Gastrointestinal System Flashcards
What are the function of the GI tract?
digestion and elimination
Explain the function of ‘digestion’ in the GI tract
the ‘breaking down’ (mechanical and chemical) of food and fluid into simple chemicals that can be absorbed and transported throughout the body
Explain the function of ‘elimination’ in the GI tract
waste products are disposed of through the excretion of faeces
The digestive system is made up of the GI tract. Describe it…
This is a series of hollow organs joined in a long, twisted tube from the mouth to the anus.
Name the 6 organs involved in the GI tract
- mouth
- oesophagus
- stomach
- small intestines
- large intestines
- anus
What is meant by an accessory organ?
in relation to the digestive system, is an organ which aids digestion but is not directly part of the digestive tract
What are the accessory organs of the GI tract?
- teeth
- tongue
- salivary glands
- gall bladder
- pancreas
- liver
Explain the role of the mouth in the GI tract?
- chewing
- food reduced to a bolus
- salvia starts to dissolve food
- teeth chop and grind food into small pieces
- lingual lipase activated in stomach to break down fats
- tongue pushes food to back of throat
- nasal cavity and windpipe close to prevent aspiration
- as you swallow the digestive process becomes involuntary
Explain the role of the oesophagus in the GI tract?
- food passes through the pharynx into oesophagus
- involuntary peristalsis involves muscular waves of movement to push the food down the stomach
Explain the role of the stomach in the GI tract?
- a temporary holding station
- hydrochloric acid and enzymes break down the protein
- mucus lining the stomach allows us to eat larger amounts of food
- liquids pass through in minutes
- acts as a food mixer, grinds food into smaller pieces
Explain the role of the small intestines in the GI tract?
- bile enters the duodenum
- pancreatic juices (strong enzymes) enter duodenum to read down fats, carbs and proteins
- duodenum, jejunum, ileum role
- 2-4 hours for food to pass through
When referring to the small intestines in the GI tract, what is the organ and what is the accessory organs?
organ - small intestines
accessory - liver, gallbladder and pancreas
What does the liver do in the GI tract?
produce bile to emulsify fats, makes it easier to break down
What does the gallbladder do in the GI tract?
stores bile that is not needed
What does the pancreas do in the GI tract?
creates pancreatic juices that has enzymes in, squirts into breakdown
Identity the 3 sections of the small intestine
duodenum, jejunum, ileum
Describe bile
a yellow/green fluid containing bile acids to break down fats - ‘stomach acids’
What is the role of the duodenum and jejunum sections in the small intestine?
where the chyme is broken down
chyme = acidic fluid which passes from the stomach to the small intestine
What is the role of the ileum section in the small intestine?
absorbs water and nutrients into the blood stream
What is the role of the large intestines in the GI tract?
- food passes through another sphincter
- cecum - receives chyme from ileum
- colon - absorbs water to form faeces
- mucus helps the faeces slide through
- leaves undigested and indigestible food
- rectum - faeces stored before excreted
What is a sphincter?
Food passes through a sphincter to let food in but prevent it moving back. A sphincter is a strong ring shaped muscle.
What are the 3 sections of the large intestine?
cecum, colon, rectum
What does the cecum section of the large intestines do?
short pouch which receives chyme from ileum
acidic fluid
What does the colon section of the large intestines do?
absorbs water to form faeces
What does the rectum do within the large intestines?
where the faeces is stored before is is excreted
What is the role of the liver in the GI tract?
nutrients from food is absorbed into the blood stream and travels to the liver where food is processed then either stored or sent to other parts of the body to be used
What is the role of the liver in the GI tract?
- has 2 muscular sphincters - internal and external
- external sphincter is always tight, except with faeces in the rectum - can be controlled, you decide when you need to go etc
- the internal sphincter cannot be voluntarily controlled
What effect does progesterone have on the oesophagus during pregnancy?
