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 _____________________________________