Download BIO 20 DIGESTIVE SYSTEM

Digestive
System
Disorders
http://apc.ucc.ie
Esophagus
-transfers food to stomach by peristalsis
Cardiac sphincter
-opens to allow food esophagus stomach
-heartburn –acid escapes stomach esophagus
http://library.thinkquest.org/11226/main/c03txt.htm
Stomach
Short term storage reservoir (1L for up to 4h)
Digestion = chemical (HCl and enzymes) - proteins
= mechanical - liquefication of food
Slowly releases food into intestine
chyme
Cardiac sphincter
Pyloric sphincter
http://35.9.122.184/images/41-AnimalNutrition/41-16-Duodenum-L.gif
Stomach Epithelium
Mucous – goblet cells -- prevents self-digestion
Enzymes (pepsinogen) – chief cells
Acid (HCl) – parietal cells
Activated to pepsin by HCl
Converts proteins peptides
pH 1-2
Kills bacteria
Hormone (gastrin) – G cells Loosens fibrous foods
Activates pepsinogen
Denatures salivary amylase
Controls gastric motility and
acid secretion
Stomach epithelial cells are
some of the fastest growing
cells in the body, typically
replacing themselves
about every 3 days
Ulcers (stomach, duodenum) –
peptic ulcers. Most commonly
caused by H. pylori
ULCERS
• An ulcer forms when the mucus
layer that protects the stomach
lining erodes due to the HCl in
the stomach
• An acid-resistant bacteria:
Helicobacter pylori attaches to
the stomach wall causing the
site of attachment to stop
producing mucus
http://www.youtube.com/watch?v=9-aVA8mz4e4&feature=related
http://www.youtube.com/watch?v=4bXZRgJ-1fk
http://www.youtube.com/watch?v=4bXZRgJ-1fv
ULCERS
FACTORS SUCH AS:
o Smoking
o Caffeine
o Alcohol
o Stress
can all contribute to
the formation of ulcers
TREATMENTS
o acid-reducing medicines
o antibiotics
o lifestyle adjustments
(lower stress levels)
Small Intestine
Around 6m in an adult
Food takes 1-6 h to pass through
2 main tasks = digestion, absorption
3 parts
Duodenum
Jejenum
Ileum
Duodenum = 25cm long
- the duodenum is mainly responsible for
the digestion of nutrients
Pancreas –pancreatic juice= NaHCO3, enzymes (insulin, glucagon)
pH of duodenum = 7-8
Amylase, lipase, trypsinogen, chymotrypsinogen
Liver –
bile made in liver, stored in gall bladder = Water, salts, bile salts
Neutralise HCl
Digestion and absorption of fats and fat soluble vitamins (emulsification)
Waste products eliminated by secretion into bile and elimination in feces
(e.g. bilirubin, biliverdin)
Liver
Right lobe
Left lobe
Blood rich in
food from ileum
Weighs about 1.5kg
Holds about 13% of total blood
Liver cell = hepatocyte
Unique ability to regenerate – average life = 150 days
The liver performs over 500 jobs. Some of these are:
•Makes bile (600mls/day)
•Detoxifies body (alcohol, drugs etc)
•Breaks down excess amino acids urea (deamination) kidney
•Converts glucose glycogen for storage (source of quick energy)
•Converts excess carbohydrates fat
•Stores vitamins - A, D, E and K
•Stores minerals – Fe, Cu, Zn
•Makes plasma proteins e.g. fibrinogen – blood clotting
•Makes cholesterol – needed to form many hormones
•Produces heat to warm blood
•Clears blood of particles, including bacteria
•Fights infections –half the body’s macrophages -destroy bacteria
•Produces hormones, including the sex hormones
http://www.britishlivertrust.org.uk/content/liver/about.asp
LIVER DISEASES
• HEPATITIS
• SYMPTOMS
• an inflammation of the liver
• 3 types:
• HEPATITIS A: from drinking
contaminated water
• HEPATITIS B: sexual contact
(more contagious than AIDS)
• HEPATITIS C: infected blood
(no vaccine currently)
•
•
•
•
Fever
Appetite loss, nausea
Abdominal pain
Jaundice (yellow skin, eyeballs)
• TREATMENTS
• Drugs
• Vaccination (prevention)
HEPATITIS
http://www.youtube.com/watch?v=U5gDwag1L-w&feature=related
http://www.youtube.com/watch?v=cb5rpIk6dQY
CIRRHOSIS
WHAT IS IT?
• Scar tissue and fat replace
healthy liver tissue –
making the liver virtually
useless
CAUSES:
• Alcoholism
• Hepatitis C
TREATMENT:
• Liver transplant
http://www.youtube.com/watch?v=GruK1SXhPJk&feature=related
GALLSTONES
• Cholesterol in the bile can
precipitate out and form
crystals
• The crystals grow in size
and become stuck in the
gall bladder and duct
leading to the duodenum
GALLSTONES con’t
CAUSES:
• Obesity
• Alcohol intake
• Heredity
TREATMENT:
• Medications
• Ultrasound (disintegrate
the stones)
• Surgery to remove
gallbladder
Small Intestine cont.
