2.3. GI System Flashcards
Functions of mouth
- Ingestion of food
- Mechanical breakdown- food mixes with saliva containing enzymes
- Carries food through the pharynx and oesophagus to stomach
Functions of oesophagus
- Moves food from mouth to stomach
- Food propulsion accomplished by deglutition (peristalsis)
Function of liver
- Secretes bile which emulsifies fats by breaking down into smaller pieces
Function of gallbladder
stores bile
Functions of stomach
- Mechanical breakdown of food by peristalsis
- Protein digestion occurs here, by hydrochloric acid and pepsin
Functions of pancreas
- Secretes digestive enzymes
- Supplies enzymes that digest chyme and bicarbonate that neutralise HCL
Function of small intestines
- Digestion is completed and virtually all absorption occurs (microvilli, villi, circular folds)
Functions of large intestines
- Absorb remaining water from indigestible food residues
- Stores residues temporarily
- eliminate them from the body as semisolid feaces
Function of anus
- The opening at the end of the GI that allows faeces to leave the body
Explain difference between peristalsis and segmentation
Peristalsis primarily propulsive whereas, segmentation is the mixing of food.
Peristalsis occurs all the way from oesophagus to large intestine but segmentation only occurs in the small intestine.
Food is moved distally in peristalsis and forwards then backwards in segmentation.
General GI tract in pregnancy
alteration, significance/physiology, effect of which hormone
- Appetite increases, cyclical patterns of appetite, cravings and aversions
- hCG, leptin, oestrogen, progesterone
Mouth in pregnancy
alteration, significance/physiology, effect of which hormone
- Gums become hyperaemic, oedematous (fluid filled) and spongy. Saliva becomes more acidic
- Oestrogen increases blood flow to the gums and changes the connective tissue consistency. This makes the gums more vulnerable.
Oesophagus in pregnancy
alteration, significance/physiology, effect of which hormone
- Heartburn
- Progesterone relaxes the lower sphincter, causing a back flow of partially digested food and stomach acid.
Stomach in pregnancy
alteration, significance/physiology, effect of which hormone
- Acid secretion decreases, secretion of pepsin falls, decreased gastric motility
- Slow emptying of stomach, increased pulping of food, nausea, delay absorption of glucose
- Progesterone
Small/large intestine in pregnancy
alteration, significance/physiology, effect of which hormone
- Gut tone and motility decreases, abdominal distension, constipation, increased iron absorption, raised levels of angiotension and aldosterone
- Progesterone relaxes smooth muscle- increased water absorption. Duodenal villi enlarge. Increase in sodium and water absorption from colon- increased flatulence.
Gallbladder in pregnancy
alteration, significance/physiology, effect of which hormone
- Flacidity, increased bile storage but decreased emptying rate
- Bile contains less cholesterol because water resorption by epithelium cells is decreased
- Progesterone affects smooth muscle tone
Liver in pregnancy
alteration, significance/physiology, effect of which hormone
- Hepatic displacement- due to gravid uterus
- Increased glycogen and triglyceride storage
- Decrease in albumin (due to plasma volume expansion), increase in fibrinogen and increased cholesterol synthesis
- Increased hepatic perfusion- increase in portal venous return
- Oestrogen
What are some theories given for causes of NVP?
- Evolutionary mechanism: protects embryo by causing woman to physically expel and avoid foods which may contain teratogenic and abortifacient chemicals.
- Stimulates early placental growth: reduces maternal energy intake and suppresses maternal tissue synthesis so nutrient partitioning favours placenta.
- hCG peaks in 1st trimester
What is HYPEREMESIS GRADIVARUM?
What signs and symptoms indicate it?
Severe and persistent nausea and vomiting which leads to nutritional deficiencies .
May require hospitalisation to correct the electrolyte and fluid imbalances.
What are some known risk factors of HG?
- Previous HG
- Hyperthyroid disorders
- Pre-existing psychiatric disorders
- Molar pregnancy
- GI disorders
- Multiple gestation with a female and male twin
