1. The Digestive System and Nutrition

2. Nutrition photosynthesis Autotroph Herbivores Carnivores Heterotroph
Autotrophs – makes their own food
Heterotroph –need to obtain food from environment
Omnivores

5. DIGESTIVE SYSTEM Mouth Esophagus –long tube connecting mouth with
2 main functions:
Digesting and absorbing nutrients
Protecting from microbes
Mouth
-mechanical digestion (mastication) = teeth, tongue
-chemical digestion = saliva (amylase)
Uvula – prevents food entering the nose
Esophagus –long tube connecting mouth with
stomach
Tongue – strongest muscle in body
Saliva : Amylase =starch into maltose. Lysozyme = damages bacterial cell wall. An average person produces 25,000l in a lifetime (enough to fill 2 swimming pools)
An average person swallows 295 times while eating dinner
Incidentally, chewing is hard work and expends a lot of energy. Scientists have calculated that chewing gum increases energy consumption by 20%, by chewing calorie-free gum during waking hours and not changing any other aspect of energy balance, a person should lose about 5 kg of fat per year.
Alexander Fleming discovered lysozyme during a deliberate search for medical antibiotics. Over a period of years, he added everything that he could think of to bacterial cultures, looking for anything that would slow their growth. He discovered lysozyme by chance. One day, when he had a cold, he added a drop of mucus to the culture and, much to his surprise, it killed the bacteria. He had discovered one of our own natural defenses against infection. Unfortunately, lysozyme is a large molecule that is not particularly useful as a drug. It can be applied topically, but cannot rid the entire body of disease, because it is too large to travel between cells. Fortunately, Fleming continued his search, finding a true antibiotic drug five years later: penicillin.
Epiglottis – safety hatch. A flap of cartilage prevents food from entering the trachea (wind
pipe)

6. -transfers food to stomach by peristalsis
Esophagus
-transfers food to stomach by peristalsis
Cardiac sphincter
-opens to allow food esophagus stomach
-heartburn –acid escapes stomach esophagus
Peristalsis - A series of normal coordinated, rhythmic muscle contractions that occurs automatically to move food through the digestive
Tract (oesophagus, small intestine, large intestine) , urine from the kidneys through the ureters into the bladder, and bile from the gall bladder into the duodenum.

7. 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
What causes our stomach to growl?
Stomach growling occurs when the stomach receives signals from your brain to begin digestion but the stomach is empty. Your brain might sense you're running low on energy (glucose) or even seeing or smelling something you want to eat can get things going. The motion of the stomach muscles begins, but the organ is hollow. The movement of the muscles mixing the acids of the stomach in the hollow space of the stomach produces vibrations we hear as growling, or rumbling, or gurgling.

8. Stomach Epithelium Mucous – goblet cells --
prevents self-digestion
Enzymes (pepsinogen) – chief cells
Activated to pepsin by HCl
Converts proteins peptides
Acid (HCl) – parietal cells
pH 1-2
Kills bacteria
Loosens fibrous foods
Activates pepsinogen
Denatures salivary amylase
Hormone (gastrin) – G cells
Controls gastric motility and
acid secretion
Ulcers (stomach, duodenum) –
peptic ulcers. Most commonly
caused by H. pylori
Mucous – lubricates food. Prevents stomach self-digesting. Prevents attachment of bacteria
HCl – stomach pH = 1-2. Kills bacteria, helps breakdown food, activales pepsinogen, deactivates amylase
Pepsinogen (pro-enzyme) – activated by HCl – pepsin (this prevents the enzyme from digesting cells that produce it). Breaks proteins down into peptides
Stomach epithelial cells are some of the fastest growing cells in the body, typically replacing themselves
about every 3 days

9. ULCERS http://www.youtube.com/watch?v=9-aVA8mz4e4&feature=related
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

11. ULCERS TREATMENTS FACTORS SUCH AS: Smoking acid-reducing medicines
Caffeine
Alcohol
Stress
can all contribute to the formation of ulcers
TREATMENTS
acid-reducing medicines
antibiotics
lifestyle adjustments (lower stress levels)

14. 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
NaHCO3 = neutralises acid
Once trypsinogen and chymotrypsinogen are released into the lumen of the small intestine, they must be converted into their active forms in order to digest proteins. Trypsinogen is activated by the enzyme enterokinase, which is embedded in the intestinal mucosa.
Once trypsin is formed it activates chymotrypsinogen, as well as additional molecules of trypsinogen. The net result is a rather explosive appearance of active protease once the pancreatic secretions reach the small intestine. Trypsin and chymotrypsin digest proteins into peptides and peptides into smaller peptides, but they cannot digest proteins and peptides to single amino acids.
Insulin
Glucagon
Emulsification = breaks fats and oils into tiny droplets, increasing surface area to aid digestion
Salad dressing