Jejenum – digestion/ absorption. 2.5m long
Ileum – absorption. 4m long
Walls only one cell thick
Villi, microvilli – increase surface area for absorption
Rich blood supply – capillaries absorb water and soluble nutrients (glucose, amino acids,
vitamins, minerals) and the blood carries the nutrients to the liver, which stores nutrients
and releases them as required
Lacteal – contains lymph. Fatty acids and glycerol are absorbed by the epithelial cells
where they reform into fats. They become coated in protein (chylomicrons) and pass into
the lymph in the lacteals. It takes around 18h for lymph to rejoin the blood, the protein
coat dissolves and fats are absorbed into cells
Large Intestine
1.5m long, 6cm diameter – much
THICKER than small intestine
Food stays 10h to a few days
-More fat in diet – longer duration
-More roughage – less duration
Caecum
Appendix
the start of the lg I
Function unknown – in
herbivores they
contain bacteria that
help digest cellulose
Large intestine (also called colon)
Reabsorbs water – so waste is converted to semi-solid = feces – eliminated
Diarrhea, constipation (fibre helps stimulate peristalsis of GI tract)
Bacteria
1-2kg of bacteria in your gut = 4000 species
Bad - bacteria that can cause illness e.g. H pylori (ulcers), Salmonella, E. coli,
Listeria (food poisoning)
Good – symbiotic bacteria. These live in close harmony with the body without causing
harm, and have additional health benefits. Probiotics are live micro-organisms that,
when consumed in adequate amounts, confer a health benefit to the host.
e.g. bifidobacteria, lactobacillus (found in yogurt)
•Aid digestion
•Break down toxins
•Produce vitamins B12 and K
•Stimulate the immune system
•Help prevent growth of cancers
http://microbemagic.ucc.ie
INFLAMMATORY BOWEL DISEASE
• CROHN’S DISEASE – inflammation of
the intestinal lining (usually the ileum)
• COLITIS - inflammation and ulceration
of the lining of the colon
WHAT’S THE DIFFERENCE BETWEEN
CROHN’S & COLITIS?
• CROHN’S DISEASE
• COLITIS
• It can affect any part of
the digestive tract, but
usually only affects the
ileum
• Inflammation extends
deep into the lining of the
intestine
• Surgery not usually an
option
• It affects the colon
• The inflammation is
usually restricted to the
inner lining of the colon
only
• Surgery can be used to
remove parts or all of the
colon
CROHN’S DISEASE
• SYMPTOMS:
•
•
•
•
•
•
Abdominal pain
Cramping
Diarrhea
Rectal bleeding
Weight loss
Skin problems
• TREATMENT
•
•
Drugs to control inflammation
Dietary adjustments
http://www.youtube.com/watch?v=891vb1XyyEk
COLITIS
SYMPTOMS:
• Diarrhea
• Abdominal cramps
• Weight loss
TREATMENTS:
• Drugs to reduce inflammation
• Surgery
http://www.youtube.com/watch?v=Iypn1Jh1_xY
Celiac Disease
• Celiac disease is a medical
condition in which the absorptive
surface of the small intestine is
damaged by a substance called
gluten. This results in an inability
of the body to absorb nutrients:
protein, fat, carbohydrates,
vitamins and minerals, which are
necessary for good health.
• Although statistics are not readily
available, it is estimated that 1 in
133 persons in Canada are
affected by celiac disease.
SYMPTOMS
•
•
•
•
•
•
diarrhea
bloating, cramps
headaches
weight loss
fatigue
dermatitis herpatiformis
(an itchy, bumpy rash that
forms all over the body)
- From the Canadian Celiac Association
Celiac Disease
CAUSES
• unknown, although
genetics does play a
role
TREATMENT
• life-long elimination
of gluten from diet
• some medications can
be used to treat skin
conditions
• no cure
Normal small intestinal villi compared to
Celiac small intestinal villi
Celiac Disease
What is gluten?
• a specific protein found
in wheat, barley and rye
• in people with celiac
disease, gluten attacks
the villi of the small
intestine and breaks them
down
• Without properly
functioning villi,
nutrients can’t be
absorbed properly
What is gluten-free food?
• corn, rice, potatoes, beans
• all fruit and veggies in their
natural forms (ie not
processed)
Look for this symbol:
Celiac Disease
Treatment for Celiac Disease
OBESITY
OBESITY
• CAUSES??
• CURES??
OBESITY INFO
TREATMENT:
• >50% of Canadians are
classified as either
overweight or obese
CAUSES:
•
•
•
•
•
Lifestyle
Genetics
Hormones
Social factors
Biological?
• Lifestyle changes –
diet/exercise
• Surgery – stomach
stapling, liposuction,etc
OBESITY PREVENTION?
• HEALTHY DIET
• REGULAR EXERCISE
http://www.youtube.com/watch?
v=dLMoFST_Lmc
HOW IS OBESITY DEFINED? – BY USING A BMI
(BODY MASS INDEX)