Download The Human Body: From Food to Fuel

The Human Body:
From Food to Fuel
BIOL 103, Chapter 4
(Part 2)
Today’s Topics
• Signaling Systems: Command, Control, and
Defense
– The Hormonal System
– The Immune System
• Influences on Digestion and Absorption
– Psychological, Chemical, Bacterial Influences
• Nutrition and GI Disorders
Signaling Systems:
Command, Control, Defense
• Nervous system
– Nerves carry info back and forth between tissues
and the brain using chemical signals known as
neurotransmitters.
– The Central Nervous System (CNS) regulates GI
activity in 2 ways:
• Enteric nervous system: _______________________
• Autonomic nervous system: ____________________
_____________________________________________
– Responses to sight, smell, thought of food by ___________
__________________________________________________
Central Nervous System
Signaling Systems:
Command, Control, Defense
• Hormonal system
– Hormones: chemical messengers that travel in the
bloodstream
1. _______________________________________
_______________________________________
2. __________________________by sending
messages to your CNS.
• Thus, your CNS and hormones work together
to coordinate movement and secretions of the
GI tract.
Signaling Systems:
Command, Control, Defense
• Immune System
– Purpose: ____________________________________
– Role of GI tract
• Immune Response
– Macrophages: “big eaters”  ___________________________
______________________________________________________
– Natural killer cells: ____________________________________
• Location of lymphoid tissues
– Lymphocytes: white blood cells present in __________________
» Some types produce antibodies – protein molecules that tag,
neutralize, and help destroy bacteria/viruses or toxins.
Immune System
Influences on Digestion and
Absorption
• Psychological influences
– Positive: Taste, smell, presentation of food
– Negative: Stress, fear, depression
• Example:
• Chemical influences
– Cooking  __________________________________________
______________________________________________________
______________________________________________________
• Bacterial influences
– HCl acid kills most bacteria
• If lives  food borne illnesses, gastritis, ulcer, etc.
Nutrition and GI Disorders
• Constipation (< 3x/week)
– Hard, dry, infrequent stools
– Reduced by _______________________________
___________________________
• Diarrhea (> 3x/day)
– Loose, watery, frequent stools
– Symptom of diseases/infections  ____________
– Can cause dehydration
– _________________________________________
_______________________can help reduce diarrhea
What is Dietary Fiber?
• Fiber: a type of carbohydrate your body cannot digest
with enzymes alone
• 2 types:
– Soluble fiber: __________________________________
• Can lower glucose, blood cholesterol
• Fermented by bacteria in the colon into gases
• Food sources: oatmeal, nuts, beans, lentils, apples, blueberries
– Insoluble fiber: __________________________________
• Provides bulking  absorbs water  ease of defecation
• Helps food move through your digestive system
• Food sources: wheat, whole bread, brown rice, cucumbers,
tomatoes
Nutrition and GI Disorders
• Diverticulosis
– Pouches along colon develop as people age
• 10-25% people  pouches become infected
– __________________reduces formation:
• Low-fiber diet 
• Heartburn and GERD
– Chronic heartburn  GERD
– Reduced by _________________________
– Smoking weakens the esophageal
sphincter
– Being overweight often worsens symptoms
Nutrition and GI Disorders
• Irritable Bowel Movement (IBS)
– Causes abdominal pain, diarrhea, or constipation
and cramps
– Stress and certain foods aggravate the symptoms
• Examples: milk, beans, chocolate, alcohol
– Associated with reproductive hormones
– Can usually be controlled by _________________
__________________________________________
• Stress management
Nutrition and GI Disorders
• Colorectal cancer: cancer in colon or rectum
– ____ leading cause of cancer-related deaths in the
US
– Eating a lot of red meat and low fiber food can
increase risks
– __________________________may reduce risk:
• Hypothesis: more fiber  goes down the GI tract faster,
dilution of carcinogens in a bulkier stool, etc…
• BUT, human/animal studies do not support those
theories.
Nutrition and GI Disorders
• Ulcers
– Pain in the upper abdomen
• Sore is in duodenum: duodenal ulcer
• Sore is in stomach: gastric ulcer
– Can cause nausea, vomiting, loss of appetite, and weight
loss
– Cause: ________________________________________
________________________________________________
• Functional dyspepsia
– Chronic pain in the upper abdomen ________________
_______________________________________________
– Treat with _____________________________________