-) exchanger removes hco3- ions generated by carbonic anhydrase from the cell. Intrinsic factor is a glycoprotein released by the stomach"s parietal cells. Early in gastric emptying, when the ph of the stomach chyme is more than 3, stimulation takes precedence. Stomach chyme < ph 3, then inhibition predominates later in gastric emptying. Tonic contraction pylorus- controls the emptying of food into the duodenum.

Related Questions

1) Look up the structures of the following molecules. For each carbon atom, indicate its oxidation state. Calculate the average oxidation state of the carbon atoms in each.

Glucose

Pyruvic acid

Citric acid

Oxaloacetic acid

Carbon dioxide

2) Consider the following hypothetical cell. Initially, the cell has an equal number of positive and negative charges (cations and anions) on either side of its plasma membrane (extracellular, intracellular). There are equal concentrations of Na+, K+, and Cl- on either side of the plasma membrane. Consider the effects of the following events, in sequence, upon the ion concentrations and charge distributions (membrane electrical potential).

A. NKA proteins are activated in the plasma membrane. How does this affect the ions and the membrane electrical properties?

B. A small number of K+ channels open in the plasma membrane. How does this affect the ions and the membrane electrical properties?

C. An even larger number of Na+ channels open in the plasma membrane.

D. The Na+ and K+ channels close. Cl- channels open.

3) Pancreatic juice contains approximately 150 mM Na+. How do these Na+ ions contribute to the absorption of amino acids and sugars? Explain how 100% of an amino acid can be absorbed from the small intestines. HINT: intestinal epithelial cells have NKA, numerous cotransporters (symporters) and facilitated diffusion proteins.

1. Food passing into the small intestines is very acidic from the hydrochloric acid released by the lining of the stomach and mixed in by churning. The pH of the stomach is about 2 whereas the pH of the small intestines is about 8. A buffer, bicarbonate, is released by the pancreas and used to convert the pH 2 chyme solutions (food) to a pH 8. Explain the importance of the buffer to the continued digestion of your food.

2. Your enzymes have specificity. With this in mind, explain why you need no less than ten different enzymes working on digestion in your small intestines.

3. In a eukaryotic cell there is one nucleus and several mitochondria. Both of these organelles are surrounded by a membrane and contain DNA. With your knowledge of a minimal cell, the cell theory and the endosymbiotic hypothesis, explain whether or not they fit the criteria to be considered a cell and support your answer.

4. Your pancreas cells produce many digestive enzymes necessary for the final digestive processes in your small intestines, including pancreatic amylase to complete the digestion the starches in your food. The pancreatic amylase is secreted from the cells of the pancreas and is carried to the small intestine in the common bile duct. Describe the pancreas cellâs processes that it must go through from production to secretion of this enzyme (amylase).

tanhyena895

TRUE OR FALSE FOR 31-36

31. GLUTs are uniporters that use ATP hydrolysis for energy.

32. GLUT1 transports glucose across the blood brain barrier.

33. GLUT2 initially transports glucose into the pancreas after eating, allowing insulin to be released into the bloodstream.

34. After insulin signaling, GLUT4 is transported to the membrane of various cells to increase glucose transport in tissues (But not if you have Type II Diabetes).

35. If the plasma membrane of an animal cell was made entirely permeable to Na+, the Na+/K+pump would continue to pump ions and hydrolyse ATP, but not build a Na+gradient.

36. Passive carriers are localized to the basolateral membrane of epithelial cells, activate transporters are localized to the apical membrane.

Lecture : part 4 Gastrointestinal system

Document Summary

Get access

Related Documents

PNB 2265 Lecture Notes - Lecture 20: Pylorus, Enterochromaffin-Like Cell, Histamine Receptor

BIO 252 Lecture Notes - Lecture 12: Gastroesophageal Reflux Disease, Esophageal Hiatus, Lamina Propria

BIOL373 Lecture Notes - Lecture 21: Cystic Fibrosis, Pancreatic Duct, Centroacinar Cell

Related Questions