- relaxation - leads to regurgitation of acid stomach contents and heartburn
- painful retrosternal sensation
- affects 30-70% of women
What changes occur to the stomach in pregnancy?
- less gastric acid secretion
- less gastric mobility and slower emptying
- increased pulping of food (nausea)
- stomach drapes loosing over fundus as pregnancy advances
What changes occur to the small intestine in pregnancy?
- progesterone relaxes, less effective
- increased transit time
- increased absorption time
- increased iron absorption
What changes occur to the large intestine in pregnancy?
- progesterone releaxes
- reduced motility
- increased water absorption - potential constipation, harder faeces
- increased sodium absorption
- flatulence is common
What percentage of women report increased appetite? Why?
50%
increased food consumption and thirst
Does changes to maternal appetite affect fetal growth or maternal metabolism?
No
What time of day is increased appetite quite common in pregnancy?
Morning
What hormone may be responsible for the increased appetite in pregnancy?
Leptin
Explain the hormone leptin in relation to increased appetite
Leptin is the hormone of energy, made by adipose cells to help regulate energy balance by inhibiting hunger.
Leptin typically suppresses food intake, but in pregnancy there’s evidence of hormonally induced leptin resistance, hence leptin levels increase.
Despite raised leptin levels, food intake and fat deposition increases
What causes women to feel sick more and less appetite in relation to body disfigurement?
physiological and anatomical changes during advancing pregnancy - upward gastric displacement and pressure from the gravid uterus occurs
What do oestrogen and progesterone do to the maternal appetite?
oestrogen suppresses the appetite, progesterone stimulates appetite
What percentage of women are affected by nausea and vomiting?
50-90%
At what point in pregnancy is nausea and vomiting peak?
8-12 weeks
List 3 causes of nausea and vomiting
- rise in hCG secretion
- effects of progesterone on gastric muscle
- evolutionary
Women commonly report increased thirst in pregnancy? Why?
hCG affects hypothalamus and decreases osmotic threshold for thirst
Define ‘aversions’
a strong dislike or disinclination. marked preferences or aversions are common in pregnancy
Why do pregnant women have cravings for highly flavoured food?
dulled taste buds
List some commonly reported aversions in pregnancy
coffee, tea, alcohol, meat, fried foots, eggs, cigarettes
Define ‘pica’
persistent craving anf compulsive consumption of non nutritious substance
Define ‘ptyalism’
excessive saliva
Ptyalism is a change to the oral cavity in pregnancy. Why?
due to influence of progesterone and/or hCG which increases saliva viscosity
experienced as a bad taste in the mouth, swallowing the excessive/thick saliva can induce cause and need to spit
What is the effect of oestrogen and progesterone on the gums?
- increased vascularity
- increased oedema (swelling)
- decreased ability to withstand infections
- easily irritated
- gingivitis (swelling gums)
- pregnancy epilus
What is gingivitis and what are some symptoms?
inflammation of the gums
bleeding, swelling, tenderness, pain, difficulty chewing
What percentage of maternal weight gain is accounted for by the foetus?
27%
What percentage of maternal weight gain is accounted for by the placenta, amniotic fluid and uterus?
20%
What percentage of maternal weight gain is accounted for by the breasts?
3%
What percentage of maternal weight gain is accounted for by the blood volume and extravascular fluid?
23%
What percentage of maternal weight gain is accounted for by the maternal fat stores?
27%
In what trimesters does weight gain predominantly occur?
2nd and 3rd
Approximately how much weight is gained in 1st trimester?
1.6kg
Approximately how much weight is gained per week through pregnancy?
0.4kg - 0.45kg
How do you calculate BMI?
weight (kg) divided by height (m2 or cm)
BMI normal adult range =
18.5-24.9
BMI overweight =
25.0-29.9
BMI class 1 obese =
30.0-34.9
BMI class 2 obese =
35.0-39.9
BMI class 3 morbidly obese =
over 40.0
BMI super obese =
over 50.0
BMI underweight =
less than 18.5