15. 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)

16. Liver Weighs about 1.5kg Holds about 13% of total blood
Liver cell = hepatocyte
Unique ability to regenerate – average life = 150 days
Right lobe
Left lobe
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
Blood rich in
food from ileum
Aas can’t be stored – become toxic and hence aas not needed are broken down by liver in a process known as deamination

17. LIVER DISEASES HEPATITIS SYMPTOMS TREATMENTS
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)
SYMPTOMS
Fever
Appetite loss, nausea
Abdominal pain
Jaundice (yellow skin, eyeballs)
TREATMENTS
Drugs
Vaccination (prevention)

18. HEPATITIS http://www.youtube.com/watch?v=U5gDwag1L-w&feature=related

21. CIRRHOSIS WHAT IS IT? CAUSES:
Scar tissue and fat replace healthy liver tissue – making the liver virtually useless
CAUSES:
Alcoholism
Hepatitis C
TREATMENT:
Liver transplant

23. 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

24. GALLSTONES con’t CAUSES: Obesity Alcohol intake Heredity TREATMENT:
Medications
Ultrasound (disintegrate the stones)
Surgery to remove gallbladder

26. 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
The ileum is 4m long. It produces enzymes that are responsible for the final stages of digestion. The main job of the ileum is absorption and the inside surface of the ileum is also covered in villi, which increase the surface area which can absorb nutrients, such as vitamins, amino acids and simple sugars. These nutrients are absorbed into the bloodstream and distributed around the body. By the time the food leaves the ileum, most of the useful nutrients have been absorbed.

27. 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 the start of the lg I
Appendix
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)

28. 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
Probiotics are live micro-organisms that, when consumed in adequate amounts, confer a health benefit to the host.   They are the 'good', 'friendly' or 'beneficial' bacteria which when ingested act to maintain a healthy gastrointestinal (GI) tract and help to fight illness and disease. These good health-promoting bacteria can provide a protective effect against potentially harmful bacteria, known as pathogens , which also reside in the GI tract.   The human GI tract is inhabited by two kilograms of bacteria, known as commensals, representing over 400 different species.   These bacteria are critical for normal development of the intestine and for defence against infections and are vital for our health.   Bacteria in the gut are known to:
Aid digestion and break down toxins
Produce vitamins B12 and K
Stimulate the immune system

29. INFLAMMATORY BOWEL DISEASE
CROHN’S DISEASE – inflammation of the intestinal lining (usually the ileum)
COLITIS - inflammation and ulceration of the lining of the colon

30. WHAT’S THE DIFFERENCE BETWEEN CROHN’S & COLITIS?
CROHN’S DISEASE
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
COLITIS
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

31. CROHN’S DISEASE SYMPTOMS: TREATMENT
Abdominal pain
Cramping
Diarrhea
Rectal bleeding
Weight loss
Skin problems
TREATMENT
Drugs to control inflammation
Dietary adjustments

33. COLITIS SYMPTOMS: TREATMENTS:
Diarrhea
Abdominal cramps
Weight loss
TREATMENTS:
Drugs to reduce inflammation
Surgery

35. OBESITY

36. OBESITY
CAUSES??
CURES??

37. OBESITY INFO TREATMENT: CAUSES: Lifestyle changes – diet/exercise
Surgery – stomach stapling, liposuction,etc
>50% of Canadians are classified as either overweight or obese
CAUSES:
Lifestyle
Genetics
Hormones
Social factors
Biological?

38. OBESITY PREVENTION? REGULAR EXERCISE HEALTHY DIET

41. HOW IS OBESITY DEFINED? – BY USING A BMI (BODY MASS INDEX)

42. ANOREXIA NERVOSA
An eating disorder characterized by an intense fear of gaining weight
Patients will starve themselves
Their weight is typically <85% of “normal” body weight

43. ANOREXIA con’t CAUSES: Distorted self-image Low self-esteem
Psychological difficulties
TREATMENT:
Stabilize life-threatening symptoms (low BP, irregular heart beat, etc)
Psychological therapy

45. The Immune System
                                                              

46. The Immune System General Defence System (innate)
Defends body against pathogens
Can distinguish between self and non-self
General Defence System (innate)
Specific Defence System (adaptive)
Non-specific = acts against all pathogens
Rapid
1. First line of general defence
Skin = barrier. Sweat (acidic pH)
Clotting = also helps protect skin
Lysozyme = enzyme in saliva, sweat, tears. Attacks bacterial cell walls
Mucous (respiratory, digestive, urinary & reproductive tracts) = traps pathogens
Cilia = little hairs that help clear mucous (and pathogens) from respiratory tract
Alimentary canal = lysozyme in saliva, stomach HCl kills many pathogens, specialised immune areas in the GI tract, very high turnover of epithelial cells, antibodies

