gastrointestinal system

Question 1

dentition + age

Answer 1

survey looking at proportion of people with at least 21 teeth
from born between 1945 and 1925 - lowest proportion for those born before 1925
before NHS so had a lack of dental support throughout their lifetime

Question 2

effect of dentition

Answer 2

on ability to eat various types of food
- nutrient dense foods are harder to eat compared to unhealthier (processed) foods
- harder to eat foods with more vitamins and minerals as you age which is important as they have lower caloric intake

Question 3

mouth + ageing

Answer 3

olfactory receptors lost by ~10% per decade
taste buds- reduced number and sensitivity
reduced sense of taste- particularly salty and umami

Question 4

tongue/jaw + ageing

Answer 4

reduced muscular strength
may lead to difficulties chewing

Question 5

salivary glands and ageing

Answer 5

slight reduction in salivary flow
more marked in some medical conditions eg parkinsons
maintained enzyme concentrations eg amylase

Question 6

oesophagus and ageing

Answer 6

neurodegeneration
reduced muscular strength- reduced motility

Question 7

stomach histology

Answer 7

chief cells- secrete pepsinogen (break down proteins)
parietal cells- secrete inrtrinsic factor and HCl
G cells- secrete gastrin which stimulates chief and parietal cells- increasing motility

Question 8

stomach + ageing

Answer 8

some neurodegeneration in stomach and intestines - reduced gastric emptying
reduced production of somatostatin (inhibits gastrin) from plyoric glands- sustained producion of gastric acid- contributes to higher prevalence of gastro oesophogal reflux
little change in function in healthy adults

Question 8

age related pathologies affecting stomach

Answer 8

atrophic gastritis
more prevalent with age
may be related to non steroidal anti inflammatory drug use (ibruprofen)
atrophy of parietal and chief cells (replaced ny fibrous tissue)- reduced secretion of HCl and intrinsic factor from parietal cells, less pepsin from chief cells
pepsin is activated by being in an acidic environment- less HCL acid= less pepsin
elevates insulin- inhibits production of ghrelin- appetitie hormine produced by stomach- explains why people feel less hungry as they get older

Question 9

pancreas + ageing

Answer 9

reduced lipase, amylase and trypsin production

Question 10

small intestine + ageing

Answer 10

structure- maintained number and height of villi
higher prod of CCK so reduced gastric emptying and increasrd satiety
reduced contractile force from smooth muscles- longer transit time

Question 11

SI + ageing

Answer 11

effects on absorption
- AA and carb absorption maintained- lactase prod may be lower= lactose intolerance
- reduced absorption of calcium particularly in postmenopausal women
- gastritis- redcued absorption of b12 and iron
- redcued lipase production= reduced fat absorption

Question 12

large intestine

Answer 12

atrophy of smooth muscle and reduction in enteric nervous system function= increased transite time
increased fibre number and crosslinking= increased prevalence of diverticulosis (gut wall can become stretched, where pockets of faecal matter may stay)

Question 13

gut microbiota and health

Answer 13

microbiota- community of microorganisms
microbiome- their collective genome
microbiota diversity- measure of number of species and distribution, low diversity associated with obesity, diabetes etc
probiotics- live bacteria/yeasts
prebiotic- substrate selectively used by microorganism conferring health eg fermentable dietary fibre

Question 14

gut microbiota and age

Answer 14

foetus- usually sterile
baby- breast feeding introduced favourable strains, bottle fed more diverse
child- increase in diversity
adults- peak diversity, composition depends upon long term diet
can be modified with dietary modification
older- decline in diversity, may be due to lower fibre intake

Question 15

liver histology

Answer 15

~100,000 hexagonal lobules- functional unit of liver (1mm diameter)
portal areas contain: branch of hepatic portal vein, branch of hepatic artery proper, branch of bile duct
blood flows past hepatocytes- absorb solutes + secrete proteins
drains into - sinusoids to central vein
bile ductules>bile ducts

Question 16

liver + ageing (structure)

Answer 16

liver has a large reserve so is maintained a lot even with older age
structure
- mass reduced
- number of hepatocytes declines- reduction in ER and enzyme activity
- lipofuscin accumalation

Question 17

liver function

Answer 17

changes with ageing
- largely retained
- pseudo capillarisation- reduction in fenestration of sinusoidal endothelial cells
- reduced chlyomicron remnant uptake. reduced blood flow (up to 40%)
- reduced drug clearance
- pseudo capillarisation- more like normal capillaries

Question 18

kidney- renal structure

Answer 18

changes with ageing
decline in mass, particularly cortex
increased fat infiltration and prevalence of cysts and scarring

Question 19

kidney- arterial changes

Answer 19

thickening of intima
loss in vessel number and cross section, vessels more tortuous
decline in renal blood flow- reduced glomerular filtration rate- reduced capacity clearance and reabsorption
increased prevalence of glomerulosclerosis - related to hypertension (scarring of glomerular)

Question 20

kidney- changes in function

Answer 20

proximal tubule/interstitial
- site of reabsorption of most solutes
- maximal rate of reabsorption declines
- consequences include reduced clearance of insulin and sodiim

loop of henle
- reduced ability to reabsorb ions eg sodium
- reduced ability to concentrate and dilute urine

renin-angiotensin system
- blood pressure and fluid balance regulation
- activity declines with age

Question 21

consequences of age related GI change

Answer 21

bigger changes due to disease rather than ageing itself
- upper GI tract- changes may affect food choice
- intestinal absorption- absorption of macronutrients maintainedm reduced ability to absorb b12,6, iron and calcium
- metabolism- decline in gut micorbiota diversity, drugs may be metabolised or cleared more slowly, compromised ability to mainatin fluid and electrolyte balance

Question 22

physical changes with ageing and disease

Answer 22

reduced efficiency of GI tract leads to malabsorption and reduced bioavailabiluty of micronutrients
periodontal disease and poorly fitted denture can also result in avoidance of foods such as meat
degeneration of brush border cells of SI can limit production of lactatse promoting lactose intolderance
atrophic gastritis reduced ability to absorbb12 and iron
sense of taste and smell-decline with age leading to impaired appetite
decline with age leading to impaired appetite

Question 23

physical infirmity and malnutrition

Answer 23

stems from disability or disease
- cancer, CVD, renal disease and diabetes are comorbidities of malnutrition in the elderly
- increased nutrient requirements for energy, protein and micronutrients
- physical immobility and increased dependence upon carers
- reduced ability to shop, cook and self feed.