Use three sentences to explain the three nutritional needs an adequate diet must satisfy
- Provides energy for cellular processes, including ATP synthesis.
- Supplies organic building blocks (e.g., amino acids, fatty acids) for the construction of biomolecules.
- Includes essential nutrients that the body cannot synthesize, like some amino acids, fatty acids, vitamins, and minerals.
What are essential amino acids? What must vegetarians do in order to obtain them?
Essential amino acids are amino acids that animals must obtain from their diet, as their bodies cannot synthesize them. Vegetarians can obtain all essential amino acids by eating a variety of plant-based protein sources, such as grains and legumes, which complement each other.
Which category of vitamin, water soluble or fat
soluble, is most
likely to result in overdose? Why?
Fat-soluble vitamins (A, D, E, and K) are more likely to cause overdose because they are stored in body fat and liver rather than excreted through urine, leading to toxicity if taken excessively.
What is the difference between malnutrition and undernutrition?
Malnutrition refers to imbalanced nutrient intake, including deficiencies and excesses. Undernutrition is specifically about a lack of calories or nutrients, leading to underweight and related health issues.
Ingestion
Intake of food.
Digestion
Breaking down food mechanically and chemically to smaller molecules.
Absorption
Uptake of nutrients into body cells.
Elimination
Removal of undigested material from the body.
Filter Feeding (e.g., whales)
Sifting small organisms or particles from water.
Substrate Feeding (e.g., caterpillars)
Living in or on their food source.
Fluid Feeding (e.g., mosquitoes)
Sucking nutrient-rich fluid from a host.
Bulk Feeding (e.g., humans)
Eating large food pieces.
Distinguish between mechanical digestion and chemical digestion.
Mechanical digestion involves physically breaking food into smaller pieces (e.g., chewing). Chemical digestion uses enzymes to break down food molecules into absorbable components.
What is enzymatic hydrolysis?
Enzymatic hydrolysis is the chemical breakdown of food by enzymes, adding water to break bonds within macromolecules.
Organic Macromolecules and Building Blocks:
- Carbohydrates → Monosaccharides
- Proteins → Amino acids
- Nucleic acids → Nucleotides
- Lipids → Fatty acids and glycerol
In what sense are nutrients from a recently ingested meal not really
“inside” your body
before they enter the absorption stage of food processing?
Nutrients from food are technically "outside" the body until they cross the intestinal lining during absorption, moving from the gut lumen into cells
Explain the difference between intracellular and extracellular
digestion and give a
description of each process in different organisms.
Intracellular digestion (e.g., sponges) involves cells directly engulfing food particles. Extracellular digestion occurs in a digestive system, where food is broken down outside cells and then absorbed.
What is an alimentary canal? Where does it start and end?
The alimentary canal is a digestive tract that extends from the mouth to the anus, allowing food to be digested in sequential compartments.
Why does saliva contain so much amylase?
Amylase in saliva begins breaking down starches into sugars, an essential first step in carbohydrate digestion
How is food kept from entering the trachea when we swallow?
The epiglottis covers the trachea during swallowing, directing food into the esophagus and preventing it from entering the lungs.
What is peristalsis and where does it begin?
the rhythmic contraction of muscles in the digestive tract that starts in the esophagus to push food toward the stomach and throughout the intestines.
What are the two functions of the stomach?
The stomach mechanically churns food and chemically digests proteins with gastric juice, including hydrochloric acid and enzymes.
Stomach Structures:
- Mucus cells secrete mucus to protect the stomach lining; chief cells produce pepsinogen (activated to pepsin); parietal cells secrete hydrochloric acid, aiding digestion.
What is the digestive function of the liver?
The liver produces bile, which aids in fat digestion by emulsifying fats in the small intestine
What is the function of bile? Where is it stored?
Bile emulsifies fats, making them easier for enzymes to break down. It is stored in the gallbladder
What are the two digestive functions of the small intestine?
The small intestine completes digestion and absorbs nutrients into the bloodstream
Enzyme Activity in Digestion
Different enzymes in each digestive region break down macromolecules (e.g., amylase in the mouth for carbohydrates, protease in the stomach for proteins, and lipase in the small intestine for fats).
Remember the mantra: Structure fits function. How is that true for
the villi of the small
intestine?
<p>Villi increase the small intestine's surface area, enhancing nutrient absorption due to their large surface area and close proximity to blood vessels.</p> <br>
The small intestine connects to the large intestine at a T-shaped
junction. One arm forms a
blind pouch called the cecum. What is
the cecum’s role in grazing animals?
The cecum helps in digesting plant material, as it contains bacteria that break down cellulose
Where is the human appendix located? What function does it have?
The appendix is located at the junction of the small and large intestines. It may play a role in immune function and gut microbiome maintenance.
What is a major function of the colon?
the colon reabsorbs water from digested material, forming and storing feces.
What makes up the feces?
Feces consist of undigested food, bacteria, cells from the digestive tract lining, and waste products
Dietary Specialization in Teeth
Herbivores have flat teeth for grinding plants; carnivores have sharp teeth for tearing meat; omnivores possess both types, reflecting their mixed diet.
Why do herbivores have longer alimentary canals than carnivores?
Herbivores have longer alimentary canals for more extensive breakdown and absorption of plant materials, which are harder to digest.
The colon is inhabited by an immense number of bacteria which comprise part of your microbiome. What do these mutualistic symbiotic bacteria do for you?
Symbiotic bacteria help in digestion, producing vitamins, aiding immunity, and breaking down complex carbohydrates.
Does stress cause ulcers? Discuss the finding that received the 2005 Nobel Prize
While stress can exacerbate symptoms, most ulcers are caused by Helicobacter pylori infection. This discovery won the Nobel Prize in 2005.
How can fecal microbial transplantation play in a role in treating intestinal infections?
Transplanting healthy microbiota can help treat infections like Clostridium difficile, restoring gut health by reintroducing beneficial bacteria.
Mutualistic symbiosis is important to digestion in many other species
besides man. How do
herbivores manage to get their energy from
plant cellulose material when they do not have
the ability to
make enzymes to digest cellulose
Herbivores rely on mutualistic bacteria in their gut to digest cellulose since they lack enzymes to break down this complex carbohydrate.
Hormonal Regulation in Digestion:
Digestive hormones like gastrin, secretin, and cholecystokinin (CCK) manage enzyme release and feedback pathways, maintaining balanced digestion.
Glucose Homeostasis:
Insulin lowers blood glucose by promoting uptake into cells, while glucagon raises it by stimulating glycogen breakdown in the liver.
Type 1 diabetes
is an autoimmune condition where the body attacks insulin-producing cells, requiring insulin injections.
Type 2 diabetes
results from insulin resistance, often managed through lifestyle changes and medications.