3. Gastrointestinal (GI) Tract
• A continuous, hollow coiled tube that
digests food, breaks it down, and absorbs
the fragments through its lining into the
blood
16. Stomach Functions
Slide
Acts as a storage tank for food
Site of food breakdown
Chemical breakdown of protein begins
Delivers chyme (processed food) to the
small intestine
Produces 2-3L/day of gastric juice (HCl,
enzymes, & mucus)
Regulated by neural & hormonal factors
17. Diseases and Disorders
• Heartburn – occurs when the cardio-esophageal
sphincter fails to close tightly and gastric juice
backs up into the esophagus
• Hiatal hernia – superior part of the stomach
protrudes above the diaphragm allowing juices to
go into the esopahgus
• Vomiting – reverse movement of food, brought
about by a signal from the medulla
18. • It takes 4 hours for the stomach
to empty after a well-balanced
meal and 6 hours for a fatty
meal
35. Structures of the Large Intestine
Slide
Ileocecal valve – btwn small & large
intestine
Cecum – saclike 1st part of the large
intestine
Appendix
Accumulation of lymphatic tissue that
sometimes becomes inflamed
(appendicitis)
Hangs from the cecum
40. Diseases and Disorders
• Diarrhea – results when water is not
sufficiently absorbed by large intestine (can
be due to bacteria)
• Constipation – results when too much water
is absorbed by the large intestine
57. Metabolism
• Metabolism – chemical reactions that are
necessary to maintain life
– Catabolism – substances are broken down,
energy released and captured to make ATP
– Anabolism – small molecules come together to
form larger molecules
58. How to maintain blood glucose
(sugar) levels…
• Blood circulates through the liver and
glucose is removed. If the body has an
abundance, glucose is made into gycogen.
This is called glycogenesis.
• If the body is low on sugar, the liver will
break down the glycogen into sugar. This is
called glycogenolysis.
59. Carbohydrate metabolism
• Cellular respiration – glucose is broken
down, releasing chemical energy to form
ATP
• Glucose + O2 = CO2 + H20 + ATP
• If too much sugar is in the blood, it si
converted to FAT!
60. Fat metabolism
• Most of it occurs in the liver
• Fat is broken down into acetic acid. Then it
is oxidized and CO2, H2O, and ATP are
formed.
• This occurs when there are low amounts of
sugar in the blood.
61. Protein metabolism
• Amino acids (make up proteins) are used to
make ATP only when proteins are over
abundant or carbs. and fats are not
available.
• Amino acids are oxidized and ammonia
(NH3) is given off (secreted). The rest if the
amino acids enter the citric acid cycle.
64. Diseases and Disorders
• Gallstones occur when bile is stored for too
long and fat crystallizes
• Jaundice – bile enters the blood stream and
tissues become yellow
72. Nutrition cont.
• Vitamins: need a balanced diet to obtain
essential vitamins
• Most fxn as a coenzyme (act w/out an enzyme to
complete a rxn)
• Mineral – body requires 7 minerals (Ca, P, K, S,
Na, Cl, Mg)
• Water
73. What nutrients do for the body
• Carbohydrates – broken down to form ATP
• Lipids – build cell membranes, make
myelin sheath and insulates the body
• Proteins – major structure for building cells
75. Metabolic rate
• Basal metabolic rate – the amount of heat
produced by the body per unit of time while at
rest. This represents the energy supply a person
needs to perform essential life activities.
• Ex. 154lb adult has a BMR of 60-72 kcal/hr
• Total metabolic rate – total amount of kilocalories
the body must consume to fuel all ongoing
activities
76. Factors that influence BMR
• Surface area, gender, age, and thyroid
• Younger people have a high BMR
• Smaller people have a lower BMR
• Hyperthyroidism – excessive metabolic rate
= thin
• Hypothyroidism – slower metabolic rate =
obese
77. Diseases and Disorders
• Frostbite – when the body is exposed to low
temperatures. Capillaries constrict to keep
blood deeper for the internal organs.
• Shivering – occurs when internal body
becomes too cold; this produces heat
• Hypothermia – extremely low body temp.
This results from prolonged exposure to the
cold; vital signs decrease
78. Diseases and Disorders
• If the body is hot, capillaries become flushed with
warm blood, releasing heat. Sweating will occur.
Heat stroke or heat exhaustion can occur.
• Cleft palate – palate does not form properly;
deformities of mouth, nose, and lips
• Cystic fibrosis – excessive mucus impairs activity
of pancreas. Fat and fat-soluble vit. are not
digested
79. Diseases and Disorders
• PKU – inability to use amino acids in food;
can cause brain damage and mental
retardation
• Gastroenteritis – inflammation of the
gastrointestinal tract; can be caused by
contaminated food
80. Diseases and Disorders
• Appendicitis – inflammation of the
appendix
• Ulcer – lesion or erosion of mucus
membrane, exposed to secretions of the
stomach