47. 2. Second line of general defence
Phagocytic white blood cells (leukocytes) = destroy pathogens that enter
Complement
Inflammation
Neutrophils – mulitlobed nucleus. Granules contain peroxidases, defensins
Macrophages (tissue bound) – “Big eater” large cells with a horsesheo shaped nucleus
Monocytes (blood) -
Phagocytes – (Phago= eat; cyte=cell)
attracted to a site of infection (chemotaxis) by chemicals released by injured cells
Three types – neutrophils (short lived),
monocytes (short-lived..in blood) and macrophages (long-lived..in tissue)

48. Immune organs Macrophages – very large white cells that can move
around body, or remain in certain tissues. Long lived,
act as scavengers

49. 2. Second line of general defence cont.
Complement
set of 30 proteins found in plasma that are activated by
infection
complicated chain reaction that leads to the bursting of
viruses and bacteria
made in the liver
Interferons
set of proteins produced by virally infected cells cells to limit the spread of viral
infections, by inducing a state of resistance in healthy cells.
induced by viruses, bacteria and other signals from the immune system
Histamine - When released from mast cells , histamine causes vasodilation and an increase in permeability of blood vessel walls. These effects, in turn cause the familiar symptoms of allergy including a runny nose and watering eyes. When released in the lungs, histamine causes the airways to swell shut in an attempt to close the door on offending allergens and keep them out. Unfortunately, the ultimate result of this response is the wheezing and difficulty in breathing seen in people with asthma - an occasionally deadly allergic complication which kills an estimated 4000 Americans yearly. See also : Antihistamine .
Inflammation
infected cells (mast cells) release histamine, which is a vasodilator. This causes
localised swelling, redness, heat, pain. Can also cause high temperature.
brings white cells to the area of infection
Anti-histamines

50. Specific Defence System (Adaptive Immune System)
Antigens – foreign molecules that
generate antibody production
Antibodies (immunoglogulins) – proteins
produced by lymphocytes in response
to antigens
Monocytes – develop into macrophages which phagocytose foreign particles (antigens)
Lymphocytes -
Antigen = antibody generating. Eg. Viral coat proteins, bacterial cell wall components, pollen, foreign blood cells
A lymphocyte is a type of white blood cell involved in the human body's immune system. There are two broad categories of lymphocytes, namely T cells and B cells. Lymphocytes play an important and integral part of the body's defenses.
T-cells are responsible for cell mediated immunity whereas B-cells are responsible for humoral immunity (relating to antibodies). T-cells are named such because these lymphocytes mature in the thymus and B-cells mature in bone marrow.
In the presence of an antigen, B-cells become much more metabolically active and transform into Plasma cells. Plasma cells are large lymphocytes with a large nuclear to cytoplasmic ratio and are the form of B-cell lymphocytes that produce antibodies. Azurophilic granules are often present with an increase in cytoplasm.
Microscopically, in a Wright's stained peripheral blood smear, a normal lymphocyte has a large, dark-staining nucleus with little to no basophyllic cytoplasm. In normal situations, the coarse, dense nucleus of a lymphocyte is approximately the same size as a red blood cell (about 7 micrometres in diameter). Some lymphocytes show a clear perinuclear zone (or halo) around the nucleus or could exhibit a small clear zone to one side of the nucleus.
It is impossible to distinguish between T-cells and B-cells in a peripheral blood smear. Normally, flow cytometry testing is used for specific lymphocyte population counts. When one must specifically determine the percentage of lymphocytes that produce a particular secretion (say, a specific antibody or cytokine), the ELISPOT technique can be used instead.
The Human Immunodeficiency Virus hijacks and destroys T-cell lymphocytes (specifically, CD4 lymphocytes). Without this key defense, the body is susceptible to opportunistic diseases that otherwise would not kill healthy people.
A lymphocyte count is part of a peripheral complete blood cell count and is expressed as percentage of lymphocytes to total white blood cells counted. An increase in lymphocytes is usually a sign of a viral infection (rarely, leukemias are found through an abnormally raised lymphocyte count in an otherwise normal person). A general increase in the number of lymphocytes is known as lymphocytosis whereas a decrease is lymphocytopenia.

