Lecture32: Physiology Of Large Intestine Flashcards
Name 2 functions of the Large Intestine
Storage of faecal matter, water and electrolyte absorption and thick mucinous secretions
What does the mucinous secretions contain?
K+ and HCO3
What is responsible for driving the Potassium entry into the lumen?
Na (sodium)
What are HCO3 ions secreted in exchange for?
Cl- ions
What increases intestinal secretions?
VIP
What decreases intestinal secretions?
Adrenaline and somatostatin
What does excessive loss of K+ lead to?
Kypokalemia
What does loss of HCO3 lead to?
Acidosis
Where is K+ absorbed?
Distal colon
What is sodium absorbed in exchange for?
Potassium
What does Aldosterone do?
Increases water and sodium reabsorption via synthesis of sodium channels
What do Glucocorticoids do?
Stimulate sodium transport via increasing the number of ATPase pumps
What does angiotensin do?
Stimulates water and Sodium absorption in the colon
What does Vasopressin do?
Decreases water absorption
What do bacteria do?
Convert primary bile acids to secondary bile acids
What do anti inflammatory drugs treat and where are they administered?
Rectum, to treat ulcerative colitis
How do you avoid constipation?
Eating foods rich in fiber
How does fiber-rich food avoid constipation?
They are indigestible thus trigger mechanoreceptors
The Circular layer, what is needed to elicit contractions?
Acetylcholine
What does acetylcholine do?
Increase the time of the slow wave oscillations
Name 2 reflex controls of the colon?
Gastro and colono-colic
What is defecation by definition?
A reflex to sudden distention of the rectum
What 2 reflex take part in the Automatic spinal mechanism of defecation?
Both gastro and duodeno-colic
What do these 2 reflexes do?
They stimulate mass movement of the colon contents into the rectum
