Consequences Of Fluid Loss From The GI Tract

Question 1

How can water be lost from the body?

Answer 1

Defecation, vomiting, urination, ventilation, sweating, mensturation

Question 2

How can you gain water?

Answer 2

Drinking

Metabolic water

Question 3

What is the definition of diarrhoea?

Answer 3

Increased frequency (>3 unformed stools in 24 hours) of increased volume and fluidity of faeces

Question 4

What does diarrhoea occur as a result of?

Answer 4

Failure of water absorption, increased secretion of water or both

Question 5

What causes osmotic diarrhoea?

Answer 5

Decreased absorption of electrolytes and nutrients

Question 6

What is the treatment of osmotic diarrhoea?

Answer 6

Electrolytes and water

Question 7

What are the symptoms of disaccharidase deficiency?

Answer 7

Bloating, nausea and watery diarrhoea

Question 8

What is the treatment for disaccharidase deficiency diarrhoea?

Answer 8

Glucose

Question 9

What is disaccharidase deficiency diarrhoea caused by?

Answer 9

Drug induced malabsorption of galactose

Question 10

What is deranged motility diarrhoea?

Answer 10

Increased rate or flow of intestinal contents

Question 11

What does increased rate or flow of intestinal contents cause?

Answer 11

Lack of absorption

Question 12

What causes secretory diarrhoea?

Answer 12

Abnormal increase in secretions of GIT

Question 13

How does secretory diarrhoea work?

Answer 13

ACh, substance P, 5-HT and neurotensin act via increased calcium ion concentration to increase rate of intestinal secretion

Question 14

What is secretory diarrhoea caused by?

Answer 14

excessive laxative use, defects in digestion and absorption and infections

Question 15

How do infections cause secretory diarrhoea?

Answer 15

Enterotoxin stimulates adenylate cyclase -> increased cAMP -> sodium and chloride ions and water loss

Question 16

What are the treatments for secretory diarrhoea?

Answer 16

Water, electrolytes and glucose

Question 17

What two parasites can cause diarrhoea?

Answer 17

Entamoeba histolytica and giardia

Question 18

What does enterotoxin stimulate?

Answer 18

Adenylate cyclase -> inc cAMP -> sodium and chloride ions and water loss

Question 19

What are the symptoms of amoebic dysentery?

Answer 19

Gradual onset anorexia/ headache

Question 20

What do you treat entamoeba histolytica with?

Answer 20

Metronidazole

Question 21

What are the symptoms of giardia?

Answer 21

Steatorrhoea and abdominal pain

Question 22

What does the giardia parasite cause?

Answer 22

Maldigestion and malabsorption of lipids, CHOs, vit A, B12 and folic acid

Question 23

What do you treat giardia caused diarrhoea with?

Answer 23

Metronidazole or tinidazole

Question 24

What is dysentery?

Answer 24

Painful, bloody, low volume diarrhoea

Question 25

What are the causes of bloody diarrhoea?

Answer 25

Chronic disease Ulcerative colitis Neoplasm

Question 26

What are the major consequences of severe diarrhoea?

Answer 26

Decreased blood volume, metabolic acidosis / alkalosis

Question 27

What are the consequences of excessive vomiting?

Answer 27

Increased salt and water loss, severe dehydration, circulatory problems, metabolic alkalosis, death

Question 28

Why does excessive vomiting cause metabolic alkalosis?

Answer 28

Loss of gastric acid

Question 29

What is lost in vomit?

Answer 29

Food, mucus with Na+ K+ Cl- and HCO3-, gastric acid, upper intestinal contents (inc bile), blood

Question 30

What are the consequences of fluid loss from the GI tract?

Answer 30

Hypovolaemia, Haemoconcentration, dehydration, ionic imbalances and poor perfusion of tissues

Question 31

What are the consequences of hypovolaemia?

Answer 31

Decreased venous return, arterial hypotension, myocardial dysfunction due to increased myocardial O2 demand

Question 32

What does increased anaerobic metabolism lead to?

Answer 32

Acidosis

Question 33

What does acidosis and myocardial dysfunction lead to?

Answer 33

Multi-organ failure

Question 34

What are the physiological responses to diarrhoea?

Answer 34

Decreased plasma volume -> decreased venous pressure -> increased renal sympathetic nerve activity

Question 35

What happens as a cause of the increased activity of renal sympathetic nerves?

Answer 35

Constriction of renal arterioles-> net glomerular filtration pressure -> decreased GFR -> decreased sodium and water secretion

Question 36

What does severe sweating lead to?

Answer 36

Loss of hyperosmotic salt solution-> decreased plasma volume or increased plasma osmolarity

Question 37

What does increased plasma osmolarity lead to?

Answer 37

Increased vasopressin -> decreased water excretion

Question 38

What does decreased plasma volume lead to?

Answer 38

Either decreased GFR or increased aldosterone -> decreased sodium excretion

Question 39

What are the steps in the RAAS cascade?

Answer 39

Dec plasma volume -> arterial pressure -> inc renin secretion -> inc plasma renin -> inc plasma angiotensin II -> inc aldosterone secretion

Question 40

What 3 things lead to thirst?

Answer 40

Decreased plasma volume, increased plasma osmolarity, dry mouth or throat

Question 41

What receptors does decreased plasma volume stimulate?

Answer 41

Baroreceptors

Question 42

What receptors do increased plasma osmolarity stimulate?

Answer 42

Osmoreceptors

Question 43

What regulates water loss?

Answer 43

Vasopressin (AKA ADH)

Question 44

What does ADH do?

Answer 44

Stimulates thirst mechanism and activates the V2 receptor on the renal collecting ducts

Question 45

What does the V2 receptor on renal collecting ducts do?

Answer 45

Inserts aquaporin-2 in the kidney collecting duct, which increases the water permeability of collecting ducts

Question 46

What are the consequences of dehydration?

Answer 46

Nausea, headache, irrationality, cramps, temperature, dizziness

Question 47

What are the effects of dehydration?

Answer 47

Imbalance of bloodstream electrolytes (decrease NaCl and potassium, increased calcium)

Question 48

What is hypercalcaemia?

Answer 48

Increased calcium concentration

Question 49

What does hypercalcaemia increase the risk of?

Answer 49

Kidney stones, kidney failure and arrhythmia

Question 50

What are the symptoms of hypercalcaemia?

Answer 50

Nausea, vomiting, loss of appetite, constipation, abdominal pain, excessive thirst, fatigue, lethargy, joint pain, confusion