51. Lymphocytes
B lymphocytes – mature in Bone marrow lymphatic tissue, especially spleen and lymph nodes
T lymphocytes – mature in the Thymus
Large nucleus

52. B-lymphocytes B lymphocytes make antibodies = immunoglobulins
Can bind to pathogens and prevent them from infecting cells. Pathogens are then destroyed by phagocytes
B-lymphocytes
B lymphocytes make antibodies = immunoglobulins
Can inactivate pathogens by causing them to clump together
Can trigger the complement system, resulting in pathogens being burst
B cells (along with T cells) come in contact with antigen. They are stimulated (by T cells) to produce many clones, plasma cells, which make antibodies.
1000s of different B cells, each recognises a different antigen on the surface of a macrophage. Each antigen stimulates production of a single specific antibody
Each B cell is programmed to make one specific antibody. For example, one B cell will make an antibody that blocks a virus that causes the common cold, while another produces antibody that zeros in on a bacterium that causes pneumonia.
When a B cell encounters its triggering antigen(along with collaborating T cells and accessory cells), it gives rise to many large plasma cells. Every plasma cell is essentially a factory for producing antibody. Each of the plasma cells descended from a given B cell (which are all members of the same family, or clone) manufactures millions of identical antibody molecules and pours them into the bloodstream. Plasma cells only live a few days but can produce 2000 antibodies per second while alive. Some plasma cells live longer (memory B cells) – which allow for a much faster reaction to an infection the second time.
A given antibody matches an antigen much as a key matches a lock. The fit varies: sometimes it is very precise, while at other times it is little better than that of a skeleton key. To some degree, however, the antibody interlocks with the antigen and thereby marks it for destruction.
Memory B cells – faster, more sensitive reaction
= secondary response

53. How B-cells work… Pathogen (e.g. bacteria, virus) B-cells Plasma cells
Macrophage
B-cells
Each recognise
a different antigen. The correct one develops into…
Plasma cells
Clones of the correct B-cell, which produce antibodies
Macrophage
Phagocytoses pathogen and displays antigens on surface
1st meeting a pathogen, this process takes days
Memory B cell= subesquent meetings, takes about 5 days

54. T-lymphocytes
Mature in Thymus, which is most active just before and after birth.
The thymus starts to shrink during puberty.
Helper T-Cells
Recognise antigens on surface of leukocytes, especially macrophages
Enlagre and form a clone of T-helper cells
Secrete interferon and cytokines which stimulate B-cells and stimulate killer -cells
Can be infected by HIV
Killer T-Cells
Also called cytotoxic
Destroy abnormal body cells, e.g. virus infected or cancer cells
Stimulated by cytokines (THcells)
Release perforin, which forms pores in target cells. This allows water and ions in = lysis
Suppressor T-Cells
Control the immune system when the antigen /pathogen has
been destroyed
Only recently discovered so
little is known about them
Memory T-Cells
Can survive a long time and give lifelong immunity from infection
Can stimulate memory B-cells to produce antibodies
Can trigger production of killer T cells
Interferon – interferes with virus replication. The protein interferon, produced by animal cells when they are invaded by viruses, is released into the bloodstream or intercellular fluid to induce healthy cells to manufacture an enzyme that counters the infection. Interferon is therefore considered a potential medical resource as a BIOPHARMACEUTICAL.
Cytotoxic – Greek – kytos = hollow, Toxikon = poison

55. Duration of immunity Immune disorders
Memory B-cells circulate for a long time. If the same pathogen infects the body again, these B-cells can produce large amounts of specific antibody very quickly. This is why you usually don’t suffer from the same infection twice.
Memory T-cells survive a long time and trigger an immune response
Immune disorders
Sometimes the body produces antibodies against its own tissues e.g. autoimmune diseases e.g. rhumatoid arthritis, Crohn’s disease, SCID (bubble boy disease)
asthma
Edward Jenner
Used cowpox to vaccinate against small pox
Allergies occur when the body reacts to materials which should not be antigenic e.g. peanuts
Tumours – in most cases the body recognises tumours as being bad, because they express abnormal molecules on the cell surface. However sometimes the body doesn’t notice and cancers can develop

56. Induced Immunity Active immunity
Production of a person’s own antibodies. Long lasting
Passive immunity
An individual is given antibodies by another
Short-term resistance (weeks- 6months)
Natural Passive
Baby in utero (placenta)
Breast-fed babies
Natural Active
When pathogen enters body in the normal way, we make antibodies
Edward Jenner
Artificial Active
Vaccination – usually contains a safe antigen from the pathogen. Person makes antibodies without becoming ill
Artificial Passive
Gamma globulin injection
Extremely fast, but short lived (e.g. snake venom)
Gamma globulin – from animals

57. Career in Science ? BSc – Biochemistry in UCC
PhD – Cell biology/virology in Heidelberg, Germany (met my French husband)
Post-doc – Cell biology in San Francisco, USA
Industry – Elan
Now – juggle 2 jobs:
General Manager of the Alimentary Pharmabiotic Centre

58. Why Science? What can you do…?
Interesting and challenging work – no two days the same
Interesting people – APC has 19 nationalities
International qualification
Travel
Satisfaction
Career, not just a job
Pharmaceutical
Medical Devices
Biotechnology
Healthcare
Food & Drink
Environmental
Health & Safety
Electronics
Academia
Business
What can you do…?